汽车专业英语课件-与汽车专业英语读译教程课件、参考译文18-U10TB

UNIT10BRAKINGSYSTEMSTEXTBTractionControlSystem(TRAC)andElectronicStabilityControl(ESC),PROFESSIONALENGLISH,UNIT3BRAKINGSYSTEMSTEXTBTractionControlSystem(TRAC)andElectronicStabilityControl(ESC)TractionControlSystem(TRAC)ComponentsTRACOperationIntakeElectronicStabilityControl(ESC)WhatIsElectronicStabilityControl?HowESCWorksManyNames,本次课学习内容,本次课学习目标,掌握TRAC和ESC系统的有关属术语掌握TRAC和ESC系统的组成和原理提高翻译技巧与阅读能力,NEWWORDS,PHRASESANDEXPRESSIONS,TractionControlSystem(TRAC)andElectronicStabilityControl(ESC)TractionControlSystem(TRAC)Thepurposeofthetractioncontrolsystem(TCS,orTRAC)(Fig.10-3)istopreventwheelspinfromoccurringduetoacceleration.Themaximumtorquethatcanbetransmittedtothewheelsisdeterminedbythecoefficientoffrictiongeneratedbetweentheroadandthetires.Iftorqueexceedsthatlevel,thewheelsarelikelytospin.ConditionsforTRACoperationmayinclude:loosegravel,slipperyroadsurfaces,accelerationwhilecorneringandhardacceleration1.Onceactivated,theTRACSystemreducesenginetorqueandrearwheelspeedasnecessarytobringthevehicleundercontrol.TheABSECU,TRACECUandECMallworktogethertoprovidetractioncontrol.ABSspeedsensorsaremonitoredbytheTRACECUwhichinturncontrolsasub-throttleplateandappliestherearbrakes.TheECMalsoretardsenginetimingwhiletheABSmodulatespressureattherearbrakes.,Fig.10-3TRACsystemcomponents,ComponentsTheTRACOFFswitchislocatedontheinstrumentpanelabovethecenterconsole.ItallowsthedrivertoactivateordeactivatetheTRACsystemwhentheswitchisdepressed.ThesystemdefaultstoONwhentheignitionswitchiscycled.TheTRACOFFindicatorlightgoesonwhenanyoneofthefollowingoccur:theTRACsystemisdeactivatedbytheTRACOFFswitch.aTRACrelatedproblemisdetectedwiththeengine.anABSrelatedproblemisdetected.TheTRACindicatorlightindicateswhen:thesystemisoperating.amalfunctionoccursinthesystem(itremainsilluminatedtowarnthedriver).thediagnosticmodeissetwithintheTRACECU(thelightblinksthetroublecode).,Sub-ThrottleValveMotorThesub-throttleactuatorusesastepmotorlocatedbetweenthemainthrottlevalveandaircleaner.Itisfittedonthethrottlebodyandcontrolsthepositionofthesub-throttlevalvebasedoncommandsmadebytheTRACECUthuscontrollingtheengineoutput.Bycontrollingthesub-throttleplate,enginemanagementcontrolsenginetorquereducingwheelspin.Sub-ThrottlePositionSensorThissensorisfittedtothesub-throttlevalveshaft.Itconvertsthesub-throttlevalveopeningangletoavoltagesignalandsendsthissignaltotheTRACECUviatheECM(EngineECU).Thesensoroperatesinthesamewayasthemainthrottlepositionsensor.TRACPumpThefunctionoftheTRACPumpistogeneratebrakefluidpressurenecessaryforapplyingthereardiscbrakeswhentheTRACsystemisoperating.Itdrawsbrakefluidfromthemastercylinderreservoir,pressurizesanddirectsittotheTRACbrakeactuator.,Fig.10-4Sub-throttlevalvemotor,TRACBrakeActuatorTheTRACbrakeactuatorconsistsoftwocutsolenoidvalvesandthreespringloadedvalveswhichregulatethebrakefluidpressureintherightandleftrearwheels.TherearwheelsarecontrolledindependentlythroughtheABSactuatorbasedonsignalsfromtheABSECU.ThemastercylindercutsolenoidvalveopensandclosesthehydrauliccircuitfromthemastercylinderorTRACpumptotheABSactuator.WhentheTRACsystemisoperating,itsuppliesthebrakefluidpressurefromtheTRACpumptothediscbrakecylindersviatheABSactuator.ItalsopreventsthefluidfromflowingoutoftheABSactuatorpumptothemastercylinder.ThereservoircutsolenoidvalveislocatedbetweenthereturnsideoftheABS3-positionsolenoidandthemastercylinder.Itreturnsthefluidfromthediscbrakecylindersbacktothemastercylinderreservoir.ThepressureregulatorvalvecontrolsthebrakefluidpressuregeneratedbytheTRACpump.,Thereliefvalverelievesthehighestsystempressureshouldamalfunctionoccur2.ThecheckvalvepreventsfluidfromflowingoutofthediscbrakecylindertotheTRACpump.TRACOperationDuringnormaloperation(TRACnotactivated)allsolenoidvalvesoftheTRACbrakeactuatorremaininactivewhenthebrakesareapplied.Asthebrakepedalisdepressed,brakefluidpressuregeneratedbythemastercylinderisappliedtothediscbrakecylinders,viathemastercylindercutsolenoidvalve,andthe3-positionsolenoidvalvesintheABSactuator.Whenthebrakepedalisreleased,fluidpressurereturnsfromthediscbrakecylinderstothemastercylinder.Duringvehicleacceleration(TRACoperative)whenarearwheelslipstheTRACsystemcontrolstheengineoutputandbrakingoftherearwheelstohelppreventwheelslippage.,Thebrakefluidpressureappliedtotherightandleftrearwheelsiscontrolledseparatelyaccordingto3controlmodes:pressureincrease,pressureholdingandpressurereduction.PressureIncreaseModeWhenarearwheelstartstoslip,justastheacceleratorpedalisbeingdepressed:AllthesolenoidvalvesintheTRACbrakeactuatorareactivatedbysignalsreceivedfromtheABSECU.The3-positionsolenoidvalvesintheABSactuatorareengagedinthepressureincreasemode(Fig.10-5).Themastercylindercutsolenoidvalveisactivated(portsAandCopen),andbrakefluidpressuregeneratedbytheTRACpumpisappliedtothediscbrakecylindersviathemastercylindercutsolenoidvalveandthe3-positionsolenoidvalvesintheABSactuator.Thereservoircutsolenoidvalveisalsoactivated(open)allowingfluidtoflowbacktothemastercylinderreservoir.TheTRACpumpdischargepressureismaintainedconstantbythepressureregulatorvalve.,Fig.10-5Pressureincreasemode,PressureHoldingModeWhenthebrakefluidpressurefortherearbrakecylindersisincreasedordecreasedasrequired,thesystemswitchestotheholdingmode.Thismodechangeisperformedbyengagingthe3-positionsolenoidvalveintheABSactuatortotheholdingmode.ThisresultsinblockingtheTRACpumppressurefromflowingtothediscbrakecylinderthroughportD.PressureReductionModeWhendecreasingpressureappliedtotherearbrakecylinders,theABSECUengagesthe3-positionsolenoidvalveintheABSactuatortothepressurereductionmode.Fluidpressureappliedtothebrakecylinderreturnstothemastercylinderreservoirfromthe3-positionsolenoidvalveandreservoirintheABSactuatortothereservoircutsolenoidvalve,thusalleviatingthebrakefluidpressure.,WheelSpeedControlTheTRACECUconstantlyreceivessignalsfromthe4speedsensorsandcalculatesthespeedofeachwheel.Atthesametime,itestimatesthevehiclespeedbasedonthespeedofthe2frontwheelsandsetsatargetcontrolspeed.Whentheacceleratorpedalisdepressedonaslipperyroad,therearwheels(drivingwheels)begintoslipandtherearwheelspeedexceedsthetargetcontrolspeed.TheTRACECUthensendsaclosesignaltothesub-throttlevalvemotor.Atthesametime,ABSECUsendsasignaltotheTRACbrakeactuatorandcausesittosupplybrakefluidpressuretoreardiscbrakecylinders,changingthereardiscbrakesintheTRACmode.The3-positionsolenoidvalvesoftheABSactuatoraremodulatedtocontrolrearbrakefluidpressuretopreventwheelslippage.,ElectronicStabilityControl(ESC)Automotivesafetyhastakencenterstage,especiallyasSUVshavemadetheheadlinesfortheirtendencytorollover.Fortodaysconsumers,however,electronicstabilitycontrol(ESC)canmakeadifference.ESCcansignificantlyreducetheriskofanSUVrollover.WhatIsElectronicStabilityControl?ESCisanactivesafetysystemthatusessensorstodetectwhenadriverisabouttolosecontrolofthevehicleandautomaticallyintervenestoprovidestabilityandhelpthedriverstayontheintendedcourse,especiallyinoversteeringandundersteeringsituations.Industryexpertshavehailedelectronicstabilitycontrolasamilestoneinautomotivesafety,comparingittoseatbeltsandairbags.ESCkeepsvehiclesontheroad,helpspreventrolloversandskids,andisthustheeasysafetychoiceforconsumerswhenpurchasinganewvehicle.,AnumberofstudieshavebeenconductedtestingtheeffectivenessofESC,andtheglobalautosafetyresearchverifiesthatelectronicstabilitycontroldoes,infact,savelives.Fivedifferentstudiesprojecteda30-35%reductioninsinglevehiclecrashesthankstoESC.HowESCWorksItincorporatesanti-lockbrakes(ABS)andtractioncontrol(TCS),whichpreventwheellockwhenbrakingandwheelspinwhenaccelerating,andgoesastepbeyondbothsystems,actingwhenlateralforcesareatworktofurtherreducetheriskofskiddinginalldrivingsituations.ESCconstantlycomparesthedriversintentionwiththevehiclesactualbehaviorbymonitoringwheelspeeds,steeringwheelangle,yaw-rate,lateralacceleration,throttlepositionandmastercylinderpressure.Acentralmicrocomputeranalyzestheincomingdata.Wheninstabilityisdetected,ESCimmediatelytriggersaresponsetokeepthevehicleoncourse,automaticallybrakinganyofthefourwheelsand/oradjustingenginetorque.ESCisofferedasoptionalorstandardequipmentinawidevarietyofvehiclesfromnearlyeve