汽車專業(yè)英語(yǔ)原文及翻譯PPT學(xué)習(xí)教案

1、會(huì)計(jì)學(xué)1汽車專業(yè)英語(yǔ)原文及翻譯汽車專業(yè)英語(yǔ)原文及翻譯obtains its power by burning a liquid fuel inside the engine cylinder. There are two types ofengine: gasoline(alsocalledaspark-ignitionengine)anddiesel (alsocalledacompression-ignition engine). Both engines are called heat engines; the burning fuel generatesheat which cause

2、s the gas inside the cylinder to increase its pressure and supply power to rotatea shaft connected to the power train.發(fā)動(dòng)機(jī)作為動(dòng)力設(shè)備，常見的類型是內(nèi)燃機(jī)，其原理是通過發(fā)動(dòng)機(jī)缸內(nèi)的液體燃料燃燒而產(chǎn)生能量。發(fā)動(dòng)機(jī)可分為兩類：汽油機(jī)（點(diǎn)燃式）和柴油機(jī)（壓燃式），都屬于熱力發(fā)動(dòng)機(jī)。燃料燃燒產(chǎn)生熱量使缸內(nèi)氣體氣壓上升，從而產(chǎn)生能量，驅(qū)動(dòng)與動(dòng)力傳動(dòng)系相連接的軸旋轉(zhuǎn)。The way engine cylinders are arranged is called engine config

3、uration. In-line engines have thecylinders in a line. This design creates a simply cast engine block. In vehicle applications, thenumber of cylinders is normally from 2 up to 6. Usually, the cylinders are vertical. As the numberof the cylinders increase, the length of the block and crankshaft can be

4、come a problem. One wayto avoid this is with a V configuration. This design makes the engines block and crankshaft shorterand more rigid.發(fā)動(dòng)機(jī)的布置即發(fā)動(dòng)機(jī)氣缸的排列方式。 發(fā)動(dòng)機(jī)缸體按直線排列的即直列式，這種布置使得發(fā)動(dòng)機(jī)缸體結(jié)構(gòu)簡(jiǎn)單。汽車發(fā)動(dòng)機(jī)一般為 26 缸，通常氣缸是垂直放置的，但氣缸數(shù)量的增加會(huì)導(dǎo)致缸體和曲軸的長(zhǎng)度過大，解決問題的措施之一就是采用 V 型布置，這種布置方式可以使發(fā)動(dòng)機(jī)缸體和曲軸長(zhǎng)度尺寸更短，從而大大增加剛度。An engine lo

5、cated at the front can be mounted longitudinally and can drive either the front orthe rear wheels. Rear engine vehicles have the engine mounted behind the rear wheels. Theengine can be transverse or longitudinal and usually drives the rear wheels only.前置發(fā)動(dòng)機(jī)可以縱向布置，能夠驅(qū)動(dòng)前輪或后輪。后置發(fā)動(dòng)機(jī)布置在后輪后側(cè)，發(fā)動(dòng)機(jī)即可縱向布置又可橫向

6、布置，一般只能驅(qū)動(dòng)后輪。1.3 chassis 底盤the chassis is an assembly of those systems that are the major operating parts of a vehicle.thechassis includes the power train,steering,suspension,and braking systems.底盤由汽車的主要操作系統(tǒng)組裝而成。包括傳動(dòng)系、行駛系、轉(zhuǎn)向系和制動(dòng)系四部分。1）Powertrain system conveys the drive to the wheels.傳動(dòng)系-將驅(qū)動(dòng)力傳遞到車輪。2）

7、Steering system controls the direction of movement.轉(zhuǎn)向系-控制汽車的行駛方向。3）Suspension and wheels absorbs the road shocks.懸掛系-吸收路面震動(dòng)4）Brake slows down the vehicle.制動(dòng)系-使汽車減速緩行。1.3.1 power train system 動(dòng)力傳動(dòng)系統(tǒng)The power train transfers turning effort from the engine to the driving wheels.a power train can includ

