Unit 3汽車專業(yè)英語(yǔ)(變速器)

Unit3-1

MainComponentsofEngine

ContentsⅠ．Pre-questionsII.Text

ExplanationIII.ExercisesPre-questionsPowerTrainSystem（傳動(dòng)系統(tǒng)）Thepowertrainsystem(Figure3.1)appliestothecomponentsneededtotransferthedrivefromtheenginetotheroadwheels,includingclutch,transmission,driveshaft,universaljoint,driveaxle,axleshaftandsoon.

傳動(dòng)系統(tǒng)主要指汽車部件，發(fā)動(dòng)機(jī)的動(dòng)力傳動(dòng)到車輪上，包括離合器、變速器、傳動(dòng)軸、萬(wàn)向節(jié)、驅(qū)動(dòng)軸、半軸等。Gearbox（變速器）

ManualTransmission(MT,手動(dòng)變速器)(Figure3.3)

AutomaticTransmission（AT,自動(dòng)變速器）(Figure3.4)PowertrainsystemClutchTransmissionManualtransmission(MT)Automatictransmission(AT)DriveshaftUniversaljointAxleshaftDifferentialFinaldrive傳動(dòng)系統(tǒng)離合器變速器手動(dòng)變速器自動(dòng)變速器傳動(dòng)軸萬(wàn)向節(jié)半軸差速器主減速器ShiftleverSynchronizerInputshaftOutputshaftFrontbearingRearbearingDrivegearCountershaftHousingReverseshaftReversegear換擋桿同步器輸入軸輸出軸前軸承后軸承傳動(dòng)中間軸（從動(dòng)軸）殼體倒檔軸倒檔齒輪ContinuouslyVariableTransmissions(CVT)Acontinuouslyvariabletransmission,orCVT,isatypeofautomatictransmissionthatprovidesmoreuseablepower,betterfueleconomyandasmootherdrivingexperiencethanatraditionalautomatic.連續(xù)可變變速器，或稱CVT，是能夠比傳統(tǒng)汽車變速箱提供更有效動(dòng)力、更高燃油經(jīng)濟(jì)性、更順暢駕駛感受的一種汽車變速箱。HistoryoftheCVTLeonardoDaVincisketchedthefirstCVTin1490.DutchautomakerDAFfirststartedusingCVTsintheircarsinthelate1950s;howevertechnologylimitationsmadeCVTsunsuitableforengineswithmorethanaround100horsepower.Inthelate80sandearly90s,SubaruofferedaCVTintheirJustymini-car,whileHondausedoneinthehigh-mileageHondaCivicHXofthelate90s.萊昂納多.達(dá)芬奇于1490年設(shè)計(jì)出第一個(gè)CVT。在50年代末，荷蘭汽車制造商達(dá)夫最早在他們的汽車中使用CVT。但受到當(dāng)時(shí)技術(shù)的限制，CVT對(duì)超過(guò)100馬力的發(fā)動(dòng)機(jī)不適用。到了80年代末90年代初，斯巴魯在他們的約斯帝微車中提供了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世紀(jì)初，研究出了能夠操縱更強(qiáng)勁發(fā)動(dòng)機(jī)的改良過(guò)的CVT?，F(xiàn)在，在日產(chǎn)、奧迪、本田、福特、通用和其它汽車制造商的汽車中，都可以找到CVTDrivingacarwithaCVTThecontrolsforaCVTarethesameasanautomatic:NoclutchpedalandaP-R-N-D-L-styleshiftpattern.Butwhileanautomatictransmissionhasasetnumberofgearratios(a.k.a.speeds),usually4,5or6,theCVTcanconstantlychangetherelationshipofenginespeedtocarspeed.CVT的控制機(jī)構(gòu)與傳統(tǒng)變速箱相同：兩個(gè)踏板（不帶離合）和一個(gè)帶P-R-N-D-L檔位的波箱。