汽車專業(yè)英語配套教學課件

姚嘉馬麗麗主編北京大學出版社汽車專業(yè)英語Unite1BasicStructureofAutomobile1.1Structuraldrawingandterminology1.frontwheel(前車輪)2.engine(發(fā)動機)3.clutch(離合器)4.transmission(變速器)5.steeringwheel(方向盤)6.body(車身)7.rearsuspension(后懸架)8.rearwheelarrester(后輪制動器)9.rearwheel(后輪)10.finaldriveanddifferent(主減速及差速器)11.transmissionshaft(傳動軸)12.sub-frame(副車架)13.frontwheelarrester(前輪制動器)14.frontsuspension(前懸架)Fig.1-1Overallstructureofaclassiccar1.radiator(散熱器)2.powersteering(動力轉向器)3.lineshaft(傳動軸)4.exhaustsystem(排氣系統(tǒng))5.differential(差速器)6.gastank(油箱)7.rearaxle(后軸)8.shockabsorber(減震器)9.tire(車輪)10.hydraulicconverter(液力變矩器)11.transmission(變速器)12.crankcase(曲軸箱)13.oilpan(油盤)14.mastercylinder(制動缸)Fig.1-2Structureofaclassiccar(viewfrombelow)1.2BasicStructureofautomotiveAnautomotiveisakindofroadvehicleusuallywithfourwheelswhichisdrivenbyanengine.In1886,aGermanyengineer,GottliebDaimler,inventedthefirstquadriccycleautomobile,whichmeansthatthecarindustrycameintobeing.Nowadaysthecarindustryaroundtheworldhasatremendousdevelopment,andithasbeenthemajorestate,especiallyindevelopedcountries,whicharefamousbyBMW,BenzandVolkswageninGerman,GM,FordandChryslerinAmerica,Toyota,Nissan,MitsubishiandHondainJapan.Withtherapiddevelopmentoftechnology,theautomobilehasbecomeanimportantsymbolofmodernscienceandtechnology.Automobilearethesameinstructure,althoughtheyarequitedifferentinthestyleanddesign.Inotherwords,anyautomobileiscomposedoffoursections,suchasengine,chassis,bodyandelectricalsystem.汽車是一種行駛在道路上，具有四個發(fā)動機驅動的輪子的交通工具。1886年，德國的一位工程師，戈特利布·戴姆勒，發(fā)明了二沖程汽車，意味著汽車工業(yè)的誕生。如今，汽車工業(yè)在世界各地，尤其是在發(fā)達國家，已經得到巨大的發(fā)展并成為主要產業(yè)，主要有德國的寶馬、奔馳和大眾；美國的通用、福特和克萊斯勒；日本的豐田、日產、三菱和本田。隨著技術的飛速發(fā)展，汽車已經成為現代科學技術的重要象征。1.2.1EngineTheengineistheheartofanautomobile.Thefunctionofanautomotiveengineistoconvertfuelintoenergythatmovestheautomobile.Currentlytheeasiestwaytocreatemotionfromfuelistoburnthefuelinsideanengine.Therefore,anautomotiveengineisaninternalcombustionengine,whichburnsfuelwithinthecylindersandconvertstheexpandingforceofthecombustionintorotaryforceusedtodrivetheautomobile.Theenginesuppliesthepowertomovethevehicle.Thepowerisavailablefromtheenginecrankshaftafterafuel,usuallygasoline,isburnedintheenginecylinders.Mostautomotiveenginesarelocatedatthefrontofthevehicleanddriveeithertherearwheelsorthefrontwheelsthroughadrivetrainorpowertrainmadeupofgears,shafts,andothermechanicalandhydrauliccomponents.Mostautomotivevehiclesarepoweredbyaspark-ignitionfour-stroke-cycleinternalcombustionengine.Theinlinefour-cylinderengineandV-typesix-cylinderenginearethemostwidelyused,withV-8enginesalsocommon.Otherautomotiveengineshavethree,five,ten,andtwelvecylinders.Somepassengercarsandtruckshavedieselengines.Someautomotivespark-ignitionanddieselenginesareequippedwithasuperchargerorturbocharger.發(fā)動機能夠提供驅動車輛的動力。燃料，通常是汽油，在發(fā)動機氣缸內燃燒后驅動曲軸以獲得動力。大多數汽車發(fā)動機位于車輛的前部，通過齒輪、軸以及其它機械和液壓組件組成的傳動系來驅動后輪或前輪。1.2.2ChassisThechassisconsistsofthepowertrainortransmissionsystem,thesuspensionsystem,thesteeringsystemandthebrakesystem.Thefunctionofthechassisisreceivingthepoweroftheengineandmakingthecarmovenormally.Inthetypicalfront-enginefront-drivevehicle,thepowertrainconsistsofaclutchandmanualtransaxle,oratorqueconverterandanautomatictransaxle.Thefinaldriveanddifferentialaredesignedintothetransaxle,anddrivethewheelsthroughhalf-shaftswithconstant-velocity(CV)universaljoints.Thetransmissionisthedeviceinthepowertrainthatprovidesdifferentforwardgearratiosbetweentheengineanddrivewheels,aswellasneutralandreverse.Thetwogeneralclassificationsoftransmissionaremanualtransmission,whichthedrivershiftsbyhand,andautomatictransmission,whichshiftsautomatically.Toshiftamanualtransmission,theclutchmustfirstbedisengaged.However,somevehicleshaveautomaticclutchdisengagementformanualtransmissions,whileothervehicleshavealimitedmanual-shiftcapabilityforautomatictransmissions.底盤由傳動系統(tǒng)、懸架系統(tǒng)、轉向系統(tǒng)和制動系統(tǒng)組成。底盤的作用是接受發(fā)動機的動力，使汽車正常運行。