8、e a clutch manual transmission or a torque converter for automatic transmission, a drive shaft, final drive and differential gears and driving axles. Alternatively,a transaxle may be used. A transaxle is a self-contained unit with a transmission, final drive gears and differential located in one cas

9、ing.傳動(dòng)系把發(fā)動(dòng)機(jī)輸出的扭矩傳遞給驅(qū)動(dòng)輪。傳動(dòng)系包括離合器（對(duì)應(yīng)機(jī)械變速器）或液力變矩器（對(duì)應(yīng)液力自動(dòng)變速器）、變速器、驅(qū)動(dòng)軸、主減速器、差速器和驅(qū)動(dòng)橋。另外有些傳動(dòng)系采用由變速器、主減速器和差速器組成的一體式的變速驅(qū)動(dòng)橋。（或者采用一個(gè)獨(dú)立的變速驅(qū)動(dòng)橋，即變速器在同一個(gè)箱體內(nèi)。）A vehicle with a manual transmission uses a clutch to engage and disengage the engine from thepower train. Engine torque is transmitted through the clutch to

10、 the transmission or transaxle.thetransmission contains sets of gears that increase or decrease the torque before it is transmitted第1頁(yè)/共61頁(yè)to the rest of the power train.the lower the gear ratio selected,the higher the torquetransmissioned.a vehicle starting from rest needs a lot of torque,but once

11、it is moving,it canmaintain speed with only a relatively small amount of torque.a higher gear ratio can then beselected,and engine speed is reduced.對(duì)于采用機(jī)械變速器的汽車，其發(fā)動(dòng)機(jī)扭矩由離合器傳遞給變速器或變速驅(qū)動(dòng)橋，并通過離合器來控制發(fā)動(dòng)機(jī)和傳動(dòng)系的嚙合或分離。變速器包含了不同傳動(dòng)比的齒輪副，能夠增加或減小扭矩。選擇的齒輪速比越小，傳遞的扭矩最大。汽車起步時(shí)需要較大的扭矩，一旦起動(dòng)后，僅需要較小的扭矩就可維持速度，此時(shí)應(yīng)該換用較高的檔位，以降低

12、發(fā)動(dòng)機(jī)轉(zhuǎn)速。a conventional vehicle with the engine at the front and driving wheels at the rear uses a driveshaft,called a propeller shaft,to transmit torque from transmission to the final drive.傳統(tǒng)的汽車采用前置發(fā)動(dòng)機(jī)、后輪驅(qū)動(dòng)，因此需要傳動(dòng)軸把動(dòng)力從變速器傳遞給主減速器。the final drive provides a final gear reduction to multiply the torque b

13、efore applying to thedriving axles.on front engine rear wheel drive vehicles,the final drive changes the direction ofdrive by 90 degrees. inside the final drive,a differential gear set divides the torque to the axlesand allows for the difference in speed of each wheel When cornering.axles shafts tra

14、nsmit thetorque to the driving wheels.in a rear-wheel drive vehicle,the axles can be solid or contain jointsto allow for movement of suspension.for a front-wheel drive vehicle,the drive shaft has universaljoints to allow for suspension and steering movement.主減速器的作用就是在把動(dòng)力傳遞給驅(qū)動(dòng)輪之前，降低轉(zhuǎn)速并增加扭矩。對(duì)于前置后驅(qū)的汽車，

15、主減速器還將驅(qū)動(dòng)的旋轉(zhuǎn)方向改變了 90 度。主減速器內(nèi)的差速器齒輪副，把動(dòng)力分給兩個(gè)驅(qū)動(dòng)軸，并允許兩邊車輪在轉(zhuǎn)向時(shí)具有不同的轉(zhuǎn)速。動(dòng)力最終由驅(qū)動(dòng)軸傳遞給車輪。后輪驅(qū)動(dòng)汽車的驅(qū)動(dòng)橋應(yīng)能滿足懸架的運(yùn)動(dòng)，可以是剛性的或包含運(yùn)動(dòng)副。為滿足懸架和轉(zhuǎn)向的要求，前輪驅(qū)動(dòng)汽車驅(qū)動(dòng)軸上需安裝萬向節(jié)。an automatic transmission or transaxle performs similar functions to a manual transmission ortransaxle except that gear selection is controlled either hydrauli

