Unit 3汽车专业英语(变速器)

Unit3-1MainComponentsofEngineContentsⅠ．Pre-questionsII.TextExplanationIII.ExercisesPre-questionsPowerTrainSystem（传动系统）Thepowertrainsystem(Figure3.1)appliestothecomponentsneededtotransferthedrivefromtheenginetotheroadwheels,includingclutch,transmission,driveshaft,universaljoint,driveaxle,axleshaftandsoon.传动系统主要指汽车部件，发动机的动力传动到车轮上，包括离合器、变速器、传动轴、万向节、驱动轴、半轴等。Gearbox（变速器）ManualTransmission(MT,手动变速器)(Figure3.3)AutomaticTransmission（AT,自动变速器）(Figure3.4)PowertrainsystemClutchTransmissionManualtransmission(MT)Automatictransmission(AT)DriveshaftUniversaljointAxleshaftDifferentialFinaldrive传动系统离合器变速器手动变速器自动变速器传动轴万向节半轴差速器主减速器ShiftleverSynchronizerInputshaftOutputshaftFrontbearingRearbearingDrivegearCountershaftHousingReverseshaftReversegear换挡杆同步器输入轴输出轴前轴承后轴承传动中间轴（从动轴）壳体倒档轴倒档齿轮ContinuouslyVariableTransmissions(CVT)Acontinuouslyvariabletransmission,orCVT,isatypeofautomatictransmissionthatprovidesmoreuseablepower,betterfueleconomyandasmootherdrivingexperiencethanatraditionalautomatic.连续可变变速器，或称CVT，是能够比传统汽车变速箱提供更有效动力、更高燃油经济性、更顺畅驾驶感受的一种汽车变速箱。HistoryoftheCVTLeonardoDaVincisketchedthefirstCVTin1490.DutchautomakerDAFfirststartedusingCVTsintheircarsinthelate1950s;howevertechnologylimitationsmadeCVTsunsuitableforengineswithmorethanaround100horsepower.Inthelate80sandearly90s,SubaruofferedaCVTintheirJustymini-car,whileHondausedoneinthehigh-mileageHondaCivicHXofthelate90s.莱昂纳多.达芬奇于1490年设计出第一个CVT。在50年代末，荷兰汽车制造商达夫最早在他们的汽车中使用CVT。但受到当时技术的限制，CVT对超过100马力的发动机不适用。到了80年代末90年代初，斯巴鲁在他们的约斯帝微车中提供了CVT。而本田于90年代末，在其高里程的本田思域HX中提供了一款CVT。ImprovedCVTscapableofhandlingmorepowerfulenginesweredevelopedinthelate90sand2000s,andCVTscannowbefoundincarsfromNissan,Audi,Honda,Ford,GM,andotherautomakers.90年代末21世纪初，研究出了能够操纵更强劲发动机的改良过的CVT。现在，在日产、奥迪、本田、福特、通用和其它汽车制造商的汽车中，都可以找到CVTDrivingacarwithaCVTThecontrolsforaCVTarethesameasanautomatic:NoclutchpedalandaP-R-N-D-L-styleshiftpattern.Butwhileanautomatictransmissionhasasetnumberofgearratios(a.k.a.speeds),usually4,5or6,theCVTcanconstantlychangetherelationshipofenginespeedtocarspeed.CVT的控制机构与传统变速箱相同：两个踏板（不带离合）和一个带P-R-N-D-L档位的波箱。传统变速箱有一整套齿轮速比（用多少速来 表 关于同志近三年现实表现材料材料类招标技术评分表图表与交易pdf视力表打印pdf用图表说话 pdf 示），通常是4速，5速或6速，而CVT能够持续地改变发动机速度与汽车速度的比率。DrivingacarwithaCVTWhendrivingacarwithaCVT,youneverhearorfeelthetransmissionshift—itsimplyraisesandlowerstheenginespeedasneeded,callinguphigherenginespeeds(orRPMs)forbetteraccelerationandlowerRPMsforbetterfueleconomywhilecruising.驾驶一辆带CVT的汽车时，你不会听到或感觉到变速箱的换档－－它只是简单地按需要提高和降低发动机速度，为了得到更好的加速而提升发动机速度（或转速），在巡航时为了得到更好的燃油经济性而降低转速。Whenyoustepontheaccelerator,theengineracesasitwouldwithaslippingclutchorafailingautomatictransmission.Thisisnormal—theCVTisadjustingtheenginespeedtoprovideoptimalpowerforacceleration.·当你踩上油门时，发动机象带上空转的离合器或损坏的汽车变速箱一样转动。而这是正常的－－CVT正在调节发动机速度，以便为加速提供最佳动力。