随车液压起重机的控制外文翻译、中英文翻译、外文文献翻译

中英文对照外文翻译文献(文档含英文原文和中文翻译)原文：FEATURE-BASED COMPONENT MODELS FOR VIRTUALPROTOTYPING OF HYDRAULIC SYSTERMAbstract:This paper proposes a feature-based approach for the virtual prototyping of hydraulic systems. It presents a framework which allows the designer to develop a virtual hydraulic system prototype in a more intuitive manner, i.e. through assembly of virtual components with engineering data. The approach is based on identifying the data required for the development of the virtual prototypes, and separating the information into behaviour, structural, and product attributes. Suitable representations of these attributes are presented, and the framework for the feature-based virtual prototyping approach is established,based on the hierarchical structure of components in a hydraulic system. The proposed framework not only provides a precise model of the hydraulic prototype but also offers the possibility of designing variation classes of prototypes whose members are derived by changing certain virtual components with different features.Key words: Computer-aided engineering; Fluid power systems;Virtualprototyping1.IntroductionHydraulic system design can be viewed as a function-to-form transformation process that maps an explicit set of requirements into a physical realisable fluid power system. The process involves three main stages: the functional specification stage,the configuration design stage, and the prototyping stage.The format for the description of the design in each stage is different.The functional specification stage constitutes the initial design work. The objective is to map the design requirements. To achieve this, the design problems are specified Correspondence and offprint requests to: Dr S. C. Fok, Schoool of Mechanical and Production Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798. The designer must identify the performance attributes, which can include pressure, force, speed, and flowrate, with the required properties such as size, cost, safety and operating sequence. performance requirements for each attribute. In this stage, the design is abstracted in terms of the performance attributes with associated values.The objective of the configuration design stage is to synthesise a hydraulic circuit that performs the required functions conforming to the performance standards within defined constraints. A typical hydraulic system is made up of many subsystems. The smallest building block in a subsystem is the standard hydraulic component (such as valves, cylinders,pumps, etc.). Each type of standard component serves a specific elemental function. The design effort in the configuration design stage is fundamentally a search for a set of optimal arrangements of standard components (i.e. hydraulic circuit) to fulfil the functional requirements of the system. Based on this framework, the designers would normally decompose the overall system functions in terms of subfunctions. This will partition the search space and confine the search for smaller hydraulic subcircuits to perform the subfunctions.Computers are often used to support the configuration design process. For example, Kota and Lee devised a graph-based strategy to automate the configuration of hydraulic circuits. After the development of the hydraulic circuits, digital simulation tools are often used to study and evaluate these configurations. With these tools, designers can compare the behaviour of different circuits and also analyse the effects when subcircuits are combined. In the configuration design stage, the design is traditionally represented as a circuit drawing using standard icons to symbolise the type of standard component. This is a form of directed graph S(C,E) where the circuit S contains components C in the form of nodes with relations between components denoted by edges E.The prototyping stage is the verification phase of the system design process where the proposed hydraulic circuit from the configuration design stage isdeveloped and evaluated. Physical prototyping aims to build a physical prototype of the hydraulic system 666 S. C. Fok et al. using industrial available components. The process of physical prototyping involves the following: Search for appropriate standard components from different manufacturers. Pre-evaluation and selection of components based on individual component cost, size, and specification, and compatibility factors between components. Procurement and assembly of the selected components.Test and evaluate the physical prototype based on the overall system requirements. Use other components or redesign the circuit (or subcircuits)if necessary.Besides dynamics, the development of the physical prototype must take into consideration other factors including structure,cost, and weight. The dynamics data are used to confirm the fluid power system behaviour whereas the geometric information is used to examine the assembly properties. The development of the physical prototype will provide the actual performance,structure, and cost of the design.The main disadvantage of physical prototyping is that it is very tedious and time consuming to look for a set of suitable combinations of standard components from among so many manufacturers. Although the basic functions of the same types of standard component from different manufacturers do not differ, their dynamics, structural and cost characteristics may not be similar, because of design variation. Hence, for a given hydraulic circuit, different combinations of parts from differentmanufacturers can have implications on the resulting system,in terms of dynamics, structure, and cost. Value engineering can be used at this stage to improve the system design by improving the attributes at the component level. This includes maximizing the performance-to-cost ratio and minimising the size-to-performance ratio. Virtual prototyping can be viewed as a computer-aided design process, which employs modelling and simulating tools to address the broad issues of physical layout, operationalconcept, functional specifications, and dynamics analysis under various operating environments. The main advantage of virtual prototyping is that a hydraulic system prototype can be assembled, analysed, and modified using digital computers without the need for physical components, thus saving lead time and cost.The main requirement of a virtual hydraulic system prototype is to provide the same information as a physical prototype for the designer to make decisions.To achieve this, the virtual prototype must provide suitable and comprehensive representations of different data. Furthermore, transformation from one representation to another should proceed formally. Xiang et al. have reviewed the past and current computer-aided design and prototyping tools for fluid power systems. The work revealed that the current tools could not provide a completerepresentation of the design abstractions at the prototyping stage for design judgement. Most of the tools concentrate on the dynamics behaviour. Vital geometrical and product information that relates to the system prototype consideration and evaluation is frequently missing.To advance the development of computer-aided virtual prototyping tools for fluid power systems, there is a need to address the formal representations of different abstractions of behaviour,structural, and product data along with their integration. This paper focuses on these issues and proposes the formalism of a unified component model and the taxonomy based on the feature-based approach. In Section 2, we discuss the feature- based approach focusing on the key information and their representations required for hydraulic system prototyping. Section 3 presents a formalism of the feature-based model and structure for the development of virtual hydraulic system prototypes.The structure is illustrated with an example. Future work and conclusions are given in Section 4.2. Feature-Based ApproachFeatures can be defined as information sets that refer to aspects of attributes that can be used in reasoning about the design, engineering or manufacturing processes. The concept of using features to integrate CAD/CAPP/CAM is not new and there are many papers on the application of this approach in CIM. In all these applications, the feature model is regarded as the basis whereas design by features is the key for the integration. To develop a feature model, the relevant information concerning the design must be identified and grouped into sets based on the nature of the information. The relevant information should contain sufficient knowledge for activities such as design, analysis, test, documentation, inspection, and assembly, as well as support various administrative and logistic functions. Design by features is the process of building a model of the design using features as primitive entities. The feature model provides the standardisation of relevant data. Through the design by features approach, vital knowledge of the design will be generated and stored. Together, the feature model and the design by features approach will provide the essential information, which can be used, not only for the simultaneous consideration of many different concerns with the design, but also to interface the many activities in the design realisation process, including the life cycle support operations. The main drawback of the feature-based design approach is that the feature model should be properly defined . This can be difficult, as features are sets of knowledge that are application dependent. The organisation of the features can also be application specific. Non-trivial data-management problems could arise if the feature model is not properly defined. To avoid these problems, the type,representation and structure of the features should be resolved prior to using the feature-based design methodology. The main concern when developing afeature model is that it is application-specific. In the domain of virtual prototyping of hydraulic systems, the details of the constituent standard components must be able to be used to describe the overall system. The component features are bearers of knowledge about that part. To create a suitable feature model for hydraulic system design based on the assembly of standard components, the relevant information associated with various standard components must be identified and classified. This definition Feature-Based Component Models 667 of the component feature set can then be extended to encompass the subsystem feature set based on the hierarchical structure between the components in the subsystem. In the same manner, a hierarchical structure for the hydraulic system feature representation would evolve by considering the system as a hierarchy of subsystems.The necessary information required for a proper description of the virtual prototype must be no less than that derived by the designer from a physical prototype for decision making. These data should generally include the shape, weight, performance properties, cost, dimensions, functionality data, etc. Comparison with the physical prototyping process, the information required for each standard component could be separated into three distinct groups: behaviour attributes, structural attributes, and product attributes.2.1 Behaviour AttributesThe behaviour of a hydraulic component can be defined in terms of the dynamics characteristics used to satisfy the functional requirements. Consider a hydraulic cylinder connected to a load. Its function is to transmit a force from the stroke of the piston to the load. The maximum force it can transmit can be used to define the functionality and the behaviour requirements can be specified in terms of the desired load acceleration characteristics. Hence for a hydraulic component, behaviour attributes express functionality and can be reflected in the dynamics characteristics. The designer is responsible for the proper definition of the overall system behaviour characteristics in terms of the desired dynamics. A standard component will have its own behaviour and provide a specific plex functions that cannot be achieved by a single standard component are derived using a combination of components. Hence, the behaviour of the standard component will play an important role as the individual behaviours of components together with their arrangement can alter the overall system function .The behaviour of a standard component can be nonlinear and can be dependent on the operating conditions. When two components are combined, it is possible that their behaviours can interact and produce undesired or unintended characteristics. These unwanted behaviours are assumed to have been resolved during the configuration design stage. The hydraulic circuit used in theprototyping stage is assumed to be realisable and without any undesirable interacting behaviours. This means that the output behaviour of a component will provide the input to the subsequent component.The representation of behaviours for hydraulic systems has been widely investigated. These representations include transfer functions, state-space and bond graphs. Transfer functions (for single-input–single-output systems) and state-space equations (for multiple-input–multiple-output systems) are based on the approximation of the dynamics about a nominal operating condition. The power bond graph model is based on the causal effects that describe the energy transformations in the hydraulic system. This approach is appealing for hydraulic system analysis. The main disadvantage is that the derivation of the dynamics equation in a bond graph of a complicated fluid power system can become very tedious. As a result, recent work has concentrated on the used of artificial intelligence to represent the nonlinear mapping between the input and output data, which can be obtained via experimental work. These nonlinear mappings can be accomplished using artificial neural networks .It is quite natural for a hydraulic system designer to use input–output data to describe the behaviour of a hydraulic component. The configuration design of a hydraulic system is often achieved through steps of function decomposition. To design a hydraulic system, the designer often tries to decompose the functions and their requirements down to the component level.译文：基于原型液压系统特征的机构模型摘要：本文为原型液压系统的设计提出了一种基于特征的方法。

中英文对照起重机术语大全修订版IBMT standardization office【IBMT5AB-IBMT08-IBMT2C-ZZT18】中英文对照起重机术语大全起重机（crane）moblie crane?移动式起重机truck crane?汽车式起重机wheel crane / wheeled crane?轮胎起重机crawler crane / caterpillar crane?履带吊;履带式起重机tower crane?塔吊;?塔式起重机-construction tower cranes / building tower crane?建筑塔式起重机，建筑塔机-luffing jib tower crane?动臂塔式起重机-tower jib crane?塔式挺杆起重机（含义与上同）bridge crane/traveling crane/overhead crane?桥吊；桥式吊车;?桥式起重机-electric traveling crane?电动桥式起重机（俗称行车、天车）-electric double-beam bridge crane?电动双梁桥式起重机portal crane / portal bridge crane门式起重机- semi-goliath crane?半门式起重机- semi-portal bridge crane?半龙门起重机gantry cranes?龙门起重机- rubber tyred gantry crane?轮胎式龙门吊- electric gantry crane?电动龙门式起重机- hook gantry crane?吊钩龙门吊- economical gantry crane?简单龙门起重机;?简易龙门起重机- rubber tyred container gantry crane?轮胎式集装箱龙门起重机barges / floating Cranes?船式起重机;?浮吊;?浮式起重机水上起重机boom crane?吊杆起重机;?桁梁起重机;?臂式起重机;?伸臂起重机bucket crane?料罐起重机;?吊斗起重机building crane?建筑起重机cable crane?索道起重机;?缆索起重机container crane?集装箱起重机electric crane?电动吊车;?电动起重机;?电力起重机electriomagnet crane?电磁铁起重机electric jib crane?电动单臂起重机fixed crane?固定式起重机climbing crane?爬升式起重机；攀爬式起重机fixed derrick crane?固定式动臂起重机fixed jib crane?固定式悬臂起重机flying crane helicopter?起重直升机hoist crane?起重葫芦hoisting crane?升降起重机hook type crane?钩式起重机twin hood crane?双钩吊车mobile crane?移动式吊车;?移动式起重机quay crane?码头起重机;?码头桥式起重机;?港岸起重机revolving track crane?回转式轨道起重机circular crane?旋转式吊车环形吊车roof crane?屋顶起重机transporter crane?桁架式起重机electric crane?电动吊车;?电动起重机gasoline crane?汽油起重机hydraulic crane?液力起重机;?液压起重机derrick crane?人字扒杆人字起重机-travelling derrick crane?移动式人字扒杆jib crane?/?cantilever crane?悬臂式起重机wall crane?壁式起重机heavy duty crane?重型起重机crane output / carrying capacity of crane / lifting capacity of crane?吊车起重能力crane load?起重机起重量;?起重机起重量crane rating?起重机定额;?起重机载重量crane radius?起重机起吊半径;?起重机伸臂活动半径;?起重机伸距craneage?吊车工时crane beam?行车梁起重机大梁crane stair?起重机楼梯hoist drive mechanism?起重机驱动机构travelling crab?起重机小车hoisting controller?起重控制器吊车控制手柄hoisting facility?起重设施lifting gear?起重装置crane (runway) girder?吊车梁crane support wall?吊车支承墙crane boom?起重机吊架;?起重架;?吊车臂;?吊车起重扒杆;?吊杆crane column?吊车柱crane hook / grab?（or lift hook）（?or dolly）起重机吊钩crane jib?起重机吊杆crane bridge?起重机桥crane buffer?吊车缓冲器crane rope / crane cable起重钢绳;?起重机吊索;?吊车钢丝绳crane carriage?起重小车;?横行小车crane carrier?起重机载运车crane controller?起重控制器crane fall?起重机索crane motor / crane hoist type motor?起重机电动机crane platform?起重机平台crane rail?吊车轨，起重机轨道crane runner?吊车司机crane runway?起重机走道;?天车滑道crane weigher?吊车秤crane wheel?吊车车轮crane winch?起重机绞车lifting tackle?起重滑车lever of crane?起重机臂hoisting tools?起重工具吊具lifting rope?吊绳起重钢丝绳起重吊装术语：hoist / load up?起升lower / load down?下降hoist slowly / load up slowly?微微起升lower slowly / load down slowly?微微下降use main hoist/use main line?使用主钩use whip hoist/use whip line?使用小钩raise boom / boom up（臂架类吊车）抬起主臂lower boom / boom down?（同上）降下主臂raise boom slowly / boom up slowly（臂架类吊车）微微抬起主臂lower boom slowly / boom down slowly?（同上）微微降下主臂swing?（根据指挥手势、旗语或）移动摆动stop?停止Emergency stop?紧急停止Extend boom / extend hydranlic boom?（汽车吊类）伸长主臂Retract boom / shorten hydranlic boom?（汽车吊类）缩回主臂raise the boom and lower the load /boom up and load down?（汽车吊类）抬主臂降主钩（俗称顿杆松钩）lower the boom and raise the load /boom dwon and load up?（汽车吊类）降主臂起主钩（俗称趴杆起钩）turn left?向左转turn right?向右转crane output? / carrying capacity of crane / lifting capacity of crane?吊车起重能力crane load?起重机起重量;?起重机起重量crane rating?起重机定额;?起重机载重量crane radius?起重机起吊半径;?起重机伸臂活动半径;?起重机伸距craneage?吊车工时crane beam?行车梁?起重机大梁crane stair?起重机楼梯hoist drive mechanism?起重机驱动机构travelling crab?起重机小车hoisting controller?起重控制器吊车控制手柄hoisting facility?起重设施lifting gear?起重装置crane (runway) girder?吊车梁crane support wall?吊车支承墙crane boom?起重机吊架;?起重架;?吊车臂;?吊车起重扒杆;?吊杆crane column?吊车柱crane hook / grab??（or? lift hook）（?or dolly）起重机吊钩crane jib???起重机吊杆crane bridge?起重机桥crane buffer?吊车缓冲器crane rope / crane cable起重钢绳;?起重机吊索;?吊车钢丝绳crane carriage?起重小车;?横行小车crane carrier?起重机载运车crane controller?起重控制器crane fall?起重机索crane motor / crane hoist type motor?起重机电动机crane platform?起重机平台crane rail?吊车轨，起重机轨道crane runner?吊车司机crane runway?起重机走道;?天车滑道crane weigher?吊车秤crane wheel?吊车车轮crane winch?起重机绞车lifting tackle?起重滑车lever of crane?起重机臂hoisting tools?起重工具?吊具lifting rope?吊绳?起重钢丝绳。

译文：液压汽车起重机的工作原理由飓风丹尼引起的暴雨淹没了北卡罗来纳州夏洛特市的许多地方，小糖溪的河水上涨很快，导致一条火车铁轨栈桥倒塌，一辆内燃机列车坠入河道内。