傳統(tǒng)變速箱有一整套齒輪速比（用多少速來(lái)表示），通常是4速，5速或6速，而CVT能夠持續(xù)地改變發(fā)動(dòng)機(jī)速度與汽車速度的比率。DrivingacarwithaCVTWhendrivingacarwithaCVT,youneverhearorfeelthetransmissionshift—itsimplyraisesandlowerstheenginespeedasneeded,callinguphigherenginespeeds(orRPMs)forbetteraccelerationandlowerRPMsforbetterfueleconomywhilecruising.駕駛一輛帶CVT的汽車時(shí)，你不會(huì)聽(tīng)到或感覺(jué)到變速箱的換檔－－它只是簡(jiǎn)單地按需要提高和降低發(fā)動(dòng)機(jī)速度，為了得到更好的加速而提升發(fā)動(dòng)機(jī)速度（或轉(zhuǎn)速），在巡航時(shí)為了得到更好的燃油經(jīng)濟(jì)性而降低轉(zhuǎn)速。Whenyoustepontheaccelerator,theengineracesasitwouldwithaslippingclutchorafailingautomatictransmission.Thisisnormal—theCVTisadjustingtheenginespeedtoprovideoptimalpowerforacceleration.·當(dāng)你踩上油門時(shí)，發(fā)動(dòng)機(jī)象帶上空轉(zhuǎn)的離合器或損壞的汽車變速箱一樣轉(zhuǎn)動(dòng)。而這是正常的－－CVT正在調(diào)節(jié)發(fā)動(dòng)機(jī)速度，以便為加速提供最佳動(dòng)力。SuspensionSystem（懸架系統(tǒng)）SteeringarmSuspensionmemberCoilspringShockstrutStabilizershaftBalljoint轉(zhuǎn)向節(jié)臂懸架橫梁螺旋彈簧滑柱（減震支柱）橫向穩(wěn)定桿球節(jié)SteeringSystem（轉(zhuǎn)向系）SteeringgearSteeringshaftSteeringwheelUniversaljointTierod轉(zhuǎn)向器轉(zhuǎn)向傳動(dòng)軸轉(zhuǎn)向盤萬(wàn)向節(jié)轉(zhuǎn)向橫拉桿PowerSteeringGear（動(dòng)力轉(zhuǎn)向系）SteeringgearPitmanarmDraglinkSteeringknuckleAckermanarmSteeringshaftSteeringcylinderSteeringpumpSteeringtierodwheel機(jī)械轉(zhuǎn)向器轉(zhuǎn)向搖臂轉(zhuǎn)向直拉桿轉(zhuǎn)向節(jié)臂梯形臂轉(zhuǎn)向軸轉(zhuǎn)向油缸轉(zhuǎn)向油泵轉(zhuǎn)向橫拉桿轉(zhuǎn)向盤BrakeSystem（制動(dòng)系）BrakefluidreservoirMastercylinderBrakelineVacuumpowerboosterBrakepedalHandle制動(dòng)液儲(chǔ)箱制動(dòng)總泵制動(dòng)管路真空助力器制動(dòng)踏板拉手CaliperSlidepinDiscWheelstudBrakedrumWheelcylinder卡鉗導(dǎo)向銷盤車輪緊固螺栓制動(dòng)鼓制動(dòng)分泵HowCVTWorksTraditionaltransmissionsuseagearsetthatprovidesagivennumberofratios(orspeeds).Thetransmission(orthedriver)shiftsgearstoprovidethemostappropriateratioforagivensituation:Lowestgearsforstartingout,middlegearsforaccelerationandpassing,andhighergearsforfuel-efficientcruising.傳統(tǒng)變速箱使用提供既定比率（或速度）的整套齒輪。變速箱（或傳動(dòng)箱）變換齒輪，對(duì)既定的情況提供最適當(dāng)?shù)谋嚷剩鹤畹偷凝X輪用于起步，中間的齒輪用于加速和超車，更高的齒輪用于省油的巡航。