16、cally or electronically.theautomatic transmission uses a torque converter,which acts as a hydraulic coupling to transfer thedrive.自動(dòng)變速器或自動(dòng)變速驅(qū)動(dòng)橋的功能和機(jī)械式基本類似，區(qū)別在于檔位的選擇是液力或電力控制的。液力自動(dòng)變速器采用液力變矩（耦合）器作為連接器以傳遞動(dòng)力。1.3.2 steering system 轉(zhuǎn)向系統(tǒng)The directional motion of vehicle is controlled by a steering system. A

17、 basic steering system has 3main parts: a steering box connected to the steering wheel, the linkage connecting the steeringbox to the wheel assembly at the front wheels and front suspension parts to let the wheelassemblies pivot. When the driver turns the steering wheel, a shaft from the steering co

18、lumnturns the steering gear. The steering gear moves tie-rods that connect to the front wheels. Thetie-rods move the front wheels to turn the vehicle right or left.轉(zhuǎn)向系控制汽車行駛方向，一般由三部分組成：與轉(zhuǎn)向盤相連的轉(zhuǎn)向器、連接車輪和轉(zhuǎn)向器的傳動(dòng)結(jié)構(gòu)、允許車輪轉(zhuǎn)動(dòng)的前懸架部件。當(dāng)駕駛員轉(zhuǎn)動(dòng)方向盤時(shí)，轉(zhuǎn)向柱內(nèi)的軸帶動(dòng)轉(zhuǎn)向器運(yùn)動(dòng)，然后通過轉(zhuǎn)向傳動(dòng)機(jī)構(gòu)來轉(zhuǎn)動(dòng)車輪，從而使得汽車向左或向右行駛。1.3.3 suspension syste

19、m 懸架系統(tǒng)The purpose of the complete suspension system is to isolate the vehicle body from road shocksand vibrations, which will otherwise be transferred to the passengers and load. It must also keepthe tires in contact with the road regardless of road surface. A basic suspension system consistsof spri

20、ngs, axles, shock absorbers, arms, rods and ball joints.第2頁(yè)/共61頁(yè)整個(gè)懸架系統(tǒng)的作用是隔離來自路面的沖擊和振動(dòng)對(duì)車身的影響，防止傳遞給乘員和貨物。另外不論路面如何，懸架系統(tǒng)都應(yīng)該保持輪胎和路面接觸。懸架系統(tǒng)的基本組成包括彈性元件、車橋、減震器、桿系（臂、桿）和球副組成的導(dǎo)向機(jī)構(gòu)。the spring is the flexible component of the sussuspension.basic types are:leaf spring,coil springand torsion bars.modern passenge

21、r vehicles and can have coil springs at the front and leafsprings at the rear.heavy commercial vehicles usually use leaf springs or air suspension.彈簧是懸架的彈性元件，常見的彈簧類型有：鋼板彈簧、螺旋彈簧和扭桿彈簧。現(xiàn)代汽車大多采用小的螺旋彈簧，輕型商用車常采用的螺旋彈簧比一般乘用車的大得多，或者前懸架采用螺旋彈簧，后懸架采用鋼板彈簧。重型商用車則通常采用鋼板彈簧或空氣彈簧。wheels must be strong enough to suppo

22、rt the vehicle and withstand the forces caused by normaloperation.at the same time,they must be as light as possible to help keep unsprung weight to aminimum.車輪必須能支撐整車重量，并能承受正常工況下的載荷。同時(shí)車輪必須盡可能地輕，有助于最小化簧下質(zhì)量。wheels can be made from pressed-steeling two sections,and also be made from cast aluminiumallo