你可以想象一下，一个412,000磅（186880公斤）的机车是不容易打捞的。

当洪水退去过后，紧急救援队紧急救援队伍带来了三个大型液压汽车起重机——1辆500吨，一辆300吨和一辆175吨，用来把火车从河床里面打捞出来，放置回到轨道上面。

液压汽车起重机利用简单的点对点流体力学概念来举起上千磅重的物品。

液压汽车起重机的设计非常简单，但是他能完成一些看似不可能完成的艰巨任务。

在几分钟内，在公路上这些机器可以举起重达几吨的桥梁；在工厂里，这些机器可以举起重型设备；甚至，在建造海滨房屋的时候帮助打桩。

当有些地方比如海洋世界需要将鲸鱼运送到新的目的地的时候，液压汽车起重机同样可以用来举起装鲸鱼的水箱。

当看到这些液压汽车起重机运行的时候，很难相信它将这些如此重的物品相对轻松的移动，因为这些的物品都是上吨级的。

液压汽车起重机有各种不同的提升力。

只需要通过它的名字就可以轻松的知道许多特定的液压汽车起重机的起重能力，例如：一个40吨吊车能吊起40吨（80000磅或36287 kg ）。

在这里，你将学习起重机如何利用水力学（液压）举起数千英镑的物体，我们会爬进驾驶室向你展示如何操作这些机器。

这全是关于液压的液压起重机是基于一个简单的概念——通过点对点流体力学概念来进行力的传递。

大多数液压机使用的是一些密度很大大到不可压缩的液体。

油（石油）是最常见的被用来做液压机包括液压起重机的不可压缩的液体。

在一个简单的液压系统里面，当一个活塞推动油（石油），油（石油）就将所有的原动力传送到另一个需要带动的活塞。

在一个简单的液压系统里面，当一个活塞被推动，另一个活塞就会被带动。

液压泵产生的压力推动活塞。

在一个液压系统里面的压力由两种液压泵类型中的一种产生：可变排量泵（变量泵）齿轮泵大多数液压汽车起重机使用的是有一对齿合齿轮向液压油加压的双齿轮泵。

附录外文文献原文：The Introduction of cranesA crane is defined as a mechanism for lifting and lowering loads with a hoisting mechanism Shapiro, 1991. Cranes are the most useful and versatile piece of equipment on a vast majority of construction projects. They vary widely in configuration, capacity, mode of operation, intensity of utilization and cost. On a large project, a contractor may have an assortment of cranes for different purposes. Small mobile hydraulic cranes may be used for unloading materials from trucks and for small concrete placement operations, while larger crawler and tower cranes may be used for the erection and removal of forms, the installation of steel reinforcement, the placement of concrete, and the erection of structural steel and precast concrete beams.On many construction sites a crane is needed to lift loads such as concrete skips, reinforcement, and formwork. As the lifting needs of the construction industry have increased and diversified, a large number of general and special purpose cranes have been designed and manufactured. These cranes fall into two categories, those employed in industry and those employed in construction. The most common types of cranes used in construction are mobile, tower, and derrick cranes.1.Mobile cranesA mobile crane is a crane capable of moving under its own power without being restricted to predetermined travel. Mobility is provided by mounting or integrating the crane with trucks or all terrain carriers or rough terrain carriers or by providing crawlers. Truck-mounted cranes have the advantage of being able to move under their own power to the construction site. Additionally, mobile cranes can move about the site, and are often able to do the work of several stationary units.Mobile cranes are used for loading, mounting, carrying large loads and for work performed in the presence of obstacles of various kinds such as power lines and similar technological installations. The essential difficulty is here the swinging of the payload which occurs during working motion and also after the work is completed. This applies particularly to the slewing motion of the crane chassis, for which relatively large angular accelerations and negative accelerations of the chassis are characteristic. Inertia forces together with the centrifugal force and the Carioles force cause the payload to swing as a spherical pendulum. Proper control of the slewing motion of the crane serving to transport a payload to the defined point with simultaneous minimization of the swings when theworking motion is finished plays an important role in the model.Modern mobile cranes include the drive and the control systems. Control systems send the feedback signals from the mechanical structure to the drive systems. In general, they are closed chain mechanisms with flexible members [1].Rotation, load and boom hoisting are fundamental motions the mobile crane. During transfer of the load as well as at the end of the motion process, the motor drive forces, the structure inertia forces, the wind forces and the load inertia forces can result in substantial, undesired oscillations in crane. The structure inertia forces and the load inertia forces can be evaluated with numerical methods, such as the finite element method. However, the drive forces are difficult to describe. During start-up and breaking the output forces of the drive system significantly fluctuate. To reduce the speed variations during start-up and braking the controlled motor must produce torque other than constant [2,3], which in turn affects the performance of the crane.Modern mobile cranes that have been built till today have oft a maximal lifting capacity of 3000 tons and incorporate long booms. Crane structure and drive system must be safe, functionary and as light as possible. For economic and time reasons it is impossible to build prototypes for great cranes. Therefore, it is desirable to determinate the crane dynamic responses with the theoretical calculation.Several published articles on the dynamic responses of mobile crane are available in the open literature. In the mid-seventies Peeken et al. [4] have studied the dynamic forces of a mobile crane during rotation of the boom, using very few degrees of freedom for the dynamic equations and very simply spring-mass system for the crane structure. Later Maczynski et al. [5] studied the load swing of a mobile crane with a four mass-model for the crane structure. Posiadala et al. [6] have researched the lifted load motion with consideration for the change of rotating, booming and load hoisting. However, only the kinematics were studied. Later the influence of the flexibility of the support system on the load motion was investigated by the same author [7]. Recently, Kilicaslan et al. [1] have studied the characteristics of a mobile crane using a flexible multibody dynamics approach. Towarek [16] has concentrated the influence of flexible soil foundation on the dynamic stability of the boom crane. The drive forces, however, in all of those studies were presented by using so called the metho d of ……kinematics forcing‟‟ [6] with assumed velocities or accelerations. In practice this assumption could not comply with the motion during start-up and braking.A detailed and accurate model of a mobile crane can be achieved with the finite element method. Using non-linear finite element theory Gunthner and Kleeberger [9] studied the dynamic responses of lattice mobile cranes. About 2754 beam elements and 80 truss elements were used for modeling of the lattice-boom structure. On this basis a efficient software for mobile crane calculation––NODYA has been developed. However, the influences of the drive systems must be determined by measuring on hoisting of the load[10], or rotating of the crane [11]. This is neither efficient nor convenient for computer simulation of arbitrary crane motions.Studies on the problem of control for the dynamic response of rotary crane are also available. Sato et al. [14], derived a control law so that the transfer a load to a desired position will take place that at the end of the transfer of the swing of the load decays as soon as possible. Gustafsson [15] described a feedback control system for a rotary crane to move a cargo without oscillations and correctly align the cargo at the final position. However, only rigid bodies and elastic joint between the boom and the jib in those studies were considered. The dynamic response of the crane, for this reason, will be global.To improve this situation, a new method for dynamic calculation of mobile cranes will be presented in this paper. In this method, the flexible multibody model of the steel structure will be coupled with the model of the drive systems. In that way the elastic deformation, the rigid body motion of the structure and the dynamic behavior of the drive system can be determined with one integrated model. In this paper this method will be called ……complete dynamic calculation for driven “mechanism”.On the basis of flexible multibody theory and the Lagrangian equations, the system equations for complete dynamic calculation will be established. The drive- and control system will be described as differential equations. The complete system leads to a non-linear system of differential equations. The calculation method has been realized for a hydraulic mobile crane. In addition to the structural elements, the mathematical modeling of hydraulic drive- and control systems is decried. The simulations of crane rotations for arbitrary working conditions will be carried out. As result, a more exact representation of dynamic behavior not only for the crane structure, but also for the drive system will be achieved. Based on the results of these simulations the influences of the accelerations, velocities during start-up and braking of crane motions will be discussed.2.Tower cranesThe tower crane is a crane with a fixed vertical mast that is topped by a rotating boom and equipped with a winch for hoisting and lowering loads (Dickie, 990). Tower cranes are designed for situations which require operation in congested areas. Congestion may arise from the nature of the site or from the nature of the construction project. There is no limitation to the height of a high-rise building that can be constructed with a tower crane. The very high line speeds, up to 304.8 mrmin, available with some models yield good production rates at any height. They provide a considerable horizontal working radius, yet require a small work space on the ground (Chalabi, 1989). Some machines can also operate in winds of up to 72.4 km/h, which is far above mobile crane wind limits.The tower cranes are more economical only for longer term construction operations and higher lifting frequencies. This is because of the fairly extensive planning needed for installation, together with the transportation, erection and dismantling costs.3. Derrick cranesA derrick is a device for raising, lowering, and/or moving loads laterally. The simplest form of the derrick is called a Chicago boom and is usually installed by being mounted to building columns or frames during or after construction (Shapiro and Shapiro, 1991).This derrick arrangement. (i.e., Chicago boom) becomes a guy derrick when it is mounted to a mast and a stiff leg derrick when it is fixed to a frame.The selection of cranes is a central element of the life cycle of the project. Cranes must be selected to satisfy the requirements of the job. An appropriately selected crane contributes to the efficiency, timeliness, and profitability of the project. If the correct crane selection and configuration is not made, cost and safety implications might be created (Hanna, 1994). Decision to select a particular crane depends on many input parameters such as site conditions, cost, safety, and their variability. Many of these parameters are qualitative, and subjective judgments implicit in these terms cannot be directly incorporated into the classical decision making process. One way of selecting crane is achieved using fuzzy logic approach.Cranes are not merely the largest, the most conspicuous, and the most representative equipment of construction sites but also, at various stages of the project, a real “bottleneck” that slows the pace of the construction process. Although the crane can be found standing idle in many instances, yet once it is involved in a particular task ,it becomes an indispensable link in the activity chain, forcing at least two crews(in the loading and the unloading zones) to wait for the service. As analyzed in previous publications [6-8] it is feasible to automate (or, rather, semi-automate) crane navigation in order to achieve higher productivity, better economy, and safe operation. It is necessary to focus on the technical aspects of the conversion of existing crane into large semi-automatic manipulators. By mainly external devices mounted on the crane, it becomes capable of learning, memorizing, and autonomously navigation to reprogrammed targets or through prêt aught paths.The following sections describe various facets of crane automation:First, the necessary components and their technical characteristics are reviewed, along with some selection criteria. These are followed by installation and integration of the new components into an existing crane. Next, the Man –Machine –Interface (MMI) is presented with the different modes of operation it provides. Finally, the highlights of a set of controlled tests are reported followed by conclusions and recommendations.Manual versus automatic operation: The three major degrees of freedom of common tower cranes are illustrated in the picture. In some cases , the crane is mounted on tracks , which provide a fourth degree of freedom , while in other cases the tower is “telescope” or extendable , and /or the “jib” can be raised to a diagonal position. Since these additional degrees of freedom are not used routinely during normal operation but rather are fixed in a certain position for long periods (days or weeks), they are not included in the routineautomatic mode of operation, although their position must be “known” to the control system.外文文献中文翻译：起重机介绍起重机是用来举升机构、抬起或放下货物的器械。

液压英文文献及翻译液压系统1.绪论液压站称液压泵站，是独立的液压装置。

它是按逐级要求供油。

并控制液压油流方向、压力和流量，适用在主机与液压装置可分离的各种液压机械上面。

用户在购后只要将液压站与主机上执行机构（油缸或油马达）用不同的油管相连，液压机械即实现各种规定的动作与工作循环。

液压站是由集成块、泵装置或阀组合、电气盒、油箱电气盒组合而成。

各个部件功能为：泵装置——上装有电机和油泵，其是液压站的动力源，能将机械能转化为液压油压力能。

阀组合－－其板式阀装在立板上，板后管连接，与集成块的功能相同。

油集成块－－是由液压阀及通道体组装而成。

其对液压油实行压力、方向和流量调节。

箱－－是板焊的半封闭容器，上面还装有滤油网、空气滤清器等，是用来储油与油的冷却及过滤。

电气盒－－分两种型式：一种是设置外接引线的端子板；一种是配置了全套控制电器。

液压站工作原理：电机带动油泵转动，然后泵从油箱中吸油并供油，将机械能转化为液压站压力能，液压油通过集成块（或阀组合）实现方向、压力、流量调节后经过外接管路并至液压机械里的油缸或油马达中，从而控制液动机方向变换、力量的大小及速度的快慢，来推动各种液压机械做功。

(1)液压的发展历程在我国液压（含液力，下同）、气动和密封件工业的发展历程，大致可分成三个阶段，即：在20世纪50年代初到60年代初是起步阶段；60-70年代为专业化生产体系的成长阶段；80-90年代为快速发展阶段。

在其中，液压工业始于50年代初从机床行业生产的仿苏的磨床、拉床、仿形车床等液压传动来起步，液压元件由机床厂里的液压车间生产，自产自用。

在进入60年代后，液压技术应用从机床逐渐推广到农业机械与工程机械等领域，原来附属于主机厂里的液压车间有些独立出来，成为液压件的专业生产厂。

在60年代末、70年代初，随着生产机械化的不断发展，特别是在为第二汽车制造厂等提供了高效、自动化设备的带动下，液压元件制造业出现了不断迅速发展的局面，一批中小企业也开始成为液压件专业制造厂。

附录 1：外文翻译随车起重装置的结构与设计相对传统的举升机构,该举升机构只采用了液压缸,使液压系统的管路简单,控制方便,液压系统的可靠性高,且安装方便。

上述的分析与计算,为该机构建立了结构与性能等参数间的数学关系。

有关推销与套筒间的摩擦与磨损,套筒导槽角和翻转角度与举升高度的适应性等问题,将有待进一步的分析研究和结构发。

随车起重装置在国外称为随车吊。

本文按国家标准称其为随车起重装置。

一辆安装了随车起重装置的厢式货车在货物运输中, 不仅显示其防雨防尘的专有功能,而且在货物的装卸方面实现了机械化。

1 随车起重装置的发展随车起重装置的发展, 在国外大体上可分为四个时期。

第一代产品产生于本世纪30 年代末, 其特点主要是单缸举升, 而栏板翻转靠手动, 起升质量为500kg 左右, 栏板(又称载物平台) 触地倾角9°～10°。

目前, 这种产品在东南亚、日本仍在使用, 90 年代, 还在美国得到了新的发展。

第二代产品产生于50 年代初的欧洲市场, 在第一代产品的基础上增加了翻转关门油缸。

举升与翻转分别由二个独立油缸实现。

最常见的是四只油缸的型式, 也有双缸的。

起升质量在500 kg 以上, 载物平台触地倾角10°, 翻转动作凭操作者经验控制。

该种产品目前主要用于美洲及东南亚地区。

第三代产品产生于70 年代末的欧洲市场, 是在第二代产品的基础上增加第五只油缸。

这只油缸在液压系统中主要起相对位置的记忆功能, 使载物平台触地、离地的翻转动作不再由操作者控制而由液压系统本身控制, 从而使升降过程相对平稳与安全。

触地倾角一般为8°～10°。

若兼作厢门用, 因平台尺寸增大, 倾角也可能小于8°。

目前该类产品普遍用于欧美地区。

第四代产品产生于90 年代初, 其液压系统及功能原理同第三代产品, 只增加了记忆油缸的尺寸, 使记忆动作的范围进一步增大。

它不同于第三代产品的关键在于其载物平台增加特殊结构, 由一体改为两体活动联接, 使平台触地后不仅能自动翻转, 而且有一个下沉的动作, 使触地倾角达到6°, 甚至在6以下。