SuspensionSystem（悬架系统）SteeringarmSuspensionmemberCoilspringShockstrutStabilizershaftBalljoint转向节臂悬架横梁螺旋弹簧滑柱（减震支柱）横向稳定杆球节SteeringSystem（转向系）SteeringgearSteeringshaftSteeringwheelUniversaljointTierod转向器转向传动轴转向盘万向节转向横拉杆PowerSteeringGear（动力转向系）SteeringgearPitmanarmDraglinkSteeringknuckleAckermanarmSteeringshaftSteeringcylinderSteeringpumpSteeringtierodwheel机械转向器转向摇臂转向直拉杆转向节臂梯形臂转向轴转向油缸转向油泵转向横拉杆转向盘BrakeSystem（制动系）BrakefluidreservoirMastercylinderBrakelineVacuumpowerboosterBrakepedalHandle制动液储箱制动总泵制动管路真空助力器制动踏板拉手CaliperSlidepinDiscWheelstudBrakedrumWheelcylinder卡钳导向销盘车轮紧固螺栓制动鼓制动分泵HowCVTWorksTraditionaltransmissionsuseagearsetthatprovidesagivennumberofratios(orspeeds).Thetransmission(orthedriver)shiftsgearstoprovidethemostappropriateratioforagivensituation:Lowestgearsforstartingout,middlegearsforaccelerationandpassing,andhighergearsforfuel-efficientcruising.传统变速箱使用提供既定比率（或速度）的整套齿轮。变速箱（或传动箱）变换齿轮，对既定的情况提供最适当的比率：最低的齿轮用于起步，中间的齿轮用于加速和超车，更高的齿轮用于省油的巡航。ThoughthereareseveraltypesofCVTs,mostcarsuseapairofvariable-diameterpulleys,eachshapedlikeapairofopposingcones,withametalbeltorchainrunningbetweenthem(Fig.9-6)[1].Onepulleyisconnectedtotheengine(inputshaft),theothertothedrivewheels(outputshaft).虽然有几种CVT型号，大部分汽车都是使用一对可变径滑轮，形状象一对相向的圆锥，而且在两者之间有一条金属带或链在运转。一个滑轮连接着发动机（输入轴），另一个连接着驱动轮（输出轴）。Thehalvesofeachpulleyaremoveable;asthepulleyhalvescomeclosertogetherthebeltisforcedtoridehigheronthepulley,effectivelymakingthepulley'sdiameterlarger.每个滑轮的半部都是可移动的：当滑轮的两个半部相互移近时，传动带被推向滑轮上更高的地方，从而有效增大滑轮的直径。Changingthediameterofthepulleysvariesthetransmission'sratio(thenumberoftimestheoutputshaftrevolvesforrevolutionoftheengine),inthesamewaythata10-speedbikeroutesthechainoverlargerorsmallergearstochangetheratio.滑轮直径的变换，改变了变速箱的比率（随着时间的推移，输出轴随着发动机的转动而转动），就像十速自行车将车链放在更大或更小的齿轮上以改变比率。Makingtheinputpulleysmallerandtheoutputpulleylargergivesalowratio(alargenumberofenginerevolutionsproducingasmallnumberofoutputrevolutions)forbetterlow-speedacceleration.Asthecaraccelerates,thepulleysvarytheirdiametertolowertheenginespeedascarspeedrises.将输入滑轮变小和输出滑轮变大，可以提供低比率（发动机的大量转动带动少量输出转动）以得到更好的低速加速度。当汽车加速时，滑轮改变直径，以便在汽车速度提升时降低发动机速度。。Thisisthesamethingaconventionalautomaticormanualtransmissiondoes,butwhileaconventionaltransmissionchangestheratioinstagesbyshiftinggears,theCVTcontinuouslyvariestheratio-hencethename"continuouslyvariabletransmission".这与传统变速箱或手动变速箱的工作相同，但是传统变速箱是通过变换齿轮、按档位改变比率时，而CVT不断地改变比率－－正如其名。AdvantagesoftheCVTEnginesdonotdevelopconstantpoweratallspeeds;theyhavespecificspeedswheretorque,horsepowerandfuelefficiencyareattheirhighestlevels.Becausetherearenogearstotieagivenroadspeeddirectlytoagivenenginespeed,theCVTcanvarytheenginespeedasneededtoaccessmaximumpoweraswellasmaximumfuelefficiency.发动机并不是在所有的速度下都连续产生动力。在扭矩、马力和燃油经济性最佳的情况下，发动机有特定的速度。由于没有齿轮可以把车速直接和发动机的速度绑定，无极变速器可以通过调节发动机的速度以获取最佳的动力和最好的燃油经济性。ThisallowstheCVTtoprovidequickeraccelerationthanaconventionalautomaticormanualtransmissionwhiledeliveringsuperiorfueleconomy.