23、y.alloy wheels are popular because of their appearance and because they are lighter thansimilar steel wheels.aluminium is a better conductor of heat,so alloy wheels can dissipate heatfrom brakees and tires more effectively than steel ones.車輪可采用雙面鋼化板壓制而成，也可采用鑄造的鋁合金材料。除了外觀漂亮之外，鋁合金比鋼更輕，因此鋁合金車輪應(yīng)用較廣。另外鋁合

24、金導(dǎo)熱性更好，因此相比鋼制車輪，制動(dòng)器和車輪產(chǎn)生的熱量更容易被鋁合金車輪散發(fā)。the tire provides a cushion between the vehicle and the road to reduce the transmission of roadshocks.it also provides friction to allow the vehicle to perform its normal operations.modern tiresare manufactured from a range of materials.the rubber is mainly syn

25、thetic.two types of tireconstruction are common:cross-ply and radial.most passenger cars now use radial tires,andradials are replacing cross-ply tires on 4-wheel drives and heavy vehicles.輪胎在汽車和路面之間起緩沖作用，能減小路面沖擊。同時(shí)輪胎也提供了車輪正常行駛所需的摩擦力。輪胎是由多種材料加工而成，橡膠多是人工合成的。最常見的輪胎類型是子午線輪胎和斜交輪胎。現(xiàn)在大部分乘用車都采用子午線輪胎，在四輪驅(qū)動(dòng)和商

26、用車上，子午線輪胎也正在取代斜交胎。tube tires require an inner tube to seal air inside the tire.tubeless tires are eliminating the innertube by making the complete wheel and tire assembly airtight.a special airtight valve assembly isneeded.this can be tight fit into the rim or can be held with a nut and sealing wash

27、ers.有內(nèi)胎的輪胎用內(nèi)胎來密封內(nèi)部氣體。無內(nèi)胎的輪胎則要求車輪和輪胎具有很好的密封性，這就需要專用的密封件，可以緊固在輪緣上，也可用螺釘和密封圈來固定。1.3.4 Braking system 制動(dòng)系統(tǒng)Drum brakes have a drum attached to the wheel hub, and braking occurs by means of brakeshoes expanding against the inside of the drum. With disc brakes, a disc attached to the wheelhub is clenched b

28、etween two brake pads. on light vehicles,both of these systems are hydraulicallyoperated.the brake pedal operates a master cylinder. hydraulic lines and houses connect themaster cylinder to brake cylinders at the wheels.most modern light vehicles have either discbrakes on the front wheels and drum b

29、rakes on the rear or disc brakes on all 4 wheels.disc brakesrequire greater forces to operate them.a brake booster assist the driver by increasing the forceapplied to the master cylinder when the brake is operated.第3頁(yè)/共61頁(yè)鼓式制動(dòng)器的制動(dòng)鼓和輪轂連接，制動(dòng)蹄張開壓緊制動(dòng)鼓內(nèi)側(cè)從而產(chǎn)生制動(dòng)。在盤式制動(dòng)器上，連著輪轂的制動(dòng)盤被緊緊夾在兩個(gè)制動(dòng)塊之間。輕型汽車上都采用液壓制動(dòng)系統(tǒng)，

30、制動(dòng)踏板控制制動(dòng)主缸，通過液壓管路與車輪上的制動(dòng)輪缸相連?，F(xiàn)在輕型汽車上的制動(dòng)器，前輪采用盤式，后輪采用鼓式，或全部采用盤式。相比鼓式制動(dòng)器，盤式制動(dòng)器需要更大的作用力。在制動(dòng)時(shí)采用增壓器輔助駕駛員提高施加在主缸上的制動(dòng)力。air operated braking systems are used on heavy pressed air operating on largediameter diaphragms provides the large forces to the brake assembly that are needed.an aircompressor pumps air