起重机中英⽂对照外⽂翻译⽂献中英⽂对照外⽂翻译(⽂档含英⽂原⽂和中⽂翻译)Control of Tower Cranes WithDouble-Pendulum Payload DynamicsAbstract：The usefulness of cranes is limited because the payload is supported by an overhead suspension cable that allows oscilation to occur during crane motion. Under certain conditions, the payload dynamics may introduce an additional oscillatory mode that creates a double pendulum. This paper presents an analysis of this effect on tower cranes. This paper also reviews a command generation technique to suppress the oscillatory dynamics with robustness to frequency changes. Experimental results are presented to verify that the proposed method can improve the ability of crane operators to drive a double-pendulum tower crane. The performance improvements occurred during both local and teleoperated control.Key words：Crane , input shaping , tower crane oscillation , vibrationI. INTRODUCTIONThe study of crane dynamics and advanced control methods has received significant attention. Cranes can roughly be divided into three categories based upontheir primary dynamic properties and the coordinate system that most naturally describes the location of the suspension cable connection point. The first category, bridge cranes, operate in Cartesian space, as shown in Fig. 1(a). The trolley moves along a bridge, whose motion is perpendicular to that of the trolley. Bridge cranes that can travel on a mobile base are often called gantry cranes. Bridge cranes are common in factories, warehouses, and shipyards.The second major category of cranes is boom cranes, such as the one sketched in Fig. 1(b). Boom cranes are best described in spherical coordinates, where a boom rotates aboutaxes both perpendicular and parallel to the ground. In Fig. 1(b), ψis the rotation aboutthe vertical, Z-axis, and θis the rotation about the horizontal, Y -axis. The payload is supported from a suspension cable at the end of the boom. Boom cranes are often placed on a mobile base that allows them to change their workspace.The third major category of cranes is tower cranes, like the one sketched in Fig. 1(c). These are most naturally described by cylindrical coordinates. A horizontal jib arm rotates around a vertical tower. The payload is supported by a cable from the trolley, which moves radially along the jib arm. Tower cranes are commonly used in the construction of multistory buildings and have the advantage of having a small footprint-to-workspace ratio. Primary disadvantages of tower and boom cranes, from a control design viewpoint, are the nonlinear dynamics due to the rotational nature of the cranes, in addition to the less intuitive natural coordinate systems.A common characteristic among all cranes is that the pay- load is supported via an overhead suspension cable. While this provides the hoisting functionality of the crane, it also presents several challenges, the primary of which is payload oscillation. Motion of the crane will often lead to large payload oscillations. These payload oscillations have many detrimental effects including degrading payload positioning accuracy, increasing task completion time, and decreasing safety. A large research effort has been directed at reducing oscillations. An overview of these efforts in crane control, concentrating mainly on feedback methods, is provided in [1]. Some researchers have proposed smooth commands to reduce excitation of system flexible modes [2]–[5]. Crane control methods based on command shaping are reviewed in [6]. Many researchers have focused on feedback methods, which necessitate the addition necessitate the addition of sensors to the crane and can prove difficult to use in conjunction with human operators. For example, some quayside cranes have been equipped with sophisticated feedback control systems to dampen payload sway. However, the motions induced by the computer control annoyed some of the human operators. As a result, the human operators disabled the feedback controllers. Given that the vast majority of cranes are driven by human operators and will never be equipped with computer-based feedback, feedback methods are not considered in this paper.Input shaping [7], [8] is one control method that dramatically reduces payload oscillation by intelligently shaping the commands generated by human operators [9], [10]. Using rough estimates of system natural frequencies and damping ratios, a series of impulses, called the input shaper, is designed. The convolution of the input shaper and the original command is then used to drive the system. This process is demonstrated with atwo-impulse input shaper and a step command in Fig. 2. Note that the rise time of the command is increased by the duration of the input shaper. This small increase in the rise time isnormally on the order of 0.5–1 periods of the dominant vibration mode.Fig. 1. Sketches of (a) bridge crane, (b) boom crane, (c) and tower crane.Fig. 2. Input-shaping process.Input shaping has been successfully implemented on many vibratory systems including bridge [11]–[13], tower [14]–[16], and boom [17], [18] cranes, coordinate measurement machines[19]–[21], robotic arms [8], [22], [23], demining robots [24], and micro-milling machines [25].Most input-shaping techniques are based upon linear system theory. However, some research efforts have examined the extension of input shaping to nonlinear systems [26], [14]. Input shapers that are effective despite system nonlinearities have been developed. These include input shapers for nonlinear actuator dynamics, friction, and dynamic nonlinearities [14], [27]–[31]. One method of dealing with nonlinearities is the use of adaptive or learning input shapers [32]–[34].Despite these efforts, the simplest and most common way to address system nonlinearities is to utilize a robust input shaper [35]. An input shaper that is more robust to changes in system parameters will generally be more robust to system nonlinearities that manifest themselves as changes in the linearized frequencies. In addition to designing robust shapers, input shapers can also be designed to suppress multiple modes of vibration [36]–[38].In Section II, the mobile tower crane used during experimental tests for this paper is presented. In Section III, planar and 3-D models of a tower crane are examined to highlight important dynamic effects. Section IV presents a method to design multimode input shapers with specified levels of robustness. InSection V, these methods are implemented on a tower crane with double-pendulum payload dynamics. Finally, in Section VI, the effect of the robust shapers on human operator performance is presented for both local and teleoperated control.II. MOBILE TOWER CRANEThe mobile tower crane, shown in Fig. 3, has teleoperation capabilities that allow it to be operated in real-time from anywhere in the world via the Internet [15]. The tower portion of the crane, shown in Fig. 3(a), is approximately 2 m tall with a 1 m jib arm. It is actuated by Siemens synchronous, AC servomotors. The jib is capable of 340°rotation about the tower. The trolley moves radially along the jib via a lead screw, and a hoisting motor controls the suspension cable length. Motor encoders are used for PD feedback control of trolley motion in the slewing and radial directions. A Siemens digital camera is mounted to the trolley and records the swing deflection of the hook at a sampling rate of 50 Hz [15].The measurement resolution of the camera depends on the suspension cable length. For the cable lengths used in this research, the resolution is approximately 0.08°. This is equivalent to a 1.4 mm hook displacement at a cable length of 1 m. In this work, the camera is not used for feedback control of the payload oscillation. The experimental results presented in this paper utilize encoder data to describe jib and trolley position and camera data to measure the deflection angles of the hook. Base mobility is provided by DC motors with omnidirectional wheels attached to each support leg, as shown in Fig. 3(b). The base is under PD control using two HiBot SH2-based microcontrollers, with feedback from motor-shaft-mounted encoders. The mobile base was kept stationary during all experiments presented in this paper. Therefore, the mobile tower crane operated as a standard tower crane.Table I summarizes the performance characteristics of the tower crane. It should be noted that most of these limits areenforced via software and are not the physical limitations of the system. These limitations are enforced to more closely match theoperational parameters of full-sized tower cranes.Fig. 3. Mobile, portable tower crane, (a) mobile tower crane, (b) mobile crane base.TABLE I MOBILE TOWER CRANE PERFORMANCE LIMITSFig. 4 Sketch of tower crane with a double-pendulum dynamics.III. TOWER CRANE MODELFig.4 shows a sketch of a tower crane with a double-pendulum payload configuration. The jib rotates by an angle around the vertical axis Z parallelto the tower column. The trolley moves radially along the jib; its position along the jib is described by r . The suspension cable length from the trolley to the hook is represented by an inflexible, massless cable of variable length 1l . The payload is connected to the hook via an inflexible, massless cable of length 2l . Both the hook and the payload are represented as point masses having masses h m and p m , respectively.The angles describing the position of the hook are shown in Fig. 5(a). The angle φrepresents a deflection in the radial direction, along the jib. The angle χ represents a tangential deflection, perpendicular to the jib. In Fig. 5(a), φ is in the plane of the page, and χ lies in a plane out of the page. The angles describing the payload position are shown in Fig. 5(b). Notice that these angles are defined relative to a line from the trolley to the hook. If there is no deflection of the hook, then the angleγ describes radial deflections, along the jib, and the angle α represents deflections perpendicular to the jib, in the tangential direction. The equations of motion for this model were derived using a commercial dynamics package, but they are too complex to show in their entirety here, as they are each over a page in length.To give some insight into the double-pendulum model, the position of the hook and payload within the Newtonian frame XYZ are written as —h q and —p q , respectivelyWhere -I , -J and -K are unit vectors in the X , Y , and Z directions. The Lagrangian may then be written asFig. 5. (a) Angles describing hook motion. (b) Angles describing payload motion.Fig. 6. Experimental and simulated responses of radial motion.(a) Hook responses (φ) for m 48.01=l ，(b) Hook responses for m 28.11=lThe motion of the trolley can be represented in terms of the system inputs. The position of the trolley —tr q in the Newtonian frame is described byThis position, or its derivatives, can be used as the input to any number of models of a spherical double-pendulum. More detailed discussion of the dynamics of spherical double pendulums can be found in [39]–[42].The addition of the second mass and resulting double-pendulum dramatically increases the complexity of the equations of motion beyond the more commonly used single-pendulum tower model [1], [16], [43]–[46]. This fact can been seen in the Lagrangian. In (3), the terms in the square brackets represent those that remain for the single-pendulum model; no —p q terms appear. This significantly reduces the complexity of the equations because —p q is a function of the inputs and all four angles shown in Fig. 5.It should be reiterated that such a complex dynamic model is not used to design the input-shaping controllers presented in later sections. The model was developed as a vehicle to evaluate the proposed control method over a variety of operating conditions and demonstrate its effectiveness. The controller is designed using a much simpler, planar model.A. Experimental V erification of the ModelThe full, nonlinear equations of motion were experimentally verified using several test cases. Fig.6 shows two cases involving only radial motion. The trolley was driven at maximum velocity for a distance of 0.30 m, with 2l =0.45m .The payload mass p m for both cases was 0.15 kg and the hook mass h m was approximately 0.105 kg. The two cases shown in Fig. 6 present extremes of suspension cable lengths 1l . In Fig. 6(a), 1l is 0.48 m , close to the minimum length that can be measured by the overhead camera. At this length, the double-pendulum effect is immediately noticeable. One can see that the experimental and simulated responses closely match. In Fig. 6(b), 1l is 1.28 m, the maximum length possible while keeping the payload from hitting the ground. At this length, the second mode of oscillation has much less effect on the response. The model closely matches the experimental response for this case as well. The responses for a linearized, planar model, which will be developed in Section III-B, are also shown in Fig. 6. The responses from this planar model closely match both the experimental results and the responses of the full, nonlinear model for both suspension cable lengths.Fig. 7. Hook responses to 20°jib rotation:(a) φ (radial) response;(b) χ (tangential) response.Fig. 8. Hook responses to 90°jib rotation:φ(radial) response;(b) χ(tangential) response.(a)If the trolley position is held constant and the jib is rotated, then the rotational and centripetal accelerations cause oscillation in both the radial and tangential directions. This can be seen in the simulation responses from the full nonlinear model in Figs. 7 and 8. In Fig. 7, the trolley is held at a fixed position of r = 0.75 m, while the jib is rotated 20°. This relatively small rotation only slightly excites oscillation in the radial direction, as shown in Fig. 7(a). The vibratory dynamics are dominated byoscillations in the tangential direction, χ, as shown in Fig. 7(b). If, however, a large angular displacement of the jib occurs, then significant oscillation will occur in both the radial and tangential directions, as shown in Fig. 8. In this case, the trolley was fixed at r = 0.75 m and the jib was rotated 90°. Figs. 7 and 8 show that the experimental responses closely match those predicted by the model for these rotational motions. Part of the deviation in Fig. 8(b) can be attributed to the unevenness of the floor on which the crane sits. After the 90°jib rotation the hook and payload oscillate about a slightly different equilibrium point, as measured by the overhead camera.Fig.9.Planardouble-pendulummodel.B.Dynamic AnalysisIf the motion of the tower crane is limited to trolley motion, like the responses shown in Fig. 6, then the model may be simplified to that shown in Fig. 9. This model simplifies the analysis of the system dynamics and provides simple estimates of the two natural frequencies of the double pendulum. These estimates will be used to develop input shapers for the double-pendulum tower crane.The crane is moved by applying a force )(t u to the trolley. A cable of length 1l hangs below the trolley and supports a hook, of mass h m , to which the payload is attached using rigging cables. The rigging and payload are modeled as a second cable, of length 2l and point mass p m . Assuming that the cable and rigging lengths do not change during the motion, the linearized equations of motion, assuming zero initial conditions, arewhere φ and γ describe the angles of the two pendulums, R is the ratio of the payload mass to the hook mass, and g is the acceleration due to gravity.The linearized frequencies of the double-pendulum dynamics modeled in (5) are [47]Where Note that the frequencies depend on the two cable lengths and the mass ratio.Fig. 10. Variation of first and second mode frequencies when m l l 8.121=+.。

外文文献翻译(含：英文原文及中文译文)英文原文Hydraulic systemW Arnold1 IntroductionThe hydraulic station is called a hydraulic pump station and is an independent hydraulic device. It is step by step to supply oil. And control the direction of hydraulic oil flow, pressure and flow, suitable for the host and hydraulic equipment can be separated on the various hydraulic machinery.After the purchase, the user only needs to connect the hydraulic station and the actuator (hydraulic or oil motor) on the mainframe with different tubings. The hydraulic machine can realize various specified actions and working cycles.The hydraulic station is a combination of manifolds, pump units or valve assemblies, electrical boxes, and tank electrical boxes. Each part function is:The pump unit is equipped with a motor and an oil pump, which is the power source of the hydraulic station and can convert mechanical energy into hydraulic oil pressure energy.V alve combination - its plate valve is mounted on the vertical plate, and the rear plate is connected with the same function as the manifold.Oil manifolds - assembled from hydraulic valves and channel bodies. It regulates hydraulic oil pressure, direction and flow.Box--a semi-closed container for plate welding. It is also equipped with an oil screen, an air filter, etc., which is used for cooling and filtering of oil and oil.Electrical box - divided into two types: one is to set the external lead terminal board; one is equipped with a full set of control appliances.The working principle of the hydraulic station: The motor drives the oil pump to rotate, then the pump sucks oil from the oil tank and supplies oil, converts the mechanical energy into hydraulic pressure energy, and the hydraulic oil passes through the manifold (or valve assembly) to adjust the direction, pressure and flow and then passes through the external tube. The way to the hydraulic cylinder or oil motor in the hydraulic machinery, so as to control the direction of the hydraulic motor, the strength of the speed and speed, to promote all kinds of hydraulic machinery to do work.(1) Development history of hydraulic pressureThe development history of hydraulics (including hydraulic power, the same below), pneumatics, and seals industry in China can be roughly divided into three stages, namely: the starting stage in the early 1950s to the early 60s; and the professional in the 60s and 70s. The growth stage of the production system; the 80-90's is a stage of rapid development. Among them, the hydraulic industry began in the early 1950s with thedevelopment of hydraulic machines such as Grinding Machines, broaching machines, and profiling lathes, which were produced by the machine tool industry. The hydraulic components were produced by the hydraulic workshop in the machine tool factory, and were produced for self use. After entering the 1960s, the application of hydraulic technology was gradually promoted from the machine tool to the agricultural machinery and engineering machinery. The original hydraulic workshop attached to the main engine plant was independent and became a professional manufacturer of hydraulic components. In the late 1960s and early 1970s, with the continuous development of mechanization of production, particularly in the provision of highly efficient and automated equipment for the second automobile manufacturing plant, the hydraulic component manufacturing industry witnessed rapid development. The batch of small and medium-sized enterprises also began to become specialized manufacturers of hydraulic parts. In 1968, the annual output of hydraulic components in China was close to 200,000 pieces. In 1973, in the fields of machine tools, agricultural machinery, construction machinery and other industries, the professional factory for the production of hydraulic parts has grown to over 100, and its annual output exceeds 1 million pieces. Such an independent hydraulic component manufacturing industry has taken shape. At this time, the hydraulic product has evolved from the original imitation Su product intoa combination of imported technology and self-designed products. The pressure has been developed towards medium and high pressures, and electro-hydraulic servo valves and systems have been developed. The application of hydraulics has been further expanded. The pneumatic industry started a few years later than hydraulics, and it was only in 1967 that it began to establish a professional pneumatic components factory. Pneumatic components began to be manufactured and sold as commodities. Its sealing industry including rubber seals, flexible graphite seals, and mechanical seals started from the production of common O-rings, oil seals, and other extruded rubber seals and asbestos seal products in the early 1950s. In the early 1960s, it began to develop and produce flexible products. Graphite seals and mechanical seals and other products. In the 1970s, a batch of batches of professional production plants began to be established one after another in the systems of the former Ministry of Combustion, the Ministry of Agriculture, and the Ministry of Agricultural Machinery, formally forming the industry, which laid the foundation for the development of the seal industry.In the 1980s, under the guidance of the national policy of reform and opening up, with the continuous development of the machinery industry, the contradiction between the basic components lags behind the host computer has become increasingly prominent and caused the attention of all relevant departments. To this end, the former Ministry of Machinesestablished the General Infrastructure Industry Bureau in 1982, and unified the original pneumatic, hydraulic, and seal specialties that were scattered in the industries of machine tools, agricultural machinery, and construction machinery, etc. The management of a piece of office, so that the industry in the planning, investment, the introduction of technology and scientific research and development and other aspects of the basic parts of the bureau's guidance and support. This has entered a period of rapid development, it has introduced more than 60 foreign advanced technology, of which more than 40 hydraulic, pneumatic 7, after digestion and absorption and technological transformation, are now mass production, and has become the industry's leading products . In recent years, the industry has intensified its technological transformation. From 1991 to 1998, the total investment of national, local, and corporate self-raised funds totaled about 2 billion yuan, of which more than 1.6 billion were hydraulic. After continuous technological transformation and technological breakthroughs, the technical level of a group of major enterprises has been further improved, and technological equipment has also been greatly improved, laying a good foundation for forming a high starting point, specialization, and mass production. In recent years, under the guidance of the principle of common development of multiple ownership systems in the country, various small and medium-sized enterprises with different ownership have rapidly emerged and haveshown great vitality. With the further opening up of the country, foreign-funded enterprises have developed rapidly, which plays an important role in raising industry standards and expanding exports. So far China has established joint ventures with famous manufacturers in the United States, Germany, Japan and other countries or directly established piston pumps/motors, planetary speed reducers, hydraulic control valves, steering gears, hydraulic systems, hydrostatic transmissions, and hydraulic components. The company has more than 50 manufacturing enterprises such as castings, pneumatic control valves, cylinders, gas processing triplets, rubber seals, and mechanical seals, and has attracted more than 200 million U.S. dollars in foreign capital.(2) Current statusBasic profileAfter more than 40 years of hard work, China's hydraulics, pneumatics and seals industry has formed a complete industrial system with a certain level of production capacity and technical level. According to the statistics of the third n ational industrial census in 1995, China’s state-owned, privately-owned, cooperative, village-run, individual, and “funded enterprises” have annual sales income of more than 1 million yuan in hydraulic, pneumatic, and seal industrial townships and above. There are a total of more than 1,300 companies, including about 700 hydraulics, and about 300 pneumatic and sealing parts. According to thestatistics of the international industry in 1996, the total output value of the hydraulic industry in China was about 2.448 billion yuan, accounting for the 6th in the world; the total output value of the pneumatic industry was about 419 million yuan, accounting for the world’s10 people.2. Current supply and demand profileWith the introduction of technology, independent development and technological transformation, the technical level of the first batch of high-pressure plunger pumps, vane pumps, gear pumps, general hydraulic valves, oil cylinders, oil-free pneumatic components and various types of seals has become remarkable. Improve, and can be stable mass production, provide guarantees for all types of host to improve product quality. In addition, certain achievements have also been made in the aspects of CAD, pollution control, and proportional servo technology for hydraulic pneumatic components and systems, and have been used for production. So far, the hydraulic, pneumatic and seal products have a total of about 3,000 varieties and more than 23,000 specifications. Among them, there are about 1,200 types of hydraulic pressure, more than 10,000 specifications (including 60 types of hydrodynamic products, 500 specifications); about 1350 types of pneumatic, more than 8,000 specifications; there are also 350 types of rubber seals, more than 5000 The specifications are now basically able to adapt to the general needs ofvarious types of mainframe products. The matching rate for major equipment sets can reach more than 60%, and a small amount of exports has started.In 1998, the domestic production of hydraulic components was 4.8 million pieces, with sales of about 2.8 billion yuan (of which mechanical systems accounted for 70%); output of pneumatic components was 3.6 million pieces, and sales were about 550 million yuan (including mechanical systems accounting for about 60%) The production of seals is about 800 million pieces, and the sales volume is about 1 billion yuan (including about 50% of mechanical systems). According to the statistics of the annual report of the China Hydraulic and Pneumatic Sealing Industry Association in 1998, the production and sales rate of hydraulic products was 97.5% (101% of hydraulic power), 95.9% of air pressure, and 98.7% of seal. This fully reflects the basic convergence of production and sales.Although China's hydraulic, pneumatic and sealing industries have made great progress, there are still many gaps compared with the development needs of the mainframe and the world's advanced level, which are mainly reflected in the variety, performance and reliability of products. . Take hydraulic products as an example, the product varieties are only 1/3 of the foreign country, and the life expectancy is 1/2 of that of foreign countries. In order to meet the needs of key hosts, imported hosts, and majortechnical equipment, China has a large number of imported hydraulic, pneumatic, and sealing products every year. According to customs statistics and relevant data analysis, in 1998, the import volume of hydraulic, pneumatic and seal products was about 200 million U.S. dollars, of which the hydraulic pressure was about 140 million U.S. dollars, the pneumatics were 30 million U.S. dollars, and the seal was about 0.3 billion U.S. dollars. The year is slightly lower. In terms of amount, the current domestic market share of imported products is about 30%. In 1998, the total demand for hydraulic parts in the domestic market was about 6 million pieces, and the total sales volume was 4 billion yuan; the total demand for pneumatic parts was about 5 million pieces, and the total sales volume was over 700 million yuan; the total demand for seals was about 1.1 billion yuan. Pieces, total sales of about 1.3 billion yuan. (3) Future developments1. The main factors affecting development(1) The company's product development capability is not strong, and the level and speed of technology development can not fully meet the current needs for advanced mainframe products, major technical equipment and imported equipment and maintenance;(2) Many companies have lagged behind in manufacturing process, equipment level and management level, and their sense of quality is not strong, resulting in low level of product performance, unstable quality,poor reliability, and insufficiency of service, and lack of user satisfaction. And trusted branded products;(3) The degree of professional specialization in the industry is low, the power is scattered, the duplication of the low level is serious, the product convergence between the region and the enterprise leads to blind competition, and the prices are reduced each other, thus the efficiency of the enterprise is reduced, the funds are lacking, and the turnover is difficult. Insufficient investment in development and technological transformation has severely restricted the overall level of the industry and its competitive strength.(4) When the degree of internationalization of the domestic market is increasing, foreign companies have gradually entered the Chinese market to participate in competition, coupled with the rise of domestic private, cooperative, foreign-funded, and individual enterprises, resulting in increasing impact on state-owned enterprises. .2. Development trendWith the continuous deepening of the socialist market economy, the relationship between supply and demand in the hydraulic, pneumatic and sealed products has undergone major changes. The seller market characterized by “shortage” has basically become a buyer’s market characterized by “structured surplus”. Replaced by. From the perspective of overall capacity, it is already in a trend of oversupply, and in particular,general low-grade hydraulic, pneumatic and seals are generally oversupply; and like high-tech products with high technological content and high value and high value-added products that are urgently needed by the host, Can not meet the needs of the market, can only rely on imports. After China's entry into the WTO, its impact may be greater. Therefore, during the “10th Five-Y ear Plan” period, the growth of the industry’s output value must not only rely on the growth of quantity. Instead, it should focus on the structural contradiction of the industry and intensify efforts to adjust the industrial structure and product structure. It should be based on the improvement of quality. Product technology upgrades in order to adapt to and stimulate market demand, and seek greater development.2. Hydraulic application on power slide(1) Introduction of Power Sliding TableUsing the binding force curve diagram and the state space analysis method to analyze and study the sliding effect and the smoothness of the sliding table of the combined machine tool, the dynamics of the hydraulic drive system of the sliding table—the self-regulating back pressure regulating system are established. mathematical model. Through the digital simulation system of the computer, the causes and main influencing factors of the slide impact and the motion instability are analyzed. What kind of conclusions can be drawn from those, if we canreasonably design the structural dimensions of hydraulic cylinders and self-regulating back pressure regulators ——The symbols used in the text are as follows:s 1 - flow source, that is, the flow rate of the governor valve outlet;S el —— sliding friction of the sliding table;R - the equivalent viscous friction coefficient of the slide;I 1 - quality of slides and cylinders;12 - self-adjusting back pressure valve core quality;C 1, c 2 - liquid volume without cylinder chamber and rod chamber;C 2 - Self-adjusting back pressure valve spring compliance;R 1, R2 - Self-adjusting back pressure valve damping orifice fluid resistance;R 9 - Self-adjusting back pressure valve valve fluid resistance;S e2——initial pre-tightening force of self-adjusting back pressure valve spring;I 4, I5 - Equivalent liquid sense of the pipeline;C 5, C 6 - equivalent liquid capacity of the pipeline;R 5, R7 - Equivalent liquid resistance of the pipeline;V 3, V4 - cylinder rodless cavity and rod cavity volume;P 3, P4—pressure of the rodless cavity and rod cavity of the cylinder;F - the slide bears the load;V - speed of slide motion;In this paper, the power bond diagram and the state space splitting method are used to establish the system's motion mathematical model, and the dynamic characteristics of the slide table can be significantly improved.In the normal operation of the combined machine tool, the magnitude of the speed of the slide, its direction and the load changes it undergoes will affect its performance in varying degrees. Especially in the process of work-in-process, the unsteady movement caused by the advancing of the load on the slide table and the cyclical change of the load will affect the surface quality of the workpiece to be machined. In severe cases, the tool will break. According to the requirements of the Dalian Machine Tool Plant, the author used the binding force curve diagram and the state space analysis method to establish a dynamic mathematical model of a self-adjusting back pressure and speed adjustment system for the new hydraulic drive system of the combined machine tool slide. In order to improve the dynamic characteristics of the sliding table, it is necessary to analyze the causes and main influencing factors of the impetus and movement of the sliding table. However, it must pass the computer's digital simulation and the final results obtained from the research.(2) Dynamic Mathematical ModelThe working principle diagram of the self-adjusting back pressure speedregulation system of the combined machine tool slide hydraulic drive system is shown in the figure. This system is used to complete the work-cycle-stop-rewind. When the sliding table is working, the three-position four-way reversing valve is in the illustrated position. The oil supply pressure of the oil pump will remain approximately constant under the effective action of the overflow valve, and the oil flow passes through the reversing valve and adjusts the speed. The valve enters the rodless chamber of the cylinder to push the slide forward. At the same time, the pressurized oil discharged from the rod chamber of the cylinder will flow back to the tank through the self-regulating back pressure valve and the reversing valve. During this process, there was no change in the operating status of both the one-way valve and the relief valve. The complex and nonlinear system of the hydraulic drive system of the self-adjusting back pressure governor system is a kind of self-adjusting back-pressure governor system. To facilitate the study of its dynamic characteristics, a simple and reasonable dynamic mathematical model that only considers the main influencing factors is established. Especially important [1][2]. From the theoretical analysis and the experimental study, we can see that the system process time is much longer than the process time of the speed control valve. When the effective pressure bearing area of the rodless cavity of the fuel tank is large, the flow rate at the outlet of the speed control valve is instantaneous. The overshoot is reflected in thesmall change in speed of the slide motion [2]. In order to further broaden and deeply study the dynamic characteristics of the system so that the research work can be effectively performed on a miniature computer, this article will further simplify the original model [2], assuming that the speed control valve is output during the entire system pass. When the flow is constant, this is considered to be the source of the flow. The schematic diagram of the dynamic model structure of this system is shown in Fig. 2. It consists of a cylinder, a sliding table, a self-adjusting back pressure valve, and a connecting pipe.The power bond graph is a power flow graph. It is based on the transmission mode of the system energy, based on the actual structure, and uses the centralized parameters to represent the role of the subsystems abstractly as a resistive element R, a perceptual element I, and a capacitive element. Three kinds of role of C. Using this method, the physical concept of modeling is clear, and combined with the state-space analysis method, the linear system can be described and analyzed more accurately. This method is an effective method to study the dynamic characteristics of complex nonlinear systems in the time domain. According to the main characteristics of each component of the self-adjusting back pressure control system and the modeling rules [1], the power bond diagram of the system is obtained. The upper half of each key in the figure represents the power flow. The two variables that makeup the power are the force variables (oil pressure P and force F) and the flow variables (flow q and velocity v). The O node indicates that the system is connected in parallel, and the force variables on each key are equal and the sum of the flow variables is zero; 1 The nodes represent the series connection in the system, the flow variables on each key are equal and the sum of the force variables is Zero. TF denotes a transformer between different energy forms. The TF subscripted letter represents the conversion ratio of the flow variable or the force variable. The short bar on the key indicates the causal relationship between the two variables on the key. The full arrow indicates the control relationship. There are integral or differential relationships between the force and flow variables of the capacitive and perceptual elements in the three types of action elements. Therefore, a complex nonlinear equation of state with nine state variables can be derived from Fig. 3 . In this paper, the research on the dynamic characteristics of the sliding table starts from the two aspects of the slide's hedging and the smoothness of the motion. The fourth-order fixed-length Runge-Kutta is used for digital simulation on the IBM-PC microcomputer.(3) Slide advanceThe swaying phenomenon of the slide table is caused by the sudden disappearance of the load acting on the slide table (such as drilling work conditions). In this process, the table load F, the moving speed V, and thepressure in the two chambers of the cylinder P3 and P4 can be seen from the simulation results in Fig. 4. When the sliding table moves at a uniform speed under the load, the oil pressure in the rodless cavity of the oil cylinder is high, and a large amount of energy is accumulated in the oil. When the load suddenly disappears, the oil pressure of the cavity is rapidly reduced, and the oil is rapidly reduced. When the high-pressure state is transferred to the low-pressure state, a lot of energy is released to the system, resulting in a high-speed forward impact of the slide. However, the front slide of the sliding table causes the pressure in the rod cavity of the oil cylinder to cause the back pressure to rise, thereby consuming part of the energy in the system, which has a certain effect on the kicking of the slide table. We should see that in the studied system, the inlet pressure of the self-adjusting back pressure valve is subject to the comprehensive effect of the two-chamber oil pressure of the oil cylinder. When the load suddenly disappears, the pressure of the self-adjusting back pressure valve rapidly rises and stably exceeds the initial back pressure value. It can be seen from the figure that self-adjusting back pressure in the speed control system when the load disappears, the back pressure of the cylinder rises more than the traditional speed control system, so the oil in the rod cavity of the cylinder absorbs more energy, resulting in the amount of forward momentum of the slide It will be about 20% smaller than traditionalspeed control systems. It can be seen from this that the use of self-adjusting back-gear speed control system as a drive system slider has good characteristics in suppressing the forward punch, in which the self-adjusting back pressure valve plays a very large role.(4) The smoothness of the slideWhen the load acting on the slide changes periodically (such as in the case of milling), the speed of the slide will have to fluctuate. In order to ensure the processing quality requirements, it must reduce its speed fluctuation range as much as possible. From the perspective of the convenience of the discussion of the problem, assume that the load changes according to a sine wave law, and the resulting digital simulation results are shown in Figure 5. From this we can see that this system has the same variation rules and very close numerical values as the conventional speed control system. The reason is that when the change of the load is not large, the pressure in the two chambers of the fuel tank will not have a large change, which will eventually lead to the self-regulating back pressure valve not showing its effect clearly.(5) Improvement measuresThe results of the research show that the dynamic performance of a sliding table with self-regulating back pressure control system as a drive system is better than that of a traditional speed control system. To reduce the amount of kick in the slide, it is necessary to rapidly increase the backpressure of the rod cavity when the load disappears. To increase the smoothness of the sliding table, it is necessary to increase the rigidity of the system. The main measure is to reduce the volume of oil. From the system structure, it is known that the cylinder has a large volume between the rod cavity and the oil discharge pipe, as shown in Fig. 6a. Its existence in terms of delay and attenuation of the self-regulating back pressure valve function, on the other hand, also reduces the rigidity of the system, it will limit the further improvement of the propulsion characteristics and the smoothness of the motion. Thus, improving the dynamic characteristics of the sliding table can be handled by two methods: changing the cylinder volume or changing the size of the self-regulating back pressure valve. Through the simulation calculation of the structural parameters of the system and the comparison of the results, it can be concluded that the ratio of the volume V4 between the rod cavity and the oil discharge pipe to the volume V3 between the rodless cavity and the oil inlet pipe is changed from 5.5 to 5.5. At 1 oclock, as shown in the figure, the diameter of the bottom end of the self-adjusting back pressure valve is increased from the original 10mm to 13mm, and the length of the damper triangle groove is reduced from the original lmm to 0.7mm, which will enable the front of the slide table. The impulse is reduced by 30%, the transition time is obviously shortened, and the smoothness of the slide motion will also be greatly improved.中文译文液压系统W Arnold1. 绪论液压站称液压泵站,是独立的液压装置。

