教学材料《汽车专业英语》-1

1AutomobileMechanics

汽车构造1.4DieselEngineOperatingFeatures

柴油发动机的工作特点1.5EngineCylinderBlockCrankcase

发动机气缸体曲轴箱1.6PistonConnectingRod

活塞连杆下一页上一页1AutomobileMechanics

汽车构造1.7CrankshaftFlywheel

曲轴飞轮1.8ValvesandValveTrain

配气机构1.9EngineFuelSystem

发动机燃油系统1.10EngineLubricatingSystem

发动机润滑系统下一页上一页1AutomobileMechanics

汽车构造1.11EngineCoolingSystem

发动机冷却系统1.12EngineIgnitionSystem

发动机点火系统1.13EngineStartingSystem

发动机启动系统1.14Clutch

离合器下一页上一页1AutomobileMechanics

汽车构造1.15Transmission

变速器1.16PropellerShaftandUniversalJoint

传动轴和万向节1.17DifferentialandRearAxles

差速器和后桥下一页上一页1AutomobileMechanics

汽车构造1.18Frame

车架1.19Tire

轮胎1.20SuspensionSystem

悬架系统1.21AutomotiveSpringsandShockAbsorbers

汽车弹性元件和减震器下一页上一页1AutomobileMechanics

汽车构造1.22SteeringSystem

转向系统1.23BrakeSystem

制动系统1.24BatteryGenerator

蓄电池发电机1.25LightsandWires

车灯与线路下一页上一页1AutomobileMechanics

汽车构造1.26OtherElectricalDevices

其他电气装置1.27Body

车身上一页1.1EngineClassificationandOverallMechanicsTheautomobileenginescanbeclassifiedaccordingto:①numberofcylinders;②arrangementofcylinders;③arrangementofvalves;④typeofcooling;⑤numberofcycles(twoorfour);⑥typeoffuelburned;⑦typeofignition.Theengineisthesourceofpowerthatmakesthewheelsgoaroundandthecarmove.¹Theautomobileengineisaninternalcombustionenginebecausethefuel(gasoline)isburnedinsideit.²Theburningofgasolineinsidetheengineproduceshighpressureintheenginecombustionchamber.³下一页返回1.1EngineClassificationandOverallMechanicsThishighpressureforcespistontomove，themovementiscarriedbyconnectingrodstotheenginecrankshaft.Thecrankshaftisthusmadetorotate:therotarymotioniscarriedthroughthepowertraintothecarwheelssothattheyrotateandthecarmoves.4Theenginerequiresafuelsystemtosupplyitwithamixtureofairandfuel.5Thefuelsystemdoesthisbypumpingliquidgasolinefromatankintothecarburetor,amixingdevicethatmixesthegasolinewithair.6Themixtureisdeliveredtotheenginewhereitisburned.7下一页返回上一页1.1EngineClassificationandOverallMechanicsTheenginealsoneedsacoolingsystem，thecombustionoftheair-fuelmixtureintheenginecreatesaveryhightemperature(ashighas2000℃to2700℃).Thecoolingsystemtakesheatawayfromtheenginebycirculatingaliquidcoolant(watermixedwithantifreeze)betweentheengineandaradiator.Thecoolantgetshotasitgoesthroughtheengine.8Itcoolsoffasitgoesthroughtheradiator.Thus，thecoolantcontinuallytakesheatawayfromtheengine，whereitcoulddodamage9anddeliversittotheradiator.Airpassingthroughtheradiatortakesheatawayfromtheradiator.10下一页返回上一页1.1EngineClassificationandOverallMechanicsTheenginealsoincludesalubricatingsystem.Thepurposeofthelubricatingsystemistosupplyallmovingpartsinsidetheenginewithlubricatingoil;theoilkeepsmovingpartsfromwearingexcessively.11Theenginerequiresafourthsystem，theignitionsystem.Theignitionsystemprovideshigh-voltageelectricsparksthatignite，orsetfireto，thechargesofair-fuelmixtureintheenginecombustionchambers.12下一页返回上一页1.1EngineClassificationandOverallMechanicsThefifthisstartingsystemanditspurposeistochangetheelectricalcurrentintothemechanicalenergytopushthecrankshaftaround.Bymeansofthis，theenginecanbestarted.Thesefivesystemsarediscussedbrieflyinfollowingsections.下一页返回上一页1.1EngineClassificationandOverallMechanicsNewWordscombustionn.燃烧chambern.室rodn.杆，连杆，活塞杆crankshaftn.机轴，曲轴rotatevi./vt.(使)旋转rotarya.(指运动的)旋转的circulatevt./vi.(使)循环coolantn.冷却剂(液态)antifreezen.防冻剂(液)，抗凝剂excessivelyad.过度地，极端地下一页返回上一页1.1EngineClassificationandOverallMechanicsvoltage.电压，伏(特)数ignitionn.点火ignitev.点燃brieflyad.简洁地，简短地PhrasesandExpressionspowertrain动力传动系统supply...with给……提供keep...from阻止下一页返回上一页1.1EngineClassificationandOverallMechanicsNotes1.Theengineisthesourceofpowerthatmakesthewheelsgoaroundandthecarmove.发动机是使车轮转动，从而驱动汽车行驶的动力来源。thatmakesthewheelsgoaroundandthecarmove为定语从句，修饰thesourceofpowermakesth.orsb.dosth.迫使某人或某物做某事，作宾语补语的不定式要省略to。例如:Hemadehissonstayathome.他要儿子待在家里。下一页返回上一页1.1EngineClassificationandOverallMechanicsThedrivermadethecrankshaftrotate.司机使曲轴转动。但是当句子变为被动语态时，不定式的to要加上。例如:Hissonwasmadetostayathome.他的儿子被迫待在家里。Thecrankshaftisthusmadetorotate.这样，使得曲轴转动。2.Theautomobileengineisaninternalcombustionenginebecausethefuel(gasoline)isburnedinsideit.下一页返回上一页1.1EngineClassificationandOverallMechanics汽车发动机是一种内燃机，因为它的燃油(汽油)是在发动机内燃烧的because引导原因状语从句。3.Theburningofgasolineinsidetheengineproduceshighpressure...汽油的燃烧在发动机的燃烧室中产生高压…动名词短语theburningofgasolineinsidetheengine在句中作主语。4.…therotarymotioniscarriedthroughthepowertraintothecarwheelssothattheyrotateandthecarmoves.下一页返回上一页1.1EngineClassificationandOverallMechanics……动力传动系统将发动机的旋转运动传给汽车车轮，从而使车轮转动，汽车行驶起来。throughthepowertrain为状语sothat引导结果状语从句。5.Theenginerequiresafuelsystemtosupplyitwithamixtureofairandfuel.