Inthepowertrain,thefinaldriveisthespeed-reductiongearsetthatdrivesthedifferential.Thefinaldriveismadeupofalargeringgeardrivenbyasmallerpinion,orpiniongear.Thisprovidesagearreductionofabout3:1;theexactvaluecanbetailoredtotheengine,transmission,weightofthevehicle,andperformanceorfueleconomydesired.Indriveaxles,thedifferentialisthegearassemblybetweenaxleshaftsthatpermitsonewheeltorotateataspeeddifferentfromthatoftheother(ifnecessary),whiletransmittingtorquefromthefinal-driveringgeartotheaxleshafts.Whenthevehicleiscorneringormakingaturn,thedifferentialallowstheoutsidewheeltotravelagreaterdistancethantheinsidewheel;otherwise,onewheelwouldskid,causingtirewearandpartiallossofcontrol.1.2.2Chassis1.2.3BodyThebodyisequippedonthechassis.Itserverstheobviouspurposeofholdingthedriver,passengersandgoods,providingshelter,comfortandprotectionfortheoccupants.Thebodyprovidesthree-quartersofthevehiclestotalrigidlyinbendingandintorsion.Inthecaseofcollision,itisintendedtoresistandminimizeintrusionsintotheoccupantspace.Thebodyisdesignedtokeeppassengerssafeandcomfortable.Thebodystylingprovidesanattractive,colorful,modernappearanceforthevehicle.Theautomobilebodyistheassemblyofsheet-metal,fiberglass,plastic,orcomposite-materialpanelstogetherwithwindows,doors,seats,trimandupholstery,glass,andotherpartsthatformenclosuresforthepassenger,engine,andluggagecompartments.Theassembledbodystructuremayattachthroughrubbermountstoaseparateorfullframe(body-on-frameconstruction),orthebodyandframemaybeintegrated(unitized-bodyconstruction).Inthelattermethod,theframe,bodyparts,andfloorpanareweldedtogethertoformasingleunitthathasenergy-absorbingfrontandrearstructures,andanchorsfortheengine,suspension,steering,andpower-traincomponents.Athirdtypeofbodyconstructionisthespaceframewhichismadeofweldedsteelstampings.Similartothetubechassisandrollcagecombinationusedinrace-carconstruction,non-load-carryingplasticouterpanelsfastentothespaceframetoformthebody.Theframeisthemainstructuralmembertowhichallothermechanicalchassispartsandthebodyareassembledtomakeacompletevehicle.Inoldervehicledesigns,theframeisaseparaterigidstructure;newerpassenger-cardesignshavetheframeandbodystructurecombinedintoanintegralunit,orunitizedbody.Subframesandtheirassembledcomponentsattachtothesiderailsatthefrontandrearoftheunitizedbody.Thefrontsubframecarriestheengine,transmissionortransaxle,lowerfrontsuspension,andothermechanicalparts.Therearsubframe,ifused,carriestherearsuspensionandrearaxle.1.2.3Body1.2.4ElectricalEquipmentElectricalequipmentconsistsofpowerandelectricalequipment.Thepowerequipmentconsistsofbatteryandgenerator.Theelectricalequipmentconsistsofstartingsystem,ignitionsystem,hornsystem,instrumentation,airconditioner,audio,wiperandotherdevices.Theuseofsolid-stateelectronicdevicesintheautomobilebeganduringthe1960s,whentheelectromechanicalvoltageregulatorofthealternator,wasreplacedbyatransistorizedvoltageregulator.Thiswasfollowedinthe1970sbyelectronicignition,fuelinjection,andcruisecontrol.Sincethen,electronicdevicesandsystemsontheautomobilehaveproliferated.Theseincludeengineandpowertraincontrol,airbags,antilockbraking,tractioncontrol,suspensionandridecontrol,remotekeylessentry,memoryseats,driverinformationandnavigationsystems,cellulartelephoneandmobilecommunicationssystems,andonboarddiagnostics.Theself-diagnosticcapabilityofthevehiclecomputer,power-trainorenginecontrolmodule,orsystemcontrollermaybeaidedbyamemorythatstoresinformationaboutmalfunctionsthathaveoccurredandperhapstemporarilydisappeared.Whenrecalledfromthememory,thisinformationcanhelptheservicetechniciandiagnoseandrepairthevehiclemorequickly,accurately,andreliably.電氣設備包括電源和電氣設備。電源設備包括蓄電池和發(fā)電機，電氣設備包括起動系統(tǒng)、點火系統(tǒng)、喇叭系統(tǒng)、儀器儀表、空調、音響、雨刮器和其他設備。1.3ThevehicleTechnicalParametersOnthevehicle,thereisanameplatetoshowthedateofmultifunctionaldisplays(MFD),theplant,theengine,thechassismodel,thetransaxle,themanufactureshownabove,thecolortrim,thegrossvehicleweightrating(GVWR),thevehiclecapacity,thesizeoftyre,thetyrepressureandsoon.Nowlet'slookatthediagramsofthisunit.1.approachangle(接近角)2.frontoverhang(汽車前懸)3.lengthofbody(車身長)4.heightofbody(車身高)5.groundclearance(離地間隙)6.wheelbase(軸距)7.overalllength(總長)8.rearoverhang(后懸架)9.departureangle(離去角)10.vehicleheight(車高)11.wheeltread(輪距)12.widthofbody(車身寬)13.vehiclewidth(車寬)Fig.1-3Thekeydimensiondataofavehicle1.3.1TheKeyDimensionDataofaVehicle1.crankshaft(曲軸)2.connectingrod(連桿)3.piston(活塞)4.intakevalve(進氣門)5.exhaustvalve(排氣門)6.TDC(上止點)7.BDC(下止點)8.cylinderdiameter(氣缸直徑)

