车辆与动力工程外文翻译外文文献英文翻译自动变速器
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毕业设计外文翻译THE RESEARCHS OFAMT SHIFTING SCHEDULESThe modern automatic transmission is by far,the most complicated mechanical component in today`s automobile.It is a type of transmission that sifts itself.A fluid coupling or torque converter is used instead of a manually operated clutch to connect the transmission to the engine.There are two basic types of automatic transmission based on whether the vehicle is rear wheel drive or front wheel drive.On a rear wheel drive car,the transmission is usually mounted to the back of the engine and is located under the hump in the center of the floorboard alongside the gas pedal position.A drive shaft connects the transmission to the final drive which is located in the rear axle and is used to send power to the rear wheels.Power flow on this system is simple and straight forward going from the engine,through the torque converter,then trough the transmission and drive shaft until it reaches the final drive where it is split and sent to the two rear transmission.On a front wheel drive car,the transmission is usually combined with the final drive to form what is called a transaxle.The engine on a front wheel drive car is usually mounted sideways in the car with the transaxle tucked under it on the side of the engine facing the rear of the car.Frontaxles are connected directly to the transaxle and provide power to front wheels.In this example,power floes from the engine,through the torque converter to a larger chain that sends the power through a 180 degree turn to the transmission that is along side the engine.From there,the power is routed through the transmission to the final drive where it is split and sent to the two front wheels through the drive axles.There are a number of other arrangements including front drive vehicles where the engine is mounted front to back instead of sideways and there are other systems that drive all four wheels but the two systems described here are by far the most popular.A much less popular rear and is connected by a drive shaft to the torque converter which is still mounted on the engine.This system is found on the new Corvette and is used in order to balance the weight evenly between the front and rear wheels for improved performance and handling.Another rear drive system mounts everything,the engine,transmission and final drive in the rear.This rear engine arrangement is popular on the Porsche。
外文翻译Auto TransmissionFirst, an overview of automotive transmission and the development trendAutomobile available more than a century, especially from the mass production of motor vehicles and the automotive industry since the development of large, Car has been the economic development of the world for mankind to enter the modern life and have had a tremendous impact on the immeasurable, The progress of human society has made indelible contributions to the great, epoch-making set off arevolution. From From the vehicle as a power plant using internal combustion engine to start, auto transmission has become an important component. Is Generation is widely used in automotive reciprocating piston internal combustion engine with a small size, light weight, reliable operation and the use of The advantages of convenience, but its torque and speed range of smaller changes, and complex condition requires the use of motor vehicles Traction and the speed can be considerable changes in the scope. Therefore, its performance and vehicle dynamics and economy of There are large inter-contradictions, which contradictions of modern automotive internal combustion engine by itself is insoluble. Because Here, in the automotive power train set up the transmission and main reducer in order to achieve the purpose of deceleration by moment. Speed The main function of performance: ⑴ change gear ratio of motor vehicles, and expand the wheel drive torque and rotational speed of the Fan Wai, in order to adapt to constantly changing driving cycle, while the engine in the most favorable conditions within the scope of work; ⑵no change in the direction of engine rotation, under the premise of the realization of cars driving back; ⑶the realization of the free, temporary Interruption of power transmission, in order to be able to start the engine, idling, etc.. V ariable-speed drive transmission by the manipulation of institutions and agencies. Change the transmission ratio by way of transmission is divided into There are class-type, non-stage and multi-purpose three. Have class most widely used transmission. It uses gear drive, with a number of transmission ratio setting. Stepless transmission Continuously V ariable Transmission (CVT) transmission ratio of a certain The framework of multi-level changes may be unlimited, there is a common type of power and torque (dynamic fluid-type) and so on. Continuously V ariable Transmission Transmission development is the ultimate goal, because only it can make the most economical engine in working condition Can provide the best vehicle fuel economy and optimal power in order to provide the most comfortable By the feeling. Today's CVT is a typical representative of the CVTand IVT, however as a result of the reliability of Poor, non-durable materials and high cost issues, development is not very good. Comprehensive refers to transmission torque converter and the mechanical components have the level of transmission variable hydraulic mechanical Speed, the transmission ratio can be between the maximum and minimum range of a few discontinuous change for no class, but its Significantly lower transmission efficiency than the efficiency of gear drives. 2 By manipulation, transmission control type can be divided into mandatory, automatic and semi-automatic control to manipulate three - Species . Mandatory on the driver to manipulate the direct transmission gear shift control for the majority of motor vehicles used Also known as Manual Transmission Manual Transmission (MT). Automatic transmission control selection of the transmission ratio (transmission) is carried out automatically. Just add the driver to manipulate Speed pedal, you can control the speed, also known as Automatic Transmission Automatic Transmission (A T). It is According to the speed and load (throttle pedal travel) for two-parameter control, stall in accordance with the above two Parameters to automatically take-off and landing.A T and MT in common is that they are level transmission, but A T According to the speed of the speed shift automatically, you can eliminate the manual transmission "setback" of the shift feel. However, A T also have many drawbacks, such as body complex, mechanical efficiency is not high, high cost, reliability and control Sensitivity remains to be increasing . AMT (Automated Mechanical Transmission) is in the traditional dry clutch and manual transmission gear based on the transformation of form, mainly to change the part of the manual gearshift control. That is, the overall structure of the MT cases the same switch to electronically controlled automatic transmission to achieve. Semi-automatic control, there are two forms of transmission. A number of stalls is a common automatic control, and the remaining stalls manipulated by the driver; the other is pre-style, that is, pre-selected pilot stalls, the clutch pedal in the down or release the accelerator pedal, the for retirement or an electromagnetic device to shift the hydraulic device. In recent years, with advances in vehicle technology and road traffic density increased, the performance requirements of the transmission is also getting higher and higher. A large number of automotive engineers in improving the performance of automobile transmission study a great deal of effort devoted to the rapid transmission of technology development, such as A T, AMT, DCT, CVT and the emergence of IVT.2003 Hyundai A T, AMT, DCT, CVT forum reached a consensus on the following:in the next Development, MT will continue to be the most widely used automotive transmission, AMT will increase the proportion of the application, A T also Will occupy a large market share, CVT's use of certain limitations, can only be due to a number of small displacement Car, DCT (dual clutch transmission) will also be the budding growth. From 2003 to now, vehicle speed Thedevelopment of devices and the forum basically the consensus reached by consensus. By comparing the analysis, the traditional mechanical transmission is still the most widely used vehicle change Speed. Although it has many shortcomings, such as shifting the impact of large, bulky, cumbersome to manipulate and so on; however, it also There are many advantages, such as high transmission efficiency, reliable operation, long life, manufacturing processes mature and low cost. Therefore, if we can improve the mechanical transmission of the above-mentioned shortcomings, it still has great room for development.Second, Manual Transmission Fault DiagnosisManual transmission at the beginning of the fault diagnosis prior toFailure to confirm from other parts is not: to check the tire And wheels, to confirm the normal tire pressure, and the wheel is flat V alue of; to confirm instead of noise and vibration from the engine. Clutch , And steering and suspension, etc..