发动机要求燃料供给系统为之供应汽油混合燃料。supply...with给……提供例如:Wesuppliedthemwithmoneyandclothes.我们向他们供应钱和衣服ManycountriesintheworldsuppliedAfricawithfood.世界上许多国家向非洲供应食品下一页返回上一页1.1EngineClassificationandOverallMechanics6.…amixingdevicethatmixesthegasolinewithair.……将汽油、空气进行混合的装置。amixingdevice为carburetor的同位语，that引导定语从句，在从句中作主语。7.Themixtureisdeliveredtotheenginewhereitisburned.将可燃混合气输送到发动机，并在那里进行燃烧。where关系副词，引导定语从句，在从句中做状语。8.Thecoolantgetshotasitgoesthroughtheengine.当冷却液流经发动机时，冷却液就会变热下一页返回上一页1.1EngineClassificationandOverallMechanicsas当……的时候，引导时间状语从句，文章中此句后血一句中的asitgoesthroughtheradiator也是时间状语从句。9.…whereitcoulddodamage.……热量会在发动机中造成损害。这是非限制性定语从句，说明上文。10.Airpassingthroughtheradiatortakesheatawayfromtheradiator.空气经过散热器使温度降低。passingthroughtheradiator为分词短语做定语，修饰air11.Thepurposeofthelubricatingsystemistosupplyallmovingpartsinsidetheenginewithlubricatingoil;theoilkeepsmovingpartsfromwearingexcessively.下一页返回上一页1.1EngineClassificationandOverallMechanics润滑系统的作用是向发动机内的各个运动零件提供润滑油，从而使运动零件免于过度磨损。keep...from阻止。例如:Whatshallwedotokeepthepartsfromgettingrust?我们怎样才能让这些零件不生锈?12.Theignitionsystemprovideshigh-voltageelectricsparksthatignite，orsetfireto，thechargesofair-fuelmixtureintheenginecombustionchambers.点火装置产生高压电火花，从而使发动机燃烧室中的可燃混合气燃烧。that引导定语从句，修饰sparks,下一页返回上一页1.1EngineClassificationandOverallMechanics译文发动机的分类和总体结构汽车发动机可以按这样几种情况分类:①按气缸的数量分类;②按气缸排列的方式分类;③按进气方式分类;④按冷却方式分类;⑤按工作循环的行程数分类(二行程或四行程);⑥按所用的燃料分类;⑦按点火方式分类。发动机是使车轮转动，从而驱动汽车行驶的动力来源汽车发动机是一种内燃机，因为燃油(汽油)是在发动机内燃烧的汽油的燃烧在发动机燃烧室中产生的高压力，推动活塞运动，并通过连杆传到发动机曲轴曲轴转动，动力传动系统将发动机的转动运动传给汽车车轮，从而使车轮转动，汽车行驶起来。下一页返回上一页1.1EngineClassificationandOverallMechanics发动机要求燃料供给系统为之供应汽油混合燃料〔燃料系统把汽油从油箱中抽出来，通过化油器，即一种把汽油、空气进行混合的装置，将可燃混合气输送到发动机，并在那里进行燃烧、发动机还配备有冷却系统，发动机内部的混合气燃烧会产生高温(高达2000℃—2700℃),冷却系统通过在发动机和散热器之间流动的液体冷却液(加了防冻液的水)使发动机降温当冷却液流经发动机时，冷却液就会变热，而流到散热器时又会被冷却，这样冷却液不断地将发动机中有可能造成损害的热量传递到散热器。经过散热器的空气，又将热量从散热器中带走。发动机还包括润滑系统，润滑系统的作用是向发动机内的各个运动零件提供润滑油。润滑油可使运动零件免于过度磨损。发动机的第四个系统是点火系统。点火装置产生高压电火花，从而使发动机燃烧室中的可燃混合气起燃。下一页返回上一页1.1EngineClassificationandOverallMechanics发动机的第五个系统是启动系统，启动系统的作用是把电能转变为机械能推动曲轴转动。发动机借助这种办法启动。这五个系统将在以后的章节中简要讨论。返回上一页1.2Four-stage-engineOperationTheactionstakingplaceintheenginecylindercanbedividedintofourstages，orstrokes.1“Stroke”referstopistonmovement;astrokeoccurswhenthepistonmovesfromonelimitingpositiontotheother.