ThoughthereareseveraltypesofCVTs,mostcarsuseapairofvariable-diameterpulleys,eachshapedlikeapairofopposingcones,withametalbeltorchainrunningbetweenthem(Fig.9-6)[1].Onepulleyisconnectedtotheengine(inputshaft),theothertothedrivewheels(outputshaft).雖然有幾種CVT型號(hào)，大部分汽車都是使用一對(duì)可變徑滑輪，形狀象一對(duì)相向的圓錐，而且在兩者之間有一條金屬帶或鏈在運(yùn)轉(zhuǎn)。一個(gè)滑輪連接著發(fā)動(dòng)機(jī)（輸入軸），另一個(gè)連接著驅(qū)動(dòng)輪（輸出軸）。Thehalvesofeachpulleyaremoveable;asthepulleyhalvescomeclosertogetherthebeltisforcedtoridehigheronthepulley,effectivelymakingthepulley'sdiameterlarger.每個(gè)滑輪的半部都是可移動(dòng)的：當(dāng)滑輪的兩個(gè)半部相互移近時(shí)，傳動(dòng)帶被推向滑輪上更高的地方，從而有效增大滑輪的直徑。Changingthediameterofthepulleysvariesthetransmission'sratio(thenumberoftimestheoutputshaftrevolvesforrevolutionoftheengine),inthesamewaythata10-speedbikeroutesthechainoverlargerorsmallergearstochangetheratio.滑輪直徑的變換，改變了變速箱的比率（隨著時(shí)間的推移，輸出軸隨著發(fā)動(dòng)機(jī)的轉(zhuǎn)動(dòng)而轉(zhuǎn)動(dòng)），就像十速自行車將車鏈放在更大或更小的齒輪上以改變比率。Makingtheinputpulleysmallerandtheoutputpulleylargergivesalowratio(alargenumberofenginerevolutionsproducingasmallnumberofoutputrevolutions)forbetterlow-speedacceleration.Asthecaraccelerates,thepulleysvarytheirdiametertolowertheenginespeedascarspeedrises.將輸入滑輪變小和輸出滑輪變大，可以提供低比率（發(fā)動(dòng)機(jī)的大量轉(zhuǎn)動(dòng)帶動(dòng)少量輸出轉(zhuǎn)動(dòng)）以得到更好的低速加速度。當(dāng)汽車加速時(shí)，滑輪改變直徑，以便在汽車速度提升時(shí)降低發(fā)動(dòng)機(jī)速度。。Thisisthesamethingaconventionalautomaticormanualtransmissiondoes,butwhileaconventionaltransmissionchangestheratioinstagesbyshiftinggears,theCVTcontinuouslyvariestheratio-hencethename"continuouslyvariabletransmission".這與傳統(tǒng)變速箱或手動(dòng)變速箱的工作相同，但是傳統(tǒng)變速箱是通過(guò)變換齒輪、按檔位改變比率時(shí)，而CVT不斷地改變比率－－正如其名。AdvantagesoftheCVTEnginesdonotdevelopconstantpoweratallspeeds;theyhavespecificspeedswheretorque,horsepowerandfuelefficiencyareattheirhighestlevels.Becausetherearenogearstotieagivenroadspeeddirectlytoagivenenginespeed,theCVTcanvarytheenginespeedasneededtoaccessmaximumpoweraswellasmaximumfuelefficiency.發(fā)動(dòng)機(jī)并不是在所有的速度下都連續(xù)產(chǎn)生動(dòng)力。在扭矩、馬力和燃油經(jīng)濟(jì)性最佳的情況下，發(fā)動(dòng)機(jī)有特定的速度。由于沒(méi)有齒輪可以把車速直接和發(fā)動(dòng)機(jī)的速度綁定，無(wú)極變速器可以通過(guò)調(diào)節(jié)發(fā)動(dòng)機(jī)的速度以獲取最佳的動(dòng)力和最好的燃油經(jīng)濟(jì)性。