附录AHydraulic Brake SystemsWhen you step on the brake pedal,you expect the vehicle to stop.The brake pedal operates a hydraulic that is used for two reasons.First,fluid under pressure can be carried to all parts of the vehicle by small hoses or metal lines without taking up a lot of room of causing routing problems.Second,the hydraulic fluid offers a great mechanical advantage-little foot pressure is required on the pedal, but a great deal of pressure is generated at the wheels.The brake pedal is linked to a piston in the brake master cylinder containing a small piston and a fluid reservoir.Modern master cylinders are actually two separate cylinders.Such a system is called a dual circuit,because the front cylinder is connected to the front brakes and the rear cylinder to the rear brakes.(Some vehicles are connected diagonally). The two cylinders are actually separated,allowing for emergency stopping power should one part of the system fail.The entire hydraulic system from the master cylinder to the wheels is full of hydraulic brake fluid.When the brake pedal is depressed,the piston in the master cylinder are forced to move,exerting tremendous force on the fluid in the lines.The fluid has nowhere to go,and forces the wheel cylinder pistons(drum brakes) or caliper pistons(disc brakes) to exert pressure on the brake shoes or pads.The friction between the brake shoe and wheel drum or the brake pad and rotor (disc) slows the vehiche and eventually stops it.Also attached to the brake pedal si a switch that lights the brake lights as the pedal is depressed.The lights stay on until the brake pedal is released and returns to its normal position.Each wheel cylinder in a drum brake system contains two pistons,one at either end,which push outward in opposite directions.In disc brake systems,the wheel cylinders are part of the caliper (there can be as many as four or as few as one ).Whether disc or drum type,all pistons use some type of rubber seal to preventleakage around the piston,and a rubber dust boot seals the outer of the wheel cylinders against dirt and moisture.When the brake pedal is released,a spring pushes the master cylinder pistons back to their normal positions.Check valves in the master cylinder piston allow fluid to flow toward the wheel cylinders or calipers as the piston returns.Then as the brake shoe return springs pull the brake shoes back to the released position,excess fluid returns to the master cylinder through compensating ports,which have been uncovered as the pistons move back.Any fluid that has leaked from the system will also be replaced through the compensating ports.All dual circuit brake systems use a switch to activate a light,warning of brake failure.The switch si located in a valve mounted near the master cylinder.A piston in the valve reveives pressure on each end from the front and rear brake circuits.When the pressures are balanced,the piston remains stationary,but when one circuit has a leak,greater pressure during the application of the brakes will force the piston to one side or the other,closing the switch and activating the warning light.The light can also be activated by the ignition switch during engine starting or by the parking brake.Front disc,rear drum brake systems also have a metering valve to prevent the front disc brakes from engaging before the rear brakes have contacted the drums.This ensures that the front brakes will not normally be used alone to stop the vehicle.A proportioning valve is also used to limit pressure to the rear brakes to prevent rear wheel lock-up during hard braking.Brake shoes and pads are constructed in a similar.The pad or shoe is composed of a metal backing plate and a priction lining.The lining is either bonded(glued) to the metal,or riveted.Generally,riveted linings provide superior performance,but good quality bonded linings are perfectly adequate.Friction materials will vary between manufacturers and type of pad and the material compound may be referred to as asbestos,organic,semi-metallic,metallic.The difference between these compounds lies in the types and percentages of friction materials used,material binders and performance modifiers.Generally speaking,organic and non-metallic asbestos compound brakes are quiet,easy on rotors and provide good feel.But this comes at the expense of hightemperature operation,so they may not be your best choice for heavy duty use or mountian driving.In most cases,these linings will wear somewhat faster than metallic compound pads,so you will usually replace them more often.But,when using these pads,rotors tend to last longer.Semi-metallic or metallic compound brake linings will vary in performance based on the metallic contents of the compound.Again,generally speaking,the higher the metallic content,the better the friction material will resist heat.This makes them more appropriate for heavy duty applications,but at the expense of braking performance before the pad reaches operating temperature.The first few applications on a cold morning may not give strong braking.Also,metallics and semi-metallics are more likely to squeal,In most cases,metallic compounds last longer than non-metallic pads,but they tend to cause more wear on the rotors.If you use metallic pads,expect to replace the rotors more often.When deciding what type of brake lining is right for you,keep in mind that today’s modern cars have brake materials which are matched to the expected vehicle’s performance capabilities.Changing the material from OEM specification could adversely addect brake feel or responsiveness.Before changing the brake materials,talk to your deaker or parts supplier to help decide what is most appropriate for your application.Remenber that use applications such as towing,stop and go driving,driving down mountain roads,and racing may require a change to a higher performance material.Some more exotic materials are also used in brake linings,among which are Kevlar and carbon compounds.These materials have the capability of extremely good performance for towing,mountain driving or racing.Wear characteristics can be similar to either applications tend to wear like metallic linings,while many of the streetapplications are more like the non-metallics.附录B液压制动系统当踩下制动踏板，您希望该车辆停下。