(A), skip file1. PhenomenonV ehicle acceleration, deceleration, climbing or severe vehicle vibration, the gear lever neutral position automatically jump.2. Reasons① self-locking device of the ball did not enter the grooves or linked file does not meet the full-gear tooth meshing long;② self-locking device worn groove ball or serious, self-locking spring is too soft or broken fatigue;③ gear along the direction of tooth wear as a long cone-shaped;④ one or two too松旷shaft bearing, so that one or two three-axis and the crankshaft axis of the heart or different transmission and clutch shell shell bonding plane of the vertical axis the relative change in the crankshaft;⑤ Second Gear axis often axial or radial gap is too large;⑥ the axis of axial or radial gap is too large.3. Fault diagnosis and troubleshootingJump to file stalls Unascertained: After taking heat the entire vehicle, increase the use of continuous, slow approach to road test each file is determined.Will jump to the gear lever hanging file stalls the engine off, transmission cover removed carefully to observe the mating dance gear case file.① engagement does not meet the length, then the resulting fault;② to reach a total length of engagement, should continue to check;③ check mating wear parts: wear into a cone, then failure may be caused by;④ check b-axis of the gear profile and the axis of the axial and radial clearance, clearance is too large, then failure may be caused by;⑤ check self-locking devices, locking devices, if only a very small dynamic resistance, and even feel the ball is not plugged groove (the transmission cover caught in the vice, the hand-shaking shift stroke), the fault for the bad performance of self-locking ; Otherwise, the fault for the clutch and gearbox shell bonding plane and the vertical axis of the crankshaft caused by changes.(B), arbitrary files1. PhenomenonTechnical condition in the clutch normal circumstances, transmission at the same time put up or two files linked to the need to stall, the results linked to other stalls.2. Reasons① interlocking device failure: if the fork shaft, pin or interlocking interlocking ball too much wear and tear, etc.;② the bottom of the arc gear face wear and tear is too large or fork axis of the allocated blocks wear groove is too large;③ball pin gear lever broken or the ball-hole, ball松旷wear too. In short arbitrary file transmission is mainly due to institutional failure manipulation.3. Fault diagnosis and troubleshooting① linked to the need to stall, the results linked to the other stalls: rocking gear lever, to check their point of view before, if in excess of the normal range, while the lower end of failure by the gear lever ball pin and the positioning groove ball with or松旷, the ball is too large holes caused by wear and tear. Swung shift 360 °, compared with a broken pin.② If the pendulum angle to normal, still not on, or linked to more than picking file, then the lower end of failure by the gear lever away from the limitations arising from the groove in (due to break away from the bottom of the arc-shaped guide groove face wear and tear or wear).③ At the same time linked to the two files: the fault caused by the interlocking device failure.(C), the difficulties linked to files1. PhenomenonClutch technical condition, but can not be linked smoothly linked file into the stalls, often percussive sound gear.2. Reasons① synchronizer failure;② Bending fork shaft, locking the spring strong, ball injury, etc.;③ a shaft or a spline shaft bending injury;④ inadequate or excessive gear oil, gear oil does not meet the specifications.3. Fault diagnosis and troubleshooting①Synchronizer check whether the fall to pieces, cone ring is conical spiral groove wear, whether worn slider, spring is too soft, such as elastic.② If the Synchronizer normal, check whether the bending of a shaft, spline wear is severe.③ check whether the mobile axis normal fork.(D), abnormal sound transmission1. PhenomenonTransmission refers to transmission work abnormal sound when the sound is not normal.2. Reasons1) abnormal sound gearGear wear off very thin gap is too large, the impact of running in; bad tooth meshing, such as the repair did not replace the gear pairs. New and old gear with the gear mesh can not be correct; tooth metal fatigue spalling or damage to individual teeth broken; gear and the spline shaft with松旷, or the axial gear clearance is too large; axis caused by bending or bearing松旷space to change gears.2) Bearing ringSerious bearing wear; Bearing (outer) ring with the journal blocks (holes) with the loose; Ball Bearing Ma break-up or a point of ablation.3) ring made for other reasonsSuch as the transmission within缺油, lubricants have been thin, too thick or quality deterioration; transmission into the foreign body inside; some loose bolts fastening; odometer or the odometer shaft ring gear, such as fat.3. Troubleshooting①transmission issued metal dry friction sound, which is缺油and the poor quality of oil. Refueling and inspection should be the quality of oil, if necessary, replacement.② for moving into a file if the sound obvious, namely, the profile of gear tooth wear; If the occurrence of cyclical noise, while damage to individual teeth.③when the ring gap, and riding the clutch pedal under the noise disappeared after the general axis is a before and after the bearing or regular engagement ring gear; if any files are changed into the ring, after more than two-axis bearing ring.④transmission occurs when a sudden impact the work of sound, most of the tooth was broken and should be removed timely transmission inspection cover to prevent mechanicaldamage.⑤moving, only for transmission of a file into the ring gear made in the above-mentioned good premise, it should check with improper gear mesh, if necessary, should be re-assembling a pair of new gear. In addition, it may be synchronizer gear wear or damage should be repaired or replaced depending on the circumstances.⑥ when shifting gear ring made of impact, it may be the clutch or the clutch pedal can not be separated from stroke is incorrect, damaged synchronizer, excessive idling, gear improperly adjusted or tight-oriented, such as Bush. In such cases, to check whether the separation of the clutch, and then adjust the idle speed or the gear lever, respectively, the location, inspection-oriented with the bearing bushing and separation tightness.If excluded from the above examinations, the transmission is still made ring, should check the shaft bearings and shaft hole with the situation, bearing the state of their own technology, etc.; as well, and then view the odometer shaft and ring gear is made and, if necessary, be repaired or replacement.(E), transmission oil1. PhenomenonAround the transmission gear lubricants, transmission gear box to reduce the fuel can be judged as lubricant leakage.2. Reasons and troubleshooting① improper oil selection, resulting in excessive foam, or the volume too much oil, when in need of replacement or adjust the lubricant oil;② side cover is too loose, damaged gaskets, oil seal damage, damage to seals and oil seals should be replaced with new items;③ release and transmission oil tank and side cover fixed bolts loosening, tightening torque should be required;④ broken gear-housing shell or extended wear and tear caused by oil spills, must be replaced;⑤ odometer broken loose gear limit device must be locked or replaced; gear oil seal oil seal oil should be replaced.Third, the maintenance manual gearboxSantana is now as an example:Santana used to manually synchronize the entire, multi-stage gear transmission, there are four forward one block and reverse gear. Block are forward-lock synchronizer ring inertial, body-wide shift synchronizer nested engagement with a reasonable structure, the layout of a compact, reliable, long life and so on. However, if the use and maintenance is not the right way to do so, failure mayoccur at any time.The proper use of Synchronizer:1, the use of addition and subtraction block off both feet. Block addition and subtraction, if the clutch with one foot, then the speed at the time of addition and subtraction block must be correct, the timing should be appropriate and, if necessary, to addition and