这使得CVT比传统变速器或者手动变速器提交更快的加速度，同时燃油经济性也更好。DisadvantagesoftheCVTTheCVT'sbiggestproblemhasbeenuseracceptance.BecausetheCVTallowstheenginetorevatanyspeed,thenoisescomingfromunderthehoodsoundoddtoearsaccustomedtoconventionalmanualandautomatictransmissions.CVT最大的问 题 快递公司问题件快递公司问题件货款处理关于圆的周长面积重点题型关于解方程组的题及答案关于南海问题 在于用户接受性。由于CVT够能使发动机在任何速度下加速，从引擎盖下传出的声音，对于习惯了传统变速器或者手动变速器的人来说，听起来很奇怪。Flooringanautomaticcarbringsalurchandasuddenburstofpower,whereasCVTsprovideasmooth,rapidincreasetomaximumpower.Tosomedriversthismakesthecarfeelslower,whileinfactaCVTwillgenerallyout-accelerateanautomatic.自动变速器油门踩到底的时候，会使人忽然倾斜，动力忽然爆发，但是无极变速器能顺畅地、快速地加速到最大动力。对某些司机来说，这使得车速感觉较慢，但是事实上，CVT的加速速度比自动加速器要快AutomakershavegonetogreatlengthstomaketheCVTfeelmorelikeaconventionaltransmission.MostCVTsaresetuptocreepforwardwhenthedrivertakeshisorherfootoffthebrake.汽车制造商们竭尽全力使CVT感觉更像传统的变速器。大部分的CVT在司机们把脚从刹车上拿下来以后还能爬行前进。Thisprovidesasimilarfeeltoaconventionalautomatic,andservesasanindicatorthatthecarisingear.OtherCVTsoffera"manual"modethatsimulatesmanualgearchanges.这使得CVT感觉更像是传统的变速器，并且给人感觉，汽车还有变速器齿轮。有的CVT提供手动模式，模拟手动换挡。BecauseearlyautomotiveCVTswerelimitedastohowmuchhorsepowertheycouldhandle,therehasbeensomeconcernaboutthelong-termreliabilityoftheCVT.由于早期的变速器仅限于关注能应对多大马力，因此就有人质疑CVT的长期可靠性。AdvancedtechnologyhasmadetheCVTmuchmorerobust.NissanhasmorethanamillionCVTsinservicearoundtheworldandusestheminpowerfulcarssuchasthe255horsepowerMaxima,andsaystheirlong-termreliabilityiscomparabletoconventionaltransmissions.先进的技术使得CVT更加牢固。尼桑在全世界拥有一百万台无极变速器，并使用于大功率的汽车上，比如255马力的Maxima，并认为它们的长期可靠性可以和传统变速器媲美。gotogreatlengthstodosth.竭尽全力做某事Theywenttogreatlengthstokeeptheaffairsecret.He'llgotogreatlengthtogetthejobdone.serveas充当,用作,成为,起…作用Shehasservedasamodelforseveralpainters.Letthisincident serveasareminder tofuturegenerations.concernabout对...的关心；对...忧虑Heisfullof concernabout hissickmother.Thesongiveshimselfno concernabout hisfather'sillness.ProvideSheep provide uswithwool.Thehotel provides areservationofticketsforitscustomers.Continuouslyvariabletransmissionsaremoreefficientandprovidemoretorqueandpowerthantraditionaltransmissions.和传统变速器相比，无极变速器效率更高，并且能提供更大的扭矩和动力。By2012,CVTsareexpectedtohavea20percentshareoftheJapanesemarket,a4percentshareoftheNorthAmericanmarketandlessthana5percentshareoftheEuropeanmarket.到2012年为止，CVT在日本的市场份额有望达到20%，在北美的份额达到4%，在欧洲的份额应该小于5%。Whatimpressionoftheengine?complicatedpowerPre-questionsWhatarethetypesoftheengine?electricmotors,steamengines,andinternalcombustionenginesWhat’stheinternalcombustionengine?burnsfuelwithinthecylindersandconvertstheexpandingforceofthecombustionintorotaryforceusedtopropelthevehicle.Pre-questionsWords&phrasesIntakemanifold[‘mænɪfəʊld]进气管throttle [‘θrɒt(ə)l]valve[vælv]节气门Cylinder[‘sɪlɪndə]headcover气缸盖罩Distributor [dɪ‘strɪbjʊtə]分电器Cylindercover气缸盖Vent-pipe [‘ventpaip]排气管Cylinderblock气缸体Sparkplug [plʌg]火花塞timingdrivingroomcover正时传动室盖Timingbelt正时齿轮带Words&phrasesCamshaft [‘kæmʃɑːft]凸轮轴Campulley[‘pʊlɪ]凸轮带轮Crankshaft [‘kræŋkʃɑːft]曲轴Crankshafttimingbeltgearwheel曲轴正时齿形带轮Flywheel飞轮Waterjacket水套Piston['pɪst(ə)n]活塞Sump[sʌmp]油底壳Mechanism [‘mek(ə)nɪz(ə)m]机械装置，原理Connectingrod连杆lubricating [‘lu:brikeitiŋ] system润滑系统Single-cylinderenginecylinderpistonPistonpinConnectingrodcrankshaftOilpipeIntakevalveExhaustvalveTiminggearOilpumpwhatisthepowersourceofautomobileandhowtoproduce?pistonpistonpinconnectingrodcrankshaftEnginePowerisproducedbythelinearmotionofapistoninacylinder.Theconnectingrodtransmitstheup-and-downmotionofthepistontothecrankshaft,whichchangesitintorotarymotion.Pre-questionsTheenginecomprisestwomechanismandfivesystems,whatarethey?crankshaftandconnectingrodmechanism（曲轴连杆装置）,valvegear(阀动装置）,coolingsystem,lubricatingsystem,fuelsystem,startingsystem,ignitionsystemPre-questions9connectingrodflywheelcrankshaftpistonintakevalveexhaustvalvepushrodtappettiminggears■Valvegear■ConnectingrodEnginecoolingsystemEnginelubricatingsystemFuelsupplysystemValvegearpistoncrankshaftdistributorsumptiminggearcrankshaftandconnectingrodmechanismvalvegearfuelsystemSparkplugexhaustmanifoldIII.ExercisesTranslatethefollowingexpressionsintoChinese.活塞曲轴分电器油底壳正时齿轮曲柄连杆机构配气机构燃油系统火花塞排气歧管1-cylinderheadcover2-piston3-timingbelt4-waterpump5-sump6-oilpump7-crankshaft8-flywheel9-distributor10-valveIII.ExercisesReadingHowanEngineWorksTheinternalcombustionengine,asitsnameindicates,burnsfuelwithinthecylindersandconvertsexpandingforceofthecombustionintorotaryforceusedtopropelthevehicle.Theactionstakingplaceintheenginecylindercanbeclassifiedintofourstages,orstroke.“stroke”referstopistonmovement;astrokeoccurswhenthepistonmovesfromonelimitingpositiontotheother.propel[prə‘pel]v.推动，驱动limitingposition极限位置Theinternalcombustionengine,asitsnameindicates,burnsfuelwithinthecylindersandconvertstheexpandingforceofthecombustionintorotaryforceusedtopropelthevehicle.译文：内燃机，顾名思义，就是燃料在气缸内部燃烧，并且把燃烧时的膨胀力转化为驱动车辆的旋转力。II.TextExplanationConvert…..into….①转变；变换Thatbuildinghasbeenconvertedintoaschool.那座楼房改成学校了。②兑换IwanttoconvertsomeHongKongdollarsintoAmericandollars.我想把一些港元换成美元。③改变信仰、党派或意见等Shemanagedtoconverthimtoheropinion.她终于设法说服了他接受她的意见。II.TextExplanationReadingHowanEngineWorks.Theactionstakingplaceintheenginecylindercanbeclassifiedintofourstages,orstroke.发动机气缸内的工作过程可以分为四个过程或冲程。beclassifiedinto….①分类为、被分成Memorycan beclassifiedinto short-termandlong-termmemory.记忆可分为长期记忆和短期记忆。II.TextExplanationReadingHowanEngineWorks“Stroke”referstopistonmovement;astrokeoccurswhenthepistonmovesfromonelimitingpositiontotheother.“冲程”指的是活塞的运动。当活塞从一个极限位置移动到另一个极限位置，即完成了一次冲程。ReadingTheupperlimitofpistonmovementiscalledTDC(topdeadcenter).ThelowerlimitofpistonmovementiscalledBDC(bottomdeadcenter).AstrokeispistonmovementfromTDCtoBDCorfromBDCtoTDC.活塞运动的上极限位置被称为TDC（上止点）。