Automotive Brake NVH 汽车制动NVH
Seong K. Rhee
SKR Consulting, LLC
Introduction to Brake Noise & Vibration
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L. F. Squeal 低频尖叫声
High Frequency Squeal 高频尖叫声
Frequency 频率(HZ)
Groan 低沉噪音Moan 低沉噪音
Roughness 粗糙度(5 -60 Hz) DTV
Frequency Range for Disc Brake Noise
and Vibration
盘式制动器的噪音和振动的频率范围
Introduction to Brake Noise & Vibration
SOUND 声音
Rapidly fluctuating air pressure caused by
vibrating surface
由表面振动引起的空气压力的迅速振荡
HIGH FREQUENCY SQUEAL
高频尖叫声
Caused by Vibration of Disc
由制动盘振动引起
Introduction to Brake
Noise & Vibration
Introduction to Brake Noise & Vibration
LOW FREQUENCY SQUEAL
低频尖叫声Caused by Vibration of Caliper Body,
Anchor Bracket, or Knuckle 由卡钳,挂钩或者关节的振动引起
Vibration Excitation Of Disc/Caliper Assembly
制动盘/卡钳总成振动的激发
z Caused by Pad and Backing Plate Vibration/Impact
z由刹车片和钢背的振动/冲击引起
z Pad-Disc Modal Coupling
z刹车片和刹车盘的结合方式
z Backing Plate-Caliper Interactions
z钢背和卡钳的相互作用
z Contact Pressure Distribution
z接触压力的分配
Introduction to Brake
Noise & Vibration
Practical Squeal Solutions; Excitation vs. Response
实际尖叫的解决办法;激发和响应
z De-Coupling of Disc, Pad and Caliper
z判定耦合的因素:制动盘,刹车片和卡钳的
z Damped Disc 软质制动盘
z Damped Pad 软质刹车片
z Pad Chamfer 刹车片倒角
z Lower Friction (Humidity) 低摩擦系数(湿度)
z No Metal Pick-up on Pad (Lubricants) 刹车片无金属(润滑剂)
Introduction to Brake
Noise & Vibration
Practical Squeal Solutions; Excitation vs. Response
实际尖叫的解决办法;激发和响应
z Anti-Noise Shim and Clip 消音片和夹子
z Smooth Sliding of Pad Assembly 刹车片总成流畅滑动
z Flatness of Backing Plate 钢背的平面
z Caliper Design for Uniform Contact Pressure 均匀接触压力的卡钳设计z Part Variability Reduction (Modals) 部分可变性的减少(程式)
Introduction to Brake
Noise & Vibration
Introduction to Brake Noise & Vibration
Brake Squeal 制动尖叫声
z
Brake squeal is a phenomenon of dynamic instability that occurs at one or more of the natural frequencies of the brake system.
z 制动尖叫声是一种动态不稳定性现象，发生于制动系统的一个或者更多的固有频率上。z The excitation comes from the friction couple. 受摩擦力偶激发。
z Pads and rotor coupling has major impact on mid to high frequency (4 ~ 16 kHz) squeal. z
刹车片和刹车盘接合主要产生中等到高频(4 ~ 16 kHz)尖叫声。
-The disc rotor is acting like a “speaker”(sound wave radiated from the rotor surfaces).
-
刹车盘类似于一个喇叭（声波从刹车盘表面辐射开去）。
z
Low frequency (1 ~ 4 kHz) squeal typically involves caliper, anchor bracket, knuckle and suspension, in addition to pads and rotor.
z
低频(1 ~ 4 kHz) 尖叫除了来自于刹车片和刹车盘外，主要来自卡钳，挂钩，关节和悬挂。
Introduction to Brake Noise & Vibration
影响低频制动噪音的因素
Thickness Vane pattern Hat section Material
Rotor Bridge Anchor bracket
Clips Rail slippers
Caliper
Stiffness/mass
Knuckle Stiffness/mass Damping
Suspension Mu level/variation
Material Geometry Insulator
Pad
Low frequency brake
Introduction to Brake Noise & Vibration
影响高频制动噪音的因素
Thickness Vane pattern Hat section Material
Rotor Mu level Material Geometry Insulator
Caliper Anchor bracket
Pad
High frequency squeal
Introduction to Brake Noise & Vibration
Vehicle Test 整车测试
z The ultimate judge for successful noise solutions. z 成功解决噪音问题的最终判断。
z
Test procedures 测试程序(North America 北美):
y Los Angeles City Traffic (LACT) -Standard brake noise and wear validation test; Different routes for each OE
y 洛杉矶市交通测试(LACT) –标准制动噪音和磨耗确认测试；对每个原装车辆不同路线的测试
y Detroit Suburban Traffic (DST) -Mainly for DTV y 底特律郊区交通测试(DST) –主要用于DTV 测试
y Other tests from different OEMs and suppliers -For noise investigation and quick validation
y
来自主机厂和供应商的其他测试–用于噪音研究和快速确认
z Driver’s noise ratings, noise counts, sound pressure and/or acceleration data are collected throughout the test.