ThisallowstheCVTtoprovidequickeraccelerationthanaconventionalautomaticormanualtransmissionwhiledeliveringsuperiorfueleconomy.這使得CVT比傳統(tǒng)變速器或者手動(dòng)變速器提交更快的加速度，同時(shí)燃油經(jīng)濟(jì)性也更好。DisadvantagesoftheCVTTheCVT'sbiggestproblemhasbeenuseracceptance.BecausetheCVTallowstheenginetorevatanyspeed,thenoisescomingfromunderthehoodsoundoddtoearsaccustomedtoconventionalmanualandautomatictransmissions.CVT最大的問(wèn)題在于用戶接受性。由于CVT夠能使發(fā)動(dòng)機(jī)在任何速度下加速，從引擎蓋下傳出的聲音，對(duì)于習(xí)慣了傳統(tǒng)變速器或者手動(dòng)變速器的人來(lái)說(shuō)，聽(tīng)起來(lái)很奇怪。Flooringanautomaticcarbringsalurchandasuddenburstofpower,whereasCVTsprovideasmooth,rapidincreasetomaximumpower.Tosomedriversthismakesthecarfeelslower,whileinfactaCVTwillgenerallyout-accelerateanautomatic.自動(dòng)變速器油門踩到底的時(shí)候，會(huì)使人忽然傾斜，動(dòng)力忽然爆發(fā)，但是無(wú)極變速器能順暢地、快速地加速到最大動(dòng)力。對(duì)某些司機(jī)來(lái)說(shuō)，這使得車速感覺(jué)較慢，但是事實(shí)上，CVT的加速速度比自動(dòng)加速器要快AutomakershavegonetogreatlengthstomaketheCVTfeelmorelikeaconventionaltransmission.MostCVTsaresetuptocreepforwardwhenthedrivertakeshisorherfootoffthebrake.汽車制造商們竭盡全力使CVT感覺(jué)更像傳統(tǒng)的變速器。大部分的CVT在司機(jī)們把腳從剎車上拿下來(lái)以后還能爬行前進(jìn)。Thisprovidesasimilarfeeltoaconventionalautomatic,andservesasanindicatorthatthecarisingear.OtherCVTsoffera"manual"modethatsimulatesmanualgearchanges.這使得CVT感覺(jué)更像是傳統(tǒng)的變速器，并且給人感覺(jué)，汽車還有變速器齒輪。有的CVT提供手動(dòng)模式，模擬手動(dòng)換擋。BecauseearlyautomotiveCVTswerelimitedastohowmuchhorsepowertheycouldhandle,therehasbeensomeconcernaboutthelong-termreliabilityoftheCVT.由于早期的變速器僅限于關(guān)注能應(yīng)對(duì)多大馬力，因此就有人質(zhì)疑CVT的長(zhǎng)期可靠性。AdvancedtechnologyhasmadetheCVTmuchmorerobust.NissanhasmorethanamillionCVTsinservicearoundtheworldandusestheminpowerfulcarssuchasthe255horsepowerMaxima,andsaystheirlong-termreliabilityiscomparabletoconventionaltransmissions.先進(jìn)的技術(shù)使得CVT更加牢固。尼桑在全世界擁有一百萬(wàn)臺(tái)無(wú)極變速器，并使用于大功率的汽車上，比如255馬力的Maxima，并認(rèn)為它們的長(zhǎng)期可靠性可以和傳統(tǒng)變速器媲美。gotogreatlengthstodosth.竭盡全力做某事Theywenttogreatlengthstokeeptheaffairsecret.He'llgotogreatlengthtogetthejobdone.serveas充當(dāng),用作,成為,起…作用Shehasservedasamodelforseveralpainters.Letthisincident

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areservationofticketsforitscustomers.Continuouslyvariabletransmissionsaremoreefficientandprovidemoretorqueandpowerthantraditionaltransmissions.和傳統(tǒng)變速器相比，無(wú)極變速器效率更高，并且能提供更大的扭矩和動(dòng)力。By2012,CVTsareexpectedtohavea20percentshareoftheJapanesemarket,a4percentshareoftheNorthAmericanmarketandlessthana5percentshareoftheEuropeanmarket.到2012年為止，CVT在日本的市場(chǎng)份額有望達(dá)到20%，在北美的份額達(dá)到4%，在歐洲的份額應(yīng)該小于5%。Whatimpressionoftheengine?complicatedpowerPre-questionsWhatarethetypesoftheengine?electricmotors,steamengines,andinternalcombustionenginesWhat’stheinternalcombustionengine?

burnsfuelwithinthecylindersandconvertstheexpandingforceofthecombustionintorotaryforceusedtopropelthevehicle.Pre-questionsWords&phrasesIntakemanifold[‘m?n?f??ld]進(jìn)氣管throttle

[‘θr?t(?)l]valve[v?lv]節(jié)氣門Cylinder[‘s?l?nd?]headcover氣缸蓋罩Distributor

[d?‘str?bj?t?]分電器Cylindercover氣缸蓋Vent-pipe

[‘ventpaip]排氣管Cylinderblock氣缸體Sparkplug

[pl?g]火花塞timingdrivingroomcover正時(shí)傳動(dòng)室蓋Timingbelt正時(shí)齒輪帶Words&phrasesCamshaft

[‘k?m?ɑ?ft]凸輪軸Campulley[‘p?l?]凸輪帶輪Crankshaft

[‘kr??k?ɑ?ft]曲軸Crankshafttimingbeltgearwheel曲軸正時(shí)齒形帶輪Flywheel飛輪Waterjacket水套Piston['p?st(?)n]活塞Sump[s?mp]油底殼Mechanism

[‘mek(?)n?z(?)m]機(jī)械裝置，原理Connectingrod連桿lubricating

[‘lu:brikeiti?]

system潤(rùn)滑系統(tǒng)Single-cylinderenginecylinderpistonPistonpinConnectingrodcrankshaftOilpipeIntakevalveExhaustvalveTiminggearOilpumpwhatisthepowersourceofautomobileandhowtoproduce?pistonpistonpinconnectingrodcrankshaftEnginePowerisproducedbythelinearmotionofapistoninacylinder.

Theconnectingrodtransmitstheup-and-downmotionofthepistontothecrankshaft,whichchangesitintorotarymotion.

Pre-questionsTheenginecomprisestwomechanismandfivesystems,whatarethey?crankshaftandconnectingrodmechanism（曲軸連桿裝置）,valvegear(閥動(dòng)裝置）,coolingsystem,lubricatingsystem,fuelsystem,startingsystem,ignitionsystemPre-questions9connectingrodflywheelcrankshaftpistonintakevalveexhaustvalvepushrodtappettiminggears■

Valvegear

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Connectingrod

EnginecoolingsystemEnginelubricatingsystemFuelsupplysystemValvegearpistoncrankshaftdistributorsumptiminggearcrankshaftandconnectingrodmechanismvalvegearfuelsystemSparkplugexhaustmanifoldIII.ExercisesTranslatethefollowingexpressionsintoChinese.活塞曲軸分電器油底殼正時(shí)齒輪曲柄連桿機(jī)構(gòu)配氣機(jī)構(gòu)燃油系統(tǒng)火花塞排氣歧管1-cylinderheadcover2-piston3-timingbelt4-waterpump5-sump6-oilpump7-crankshaft8-flywheel9-distributor10-valveIII.ExercisesReadingHowanEngineWorksTheinternalcombustionengine,asitsnameindicates,burnsfuelwithinthecylindersandconvertsexpandingforceofthecombustionintorotaryforceusedtopropelthevehicle.Theactionstakingplaceintheenginecylindercanbeclassifiedintofourstages,orstroke.“stroke”referstopistonmovement;pel[pr?‘pel]v.推動(dòng)，驅(qū)動(dòng)limitingposition極限位置Theinternalcombustionengine,asitsnameindicates,burns