subtraction can be blocked off both feet, so that addition and subtraction method can reduce the block with Gear speed difference between the circumference, thereby reducing wear and tear Synchronizer to extend the life of Synchronizer.2, prohibited the use of tap-shift gear lever when the method (that is, a push of the operation of a song). Hand should always hold down the shift, this can greatly reduce the synchronizer sliding lock Moreton Central time and reduce wear and tear.3, no state in the gap off the use of force挂挡synchronizer start the engine. Moment of inertia as a great engine, the friction torque Synchronizer also small, so the time synchronization process is very long, so that lock ring temperature increased sharply, it is easy to burn synchronizer.4, is strictly prohibited by synchronizer clutch instead of the initial (that is, the use of non-use of the clutch friction synchronizer start挂挡role), control speed and braking.The correct use of lubricants:Santana at the factory, the transmission has been added to the quality of lubricating oil, under normal circumstances, the level of the transmission lubrication need to be checked. However, when normal travel 100,000 kilometers 10,000 kilometers -20 after the first lubricating oil must be replaced. Santana grade lubricants used in transmission as follows: Gear Oil API-GLA (MIL-L2105), SAE80 or SAE80W-90 grade汽车变速器一、汽车变速器概述及发展趋势汽车问世百余年来,特别是从汽车的大批量生产及汽车工业的大发展以来,汽车己为世界经济的发展、为人类进入现代生活,产生了无法估量的巨大影响,为人类社会的进步作出了不可磨灭的巨大贡献,掀起了一场划时代的革命。
毕业设计欧阳歌谷(2021.02.01)外文翻译THE RESEARCHS OFAMT SHIFTING SCHEDULESThe modern automatic transmission is by far,the most complicated mechanical component in today`s automobile.It is a type of transmission that sifts itself.A fluid coupling or torque converter is used instead of a manually operated clutch to connect the transmission to the engine.There are two basic types of automatic transmission based on whether the vehicle is rear wheel drive or front wheel drive.On a rear wheel drive car,the transmission is usually mounted to the back of the engine and is located under the hump in the center of the floorboard alongside the gas pedal position.A drive shaft connects the transmission to the final drive which is located in the rear axle and is used to send power to the rear wheels.Power flow on this system is simple and straight forward going from the engine,through the torque converter,then trough the transmission and drive shaft until it reaches the final drive where it is split and sent to the two rear transmission.On a front wheel drive car,the transmission is usually combined with the final drive to form what is called a transaxle.The engine on a front wheel drive car is usually mounted sideways in the car with the transaxle tucked under it on the side of the engine facing the rear of the car.Front axles are connected directly to the transaxle and provide power to front wheels.In this example,power floes from the engine,through the torque converter to a larger chain that sends the power through a 180 degree turn to the transmission that is along side the engine.From there,the power is routed through the transmission to the final drive where it is split and sent to the two front wheels throughthe drive axles.There are a number of other arrangements including front drive vehicles where the engine is mounted front to back instead of sideways and there are other systems that drive all four wheels but the two systems described here are by far the most popular.A much less popular rear and is connected by a drive shaft to the torque converter which is still mounted on the engine.This system is found on the new Corvette and is used in order to balance the weight evenly between the front and rear wheels for improved performance and handling.Another rear drive system mounts everything,the engine,transmission and final drive in the rear.This rear engine arrangement is popular on the Porsche。
Current situation and development trend of automatic transmissionFirst, transmission profile1 manual transmission (MT)As we all know, the manual transmission gearbox is one of the most common car, its basic principle is to perform power transmission with a few parallel shafts and several meshing spur or helical gear, namely the input shaft axis and the axis constitute the main gearbox, plus a reverse gear and shaft synchronizer etc.. The working process is as follows: the driver through the drive rod to achieve different gear meshing, and ultimately to achieve different gear ratio gear.2 automatic manual transmission (AMT)Automatic manual transmission (AMT) is actually a machine system to complete the operation of the clutch and select the two movements. The AMT driver is simple, saves the clutch pedal, as long as the driver stepped on the accelerator, the best time selector system will automatically choose to shift, thereby eliminating the engine, clutch and transmission errors, to avoid the wrong bit shift. This is very important for both novice and vehicle reliability. Speed reducer greatly reduces the complexity of driving, so that AMT car driving more simple, worry, and to ensure the lowest power loss. By the selector to complete the driver to step on the clutch shift action, the timing of the shift is more accurate than the driver to complete. Therefore, the background for the growing shortage of energy and the emission of CO2 AMT under increasing pressure, conform to the "energy saving" this door, the best time selector system will automatically choose to shift, thereby eliminating the engine, clutch and transmission errors, to avoid the wrong change gear. This is very important for both novice and vehicle reliability. Speed reducer greatly reduces the complexity of driving, so that AMT car driving more simple, worry, and to ensure the lowest power loss. By the selector to complete the driver to step on the clutch shift action, the timing of the shift is more accurate than the driver to complete. Therefore, the background for the growing shortage of energy and the emission of CO2 AMT under increasing pressure, conform to the "energy saving" this door, the best time selector system will automatically choose to shift, thereby eliminating theengine, clutch and transmission errors, to avoid the wrong change gear. This is very important for both novice and vehicle reliability. Speed reducer greatly reduces the complexity of driving, so that AMT car driving more simple, worry, and to ensure the lowest power loss. By the selector to complete the driver to step on the clutch shift action, the timing of the shift is more accurate than the driver to complete. Therefore, the background for the growing shortage of energy and the emission of CO2 AMT under increasing pressure, conform to the "energy saving" this door, the best time selector system will automatically choose to shift, thereby eliminating the engine, clutch and transmission errors, to avoid the wrong change gear. This is very important for both novice and vehicle reliability. Speed reducer greatly reduces the complexity of driving, so that AMT car driving more simple, worry, and to ensure the lowest power loss. By the selector to complete the driver to step on the clutch shift action, the timing of the shift is more accurate than the driver to complete.3 electronically controlled hydraulic automatic transmission (AT)Electronic control of hydraulic automatic transmission (AT) in recent years, new technologies are constantly in use, it is moving toward multi block, digital control, etc.. Japan's largest automatic transmission manufacturer AISIN AW in 2006, the successful launch of model AA80E 8 speed automatic transmission (see Figure 3), is currently being used in the Lexus LS460 car. This will form a larger total transmission ratio, while the transmission ratio is also closer than the 5 speed transmission. Therefore, the driver can choose the best transmission ratio in almost all driving conditions. Electronic control module can choose more transmission ratio, the transmission ratio depends on the driving conditions, thereby reducing fuel consumption and improve the ride comfort. The optimal matching of engine speed and running state means that the engine improves the power and fuel economy and reduces the running noise.4 continuously variable transmission (CVT)Continuously variable transmission (CVT) is only two groups of removable cone and transmission belt or transmission chain, you can achieve the number of forward gear transmission process. The CVT drive to choose power transmission and the transmission ratio of the transmission chain and the variable cone groove width belt, when cone groove widthchanges, corresponding changes in the driving wheel and the driven wheel drive belt speed contact radius. CVT