z
驾驶员收集了整个测试过程中的噪音出现机率，噪音点，声音强度和/或加速度数据
Dynamometer Test 台架测试
z Provides noise validation within a controlled environment.
z在可以控制的环境下确认噪音。
z Lower cost and quicker to run than vehicle test.
z和整车测试比，成本低并且时间短。
z Test procedures 测试程序:
y SAE J2521 -Developed after AK with the addition of inertia stops
y SAE J2521 –AK测试基础上增加了增加了惯量制动
y AK -European originated procedure (mainly drag stops)
y AK –起源于欧洲的测试程序（主要拖曳制动）
y Simulated LACT -A series of stops similar to LACT driving conditions
y模拟LACT –一系列类似LACT驾驶条件的制动
y The combination of the above
y以上几种相结合的测试
z Sound pressure data are typically collected throughout the test.
z测试收集了整个过程有代表性的声音强度数据。
Introduction to Brake
Noise & Vibration
Introduction to Brake Noise & Vibration
Repeatability and Reproducibility
of Brake NVH Testing
制动NVH 测试的可重复性和再现性
z The underlining mechanisms of brake squeal involve multiple aspects in the brake system. It is not uncommon to face the following problems:
z
制动尖叫声关键的机理包括制动系统的方方面面。通常会见到以下问题：
y Correlation between vehicle and dynamometer tests y 整车和台架测试的关系
y Repeatability and reproducibility between vehicles or dynamometers y
整车和台架测试的可重复性和再现性
z Correlation is more difficult to achieve for low frequency squeal since more components come into play.
z 低频尖叫声更难完成分析，因为起作用的因素更多。
z Environmental factors such as weather, ambient temperature, humidity and road dust may also influence test results.
z 环境因素，例如：天气，周围的温度，湿度和陆上灰尘都可能影响测试结果。z Best practices to improve repeatability and reproducibility in brake NVH testing:z
提高制动NVH 测试可重复性和再现性的最佳操作是：
y Use the correct level of hardware 采用正确等级的硬件y Set the correct test parameters 设定正确的测试参数y Ensure consistency of test parts 确保测试组件的连贯性
y Document all variations and significant events during the test 记录测试中所有的变化和重要事件y
Properly collect and analyze data 适当的收集和分析数据
Introduction to Brake Noise & Vibration
Modal Test 程式测试
z
Provides understanding of structural dynamic characteristics of the components and brake system.
z 提供对部件和制动系统的结构动力学特性的理解
z
Component modal test measures natural frequencies, modal damping ratios, and/or mode shapes of pad, rotor, insulator, caliper, anchor bracket, knuckle, etc.