2TheupperlimitofpistonmovementiscalledTDC(topdeadcenter).ThelowerlimitofpistonmovementiscalledBDC(bottomdeadcenter).AstrokeispistonmovementfromTDCtoBDCorfromBDCtoTDC.Inotherwords，thepistoncompletesastrokeeachtimeitchangesitsdirectionofmotion.3下一页返回1.2Four-stage-engineOperationWheretheentirecycleofeventsinthecylinderrequiresfourstrokes(ortwocrankshaftrevolutions)，theengineiscalledafour-stroke-cycleengine，orafour-cycleengine.Thefourpistonstrokesareintake，compression，power，andexhaust.Intakestroke.Ontheintakestroke，theintakevalvehasopened，thepistonismovingdownward，andamixtureofairandvaporizedgasolineisenteringthecylinderthroughthevalveport.Themixtureofairandvaporizedgasolineisdeliveredtothecylinderbythefuelsystemandcarburetor.下一页返回上一页1.2Four-stage-engineOperationCompressionstroke.AfterthepistonreachesBDC，orthelowerlimitofitstravel，itbeginstomoveupward.Asthishappens，theintakevalvecloses.Theexhaustvalveisalsoclosed，sothatthecylinderissealed.Asthepistonmovesupward(pushednowbytherevolvingcrankshaftandconnectingrod)，theair-fuelmixtureiscompressed.BythetimethepistonreachesTDC，themixturehasbeencompressedtoaslittleasone-tenthofitsoriginalvolume，orevenless.4Whentheair-fuelmixtureiscompressed，notonlydoesthepressureinthecylindergoup，butthetemperatureofthemixturealsoincreases.5下一页返回上一页1.2Four-stage-engineOperationPowerstroke.AsthepistonreachesTDConthecompressionstroke，anelectricsparkisproducedatthesparkplug.Theignitionsystemdeliversahigh-voltagesurgeofelectricitytothesparkplugtoproducethespark.Thesparkignites，orsetsfireto，theair-fuelmixture.Itnowbeginstoburnveryrapidly，andthecylinderpressureincreasestoasmuchas3-5MPaorevenmore.6Thisterrificpushagainstthepistonforcesitdownward，andapowerimpulseistransmittedthroughtheconnectingrodtothecrankpinonthecrankshaft.下一页返回上一页1.2Four-stage-engineOperationThecrankshaftisrotatedasthepistonispusheddownbythepressureaboveit.Exhauststroke.AsthepistonreachesBDCagain，theexhaustvalveopens.Now，asthepistonmovesupontheexhauststroke，itforcestheburnedgasesoutofthecylinderthroughtheexhaust-valveport.Then，whenthepistonreachesTDC，theexhaustvalveclosesandtheintakevalveopens.Now，afreshchargeofair-fuelmixturewillbedrawnintothecylinderasthepistonmovesdownagaintowardBDC.Theabovefourstrokesarecontinuouslyrepeated.下一页返回上一页1.2Four-stage-engineOperationNewWordsstroken.行程，冲程limitn.极限，界限upperlimit上限lowerlimit下限TDC(topdeadcenter)上止点BDC(bottomdeadcenter)下止点eventn.事件，(发动机各行程的)工作内容revolvevt./vi.(使)旋转revolutionn.旋转，转数下一页返回上一页1.2Four-stage-engineOperationvalven.气门，阀sealv.密封plugn.火花塞surgen.冲击，脉动MPa(megaPascal)兆帕(压力单位)terrifica.了不起的，绝妙的impulsen.推动力transmitv.传送crankpinn.曲柄销，连杆轴颈portn.进排气道drawv.吸(进，引，收)下一页返回上一页1.2Four-stage-engineOperationPhrasesandExpressionstakeplace发生divide...into把……分为referto涉及，有关系inotherwords换言之bythetime到……为止aslittleas少到evenless甚至更少notonly...butalso不仅……而且asmuchas多达下一页返回上一页1.2Four-stage-engineOperationevenmore甚至更多(高)freshcharge(发动机)吸入的新鲜混合油气Notes1.Theactionstakingplaceintheenginecylindercanbedividedintofourstages，orstrokes.发动机气缸内的工作过程可以分为四个阶段，或行程。takingplaceintheenginecylinder现在分词短语做定语，修饰theactions.2.“Stroke"referstopistonmovement;astrokeoccurswhenthepistonmovesfromonelimitingpositiontotheother.下一页返回上一页1.2Four-stage-engineOperation行程涉及活塞的运动;活塞从某一限定位置到另一限定位置的运动称为一个行程。whenthepistonmovesfromonelimitingpositiontotheother为时间状语从句。3.Inotherwords，thepistoncompletesastrokeeachtimeitchangesitsdirectionofmotion.