fuelwithinthecylindersandconvertstheexpandingforceofthecombustionintorotaryforceusedtopropelthevehicle.譯文：內(nèi)燃機(jī)，顧名思義，就是燃料在氣缸內(nèi)部燃燒，并且把燃燒時(shí)的膨脹力轉(zhuǎn)化為驅(qū)動(dòng)車輛的旋轉(zhuǎn)力。II.TextExplanationConvert…..into….①轉(zhuǎn)變；變換Thatbuildinghasbeenconvertedintoaschool.那座樓房改成學(xué)校了。②兌換IwanttoconvertsomeHongKongdollarsintoAmericandollars.我想把一些港元換成美元。③改變信仰、黨派或意見(jiàn)等Shemanagedtoconverthimtoheropinion.她終于設(shè)法說(shuō)服了他接受她的意見(jiàn)。II.TextExplanationReadingHowanEngineWorks.Theactionstakingplaceintheenginecylindercanbeclassifiedintofourstages,orstroke.發(fā)動(dòng)機(jī)氣缸內(nèi)的工作過(guò)程可以分為四個(gè)過(guò)程或沖程。beclassifiedinto….①分類為、被分成Memorycan

beclassifiedinto

short-termandlong-termmemory.記憶可分為長(zhǎng)期記憶和短期記憶。II.TextExplanationReadingHowanEngineWorks“Stroke”referstopistonmovement;astrokeoccurswhenthepistonmovesfromonelimitingpositiontotheother.“沖程”指的是活塞的運(yùn)動(dòng)。當(dāng)活塞從一個(gè)極限位置移動(dòng)到另一個(gè)極限位置，即完成了一次沖程。ReadingTheupperlimitofpistonmovementiscalledTDC(topdeadcenter).ThelowerlimitofpistonmovementiscalledBDC(bottomdeadcenter).AstrokeispistonmovementfromTDCtoBDCorfromBDCtoTDC.活塞運(yùn)動(dòng)的上極限位置被稱為TDC（上止點(diǎn)）?；钊南聵O限位置被稱為BDC（下止點(diǎn)）。一個(gè)沖程是指活塞從上止點(diǎn)運(yùn)動(dòng)到下止點(diǎn)或者從下止點(diǎn)運(yùn)動(dòng)到上止點(diǎn)。ReadingInotherwords,thepistoncompletesastrokeeachtimeitchangesitsdirectionofmotion.換句話說(shuō)，活塞每完成一次沖程就會(huì)改變運(yùn)動(dòng)方向。Inotherwords

Inotherwords,theyremainrelativelyconstantorstatic.

換句話說(shuō)，它們相對(duì)的穩(wěn)定、靜止。

Inotherwords,wehaveadheredtoscientificsocialism.

也就是說(shuō)，我們堅(jiān)持了科學(xué)社會(huì)主義ReadingWheretheentirecycleofeventsinthecylinderrequiresfourstrokes(ortwocrankshaft

revolutions),theengineiscalledafour-stroke-cycleengine.Thefourpistonstrokesareintake,compression,powerandexhaust.氣缸內(nèi)的全部循環(huán)運(yùn)動(dòng)需要四沖程（或稱為二次曲軸轉(zhuǎn)動(dòng)），這種發(fā)動(dòng)機(jī)稱為四沖程循環(huán)發(fā)動(dòng)機(jī)?；钊乃臎_程分別為進(jìn)氣行程、壓縮行程、做功行程和排氣行程。ReadingIntakestroke.Ontheintakestroke,theintakevalvehasopened,thepistonismovingdownward,andamixtureofairandvaporizedgasolineisenteringthecylinderthroughthevalveport.Themixtureofairandvaporizedgasolineisdeliveredtothecylinderbythefuelsystemandcarburetor.Vaporized[‘ve?p?ra?zd]adj.汽化的carburetor[,kɑ?bj?‘ret?]n.汽化器ReadingOntheintakestroke,theintakevalvehasopened,thepistonismovingdownward,andamixtureofairandvaporizedgasolineisenteringthecylinderthroughthevalveport.“在進(jìn)氣行程中，進(jìn)氣門打開(kāi)，活塞向下移動(dòng)，可燃混合氣通過(guò)進(jìn)氣門進(jìn)入氣缸。ReadingThemixtureofairandvaporizedgasolineisdeliveredtothecylinderbythefuelsystemandcarburetor.適當(dāng)濃度的可燃混合氣是由燃料系統(tǒng)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[r?‘v?lv??]adj.旋轉(zhuǎn)的volume