31、to storage tanks.driver controlled valves then direct the compressed air todifferent wheel units to operate the friction brakes.on articulated vehicles,any delay in applyingthe trailer brake should be minimize.this is achieved by using a relay valve and a separatereservoir on the trailer.this arrang

32、ement also applies the brakes if the trailer disconnected fromthe prime mover.重型商用車多采用氣壓制動(dòng)系統(tǒng)，壓縮氣體作用在直徑較大的膜片上時(shí)能為制動(dòng)總成提供較大的制動(dòng)力。氣壓制動(dòng)系統(tǒng)靠空氣壓縮機(jī)把氣體吸入儲(chǔ)氣罐。駕駛員控制閥門開啟，使壓縮氣體進(jìn)入車輪制動(dòng)氣室進(jìn)行制動(dòng)。在鉸接車輛的拖車上采用繼動(dòng)閥和單獨(dú)的儲(chǔ)氣罐，以減小拖車制動(dòng)系統(tǒng)的時(shí)間延遲，這種布置方式還可以在拖車失去動(dòng)力時(shí)制動(dòng)拖車。all vehicles must be fitted with at least 2 independent systems.they

33、 were once called theservice brake and the emergency brake.now they are usually referred to as the foot brake and thepark brake.most light vehicles use a foot brake that operates through a hydraulic system on allwheels and a hand operated brake that acts mechanically on the rear wheels only.one comm

34、onuse of the hand brake system is to hold the vehicle when it is parked.the system are designed tobe independent So that if one fails,the otheris still available.所有汽車必須安裝至少兩套獨(dú)立的制動(dòng)系統(tǒng)，即行車制動(dòng)系統(tǒng)與緊急制動(dòng)系統(tǒng)，一般被稱之為腳制動(dòng)和停車制動(dòng)。大部分輕型汽車的腳制動(dòng)通過液壓系統(tǒng)作用在四個(gè)車輪上，而其手制動(dòng)則是機(jī)械式的，且僅作用在后輪。手制動(dòng)的一個(gè)普通用途就是停車時(shí)對(duì)汽車進(jìn)行制動(dòng)。設(shè)計(jì)兩套獨(dú)立的制動(dòng)系統(tǒng)的目的就是當(dāng)一套

35、失效時(shí)，另一套仍可工作。1.4.1 Electrical system 電器系統(tǒng)The electrical system supplies electricity for the starter, ignition, lights and heater. The electricitylevel is maintained by a charging circuit.電器系統(tǒng)為起動(dòng)機(jī)、點(diǎn)火系、照明和加熱設(shè)備提供電流，電流的大小由充電電路來維持。The charging system provides electrical energy for all of the electrical co

36、mponents on thevehicle.the main parts of the charging system include:the battery,the alternator,the voltageregulator which is usually integral to the alternator,a charging warning or indicator light andwiring that complete the circuits.the battery provides electrical components of the vehicle.it als

37、ocharges the batter to replace the energy used to start the engine.the voltage regulator preventsovercharging.充電系統(tǒng)為汽車上所有的電器系統(tǒng)提供電能。充電系統(tǒng)主要組成部分有：蓄電池、交流發(fā)電機(jī)、穩(wěn)壓器（多集成在發(fā)電機(jī)中），充電指示燈和組成電路的電線。汽車起動(dòng)時(shí)由蓄電池提供能量，一旦發(fā)動(dòng)機(jī)開始工作，交流電機(jī)為電氣設(shè)備供電，同時(shí)還對(duì)蓄電池進(jìn)行充電，以補(bǔ)償起動(dòng)所消耗的電能。穩(wěn)壓器則防止過載。1.4.2 Starting 啟動(dòng)系統(tǒng)The staring system consists of t

38、he battery,cables,starter motor,flywheel ring gear and the ignitionswitch.during starting,two actions occur.the pinion of the starter motor engages with theflywheel ring gear and the starter motor then operates to crank the engine.the starter motor is第4頁(yè)/共61頁(yè)an electrical motormounted on the engine