换句话说，活塞每完成一个行程，就改变一次其运动的方向。eachtime在这里起连词作用，引导时间状语从句。4.BythetimethepistonreachesTDC，themixturehasbeencompressedtoaslittleasone-tenthofitsoriginalvolume，orevenless.下一页返回上一页1.2Four-stage-engineOperation当活塞到达上止点时，可燃混合气被压缩到只有原体积的十分之一，甚至更少。bythetimethepistonreachesTDC为时间状语从句。5.Whentheair-fuelmixtureiscompressed，notonlydoesthepressureinthecylindergoup，butthetemperatureofthemixturealsoincreases.当油气混合燃料被压缩时，不仅气缸里的压力上升，可燃混合气的温度也随之增加了。在这个复合句中，主句因由notonly开头，谓语使用了部分倒装，在主语之前加了助动词does。下一页返回上一页1.2Four-stage-engineOperation6.…andthecylinderpressureincreasestoasmuchas3-5MPaorevenmore.气缸内压力达到3-5兆帕，甚至更高。下一页返回上一页1.2Four-stage-engineOperation译文四行程发动机的工作过程发动机气缸内的工作过程，可以分为四个阶段，或行程。行程涉及活塞的运动;活塞从某一限定位置到另一限定位置的运动称为一行程。活塞运动的上限称为TDC(上止点)，下限称为BDC(下止点)。一个行程就是活塞从上止点到下止点，或下止点到上止点的运动。换句话说，活塞每完成一个行程，就改变一次其运动的方向。发动机气缸中的全部工作过程分为四个行程的(或者曲轴旋转两周的)，叫做四行程循环发动机，或四循环发动机。发动机的四个活塞行程是进气、压缩、做功和排气。下一页返回上一页1.2Four-stage-engineOperation进气行程:在进气行程中，进气门打开，活塞向下移动，可燃混合气通过进气门进入气缸。适当浓度可燃混合气是由燃料系统和化油器提供的。压缩行程:在活塞到达下止点时，或者是活塞下限时，活塞开始向上运动。同时，进气门关闭，排气门也关闭，所以这时的气缸是封闭的。当活塞向上运动时(这时是由转动的曲轴和连杆推动活塞)，可燃混合气被压缩。当活塞到达上止点时，可燃混合气被压缩到只有原体积的十分之一，甚至更少。当油气混合燃料被压缩时，不仅气缸里的压力上升，可燃混合气的温度也随之增加。做功行程:当活塞到达压缩行程的上止点时，火花塞产生电火花。电火花是由点火系统向火花塞提供高压电脉冲而产生的。电火花点燃可燃混合气。可燃混合气开始发生剧烈燃烧，下一页返回上一页1.2Four-stage-engineOperation气缸内压力达到3~5兆帕，甚至更高。作用于活塞上强大的推动力推动活塞向下运动，并将这一推力通过连杆传到曲轴上的连杆轴颈上。因此，当活塞受压向下运动时，推动曲轴转动。排气行程:当活塞再一次到达下止点时，排气门打开。同时，活塞向上移动，把废气经排气门排出气缸。随后活塞到达上止点，排气门关闭，进气门打开。当活塞又一次向下移动到达下止点时，新鲜可燃混合气被吸入气缸，上述的四个行程又继续重复。返回上一页1.3Two-stage-engineOperationInthefour-stroke-cycleengine，alreadydiscussedin1.2，thecompletecycleofeventsrequiresfourpistonstrokes(intake，compression，power，andexhaust).Inthetwo-stroke-cycle，ortwo-cycleengine，theintakeandcompressionstrokesandthepowerandexhauststrokesareinasensecombined.Thispermitstheenginetoproduceapowerstrokeeverytwopistonstrokes，oreverycrankshaftrotation.下一页返回1.3Two-stage-engineOperationInthetwo-cycleengine，thepistonactsasavalve，clearingvalveportsinthecylinderwallasitnearsBDC.1Afreshair-fuelchargeentersthroughtheintakeport，andtheburnedgasesexitthroughtheexhaustport.Thecompletecycleofoperationisasfollows:AsthepistonnearsTDC，ignitiontakesplace.Thehighcombustionpressuresdrivethepistondown，andthethrustthroughtheconnectingrodturnsthecrankshaft.AsthepistonnearsBDC，itpassestheintakeandexhaustportsinthecylinderwall.Burnedgases，stillundersomepressure，下一页返回上一页1.3Two-stage-engineOperationbegintostreamoutthroughtheexhaustport.Atthesametime，theintakeport，nowclearedbythepiston，beginstodeliverair-fuelmixture，underpressure，tothecylinder.2Thetopofthepistonisshapedtogivetheincomingmixtureanupwardmovement.Thishelpstosweeptheburnedgasesaheadandoutthroughtheexhaustport.AfterthepistonhaspassedthroughBDCandstartsupagain，itpassesbothports，thussealingthemoff.3Nowthefreshair-fuelcharge下一页返回上一页1.3Two-stage-engineOperationabovethepistoniscompressedandignited.Thesameseriesofeventstakesplaceagainandcontinueaslongastheengineruns.4Wementionedthattheair-fuelmixtureisdeliveredtothecylinderunderpressure.Inmostengines，thispressureisputonthemixtureinthecrankcase.Thecrankcaseissealedexceptforaleaf,orreed，valveatthebottom.Thereedvalveisaflexible，flatmetalplatethatrestssnuglyagainstthefloorofthecrankcase.Thereareholesunderthereedvalvethatconnecttotheenginecarburetor.下一页返回上一页1.3Two-stage-engineOperationWhenthepistonismovingup，apartialvacuumisproducedinthesealedcrankcase.Atmosphericpressure

