1、Automotive Brake NVH 汽车制动NVH Seong K. Rhee SKR Consulting, LLCIntroduction to Brake Noise 激发和响应 De-Coupling of Disc, Pad and Caliper 判定耦合的因素:制动盘,刹车片和卡钳的 Damped Disc 软质制动盘 Damped Pad 软质刹车片 Pad Chamfer 刹车片倒角 Lower Friction (Humidity) 低摩擦系数( 湿度) No Metal Pick-up on Pad (Lubricants) 刹车片无金属( 润滑剂)Introduc
2、tion to Brake Noise Excitation vs. Response 实际尖叫的解决办法;激发和响应Introduction to Brake Noise & Vibration 9 Brake Squeal 制动尖叫声 Brake squeal is a phenomenon of dynamic instability that occurs at one or more of the natural frequencies of the brake system. 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。 The excitatio
3、n comes from the friction couple. 受摩擦力偶激发。 Pads and rotor coupling has major impact on mid to high frequency (4 16 kHz) squeal. 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）。 Low frequency (1 4
4、kHz) squeal typically involves caliper, anchor bracket, knuckle and suspension, in addition to pads and rotor. 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 10 Factors Influencing Low Frequency Brake Noise 影响低频制动噪音的因素 Thickness Vane pattern Hat section Materia
5、l Rotor Bridge Anchor bracket Clips Rail slippers Caliper Stiffness/mass Knuckle Stiffness/mass Damping Suspension Mu level/variation Material Geometry Insulator Pad Low frequency brakeIntroduction to Brake Noise & Vibration 11 Factors Influencing High Frequency Brake Noise 影响高频制动噪音的因素 Thickness Van
6、e pattern Hat section Material Rotor Mu level Material Geometry Insulator Caliper Anchor bracket Pad High frequency squealIntroduction to Brake Noise 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DT
7、V 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 Drivers noise ratings, noise counts, sound pressure and/or acceleration data are collected throughout the test. 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Introduction to Brake
8、 Noise & Vibration 13 Dynamometer Test 台架测试 Provides noise validation within a controlled environment. 在可以控制的环境下确认噪音。 Lower cost and quicker to run than vehicle test. 和整车测试比，成本低并且时间短。 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
9、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 Sound pressure data are typically collected throughout the test. 测试收集了整
10、个过程有代表性的声音强度数据。Introduction to Brake Noise & Vibration 14 Repeatability and Reproducibility of Brake NVH Testing 制动NVH 测试的可重复性和再现性 The underlining mechanisms of brake squeal involve multiple aspects in the brake system. It is not uncommon to face the following problems: 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
11、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 Correlation is more difficult to achieve for low frequency squeal since more components come into play. 低频尖叫声更难完成分析，因为起作用的因素更多。 Environmental
12、factors such as weather, ambient temperature, humidity and road dust may also influence test results. 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。 Best practices to improve repeatability and reproducibility in brake NVH testing: 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
13、 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 15 Modal Test 程式测试 Provides understanding of structu
14、ral dynamic characteristics of the components and brake system. 提供对部件和制动系统的结构动力学特性的理解 Component modal test measures natural frequencies, modal damping ratios, and/or mode shapes of pad, rotor, insulator, caliper, anchor bracket, knuckle, etc. 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。 Sy
15、stem modal test is conducted on brake system on vehicle or dynamometer. 系统程式测试是制动系统导入到整车或者台架的测试。 Impact Hammer Test - quick and inexpensive. 锤击测试 迅速而且不贵。 Laser Vibrometer - more elaborate with expensive equipment. 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)