39、block and operated from the battery.起動(dòng)系統(tǒng)包括電池、電纜、啟動(dòng)電機(jī)、飛輪齒圈和點(diǎn)火開工。起動(dòng)需要兩個(gè)動(dòng)作，啟動(dòng)電機(jī)齒輪和飛輪齒圈嚙合，從而帶動(dòng)發(fā)動(dòng)機(jī)轉(zhuǎn)動(dòng)。起動(dòng)電機(jī)安裝在發(fā)動(dòng)機(jī)殼體上，靠電池工作。1.4.3 Ignition 點(diǎn)火系統(tǒng)A basic ignition system consists of the battery,low-tension cables,the ignition coil,distributor,coilhigh-tension cable,spark pluk cables and spark plugs.the ignitio

40、n system provides high intensesparks to spark plugs to ignite the fuel charges in the combustion chambers.the sparks must besupplied at the right time and they must have sufficient energy over a range of conditions toignite the charges.the energy comes from the battery and alternator,and voltage is

41、increased bythe ignition coil.the system has two circuits.the primary or low-tension circuit initiates thespark.the secondary or high-tension circuit produces the high voltage and distributes it to sparkplugs.點(diǎn)火系統(tǒng)包括電池、低壓電纜、點(diǎn)火線圈、分電器、高壓電纜、火花塞連線和火花塞。點(diǎn)火系統(tǒng)在火花塞處產(chǎn)生高壓火花，點(diǎn)燃發(fā)動(dòng)機(jī)燃燒室內(nèi)的燃油混合物。點(diǎn)火系統(tǒng)必須在恰當(dāng)?shù)臅r(shí)刻提供火花，并且能量

42、滿足各種工況的要求。電池和交流發(fā)電機(jī)為點(diǎn)火系統(tǒng)供電，點(diǎn)火線圈提高電壓。點(diǎn)火系統(tǒng)由兩級(jí)電路組成，初級(jí)電路（低壓電路）初始化火花，次級(jí)電路（高壓電路）產(chǎn)生高壓電，并分到各個(gè)火花塞。2.1 principle of operation 工作原理2.1.1 energy and power 能源和動(dòng)力Engine is used to produce power. The chemical energy in fuel is converted to heat by theburning of the fuel at a controlled rate. This process is called

43、combustion. If engine combustionoccurs with the power chamber. ,the engine is called internal combustion engine. If combustiontakes place outside the cylinder, the engine is called an external combustion engine.能源用于產(chǎn)生動(dòng)力。燃料以控制的速率燃燒，燃料中的化學(xué)能轉(zhuǎn)換為熱能。這個(gè)過程叫做燃燒。如果發(fā)動(dòng)機(jī)燃燒發(fā)生在動(dòng)力室內(nèi)，這種發(fā)動(dòng)機(jī)叫做內(nèi)燃機(jī)。如果燃燒發(fā)生在氣缸外，這樣的發(fā)動(dòng)機(jī)叫做外燃

44、發(fā)動(dòng)機(jī)。Engine used in automobiles are internal combustion heat engines. Heat energy released in thecombustion chamber raises the temperature of the combustion gases within the chamber. Theincrease in gas temperature causes the pressure of the gases to increase. The pressure developedwithin the combusti

45、on chamber is applied to the head of a piston to produce a usablemechanical force, which is then converted into useful mechanical power.汽車使用的發(fā)動(dòng)機(jī)是內(nèi)燃發(fā)動(dòng)機(jī)。在燃燒室內(nèi)釋放的熱能提高了室內(nèi)燃燒氣體的溫度。氣體溫度的增肌使氣體的壓力增加。在燃燒室內(nèi)產(chǎn)生的壓力作用于活塞的頂部，產(chǎn)生機(jī)械力，這個(gè)力轉(zhuǎn)換成有用的機(jī)械動(dòng)力。2.1.2 Engine TermsLinking the piston by a connecting rod to a crankshaf