CHAPTER 3HYDRAULIC FLUIDSDuring the design of equipment that requires fluid power, many factors are considered in selecting the type of system to be used—hydraulic, pneumatic, or a combination of the two. Some of the factors are required speed and accuracy of operation, surrounding atmospheric conditions, economic conditions, availability of replacement fluid, required pressure level, operating temperature range, contamination possibilities, cost of transmission lines, limitations of the equipment, lubricity, safety to the operators, and expected service life of the equipment.After the type of system has been selected, many of these same factors must be considered in selecting the fluid for the system. This chapter is devoted to hydraulic fluids. Included in it are sections on the properties and characteristics desired of hydraulic fluids; types of hydraulic fluids; hazards and safety precautions for working with, handling, and disposing of hydraulic liquids; types and control of contamination; and sampling.PROPERTIESIf fluidity (the physical property of a substance that enables it to flow) and incompressibility were the only properties required, any liquid not too thick might be used in a hydraulic system. However, a satisfactory liquid for a particular system must possess a number of other properties. The most important properties and some characteristics are discussed in the following paragraphs.VISCOSITYViscosity is one of the most important properties of hydraulic fluids. It is a measure of a fluids resistance to flow. A liquid, such as gasoline, which flows easily, has a low viscosity; and a liquid, such as tar, which flows slowly, has a high viscosity. The viscosity of a liquid is affected by changes in temperature and pressure. As the temperature of a liquid increases, its viscosity decreases. That is, a liquid flows more easily when it is hot than when it is cold. The viscosity of a liquid increases as the pressure on the liquid increases.A satisfactory liquid for a hydraulic system must be thick enough to give a good seal at pumps, motors, valves, and so on. These components depend on close fits for creating and maintaining pressure. Any internal leakage through these clearances results in loss of pressure, instantaneous control, and pump efficiency. Leakage losses are greater with thinner liquids (low viscosity). A liquid that is too thin will also allow rapid wearing of moving parts, or of parts that operate under heavy loads. On the other hand, if the liquid is too thick (viscosity too high), the internal friction of the liquid will cause an increase in the liquids flow resistance through clearances of closely fitted parts, lines, and internal passages. This results in pressuredrops throughout the system, sluggish operation of the equipment, and an increase in power consumption.Measurement of ViscosityViscosity is normally determined by measuring the time required for a fixed volume of a fluid (at a given temperature) to flow through a calibrated orifice or capillary tube. The instruments used to measure the viscosity of a liquid are known as viscometers or viscosimeters.Figure 3-1.Saybolt viscometer.Several types of viscosimeters are in use today. The Say bolt viscometer, shown in figure 3-1, measures the time required, in seconds, for 60 milliliters of the tested fluid at 100°F to pass through a standard orifice. The time measured is used to express the fluids viscosity, in Saybolt universal seconds or Saybolt furol seconds.Figure 3-2.Various styles of glass capillary viscometers.The glass capillary viscometers, shown in figure 3-2, are examples of the second type of viscometer used. These viscometers are used to measure kinematic viscosity. Like the Saybolt viscometer, the glass capillary measures the time in seconds required for the tested fluid to flow through the capillary. This time is multiplied by the temperature constant of the viscometer in use to provide the viscosity, expressed in centistokes.The following formulas may be used to convert centistokes (cSt units) to approximate Say bolt universal seconds (SUS units). For SUS values between 32 and 100: SUS SUS cST 195226.0-⨯= For SUS values greater than 100: SUS SUS cST 195220.0-⨯=Although the viscometers discussed above are used in laboratories, there are other viscometers in the supply system that is available for local use. These viscometers can be used to test the viscosity of hydraulic fluids either prior to their being added to a system or periodically after they have been in an operating system for a while.Additional information on the various types of viscometers and their operation can be found in the Physical Measurements Training Manual, NA V AIR 17-35QAL-2.Viscosity IndexThe viscosity index (V.I.) of oil is a number that indicates the effect of temperature changes on the viscosity of the oil. A low V.I. signifies a relatively large change of viscosity with changes of temperature. In other words, the oil becomes extremely thin at high temperatures and extremely thick at low temperatures. On the other hand, a high V.I. signifies relatively little change in viscosity over a wide temperature range.Ideal oil for most purposes is one that maintains a constant viscosity throughout temperature changes. The importance of the V.I. can be shown easily by considering automotive lubricants. Oil having a high V.I. resists excessive thickening when the engine is cold and, consequently, promotes rapid starting and prompt circulation; it resists excessive thinning when the motor is hot and thus provides full lubrication and prevents excessive oil consumption.Another example of the importance of the V.I. is the need for high V.I. hydraulic oil for military aircraft, since hydraulic control systems may be exposed to temperatures ranging from below –65°F at high altitudes to over 100°F on the ground. For the proper operation of the hydraulic control system, the hydraulic fluid must have a sufficiently high V.I. to perform its functions at the extremes of the expected temperature range.Liquids with a high viscosity have a greater resistance to heat than low viscosity liquids which have been derived from the same source. The average hydraulic liquid has a relatively low viscosity. Fortunately, there is a wide choice of liquids available for use in the viscosity range required of hydraulic liquids.The V.I. of an oil may be determined if its viscosity at any two temperatures is known. Tables, based on a large number of tests, are issued by the American Society for Testing and Materials (ASTM). These tables permit calculation of the V.I. from known viscosities.LUBRICATING POWERIf motion takes place between surfaces in contact, friction tends to oppose the motion. When pressure forces the liquid of a hydraulic system between the surfaces of moving parts, the liquid spreads out into a thin film which enables the parts to move more freely. Different liquids, including oils, vary greatly not only in their lubricating ability but also in film strength. Film strength is the capability of a liquid to resist being wiped or squeezed out from between the surfaces when spread out in an extremely thin layer. A liquid will no longer lubricate if the film breaks down, since the motion of part against part wipes the metal clean of liquid.Lubricating power varies with temperature changes; therefore, the climatic and working conditions must enter into the determination of the lubricating qualities of a liquid. Unlike viscosity, which is a physical property, the lubricating power and film strength of a liquid isdirectly related to its chemical nature. Lubricating qualities and film strength can be improved by the addition of certain chemical agents.CHEMICAL STABILITYChemical stability is another property which is exceedingly important in the selection of a hydraulic liquid. It is defined as the liquids ability to resist oxidation and deterioration for long periods. All liquids tend to undergo unfavorable changes under severe operating conditions. This is the case, for example, when a system operates for a considerable period of time at high temperatures.Excessive temperatures, especially extremely high temperatures, have a great effect on the life of a liquid. The temperature of the liquid in the reservoir of an operating hydraulic system does not always indicate the operating conditions throughout the system. Localized hot spots occur on bearings, gear teeth, or at other points where the liquid under pressure is forced through small orifices. Continuous passage of the liquid through these points may produce local temperatures high enough to carbonize the liquid or turn it into sludge, yet the liquid in the reservoir may not indicate an excessively high temperature.Liquids may break down if exposed to air, water, salt, or other impurities, especially if they are in constant motion or subjected to heat. Some metals, such as zinc, lead, brass, and copper, have undesirable chemical reactions with certain liquids.These chemical reactions result in the formation of sludge, gums, carbon, or other deposits which clog openings, cause valves and pistons to stick or leak, and give poor lubrication to moving parts. Once a small amount of sludge or other deposits is formed, the rate of formation generally increases more rapidly. As these deposits are formed, certain changes in the physical and chemical properties of the liquid take place. The liquid usually becomes darker, the viscosity increases and damaging acids are formed.The extent to which changes occur in different liquids depends on the type of liquid, type of refining, and whether it has been treated to provide further resistance to oxidation. The stability of liquids can be improved by the addition of oxidation inhibitors. Inhibitors selected to improve stability must be compatible with the other required properties of the liquid.FREEDOM FROM ACIDITYAn ideal hydraulic liquid should be free from acids which cause corrosion of the metals in the system. Most liquids cannot be expected to remain completely no corrosive under severe operating conditions. The degree of acidity of a liquid, when new, may be satisfactory; but after use, the liquid may tend to become corrosive as it begins to deteriorate.Many systems are idle for long periods after operating at high temperatures. This permits moisture to condense in the system, resulting in rust formation.Certain corrosion- and rust-preventive additives are added to hydraulic liquids. Some of these additives are effective only for a limited period. Therefore, the best procedure is to use the liquid specified for the system for the time specified by the system manufacturer and to protect the liquid and the system as much as possible from contamination by foreign matter, from abnormal temperatures, and from misuse.FLASHPOINTFlashpoint is the temperature at which a liquid gives off vapor in sufficient quantity to ignite momentarily or flash when a flame is applied. A high flashpoint is desirable for hydraulic liquids because it provides good resistance to combustion and a low degree of evaporation at normal temperatures. Required flashpoint minimums vary from 300°F for the lightest oils to 510°F for the heaviest oils.FIRE POINTFire point is the temperature at which a substance gives off vapor in sufficient quantity to ignite and continue to burn when exposed to a spark or flame. Like flashpoint, a high fire point is required of desirable hydraulic liquids.MINIMUM TOXICITYToxicity is defined as the quality, state, or degree of being toxic or poisonous. Some liquids contain chemicals that are a serious toxic hazard. These toxic or poisonous chemicals may enter the body through inhalation, by absorption through the skin, or through the eyes or the mouth. The result is sickness and, in some cases, death. Manufacturers of hydraulic liquids strive to produce suitable liquids that contain no toxic chemicals and, as a result, most hydraulic liquids are free of harmful chemicals. Some fire-resistant liquids are toxic, and suitable protection and care in handling must be provided.DENSITY AND COMPRESSIBILITYA fluid with a specific gravity of less than 1.0 is desired when weight is critical, although with proper system design, a fluid with a specific gravity greater than one can be tolerated. Where avoidance of detection by military units is desired, a fluid which sinks rather than rises to the surface of the water is desirable. Fluids having a specific gravity greater than 1.0 are desired, as leaking fluid will sink, allowing the vessel with the leak to remain undetected.Recall from chapter 2 that under extreme pressure a fluid may be compressed up to 7 percent of its original volume. Highly compressible fluids produce sluggish system operation. This does not present a serious problem in small, low-speed operations, but it must be considered in the operating instructions.FOAMING TENDENCIESFoam is an emulsion of gas bubbles in the fluid. Foam in a hydraulic system results fromcompressed gases in the hydraulic fluid. A fluid under high pressure can contain a large volume of air bubbles. When this fluid is depressurized, as when it reaches the reservoir, the gas bubbles in the fluid expand and produce foam. Any amount of foaming may cause pump cavitations and produce poor system response and spongy control. Therefore, defaming agents are often added to fluids to prevent foaming. Minimizing air in fluid systems is discussed later in this chapter.CLEANLINESSCleanliness in hydraulic systems has received considerable attention recently. Some hydraulic systems, such as aerospace hydraulic systems, are extremely sensitive to contamination. Fluid cleanliness is of primary importance because contaminants can cause component malfunction, prevent proper valve seating, cause wear in components, and may increase the response time of servo valves. Fluid contaminants are discussed later in this chapter.The inside of a hydraulic system can only be kept as clean as the fluid added to it. Initial fluid cleanliness can be achieved by observing stringent cleanliness requirements (discussed later in this chapter) or by filtering all fluid added to the system.TYPES OF HYDRAULIC FLUIDSThere have been many liquids tested for use in hydraulic systems. Currently, liquids being used include mineral oil, water, phosphate ester, water-based ethylene glycol compounds, and silicone fluids. The three most common types of hydraulic liquids are petroleum-based, synthetic fire-resistant, and water-based fire-resistant.PETROLEUM-BASED FLUIDSThe most common hydraulic fluids used in shipboard systems are the petroleum-based oils. These fluids contain additives to protect the fluid from oxidation (antioxidant), to protect system metals from corrosion (anticorrosion), to reduce tendency of the fluid to foam (foam suppressant), and to improve viscosity.Petroleum-based fluids are used in surface ships，electro hydraulic steering and deck machinery systems, submarines，hydraulic systems, and aircraft automatic pilots, shock absorbers, brakes, control mechanisms, and other hydraulic systems using seal materials compatible with petroleum-based fluids.SYNTHETIC FIRE-RESISTANT FLUIDS Petroleum-based oils contain most of the desired properties of a hydraulic liquid. However, they are flammable under normal conditions and can become explosive when subjected to high pressures and a source of flame or high temperatures. Nonflammable synthetic liquids have been developed for use in hydraulic systems where fire hazards exist.Phosphate Ester Fire-Resistant FluidPhosphate ester fire-resistant fluid for shipboard use is covered by specification MIL- H-19457. There are certain trade names closely associated with these fluids. However, the only acceptable fluids conforming to MIL-H-19457 are the ones listed on the current Qualified Products List (QPL) 19457. These fluids will be delivered in containers marked MIL-H-19457C or a later specification revision. Phosphate ester in containers marked by a brand name without specification identification must not be used in shipboard systems, as they may contain toxic chemicals.These fluids will burn if sufficient heat and flame are applied, but they do not support combustion. Drawbacks of phosphate ester fluids are that they will attack and loosen commonly used paints and adhesives, deteriorate many types of insulations used in electrical cables, and deteriorate many gasket and seal materials. Therefore, gaskets and seals for systems in which phosphate ester fluids are used are manufactured of specific materials. Naval Ships，Technical Manual, chapter 262, specifies paints to be used on exterior surfaces of hydraulic systems and components in which phosphate ester fluid is used and on ship structure and decks in the immediate vicinity of this equipment. Naval Ships，Technical Manual, chapter 078, specifies gasket and seal materials used. NA V AIR 01-1A-17 also contains a list of materials resistant to phosphate ester fluids.Trade names for phosphate ester fluids, which do not conform to MIL-H-19457 include Pydraul、Skydrol、and Fire Safe.PHOSPHATE ESTER FLUID SAFETY.—as a maintenance person, operator, supervisor, or crew member of a ship, squadron, or naval shore installation, you must understand the hazards associated with hydraulic fluids to which you may be exposed.Phosphate ester fluid conforming to specification MIL-H-19457 is used in aircraft elevators, ballast valve operating systems, and replenishment-at-sea systems. This type of fluid contains a controlled amount of neurotoxic material. Because of the neurotoxic effects that can result from ingestion, skin absorption, or inhalation of these fluids, be sure to use the following precautions:1. Avoid contact with the fluids by wearing protective clothing.2. Use chemical goggles or face shields to protect your eyes.3. If you are expected to work in an atmosphere containing a fine mist or spray, wear a continuous-flow airline respirator.4. Thoroughly clean skin areas contaminated by this fluid with soap and water.5. If you get any fluid in your eyes, flush them with running water for at least 15 minutes and seek medical attention.If you come in contact with MIL-H-19457 fluid, report the contact when you seek medical aid and whenever you have a routine medical examination.Naval Ships，Technical Manual, chapter 262, contains a list of protective clothing, along with national stock numbers(NSN),for use with fluids conforming to MIL-H-19457.It also contains procedures for repair work and for low-level leakage and massive spills cleanup.PHOSPHATE ESTER FLUID DISPOSAL.—Waste MIL-H-19457 fluids and refuse (rags and other materials) must not be dumped at sea. Fluid should be placed in bung-type drums. Rags and other materials should be placed in open top drums for shore disposal. These drums should be marked with a warning label stating their content, safety precautions, and disposal instructions. Detailed instructions for phosphate ester fluids disposal can be found in Naval Ships, Technical Manual, chapter 262, and OPNA VINST 5090.1.Silicone Synthetic Fire-Resistant FluidsSilicone synthetic fire-resistant fluids are frequently used for hydraulic systems which require fire resistance, but which have only marginal requirements for other chemical or physical properties common to hydraulic fluids. Silicone fluids do not have the detrimental characteristics of phosphate ester fluids, nor do they provide the corrosion protection and lubrication of phosphate ester fluids, but they are excellent for fire protection. Silicone fluid conforming to MIL-S-81087 is used in the missile hold-down and lockout system aboard submarines.Lightweight Synthetic Fire-Resistant Fluids In applications where weight is critical, lightweight synthetic fluid is used in hydraulic systems. MIL-H-83282 is a synthetic, fire-resistant hydraulic fluid used in military aircraft and hydrofoils where the requirement to minimize weight dictates the use of a low-viscosity fluid. It is also the most commonly used fluid in aviation support equipment. NA V AIR 01-1A-17 contains additional information on fluids conforming to specification MIL-H-83282.WATER-BASED FIRE-RESISTANT FLUIDS The most widely used water-based hydraulic fluids may be classified as water-glycol mixtures and water-synthetic base mixtures. The water-glycol mixture contains additives to protect it from oxidation, corrosion, and biological growth and to enhance its load-carrying capacity.Fire resistance of the water mixture fluids depends on the vaporization and smothering effect of steam generated from the water. The water in water-based fluids is constantly being driven off while the system is operating. There- fore, frequent checks to maintain the correct ratio of water are important.The water-based fluid used in catapult retracting engines, jet blast deflectors, and weapons elevators and handling systems conforms to MIL-H-22072.The safety precautions outlined for phosphate ester fluid and the disposal of phosphate ester fluid also apply to water-based fluid conforming to MIL-H-22072.CONTAMINATIONHydraulic fluid contamination may be described as any foreign material or substance whose presence in the fluid is capable of adversely affecting system performance or reliability. It may assume many different forms, including liquids, gases, and solid matter of various compositions, sizes, and shapes. Solid matter is the type most often found in hydraulic systems and is generally referred to as particulate contamination. Con- termination is always present to some degree, even in new, unused fluid, but must be kept below a level that will adversely affect system operation. Hydraulic contamination control consists of requirements, techniques, and practices necessary to minimize and control fluid contamination.CLASSIFICATIONThere are many types of contaminants which are harmful to hydraulic systems and liquids. These contaminants may be divided into two different classes—particulate and fluid.Particulate ContaminationThis class of contaminants includes organic, metallic solid and inorganic solid contaminants. These contaminants are discussed in the following paragraphs.ORGANIC CONTAMINATION.—Organic solids or semisolids found in hydraulic systems are produced by wear, oxidation, or polymerization. Minute particles of O-rings, seals, gaskets, and hoses are present, due to wear or chemical reactions. Synthetic products, such as neoprene, silicones, and hypalon, though resistant to chemical reaction with hydraulic fluids, produce small wear particles. Oxidation of hydraulic fluids increases with pressure and temperature, although antioxidants are blended into hydraulic fluids to minimize such oxidation.The ability of a hydraulic fluid to resist oxidation or polymerization in service is defined as its oxidation stability. Oxidation products appear as organicacids,asphaltics,gums,and varnishes. These products combine with particles in the hydraulic fluid to form sludge. Some oxidation products are oil soluble and cause the hydraulic fluid to increase in viscosity; other oxidation products are not oil soluble and form sediment.METALLIC SOLID CONTAMINATION.—Metallic contaminants are almost always present in a hydraulic system and will range in size from microscopic particles to particles readily visible to the naked eye. These particles are the result of wearing and scoring of bare metal parts and plating materials, such as silver and chromium. Although practically all metals commonly used for parts fabrication and plating may be found in hydraulic fluids, themajor metallic materials found are ferrous, aluminum, and chromium particles. Because of their continuous high-speed internal movement, hydraulic pumps usually contribute most of the metallic particulate contamination present in hydraulic systems. Metal particles are also produced by other hydraulic system components, such as valves and actuators, due to body wear and the chipping and wearing away of small pieces of metal plating materials.INORGANIC SOLID CONTAMINATION.—This contaminant group includes dust, paint particles, dirt, and silicates. Glass particles from glass bead penning and blasting may also be found as contaminants. Glass particles are very undesirable contaminants due to their abrasive effect on synthetic rubber seals and the very fine surfaces of critical moving parts. Atmospheric dust, dirt, paint particles, and other materials are often drawn into hydraulic systems from external sources. For example, the wet piston shaft of a hydraulic actuator may draw some of these foreign materials into the cylinder past the wiper and dynamic seals, and the contaminant materials are then dispersed in the hydraulic fluid. Contaminants may also enter the hydraulic fluid during maintenance when tubing, hoses, fittings, and components are disconnected or replaced. It is therefore important that all exposed fluid ports be sealed with approved protective closures to minimize such contamination.Fluid ContaminationAir, water, solvent,and other foreign fluids are in the class of fluid contaminants.AIR CONTAMINATION.—Hydraulic fluids are adversely affected by dissolved, entrained, or free air. Air may be introduced through improper maintenance or as a result of system design. Any maintenance operation that involves breaking into the hydraulic system, such as disconnecting or removing a line or component will invariably result in some air being introduced into the system. This source of air can and must be minimized by prebilling replacement components with new filtered fluid prior to their installation. Failing to prefill a filter element bowl with fluid is a good example of how air can be introduced into the system. Although prebilling will minimize introduction of air, it is still important to vent the system where venting is possible.Most hydraulic systems have built-in sources of air. Leaky seals in gas-pressurized accumulators and reservoirs can feed gas into a system faster than it can be removed, even with the best of maintenance. Another lesser known but major source of air is air that is sucked into the system past actuator piston rod seals. This usually occurs when the piston rod is stroked by some external means while the actuator itself is not pressurized.WATER CONTAMINATION.—Water is a serious contaminant of hydraulic systems. Hydraulic fluids are adversely affected by dissolved, emulsified, or free water. Water contamination may result in the formation of ice, which impedes the operation of valves,actuators, and other moving parts. Water can also cause the formation of oxidation products and corrosion of metallic surfaces.SOLVENT CONTAMINATION.—Solvent contamination is a special form of foreign fluid contamination in which the original contaminating substance is a chlorinated solvent. Chlorinated solvents or their residues may, when introduced into a hydraulic system, react with any water present to form highly corrosive acids.Chlorinated solvents, when allowed to combine with minute amounts of water often found in operating hydraulic systems, change chemically into hydrochloric acids. These acids then attack internal metallic surfaces in the system, particularly those that are ferrous, and produce a severe rust-like corrosion. NA V AIR 01-1A-17 and NSTM, chapter 556, contain tables of solvents for use in hydraulic maintenance.FOREIGN-FLUIDS CONTAMINATION.—Hydraulic systems can be seriously contaminated by foreign fluids other than water and chlorinated solvents. This type of contamination is generally a result of lube oil, engine fuel, or incorrect hydraulic fluid being introduced inadvertently into the system during servicing. The effects of such contamination depend on the contaminant, the amount in the system, and how long it has been present.NOTE: It is extremely important that the different types of hydraulic fluids are not mixed in one system. If different type hydraulic fluids are mixed, the characteristics of the fluid required for a specific purpose are lost. Mixing the different types of fluids usually will result in a heavy, gummy deposit that will clog passages and require a major cleaning. In addition, seals and packing installed for use with one fluid usually are not compatible with other fluids and damage to the seals will result.ORIGIN OF CONTAMINATIONRecall that contaminants are produced from wear and chemical reactions, introduced by improper maintenance, and inadvertently introduced during servicing. These methods of contaminant introduction fall into one of the four major areas of contaminant origin.1. Particles originally contained in the system. These particles originate during the fabrication and storage of system components. Weld spatter and slag may remain in welded system components, especially in reservoirs and pipe assemblies. The presence is minimized by proper design. For example, seam-welded overlapping joints are preferred, and arc welding of open sections is usually avoided. Hidden passages in valve bodies, inaccessible to sand blasting or other methods of cleaning, are the main source of introduction of core sand. Even the most carefully designed and cleaned castings will almost invariably free some sand particles under the action of hydraulic pressure. Rubber hose assemblies always contain some loose particles. Most of these particles can be removed by flushing the hose before installation;。