9.pistonstroke(活塞沖程)10.clearancevolume(燃燒室容積)11.sweptvolume(活塞排量)Fig.1-4Engineterms1.3.2EngineTermsTopDeadCenter(TDC).Thepositionofthecrankandpistonwhenthepistonisfarthestawayfromthecrankshaft.上止點指的是活塞離曲軸最遠時活塞頂所處的位置。BottomDeadCenter(BDC).Thepositionofthecrankandpistonwhenthepistonisnearestawayfromthecrankshaft.下止點指的是活塞離曲軸最近時活塞頂所處的位置。SweptVolume.ThevolumebetweenTDCandBDC.氣缸工作容積是指上下止點間所包容的氣缸容積。ClearanceVolume.ThevolumeofspaceabovethepositionwhenitisatTDC.燃燒室容積是指活塞位于上止點時，活塞頂面以上的空間容積。EngineCapacity.Thisisthesweptvolumeofallcylinders.Generallyspeaking,thelargertheenginecapacityis,thehighertheenginepoweris.發(fā)動機排量是指發(fā)動機所有氣缸工作容積的總和，一般來說，排量越大，功率越大。CompressionRatio.Itmeansthatthepistoncompressesthegasmixturewhichismadefromairandfuel(sweptvol+clearancevol)/(clearancevol).壓縮比是指氣缸總容積（氣缸工作容積+燃燒室容積）與燃燒室容積之比。1.crankshaft(曲軸)2.connectingrod(連桿)3.piston(活塞)4.intakevalve(進氣門)5.exhaustvalve(排氣門)6.TDC(上止點)7.BDC(下止點)8.cylinderdiameter(氣缸直徑)