[‘v?lju?m]n.量AfterthepistonreachesBDC,orthelowerlimitofitstravel.Itbeginstomoveupwards.Asthishappens,theintakevalvecloses.Theexhaustvalveisalsoclosed,sothatthecylinderissealed.在活塞到達(dá)下止點(diǎn)時(shí)或者是活塞下限時(shí)，活塞開(kāi)始向上運(yùn)動(dòng)。同時(shí)，進(jìn)氣門關(guān)閉，排氣門也關(guān)閉，所以這時(shí)的汽缸是封閉的。Asthepistonmovesupward(pushednowbytherevolvingcrankshaftandconnectingrod),theair-fuelmixtureiscompressedtoaslittleasone-tenthofitsoriginalvolume,orevenless.當(dāng)活塞向上運(yùn)動(dòng)時(shí)(這時(shí)是由轉(zhuǎn)動(dòng)的曲軸和連桿推動(dòng)活塞)，可燃混合氣被壓縮。當(dāng)活塞到達(dá)上止點(diǎn)時(shí)，可燃混合氣被壓縮到有原體積的十分之下甚至更少。Whentheair-fuelmixtureiscompressed,notonlydoesthepressureinthecylindertoup,butthetemperatureofthemixturealsoincreases.當(dāng)油氣混合燃料被壓縮時(shí)，不僅汽缸里的壓力上升，可燃混合氣的溫度也隨之增加了。Powerstroke.AsthepistonreachesTDConthecompressionstroke,andelectricsparkisproducedatthesparkplug.Theignitionsystemdeliversahigh-voltagesurgeofelectricitytothesparkplugtoproducethespark.Thesparkignitestheair-fuelmixture.Itnowbeginstoburnveryrapidly,andthecylinderpressureincreasedtoasmuchas3-5MPaorevenmore.Thisterrificpushagainstthepistonforcesitdownward,andapowerimpulseistransmittedthroughtheconnectingrodtothecrankpinonthecrankshaft.Thecrankshaftisrotatedasthepistonispusheddownbythepressureaboveit.AsthepistonreachesTDConthecompressionstroke,andelectricsparkisproducedatthesparkplug.Theignitionsystemdeliversahigh-voltagesurgeofelectricitytothesparkplugtoproducethespark.當(dāng)活塞到達(dá)壓縮行程的上止點(diǎn)時(shí)，火花塞產(chǎn)生電火花。電火花是由點(diǎn)火系統(tǒng)向火花塞提供高壓電脈沖而產(chǎn)生的。

Thesparkignitestheair-fuelmixture.Itnowbeginstoburnveryrapidly,andthecylinderpressureincreasedtoasmuchas3-5MPaorevenmore.

電火花點(diǎn)燃可燃混合氣?？扇蓟旌蠚忾_(kāi)始發(fā)生劇烈燃燒，氣缸內(nèi)壓力達(dá)到3-5兆帕，甚至更高。Thisterrificpushagainstthepistonforcesitdownward,andapowerimpulseistransmittedthroughtheconnectingrodtothecrankpinonthecrankshaft.Thecrankshaftisrotatedasthepistonispusheddownbythepressureaboveit.作用于活塞上強(qiáng)大的推動(dòng)力推動(dòng)活塞向下運(yùn)動(dòng)，并將這一推力通過(guò)連桿傳到曲軸上的連桿軸頸上。因此，當(dāng)活塞受壓向下運(yùn)動(dòng)時(shí)，推動(dòng)曲軸轉(zhuǎn)動(dòng)。Exhauststroke.AsthepistonreachesBDCagain,theexhaustvalveopens.Now,asthepistonmovesupontheexhauststroke,itforcestheburnedgasesoutofthecylinderthroughtheexhaust-valveport.Then,whenthepistonreachesTDC,theexhaustvalveclosedandtheintakevalveopens.Now,afreshchargeofair-fuelmixturewillbedrawnintothecylinderasthepistonmovesdowntowardBDC.Thisfourstrokecycleofpistonwithinthecylinderisrepeatedtimeandagaintoputthevehicleforward.AsthepistonreachesBDCagain,theexhaustvalveopens.Now,asthepistonmo