liftsthereedvalveofftheholes，andair-fuelmixtureentersthecrankcase.AfterthepistonpassesTDCandstartsdownagain，pressurebeginstobuildupinthecrankcase.Thispressureclosesthereedvalvesothatfurtherdownwardmovementofthepistoncompressesthetrappedair-fuelmixtureinthecrankcase.Thepressurewhichisbuiltupontheair-fuelmixturethencausesittoflowupthroughtheintakeportintotheenginecylinderwhenthepistonmovesdownfarenoughtocleartheintakeport.5下一页返回上一页1.3Two-stage-engineOperationThetwo-strokeengineisnotonlyverysimplebutgivesnearlytwicethepowerofafourstrokeenginefromacylinderofgivensize，butitiswastefulofgasoline，assomemixtureinevitablyfindsitswayintotheexhaustsystemonthecombinesintake/exhauststroke，andtherearealwayssomecombustionproductsleftinthecylinderwhichreducetherapidburningofthefuel.6Thiskindofengineisalwaysusedinmotorcycles.下一页返回上一页1.3Two-stage-engineOperationNewWordsrequirev.需要combinev.合并，结合permitv.允许rotationn.旋转clearv.清除，开通valven.阀门nearv.接近thrustn.推进pressuren.压力streamv.流出下一页返回上一页1.3Two-stage-engineOperationdeliverv.将……发送shapev.成形sweepv.扫除sealv.密封continuev.继续mentionv.提及crankcasen.曲轴箱leafn.叶片reedn.簧片flexiblea.柔韧的，有弹性的flata.平坦的下一页返回上一页1.3Two-stage-engineOperationmetaln.金属platen.板restv.搁在，安置在snuglyad.紧贴地connectv.连接carburetorn.化油器partiala.部分的vacuumn.真空atmospherica.空气的liftv.提起下一页返回上一页1.3Two-stage-engineOperationcausev.引起trapv.诱入，使(某物)留在某处wastefula.浪费的inevitablyad.不可避免地motorcyclen.摩托车下一页返回上一页1.3Two-stage-engineOperationPhrasesandExpressionsinasense在某种意义上actas作为air-fuelcharge可燃混合油气underpressure受压，迫不得已sealoff密封exceptfor除了Leaf(reed)valve片阀givensize尺寸一定atthesametime同时findone'swayinto设法进入，挤入下一页返回上一页1.3Two-stage-engineOperationNotes1.Inthetwo-cycleengine，thepistonactsasavalve，clearingvalveportsinthecylinderwallasitnearsBDC.在二行程发动机中，活塞起到阀门的作用，当活塞接近下止点时，使气缸壁上的进排气口打开。clearingvalveports…现在分词作状语，表示伴随情况。asitnearsBDC为时间状语从句。2.Atthesametime，theintakeport，nowclearedbythepiston，beginstodeliverair-fuelmixture，underpressure，tothecylinder.下一页返回上一页1.3Two-stage-engineOperation同时，活塞使进气口露出，受压缩的可燃混合气开始进入气缸。nowclearedbythepiston过去分词作状语，为附加说明。3.AfterthepistonhaspassedthroughBDCandstartsupagain，itpassesbothports，thussealingthemoff.在活塞通过下止点，并开始上升时，活塞经过进气口和排气口，将其堵住。AfterthepistonhaspassedthroughBDCandstartsupagain为时间状语从句。thussealingthemoff现在分词作状语，表示伴随情况。下一页返回上一页1.3Two-stage-engineOperation4.Thesameseriesofeventstakeplaceagainandcontinueaslongastheengineruns.只要发动机运转，同样的动作就会反复不断地发生。aslongas只要，(=while)引导状语从句。5.Thepressurewhichisbuiltupontheair-fuelmixturethencausesittoflowupthroughtheintakeportintotheenginecylinderwhenthepistonmovesdownfarenoughtocleartheintakeport.当活塞向下运动直到露出进气口，可燃混合气所具有的压力使其上升，通过进气口进入气缸。whichisbuiltupontheair-fuelmixture定语从句，修饰thepressure.下一页返回上一页1.3Two-stage-engineOperationwhen引导时间状语从句。enough足够，常用于“形容词/副词+enough+动词不定式”中。例如:Theboyisoldenoughtoentertheschool.这孩子已到了上学的年龄。Themetalisstrongenoughtowithstandhighpressure.这种金属的强度足以承受高压。6.