9.pistonstroke(活塞沖程)10.clearancevolume(燃燒室容積)11.sweptvolume(活塞排量)Fig.1-4Engineterms1.3.2EngineTermsEngineTorque.Itmeanstheabilityofturningtheliveaxle.發(fā)動機轉矩是指發(fā)動機轉動驅動橋的能力。SpecificFuelConsumption.Itmeansthefuelconsumptioninthegivendistance.燃油消耗率是指車輛在行駛一定距離所消耗的燃油量。EnginePower.Itmeanstheoutputoftheengineinthegiventime.TheunitofmeasurementiskW.發(fā)動機功率是指發(fā)動機在給定時間內輸出的功率，單位是千瓦。1.crankshaft(曲軸)2.connectingrod(連桿)3.piston(活塞)4.intakevalve(進氣門)5.exhaustvalve(排氣門)6.TDC(上止點)7.BDC(下止點)8.cylinderdiameter(氣缸直徑)

9.pistonstroke(活塞沖程)10.clearancevolume(燃燒室容積)11.sweptvolume(活塞排量)Fig.1-4Engineterms1.3.2EngineTerms1.3.3VehicleLabelingEachvehiclehaslabelswhichtellusthedateandplantofthevehiclemanufacture,type(model),enginenumber,chassisNo.,transoraxlenumber,framenumber,color,trim,GVWR,GAWR,tiresize,tirepressure,andsoon.Theseareveryimportantforthevehicletobeusedandserviced(Fig.1-5).1.chassisnumber(底盤號)2.emissioncontrollabel(排放控制標簽)3.vacuumhoseroutinglabel(真空管路路線標簽)4.safetycertificationlabel(安全認證標簽)5.tireinformationlabel(輪胎信息標簽)6.barcodelabel(條形碼標簽)

7.modelnumberplate(車型牌號)Fig.1-52000Fujicarlabelsandnameplatemountposition姚嘉馬麗麗主編北京大學出版社汽車專業(yè)英語Unite2EngineStructure2.1Structuraldrawingandterminology1.intakeairtank(進氣管)2.throttlevalve(節(jié)流閥)3.cylinderhead(氣缸蓋)4.cylinder(氣缸)5.cylinderblock(氣缸體)6.flywheel(飛輪)7.cylinderjacket(氣缸套)8.piston(活塞)9.oilpan(油底殼)10.crankshaft(曲軸)11.timingbeltpulley(同步皮帶輪)12.crankshaftpulley(曲軸皮帶輪)13.timingbelt(正時皮帶)14.camshaft(凸輪軸)15.timingbeltcover(正時皮帶護罩)16.sparkplug(火花塞)Fig.2-1Theoverallstructureofanengine1.switch(開關)2.heatermachine(暖風機)3.heatermachinepenstoke(暖風機進水管)