附录A译文随车液压起重机的控制摘要：本文主要是描述随车液压起重机的控制过程。

这篇论文分为五个部分：需求分析，液压系统以及存在的问题的分析，不同结构产生不同问题的分析，基于更加先进复杂电液比例控制阀的新技术的发展趋势的分析。

本文的研究工作是和实际的工业相结合的，比纯粹的研究理论更有意义。

关键字：随车液压起重机，控制策略，电液比例控制阀1.引言本文主要叙述的是对随车起重机控制系统的改进方法随车汽车起重机可以看成是一种大型柔性控制机械结构。

这种控制系统把操作人员的命令由机械结构变为执行动作。

这样定义这种控制系统是为了避免在设计它事产生模糊的思想这是一种通过人的命令把能量转化成机械动作的控制系统。

本文所写的就是这种控制系统。

以这个目标为指导方针来分析怎样设计出新的控制系统。

文章分为五个部分：1.分析这种控制系统必须据有易操作性，高强度，高效性，稳定性，安全性。

2.分析目前这种操作系统所存在的问题。

3.从不同的方面分析这种控制系统：不同的操作方式，不同的控制方法，不同的组织结构。

4.介绍一种适合于未来工业的比较经济的新的控制系统。

5.分析一种据有高性能，高效率，易控制等的比较好的控制系统。

它将成为今后研究的比较经济高效的一种方案。

2.论文部分2.1对控制系统必备条件的分析在一种新的操作系统开始正式投入工作之前，对这种控制系统据有严格的要求。

对控制系统的影响有很多因素。

例如：机械结构的可实行性因素，可操作性因素，效率因素，符合工业标准。

工业需求必须放在第一位。

这与在控制系统中导管破裂保护和超载保护有同等的地位。

其次稳定性要求也很重要；系统不稳定就没法正常工作。

一旦稳定性要求得以确定，控制系统性能要求就可以进一步确定。

机械结构决定了起重机的可操作性。

机械机构是随车起重机中可以往复转动固有频率低的大型柔性结构。

为了防止起重机振动，必须使起重机在固有频率下工作，或者提高起重机的固有频率。

如果它的固有频率太低或者太高，操作人员将无法给它进行操作。

Original AbstractHydraulic lifting platform is a versatile crane lifting equipment, widely used in factories, docks, construction, transportation, sports, equipment maintenance and other high-altitude operations and maintenance. Existing hydraulic lifting platform there are many, can be roughly divided into: four-wheel mobile lifting platform, push-type lift platform, car load lifting platform, fixed platform lift, scissor lift platform, four-post lift The two column lift and so on.In recent years, with the rapid increase in the use of cars, China's booming auto industry, especially the car industry. This makes the auto repair industry has grown, demand for automotive maintenance equipment rapid expansion, but also the maintenance requirements in the automotive tools and equipment requirements on the increasingly high lift vehicle repair workshop is essential and most important maintenance machinery and equipment. The role of auto lift car is in need of repair, a smooth upgrade to the appropriate height, so that maintenance workers at the bottom of the car chassis maintenance and inspection. Generally divided into high column car lift and scissors. Either way, are required to meet the synchronous lifting the car, cornering can not happen, and asked for the empty chassis bottom for easy maintenance workers for maintenance work which requires lifting platform synchronous lifting, running smoothly. Therefore, maintenance of the car lifting platform equipment is generally driven by hydraulic system.With the expanding service sector, as well as the further development of automation, the maintenance staff to reduce labor intensity, making the easy maintenance, and can better improve the efficiency of vehicle maintenance, and car maintenance service quality, so the hydraulic lift Platform automation requirements are also rising. Vehicle maintenance is currently required to meet the synchronization control, lifting the platform lift system depends mainly on the hydraulic system and electrical control and drive systems, but the lift platform is currently owned by the widespread leakage, internal leakage, short life, the operation not flexible, synchronous operation and low defects. To avoid these disadvantages, require more precise synchronization to ensure that the hydraulic lifting platform lift precision, and now most of the hydraulic lifting platform simultaneously phasing out all traditional hydraulic valves, the use of more precise control of the new electro-hydraulic servo valve, electro-hydraulic proportional digital electro-hydraulic valve and valve to control the hydraulic system, to achieve synchronization and high precision. As a form of electro-hydraulic proportional valve type of diverse, easy to use composition of a variety of electrical and computer-controlled hydraulic system, control of high precision, installation flexibility and strong anti-pollution and many other advantages.Currently used in the automotive repair Hydraulic synchronous lift platform vehicle maintenance plays an important role in synchronous lifting platform on a variety of hydraulic valves, hydraulic cylinders, hydraulic pump station innovation and improvement, making a hydraulic lifting platform synchronization smoothrunning, low noise, fast response, high precision synchronization of the repair and maintenance in the car played a crucial role.With the hydraulic lift platform in the automotive repair industry, application and further improvement and innovation in the maintenance of hydraulic lifting platform has the car can achieve more complex functions, the structure of the platform, drive on, and a variety of control systems, has been greatly improved. The current lift platform lift system is mainly driven by the hydraulic system, of course, do not rely on hydraulic pressure, as well as dual-use diesel electric rotary lift platform, now appeared battery driven lift platform, continuously variable transmission can be achieved with safer, more convenient and low noise advantages. Lifting platform is currently widespread leakage, internal leakage, short life, the operation is not flexible, synchronous operation and low defects. To avoid these disadvantages, require more precise synchronization to ensure that the hydraulic lifting platform lift precision, and now most of the hydraulic lifting platform simultaneously phasing out all traditional hydraulic valves, the use of more precise control of the new electro-hydraulic servo valve, electro-hydraulic proportional digital electro-hydraulic valve and valve to control the hydraulic system, to achieve synchronization and high precision. As a form of electro-hydraulic proportional valve type of diverse, easy to use composition of a variety of electrical and computer-controlled hydraulic system, control of high precision, installation flexibility and strong anti-pollution and many other advantages, applications become increasingly broadened.In China, although synchronous hydraulic lifting platform for such development, production started late, but with China's rapid economic development, in order to adapt to China in various fields used by the synchronous hydraulic lifting platform development needs and take the large-scale, standardized , intensive, product support services, achieving mechanical, electrical, fluid integration platform in the application of synchronous movements. The use of synchronous hydraulic lifting platform surface, the service has been expanding, is now in rapid development stage, and now hydraulic lifting platform reliability, security, easy operation and simple directness, and other aspects greatly improved, and with the the popularity and development of computer and mechanical, electrical, fluid integration progress of the study, major domestic and foreign companies have to compete with the computer (electronic) control system to improve overall performance and reduce the use of hydraulic components, machine, reducing the whole size and weight, improve the sensitivity of control and synchronization accuracy. In particular, the manufacturers actively introducing and digesting foreign advanced technology, development of new varieties, improving product technology and quality level, has been part of the hydraulic lifting platform synchronized at or close to the international level of similar products.Currently used in the automotive repair Hydraulic synchronous lift platform vehicle maintenance plays an important role in synchronous lifting platform on a variety of hydraulic valves, hydraulic cylinders, hydraulic pump station innovation and improvement, making a hydraulic lifting platform synchronization Smooth running, low noise, fast response, high precision synchronization, for the repair and maintenance of the car plays an irreplaceable role in a wide range prospects.Therefore, the lifting platform for further research and improvement, optimize system performance and structure to further improve to make up for the shortcomings of existing technology has important significance.The subject of the design of the hydraulic lifting platform main use of theoretical research and design, through the understanding and study of the hydraulic system, as well as existing control technologies and more in-depth research and development, in the hydraulic system components and further understanding and learning , Combined with the modernization of hydraulic components and automation and control components within the hydraulic control through traditional high-tech components and control elements of existing comparative and comprehensive application of the traditional hydraulic system, based on the research and design more innovative set of machines , Electricity, liquid in one of the hydraulic control system, makes the system more stable and faster to achieve the advantages.Hydraulic lift platform system, requires the ability to achieve four-wheeled vehicles in a controlled synchronous lifting height lifting range, to achieve safe and reliable control of the two front, two rear, two revolvers, two rounds of synchronous lifting the right and to ensure synchronous movements accuracy. The hydraulic lift system also must have a fast response speed, hydraulic power units, small size, compact structure, large power weight ratio, ease of manipulation and control, labor-saving convenience and easy to implement automated, with overload protection for high reliability requirements system, excellent technical performance, while ensuring synchronous hydraulic lifting platform can be anywhere in the vertical direction on a longer time (60 min or longer) within a reliable locking, the system can work continuously and reliably, the system energy efficient, easy to maintain low cost. Hydraulic lift platform to meet system design requirements, synchronous movements smooth, and the design to achieve the functional requirements, develop the system closed-loop control of hydraulic systems, hydraulic systems used to satisfy the synchronization requirements of precision and control to achieve the four-wheeled vehicles in a controlled synchronous lifting height lifting range, to achieve safe and reliable control of the two front, two rear, two revolvers, two rounds of synchronous lifting the right and to ensure the accuracy of synchronous movements.To meet the synchronous lifting hydraulic system, the system needs to have synchronization control device to achieve synchronization. Synchronization of hydraulic system is currently running multiple control methods, mainly mechanical synchronization method, pump or motor parallel method, double rod cylinder in series, control valve, synchronizer, synchronization control valve circuit, servo and so on.According to the design of machinery and equipment requirements for the realization of a better two-car front-wheel, two rear, two revolvers, two synchronous lifting the right wheel, respectively, the flexible control, the design of the four hydraulic cylinders used for its intended to achieve their respective parts of the wheel lift and flexible control. Synchronization to achieve higher accuracy and more flexible control, the design does not use the traditional control valves to control, but intends to adopt more new electro-hydraulic proportional control valve to control. Electro-hydraulic proportional control valve is between the ordinary hydraulic valveand servo valve between a fluid control valves, servo valves with similar functions, but also has its specific advantages. Proportional solenoid valve is replaced by the proportion of ordinary hydraulic valve adjustment and control devices and form, it can be given input voltage or current signal proportional continuous, remote control of the direction of flow, pressure and flow. Reasonable use of electro-hydraulic proportional control valve can improve the automation and accuracy, and simplify the system. Commonly used proportional valve can be divided into: proportional pressure valve, proportional flow valves and proportional directional valve three.The design uses electro-hydraulic proportional control system, closed-loop feedback control system, the detection by the sensor and fed back through the electro-hydraulic proportional plc valve, electro-hydraulic proportional control valve opening size corresponding to the achievement of the hydraulic cylinder to achieve synchronous lifting control accuracy. To ensure the hydraulic cylinder to achieve at work to ensure self-locking, hydraulic system should be in each cylinder fuel supply system with check valve to achieve self-lock function to ensure the safety of hydraulic lifting platform. Overload protection to ensure the realization of the hydraulic system, hydraulic system relief valve in the hydraulic pump that needs to be installed to ensure the safety of the system to provide a certain pressure. Oil to the system to meet the system requirements to run and quality of hydraulic oil, hydraulic system should be in the inlet and outlet port to install filters. In order to meet the hydraulic system can be fully automated, the system of hydraulic directional control valve solenoid valve are used. In order to better respond to energy problems, you can, where necessary, instead of using the accumulator motor-driven pump provides the pressure accumulator to provide the direct use of the hydraulic cylinder pressure to meet the relevant sport.In order to achieve self-locking hydraulic cylinder to the function of the hydraulic system in the bottom of each cylinder are equipped with check valve, check valve can achieve one-way self-locking, two-way communication function of the oil. In order to provide security to meet the hydraulic system pressure, not suddenly as high pressure hydraulic system of the adverse effects or even damage some of the hydraulic components, so as a safety valve with pressure relief valve to prevent hydraulic overload protection. In order to achieve automation of the hydraulic system to meet the simultaneous operation of the system is more accurate, and the realization of the system's high efficiency, rapid response requirements, the use of electro-hydraulic proportional directional control valve to high precision, fast response to the synchronization control. Most of the traditional manual control valve, which controlled comparison machinery, it is difficult to achieve automation. Electromagnetic valve, use the pull solenoid valve to control the direction of control of the commutation circuit to achieve better automated results. Shunt valve assembly, also known as synchronous valve, is a hydraulic diversion valve, valve functions in one set of the independent hydraulic device. Shunt valve synchronization is the set speed sync, that is, when two or more cylinders cylinder under different loads, respectively, the shunt valve set pressure and flow through the sensitive internal components automatically adjust the fuel tank of exercise to maintain synchronization.Shunt valve assembly is mainly used in multi-cylinder hydraulic cylinder and the synchronization control system. Split set by the synchronous control flow valve hydraulic system has a simple structure, low cost, design, sets, debugging and ease of use, reliability and many other advantages, which shunt valve assembly in the hydraulic system has been widely used, so there will also be a reasonable set of flow diversion valve used to achieve simultaneous control of two hydraulic cylinders. In the hydraulic system, the oil cleanliness of the normal operation of the hydraulic system has a vital role, so the oil pump and fuel tank return port port filters have been installed in order to ensure that the cleaning fluid degrees, which is an indispensable circuit hydraulic system attachment.In this system, due to the beneficial effects of gravity, the decline in the course of lifting platform, you can completely rely on gravity to provide power, where only one-way valve on the hydraulic control valve port for remote control of the pressure to provide, in under the action of gravity to allow check valve can be decreased to achieve oil return channel, as the pressure is not big, so no need to re-use of oil pump drive motors to achieve the check valve through the oil pressure can be used directly to provide the pressure accumulator, so the treatment, not only simplifies the system control, and can better save energy and avoid frequent start the motor, can effectively extend the life of the motor and pump, and to improve the efficient use of the hydraulic system, which can be said that the biggest advantage of the system design.Hydraulic platform of exercise is to achieve the various hydraulic cylinders rise and fall, but the rise and fall during the lifting phase will be a period in the acceleration of movement, until the required speed to the speed, the platform will achieve a uniform motion and then decelerate to stop. Throughout the campaign process, the hydraulic lifting platform mainly by the external load platform of the car's own weight of gravity and composition. Therefore, the size of the external load is relatively stable and unchanging, and only in the acceleration phase of operation of the entire platform will have a maximum load.Hydraulic lifting platform synchronized variety of mechanical structure, a four-wheel mobile lifting platform, elevating platform vehicle-mounted, fixed landing platform, sets of cylinder-type lift platform, four-column lifting platform, the two-column lifting platform, scissor Lifting platform, and other mechanical structure, and mechanical structure of different ways to achieve different movements to meet the different, specific ways of working and working environment.The design of synchronous hydraulic lifting platform is designed to meet the car repair industry in the use of lifting platform. Maintenance workers to consider maintenance when the car convenient and comfortable, you need to lift the car a certain height, but such use conditions, most of the requirements of hydraulic lifting platform is fixed, so the fixed hydraulic lift platform. While the four cylinder design can be fixed in the foundation, and to consider their own characteristics and the hydraulic cylinder the height, you can dig a pit in the maintenance shop type of foundation, the four cylinder bolts to fully firmly fixed to the ground by on. In order to be able to check and repair chassis, hydraulic lifting platform not designed for the whole plate fixed on the hydraulic cylinder in the bottom four shelves, is thoughtful, Idesigned the mechanical structure to meet the four-wheel placed in the middle hollow of the platform structure, so that not only meet the maintenance requirements, but also save a portion of material, making the structure more simple and beautiful. Taking into account the car body as a whole if there is a need to use floating platform from the condition, for example, remove the wheels need repair or need to dress up tires, etc., are required to meet all hold up the whole body, this, this design in each set of two plates of another set of lifting devices, lifting devices to facilitate use of the vehicle chassis will hold up, to achieve overall body vacant. To consider the overall open on the car platform, hold up the car fixed and plate lifting devices, and can be used scissor lift to reach the level of a structure. The biggest advantage of using this structure is not hold up in the chassis to the plate when retracted within this structure, so that the overall structure is beautiful and practical. To meet the car on the platform do not slip and stable place on the platform, placed on the plate anti-slip skid plate.Programmable Logic Controller (PLC) is an industrial control computer, is the succession of computer, automatic control technology and communication technology as one of the new automatic device. It has strong anti-interference ability, low price, reliability, programming is simple, easy to use and so on, in the industrial field operators by the likes of engineering, so PLC in all areas of industrial control is widely used.The design is based on the ratio of the hydraulic cylinder piston rod valve position control system, namely the use of PLC control signal generated by electro-hydraulic proportional valve driver to control the exact location of the hydraulic cylinder. Hydraulic cylinder piston rod displacement sensor displacement feedback signal output by the A / D converted into digital signals into the computer, the PLC signals within a given comparison, and the control algorithm according to the set after the output control signal, after D / A converted to analog voltage or current signal proportional electro-hydraulic control valve spool position to control the flow of the hydraulic cylinder transmission, drive hydraulic cylinder, to achieve the position of the piston with a load control system as a whole constitute a closed-loop control for precise positioning .原文摘要液压升降平台是一种多功能起重升降设备，广泛应用于工厂、码头、建筑、交通、体育馆、设备检修等高空作业及维修。

