汽车专业英语(幻灯片)chapter 4 braking system.ppt

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1、,Energy is required when a vehicle is accelerated from rest to a certain speed.A proportion of that energy is now stored in the vehicle and is called kinetic energy.In order to reduce the speed of the vehicle,the brakes have to convert the kinetic energy to heat energy;the speed of conversion govern

2、s the rate at which the vehicle slows down.,汽车从原地起步加速到某一速度需要能量。储存在汽车中的那部分能量称为动能。要降低车速,制动器必须把汽车的动能转换为热能；转换的速度决定了汽车减速的快慢。,Review 1:Whats the main function of braking system?,1.disc brake 2.brake caliper 3.brake hose 4.brake pedal 5.master cylinder 6.wheel cylinder 7.drum brake,Review 2:List the main p

3、arts of braking system.,Review 2:List the main parts of braking system.,1、Energy-supplying device 供能装置2、Control device 控制装置3、Transmission device 传能装置4、Brake 制动器,Metering Valve 节压阀Proportioning Valve 比例阀 Check Valve 单向阀Solenoid Valve 电磁阀Combination Valve 组合阀Delay Valve 延迟阀Modulator Valve 调节阀,Accordin

4、g to function According to the types of energy used,Review 3:Which types do the braking system have?,service braking systemparking braking systemadditional retarding braking systemsecondary(emergency)braking system,muscular energy braking system(non-power braking system)energy assisted braking syste

5、m(power assisted braking system)non-muscular energy braking system(power braking system)inertial braking systemgravity braking system,The three types of braking systems are in use today:service braking system,parking braking system and additional retarding-braking system.The service braking system a

6、nd the parking braking system have separate control and transmission devices.The service braking system is normally foot-operated,while the parking braking system is hand-operated.目前使用的制动系统有三种类型：行车制动系，住车制动系和辅助制动系行车制动系和住车制动系有独立的控制和传动装置行车制动系通常使用脚刹，而驻车制动系通常使用手刹,According to energy transmission Accordin

7、g to circuit,Review 3:Which types do the braking system have?,single-circuit braking systemmulti-circuit braking system,mechanical braking system hydraulic braking system pneumatic braking systemelectromagnetic braking systemcombination braking system,Two types of brakes are used in modern cars:drum

8、 brakes and disc brakes.Since 1976,all cars have used disc brakes on the front wheels.Most cars use drum brakes on the rear wheels.In both drum and disc brakes,a hydraulic system applies the brakes.The hydraulic system connects the brake pedal to the brake parts at each wheel.目前使用的制动器有两种类型：鼓式制动器和盘式制

9、动器从1976年开始，所有的汽车前轮都使用盘式制动器,大部分汽车后轮使用的是鼓式制动器.在盘式制动器和鼓式制动器中都使用液压系统.液压系统把制动踏板与每个车轮的制动部件相连接.,Review:Types of the brake,Drum brake 鼓式制动器,Disc brake盘式制动器,Wheel cylinder brakeCam actuated brakeWedge actuated brake,Disc brake with fixed caliperDisc brake with floating caliper,Review:Types of the brake,制动主缸,

10、制动轮缸,制动鼓,支承销,Master cylinder,Wheel cylinder,Brake shoe and lining制动蹄和制动衬片,Brake drum,Anchor pin,return spring,Brake shoe and lining,Brake drum,These have two shoes,anchored to a stationary back-plate,which are internally expanded to contact the drum by hydraulic cylinders or a mechanical linkage.,这种

11、制动器有两个固定在制动底板上的制动蹄，通过液压轮缸或机械杆系作用从内侧向外推开与制动鼓接触。,Review:Operation process of drum brake,Review:Operation process of drum brake,Review:Whats main types of Drum brakes.,Simplex drum brake(Leading trailing shoe brake)领从蹄式制动器Duo-trailing shoe brake(Two trailing shoe brake)双从蹄式制动器Double leading shoe brake

12、单向双领蹄Duo-duplex drum brake（Dou two leading shoe brake）双向双领蹄式制动器Uni-servo drum brake 单向自增力式制动器Duo-servo drum brake 双向自增力式制动器,Simplex drum brake 领从蹄式制动器,trailing shoe,Leading shoe,In the case of the simplex brake,C*(brake factor)is the sum of the values for the individual shoes,and is 2.0（referred to

13、a specific coefficient of friction)A disadvantage of this design is the great difference in the braking effect between the two brake shoes,and the resulting greatly increased wear on the leading shoe.For this reason,the trailing shoe is often equipped with a much thinner lining than the leading shoe

