汽車(chē)專(zhuān)業(yè)英語(yǔ)讀譯教程 第3版 課件 15-U9TA Automatic Transmission (AT)

UNIT9

AUTOMATICTRANSMISSIONS

TEXTA

AutomaticTransmission(AT)

PROFESSIONALENGLISH

UNIT8

AUTOMATICTRANSMISSIONS

TEXTA

AutomaticTransmission(AT)

TorqueConverter

PlanetaryGear

HydraulicSystem

ServosandAccumulators

HydraulicControlSystem

ElectronicControlSystem

本次課學(xué)習(xí)內(nèi)容本次課學(xué)習(xí)目標(biāo)掌握自動(dòng)變速器的有關(guān)英文專(zhuān)業(yè)詞匯能夠較好地用已知翻譯技巧進(jìn)行課文翻譯訓(xùn)練快速閱讀能力，較高的閱讀速度NEWWORDSimpeller[im'pel?]n.推進(jìn)者，葉輪，泵輪stator['steit?]n.定子，導(dǎo)輪pump[p?mp]n.泵，泵輪standstill['st?ndstil]n.停止，停頓sphere[sfi?]n.球，球體，圈子，半球flatten['fl?tn]v.變平，變單調(diào)torus['t?:r?s]n.圓環(huán)面，環(huán)形，葉輪，[植]花托sling[sli?]n.投擲，拋impinge[im'pin?]v.撞擊，打擊fashion['f?∫?n]n.樣子，方式，流行，風(fēng)尚servo['s?:v?u]n.伺服，伺服系統(tǒng)accumulator[?'kju:mjuleit?]n.蓄能器，蓄壓器，[英]蓄電池solenoid['s?ulin?id]n.[電]螺線管

PHRASESANDEXPRESSIONS

driveplate傳動(dòng)板planetarygearset行星齒輪機(jī)構(gòu)one-wayclutch單向離合器planetarygearboxsungear行星齒輪變速器太陽(yáng)輪planetcarrier行星架shiftvalve換檔閥governorpressure調(diào)速器壓力modulatorpressure調(diào)壓閥壓力linepressure主油路壓力Intoday'sautomobile,theautomatictransmissionisbyfarthemostcomplicatedmechanicalcomponent.Itisatypeoftransmissionthatshiftsitself.Automatictransmissionortransaxlehasfourbasicsystems-atorqueconverter,agearsystem,ahydraulicsystemandanelectronicsystem(Fig.9-1).TORQUECONVERTERThetorqueconverterreplacestheconventionalclutch.Ithasthreefunctions:1.Itallowstheenginetoidlewiththevehicleatastandstill,evenwiththetransmissionortransaxleingear[1].2.Itallowsthetransmissionortransaxletoshiftfromrange-to-rangesmoothly,withoutrequiringthatthedriverclosethethrottleduringtheshift.

AutomaticTransmission(AT)

AutomaticTransmission(AT)

3.Itmultipliesenginetorquetoanincreasingextentasvehiclespeeddropsandthrottleopeningisincreased.Thishastheeffectofmakingthetransmissionortransaxlemoreresponsiveandreducestheamountofshiftingrequired.Driveplate2.Converterlockupclutch3.TorqueconverterP.ImpellerR.StatorT.Turbine4.ClutchA5.ClutchB6.ClutchC'7.ClutchC8.ClutchD9.Planetarygearset10.Planetarygearset,fourthgear11.ClutchE12.ClutchF13.Output14-17.One-wayclutchFig.9-1Componentsofatypicalautomatictransmission

AutomaticTransmission(AT)

Thetorqueconverterisametalcasewhichisshapedlikeaspherethathasbeenflattenedonoppositesides,itisboltedtotherearendoftheengine'scrankshaft.Generally,theentiremetalcaserotatesatenginespeedandservesastheengine'sflywheel.Thecasecontainsthreesetsofblades(Fig.9-2).Onesetisattacheddirectlytothecase.Thissetformsthetorusorpump.Anothersetisdirectlyconnectedtotheoutputshaft,andformstheturbine.Thethirdsetismountedonahubwhich,inturn,ismountedonastationaryshaftthroughaone-wayclutch.Thisthirdsetisknownasthestator.Apump,whichisdrivenbytheconverterhubatenginespeed,keepsthetorqueconverterfullofautomatictransmissionfluidatalltimes.Fluidflowscontinuouslythroughtheunittoprovidecooling.Underlowspeedacceleration,thetorqueconverterfunctionsasfollows:

AutomaticTransmission(AT)

AutomaticTransmission(AT)

Thetorusisturningfasterthantheturbine.Itpicksupfluidatthecenteroftheconverterand,throughcentrifugalforce,slingsitoutward.Sincetheouteredgeoftheconvertermovesfasterthantheportionsatthecenter,thefluidpicksupspeed.Thefluidthenenterstheouteredgeoftheturbineblades;itthentravelsbacktowardthecenteroftheconvertercasealongtheturbineblades.Inimpingingupontheturbineblades,thefluidlosestheenergypickedupinthetorus.Fig.9-2Thetorqueconverterhousingisrotatedbytheengine'scrankshaft,andturnstheimpeller.Theimpellerthenspinstheturbine,whichgivesmotiontotheturbineshaft,drivingthegears