4.thermostat(節(jié)溫器)5.waterpump(水泵)6.waterpipe(水管)7.waterswell(水箱)8.waterlid(加水蓋)9.bulgewaterswell(膨脹水箱)10.pressurelimitingvalve(限壓閥)Fig.2-2CoolingSystem1.camshaft(凸輪軸)2.overpressvalve(過壓閥)3.hydraulicswitch(油壓開關)4.filters(濾清器)5.oilsumptank(油底殼)6.oilpump(機油泵)7.overpressvalve(過壓閥)8.backclosingvalve(回油關閉閥)Fig.2-3LubricationSystem2.2ClassificationofEngineThereareavarietyofengines,andmostofthemusethepetroleumfuelandareknownasgasolineengines.Thevaporizedliquidfuelismixedupwiththeair,burntandexpandedtoproducethepowertodrivethecars.Thiskindofengineiscalledtheinternalcombustionengine.Nowadays,carsaremostlyequippedwiththegasolineengines.Theautomobileenginescanbeclassifiedaccordingto:numberofcylinders;arrangementofcylinders;arrangementofvalves;typeofcooling;numberofcycles;typeoffuelburned;typeofignition.有各種各樣的發(fā)動機，其中大部分使用石油燃料，被稱為汽油發(fā)動機。氣化的液體燃料與空氣混合，燃燒和膨脹產生動力驅動汽車。這種發(fā)動機是內燃發(fā)動機。如今，汽車主要配備汽油發(fā)動機。1.2.1Engine1.ClassifiedbytheNumberofCylindersAccordingtothenumberofcylinders,theautomobileenginescanbeclassifiedsinglecylinderengineandmulticylinderengine.2.ClassifiedbytheArrangementofCylindersThetermengineconfigurationreferstothewaythatthecylindersofanenginearearranged.Thecylinderscanbein-line,opposed,oratanangle(V-type).Withinthreebasicarrangements,thereareanumberofvariations.發(fā)動機布置形式是指發(fā)動機氣缸的布置方式，可分為直列式、對置式、V型發(fā)動機，在三種基本的排列類型中，也有一些變動。inlineengine.Somein-lineengineshavetheircylinderhorizontal,sothattheengineismoreorlessonitsside.Thisreducestheoverallheightunderthecab.Themechanicalarrangementoffour-cylinderin-lineiscommonlyusedforpassengercars.直列式發(fā)動機。有一些直列發(fā)動機的氣缸是臥式的，因此發(fā)動機或多或少地處于一側，這樣會減少駕駛室下部的發(fā)動機的總體高度。四缸直列發(fā)動機布置形式常見于小汽車中。Horizontal-OpposedEngine.Thisarrangementhasitscylindersarrangedintwoflatsideswiththecrankshaftbetweenthem.Theengineshownhasashortrigidcrankshaftwithfivebearings.Ahorizontal-opposedenginehasevenfiringimpulsesandgoodbalance.Movementofapistoninonedirectionisopposedbymovementofapistonintheopposeddirection.Horizontal-opposedengines,withtheirflatdesign,givetheenginealowheightandalsohelptokeepthecenterofgravityofthevehiclelow.Alowcenterofgravitygivesthevehiclestability.水平對置式發(fā)動機。這種布置是使氣缸布置于曲軸的兩側。所示發(fā)動機具有含5個軸承的剛性短曲軸。水平對置式發(fā)動機具有均勻的觸發(fā)脈沖和良好的平衡。某一方向上活塞的運行與其對置方向的活塞的運行是相反的。由于其扁平的設計，水平對置式發(fā)動機的高度不高，這樣也使得車輛的中心保持較低，使車輛穩(wěn)定性較好。V-TypeEngine.

WithV-typeengines,thecylindersarearrangedintwoblanksatanangle.Thisreducesthelengthoftheengineandmakesitmorecompact.Thisalsoreducesthelengthofthecrankshaft,whichcanbedesignedtobemorerigidthanalongshaft.V型發(fā)動機。發(fā)動機的布置成一定角度，這樣能夠縮小發(fā)動機的長度，使其更加緊湊，同樣也會縮小曲軸的長度，這樣使得曲軸的設計更加注重剛度而非是長軸。3.ClassifiedbytheArrangementofValvesAccordingtothearrangementofvalves,theautomobileenginescanbeclassifiedintofour-cylinderengine,five-cylinderengine,six-cylinderandsoon.4.ClassifiedbytheNumberofCyclesAccordingtothenumberofcycles,theautomobileenginescanbeclassifiedintotwo-strokecycleengineandfour-strokecycleengine.SeeFig.2-5.a.Two-strokecycleengineb.Four-strokecycleengineFig.2-5Classifiedbythenumberofcycles5.ClassifiedbytheTypeofCoolingAccordingtothetypeofcooling,theautomobileenginescanbeclassifiedintowater-cooledorliquid-cooledengineandair-cooledengine.6.ClassifiedbytheTypeofFuelBurnedAccordingtothetypeoffuelburned,theautomobileenginescanbeclassifiedintogasolineengineanddieselengine.SeeFig.2-6.