14、.,就领从蹄而言，C*表示各蹄的值的总数，且.(特指某一摩擦系数）这种设计的缺点是两个制动蹄制动效果有很大不同，结果大大增加了领蹄上的摩擦因此，从蹄的摩擦衬片比领蹄薄,+plus加号；正号-minus减号；负号plus or minus正负号is multiplied by乘号is divided by除号is equal to等于号is not equal to不等于号is equivalent to全等于号is equal to or approximately equal to等于或约等于号is approximately equal to约等于号is less than小于号is mo

15、re than大于号is not less than不小于号is not more than不大于号is less than or equal to小于或等于号is more than or equal to大于或等于号%per cent百分之,英文标点符号翻译,.full stop句号,comma逗号:colon冒号;semicolon分号?question mark问号!exclamation mark(英式英语)exclamation point(美式英语)apostrophe撇号-hyphen连字号-dash 破折号.dots/ellipsis省略号single quotation m

16、arks 单引号double quotation marks 双引号 parallel 双线号 division 分节号arrow 箭号；参见号,Celsius system摄氏度open brace,open curly左花括号close brace,close curly右花括号(open parenthesis,open paren左圆括号)close parenthesis,close paren右圆括号()brakets/parentheses括号open bracket 左方括号close bracket 右方括号 square brackets方括号.period,dot句号，点

17、|vertical bar,vertical virgule竖线&ersand,and,reference,ref和，引用*asterisk,multiply,star,pointer星号，乘号，星，指针/slash,divide,oblique 斜线，斜杠，除号/slash-slash,comment 双斜线，注释符#pound井号backslash,sometimes escape反斜线转义符，有时表示转义符或续行符tilde波浪符,per mill千分之infinity无限大号varies as与成比例(square)root平方根since;because因为hence所以equ

18、als,as(proportion)等于，成比例angle角semicircle半圆circle圆circumference圆周,pi 圆周率triangle三角形perpendicular to垂直于union of并，合集intersection of 交，通集the integral of 的积分(sigma)summation of总和degree度minute分second秒,Dou-duplex drum brake,An advantage of this type of brake is the nearly equal brake lining wear on both sh

19、oes and the higher internal transmission ratio in comparison to simplex brakes.With two leading shoes,brake factors of C3.0 are achieved,however,these figures cannot be held constant throughout a long period of braking due to the susceptibility to fading of this type of brake.,这种制动器的优点是两个蹄上制动衬片磨损几乎相

20、同，与领从蹄制动器相比它的内传动比较高使用两个领蹄，制动因素可以达到3.0，但是由于这类制动器制动性能易于衰退而使这个值不能在长距离制动时保持恒定,Duo-servo drum brake,凸轮式制动器工作过程,This type of drum brake has an application mechanism which is simpler,more reliable and insensitive to temperature.It comprises diaphragm cylinder,automatic slack adjuster,brake shaft and S-cam.

21、,这类凸轮制动器有一套简单，稳定，恒温机构它包括膜片弹簧制动器室，自动调整臂，制动轴和S凸轮.,制动钳体caliper,活 塞piston,制动块Friction pad,制动盘disc,Disc brake with fixed caliper,Disc brake with floating caliper,Exposed to the air,disc brakes radiate the heat to the air better than drum brakes:This means that the brake can be operated continuously for a

22、 longer period,i.e.they have a greater resistance to fade(fall-off in brake efficiency due to heat).,由于暴露于空气中，盘式制动器的散热效果比鼓式的要好：这意味着盘式制动器能持续使用更长的时间，也就是说其抗热衰退性（因受热导致制动效能下降）要好得多。,Disc brakes as used in most passenger cars are slowly beginning to be used in commercial vehicles as well.Aside from their u

23、se in fast coaches,current use of disc brakes in commercial vehicles is primarily limited to front-axle brakes for commercial vehicles up to a weight of approx.7.5 t which are driven in a manner similar to passenger cars.常用在许多乘用车上的盘式制动器正逐渐被用于商用车.它们除用于快速客车外,目前盘式制动器在商用车上的用途基本限制在前轴制动,因为商用车重量约等于7.5吨时驱动方

24、式与乘用车相似.,An advantage of disc brakes in comparison to drum brakes:Better gradual braking efficiencyEqual wear of the inboard and outboard brake pads Brake noise is better suppressed Relatively constant brake factor performance with lower susceptibility to fadingDisadvantage：Short brake pad life when

25、 used on heavy-duty commercial vehiclesHigher acquisition and operating costs,The master cylinder contains two separate sections,there is a piston in each section and both pistons are connected to a brake pedal in the drivers compartment.,制动主缸由两个分开的部分组成，每个部分都有一个活塞，两个活塞都与驾驶室里的制动踏板相连接。,Review:Operatio