AutomaticTransmission(AT)

Ifthefluidwasnowreturneddirectlyintothetorus,bothhalvesoftheconverterwouldhavetoturnatapproximatelythesamespeedatalltimes,andtorqueinputandoutputwouldbothbethesame.Inflowingthroughthetorusandturbine,thefluidpicksuptwotypesofflow,orflowintwoseparatedirections.Itflowsthroughtheturbineblades,anditspinswiththeengine.Thestator,whosebladesarestationarywhenthevehicleisbeingacceleratedatlowspeeds,convertsonetypeofflowintoanother[2].Insteadofallowingthefluidtoflowstraightbackintothetorus,thestator'scurvedbladesturnthefluidalmost90°towardthedirectionofrotationoftheengine.Thusthefluiddoesnotflowasfasttowardthetorus,butisalreadyspinningwhenthetoruspicksitup.Thishastheeffectofallowingthetorustoturnmuchfasterthantheturbine.Thisdifferenceinspeedmaybecomparedtothedifferenceinspeedbetweenthesmallerandlargergearsinanygeartrain.Theresultisthatenginepoweroutputishigher,andenginetorqueismultiplied.

AutomaticTransmission(AT)

AutomaticTransmission(AT)

Asthespeedoftheturbineincreases,thefluidspinsfasterandfasterinthedirectionofenginerotation.Asaresult,theabilityofthestatortoredirectthefluidflowisreduced.Undercruisingconditions,thestatoriseventuallyforcedtorotateonitsone-wayclutchinthedirectionofenginerotation.Undertheseconditions,thetorqueconverterbeginstobehavealmostlikeasolidshaft,withthetorusandturbinespeedsbeingalmostequal.PLANETARYGEARTheabilityofthetorqueconvertertomultiplyenginetorqueislimited.Also,theunittendstobemoreefficientwhentheturbineisrotatingatrelativelyhighspeeds.Therefore,aplanetarygearboxisusedtocarrythepoweroutputoftheturbinetothedriveshaft.Planetarygearsfunctionverysimilarlytoconventionaltransmissiongears.However,theirconstructionisdifferentinthatthreeelementsmakeuponegearsystem,and,inthatallthreeelementsaredifferentfromoneanother[3].

AutomaticTransmission(AT)

Thethreeelementsare:anoutergearthatisshapedlikeahoop,withteethcutintotheinnersurface;asungear,mountedonashaftandlocatedattheverycenteroftheoutergear;andasetoffourplanetgears,heldbypinsinaring-likeplanetcarrier,meshingwithboththesungearandtheoutergear（Fig.9-3）.Eithertheoutergearorthesungearmaybeheldstationary,providingmorethanonepossibletorquemultiplicationfactorforeachsetofgears.Also,ifallthreegearsareforcedtorotateatthesamespeed,thegearsetforms,ineffect,asolidshaft.Mostautomaticsusetheplanetarygearstoprovidevariousreductionsratios.Bandsandclutchesareusedtoholdvariousportionsofthegearsetstothetransmissioncaseortransaxlecaseortotheshaftonwhichtheyaremounted[4].Shiftingisaccomplished,then,bychangingtheportionofeachplanetarygearsetwhichisheldtothecaseortotheshaft.Fig.9-3Planetarygearsworkinasimilarfashiontomanualtransmissiongears,butarecomposedofthreepartsHYDRAULICSYSTEMServosandAccumulatorsTheservos（Fig.9-4）arehydraulicpistonsandcylinders.Theyresemblethehydraulicactuatorsusedonmanyothermachines,suchasbulldozers.Hydraulicfluidentersthecylinder,underpressure,andforcesthepistontomovetoengagethebandorclutches.

AutomaticTransmission(AT)

Fig.9-4Servos,operatedbypressure,areusedtoapplyorreleasethebands,toeitherholdtheringgearorallowittorotate

Theaccumulatorsareusedtocushiontheengagementoftheservos.Theautomatictransmissionortransaxlefluid(ATF)mustpassthroughtheaccumulatoronthewaytotheservo.Theaccumulatorhousingcontainsathinpistonwhichissprungawayfromthedischargepassageoftheaccumulator.Whenfluidpassesthroughtheaccumulatoronthewaytotheservo,itmustmovethepistonagainstspringpressure,andthisactionsmoothesouttheactionoftheservo.

AutomaticTransmission(AT)

AutomaticTransmission(AT)

HydraulicControlSystemThehydraulicpressureusedtooperatetheservoscomesfromthemainoilpump.Thisfluidischanneledtothevariousservosthroughtheshiftvalves.Thereisgenerallyamanualshiftvalvewhichisoperatedbytheselectorleverandanautomaticshiftvalveforeachautomaticupshiftthetransmissionortransaxleprovides.Therearetwopressureswhichaffecttheoperationofthesevalves.Oneisthegovernorpressurewhichisaffectedbyvehiclespeed.Theotheristhemodulatorpressurewhichisaffectedbyintakemanifoldvacuumorthrottleposition.Governorpressureriseswithanincreaseinvehiclespeed,andmodulatorpressurerisesasthethrottleisopenedwider.Byrespondingtothesetwopressures,theshiftvalvescausetheupshiftpointstobedelayedwithincreasedthrottleopenin