16、 measurement 操作变形振型测量Introduction to Brake Noise & Vibration 16 Brake Roughness Definition 制动粗糙度定义 Brake Roughness is the vehicle vibration, jerkiness, or pulsation that is felt by the driver and or passenger: 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 8
17、 steering wheel (shake or nibble) 方向盘( 颤抖) 8 floor boards or dash panel 底板或者仪表板 8 car 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 8 typically in the 5-60hz range 8 主要在在5-60hz 范围内 8 frequency varies with wheel speed 8 频率随着车轮转速改变 8 typi
18、cally 1 to 2 pulsations per revolution but can reach up to 10 8 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 17 Brake Roughness Definition (Contd) 制动粗糙度定义(继续) 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
19、y Sensitivity of the vehicle y 车辆敏感性 8 transmission path through suspension & steering components 8 悬挂和转向组件的传输路径 8 resonance frequency & damping of vehicle components 8 车辆组件的共振频率和阻尼 Brake Roughness, also commonly called Judder or Shudder, is often tagged with a descriptor that helps define the condi
20、tions where the roughness is noticed: 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 160 kph 高速抖动, 160 千米/ 小时Introduction to Brake Noise & Vibration 18 Judder Pad Assy Pad Assy Dust Shield Dust Shield Hub / Bearing
21、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 Rollb
22、ack 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 Tolerance
23、s Length Wheel Hub Footprint Clamp Load Lug Nut Torque Tire Imbalance Hub Flange TIR Wobble Static/ Dynamic Runout Bearing Torque Knuckle Flex Bushing Stiffness Resonances Contamination End Play Runout - Static Machining Possible Contributors to Roughness 可能引起粗糙度的因素Introduction to Brake Noise & Vibr
24、ation 19 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 20 Lining Tr
25、ansfer 衬层转移 Thermally Induced Distortions / Growth 温度导致扭曲/ 变厚 Corrosion 腐蚀 Uneven Wear Patterns from Off-Braking / On-Braking Drag 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 b
26、rake 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 varia
27、tion in the range of 50 NM. This normally is sufficient to create vehicle roughness issues. 刹车盘在1520 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Introduction to Brake Noise & Vibration 21 Mounted Runout of the rotor (bearings, ma
28、chining, lug nut forces) IDEAL = 0 刹车盘端面跳动( 轴承, 加工, 螺母受力) 理想化=0 Caliper Clearance (seal rollback, slide forces, bridge / finger stiffness) IDEAL = High 卡钳间隙( 密封反转,滑坡推力, 车桥/ 夹套的硬度) 理想化= 高 Aggressiveness of the friction material and pad dimensions IDEAL = Low 摩擦材料的侵蚀性和刹车片的尺寸 理想化= 低 Load Deformation of
29、 knuckle and caliper bracket IDEAL = 0 关节和卡钳挂钩的负荷形变 理想化=0 Factors Influencing Uneven Wear During Off-braking and On-braking Driving 影响制动结束或进行时不均匀的磨损的因素 Have to consider other brake system requirements such as pedal feel, rotor rust removal, rattle, wheel dust generation, etc. 也要考虑到其他的制动系统要求,比如踩踏板的感觉
30、, 刹车盘除锈, 卡嗒声, 轮毂灰 的产生, 等等. A recommended approach to minimize roughness is to look at the entire brake corner as an interactive system and address all these interactions instead of concentrating on only one component. 推荐一个最小化粗糙度的办法: 把整个制动部分看成一个交互式的系统, 记下所 有这些交互作用,而不是只关注一个组件。Introduction to Brake Noi
31、se & Vibration 22 Groan Definition 低沉噪音的定义 Groan is a low frequency noise that is more distinctly heard inside the vehicle than outside the vehicle: 低沉噪音是一种低频噪音，和在车外面比 ，更多的是在车内部被听到。 y Emanates from body structure in response to vibrations/pulsations created in brake y 车身结构散发的对制动造成的震动/悸动的响应 y Frequen
32、cy typically in range of 30 - 600 hz y 典型的频率范围是30 - 600 hz y Frequency content usually controlled by resonance modes in body and suspension system components y 频率通常是由人体和悬挂部件的共振模式控制的 y Frequency sometimes driven by higher order of wheel rotational speed y 频率有时是由更高的车轮转速造成的 Dynamic Groan 动态低频噪音: y Crea