26、n process of non-power brakes,When the brake pedal is pushed by the driver,the two pistons move in the two sections of the master cylinder.This forces brake fluid out and through the brake lines,or tubes,to the brake mechanisms at the wheels.In a typical system,the brake fluid from one section of th

27、e master cylinder goes to the two front-wheel brakes.The brake fluid from the other section goes to the two rear-wheel brakes.The purpose of this that,if one section fails,the other section will still provide braking.当驾驶员踩下制动踏板时，主缸两套管路中的两活塞移动迫使制动液流出经过制动管路进入各车轮的制动装置中在标准制动系统中，主缸的一条管路中的制动液流向两个前轮制动装置中，另

28、一条管路的制动液流向两个后轮制动装置其目的是，如果其中一套管路失灵，另一条管路仍然能够提供制动,制动踏板Brake pedal,真空助力器Vacuum booster,储液室Brake-fluid reservoir,盘式制动器Disk brake,制动主缸Master cylinder,比例阀Proportioning valve,真空管Vacuum connection,鼓式制动器Drum brake,Power-assisted brakes,The operating principle of the power-assisted system is the same as for a

29、 non-power system.However,braking force is increased through the use of a vacuum booster unit.Atmospheric pressure helps to push the brake pedal.Thus,less muscle effort is required.,伺服制动系的工作原理与人力制动系相同。然而，伺服制动系通过采用真空助力装置来增加制动力。大气压力有助于踩下制动踏板。这样，制动时几乎不需要人力。,In SI engines,vacuum is generated via a conne

30、ction to the engine intake manifold,and diesel engines use a vacuum pump.火花点火式发动机通过连接发动机的进气支管产生真空，而柴油发动机使用真空泵,The vacuum booster is a pedal-force booster which is combined with a tandem master cylinder.The boost factor i can be varied in design by an appropriate choice of lever control.Via the lever

31、 control,a proportional assisting force is superimposed on the pedal force,and both act together on the tandem master cylinder.At the same time,a reactive force is conveyed to the driver,which enables him to meter the braking action correctly.真空助力器是一个与制动主缸串联在一起的踏板助力器设计时助力因数i可通过选择适当的杠杆控制而不同通过杠杆控制，一定比

32、例的助力叠加在踏板力上并同时对串联式制动主缸作用同时，反作用力传给驾驶员，使他能正确的估计制动行为,Tandem master cylinder,储液室fluid reservoir,补偿孔Snifter hole,Rear brake,Front brake,中间活塞Intermediate piston,机架housing,推杆Push-rod,Operation principle(Tandem master cylinder):after passing over snifter hole,the push-rod piston forces the brake fluid into

33、brake circuit.The compression of the spring and the pressure buildup in brake circuit I actuates the intermediate piston,which passes over snifter hole and builds up pressure in brake circuit.工作原理(串联式制动主缸）：推杆活塞经过补偿孔迫使制动液流入制动回路弹簧压缩力及制动回路上的压力促动中间活塞，使它经过补偿孔并在制动回路上产生压力,The port for brake circuit I,which

34、 supplies the rear drum brakes,has a pre-pressure valve which assures a residual pressure of approx 150kPa when the brakes are released.This prevents the entry of air through the wheel-cylinder seals.制动回路I上的孔为后轮鼓式制动器提供制动液其内有一个预压阀，它保证制动踏板释放时有150kPa残余压力,阻止空气通过轮缸密封处进入,The more heavily the driver brakes

35、,the greater is the dynamic shifting of weight from the rear axle to the front axle.With the vehicle empty,the braking force at the rear axle may be so great that the rear axle locks before the front axle.This can lead to instability when braking,i.e.to skidding.Braking stability is obtained when,ir

36、respective of vehicle loading,the front axle always locks before the rear axle.The correct braking-force distribution can be achieved by brakepressure-regulating valves which are installed in the brake lines to the wheels of the rear axle.驾驶员制动力越大，从后轴到前轴的转移的重量越大汽车空载时，后轴上制动力很大以至后轴在前轴之前抱死这导致制动不稳定，即发生滑

37、动当前轴总在后轴之前抱死时可获得制动稳定性，它与汽车载重无关通过安装在连接后轮的制动管路上的制动压力调节装置可以得到正确的制动力分配,During initial braking,the control spring keeps the valve seat at the stepped piston open until the brake pressure has reached a level which,according to the active area of the stepped piston,corresponds to the force of the control s

38、pring.开始制动时，控制弹簧使阶梯型活塞上的阀门座打开，直到制动压力按照阶梯形活塞有效面积达到与控制弹簧力相同的程度,Review 7:Which components do compressed air brakes have?,1、Energy-supplying device 供能装置 2、Control device 控制装置 3、executive device 执行装置,1 Compressor 空气压缩机 2 brake cylinder 制动气室3 brake valve 制动阀 4 water-drain valve 放水阀5 air reservoir 湿储气罐 6 m