活塞的下极限位置被称为BDC（下止点）。一个冲程是指活塞从上止点运动到下止点或者从下止点运动到上止点。ReadingInotherwords,thepistoncompletesastrokeeachtimeitchangesitsdirectionofmotion.换句话说，活塞每完成一次冲程就会改变运动方向。InotherwordsInotherwords,theyremainrelativelyconstantorstatic. 换句话说，它们相对的稳定、静止。Inotherwords,wehaveadheredtoscientificsocialism. 也就是说，我们坚持了科学社会主义ReadingWheretheentirecycleofeventsinthecylinderrequiresfourstrokes(ortwocrankshaftrevolutions),theengineiscalledafour-stroke-cycleengine.Thefourpistonstrokesareintake,compression,powerandexhaust.气缸内的全部循环运动需要四冲程（或称为二次曲轴转动），这种发动机称为四冲程循环发动机。活塞的四冲程分别为进气行程、压缩行程、做功行程和排气行程。ReadingIntakestroke.Ontheintakestroke,theintakevalvehasopened,thepistonismovingdownward,andamixtureofairandvaporizedgasolineisenteringthecylinderthroughthevalveport.Themixtureofairandvaporizedgasolineisdeliveredtothecylinderbythefuelsystemandcarburetor.Vaporized[‘veɪpəraɪzd]adj.汽化的carburetor[,kɑːbjʊ‘retə]n.汽化器ReadingOntheintakestroke,theintakevalvehasopened,thepistonismovingdownward,andamixtureofairandvaporizedgasolineisenteringthecylinderthroughthevalveport.“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。ReadingThemixtureofairandvaporizedgasolineisdeliveredtothecylinderbythefuelsystemandcarburetor.适当浓度的可燃混合气是由燃料系统和化油器提供的。Compressionstroke.AfterthepistonreachesBDC,orthelowerlimitofitstravel.Itbeginstomoveupwards.Asthishappens,theintakevalvecloses.Theexhaustvalveisalsoclosed,sothatthecylinderissealed.Asthepistonmovesupward(pushednowbytherevolvingcrankshaftandconnectingrod),theair-fuelmixtureiscompressedtoaslittleasone-tenthofitsoriginalvolume,orevenless.Whentheair-fuelmixtureiscompressed,notonlydoesthepressureinthecylindertoup,butthetemperatureofthemixturealsoincreases.revolving[rɪ‘vɒlvɪŋ]adj.旋转的volume   [‘vɒljuːm]n.量AfterthepistonreachesBDC,orthelowerlimitofitstravel.Itbeginstomoveupwards.Asthishappens,theintakevalvecloses.Theexhaustvalveisalsoclosed,sothatthecylinderissealed.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，所以这时的汽缸是封闭的。Asthepistonmovesupward(pushednowbytherevolvingcrankshaftandconnectingrod),theair-fuelmixtureiscompressedtoaslittleasone-tenthofitsoriginalvolume,orevenless.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有原体积的十分之下甚至更少。Whentheair-fuelmixtureiscompressed,notonlydoesthepressureinthecylindertoup,butthetemperatureofthemixturealsoincreases.当油气混合燃料被压缩时，不仅汽缸里的压力上升，可燃混合气的温度也随之增加了。Powerstroke.AsthepistonreachesTDConthecompressionstroke,andelectricsparkisproducedatthesparkplug.Theignitionsystemdeliversahigh-voltagesurgeofelectricitytothesparkplugtoproducethespark.Thesparkignitestheair-fuelmixture.Itnowbeginstoburnveryrapidly,andthecylinderpressureincreasedtoasmuchas3-5MPaorevenmore.Thisterrificpushagainstthepistonforcesitdownward,andapowerimpulseistransmittedthroughtheconnectingrodtothecrankpinonthecrankshaft.Thecrankshaftisrotatedasthepistonispusheddownbythepressureaboveit.AsthepistonreachesTDConthecompressionstroke,andelectricsparkisproducedatthesparkplug.Theignitionsystemdeliversahigh-voltagesurgeofelectricitytothesparkplugtoproducethespark.