33、ted during a brake stop y 一次刹车过程产生 y More pronounced from middle to end of stop y 更多产生于刹车过程的中间和结束部分 y Often requires prior thermal conditioning stops and or more aggressive stops to bring out the groan y 通常高温下刹车或强力刹车会造成低沉噪音Introduction to Brake Noise & Vibration 23 Groan Definition (contd) 低沉噪音的定义(
34、继续） Creep Groan 爬坡低沉噪音: y Created when vehicle starts inching forward under light brake pressure y 低制动压力下车辆开始向前爬行时产生 y Occurs within narrow brake pressure / speed window y 有限的制动压力下出现/ 有限的速度下出现 8 0.2 - 2 rpm 转/ 分钟 8 30 - 70 psi 磅每平方英寸 y Brake restraining the torque from automatic transmission y 刹车抑制自
35、动驾驶的扭矩 y Noise signature usually made up of a string of pulsations ( 3 - 10 per sec) y 噪音信号通常由一系列悸动组成( 每3 到10 秒) y Pulsations attributed to slip-stick event between pad/caliper assembly & rotor y 悸动是由刹车片/卡钳, 总成和刹车盘的影响下, 从静态摩擦过渡到动态摩擦的过程中产生的 End of Stop Crunch / Grunt / Release Grunt: 停车最后结束时的嘎吱声/咕哝声/
36、消除的咕哝声: y Terms to describe noise heard at end of stop as vehicle recovers from nose dive or when brake pressure released and suspension windup relaxes y 这种噪音是描述当车辆从前轮制动中恢复, 或者制动力消除并且悬挂尾部松弛时, 停车最后结束时听到 的噪音Introduction to Brake Noise & Vibration 24 Potential Contributors to Groan 低沉噪音的潜在因素 Rotor Defo
37、rmations - vane/channel surface ripples, grind/swirl surface finish patterns, etc. 刹车盘变形 叶片/ 槽的表面波动等 Pad thermal deformation 刹车片在温度变化下变形 Pad load pattern 刹车片负荷模式 Friction film on rotor, mu variation 刹车盘表面的摩擦膜, Pad physical property values, shear and compression 刹车片的物理属性值, 剪切强度和压缩比 Mu versus speed, s
38、tatic / dynamic 静态/ 动态摩擦, 速度对应的摩擦系数 Caliper stiffness 卡钳的硬度 Bushing stiffness 衬套的硬度 Etc. 等等。Introduction to Brake Noise & Vibration 25 To Reduce Roughness or Groan 降低粗糙度或低频噪音 Minimize excitation mechanism in brake 最小化制动中的激发机制 Minimize vehicle response 最小化整车的响应 y Increase Isolation / Damping in Suspe
39、nsion 增加悬挂的隔绝和阻尼 y Add Damping to body components 车身部件加入阻尼 y Shift Resonant Frequency of vehicle component 转变车辆部件的共振频率 BRAKE SYSTEM 制动系统 Torque Variation 扭矩变化 EXCITATION SUSPENSION 悬挂 Transmission 传动 VEHICLE BODY 车身 ROUGHNESS/ GROAN 粗糙度或 低频噪音 RESPONSE 激发 响应Introduction to Brake Noise & Vibration 26
40、Methods for Evaluating Roughness/Groan Issues 评测粗糙度/ 低频噪音问题的方法 Vehicle tests (subjective driver ratings, with some accelerometer, torque wheel, strain gage, and microphone signature analysis) 整车测试( 驾驶员自主测定，带着加速计，轮毂扭 矩，形变测量计和麦克风信号分析仪) y LACT 洛杉矶市交通测试 y DST 底特律郊区交通测试 y Laurel Mountain y Western ride y
41、 Eastern Mountain ride y Specialized procedures 专门的测试程序 Lab tests (quantitative comparisons, but difficult to duplicate vehicle conditions in lab setting) 实验室测试( 定量的比较，但是很难在实验室设置中完全再现整车状况) y Off-Braking / On-Braking DTV procedures 制动结束或进行时DTV程序 y Rotor / friction sample low pressure wear 低压下刹车盘和刹车片的
42、磨耗 y Dyno wear tests, bath tub 台架磨耗测试 y Static / Dynamic mu measurements 静态/ 动态摩擦系数的测量 y In-stop torque variation and rotor thickness variation measurements y 制动中力矩和刹车盘厚度变化的测试Introduction to Brake Noise & Vibration 27 Summary 总结 Brake noise and vibration issues arise from a complex interaction betwe
43、en the various brake and suspension components. 制动噪音和振动问题来自于各种制动和悬挂部件复杂的交互作用。 Successful and more robust solutions come from: 成功的和更加健全的解决方法来自： y Understanding the system and individual components 理解系统和独立的部件 y Systems approach 系统方法 y Utilization of proper tools for given problem 利用有效的工具解决问题 y Careful interpretation of test and simulation results 仔细地诠释测试和模拟结果 Need to continue progress made on enhancing lab and vehicle test procedures, data collection and analysis, as well as modeling tools. 需要不断提高实验室和整车测试的程序，数据收集和分析，还有制作工具。