39、aster reservoir 主储气罐 7 pressure regulator 调压阀 8 barometer 气压表9 bugle 喇叭,A compressor is used as the energy source,and is usually of the plunger type;the intake air is compressed via automatic suction and delivery valves.空压机用做能源一般是活塞型的通过自动进气阀进入的空气在其内被压缩,Service brake valve,The combination brake cylin

40、der consists of a single-chamber diaphragm cylinder for the service brakes and a spring-brake actuator for the parking brakes.The cylinder and spring brake actuator are in tandem and act on a common pressure rod.复合式制动室由行车制动器的单室膜片弹簧制动气室和驻车制动器弹簧助力装置组成制动气室和弹簧助力装置串联在一起并对压力杆作用,Electrohydraulic braking sy

41、stems are designed to allow electonic control of vehicle braking while retaining a reduced hydraulic system.The EHB control unit receives inputs from sensors connected to the brake pedal.In normal operation,a backup valve is closed and the controller activates the brakes of the wheel through an elec

42、tric motor driven hydraulic pump.When the controller goes into a fail-safe mode,the backup valve is opened,which allows the brakes to be controlled through a conventional hydraulic circuit.电液制动系统允许电子控制汽车制动,同时保留了简化的液压系统.电液制动系统控制单元接受与制动踏板连接的传感器的输入.正常工作时,后备阀关闭,控制器通过由液压泵驱动的电动机起动制动器.当控制器进入失效安全模式时,后备阀打开,并

43、允许传统的液压回路控制制动器.,Additional retarder brake system辅助制动系,a.Exhaust retarder 排气缓速器b.Hydrodynamic retarder 液力缓速器c.Electromagnetic retarder电磁缓速器d.Traction motor retarder牵引电机缓速器e.Aerodynamic retarder空气动力缓速器,In order to brake the vehicle,the field coils are supplied with current(from the battery or alternat

44、or)and generate a magnetic field.Eddy currents are induced in the rotors as they pass through this field.This generates a braking torque whose magnitude is a function of the excitation of the stator coils.为了刹车，用电池或发电机给励磁线圈供电从而产生磁场当转子经过磁场时感应生成电涡流这样产生的制动力矩的大小是定子线圈中励磁电流的函数,Brake slip=(F R)/F 100%滑动率；10

45、0BBraking-force coefficient 制动力系数SLateral-force coefficient 侧向力系数,B,s,main parts of ABS（antilock braking system),Wheel cylinder,Wheel-speed sensor,Electronic controller,solenoid-valve,coil,motor,hydraulic pump,plunger,The wheel-speed sensor monitors the motion of the wheel.If one wheel shows signs o

46、f locking,there is a sharp rise in peripheral wheel deceleration and in wheel slip.If these exceed defined critical values,the controller sends commands to the solenoid-valve unit to stop or reduce the buildup of wheel-brake pressure until the danger of lock-up has passed.The brake pressure must the

47、n be built up again in order to ensure that the wheel is not under-braked.轮速传感器监控着车轮的运动，如果一个车轮出现抱死信号，也就是车轮减速度急剧增大且车轮滑动率也增加如果超出临界值，控制器给电磁阀发送命令来停止或降低制动压力，直到抱死的危险消除然后制动力再增大确保车轮制动力不会不足,A wheel-speed sensor consists of a toothed pulse ring and an inductive wheel-speed pickup.The pulse ring is mounted on

48、the hub and,as the rotates,produces in the wheel-speed pickup an A.C.voltage,the frequency of which is proportional to the wheel speed.轮速传感器由运动的齿圈和磁感应传感头构成齿圈安装在轮毂上，车轮转动时，在传感头上产生频率与车速成正比的交流电压,alternating current,A.C.,From the signals from the wheel-speed pickups,these microcomputers calculate the whe

49、el speeds as well as the wheel decelerations and accelerations.A vehicle reference speed is formed from the wheel speeds of two diagonally opposite wheels.With this reference speed and the individual wheel speeds it is possible to calculate the brake slip for each wheel.If a wheel has a tendency to lock,this is determined from the wheel-acceleration and slip signals.通过来自传感头的信号，微机不仅计算出车速而且还计算出减速度和加速度参考车速由两对角线位置车轮的轮速构成用这个参考速度和单胎速度可以计算出每个车轮的滑动率车轮是否有抱死趋势决定于车轮的加速度和滑动信号,ABS系统的工作原理,常规制动（升压）过程,轮缸减压过程,轮缸保压过程,轮缸增压过程,