1、汽车考丝菜房.认多多Chapter 1 Automotive Basics在鼓式制动器上，制动鼓和轮教连接，制动蹄张开(1)Today s average car contains more than 15,000压紧制动鼓内侧从而产生制动。在盘式制动器上，separate,individual parts that must work together.连着轮教的制动盘，被紧紧夹在两个制动块之间。These parts can be grouped into four major categories:1.4Electrical systembody,engine,chassis and e
2、lectrical equipment.P1(6)The electrical system supplies electricity for the当今的车辆一般都由15000多个分散、独立且相互starter,ignition,lights and heater.The electricity level配合的零部件组成。这些零部件主要分为四类：车is maintained by a charging circuit.P8身、发动机、底盘和电气设备。电器系统为起动机、点火系、照明和加热设备提供1.1 Body电流。电流的大小由充电电路来维持。(2)The body is designed
3、to keep passengers safeAutomotive Engineering Englishand comfortable.The body styling provides anChapter 2 Internal Combustion Engineattractive,colorful,modern appearance for the vehicle.2.1.2 Engine TermsP22)Linking the piston by a connecting rod to a车身的设计要保证乘客安全舒适。车身的款式使得crankshaft causes the gas
4、to rotate the shaft through汽车看起来漂亮迷人、色彩斑斓、时尚前卫。half a turn.The power stroke uses upthe gas,so1.2 Enginemeans must be provided to expel the burnt gas and(3)The internal combustion engine is most common:recharge the cylinder with a fresh petrol-air mixture:this obtains its power by burning a liquid fu
5、el insidethis control of gas movement is the duty of the valves;the engine cylinder.There are two types of engine:(Page 10)gasoline and diesel.Both engines are called heat活塞通过连杆和轴连接，使得气体带动轴旋engines;the burning fuel generates heat which causes转半圈。作功冲程耗尽了所有的气体，这样就必须the gas inside the cylinder to incre
6、ase its pressure and采取相应的措施排出废气以及向气缸内再充入新鲜supply power to rotate a shaft connected to the的可燃混合气：气体的运动由气门来控。transmission.P32.2.1 Engine Block内燃机是最常见的，其动力来自气缸里液体燃料的1)The engine block is the basic frame of the燃烧。发动机有汽油机和柴油机两种，都称为热机engine.All other engine parts either fit inside it or燃料燃烧产生热量，使得气缸内气体压力升
7、高，从fasten to it.It holds the cylinders,water jackets,and oil而提供动力，带动连接变速器的轴旋转。galleries.The engine block also holds the crankshaft.1.3 Chassiswhich fastens to the bottom of the block.(Page 13)1.3.3Suspension缸体是发动机的基体。发动机其它的部件都安(4)The purpose of the complete suspension systemis装或固定在缸体上，包括气缸、水套和油道，以及t
8、o isolate the vehicle body from road shocks and固定在缸体底部的曲轴等。vibrations,which will otherwise be transferred to the2.2.2Cylinder Sleevespassengers and load.It must also keep the tires in2)Cylinder sleeves are used in engine blocks tocontact with the road regardless of road surface.P5provide a hard wear
9、ing material for pistons and piston整个悬架系统的作用是隔离来自路的冲击和振动对rings.The block can be made of one kind of iron that is车身的影响，防止它们传递给乘客和货物。另外不论light and easy to cast while the sleeves uses another路面如何，悬架系统都应该保持轮胎和路的接触。that is better able to stand up wear and tear.There are1.3.4 Brakingtwo main types(5)Drum
10、brakes have a drum attached to the wheelof sleeves:dry and wet(Page 10)hub,and braking occurs by means of brake shoes缸体中的气缸套为活塞和活塞环提供了一种坚expanding against the inside of the drum.With disc硬耐磨的材料。缸体可以采用某种重量轻且易铸造brakes,a disc attached to the wheel hub is clenched的铁来制造，而缸套使用的却是另一种更加耐磨损between two brake