is a truly stepless, and AT compared with a high operating efficiency, low fuel consumption. Through the application of the market in recent years, the momentum of development is also relatively rapid, currently in our country has been applied to the rapid development of 5 models, more than 6 kinds of. Figure 4 shows the market outlook for the Chinese market in the next few years.At present, the world each big automobile manufacturers in order to improve the competitiveness of their products are vigorously engaged in research and development of CVT, equipped with CVT, TOYOTA, NISSAN car sales are FORD, GM, AUDI and other well-known car brands in the world, CVT's annual production has reached nearly 500 thousand vehicles. It is worth noting that, equipped with CVT car market, from the initial Japan, Europe has penetrated into the North American market, CVT has become the main trend of the development of today's automobile.5 dual clutch transmission (DCT)Dual clutch transmission (DCT) is the first German V olkswagen technology, so in theV olkswagen car system also known as DSG transmission. It can be said to be the world's most advanced, revolutionary transmission system, V olkswagen in 2002 in Wolfsburg, Germany for the first time to show the world the technological innovation. DSG transmission is designed to meet the consumer's desire to drive a sense of movement and fuel-efficient vehicles, for those who love the manual transmission drivers provide a best choice. DSG brings in low fuel consumption and vehicle performance without any loss, also has excellent acceleration and top speed, and the same with the traditional automatic transmission can realize smooth shift without affecting the traction force. Therefore, not only ensures the comfort, but also embodiesDynamic acceleration.Two, the development trend of transmissionAccording to industry estimates, statistical data will be the 2013 European transmission market changes, equipped with a manual transmission car will account for 52%, equippedwith automatic manual transmission will account for 10%, equipped with CVT will account for 2%, equipped with dual clutch transmission will account for 16%, equipped with automatic transmission will account for 20%. But industry experts have pointed out that the prediction was based on the transmission type of the existing new transmission products are constantly in the development process, so in the future transmission car market may also have some changes.1 automatic transmission to multi block developmentWith the automatic transmission car quantity rise, automatic transmission technology has evolved from the past traditional simple 4 speed electronic control (3 solenoid valve) to today's 6, 7, 8 (multi speed solenoid valve control) of the fuzzy control and network control logic. In recent years, the trend of increasing the number of automatic transmission is very obvious, from the traditional 4 speed to the 5, 6, 7, speed. Block number increase means that the total transmission ratio in the range widening, and two adjacent block between the transmission ratio and closer, so the shift time will be in advance, and in the launch to ensure the fuel economy, but also meet the acceleration performance. Now, the world's largest automatic transmission manufacturers have launched more than 5 speed multi speed automatic transmission, such as Z F's 6HP series AISIN; AW company U151/U250E,TF-60SN and TR-60SN; JATCO company's J F506E transmission G M company; T40E,6L50/80E etc..2 mechanical structure gradually simplifiedAlthough the new type of transmission block number in the number, but it does not mean that the transmission of the whole structure and volume become complex and increase, this is because of the combination of mechanical components from a large number of shift actuator control multiple planetary gear to achieve a simple 4 1 variable function, the development of today's 5 shift execution the so-called "Laipeilaijie element control type planetary gear set by logic combination can achieve 6 top 1 down transmission function. The number of parts is reduced by half, and the 6hp series reducer produced by ZF is an example (see Figure 7). At present, the German ZF company and Japan AISIN AW company has successfully pushed the 8 speed automatic transmission, but the gear part is still in use for gear, thus we will find outwhether the traditional Simpson series and Lavinia, or today's Laipeilaijie type planetary gear, are composed of "single planetary gear set single row gear and single row double gear" two forms. To this end, as long as we are familiar with the two kinds of planetary gear transmission on the OK, and when we go to analyze the production of different companies 5, 6, 7, block change.3 electronic control humanizationIn the mechanical and hydraulic aspects seem to be more and more simplified structure, less components, valve number is less, but in the overall control of the electronic control method has become more and more complicated, and requires more precise control, especially in the coordinated torque control, safety control, fuzzy logic control, overlapping shift control others of the more obvious. In order to improve the shift quality, reflect the driving comfort, the engine must realize the torque coordinated control of shift process of automatic transmission, the engine is mainly through the instant change of fuel injection quantity and the ignition delay function to maintain a smooth transition in the shift performance of the shift process of automatic transmission; safety protection control mainly refers to the failure of automatic transmission machinery hydraulic, electronic control, and the fault can be a greater threat to the transmission, in order to protect the transmission from further damage, protected by an automatic transmission through the computer receives the sensor information after the start; fuzzy logic control function, it is a microcomputer to imitate human brain function, can predict to the driver's next move, and finally realize the optimum shift time control and shift point switch Such control. Here we focus on understanding the overlapping shift control, this is because many of the maintenance staff is still relatively vague understanding. The so-called overlapping shift control this new words explanation is that shifting process is actually the process of friction friction element, in the common friction clutch and clutch or clutch and brake in the shift, if the friction torque of replacement process will cause improper timing, sharp fluctuations in output torque. The replacement of the friction torque between the two clutches or between the clutch and the brake, there will always be more or less interruption interval or overlap. Overlapping or excessive overlap, will produce undue shift impact. Overlap is the separation of the clutch to be separated too fast oil separation, to be combinedwith the clutch failed to establish sufficient oil pressure, thus the emergence of the two clutch torque transmission phenomenon. In this time of overlap, the output torque is first decreased too much, and then rise sharply, resulting in a larger torque disturbance. At the same time, the engine speed can not get a smooth transition, the first is due to the reduction of load growth, but also because of the rapid increase in load and speed down. Overlap is too much in the combination of the clutch has been able to transmit a lot of torque, the clutch should be separated from the oil separation is not very good, so there are two agencies working at the same time. In a short period of time, the two gears overlap, so that the engine and the output shaft are subject to braking, so the output shaft has a large torque disturbance. Subsequently, the clutch should be separated so that the transmission4 the number of actuators is increasing, and the type of control is changingYou will find that the automatic transmission actuator solenoid valve number increasing, the switch type solenoid valve is less, while the frequency is too much, the number of mechanical valve and control circuit is also less (more solenoid valve control is to improve the quality of the shift). A slide valve may be based on the conversion of the oil to achieve multi-purpose, a simple solenoid valve will be multi-purpose, it can achieve shift control, but also can take charge of oil pressure control. In the past the traditional type of electronic control automatic transmission, switching circuit is switched by shifting the solenoid valve to control the switching circuit, the circuit is a switching type (for shifting actuator junction without excessive vibration, the buffer control circuit is usually used in throttling and storage device to achieve