AT02 Torque Converter

6TOYOTATechnicalTraining1.Describethefunctionofthetorqueconverter.2.Identifythethreemajorcomponentsofthetorqueconverterthatcontributetothemultiplicationoftorque.3Describetheoperationofeachmajortorqueconvertercomponent.4.Describetheoperationofthelock-upmechanismofthetorqueconverter.5.Distinguishbetweenvortexflowandrotaryflowinatorqueconverter.6.Identifytwosymptomsofafailedstatorone-wayclutch.7.Determinewhenreplacementorserviceoftheconverterisappropriate.Section2TORQUECONVERTERLessonObjectivesTORQUECONVERTERAutomaticTransmissions-Course2627Thetorqueconverterismountedontheinputsideofthetransmissiongeartrainandconnectedtoadriveplate.Thedriveplate,orflexplateasitissometimesreferredto,isusedtoconnecttheconvertertothecrankshaftflywheelflangeoftheengine.Theringgear,whichthestartermotorengagestoturntheengine,isattachedtothedriveplate.TorqueConverterTransmitsenginetorquetothetransmissioninputshaft.Roleofthetorqueconverter:•Multipliestorquegeneratedbytheengine.•Servesasanautomaticclutchwhichtransmitsenginetorquetothetransmission.•Absorbstorsionalvibrationoftheengineanddrivetrain.•Smoothesoutenginerotation.•Drivestheoilpumpofthehydrauliccontrolsystem.Thetorqueconverterisfilledwithautomatictransmissionfluid,andtransmitstheenginetorquetothetransmission.Thetorqueconvertercaneithermultiplythetorquegeneratedbytheengineorfunctionasafluidcoupling.Thetorqueconverteralsoservesastheengineflywheeltosmoothoutenginerotationasitsinertiahelpstomaintaincrankshaftrotationbetweenpistonpowerpulses.Ittendstoabsorbtorsionvibrationfromtheengineanddrivetrainthroughthefluidmediumsincethereisnodirectmechanicalconnectionthroughtheconverter.Inaddition,therearhubofthetorqueconverterbodydrivesthetransmissionoilpump,providingavolumeoffluidtothehydraulicsystem.Thepumpturnsanytimetheenginerotates,whichisanSECTION28TOYOTATechnicalTrainingimportantconsiderationwhenavehicleistowed.Ifthevehicleistowedwiththedrivewheelsonthegroundandtheengineisnotrunning,theaxlesdrivethetransmissionoutputshaftandintermediateshaftonbearingsthatreceivenolubrication.Thereisagreatpotentialfordamageifthevehicleistowedforalongdistanceoratgreaterthanlowspeeds.Thetorqueconverter'sthreemajorcomponentsare;thepumpimpeller,turbinerunnerandthestator.Thepumpimpellerisfrequentlyreferredtoassimplytheimpellerandtheturbinerunnerisreferredtoastheturbine.Theimpellerisintegratedwiththetorqueconvertercase,andmanycurvedvanesthatareradiallymountedinside.Aguideringisinstalledontheinneredgesofthevanestoprovideapathforsmoothfluidflow.TorqueConverter-ImpellerThevanesofthestatorcatchthefluidasitleavestheturbineandredirectsitbacktotheimpeller.Whentheimpellerisdrivenbytheenginecrankshaft,thefluidintheimpellerrotateswithit.Whentheimpellerspeedincreases,centrifugalforcecausesthefluidtoflowoutwardtowardtheturbine.TorqueConverterComponentsPumpImpellerTORQUECONVERTERAutomaticTransmissions-Course2629Theturbineislocatedinsidetheconvertercasebutisnotconnectedtoit.Theinputshaftofthetransmissionisattachedbysplinestotheturbinehubwhentheconverterismountedtothetransmission.Manycuppedvanesareattachedtotheturbine.Thecurvatureofthevanesisoppositefromthatoftheimpellervanes.Thereforewhenthefluidisthrustfromtheimpeller,itiscaughtinthecuppedvanesoftheturbineandtorqueistransferredtothetransmissioninputshaft,turningitinthesamedirectionastheenginecrankshaft.TorqueConverter-TurbineFluidiscaughtinthecuppedvanesoftheturbineandtorqueistransferredtotheinputshaft.Beforemovingontothenextcomponentofthetorqueconverterweneedtoexaminethefluidcouplingwhosecomponentswehavejustdescribed.Whenautomatictransmissionsfirstcameonthesceneinthelate1930s,theonlycomponentsweretheimpellerandtheturbine.Thisprovidedameansoftransferringtorquefromtheenginetothetransmissionandalsoallowedthevehicletobestoppedingearwhiletheenginerunsatidle.However,thoseearlyfluidcouplingshadonethingincommon;accelerationwaspoor.Theenginewouldlaboruntilthevehiclepickedupspeed.Theproblemoccurredbecausethevanesontheimpellerandturbinearecurvedintheoppositedirectiontooneanother.Fluidcomingoffoftheturbineisthrustagainsttheimpellerinadirectionoppositetoenginerotation.Noticetheillustrationofthetorqueconverterstatoronthefollowingpage;thearrowdrawnwiththedashedlinesrepresentsthepathoffluidifthestatorwerenotthere,suchasinafluidcoupling.Notonlyisenginehorsepowerconsumedtopumpthefluidinitially,butnowitalsohastoovercometheforceofthefluidcomingfromtheturbine.Thestatorwasintroducedtothedesigntoovercomethecounterproductiveforceoffluidcomingfromtheturbineopposingenginerotation.Itnotonlyovercomestheproblembutalsohastheaddedbenefitofincreasingtorquetotheimpeller.TurbineRunnerFluidCouplingSECTION210TOYOTATechnicalTrainingThestatorislocatedbetweentheimpellerandtheturbine.Itismountedonthestatorreactionshaftwhichisfixedtothetransmissioncase.Thevanesofthestatorcatchthefluidasitleavestheturbinerunnerandredirectsitsothatitstrikesthebackofthevanesoftheimpeller,givingtheimpelleranaddedboostortorque.Thebenefitofthisaddedtorquecanbeasgreatas30%to50%.TorqueConverter-StatorThevanesofthestatorcatchthefluida