z
部件程式测试测量了固有频率，程式阻尼比，和/或刹车片，刹车盘，隔振体，卡钳，挂钩，关节等的模态振型。
z System modal test is conducted on brake system on vehicle or dynamometer. z 系统程式测试是制动系统导入到整车或者台架的测试。z Impact Hammer Test -quick and inexpensive.z 锤击测试–迅速而且不贵。
z Laser Vibrometer -more elaborate with expensive equipment. z
镭射振动计–更加精确且昂贵的设备。
y Mode shape determination 模态振型测试
y
Operating deflection shape (ODS) measurement 操作变形振型测量
Introduction to Brake Noise & Vibration
Brake Roughness Definition 制动粗糙度定义
z Brake Roughness is the vehicle vibration, jerkiness, or pulsation that is felt by the driver and or passenger:
z
制动粗糙度是指驾驶员或乘客能够感受到的整车振动，急停或者，悸动:
y During a braking stop 一次刹车期间y
Sensed through 整个过程中通过
8steering wheel (shake or nibble) 方向盘(颤抖)8floor boards or dash panel 底板或者仪表板
8car seat 座椅
8
brake pedal 刹车踏板
y Created by repetitive variation in torque output from the brake y
制动扭力输出造成的可重复变化
8typically in the 5-60hz range 8主要在在5-60hz 范围内
8frequency varies with wheel speed 8频率随着车轮转速改变
8typically 1 to 2 pulsations per revolution but can reach up to 108
每转一次会有1到2次悸动,但是可以增加到10次
Introduction to Brake
Noise & Vibration
Brake Roughness Definition (Cont’d) 制动粗糙度定义(继续)
z
Severity of roughness dependent on 粗糙度的严重程度由以下决定:
y Magnitude & Frequency of the brake torque variation y 制动转矩变化的大小和频率y Sensitivity of the vehicle y
车辆敏感性
8transmission path through suspension & steering components 8悬挂和转向组件的传输路径
8resonance frequency & damping of vehicle components 8
车辆组件的共振频率和阻尼
z Brake Roughness, also commonly called Judder or Shudder, is often tagged with a descriptor that helps define the conditions where the roughness is noticed:z
制动粗糙度也通常称作抖动或发抖, 通常贴上一个标签来帮助定义粗糙度的来源:
y Hot Roughness, Brake temperature > 250 C 热粗糙度, 制动温度> 250 C y Cold Roughness, Brake temperature < 100 C 冷粗糙度, 制动温度< 100 C y Wet Roughness, Water soaked 湿粗糙度, 制动温度,水浸湿y
High Speed Judder, > 160 kph 高速抖动, > 160 千米/小时
Introduction to Brake
Noise & Vibration
Judder
Pad Assy Pad Assy Dust Shield Dust Shield Hub / Bearing Hub / Bearing Friction Materials
Friction Materials Caliper
Caliper Rotor
Rotor Wheel / Tire Wheel / Tire Suspension
Suspension Vehicle Sensitivity
Vehicle Sensitivity Torque Variation
Compressibility
Lining Transfer
Abrasives
Lubricants
Mu Level
Resins
Corrosion
Mu Variation
Swell Scorch Seal Rollback Piston Material Slide Force Pin Clearance Bridge Stiffness Clamp Loads Centering Piston Clearance Taper Wear Residual Drag Metallurgy Runout -Dynamic Corrosion DTV Vane Pattern Thermal Distortions Plate Thickness
Surface Finish
Shoe Plate Insulator Attachment Clips
Chamfer Dimensional Tolerances Length
Wheel Hub Footprint Clamp Load Lug Nut Torque Tire Imbalance
Hub Flange
TIR Wobble
Static/Dynamic Runout Bearing Torque Knuckle
Flex Bushing Stiffness
Resonance's
Contamination
End Play
Runout -Static Machining Possible Contributors to Roughness 可能引起粗糙度的因素
ROTOR (DISC) RUNOUT
对偶(刹车盘)之间摩擦不均匀
?Major Factor for Rotor Thickness Variation
?影响对偶厚度变化的主要因素
?Rotor Friction Surface Parallel to Pad Friction Surface, and Separated from Each Other in Brake Assembly on Vehicle
?对偶摩擦面和刹车片摩擦面平行,并且在车辆制动总成中相互分开
Introduction to Brake
Noise & Vibration
Introduction to Brake Noise & Vibration
z
Lining Transfer 衬层转移z Thermally Induced Distortions / Growth 温度导致扭曲/变厚z Corrosion 腐蚀z Uneven Wear Patterns from Off-Braking / On-Braking Drag z 刹车结束或进行时不均匀的磨损
Uneven rotor wear caused by varying pad contact while driving at highway speed is the factor that usually has the most significant influence on creating brake
roughness. There can be selective wear on either one side of the rotor, or on both sides of the rotor.
当高速路上驾驶时,通常速度是造成制动粗糙度的最重要的因素,不均匀的磨损由刹车片接触面积变化造成。刹车盘的一面或者两面的磨损是有选择性的。
Rotor Thickness Variation in the range of 15-20 um (or about half the thickness of a human hair) can create torque variation in the range of 50 NM.This normally is sufficient to create vehicle roughness issues.
刹车盘在15~20微米(或者大约普通人头发一半的厚度）的厚度变化能够造成扭矩在50 NM 的范围变化。这个一般足以产生车辆粗糙度。
Contributors to Rotor Thickness Variation
可能引起刹车盘厚度变化的因素