11、pads.P6的材料成。主要有两种类型的气缸套：干缸套和湿缸套。缸壁上。2.2.3 Cylinder Head2.3.2Connecting rod3)The cylinder head fastens to the top of the block,4)The connecting rod little end is connected to thejust as a roof fits over a house.The underside formspiston pin.A.bush made from a soft metal,such asthe combustion chamber
12、with the top of the piston.bronze,is used for this joint.The lower end of theIn-line engines of light vehicles have just one cylinderconnecting rod fit the crankshaft journal.This is calledhead for all cylinders;larger in-line engines can havethe big end.(Page 19)two or more.(Page 14)连杆小头与活塞销连接，连接处有
13、像青铜这样气缸盖安装在缸体的顶部，就像安在房子上的软金属制成的衬套，连杆下端连接在曲柄轴径上，屋顶一样。缸盖的下方和活塞顶部形成燃烧室。轻称为连杆大头。型车上使用的直列发动机，所有气缸仅有一个气缸5)N.B.No.4 piston is always performing the盖，较大的直列发动机有两个或更多缸盖。companion stroke to No.1:when the inlet valve in2.2.50il PanNo.4 cylinder is fully open,No.1 cylinder inlet valve is4)The oil pump in the lub
14、ricating system drawsfully closed-this feature is useful to rememberoil from the oil pan and sends it to all working parts inwhen checking valve clearances.(Page 20)the engine.The oil drains off and runs down into the注意4号活塞和1号活塞总是成对运行：1号气pan.Thus,there is constant circulation of oil between缸进气门全闭时，4
15、号气缸进气门全开这个特点在the pan and the working pats of the engine.(Page 15)检查气门间隙时是很有用的。润滑系的机油泵从油底壳抽出机油并把机油6)As each cylinder fires,it causes the crank throw输送给发动机的所有工作部件。机油从油底壳流进to speed up.The inertia of the rest of shaft cause it to流出.因而在油底壳和发动机的工作部件之间就有stay slightly behind,resulting in a twisting action o
16、n机油定向循环流动。thecrankshaft.(Page 20)2.3.2 Piston Assembly(Page 17)当一气缸点火时，使拐的转速提高，而轴的其1)Most pistons are made from cast aluminum.The它部分由于惯性作用，有所滞后，从而导致曲轴扭piston,through the connecting rod,transfers to the转。crankshaft the force created by the burning fuel2.5:valve systemmixture.This force turns the cran
17、kshaft.大多数活塞由1.The cam is an egg-shaped piece of metal on a铝铸造而成。通过连杆的作用，活塞把可燃混合气shaft that rotates in coordination with the crankshaft.燃烧产生的力传递给曲轴，带动曲轴旋转。The metal shaft,called the camshaft,typically has1.Pistonindividual cams for each valve in the engine.As the2)In diesel engines,the combustion ch
18、amber maycamshaft rotates,the lobe,or high spot of the cam,be formed totally or in part in the piston crown,pushes against parts connected to the stem of the valve.depending on method of injection.(Page 18)This action forces the valve to move downward.This柴油机发动机根据喷油方法不同，活塞头部可action could open an inl
19、et valve for an intake stroke,or以形成全部燃烧室，也可以是燃烧室的一部分open an exhaust valve for an exhaust stroke.(p26)2.Piston Rings凸轮是一个蛋形的金属块，它安装在同曲轴协In modern engines,each piston has three rings.调运转的一根轴上，该轴称为轮轴，其上有同发动(Piston in older engines Gas Rings sometimes had four机每一个气门对应的凸轮。当轮轴旋转时，轮的rings,or even five.)The
20、 inside surface of the ring fits最高点，也就是凸圆，推动连接气门杆的部件，使in the groove on the piston.The rings outside surface得气门向下运动，在进气冲程打开进气门，在排气presses against the cylinder walls.冲程打开排气门。在新型发动机上，每个活塞有三个活塞环。（在2.In this arrangement,the cam lobes push against老式发动机上，每个活塞有四个甚至五个活塞环)round metal cylinders called cam foll
21、ower.As the lobe环的内侧装在活塞的环槽里，环的外表面紧压在气of the cam comes up under the cam follower,it pushesthe cam follower upward(away from the camshaft).during which the intake valve is also open.In otherThe cam follower rides against a push rod,whichwords,the end of the exhaust stroke and the beginningpushes agai