slow control). The actuator in the 6HP series, the 6 has a pulse width modulation solenoid valve features high flow high frequency, 1 of them (E D S5) is mainly used to complete the system pressure regulating function, the other 1 (E D S6) is used to complete the engine and the transmission gearbox mechanical connection function (T C C) and the remaining 4 solenoid valve (E D S1-A, E D S2-B, E D S3-C, E D S4-E/D) respectively control 5 shift actuators of engagement and separation, that is to say the shift circuit controlled by the switch into the original regulation, thus greatly improve the shift quality. Shift control, but also can undertake the oil pressure control. In the past the traditional type of electronic control automatic transmission, switching circuit is switched by shifting thesolenoid valve to control the switching circuit, the circuit is a switching type (for shifting actuator junction without excessive vibration, the buffer control circuit is usually used in throttling and storage device to achieve slow control). The actuator in the 6HP series, the 6 has a pulse width modulation solenoid valve features high flow high frequency, 1 of them (E D S5) is mainly used to complete the system pressure regulating function, the other 1 (E D S6) is used to complete the engine and the transmission gearbox mechanical connection function (T C C) and the remaining 4 solenoid valve (E D S1-A, E D S2-B, E D S3-C, E D S4-E/D) respectively control 5 shift actuators of engagement and separation, that is to say the shift circuit controlled by the switch into the original regulation, thus greatly improve the shift quality.自动变速器发展现状及趋势一、变速器简介1.手动变速器(MT)大家知道,手动变速器是汽车中最常见的变速器之一,其基本原理是用几根平行轴及若干相啮合的直齿或斜齿齿轮进行动力传递,即由输入轴、轴出轴和中间轴构成变速器的主体,再加上一根倒挡轴及同步器等部件。
附录From 1894, a French engineer to a car fitted with the world's first transmission date, transmission has been car a hundred years of development. Important for the automotive transmission component of the commitment to enlarge the engine torque, torsional characteristics of reactive power with the engine, to achieve the desired power transmission, and thus adapt to various road conditions to achieve the main devices driving.The first is the use of manual transmission. Later, for the convenience of motorists, in the collar between adjacent gear fitted with a synchronizer, the synchronizer rely on, and we do not need to shift to judge the speed. Manual transmission is still present in the automotive industry a wide range of applications, automatic transmission is a trend, but the manual transmission is great fun, embodied persons.The traditional gear transmission with the use of different shift achieved the purpose of twisting, but with the change of gear by foot only hand-off to achieve, and this is the so-called manual transmission. Easily shift to achieve the abolition of clutch pedal and manual the AT (AutomaticTransmission) transmission occurred, it is the main browser using hydraulic Torque traditional mechanical gearbox with the shift function to achieve. In fact, as early as the 1948 Oldsmobile car GM has already emerged on the automatic transmission is now taking shape, but then the automatic transmission is only the addition of hydraulic coupler manual transmission only.AT used because earlier, so the English name is called "automatic transmission." However, AT is not the same as in the automatic transmission. As long as we can to achieve the automatic transmission shift automatic transmission can be called, it is necessary to achieve this in fact means a lot: In addition to AT, but also includes other forms of CVT. However, before the overthrow of the name can not, so let us not think so: automatic transmission (AT) including: hydraulic transmission (AT), Electronically Controlled Transmission (ECT), non-polar transmission (CVT).1908 Ford Model T the first use of a two-speed ratio automatic transmission. Constructed using multiple sets of gear, and gear into the central and peripheral gear, the outside is a runner, with the introduction of the central gear of the torque from the engine is different from camera gear groups so as to be different levels of speed, including Reverserotation reversing file. Runner-type automatic transmission, there is a drawback, that is, when people start to accelerate there is a feeling of spin the wheels, so drivers will be meng refueling door, but does not immediately increase the speed again. At present, some manufacturers such as Nissan and Fiat, have recourse to some electronic device to try to eliminate this shortcoming, Nissan Primera and the 6-speed transmission Fiat Punto 7-speed gearbox is the result of this effort. Drivers pulled no need to handle, they can easily change the speed.Although the automatic transmission continue to evolve and progress, but there will always be a drawback, that is, the response speed of action and between the pedal there will always be a gap, driving in the impression of a lack of intuition. Appeared in 1969 and the electronic control systems appeared in 1982, which was to improve digital technology. With the engine fuel injection and ignition devices continued to be refined, automatic transmission is also new tricks, such as set up a "campaign-style 'or" snow road ", such as the manipulation of different ways, some in the instrument panel has a bearing S letter button, you can become extremely rapid acceleration; or snowflake patterns are printed on the button on behalf of the snow moving to avoid slipping in the start. Even worse, a new generation of "adaptable style" Transmission can also adapt to motorists different habits, the corresponding reaction, so that drivers will become more user-friendly. the intelligent automatic transmission, and spread to the vehicle mass, which is a credit to the French. in 1997 with the Renault Clio Peugeot 206 took the lead in the most advanced computer-controlled technology and is known as "fuzzylogie" the principle that "fuzzy logic." This car can drive based on the temperament, road conditions, vehicle load and the surrounding environment and other factors, in the nine kinds of programs select the most suitable function, the realization of intelligent driving, in order to give full play to the vehicle performance and reduce fuel consumption and ensure safety. now that is, continuously variable transmission CVT (ContinuouslyVariableTransmission) also have been widely used, continuously variable transmission system in the non-use of gears, to provide smooth and "no class" conversion ratio of the transmission system at the same time light weight, small size, the characteristics of small parts, is recognized as the ideal vehicle transmission. compared to AT, CVT transmission wuji primarily in the drive way there different. The latter is the use of drive belts and the work of the main variable diameter driven wheel to transfer power line in order to achieve the continuous transmission ratiochange.However, the traditional CVT technical weaknesses exist, such as the transmission belt easily damaged, can not afford a larger load, etc., makes the transmission has been used in more than a small displacement, low-power vehicles. As technology advances, the energy crisis triggered a global energy conservation and environmental protection awareness, at the conclusion of the first generation of CVT based on the experience, people develop a better performance, greater torque capacity CVT. However, playing in the torque requirements on the CVT model is still unable to take on heavy responsibilities.Continuously Variable Transmission and the common development of electronically controlled automatic transmission also ushered in DSG (dual clutch automatic transmission) the popularity of Volkswagen has now started to apply only to the super sports car before the technology is applied to the ordinary family car has been up. DSG automatic transmission shifting technology enables faster, less power loss, so more fuel-efficient.The development of automatic transmission car seems to have wisdom, and even more good than people think. It changes according to the road outside, after the calculation, instead of smart people to make an accurate decision.距1894年,一个法国工程师给一辆汽车装上世界上第一个变速器至今,汽车变速器已经经过了一百多年的发展。
汽车变速器的设计外文文献翻译、中英文翻译、外文翻译A manual n。
also known as a standard n。
XXX。
It consistsof gears。
synchros。
roller bearings。
shafts。
and gear selectors。
The main clutch assembly is used to engage and disengage the engine from XXX gears are used to select the desired。
and the sector fork moves gears from one to another using the gearshift knob。
Synchros are used to slow the gear to a。
before it is XXX。
The counter shaft holds the gears in place and against the main input and output shaft。
Unlike automatic ns。