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。Thesparkignitestheair-fuelmixture.Itnowbeginstoburnveryrapidly,andthecylinderpressureincreasedtoasmuchas3-5MPaorevenmore.电火花点燃可燃混合气。可燃混合气开始发生剧烈燃烧，气缸内压力达到3-5兆帕，甚至更高。Thisterrificpushagainstthepistonforcesitdownward,andapowerimpulseistransmittedthroughtheconnectingrodtothecrankpinonthecrankshaft.Thecrankshaftisrotatedasthepistonispusheddownbythepressureaboveit.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。Exhauststroke.AsthepistonreachesBDCagain,theexhaustvalveopens.Now,asthepistonmovesupontheexhauststroke,itforcestheburnedgasesoutofthecylinderthroughtheexhaust-valveport.Then,whenthepistonreachesTDC,theexhaustvalveclosedandtheintakevalveopens.Now,afreshchargeofair-fuelmixturewillbedrawnintothecylinderasthepistonmovesdowntowardBDC.Thisfourstrokecycleofpistonwithinthecylinderisrepeatedtimeandagaintoputthevehicleforward.AsthepistonreachesBDCagain,theexhaustvalveopens.Now,asthepistonmovesupontheexhauststroke,itforcestheburnedgasesoutofthecylinderthroughtheexhaust-valveport.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。Then,whenthepistonreachesTDC,theexhaustvalveclosedandtheintakevalveopens.Now,afreshchargeofair-fuelmixturewillbedrawnintothecylinderasthepistonmovesdowntowardBDC.随后活塞达到上止点，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，新鲜燃混合气被吸入气缸。Thisfourstrokecycleofpistonwithinthecylinderisrepeatedagainandagaintoputthevehicleforward.上述的四个行程又继续重复，推进车辆前进。strokeBDCTDCsurgeterrificcrankpinintakestrokeCompressionstrokepowerstrokeexhauststrokefreshcharge行程，冲程；上止点；下止点；冲击，脉动；了不起的，绝妙的；曲柄销，连杆轴颈；吸气冲程；压缩冲程；做功冲程；排气冲程；吸入的新鲜混合油气I.TranslatethefollowingsentencesintoChinese.1．Engineisthepowersourceoftheautomobile.Powerisproducedbythelinearmotionofapistoninacylinder.发动机是汽车的动力源.它通过汽缸内的活塞线性运动产生的.2．Thefuelsystemworksaccordingtotherequirementsoftheengineasitprovidesanair-fuelmixturewhichmustbeinproportiontothespeedandloadplacedontheengine.燃油系统的作用是根据发动机的转速和负荷提供一定比例的可燃混合气以满足发动机的需求。III.Exercises3．Thevalvegearprovidestimelyadmissionofthefreshchargeintothecylindersandexhaustofspentgasesfromthem.配气机构机构可定时的将新鲜气体充入气缸，并且将废气排放出去。III.Exercises1．发动机主要有两大机构五大系统组成。Anengineismainlycomposedoftwomechanismsandfivesystems.2．曲柄连杆机构主要包括机体组，活塞连杆组和曲轴飞轮组。Thecrankshaftandconnectingrodmechanismmainlyconsistsoftheenginecrankcaseandcylinderblock,thepistonandconnectingrod,thecrankshaftandflywheel.III.ExercisesII.TranslatethefollowingsentencesintoEnglish.3．水泵工作时，可以将冷却液在发动机水套中和散热器之间来回流动。Whenrevolving,thewaterpumpcirculatescoolantbetweentheenginewaterjacketsandtheradiator.III.ExercisesIII.ExercisesPrincipleofFour-strokeEngine1、intakestroke2、compressstroke3、powerstroke4、exhauststrokeIntakevalveExhaustvalve