46、t causes the gas to rotate the shaft through half a turn. The power stroke“uses up”the gas , so means must be provided to expel the burnt gas and recharge the cylinder with a fresh petrol-air mixture :this control of gas movement is the duty of the valves；an inlet valve allows the new mixture to ent

47、er at the right time and an exhaustvalve lets out the burnt gas afterthe gas has done its job. Engine terms are：活塞通過連桿和曲軸連接，使得氣體帶動(dòng)曲軸旋轉(zhuǎn)半圈。作功沖程耗盡了所以的氣體，這樣就必須采取相應(yīng)的措施排出廢氣以及向氣缸內(nèi)充入新鮮的可燃混合氣：氣體的運(yùn)動(dòng)由氣門來控制。進(jìn)氣閥允許新的混合氣體在適當(dāng)?shù)臅r(shí)間進(jìn)入，排氣閥在作功完成后，可以放出燃燒后的氣體。引擎術(shù)語(yǔ)：第5頁(yè)/共61頁(yè)TDC(Top Dead Center):the position of the crank and

48、piston when the piston is farther away from the crankshaft.上止點(diǎn)：活塞處于離曲軸最遠(yuǎn)處時(shí)，曲柄和活塞所處的位置。BDC(Bottom Dead Center):the position of the crank and piston when the piston is nearest to thecrankshaft.下止點(diǎn)：活塞處于離曲軸最近處時(shí)，曲柄和活塞所處的位置。Stroke : the distance between BDC and TDC; stroke is controlled by the crankshaft.

49、 行程：上止點(diǎn)和下止點(diǎn)間的距離;行程由曲軸控制。Bore : the internal diameterof the cylinder.缸徑：氣缸的內(nèi)徑Swept volume : the volume between TDC and BDC. 有效容積：上止點(diǎn)和下止點(diǎn)間的容積Engine capacity : this is the swept volume of all the cylinders.e.g. a four-cylinder enginehaving a capacity of two liters(2000cm3) has a cylinder swept volume o

50、f 500cm3.發(fā)動(dòng)機(jī)排量：所有氣缸的有效容積之和.例如一四缸發(fā)動(dòng)機(jī)有能力兩升（2000cm3）有一個(gè)氣缸排量 500cm3。Clearance volume: the volume of the space above the piston when it is at TDC.燃燒室容積：活塞處于上止點(diǎn)時(shí)，活塞上方的體積Compression ratio = (swept vol + clearance vol)(clearance vol)壓縮比：（有效容積+燃燒室容積）/燃燒室容積Two-stroke : a power stroke every revolution of the c

51、rank.兩沖程： 曲柄旋轉(zhuǎn)一圈作功一次。Four-stroke: a powerstroke every other revolution of the crank.四沖程：曲柄旋轉(zhuǎn)兩圈作功一次。2.1.3 The Four-strokeSpark-ignition Engine CycleThe spark-ignition engine is an internal-combustion engine with externally supplied in ignition ,which converts the energy contained in the fuel to kinet

52、ic energy.The cycle of operations is spread over four piston strokes. To complete the full cycle it takes tworevolutions of the crankshaft.火花點(diǎn)火式發(fā)動(dòng)機(jī)是由外部提供點(diǎn)火的內(nèi)燃機(jī)，從而將含在燃料內(nèi)的能量轉(zhuǎn)化成動(dòng)能。發(fā)動(dòng)機(jī)的一個(gè)工作循環(huán)分布在活塞的四個(gè)行程中，一個(gè)完整的工作循環(huán)曲軸需要轉(zhuǎn)動(dòng)兩圈。The downward-moving piston increases the volume in the cylinder and draws in fresh

53、air-fuelmixture through the open intakevalve.向下運(yùn)動(dòng)的活塞使氣缸里的體積增大，并且將新的空氣燃料混合物通過節(jié)氣門吸進(jìn)氣缸。The upward-moving piston reduces the volume in the cylinder and compresses the air-fuelmixture.Shortly before TDC is reached ,the spark plug ignites the compressed air-fuel mixture andthus initiates the combustion pr