XXX。
as there isno XXX。
Note: XXX "n Shifter" was deleted as it had no XXX.)XXX have four to six forward gears and one reverse gear。
However。
some cars may have up to eight forward gears。
while semi trucks XXX by the number of forward gears。
such as a 5-speed standard n.The n of a standard n includes three shafts: the input shaft。
毕业设计外文翻译THE RESEARCHS OFAMT SHIFTING SCHEDULESThe modern automatic transmission is by far,the most complicated mechanical component in today`s automobile.It is a type of transmission that sifts itself.A fluid coupling or torque converter is used instead of a manually operated clutch to connect the transmission to the engine.There are two basic types of automatic transmission based on whether the vehicle is rear wheel drive or front wheel drive.On a rear wheel drive car,the transmission is usually mounted to the back of the engine and is located under the hump in the center of the floorboard alongside the gas pedal position.A drive shaft connects the transmission to the final drive which is located in the rear axle and is used to send power to the rear wheels.Power flow on this system is simple and straight forward going from the engine,through the torque converter,then trough the transmission and drive shaft until it reaches the final drive where it is split and sent to the two rear transmission.On a front wheel drive car,the transmission is usually combined with the final drive to form what is called a transaxle.The engine on a front wheeldrive car is usually mounted sideways in the car with the transaxle tucked under it on the side of the engine facing the rear of the car.Front axles are connected directly to the transaxle and provide power to front wheels.In this example,power floes from the engine,through the torque converter to a larger chain that sends the power through a 180 degree turn to the transmission that is along side the engine.From there,the power is routed through the transmission to the final drive where it is split and sent to the two front wheels through the drive axles.There are a number of other arrangements including front drive vehicles where the engine is mounted front to back instead of sideways and there are other systems that drive all four wheels but the two systems described here are by far the most popular.A much less popular rear and is connected by a drive shaft to the torque converter which is still mounted on the engine.This system is found on the new Corvette and is used in order to balance the weight evenly between the front and rear wheels for improved performance and handling.Another rear drive system mounts everything,the engine,transmission and final drive in the rear.This rear engine arrangement is popular on the Porsche。
附录附录A电控机械式自动变速器(AMT)是在传统的手动齿轮式变速器基础上改进而来的;它揉合了 AT(自动)和 MT(手动)两者优点的机电液一体化自动变速器;AMT既具有液力自动变速器自动变速的优点,又保留了原手动变速器齿轮传动的效率高、成本低、结构简单、易制造的长处。
它揉合了二者优点,是非常适合我国国情的机电液一体化自动变速器。
它是在现生产的机械变速器上进行改造的,保留了绝大部分原总成部件,只改变其中手动操作系统的换档杆部分,生产继承性好,改造的投入费用少,非常容易被生产厂家接受。
它的缺点是非动力换档,这可以通过电控软件方面来得到一定弥补。
在几种自动变速器中,AMT的性价比最高。
AMT用先进的电子技术改造传统的手动变速器,不仅保留了原齿轮变速器效率高、低成本的长处,而且还具备了液力自动变速器采用自动换档所带来的全部优点。
它以特有的经济、方便、安全、舒适性而备受所有驾驶者的欢迎,成为各国开发的热点。
驾驶员通过加速踏板和操纵杆向电子控制单元(ECU)传递控制信号;电子控制单元采集发动机转速传感器、车速传感器等信号,时刻掌握着车辆的行驶状态;电子控制单元(ECU)根据这些信号按存储于其中的最佳程序,最佳换档规律、离合器模糊控制规律、发动机供油自适应调节规律等,对发动机供油、离合器的分离与结合、变速器换档三者的动作与时序实现最佳匹配。
从而获得优良的燃油经济性与动力性能以及平稳起步与迅速换档的能力,以达到驾驶员所期望的结果。
AMT是对传统干式离合器和手动齿轮变速器进行电子控制实现自动换档的新式变速器,其控制过程基本是模拟驾驶员的操作。
控制单元(ECU)的输入有:驾驶员的意图-加速踏板、档位选择;汽车的工作状态-发动机转速、节气门开度、车速等。
控制单元(ECU)根据换档规律、离合器控制规律、发动机节气门自适应调节规律产生的输出,对节气门开度、离合器、换档操纵三者进行综合控制,有效配合。
AMT由于继承了齿轮传动固有的传动效率高、机构紧凑、工作可靠等优点,并可以实现手动和自动两种模式选择,因此有较强的可靠性和适应性。
TRANSMISSIONOf all transmission technologies, the manual gearbox is the most efficient; around 96 per cent of the energy that is put in comes out of the other end. But not everyone can drive one or wants to. Because you have to dip the clutch pedal, it is less comfortable to drive in heavy traffic. It makes the driver tired and the torque interruptions’ head-nod effect on passengers can be wearing.The driver's clutch control and corresponding torque interruptions are also the manuals weak point. When accelerating up through the gearbox, each up-shift requires the driver to cut the torque momentarily by lifting the gas pedal and dipping the clutch. It may just take a second to complete the operation, but during this time the vehicle is losing speed and acceleration.At the opposite end of the spectrum is the traditional automatic. The modern transmission is by far, the most complicated mechanical component in today’s automobile. It is a type of transmission that shifts itself .A fluid coupling or torque converter is used instead of a manually operated clutch to connect the transmission to the engine.There are two basic types of automatic transmissions based on whetherthe vehicle is rear wheel drive . On a rear wheel drive car , the transmission is usually mounted to the back of the engine and is located under the hump in the center of the floorboard alongside the gas pedal position . A drive shaft connects the rear of the transmission to the final drive which is located in the rear axle and is used to send power to the rear wheel. Power flow on this system is simple and straight forward going from the engine, through the torque converter , then through the transmission and driver shaft until it reaches the final driver where it is split and sent to the two rear wheel .On a front wheel drive car, the transmission is usually combined .With the final drive to from what is called a transaxle. The engine on a front wheel driver car is usually mounted sideways in the car with the transaxle tucked under it onthe side of the engine facing the rear of the car. Front axles are connected directly to the transaxle and provide power to the front wheels. In this example, power flows from the engine through the torque converter to a large chain that sends the power through a 180 degree turn to the transmission that is along side the engine. From there,The power is routed through the transmission to the final drive where it is split and sent to the two front wheels through the drive axles.There are a number of other arrangements including front drive vehicles where the engine is mounted front to back instead of sideways and there are other systems that drive all four wheels but the two systems described here are by far the most popular. A must less popular rear drive arrangement has the transmission mounted to the final drive at the rear and is connected by a drive shaft to the torque converter which is still mounted on the engine. This system is found on the new corvette and is used in order to balance the weight evenly between the front and rear wheels for improved performance and handling. Another rear drive system mounts everything, the engine, transmission and final drive in the rear. This rear engine arrangement is popular on the Porsche.The modern automatic transmission consists of many components and systems that are designed to work together in a symphony of planetary gear sets, the hydraulic system, seals and gaskets, the torque converter, the governor and the modulator or throttle cable and computer consider being an art form.On the automobile planet gear mainly uses in two places, one is the driving axle reduction gear, two is the automatic transmission. Very many net friends all want to know that, the planet gear has any function, why automobile must have it . We knew very well the gear major part all rotates the spool thread fixed gear. For example mechanical type clock and watch, above all gears although all in make the rotation, but their rotation center (with center of a circle position superposition) often installs through the bearing on the cabinet, therefore, their rotating axis all is the relative cabinet fixed, thus also is called "dead axle gear" . Has must have surely moves, the corresponding place, some kind of not that manner knows very well is called "planet gear" the gear, their rotation spool thread is not fixed, but is installs the support which may rotate in (blue color) on(in chart black part is shell, yellow expression bearing). The planet gear (green) besides can look like the dead axle gear such to revolve own rotating axis (B-B) to rotate, their rotating axis also (is called planet) along with the blue color support to circle other gears the spool thread (A-A) to rotate. Circles oneself spool thread the rotation to be called "rotation", circles other gear spool threads the rotation to be called "revolution", looks like in solar system planet such, therefore acquires fame.The spool thread fixed gear drive principle is very simple, meshes mutually in a pair in the gear, some gear takes the driving pulley, the power spreads from its there, another gear takes the