专业英语ppt课件汽车专业英语ppt课件-与汽车专业英语读译教程配套-宋进桂制作15-U9TA

5月12日14时28分，我国四川发生里氏8级地震在地震发生的这一周内，3.4万同胞遇难，22万余人受伤国务院已决定：5月19日21日为全国哀悼日5月19日14时28分，全国人民为地震灾区遇难同胞默哀3分钟2008年5月19日12时,沉痛悼念汶川大地震遇难同胞,UNIT9AUTOMATICTRANSMISSIONSTEXTAAutomaticTransmission(AT),PROFESSIONALENGLISH,UNIT8AUTOMATICTRANSMISSIONSTEXTAAutomaticTransmission(AT)TorqueConverterPlanetaryGearHydraulicSystemServosandAccumulatorsHydraulicControlSystemElectronicControlSystem,本次课学习内容,本次课学习目标,掌握自动变速器的有关英文专业词汇能够较好地用已知翻译技巧进行课文翻译训练快速阅读能力，较高的阅读速度,NEWWORDS,PHRASESANDEXPRESSIONS,AutomaticTransmission(AT)Intodaysautomobile,theautomatictransmissionisbyfarthemostcomplicatedmechanicalcomponent.Itisatypeoftransmissionthatshiftsitself.Automatictransmissionortransaxlehasfourbasicsystems-atorqueconverter,agearsystem,ahydraulicsystemandanelectronicsystem(Fig.9-1).TORQUECONVERTERThetorqueconverterreplacestheconventionalclutch.Ithasthreefunctions:1.Itallowstheenginetoidlewiththevehicleatastandstill,evenwiththetransmissionortransaxleingear1.2.Itallowsthetransmissionortransaxletoshiftfromrange-to-rangesmoothly,withoutrequiringthatthedriverclosethethrottleduringtheshift.3.Itmultipliesenginetorquetoanincreasingextentasvehiclespeeddropsandthrottleopeningisincreased.Thishastheeffectofmakingthetransmissionortransaxlemoreresponsiveandreducestheamountofshiftingrequired.,Driveplate2.Converterlockupclutch3.TorqueconverterP.ImpellerR.StatorT.Turbine4.ClutchA5.ClutchB6.ClutchC7.ClutchC8.ClutchD9.Planetarygearset10.Planetarygearset,fourthgear11.ClutchE12.ClutchF13.Output14-17.One-wayclutchFig.9-1Componentsofatypicalautomatictransmission,Thetorqueconverterisametalcasewhichisshapedlikeaspherethathasbeenflattenedonoppositesides,itisboltedtotherearendoftheenginescrankshaft.Generally,theentiremetalcaserotatesatenginespeedandservesastheenginesflywheel.Thecasecontainsthreesetsofblades(Fig.9-2).Onesetisattacheddirectlytothecase.Thissetformsthetorusorpump.Anothersetisdirectlyconnectedtotheoutputshaft,andformstheturbine.Thethirdsetismountedonahubwhich,inturn,ismountedonastationaryshaftthroughaone-wayclutch.Thisthirdsetisknownasthestator.Apump,whichisdrivenbytheconverterhubatenginespeed,keepsthetorqueconverterfullofautomatictransmissionfluidatalltimes.Fluidflowscontinuouslythroughtheunittoprovidecooling.Underlowspeedacceleration,thetorqueconverterfunctionsasfollows:Thetorusisturningfasterthantheturbine.Itpicksupfluidatthecenteroftheconverterand,throughcentrifugalforce,slingsitoutward.Sincetheouteredgeoftheconvertermovesfasterthantheportionsatthecenter,thefluidpicksupspeed.,Fig.9-2Thetorqueconverterhousingisrotatedbytheenginescrankshaft,andturnstheimpeller.Theimpellerthenspinstheturbine,whichgivesmotiontotheturbineshaft,drivingthegears,Thefluidthenenterstheouteredgeoftheturbineblades;itthentravelsbacktowardthecenteroftheconvertercasealongtheturbineblades.Inimpingingupontheturbineblades,thefluidlosestheenergypickedupinthetorus.,Ifthefluidwasnowreturneddirectlyintothetorus,bothhalvesoftheconverterwouldhavetoturnatapproximatelythesamespeedatalltimes,andtorqueinputandoutputwouldbothbethesame.Inflowingthroughthetorusandturbine,thefluidpicksuptwotypesofflow,orflowintwoseparatedirections.Itflowsthroughtheturbineblades,anditspinswiththeengine.Thestator,whosebladesarestationarywhenthevehicleisbeingacceleratedatlowspeeds,convertsonetypeofflowintoanother2.Insteadofallowingthefluidtoflowstraightbackintothetorus,thestatorscurvedbladesturnthefluidalmost90towardthedirectionofrotationoftheengine.Thusthefluiddoesnotflowasfasttowardthetorus,butisalreadyspinningwhenthetoruspicksitup.Thishastheeffectofallowingthetorustoturnmuchfasterthantheturbine.Thisdifferenceinspeedmaybecomparedtothedifferenceinspeedbetweenthesmallerandlargergearsinanygeartrain.Theresultisthatenginepoweroutputishigher,andenginetorqueismultiplied.,Asthespeedoftheturbineincreases,thefluidspinsfasterandfasterinthedirectionofenginerotation.Asaresult,theabilityofthestatortoredirectthefluidflowisreduced.Undercruisingconditions,thestatoriseventuallyforcedtorotateonitsone-wayclutchinthedirectionofenginerotation.Undertheseconditions,thetorqueconverterbeginstobehavealmostlikeasolidshaft,withthetorusandturbinespeedsbeingalmostequal.PLANETARYGEARTheabilityofthetorqueconvertertomultiplyenginetorqueislimited.Also,theunittendstobemoreefficientwhentheturbineisrotatingatrelativelyhighspeeds.Therefore,aplanetarygearboxisusedtocarrythepoweroutputoftheturbinetothedriveshaft.Planetarygearsfunctionverysimilarlytoconventionaltransmissiongears.However,theirconstructionisdifferentinthatthreeelementsmakeuponegearsystem,and,inthatallthreeelementsaredifferentfromoneanother3.,Thethreeelementsare:anoutergearthatisshapedlikeahoop,withteethcutintotheinnersurface;asungear,mountedonashaftandlocatedattheverycenteroftheoutergear;andasetoffourplanetgears,heldbypinsinaring-likeplanetcarrier,meshingwithboththesungearandtheoutergear（Fig.9-3）.Eithertheoutergearorthesungearmaybeheldstationary,providingmorethanonepossibletorquemultiplicationfactorforeachsetofgears.Also,ifallthreegearsareforcedtorotateatthesamespeed,thegearsetforms,ineffect,asolidshaft.Mostautomaticsusetheplanetarygearstoprovidevariousreductionsratios.Bandsandclutchesareusedtoholdvariousportionsofthegearsetstothetransmissioncaseortransaxlecaseortotheshaftonwhichtheyaremounted4.Shiftingisaccomplished,then,bychangingtheportionofeachplanetarygearsetwhichisheldtothecaseortotheshaft.,Fig.9-3Planetarygearsworkinasimilarfashiontomanualtransmissiongears,butarecomposedofthreeparts,HYDRAULICSYSTEMServosandAccumulatorsTheservos（Fig.9-4）arehydraulicpistonsandcylinders.Theyresemblethehydraulicactuatorsusedonmanyothermachines,suchasbulldozers.Hydraulicfluidentersthecylinder,underpressure,andforcesthepistontomovetoengagethebandorclutches.,Fig.9-4Servos,operatedbypressure,areusedtoapplyorreleasethebands,toeitherholdtheringgearorallowittorotate,Theaccumulatorsareusedtocushiontheengagementoftheservos.Theautomatictransmissionortransaxlefluid(ATF)mustpassthroughtheaccumulatoronthewaytotheservo.Theaccumulatorhousingcontainsathinpistonwhichissprungawayfromthedischargepassageoftheaccumulator.Whenfluidpassesthroughtheaccumulatoronthewaytotheservo,itmustmovethepistonagainstspringpressure,andthisactionsmoothesouttheactionoftheservo.,HydraulicControlSystemThehydraulicpressureusedtooperatetheservoscomesfromthemainoilpump.Thisfluidischanneledtothevariousservosthroughtheshiftvalves.Thereisgenerallyamanualshiftvalvewhichisoperatedbytheselectorleverandanautomaticshiftvalveforeachautomaticupshiftthetransmissionortransaxleprovides.Therearetwopressureswhichaffecttheoperationofthesevalves.Oneisthegovernorpressurewhichisaffectedbyvehiclespeed.Theotheristhemodulatorpressurewhichisaffectedbyintakemanifoldvacuumorthrottleposition.Governorpressureriseswithanincreaseinvehiclespeed,andmodulatorpressurerisesasthethrottleisopenedwider.Byrespondingtothesetwopressures,theshiftvalvescausetheupshiftpointstobedelayedwithi