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外文翻译--6档自动变速器和CVT 对燃油经济性的贡献.doc外文翻译--6档自动变速器和CVT 对燃油经济性的贡献.doc -- 5 元

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SixSpeedAutomaticTransmissionsandCVT′stoSupportFuelEconomyAbstractTheimprovementinfueleconomyandinCO2emissionlevelshasahighpriorityinthedevelopmentworkofnewpassengercarsandnewmodels.Newlydeveloped6speedautomatictransmissionsandcontinuouslyvariabletransmissionsCVTwillbeavailableinvehiclesinthenearfuture.Thesetransmissionswillfulfilltherequirementstoreducefuelconsumptionandemissionsandwillincreasedrivingcomfortatthesametime.Acomparisonwiththestateoftheartsolutions,i.e.5speedautomatictransmissionsforrearwheeldrivenand4speedautomaticsforfrontwheeldrivencars,showstheadvantageofthenewtransmissionsystems.ThenewdesignsleadtoafuelconsumptionreductionintheNewEuropeanDrivingCycleNEDCof6to8.Inparallelthereisanincreaseinaccelerationfrom0to60mphof4to10.1IntroductionCurrentlyinpassengercardevelopment,areductioninfuelconsumptionisoneofthekeycriteriathatanewvehicleoranewmodelismeasuredfor.InEurope,themotivatingforcebehindthisisthe1991self2adoptedmissionofGermanautomotivemanufacturerstoreducefuelconsumptionby25bytheyear2005andtheproposalsentbytheAassociationofEuropeanAutomotiveIndustryACEAtotheEuropeanComm.issionin1995callingforareductionoffleetconsumptionforthevehicleslicensedinEurope.Theself2adoptedmissionofGermanautomotivemanufacturersVDAconsentpredict,onaveragefortheindustry,areductioninaverageconsumptionfrom8l/100kmto6l/100kmoveraperiodof14years.Thiscorrespondstoanincreasefrom56.8mpgto75.7mpg.TheACEAagreementisbasedonareductioninCO2emissionsfrom180g/km112g/mito140g/km87g/mIbytheyear2008.Thisisanextremelyambitioustargetachievedonlythroughagreatnumberofimprovementmeasures.Inadditiontoimprovementsontheengine,thedrivelinealsohastocontributetowardstheattainmentofthisobjective.Thetransmission,asthemainunitinthedriveline,isofparticularimportance.Whencallingforareductioninfuelconsumption,othercriteriademandedofthedrivelinemustbetakenintoconsideration.Inparticular,performanceshouldbementionedhere.Fuelreductionandperformanceoptimaisationrepresentconflictingobjectivesfordrivelinedevelopmentsandaretypicalofmanytechnicaltasks.Anappropriatecompromisemustbefoundfortheindividualapplications.Inadditiontomminimumfuelconsumptionandgoodperformancevalues,drivecomfortalsoplaysanincreasinglyimportantroleasanevaluationcriterionforassessingpassengercars.WwithinEurope,thisisalsoresultinginanincreasingproportionofautomatictransmissionsseeFigure1.Duetothesettingofelementsfittedasstandardinautomatictransmissions,thehydrodynamictorqueconverter,oilpump,hydraulicunitanddraglossesinshiftelementsresultinautomatictransmissionsexperiencinghigherlevelsofpowerlossescomparedtomanualtransmissions.Satisfyingtherequirementsoffuelreductionisthereforeaparticularlydifficultchallengewhencombinedwwithanincreaseintheuseofautomatictransmissions.Inordertoavoidthesystemrelateddisadvantagesofclassicmultiratioautomatictransmissions,continuouslyvariabletransmissionarenowavailableonthemarket.Othertransmissionsystems,primarilybasedonmanualtransmissionconcepts,arecurrentlyunderdevelopment.Fig.1DevelopmentoftheautomatictransmissionspenetrationinpassengercarsinWesternEuropeSincedifferenttransmissionsystemsareappropriatefordifferentapplicationsinpassengercars,ageneralcomparisonofhowthetransmissionimpactsfuelconsumptionisoflimiteduse.Thispaperwillnotprovidedetailsofhowallthenamedsystemsimpactfuelconsumption,butitwillconsiderthepotentialforimprovingfuelconsumptionforselectedtransmissionsystems.Thepaperwillfocusonsystems,whicharebeinglaunchedasvolumeproductionmodels.Afewcommentsregardingthe5and62speedmanualtransmissionswillbefollowedbyareviewofthe5and6speedautomatictransmissionsforstandarddrivelines.The4,5and6speedautomatictransmissionsandcontinuouslyvariabletransmissionsusedinfrontwheeldriveFWDvehicleswillalsobereviewed.2FuelsavingsandperformanceTheEuropeanECEdrivingcycleconsistsofonethirdurbantravelandtwothirdsconstanttravelat90and120km/hrespectivelyandhasbeenusedasabasisforcomparingfuelconsumptionformanyyearsinEurope.CurrentlytheNewEuropeanDrivingCycleNEDCNEFZNeueEuropaischeFahrzyklusorMVEGMotorVehicleEmissionsGroupforvehiclesofupto2.5tonsdefinesthebasisforevaluatingfuelconsumptionandexhaustemissionsseeFigure2.Thisoveralldrivingcycleillcharacterizethebasisforcomparisonsinthispaperwhenevaluatingtransmissionsystems.Usageinothercountriesillbebasedonotherdrivingcycles,forexample,theEPAintheUS.Simsearly,differentautomotivemanufacturersandtestinstitutionsusespecifictestprocedures,whichwillnotbeconsideredhere.Consumptioncomparisonsarerepresentedintheformofabsolutevaluesinlitersper100kmormilespergallonmpgand/orasrelativedeviationsin,wheretransmissionsrepresentingpreviousstate2of2the2arttechnologyserveatthebasisforcomparison.Takeoffaccelerationdistancereachedafter4seconds,fullloadaccelerationtimetoreach100km/hor60mphfrom0km/handelasticitytimetakentoincreasefrom80to120km/h,whichrepresentimportantparametersinthecustomersevaluationofavehicletodayhavebeenestablishedastheassessmentcriteriaforperformance.Assessmentsmadeinthispaperwillfocusonfullloadacceleration,whichwillbespecifiedastimeinseconds.Fig.2EuropeandrivingcycleNEDCTheconsumption2acceleration2diagramseeFigure6isatooltodescribeconsumptionandperformanceinonediagram.Basedonfullthrottleacceleration,thisdepictsthefuelconsumptionofavehiclewithoneparticularengineanddifferenttransmissions.Anotherparameteristheaxleratiowhichinfluencesfuelconsumptionandacceleration.Theconsumptionaccelerationdiagramwillvaryif,forexample,mpgmilespergallonisappliedtotheconsumptionaxisinsteadofl/100kmlitresper100kilometresorifthesettingofaccelerationasdistanceafter4secondsisusedastheperformanceparameter.Theaxleratioparametercanalsobemodifiedbyotherinfluencingparameterssuchasvehicleweight.Theconsumptionandaccelerationvaluesshowninthispaperaremainlybasedonsimulationcalculations.Inthesimulationmodel,thelossesofdifferenttransmissionsystemsasmeasuredvaluesfromtransmissiontestsaretakenintoconsiderationsotheinfluenceofthetransmissionisdepictedrealistically.Inordertoissueastatementregardingtheaccuracyofthesimulationresults,someofthecalculatedresultswerecomparedwitthemeasuredvalues.Thisshowedtheabsolutevaluesarenotalwayscalculatedpreciselyduringsimulationbutthecomparativevaluescorrelateverywell.Arelativecomparativereviewwillprovideaccuratestatements.3TransmissionconceptsInthepast,4and5speedmanualtransmissionsMTwerethemaintransmissionsfoundontheEuropeanmarket.Thankstotheirmechanicalstructure,theyareefficientbutasaresultofincreasedtrafficandgreateremphasisoncomfort,theynolongersatisfytherequirementsofmanycustomers.Therefore4and5speedautomatictransmissionsATarealsoused.Currentlytheseofferaveryhighlevelofdrivecomfort,buthavethedisadvantageofhigherpowerlossesandgenerallyresultinhigherfuelconsumption.Inadditiontothisandalongsidethetwoclassictransmissionsystemsmanualandmultiratioautomatictransmissions,thereareothertransmissionsystemsonthemarketandunderdevelopment,whichthemainobjectiveistocontributetowardsareductioninfuelconsumptionforpassengercars.Manualtransmissionsareexperiencingatrendtowards6gears,shiftandclutchautomation.ThisresultsinautomatedmanualtransmissionsAMT.UsinghydraulicallyorelectromechanicallyactuatedAMTsystems,whicharebasedonthemechanicsofmanualtransmissions,shiftscanbeimplementedusingtheautomaticcontrolofashiftprogram.Apowershiftprocesscharacterizesshiftsinautomatictransmissionsystemswithnointerruptiontotraction.In2001thefirst6speedautomatictransmissionwasintroducedinthemarket.Inadditionto62speedautomatictransmissions,therearealsocontinuouslyvariabletransmissionsCVTonthemarketwithpushbeltsandchainsservingasthetorquetransmittingelementandcontinuouslyvariabletoroidaldriveswhicharedevelopedasrollertypetransmissions.Dualclutchtransmissionsbasedonmanualtransmissionsareunderdevelopment.Sincepowershiftscanbeimplementedwiththesesystems,theyshouldbeclassifiedasautomatictransmissions.Aspreviouslymentioned,thefollowingcomparisonoffuelconsumptionanddrivingperformanceislimitedtotransmissionsystemswhicharebeinglaunchedasvolumeproductionmodelsorwillbeavailableonthemarketinthenearfuture.ForstandarddrivelineconfigurationswiththeengineinstalledlongitudinallyatthefrontandwithrearwheeldriveRWD,6speedmanualtransmissionswillbeincreasinglyu2sedfortheuppertorquerange.Section4brieflydealswithhowthisimpactsfuelconsumptionandacceleration.AtransitionwillalsotakeplaceinEuropefromthecurrentstandard5speedto6speedtransmissionsinRWDvehicles.Figure3showsaschematiccomparisonofa5speedanda6speedautomatictransmission.TheZFtransmissions,5HP24and6HP26,arecomparedinSection5.Sinceitisexpectedthatcontinuouslyvariabletransmissionswillgainincreasedmarketshareforfront2wheeldriveFWDvehicleswiththeenginearrangedtransverselyatthefrontofthevehicle,acomparisonbetween4,5and6speedautomatictransmissionsandaCVTContinuouslyVariableTransmissionhasbeendevelopedforthisdrivelineconfiguration.Figure4showsaschematiccomparisonbetweena5speedautomatictransmissionandthecontinuouslyvariabletransmissionZFCFT23.
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