driven wheel, the power outputs from it toward outside. Also some gears only take the stopover station, at the same time meshes with the driving pulley, one side meshes in addition with the driven wheel, the power passes from its there.In contains the planet gear in the gear system, the situation was different. Because has the planet frame, in other words, may have three rotating axes permissions power input/Output, but also may use the coupling or the brake and so on method. in needs time limits axis the rotation, is left over two axes to carry on the transmission, as the matter stands, meshes mutually between the gear relations may have the many kinds of combinations: The power from sun gear input, outputs from other sun gear, the planet put through brake mechanism has checked dies; Power from sun gear input, from planet output, moreover a sun gear ecks dies; The power from a planet input, outputs from sun gear, moreover a sun gear checks dies; Two powers separately from two sun gears inputs, after synthesis from planet output; Two powers separately from the planet and sun gear input, after the synthesis output from other sun gear; The power from sun gear input, divides two groups outputs from other sun gear and the planet frame; The power from a planet input, divides two groups to output from two sun gears;Its shift quality is good thanks to its torque converter, but efficiency is relatively poor despite recent advances. Because of this, a lot of the current research is trying to find an efficient alternative to the conventional automatic.The main technologies are continuously variable transmissions (CVTs); dualclutch transmissions (DCTs) and automated manual transmission (AMTs).They all offer different benefits over the conventional planetary automatic.The CVT uses a belt chain or torodial shaped dish drive to vary an infinite number of gear ratios. It has improved efficiency and cost when compared to conventional automatics. Its advantage comes from its simplicity. It consists of very few components;usually a rubber or metal-link belt;a hydraulically operated driving pulley, a mechanical torque-sensing driving pulley, microprocessors and some sensors.The transmission works by varying the distance between the face of the two main pulleys. The pulleys have V-shaped grooves in which the connecting the belt rides. One side of the pulley is fixed axially; the other side moves, actuated by hydraulics.When actuated, the cylinder can increase or reduce the amount of space between the two sides of the pulley. This allows the belt to ride lower or higher along the walls of the pulley, depending on driving conditions. This changes the gear ratio. A torodial-type design works in a similar way but runs an discs and power- rollersThe "step less" nature of its design is CVT's biggest draw for automotive engineers .Because of this, a CVT can work to keep the engine in its optimum power range, thereby increasing efficiency and mileage. A CVT can convert every point on the equine’s operating curve to a corresponding point on its own operating curve.The transmission is most popular with Japanese carmakers and Japanese supplier JATCO is a major producer. But in the US and Europe driving styles are different. Uptake has been slow despite Audi and other manufacturers having Offered CVT operations on their ranges.The DCT is, in effect, two manual gearboxes coupled together. Gear shifts are made by switching from one clutch on one gearbox to another clutch on the other. The shift quality is equal to a conventional automatic, but slip, fluid drag and hydraulic losses in the system result in only slightly improved efficienc y and acceleration over the conventional planetary automatic. Developing the controlstrategy is costly too."Resent advances in conventional automatic technology have weakened the argument to develop and set up production for CVT or DCT," says Bill Martin, managing director of transmission firm Zeroshift "Some carmakers have cancelled DCT projects because of the cost."The cheapest way to build an automatic is with an AMT. AMTs use actuators to replace the clutch pedal and gear stick of a conventional manual. They keep the high efficiency and acceleration of a manual gearbox, but the shift quality on some models is lacking. Torque interruptions and the head-nod effect are the most common complaint.SO what is the alternative? There are always new ideas in transmissions, but Zeroshift says that its technology has efficiency benefits over a manual, delivering fuel economy improvements to city driving. Shift quality can also be equal to that of a refined automatic.Zeroshift's approach is an upgrade to the AMT. The synchromesh is replaced with an advanced dog engagement system.Dog engagement has been used for many years in motor sport to allow fast shifts. Conventional dog Boxes are unsuitable for road use as the large spaces between the drive lugs or 'dogs" create backlash, an uncomfortable shunt caused by the sudden change in torque direction.Zeroshift's technology solves this problem by adding a second set of drive dogs. It has also made each of The two sets of dogs only capable of transmitti ng torque in one or other opposing directions错误!未找到引用源。
How Automatic Transmissions WorkIf you have ever driven a car with an automatic transmission, then you know that there are two big differences between an automatic transmissionand a manual transmission:There is no clutch pedal in an automatic transmission car.There is no gear shift in an automatic transmission car. Once you put the transmission into drive, everything else is automatic.Both the automatic transmission (plus its torque converter) and a manualtransmission (with its clutch) accomplish exactly the same thing, but they do it in totally different ways. It turns out that the way an automatic transmission does it is absolutely amazing!In this article, we'll work our way through an automatic transmission. We'll start with the key to the whole system: planetary gearsets. Then we'll see how the transmission is put together, learn how the controls work anddiscuss some of the intricacies involved in controlling a transmission. Some BasicsJust like that of a manual transmission, the automatic transmission's primary job is to allow the engine to operate in its narrow range of speeds while providing a wide range of output speeds.Without a transmission, cars would be limited to one gear ratio, and that ratio would have to be selected to allow the car to travel at the desired top speed. If you wanted a top speed of 80 mph, then the gear ratio would be similar to third gear in most manual transmission cars.You've probably never tried driving a manual transmission car using only third gear. If you did, you'd quickly find out that you had almost no acceleration when starting out, and at high speeds, the engine would be screaming along near the red-line. A car like thiswould wear out very quicklyand would be nearly undriveable.So the transmission uses gears to make more effective use of the engine's torque, and tokeep the engine operating at an appropriate speed. The key difference between a manual and an automatic transmission is that the manual transmission locks and unlocks different sets of gears to the output shaft to achieve the various gear ratios, while in an automatic transmission, the same set of gears produces all of the different gear ratios. The planetary gearset is the device that makes this possible in an automatic transmission.GearsThis automatic transmission uses a set of gears, called a compound planetary gearset, that looks like a single planetary gearset but actuallybehaves like two planetary gearsets combined. It has one ring gear that is always the output of the transmission, but it has two sun gears and two sets ofplanets.Let's look at some of the parts:First GearIn first gear, the smaller sun gear is driven clockwise by the turbine in the torque converter. The planet carrier tries to spin counterclockwise, but is held still by the one-way clutch (which only allows rotation in the clockwise direction) and the ring gear turns the output. The small gear has 30 teeth and the ring gear has 72, so the gear ratio is:Ratio = -R/S = - 72/30 = -2.4:1So the rotation is negative 2.4:1, which means that the output direction would be opposite the input direction. But the output direction is really the same as the input direction -- this is where the trick with the two sets of planets comes in. The first set of planets engages the second set, and the second set turns the ring gear; this combination reverses the direction. You can see that this would also cause the bigger sun gear to spin;but because that clutch is released, the bigger sun gear is free to spin in the opposite direction of