…assomemixtureinevitablyfindsitswayintotheexhaustsystemonthecombinesintake/exhauststroke，andtherearealwayssomecombustionproductsleftinthecylinderwhichreducetherapidburningofthefuel.下一页返回上一页1.3Two-stage-engineOperation因为在进气和排气过程中，一些可燃混合气不可避免地进入排气系统，并且总会有一些燃烧物滞留在气缸中，致使燃料不能充分燃烧。as引导原因状语从句。therearealwayssomecombustionproductsleftinthecylinder，其中left为leave的过去分词，修饰productsowhichreducetherapidburningofthefuel为定语从句，也修饰products，注意从句的谓语动词与所修饰的词在数方面要一致。下一页返回上一页1.3Two-stage-engineOperation译文二行程发动机的工作过程我们在1.2节中讲到，四行程发动机整个工作循环需要活塞完成(进气、压缩、做功、排气)四个行程。在二行程发动机中，进气和压缩行程以及做功和排气行程分别合并在一起，这使得二行程发动机每两个行程，即曲轴旋转一周，就完成一次工作循环。在二行程发动机中，活塞起到阀门的作用，当活塞接近下止点时，使气缸壁上的进排气口打开。新的可燃混合气通过进气口进入，燃烧过的废气从排气口排出。整个工作过程为:当活塞接近上止点时，发动机点火。下一页返回上一页1.3Two-stage-engineOperation燃烧产生的高压驱动活塞向下运动，通过连杆，推动曲轴转动。当活塞接近下止点时，经过气缸壁上的进排气口，燃烧过的气体，仍有剩余压力，开始从排气口喷出。同时，活塞使进气口露出，受压缩的可燃混合气开始进入气缸。活塞顶部的形状使进入气缸的可燃混合气向上运动，这样有助于扫气，引导燃烧过的废气向上运动并从排气口排出。在活塞通过下止点，并开始上升时，活塞经过进气口和排气口，将其堵住。这时活塞上方新的可燃混合气受压缩后点火。只要发动机运转，同样的动作就会反复不断地发生。我们曾提到可燃混合气是被压进气缸的。在大多数发动机中，可燃混合气是在曲轴箱中受压的。除了底部有一叶片阀(片簧阀)之外，曲轴箱是密封的。片簧阀是一片柔韧、平整的金属片。下一页返回上一页1.3Two-stage-engineOperation金属片紧贴在曲轴箱的底部。在片簧阀的下面有孔道与化油器相连。当活塞向上运行时，就会在密封的曲轴箱里产生部分真空。大气的压力将片簧阀提起，打开孔道，可燃混合气进入曲轴箱。当活塞经过上止点，又开始向下运动时，压力就开始在曲轴箱中产生。压力使片簧阀关闭，这样，活塞进一步向下运动压缩留在曲轴箱中的可燃混合气。当活塞向下运动直到露出进气口，可燃混合气所具有的压力使其上升，通过进气口进入气缸。二行程发动机不仅结构简单，而且其功率相当于具有相同气缸容积的四行程发动机的二倍。但是，在进气和排气行程中，一些可燃混合气不可避免地进入排气系统，并且总会有一些燃烧物滞留在气缸中，致使燃料不能充分燃烧。所以二行程发动机耗油较大，通常使用在摩托车上。返回上一页1.4DieselEngineOperatingFeaturesWeallknowthatdieselengines，inprinciple，workinthesamewayasgasolineenginesdo.1Bothkindsofenginesareinternalcombustionengines，buteachofthemhasitscharacteristicfeatures.2Astheirnamessuggest3thistypeofenginesburntheirfuelinsidetheworkingpartsoftheengines.Internal”means“inside，”“combustion”means“catchingfireorburning.”Inanyinternalcombustionengine，burningfuelheatsairwhichconsequentlyexpands，andinexpandingexistsapushtoapistonwhich，inturn，rotatestheenginecrankshaftthroughaconnectingrod.4下一页返回1.4DieselEngineOperatingFeaturesNowletuscomparethedieselenginewiththegasolineengine.Firstly，theexplosivemixtureofthegasolineengineisprovidedbyacarburetor，butinthecaseofthedieselenginethesupplyiseffectedbyaninjectionor"jerk"pumpwhichforcesa“shot"offuelintoeachcylinderinturnaccordingtothecorrectfiringsequence.Secondly，thefundamentaldifferencebetweengasolineanddieselenginesisthatinthegasolineenginethesourceoftheheatforignitingthecharge，namely，anelectricspark，isgeneratedoutsidetheengine，andistaken，asitwere5，下一页返回上一页1.4DieselEngineOperatingFeaturesintothewaitingchargeattherequiredinstant.Inthedieselenginethesourceofheatforignitingthechargeiscreatedwithintheenginebycompressingpureairtoadegreethatwillinitiatecombustionandtheninjectingthefuelattherighttimeinrelationtothemovementofthecrankshaft.6Bothclassesofenginesareofverysimilarconstruction.Butasthedieselengineiscalledupontowithstandverymuchgreaterstressesduetohigherpressuresincylinders，ithastobeofmoresubstantialconstruction，andisthusheavier