中英文对照起重机术语大全起重机（crane）moblie crane 移动式起重机truck crane 汽车式起重机wheel crane / wheeled crane 轮胎起重机crawler crane / caterpillar crane 履带吊;履带式起重机tower crane 塔吊; 塔式起重机-construction tower cranes / building tower crane 建筑塔式起重机，建筑塔机-luffing jib tower crane 动臂塔式起重机-tower jib crane 塔式挺杆起重机（含义与上同）bridge crane/traveling crane/overhead crane 桥吊；桥式吊车; 桥式起重机-electric traveling crane 电动桥式起重机（俗称行车、天车）-electric double-beam bridge crane 电动双梁桥式起重机portal crane / portal bridge crane门式起重机- semi-goliath crane 半门式起重机- semi-portal bridge crane 半龙门起重机gantry cranes 龙门起重机- rubber tyred gantry crane 轮胎式龙门吊- electric gantry crane 电动龙门式起重机- hook gantry crane 吊钩龙门吊- economical gantry crane 简单龙门起重机; 简易龙门起重机- rubber tyred container gantry crane 轮胎式集装箱龙门起重机barges / floating Cranes 船式起重机; 浮吊; 浮式起重机水上起重机boom crane 吊杆起重机; 桁梁起重机; 臂式起重机; 伸臂起重机bucket crane 料罐起重机; 吊斗起重机building crane 建筑起重机cable crane 索道起重机; 缆索起重机container crane 集装箱起重机electric crane 电动吊车; 电动起重机; 电力起重机electriomagnet crane 电磁铁起重机electric jib crane 电动单臂起重机fixed crane 固定式起重机climbing crane 爬升式起重机；攀爬式起重机fixed derrick crane 固定式动臂起重机fixed jib crane 固定式悬臂起重机flying crane helicopter 起重直升机hoist crane 起重葫芦hoisting crane 升降起重机hook type crane 钩式起重机twin hood crane 双钩吊车mobile crane 移动式吊车; 移动式起重机quay crane 码头起重机; 码头桥式起重机; 港岸起重机revolving track crane 回转式轨道起重机circular crane 旋转式吊车环形吊车roof crane 屋顶起重机transporter crane 桁架式起重机electric crane 电动吊车; 电动起重机gasoline crane 汽油起重机hydraulic crane 液力起重机; 液压起重机derrick crane 人字扒杆人字起重机-travelling derrick crane 移动式人字扒杆jib crane / cantilever crane 悬臂式起重机wall crane 壁式起重机heavy duty crane 重型起重机crane output / carrying capacity of crane / lifting capacity of crane 吊车起重能力crane load 起重机起重量; 起重机起重量crane rating 起重机定额; 起重机载重量crane radius 起重机起吊半径; 起重机伸臂活动半径; 起重机伸距craneage 吊车工时crane beam 行车梁起重机大梁crane stair 起重机楼梯hoist drive mechanism 起重机驱动机构travelling crab 起重机小车hoisting controller 起重控制器吊车控制手柄hoisting facility 起重设施lifting gear 起重装置crane (runway) girder 吊车梁crane support wall 吊车支承墙crane boom 起重机吊架; 起重架; 吊车臂; 吊车起重扒杆; 吊杆crane column 吊车柱crane hook / grab （or lift hook）（ or dolly）起重机吊钩crane jib 起重机吊杆crane bridge 起重机桥crane buffer 吊车缓冲器crane rope / crane cable起重钢绳; 起重机吊索; 吊车钢丝绳crane carriage 起重小车; 横行小车crane carrier 起重机载运车crane controller 起重控制器crane fall 起重机索crane motor / crane hoist type motor 起重机电动机crane platform 起重机平台crane rail 吊车轨，起重机轨道crane runner 吊车司机crane runway 起重机走道; 天车滑道crane weigher 吊车秤crane wheel 吊车车轮crane winch 起重机绞车lifting tackle 起重滑车lever of crane 起重机臂hoisting tools 起重工具吊具lifting rope 吊绳起重钢丝绳起重吊装术语：hoist / load up 起升lower / load down 下降hoist slowly / load up slowly 微微起升lower slowly / load down slowly 微微下降use main hoist/use main line 使用主钩use whip hoist/use whip line 使用小钩raise boom / boom up（臂架类吊车）抬起主臂lower boom / boom down （同上）降下主臂raise boom slowly / boom up slowly（臂架类吊车）微微抬起主臂lower boom slowly / boom down slowly （同上）微微降下主臂swing （根据指挥手势、旗语或）移动摆动stop 停止Emergency stop 紧急停止Extend boom / extend hydranlic boom （汽车吊类）伸长主臂Retract boom / shorten hydranlic boom （汽车吊类）缩回主臂raise the boom and lower the load /boom up and load down （汽车吊类）抬主臂降主钩（俗称顿杆松钩）lower the boom and raise the load /boom dwon and load up （汽车吊类）降主臂起主钩（俗称趴杆起钩）turn left 向左转turn right 向右转crane output / carrying capacity of crane / lifting capacity of crane 吊车起重能力crane load 起重机起重量; 起重机起重量crane rating 起重机定额; 起重机载重量crane radius 起重机起吊半径; 起重机伸臂活动半径; 起重机伸距craneage 吊车工时crane beam 行车梁起重机大梁crane stair 起重机楼梯hoist drive mechanism 起重机驱动机构travelling crab 起重机小车hoisting controller 起重控制器吊车控制手柄hoisting facility 起重设施lifting gear 起重装置crane (runway) girder 吊车梁crane support wall 吊车支承墙crane boom 起重机吊架; 起重架; 吊车臂; 吊车起重扒杆; 吊杆crane column 吊车柱crane hook / grab （or lift hook）（ or dolly）起重机吊钩crane jib 起重机吊杆crane bridge 起重机桥crane buffer 吊车缓冲器crane rope / crane cable起重钢绳; 起重机吊索; 吊车钢丝绳crane carriage 起重小车; 横行小车crane carrier 起重机载运车crane controller 起重控制器crane fall 起重机索crane motor / crane hoist type motor 起重机电动机crane platform 起重机平台crane rail 吊车轨，起重机轨道crane runner 吊车司机crane runway 起重机走道; 天车滑道crane weigher 吊车秤crane wheel 吊车车轮crane winch 起重机绞车lifting tackle 起重滑车lever of crane 起重机臂hoisting tools 起重工具吊具lifting rope 吊绳起重钢丝绳。

本科生毕业设计 (论文)外文翻译原文标题液压系统译文标题HYDRAULIC SYSTEMS作者所在系别作者所在专业作者所在班级作者姓名作者学号指导教师姓名指导教师职称完成时间2017 年 4 月15教务处制控制阀控制阀是操作者可访问的阀，用于引导系统内的流体流动以操作机器或其附件。

通过巧妙地使用控制阀，操作员可以调节液压缸的速度和运行。

注意：液压控制应平稳运行，以消除引起机器机械部件快速磨损和破坏的冲击运动。

执行机构（a）旋转叶片液压致动器，（b）线性液压致动器。

通过输入控制信号改变控制阀的位置，允许通过通道流动以操作致动器。

当致动器移动时，其运动沿反馈路径传递，从而抵消控制阀的原始运动。

因此，致动器的输出运动与输入控制运动成比例。

带反馈的旋转风门执行机构线性执行器（RAM）带反馈SPOOL阀门关闭和方向控制阀芯阀直接流到系统的各个部件，并可通过手柄，先导压力信号，电磁螺线管，电动马达和机械凸轮来操作。

用于滑动滑阀方向阀的典型应用是将流体控制到双作用液压缸，其在一个方向上移动时需要在活塞的一侧上的压力下的流体，而另一侧连接到排出管线。

在上述滑阀中，三位置阀芯通过反馈连杆保持在其位置。

在中央位置，所有部件都被锁定。

因此，显而易见的是，当阀芯保持中心时，气缸不能被轻便。

相对于各种端口移动阀芯的位置控制缺陷的方向，如果阀芯向左移动，高压油将通过阀门流到执行器的左侧。

同时，线性执行器的右侧将连接到排气口。

从而将线性致动器向右移动。

一旦致动器已经移动与控制运动成正比的一定量，线轴将自动地通过反馈链路移动到中心。

累积器描述液压蓄能器并解释其目的。

压力蓄能器用于需要储存压力能量以满足需求浪涌的液压系统中，它们还用于吸收液压冲击载荷，并在泵停止时保持压力时补偿小的内部泄漏。

最常见的蓄能器形式包括含有充气和加压柔性气囊的钢壳。

通过特殊阀将气囊预充到所需压力，然后密封以防止气体泄漏。

压力下的液压油进入蓄能器，压缩气囊，直到达到平衡。

外文原文：The Analysis of Cavitation Problems in the Axial Piston Pumpshu WangEaton Corporation,14615 Lone Oak Road,Eden Prairie, MN 55344This paper discusses and analyzes the control volume of a piston bore constrained by the valve plate in axial piston pumps. The vacuum within the piston bore caused by the rise volume needs to be compensated by the flow; otherwise, the low pressure may cause the cavitations and aerations. In the research, the valve plate geometry can be optimized by some analytical limitations to prevent the piston pressure below the vapor pressure. The limitations provide the design guide of the timings and overlap areas between valve plate ports and barrel kidneys to consider the cavitations and aerations. _DOI: 10.1115/1.4002058_Keywords: cavitation , optimization, valve plate, pressure undershoots1 IntroductionIn hydrostatic machines, cavitations mean that cavities or bubbles form in the hydraulic liquid at the low pressure and collapse at the high pressure region, which causes noise, vibration, and less efficiency.Cavitations are undesirable in the pump since the shock waves formed by collapsed may be strong enough to damage components. The hydraulic fluid will vaporize when its pressure becomes too low or when the temperature is too high. In practice, a number of approaches are mostly used to deal with the problems: (1) raise the liquid level in the tank, (2) pressurize the tank, (3) booster the inlet pressure of the pump, (4) lower the pumping fluid temperature, and (5) design deliberately the pump itself.Many research efforts have been made on cavitation phenomena in hydraulic machine designs. The cavitation is classified into two types in piston pumps: trapping phenomenon related one (which can be preventedby the proper design of the valve plate) and the one observed on the layers after the contraction or enlargement of flow passages (caused by rotating group designs) in Ref. (1). The relationship between the cavitation and the measured cylinder pressure is addressed in this study. Edge and Darling (2) reported an experimental study of the cylinder pressure within an axial piston pump. The inclusion of fluid momentum effects and cavitations within the cylinder bore are predicted at both high speed and high load conditions. Another study in Ref. (3) provides an overview of hydraulic fluid impacting on the inlet condition and cavitation potential. It indicates that physical properties (such as vapor pressure, viscosity, density, and bulk modulus) are vital to properly evaluate the effects on lubrication and cavitation. A homogeneous cavitation model based on the thermodynamic properties of the liquid and steam is used to understand the basic physical phenomena of mass flow reduction and wave motion influences in the hydraulic tools and injection systems (4). Dular et al. (5, 6) developed an expert system for monitoring and control of cavitations in hydraulic machines and investigated the possibility of cavitation erosion by using the computational fluid dynamics (CFD) tools. The erosion effects of cavitations have been measured and validated by a simple single hydrofoil configuration in a cavitation tunnel. It is assumed that the severe erosion is often due to the repeated collapse of the traveling vortex generated by a leading edge cavity in Ref. (7). Then, the cavitation erosion intensity may be scaled by a simple set of flow parameters: the upstream velocity, the Strouhal number, the cavity length, and the pressure. A new cavitation erosion device, called vortex cavitation generator, is introduced to comparatively study various erosion situations (8).More previous research has been concentrated on the valve plate designs, piston, and pump pressure dynamics that can be associated with cavitations in axial piston pumps. The control volume approach and instantaneous flows (leakage) are profoundly studied in Ref. [9]. Berta et al. [10] used the finite volume concept to develop a mathematical model in which the effects of port plate relief grooves have been modeled andthe gaseous cavitation is considered in a simplified manner. An improved model is proposed in Ref. [11] and validated by experimental results. The model may analyze the cylinder pressure and flow ripples influenced by port plate and relief groove design. Manring compared principal advantages of various valve plate slots (i.e., the slots with constant, linearly varying, and quadratic varying areas) in axial piston pumps [12]. Four different numerical models are focused on the characteristics of hydraulic fluid, and cavitations are taken into account in different ways to assist the reduction in flow oscillations [13].The experiences of piston pump developments show that the optimization of the cavitations/aerations shall include the following issues: occurring cavitation and air release, pump acoustics caused by the induced noises, maximal amplitudes of pressure fluctuations, rotational torque progression, etc. However, the aim of this study is to modify the valve plate design to prevent cavitation erosions caused by collapsing steam or air bubbles on the walls of axial pump components. In contrastto literature studies, the research focuses on the development of analytical relationship between the valve plate geometrics and cavitations. The optimization method is applied to analyze the pressure undershoots compared with the saturated vapor pressure within the piston bore.The appropriate design of instantaneous flow areas between the valveplate and barrel kidney can be decided consequently.2 The Axial Piston Pump and Valve PlateThe typical schematic of the design of the axis piston pump is shown in Fig. 1. The shaft offset e is designed in this case to generate stroking containment moments for reducing cost purposes.The variation between the pivot center of the slipper and swash rotating center is shown as a. The swash angle αis the variable that determines the amount of fluid pumped per shaft revolution. In Fig. 1, the n th piston-slipper assembly is located at the angle ofθ. The displacement of the n thnpiston-slipper assembly along the x-axis can be written asx n= R tan（α）sin（θ）+ a sec（α）+ e tan(α) (1)nwhere R is the pitch radius of the rotating group.Then, the instantaneous velocity of the n th piston isx˙n = R 2sec ()αsin （n θ）α+ R tan （α）cos （n θ）ω+ R 2sec ()αsin （α）α + e 2sec ()αα (2)where the shaft rotating speed of the pump is ω=d n θ / dt .The valve plate is the most significant device to constraint flow inpiston pumps. The geometry of intake/discharge ports on the valve plateand its instantaneous relative positions with respect to barrel kidneys areusually referred to the valve plate timing. The ports of the valve plateoverlap with each barrel kidneys to construct a flow area or passage,which confines the fluid dynamics of the pump. In Fig. 2, the timingangles of the discharge and intake ports on the valve plate are listed as(,)T i d δ and (,)B i d δ. The opening angle of the barrel kidney is referred to asϕ. In some designs, there exists a simultaneous overlap between thebarrel kidney and intake/discharge slots at the locations of the top deadcenter (TDC) or bottom dead center (BDC) on the valve plate on whichthe overlap area appears together referred to as “cross -porting” in thepump design engineering. The cross-porting communicates the dischargeand intake ports, which may usually lower the volumetric efficiency. Thetrapped-volume design is compared with the design of the cross-porting,and it can achieve better efficiency 14]. However, the cross-porting isFig. 1 The typical axis piston pumpcommonly used to benefit the noise issue and pump stability in practice.3 The Control Volume of a Piston BoreIn the piston pump, the fluid within one piston is embraced by the piston bore, cylinder barrel, slipper, valve plate, and swash plate shown in Fig. 3. There exist some types of slip flow by virtue of relativeFig. 2 Timing of the valve platemotions and clearances between thos e components. Within the control volume of each piston bore, the instantaneous mass is calculated asM= n V(3)nwhere ρ and n V are the instantaneous density and volumesuch that themass time rate of change can be given asFig. 3 The control volume of the piston boren n n dM dV d V dt dt dtρρ=+ (4) where d n V is the varying of the volume.Based on the conservation equation, the mass rate in the control volume isn n dM q dtρ= (5)where n q is the instantaneous flow rate in and out of one piston. From the definition of the bulk modulus,n dP d dt dtρρβ= (6) where Pn is the instantaneous pressure within the piston bore. Substituting Eqs. (5) and (6) into Eq. (4) yields(?)n n n n n ndP q dV d V w d βθθ=- (7) where the shaft speed of the pump is n d dtθω=. The instantaneous volume of one piston bore can be calculated by using Eq. (1) asn V = 0V + P A [R tan （α）sin （n θ）+ a sec （α） + e tan(α) ] (8)where P A is the piston sectional area and 0V is the volume of eachpiston, which has zero displacement along the x-axis (when n θ=0, π).The volume rate of change can be calculated at the certain swash angle, i.e., α =0, such thattan cos n p n ndV A R d αθθ=（）（） (9) in which it is noted that the piston bore volume increases or decreaseswith respect to the rotating angle of n θ.Substituting Eqs. (8) and (9) into Eq. (7) yields0[tan()cos()] [tan sin sec tan() ]n P n n n p n q A R dP d V A R a e βαθωθαθαα-=-++（）（）（）(10)4 Optimal DesignsTo find the extrema of pressure overshoots and undershoots in the control volume of piston bores, the optimization method can be used in Eq. (10). In a nonlinear function, reaching global maxima and minima is usually the goal of optimization. If the function is continuous on a closed interval, global maxima and minima exist. Furthermore, the global maximum (or minimum) either must be a local maximum (or minimum) in the interior of the domain or must lie on the boundary of the domain. So, the method of finding a global maximum (or minimum) is to detect all the local maxima (or minima) in the interior, evaluate the maxima (or minima) points on the boundary, and select the biggest (or smallest) one. Local maximum or local minimum can be searched by using the first derivative test that the potential extrema of a function f( · ), with derivative ()f ', can solve the equation at the critical points of ()f '=0 [15].The pressure of control volumes in the piston bore may be found as either a minimum or maximum value as dP/ dt=0. Thus, letting the left side of Eq. (10) be equal to zero yieldstan()cos()0n p n q A R ωαθ-= (11)In a piston bore, the quantity of n q offsets the volume varying and thendecreases the overshoots and undershoots of the piston pressure. In this study, the most interesting are undershoots of the pressure, which may fall below the vapor pressure or gas desorption pressure to cause cavitations. The term oftan()cos()p n A R ωαθ in Eq. (11) has the positive value in the range of intake ports (22ππθ-≤≤), shown in Fig. 2, which means that the piston volume arises. Therefore, the piston needs the sufficient flow in; otherwise, the pressure may drop.In the piston, the flow of n q may get through in a few scenariosshown in Fig. 3: (I) the clearance between the valve plate and cylinder barrel, (II) the clearance between the cylinder bore and piston, (III) the clearance between the piston and slipper, (IV) the clearance between the slipper and swash plate, and (V) the overlapping area between the barrel kidney and valve plate ports. As pumps operate stably, the flows in the as laminar flows, which can be calculated as [16]312IV k k Ln i I k h q p L ωμ==∑ (12)where k h is the height of the clearance, k L is the passage length,scenarios I –IV mostly have low Reynolds numbers and can be regarded k ω is the width of the clearance (note that in the scenario II, k ω =2π· r, in which r is the piston radius), and p is the pressure drop defined in the intake ports as p =c p -n p (13)where c p is the case pressure of the pump. The fluid films through theabove clearances were extensively investigated in previous research. The effects of the main related dimensions of pump and the operating conditions on the film are numerically clarified inRefs. [17,18]. The dynamic behavior of slipper pads and the clearance between the slipper and swash plate can be referred to Refs. [19,20]. Manring et al. [21,22] investigated the flow rate and load carrying capacity of the slipper bearing in theoretical and experimental methods under different deformation conditions. A simulation tool calledCASPAR is used to estimate the nonisothermal gap flow between the cylinder barrel and the valve plate by Huang and Ivantysynova [23]. The simulation program also considers the surface deformations to predict gap heights, frictions, etc., between the piston and barrel andbetween the swash plate and slipper. All these clearance geometrics in Eq.(12) are nonlinear and operation based, which is a complicated issue. In this study, the experimental measurements of the gap flows are preferred. If it is not possible, the worst cases of the geometrics or tolerances with empirical adjustments may be used to consider the cavitation issue, i.e., minimum gap flows.For scenario V, the flow is mostly in high velocity and can be described by using the turbulent orifice equation as((Tn d i d d q c A c A θθ= (14)where Pi and Pd are the intake and discharge pressure of the pump and ()i A θ and ()d A θ are the instantaneous overlap area between barrel kidneys and inlet/discharge ports of the valve plate individually.The areas are nonlinear functions of the rotating angle, which is defined by the geometrics of the barrel kidney, valve plate ports,silencing grooves, decompression holes, and so forth. Combining Eqs.(11) –(14), the area can be obtained as3()K IV A θ==(15)where ()A θ is the total overlap area of ()A θ=()()i d A A θλθ+, and λ is defined as=In the piston bore, the pressure varies from low tohigh while passing over the intake and discharge ports of the valve plates. It is possible that the instantaneous pressure achieves extremely low values during the intake area( 22ππθ-≤≤ shown in Fig. 2) that may be located below the vapor pressure vp p , i.e., n vp p p ≤;then cavitations canhappen. To prevent the phenomena, the total overlap area of ()A θ mightbe designed to be satisfied with30()K IV A θ=≥(16)where 0()A θ is the minimum area of 0()A θ=0()()i d A A θλθ+ and 0λis a constant that is0λ=gaseous form. The vapor pressure of any substance increases nonlinearly with temperature according to the Clausius –Clapeyron relation. With the incremental increase in temperature, the vapor pressure becomes sufficient to overcome particle attraction and make the liquid form bubbles inside the substance. For pure components, the vapor pressure can be determined by the temperature using the Antoine equation as /()10A B C T --, where T is the temperature, and A, B, and C are constants[24].As a piston traverse the intake port, the pressure varies dependent on the cosine function in Eq. (10). It is noted that there are some typical positions of the piston with respect to the intake port, the beginning and ending of overlap, i.e., TDC and BDC (/2,/2θππ=- ) and the zero displacement position (θ =0). The two situations will be discussed as follows:(1) When /2,/2θππ=-, it is not always necessary to maintain the overlap area of 0()A θ because slip flows may provide filling up for the vacuum. From Eq. (16), letting 0()A θ=0,the timing angles at the TDC and BDC may be designed as31cos ()tan()122IV c vpk k i I P k p p h A r L ωϕδωαμ--≤+∑ (17) in which the open angle of the barrel kidney is . There is nocross-porting flow with the timing in the intake port.(2) When θ =0, the function of cos θ has the maximum value, which can provide another limitation of the overlap area to prevent the low pressure undershoots suchthat 30(0)K IVA =≥ (18)where 0(0)A is the minimum overlap area of 0(0)(0)i A A =.To prevent the low piston pressure building bubbles, the vaporpressure is considered as the lower limitation for the pressure settings in Eq. (16). The overall of overlap areas then can be derived to have adesign limitation. The limitation is determined by the leakage conditions, vapor pressure, rotating speed, etc. It indicates that the higher the pumping speed, the more severe cavitation may happen, and then the designs need more overlap area to let flow in the piston bore. On the other side, the low vapor pressure of the hydraulic fluid is preferred to reduce the opportunities to reach the cavitation conditions. As a result, only the vapor pressure of the pure fluid is considered in Eqs. (16)–(18). In fact, air release starts in the higher pressure than the pure cavitation process mainly in turbulent shear layers, which occur in scenario V.Therefore, the vapor pressure might be adjusted to design the overlap area by Eq. (16) if there exists substantial trapped and dissolved air in the fluid.The laminar leakages through the clearances aforementioned are a tradeoff in the design. It is demonstrated that the more leakage from the pump case to piston may relieve cavitation problems.However, the more leakage may degrade the pump efficiency in the discharge ports. In some design cases, the maximum timing angles can be determined by Eq. (17)to not have both simultaneous overlapping and highly low pressure at the TDC and BDC.While the piston rotates to have the zero displacement, the minimum overlap area can be determined by Eq. 18 , which may assist the piston not to have the large pressure undershoots during flow intake.6 ConclusionsThe valve plate design is a critical issue in addressing the cavitation or aeration phenomena in the piston pump. This study uses the control volume method to analyze the flow, pressure, and leakages within one piston bore related to the valve plate timings. If the overlap area developed by barrel kidneys and valve plate ports is not properly designed, no sufficient flow replenishes the rise volume by the rotating movement. Therefore, the piston pressure may drop below the saturated vapor pressure of the liquid and air ingress to form the vapor bubbles. To control the damaging cavitations, the optimization approach is used to detect the lowest pressure constricted by valve plate timings. The analytical limitation of the overlap area needs to be satisfied to remain the pressure to not have large undershoots so that the system can be largely enhanced on cavitation/aeration issues.In this study, the dynamics of the piston control volume is developed by using several assumptions such as constant discharge coefficients and laminar leakages. The discharge coefficient is practically nonlinear based on the geometrics, flow number, etc. Leakage clearances of the control volume may not keep the constant height and width as well in practice due to vibrations and dynamical ripples. All these issues are complicated and very empirical and need further consideration in the future. Theresults presented in this paper can be more accurate in estimating the cavitations with these extensive studies.Nomenclature0(),()A A θθ= the total overlap area between valve plate ports and barrel kidneys 2()mmAp = piston section area 2()mmA, B, C= constantsA= offset between the piston-slipper joint and surface of the swash plate 2()mmd C = orifice discharge coefficiente= offset between the swash plate pivot and the shaft centerline of the pump 2()mmk h = the height of the clearance 2()mmk L = the passage length of the clearance 2()mmM= mass of the fluid within a single piston (kg)N= number of pistonsn = piston and slipper counter,p p = fluid pressure and pressure drop (bar)Pc= the case pressure of the pump (bar)Pd= pump discharge pressure (bar)Pi = pump intake pressure (bar)Pn = fluid pressure within the nth piston bore (bar)Pvp = the vapor pressure of the hydraulic fluid(bar)qn, qLn, qTn = the instantaneous flow rate of each piston(l/min)R = piston pitch radius 2()mmr = piston radius (mm)t =time (s)V = volume 3()mmwk = the width of the clearance (mm)x ,x ˙= piston displacement and velocity along the shaft axis (m, m/s) x y z --=Cartesian coordinates with an origin on the shaft centerline x y z '''--= Cartesian coordinates with an origin on swash plate pivot ,αα=swash plate angle and velocity (rad, rad/s)β= fluid bulk modulus (bar)δδ= timing angle of valve plates at the BDC and TDC (rad),B Tϕ= the open angle of the barrel kidney(rad)ρ= fluid density(kg/m3),θω= angular position and velocity of the rotating kit (rad, rad/s)μ=absolute viscosity(Cp),λλ= coefficients related to the pressure drop外文中文翻译：在轴向柱塞泵气蚀问题的分析本论文讨论和分析了一个柱塞孔与配流盘限制在轴向柱塞泵的控制量设计。