Fig.2-6ClassifiedbythetypeofthefuelburnedTheengineisthesourceofpowerthatmakesthewheelsrotateandthecarmove.Theautomobileengineisaninternalcombustionenginebecausethefuel(gasoline)isburnedinsideit.Theburningofgasolineinsidetheengineproduceshighpressureintheenginecombustionchamber.Thishighpressureforcespistontomove,themovementiscarriedbyconnectingrodstotheenginecrankshaft.Thus,thecrankshaftismadetorotate,therotarymotioniscarriedthroughthepowertraintothecarwheelssothattheyrotateandcarmoves.Theenginerequiresfivesystems.Theyarefuelsystem,coolingsystem,lubricationsystem,ignitionsystemandstartingsystem.Thesefivesystemsarediscussedbrieflyinthefollowingunits.Theoverallstructureofanengineisasfollows.SeeFig.2-7.Thecompleteengineassemblyofthemechanicalcomponentsthatmakesuptheengineitselfandalsoanumberofassociatedsystems,thesearethesystemsthatareneededtostarttheengineandalsotocontrolitandkeepitrunning.Themechanicalpartsoftheengineassemblycanbebrokendownintoanumberofsub-assemblies,orgroupofassociatedcomponents,althoughtheseareusuallyreferredtomerelyasassemblies,forexample,cylinder-headassemblyandpistonassembly.Somepartsofanengineareinternal,otherpartsareexternal-thisillustrationidentifiesanumberofexternalparts.2.3ConstructionofEngine

發(fā)動機運轉需要五個系統(tǒng)，分別是燃油系統(tǒng)，冷卻系統(tǒng)，潤滑系統(tǒng)，點火系統(tǒng)和起動系統(tǒng)。1.CylinderBlock

Theengineblockisthemainsupportingstructuretowhichallotherenginepartsareattached.Ithastwomainsections:thecylindersectionandthecrankcasesection.Thecrankcasesectionisusedtohousethecrankshaft,oilpan.Coolingpassagewaysarebuiltwithintheblock.Thesepassageways,alsoknownaswatersockets,surroundthecylinders.Theyallowcoolanttocirculatethroughoutthecylinderareatokeeptheenginecool.Thereisalsoadrilledpassagewaywithinsomeblocksforthecamshaft.Manyoilholesaredrilledinternallysothatenginepartscanbeadequatelylubricated.SeeFig.2-7.1.cylinder(氣缸)2.waterjacket(水套)3.mainoilgallery(主油道)4.blockunderside(機體底面)5.reinforcingrib(橫隔板加強肋)6.headstock(柱軸承座)7.blocksidewall(機體側壁)8.sidewallreinforcerib(側壁加強肋)9.blocktipsurface(機體頂面)Fig.2-7Cylinderblock