the turbineSecond GearThis transmission does something really neat in order to get the ratio needed for second gear. It acts like two planetary gearsets connected to eachother with a common planet carrier.The first stage of the planet carrier actually uses the larger sun gear as the ring gear. So the first stage consists of the sun (the smaller sun gear), the planet carrier, and the ring (the larger sun gear).The input is the small sun gear; the ring gear (large sun gear) is held stationary by the band, and the output is the planet carrier. so the formula is:1 + R/S = 1 + 36/30 = 2.2:1The planet carrier turns 2.2 times for each rotation of the small sun gear. At the second stage, the planet carrier acts as the input for the second planetary gear set, the larger sun gear (which is held stationary) acts as the sun, and the ring gear acts as the output, so thegear ratio is:1 / (1 + S/R) = 1 / (1 + 36/72) = 0.67:1To get the overall reduction for second gear, we multiply the first stage by the second, 2.2 x 0.67, to get a 1.47:1 reduction. This may sound wacky, but it works.Third GearMost automatic transmissions have a 1:1 ratio in third gear. You'll remember from the previous section that all we have to do to get a 1:1 outputis lock together any two of the three parts of the planetary gear.With thearrangement in this gearset it is even easier -- all we have to do is engage the clutches that lock each of the sun gears to the turbine.If both sun gears turn in the same direction, the planet gears lockup because they can only spin in opposite directions. This locks the ringgear to the planets and causes everything to spin as a unit, producing a 1:1 ratio. OverdriveBy definition, an overdrive has a faster output speed than input speed.It's a speed increase. In this transmission, engaging the overdrive accomplishes two things at once. If you read How Torque Converters Work, you learned about lockup torque converters. In order to improve efficiency, somecars have a mechanism that locks up the torque converter so that the output of the engine goes straight to the transmission.In this transmission, when overdrive is engaged, a shaft that is attached to the housing of the torque converter (which is bolted to the flywheel of the engine) is connected by clutch to the planet carrier. The small sun gear freewheels, and the larger sun gear is held by the overdrive band. Nothing is connected to the turbine; the only input comes from the converter housing. Let's go back to our chart again, this time with the planet carrierfor input, the sun gear fixed and the ring gear for output.Ratio = 1 / (1 + S/R) = 1 / ( 1 + 36/72) = 0.67:1So the output spins once for every two-thirds of a rotation of the engine. If the engine is turning at 2000 rotations per minute (RPM), the outputspeed is 3000 RPM. This allows cars to drive at freeway speed while theengine speed stays nice and slow.ReverseReverse is very similar to first gear, except that instead of the small sun gear being driven by the torque converter turbine, the bigger sun gear is driven, and the small one freewheels in the opposite direction. The planet carrier is held by the reverse band to the housing. So, according to our equations from the last page, we have:Ratio = -R/S = 72/36 = 2.0:1So the ratio in reverse is a little less than first gear in this transmission.Gear RatiosThis transmission has four forward gears and one reverse gear. Let's summarize the gear ratios, inputs and outputs:Hydraulic SystemThe automatic transmission in your car has to do numerous tasks. You may not realize how many different ways it operates. For instance, here are some of the features of an automatic transmission:•If the car is in overdrive (on a four-speed transmission), the transmission will automatically select the gear based on vehiclespeed and throttle pedal position.•If you accelerate gently, shifts will occur at lower speeds than if you accelerate at full throttle.•If you floor the gas pedal, the transmission will downshift to the next lower gear.•If you move the shift selector to a lower gear, the transmission will downshift unless the car is going too fast for that gear. If the car isgoing too fast, it will wait until the car slows down and thendownshift.•If you put the transmission in second gear, it will never downshift or upshift out of second, even from a complete stop, unless youmove the shift lever.•You've probably seen something that looks like this before. It is really the brain of the automatic transmission, managing all ofthese functions and more. The passageways you can see route fluidto all the different components in the transmission. Passagewaysmolded into the metal are an efficient way to route fluid; withoutthem, many hoses would be needed to connect the various parts ofthe transmission. First, we'll discuss the key components of thehydraulic system; then we'll see how they work together.The PumpAutomatic transmissions have a neat pump, called a gear pump. The pump is usually located in the cover of the transmission. It draws fluid from a sump in the bottom of the transmission and feeds it to the hydraulic system. It also feeds the transmission cooler and the torque converter.The inner gear of the pump hooks up to the housing of the torque converter, so it spins at the same speed as the engine. The outer gear is turned by the inner gear, and as the gears rotate, fluid is drawn up from the sump on one side of the crescent and forced out into the hydraulic system on the other side.The GovernorThe governor is a clever valve that tells the transmission how fast the car is going. It is connected to the output, so the faster the car moves, the faster the governor spins. Inside the governor is a spring-loaded valve that opens in proportion to how fast the governor is spinning -- the faster the governor spins, the more the valve opens. Fluid from the pump is fed to the governor through the output shaft.The faster the car goes, the more the governor valve opens and the higher the pressure of the fluid it lets through.Valves and ModulatorsThrottle Valve or ModulatorTo shift properly, the automatic transmission has to know how hard the engine is working. There are two different ways that this is done. Some cars have a simple cable linkage connected to a throttle valve in the transmission. The further the gas pedal is pressed, the more pressure is put on the throttle valve. Other cars use a vacuum modulator to apply pressure to the throttle valve. The modulator senses the manifold pressure, whichdrops when the engine is under a greater load.Manual ValveThe manual valve is what the shift lever hooks up to. Depending on which gear is selected, the manual valve feeds hydraulic circuits thatinhibitcertain gears. For instance, if the shift lever is in third gear, it feeds a circuit that prevents overdrive from engaging.Shift ValvesShift valves supply hydraulic pressure to the clutches and bands to engage each gear. The valve body of the transmission contains severalshift valves. The shift valve determines when to shift from one gear to the next. For instance, the 1 to 2 shift valve determines when to shift fromfirst tosecond gear. The shift valve is pressurized with fluid from the governor on one side, and the throttle valve on the other. They are supplied with fluid by the pump, and they route that fluid to one of two circuits to control which gear the car runs in.The shift valve will delay a shift if the car is accelerating quickly. If the car accelerates gently, the shift will occur at a lower speed. Let's discuss what happens when the car accelerates gently.As car speed increases, the pressure from the governor builds. This forces the shift valve over until the first gear circuit is closed, and the second gear circuit opens. Since the car is accelerating at light throttle, the throttle valve does not apply much pressure against the shift valve.When the car accelerates quickly, the throttle valve applies more pressure against the shift valve. This means that the pressure from the governor has to be higher (and therefore the vehicle speed has to be faster) before the shift valve moves over far enough to engage second gear.Each shift valve responds to a particular pressure range; so when thecar is going faster, the 2-to-3 shift valve will take over, because the pressure from the governor is high enough to trigger that valve. Electronic ControlsElectronically controlled transmissions, which appear on some newer cars, still use hydraulics to actuate the clutches and bands, but each hydraulic circuit is controlled by an electric solenoid. This simplifies the plumbing on the transmission and allows for more advanced control schemes.自动变速器如何工作如果你曾经驾驶过一辆带着自动变速器的车, 那么你就知道自动变速器和手动变速器之间有很大的不同:在一个带着自动变速器的汽车中没有离合器踏板。