22、nst a rocker arm.The rocker armpivots on aof the intake stoke overlap for a short period of time.shaft through its center.As one side of the rocker armThis is called valve overlap.Valve timing and valvemoves up,the other side moves down,just like aoverlap vary on different engines.(p28)seesaw.The do
23、wnward-moving side of the rocker arm由上显而易见，排气门在进气门打开的一小段pushes on the valve stem to open the valve.时间内也打开着。换句话说，排气冲程终了和进气(p27)冲程初期有一小段时间的重叠，这称为气门重叠。在这种方案中，轮圆推动圆形的金属简，也就不同的发动机，其配气正时和气门重叠是不一样的。是挺柱。轮圆运动到挺柱下方时，推动挺柱远离6.Opening the intake valve before TDC and轮轴向上运动。挺柱带着推杆，推杆推动摇臂，摇closing it after BDC incr
24、eases the fill of air-fuel臂绕摇臂轴的中心转动。摇臂的一端升起，另一端mixture in the cylinder.Opening the intake valve early就落下，这类似于跷跷板。摇臂向下运动的一端推helps overcome the static inertia of the air-fuel mixture动气门杆打开气门。at the beginning of the intake stroke,while leaving the3.When the engine runs in compression strokeintake valv
25、e open afterand power stroke,the valves must close tightly on theirBDC takes advantage of the kinetic inertia of theseats to produce a gas-tight seal and thus prevent themoving air-fuel mixture.This increases volumetricgases escaping from the combustion chamber.If theefficiency.(p28)valves do not cl
26、ose fully the engine will not develop在上止点前打开进气门和在下止点后关闭进气full power.Also the valve heads will be liable to be门可增加气缸内可燃混气的进气量提前打开进气burnt by the passing hot gases,and there is the门有助于克服进气冲程初期可燃混气的静惯性，同likelihood of the piston crown touching an open valve,时在下止点后保持进气门打开，可充分利用可燃混which can seriously damag
27、e the engine.(p28)气运动时的惯性，这可增加容积效率。当发动机在压缩冲程和作功冲程作时，气门必7.The entire valve-train assembly can be viewed须紧贴在气门座上，形成良好的气密性以防止燃烧as a spring/mass system in which the conversion from室漏气。如果气门关闭不严，发动机就不能发挥出stored to ree energy causes forced vibration.全部的功率。而且气门头部容易被经过的高温气体Valve-train assemblies with overhea
28、d camshafts can be烧蚀，活塞顶部也可能会碰到气门使发动机严重损represented with sufficient accuracy by a 1-mass坏。system(consisting of the moving mass,the4,So that the valves can close fully somevalve-train assembly stiffness and correspondingclearance is needed in the operating mechanism.Thisdamping).(p29)means that the o
29、perating mechanism must be able to整个气门机构总成可看成一个弹簧-质量系统，move sufficiently far enough away from the valve to其储存的能量转化为自由能量时会引起受迫振动。allow the valves to be fully closed against its seat by带有项置凸轮轴的气门机构可非常精确地用单质量the valve spring.However,if the clearance is set too系统来表示，由运动质量、气门机构的刚度和相应great this will cause
30、 a light metallic tapping noise.的阻尼组成。(p28)8.Each cam must revolve once during the所以在气门传动机构中要预留一些间隙使气four-stroke cycle to open a valve.A cycle,remember,门得以完全关闭。这就是说，气门传动机构运动要corresponds with two revolutions of the crankshaft.与气门有一个充分远的距离，使得气门在气门弹簧Therefore,the camshaft must revolve at exactly half作用
31、下紧闭气门座。可是如果间隙过大，会引起轻the speed of the crankshaft.This is accomplished with傲的金属敲打声。a 2:1 gear ratio.A gear connected to the camshaft has5.It is apparent from this description that thetwice the number of teeth as a gear connected to theexhaust valve stays open for a short period of timecrankshaft.(p29)