機體組是發(fā)動機的支架，是其它發(fā)動機零部件的裝配基體，有兩個主要的部分：氣缸體和曲軸箱。曲軸箱用于裝配曲軸和油底殼，冷卻水道被鑄在氣缸體周圍，也叫做水套，這些水套能夠使冷卻液在氣缸周圍不斷循環(huán)以使發(fā)動機冷卻下來。2.CylinderHeadThecylinderheadisusedtoholdthevalves,andithasportstoallowair,fuelandexhausttomovethroughtheengine.Inaddition,ithascoolantpassages.Fig.2-8showsacylinderhead.Afterthecylinderheadhasbeencast,someareasmustbeseated,sparkplugsandinjectorscanbeinstalled,andinjectorscanbeinstalled,andagoodsealcanbeprovidedtotheblock.1.cylinderheadcover(氣缸蓋罩)2.gasket(密封墊)3.cylinderhead(缸蓋)4.cylinderheadgasket(氣缸蓋墊圈)Fig.2-8Cylinderhead3.PistonandConnectingRodAssemblyThepistonandconnectingrodassemblytransmitsthepowerfromcombustiontothecrankshaft.ItsshowninFig.2-9,mainlyconsistsofpiston,compressionrings,oilcontrolrings,pistonpinandconnectingrod.1.piston(活塞)2.pistonrings(活塞環(huán))3.pistonpin(活塞銷)4.connectingrod(連桿)5.connectingrodbolts(連桿螺栓)6.connectingrodcap(連桿蓋)7.connectingrodbearing(連桿軸承)Fig.2-9PistonandrodassemblyPiston.Pistonfitscloselywithintheenginecylinderorlinerandisabletomovealternatelyupanddowninthecylinder.PistonRings.Thesearetwotypesofpistonrings-compressionandoilcontrolrings.Thecompressionringsareusedtosealthepressuresofcompressionandpower.Theoilcontrolringsareemployedtoscrapeoilfromthecylinderwalls.PistonPin.Itisusedtoconnectpistontoconnectingrod.ConnectingRod.Itisusedtoconnectpistontocrankshaft,anditchangesthereciprocatingmotiontotherotarymotion.4.CrankshaftAssemblyItisboltedtothebottomofthecylinderblock.Thecrankshaftisaone-piececastingorforgingofheart-treatedalloysteelofconsiderablemechanicalstrength.Itmustbestrongenoughtotakethedownwardthrustsofthepistonsduringthepowerstrokeswithoutexcessivedistortion.Inaddition,itmustbecarefullybalancedtoeliminateunduevibrationresultingfromtheweightoftheoffsetcranks.Toprovidebalance,crankshaftshavecounterweightsoppositethecranks.Crankshaftshavedrilledoilpassagesthroughwhichoilcanflowfromthemaintotheconnecting-rod,bearings.Thecrankshaftassemblyincludesthecrankshaft,bearings,flywheel,harmonicbalancer,timinggear,frontandrearseals.Fig.2-10showscrankshaftassembly.1.crankshaftfrontend(曲軸前端)2.frontmainjournal(前軸軸頸)3.oilpassagehole(油道孔)4.crankpin(曲柄銷)5.crankweb(曲柄臂)6.counterweight(平衡錘)7.oilpassageplug(潤滑油孔塞)8.oilpassage(潤滑油孔)9.crankshaftcollar(曲軸后端凸緣)10.flywheel(飛輪)11.flywheelgearring(飛輪齒環(huán))12.flywheellockplate(飛輪鎖板)13.clutchshaftbearing(離合器軸軸承)Fig.2-10Crankshaftassembly5.CamshaftAssembly

Thecamshaftisdrivenbythecrankshaftandusedtoopenandclosethevalves.Mostpistonsaremadefromcastaluminum.Thepiston,throughtheconnectingrod,transferstothecrankshafttheforcecreatedbytheburningfuelmixture.Thisforceturnsthecrankshaft.Thecamshaftassemblyincludesthecamshaft,camshafttiminggear,camshaftbearing,timingchain,andbelt(ifused).SeeFig.2-11.1.camshaftjournal(凸輪軸)2.cam(凸輪)3.oilhole(油孔)4.timinggear(定時齒輪)Fig.2-11Camshaft

凸輪軸是由曲軸驅動，用于開啟和關閉氣門。大多數活塞由鑄鋁制成。通過連桿、活塞將燃油混合氣燃燒產生的動力傳遞給曲軸，使曲軸轉動起來。凸輪軸總成包括凸輪軸、凸輪軸定時齒輪、凸輪軸軸承、正時鏈條和皮帶（如果使用的話）。6.FlywheelTheflowofpowerfromtheenginecylinderisnotsmooth.Althoughthepowerimpulseoverlap(onsixandeight-cylinderengines),thesearetimeswhenmorepowerisbeingdeliveredthanatothertimes.Thistendstomakethecrankshaftspeedupandthenslowdown.However,theflywheelcombatsthetendency.Theflywheelisacomparativelyheavywheelboltedtotherearendofthecrankshaft.Theinertiaoftheflywheeltendstokeepitturningatconstantspeed.Thus,theflywheelabsorbsenergyasthecrankshafttriestospeedupandgivebackenergyasthecrankshafttriestoslowdown.Ineffect,theflywheelabsorbspowerfromtheengineduringthepowerstroke(orspeeduptime)andthengivesittotheengineduringtheotherthreestrokesofthecycle.2.4EngineOperatingPrinciplesTheactionstakingplaceintheenginecylindercanbedividedintofourstages,orstrokes.“Stroke”referstopistonmovement;astrokeoccurswhenthepistonmovesfromonelimitingpositiontotheother.TheupperlimitofpistonmovementiscalledTDC(topdeadcenter).ThelowerlimitofpistonmovementiscalledBDC(bottomdeadcenter).AstrokeispistonmovementfromTDCtoBDCorformBDCtoTDC,inotherwords,thepistoncompletesastrokeeachtime,itchangesitsdirectionofmotion.1.IntakeStrokeThefirststrokeistheintakestroke.Asthepistonstartsdown,theintakevalveopensandtheair-fuelmixtureentersintothecylinder.Whenthepistonreachesthebottomoftheintakestroke,theintakevalvecloses,trappingtheair-fuelmixtureinthecylinder.Duringthisstoke,theexhaustvalvestaysclosed.