54、ocess. A higher compression ratio means better utilization of thefuel. The extent of compression is restricted by the knock limit.向上運(yùn)動(dòng)的活塞使氣缸里的體積減小，從而壓縮空氣燃料混合物。在活塞即將到達(dá)上止點(diǎn)的瞬間，火花塞點(diǎn)燃?jí)嚎s的空氣燃油混合氣，從而燃燒過程開始了。壓縮比越高，燃料利用率越高，但是壓縮的程度受到爆震極限的限制。After the ignition spark at the spark plug has ignited the compressed

55、air-fuel mixture,thetemperature increases as the result of combustion of the mixture.The pressure in the cylinderincreases and forces the piston downwards. The piston transfers power to the crankshaft via theconnectingrod.當(dāng)火花塞噴出的火花點(diǎn)燃?jí)嚎s的空氣燃料混合物后，空氣燃料混合物開始然后，隨之氣缸內(nèi)的溫度開始升高。氣缸里的壓力也隨之增加，使得活塞向下運(yùn)動(dòng)。這樣活塞就把動(dòng)力通

56、過連桿傳遞給曲軸。第6頁(yè)/共61頁(yè)The upward-moving piston expels the combusted gases （exhaust gas） through the open exhaustvalve. After this 4th stroke,the cycle is repeated.向上運(yùn)動(dòng)的活塞使燃燒后的氣體（廢氣）通過排氣門排出氣缸。在這第四個(gè)行程后，整個(gè)工作工程將重復(fù)進(jìn)行。2.1.4 Engine Overall Mechanics 發(fā)動(dòng)機(jī)的總體構(gòu)造The engine has hundreds of other parts . The major par

57、ts of engine are engine block , engineheads, pistons, connecting rods, crankshaft and valves. The other parts are joined to makesystems. These systems are the fuel system, intake system, ignition system, cooling system,lubrication system and exhaust system. Each of these systems has a definite funct

58、ion. Thesesystems will be discussed in detail later。發(fā)動(dòng)機(jī)有上百個(gè)其它部件。發(fā)動(dòng)機(jī)的主要部件是發(fā)動(dòng)機(jī)缸體、發(fā)動(dòng)機(jī)頭、活塞、連桿、曲軸和閥門。其他部分也加入到系統(tǒng)中。這些的系統(tǒng)是燃油系統(tǒng)、進(jìn)氣系統(tǒng)、點(diǎn)火系統(tǒng)、冷卻系統(tǒng)、潤(rùn)滑系統(tǒng)和排氣系統(tǒng)。這些系統(tǒng)中的每一個(gè)都有一個(gè)明確的功能。這些系統(tǒng)以后將進(jìn)行詳細(xì)論述。2.2 Engine Block and Cylinder Head2.2.1 Engine BlockThe engine block is the basic frame of the engine. All other engine par

59、ts either fit inside it or fasten to it. It holds the cylinders, water jackets, and oil galleries. The engine block also holds the crankshaft, which fastens to the bottom of the block. The camshaft also fits inside the block, except on overhead-cam engines (OHC). In most cars, this block is made of

60、gray iron, or an alloy (mixture)of gray iron and other metals, such as nickel or chromium. Engine blocks are castings.氣缸體是發(fā)動(dòng)機(jī)的基本框架。發(fā)動(dòng)機(jī)的其他零件都安裝在它里面或者固定在它上。缸體里有氣缸，水套和油道。曲軸也固定在氣缸體底部。除了頂置凸輪(OHC)發(fā)動(dòng)機(jī)以外，凸輪軸都安裝在氣缸體里面。在大多數(shù)汽車?yán)?，氣缸體由灰鑄鐵或者一種灰鑄鐵和其他金屬的合金(混合物)做成，例如鎳或鉻。氣缸體是鑄件。Some engine blocks, especially those in