.7Ingeneral，thedieselenginemay下一页返回上一页1.4DieselEngineOperatingFeaturesweighabout9.25kilogramsperkilowatt.Themostimportantadvantageofthegasolineengineisitslowerweightperkilowatt.Thegasolineengineforautomobilesweighsabout6.17kilogramsperkilowatt，andgasolineenginesforairplanesmayweighaslittleas0.77kilogramsperkilowatt.Thisadvantagepreventsthedieselenginefromreplacingthegasolineengineinsomeautomobilesandairplanes.8下一页返回上一页1.4DieselEngineOperatingFeaturesHowever，thedieselengineismoreefficient，becauseithashighercompressionratio.Itsratiomaybeashighas16to1.Upto40percentofthechemicalenergyoftheburningfuelmaybechangedintomechanicalenergy.Inaddition，thedieselenginerunscoolerthanthegasolineengine.Thisadvantageisespeciallyobviousatlowerspeeds.Dieseloilisnotonlycheaperthangasoline，butalsosafertostore.下一页返回上一页1.4DieselEngineOperatingFeaturesNewWordsinternala.内部的dieseln.柴油机characteristicn.特征a.特有的featuren.特点explosivea.爆炸的carburetorn.化油器effectv.完成，实现injectvt.喷射injectionn.喷油下一页返回上一页1.4DieselEngineOperatingFeaturesshotn.喷射sequencen.顺序，次序fundamentala.基本的differencen.差别sourcen.来源ignitev.点火，起燃namelyad.也就是说electrica.电的sparkn.火花vi.发出火花generatevt.产生(电，光，热)outsideprep.向外，在外下一页返回上一页1.4DieselEngineOperatingFeaturesinstantn.瞬间createvt.创造，产生purea.纯的degreen.度数，程度initiatevt.引起classn.等级，类(别)，种(类)withstandvt.经得起stressn.应力pressuren.压力，压强substantiala.坚固的，结实的weighvi.重下一页返回上一页1.4DieselEngineOperatingFeaturesreplacevt.代替kilowattn.千瓦efficienta.有效的compressionn.压缩percent百分之ration.比，比率chemicala.化学的mechanicala.机械的coola.凉的especiallyad.特别地下一页返回上一页1.4DieselEngineOperatingFeaturesobviousa.明显的cheapa.便宜的safea.安全的PhrasesandExpressionsinprinciple在原理上incaseof就...而论，关于inturn依次comparewith与...相比jerkpump脉动式喷油泵accordingto根据，按照attherequiredinstant在所需要的那一刻下一页返回上一页1.4DieselEngineOperatingFeaturesattherighttime恰在……的时候inrelationto关于，就……而论callupon要求dueto由于，起因于tobeof具有upto直至inaddition另外，此外prevent...from防止，阻止下一页返回上一页1.4DieselEngineOperatingFeaturesNotes1.Weallknowthatdieselengines，inprinciple，workinthesamewayasgasolineenginesdo.我们都知道柴油机和汽油机的工作原理是相同的。asgasolineenginesdo为定语从句。2.Bothkindsofenginesareinternalcombustionengines，buteachofthemhasitscharacteristicfeatures.这两种发动机都是内燃机，但各自具有自身的特点。3.astheirnamessuggest顾名思义。下一页返回上一页1.4DieselEngineOperatingFeatures4.Inanyinternalcombustionengine，burningfuelheatsairwhichconsequentlyexpands，andinexpandingexistsapushtoapistonwhich，inturn，rotatestheenginecrankshaftthroughaconnectingrod.在任何内燃机中，燃烧的燃料使空气受热并迅速膨胀，产生推力推动活塞，通过连杆推动发动机的曲轴。whichconsequentlyexpands为定语从句，修饰air。which,inturn,rotatestheenginecrankshaftthroughaconnectingrod为定语从句，修饰piston.下一页返回上一页1.4DieselEngineOperatingFeatures5.asitwere(=sotospeak)可以说。例如:Heis,asitwere,agrown-upbaby.他仿佛是个大孩子。6.Inthedieselenginethesourceofheatforignitingthechargeiscreatedwithintheenginebycompressingpureairtoadegreethatwillinitiatecombustionandtheninjectingthefuelattherighttimeinrelationtothemovementofthecrankshaft.在柴油发动机中，使燃油点火的热源是靠将空