第一個沖程是進氣沖程。當活塞開始下降，進氣閥打開，可燃混合氣進入氣缸。當活塞到達進氣沖程底部，進氣閥關閉，封閉可燃混合氣在氣缸中。在這整個過程中，排氣門都保持關閉。2.CompressionStrokeThesecondstrokeisthecompressionstroke.Thepistonmovesupinthecylinderwithbothvalvesclosedandcompressesthetrappedair-fuelmixture.Whenthepistonreachesthetopofthecylinder,thepressurerises.

第二個沖程是壓縮沖程?；钊跉飧變壬仙?，進排氣門均關閉，對被困在氣缸內的可燃混合氣進行壓縮。當活塞到達氣缸頂部，氣缸內壓力上升。3.PowerstrokeThethirdstrokeisthepowerstroke.Neartheendofthecompressionstroke,thesparkplugfires,ignitingthecompressedair-fuelmixturethatproducesapowerfulexplosion.Thecombustionprocesspushesthepistondownthecylinderwithgreatforceturningthecrankshafttoprovidethepowertodrivethecar.第三個沖程是做功沖程。接近壓縮沖程結束時，火花塞跳火，點燃壓縮的可燃混合氣，產生強大的爆炸。燃燒過程推動活塞沿著缸體向下運動，產生巨大的力使得曲軸轉動，進而為汽車行進提供動力。4.ExhaustStrokeThefourthstrokeistheexhauststroke.Withthepistonatthebottomofthecylinder,theexhaustvalveopen,andthepistonmovesupagainandforcestheburnedgasesoutofthecylinder.Thepistontravelsuptothetopofthecylinderpushingalltheexhaustoutbeforeclosingtheexhaustvalveinpreparationforstartingthefour-strokeprocessoveragain.第四沖程是排氣沖程。隨著活塞到達氣缸底部，排氣門打開，活塞再次向上移動，迫使燃燒后的廢氣排出氣缸。在排氣門關閉之前，活塞再繼續(xù)向上運動到達氣缸頂部，并排出所有廢氣，并開始為再一次的四沖程循環(huán)做準備。2.4EngineOperatingPrinciples2.5EngineStartingSystem

Thestartingsystemistheheartoftheelectricalsysteminyourcar.Thestartingsystemperformsthisfunctionbychangingelectricalenergyfromthebatterytomechanicalenergyinthestartingmotor.Thismotorthentransfersthemechanicalenergy,throughgears,totheflywheelontheengine’scrankshaft.Duringcranking,theflywheelrotatesandtheair-fuelmixtureisdrawnintothecylinders,compressed,andignitedtostarttheengine.Mostenginesrequireacrankingspeedofabout200r/min.Thestartingsystemincludesthefollowingcomponents:battery,cableandwires,ignitionswitch,startersolenoidorrelay,startermotor,starterdriveandflywheelringgear.Fig.2-12showsthecomponentsinasimplifiedcrankingsystemcircuit.1.battery(蓄電池)2.startingcircuit(起動電路)3.magneticswitch(電磁開關)4.startermotor(起動電動機)5.controlcircuit(控制電路)6.startingsafetyswitch(起動安全開關)7.ignitionswitch(點火開關)Fig.2-12Startingsystem

起動系統(tǒng)是汽車電器系統(tǒng)的核心。起動系統(tǒng)能夠實現將蓄電池的電能轉變成起動機的機械能，起動機再通過齒輪將機械能傳遞到發(fā)動機曲軸的飛輪上。在起動過程中，飛輪旋轉，空氣混合氣被吸入氣缸，進行壓縮，最后點燃，將發(fā)動機起動。多數發(fā)動機要求其起動速度為20