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中英文对照起重机术语大全起重机（crane）moblie crane 移动式起重机truck crane 汽车式起重机wheel crane / wheeled crane 轮胎起重机crawler crane / caterpillar crane 履带吊；履带式起重机tower crane 塔吊；塔式起重机-construction tower cranes / building tower crane 建筑塔式起重机，建筑塔机-luffing jib tower crane 动臂塔式起重机—tower jib crane 塔式挺杆起重机(含义与上同）bridge crane/traveling crane/overhead crane 桥吊；桥式吊车; 桥式起重机—electric traveling crane 电动桥式起重机（俗称行车、天车）—electric double—beam bridge crane 电动双梁桥式起重机portal crane / portal bridge crane门式起重机- semi—goliath crane 半门式起重机- semi—portal bridge crane 半龙门起重机gantry cranes 龙门起重机- rubber tyred gantry crane 轮胎式龙门吊- electric gantry crane 电动龙门式起重机— hook gantry crane 吊钩龙门吊— economical gantry crane 简单龙门起重机；简易龙门起重机— rubber tyred container gantry crane 轮胎式集装箱龙门起重机barges / floating Cranes 船式起重机; 浮吊；浮式起重机水上起重机boom crane 吊杆起重机; 桁梁起重机；臂式起重机; 伸臂起重机bucket crane 料罐起重机；吊斗起重机building crane 建筑起重机cable crane 索道起重机；缆索起重机container crane 集装箱起重机electric crane 电动吊车; 电动起重机；电力起重机electriomagnet crane 电磁铁起重机electric jib crane 电动单臂起重机fixed crane 固定式起重机climbing crane 爬升式起重机；攀爬式起重机fixed derrick crane 固定式动臂起重机fixed jib crane 固定式悬臂起重机flying crane helicopter 起重直升机hoist crane 起重葫芦hoisting crane 升降起重机hook type crane 钩式起重机twin hood crane 双钩吊车mobile crane 移动式吊车; 移动式起重机quay crane 码头起重机; 码头桥式起重机; 港岸起重机revolving track crane 回转式轨道起重机circular crane 旋转式吊车环形吊车roof crane 屋顶起重机transporter crane 桁架式起重机electric crane 电动吊车; 电动起重机gasoline crane 汽油起重机hydraulic crane 液力起重机；液压起重机derrick crane 人字扒杆人字起重机—travelling derrick crane 移动式人字扒杆jib crane / cantilever crane 悬臂式起重机wall crane 壁式起重机heavy duty crane 重型起重机crane output / carrying capacity of crane / lifting capacity of crane 吊车起重能力crane load 起重机起重量；起重机起重量crane rating 起重机定额; 起重机载重量crane radius 起重机起吊半径；起重机伸臂活动半径; 起重机伸距craneage 吊车工时crane beam 行车梁起重机大梁crane stair 起重机楼梯hoist drive mechanism 起重机驱动机构travelling crab 起重机小车hoisting controller 起重控制器吊车控制手柄hoisting facility 起重设施lifting gear 起重装置crane (runway) girder 吊车梁crane support wall 吊车支承墙crane boom 起重机吊架；起重架; 吊车臂; 吊车起重扒杆；吊杆crane column 吊车柱crane hook / grab （or lift hook)（or dolly）起重机吊钩crane jib 起重机吊杆crane bridge 起重机桥crane buffer 吊车缓冲器crane rope / crane cable起重钢绳; 起重机吊索; 吊车钢丝绳crane carriage 起重小车; 横行小车crane carrier 起重机载运车crane controller 起重控制器crane fall 起重机索crane motor / crane hoist type motor 起重机电动机crane platform 起重机平台crane rail 吊车轨，起重机轨道crane runner 吊车司机crane runway 起重机走道; 天车滑道crane weigher 吊车秤crane wheel 吊车车轮crane winch 起重机绞车lifting tackle 起重滑车lever of crane 起重机臂hoisting tools 起重工具吊具lifting rope 吊绳起重钢丝绳起重吊装术语：hoist / load up 起升lower / load down 下降hoist slowly / load up slowly 微微起升lower slowly / load down slowly 微微下降use main hoist/use main line 使用主钩use whip hoist/use whip line 使用小钩raise boom / boom up（臂架类吊车）抬起主臂lower boom / boom down （同上）降下主臂raise boom slowly / boom up slowly（臂架类吊车）微微抬起主臂lower boom slowly / boom down slowly （同上）微微降下主臂swing （根据指挥手势、旗语或）移动摆动stop 停止Emergency stop 紧急停止Extend boom / extend hydranlic boom （汽车吊类）伸长主臂Retract boom / shorten hydranlic boom (汽车吊类）缩回主臂raise the boom and lower the load /boom up and load down （汽车吊类)抬主臂降主钩（俗称顿杆松钩）lower the boom and raise the load /boom dwon and load up （汽车吊类）降主臂起主钩(俗称趴杆起钩）turn left 向左转turn right 向右转crane output / carrying capacity of crane / lifting capacity of crane 吊车起重能力crane load 起重机起重量；起重机起重量crane rating 起重机定额; 起重机载重量crane radius 起重机起吊半径; 起重机伸臂活动半径；起重机伸距craneage 吊车工时crane beam 行车梁起重机大梁crane stair 起重机楼梯hoist drive mechanism 起重机驱动机构travelling crab 起重机小车hoisting controller 起重控制器吊车控制手柄hoisting facility 起重设施lifting gear 起重装置crane (runway) girder 吊车梁crane support wall 吊车支承墙crane boom 起重机吊架; 起重架; 吊车臂；吊车起重扒杆; 吊杆crane column 吊车柱crane hook / grab （or lift hook）（or dolly)起重机吊钩crane jib 起重机吊杆crane bridge 起重机桥crane buffer 吊车缓冲器crane rope / crane cable起重钢绳；起重机吊索; 吊车钢丝绳crane carriage 起重小车；横行小车crane carrier 起重机载运车crane controller 起重控制器crane fall 起重机索crane motor / crane hoist type motor 起重机电动机crane platform 起重机平台crane rail 吊车轨，起重机轨道crane runner 吊车司机crane runway 起重机走道; 天车滑道crane weigher 吊车秤crane wheel 吊车车轮crane winch 起重机绞车lifting tackle 起重滑车lever of crane 起重机臂hoisting tools 起重工具吊具lifting rope 吊绳起重钢丝绳。

1.1起重机简介起重机是一种用来起重与空中搬运重物的机械设备，广泛应用于工矿企业、车站、港口、仓库、建筑工地等部门。

它对减轻工人劳动强度、提高劳动生产率、促进生产过程机械化起着重要作用，是现代化生产中不可缺少的工具。

起重机包括桥式、门式、梁氏和旋转式等多种，其中以桥式起重机的应用最广。

桥式类起重机又分为通用桥式起重机、冶金专用起重机、龙门起重机与缆索起重机等。

桥式起重机是桥架在高架轨道上运行的一种桥架型起重机，又称天车。

桥式起重机的桥架沿铺设在两侧高架上的轨道纵向运行，起重小车沿铺设在桥架上的轨道横向运行，构成一矩形的工作范围，就可以充分利用桥架下面的空间吊运物料，不受地面设备的阻碍。

1.1.1普通桥式起重机组成部分（1）桥架（又称大车）桥架是起重机的基本构件，由主梁、端梁、走台等部分组成。

（2）大车移动机构大车移动机构由大车拖动电动机、联轴节、减速器、制动器及车轮等部分。

整个桥式起重机在大车移动机构拖动下沿车间长度方向的导轨移动。

（3）小车小车安放在桥架导轨上，可沿车间宽度方向移动。

小车移动机构由小车电动机、制动器、联轴节、减速器、车轮等部分组成。

（4）提升机构提升机构由提升电动机、提升减速器、制动器、卷筒、静滑轮、吊钩等部分组成。

提升电动机经联轴节、制动轮与减速器联接，钢丝绳另一端装有吊钩。

当卷筒转动时，吊钩就随钢丝绳在卷筒上缠绕而上升或下降，对于起重量在15t以上的提升机构，一般配备两套吊钩上随着卷筒而获得上下运动，随着小车在宽度方向获得左右运动，随着大车沿车间长度方向作前后运动，所以就实现了重物在垂直、纵向、横向三个方向的运动，将重物移动到车向的任一位置。

（5）驾驶室驾驶室是操纵起重机的吊舱，驾驶室一般固定在主梁一端的下面，也有少数装在小车下方随小车移动，驾驶室内有小车、大车、提升机构的控制装置及保护装置。

1.1.2桥式起重机的工作原理起重机由大车电动机驱动沿车间两边的轨道作纵向前后运动；小车及提升机构由小车电动机驱动沿桥架上的轨道作横向左右运动；在升降重物时由起重电动机驱动作垂直上下运动，实现重物在垂直、横向、纵向三个方向的运动。

液压系统知识一个完整的液压系统由五个部分组成，即动力元件、执行元件、控制元件、辅助无件和液压油。

动力元件的作用是将原动机的机械能转换成液体的压力能，指液压系统中的油泵，它向整个液压系统提供动力。

液压泵的结构形式一般有齿轮泵、叶片泵和柱塞泵。

执行元件(如液压缸和液压马达)的作用是将液体的压力能转换为机械能，驱动负载作直线往复运动或回转运动。

控制元件(即各种液压阀)在液压系统中控制和调节液体的压力、流量和方向。

根据控制功能的不同，液压阀可分为压力控制阀、流量控制阀和方向控制阀。

压力控制阀又分为溢流阀(安全阀)、减压阀、顺序阀、压力继电器等；流量控制阀包括节流阀、调整阀、分流集流阀等；方向控制阀包括单向阀、液控单向阀、梭阀、换向阀等。

根据控制方式不同，液压阀可分为开关式控制阀、定值控制阀和比例控制阀。

辅助元件包括油箱、滤油器、油管及管接头、密封圈、压力表、油位油温计等。

液压油是液压系统中传递能量的工作介质，有各种矿物油、乳化液和合成型液压油等几大类。

液压的原理它是由两个大小不同的液缸组成的，在液缸里充满水或油。

充水的叫“水压机”；充油的称“油压机”。

两个液缸里各有一个可以滑动的活塞，如果在小活塞上加一定值的压力，根据帕斯卡定律，小活塞将这一压力通过液体的压强传递给大活塞，将大活塞顶上去。

设小活塞的横截面积是S1，加在小活塞上的向下的压力是F1。

于是，小活塞对液体的压强为P=F1/SI, 能够大小不变地被液体向各个方向传递”。

大活塞所受到的压强必然也等于P。

若大活塞的横截面积是S2，压强P在大活塞上所产生的向上的压力F2=PxS2 ，截面积是小活塞横截面积的倍数。

从上式知，在小活塞上加一较小的力，则在大活塞上会得到很大的力，为此用液压机来压制胶合板、榨油、提取重物、锻压钢材等。

液压传动的发展史液压传动和气压传动称为流体传动，是根据17世纪帕斯卡提出的液体静压力传动原理而发展起来的一门新兴技术，1795年英国约瑟夫•布拉曼(Joseph Braman,1749-1814)，在伦敦用水作为工作介质,以水压机的形式将其应用于工业上,诞生了世界上第一台水压机。