商用车辆传动系统的概念变速器对燃油消耗噪声和舒适性的影响情况外文翻译本科学位论文.docx
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商用车辆传动系统的概念变速器对燃油消耗噪声和舒适性的影响情况外文翻译本科学位论文.docx
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商用车辆传动系统的概念变速器对燃油消耗噪声和舒适性的影响情况外文翻译本科学位论文
ConceptsforCommercialvehicleDriveTrains——InfluenceofTransmissiononConsumption,NoiseLevelandComfort
[Abstract]Thetransmissionhasaconsiderableinfluenceonfuelconsumptionnoiselevelandcomfortwithinthevehicledrivetrain.TheselectedexamplestakenfromtheZFproductrangshowseveraltransmissiontypesintypicalvehicleapplications.Thepowerweightratioofcurrenttransmissionswasconsiderablyimprovedinallareasincomparisonwithpreviousversions.Improvementsconcerningnoiselevelsanddemandsforhighercomforthavebecomeevenmoreimportant.Theforefullyautomatictransmissionswillachievealargershareofthemarket.Inthefuture,alternativedrivetrainconceptssuchaselectricwheeldrivesusedincitybuseswillenhancethedrivetrainproductrange.
Keywords:
CommercialvehicleTransmissionFuelconsumptionNoiselevelComfort
Introduction
Fourimportantaspectswilldeterminecommercialvehiclesofthefuture:
·Legislation(exhaustgasese/noise/accidentPrevention)
·Differentcustomerrequirements(numberOfvariants)
·Globalizationofproductionandsales
·Technologies,inparticulartransmissiontechnology
InadditiontothekeyenginedevelopmentswiththeobjectiveofsatisfyingtheexhaustgasstandardsdefinedinEUEuroandEUEuroIV,theoptmiumconfigurationofthedrivetrainisof→Dieselenginesremainpredominant
●Widerconsumptioncharacteristicscurves
●Torquelevelsofupto3000Nminthefuture
→Comfortrequirementsasinpassengercar
●Reductionandharmonizationofshiftforces
●Increased:
automatictransmissionswithoptimumadaptiontothecombustonengine
●Minmiizationoffuelconsumption,emissions
●Reductioninnumberofgearsfrom16to12orless→Electricaldrivetechnologyincitybuses
●Alternativestomechanicaldrivetrain
●Hybridconcepts,batteryrunbuses
●Fuelcellvehiclesatteststageendsincommercialenginesdecisiveimportancehere.
Thefollowingtrendsarethereforeindicatingthefuturefornewcommercialvehcledevelopmentsonthedrivetrain:
·Individualisationwithfullutilizationofthemodularsystem
·Economicviabilitythroughuseoflightconstruction,drivetrainoptimizationandimprovedefficiencyaswellasreductioninmaintenancecosts
·Environmentalcompatibilitythroughuseofconservationofresourcesandextensiverecyclingoptionsforallmaterialsused
·Electricalandelectronicunitsusedmoreinalldrivetrainareas
·SafetyoptmiizationmeasuresthroughtheuseofsystemsolutionsincorporatingallkeyactiveelementssuchasABS,ESPandtotaldrivetrainfeedbackcontrolandbrakemanagement,includingtheuseofretarders.
Severalexampleswillnowbeusedtodemonstratethetransmission’sinfluenceoncostsavings,fuelconsumption,noiselevelsandcomfortwithintheoveralldrivetrain.Thiswillthenbesupplementedbyapredictionoffuturedevelopmentsforthedrivetrain.
Drivetrainconfiguration
Thebasicversionofacommercitrainwithdieselengine(withdirectfuelinjection),multigearedtransmissionandsingleordoubleratiodriveaxleshasnotchangedinthepastfewdecades.
Asfarastheengineisconcerned,thedieselenginewillremainthemainsourceofdriveintheforeseeablefutureduetoitsmanyadvantages(including:
gooduseofprimaryenergy,highpowerweightratiofortheengineandfuelaccumulator,highlevelofreliability)
.Anextensionofthefuelconsumptioncharacteristicscurvesgoeshandinhandwithafarreachingincreaseinthemaximumenginetorque.
Themainoperatingrangeoftheenginesusedforheavydutytrucksiscurrentlyattorquelevelsof1500-2000Nm,itishoweverexpectedthatengineswillhavetorquelevelsof3000Nmintheforeseeablefuture(Fig.1).Themiminizationoffuelconsumptionandareductionofemissionswillrepresentakeytaskinenginedevelopmentinthenearfuture.
Significanceofthetransmission
Inadditiontothedevelopmentsindicatedwithregardtotheengine,thetransmissionmusthoweverbeviewedasthesecond,essentialelementofthedrivetrain.Aharmoniousbeing,whichcanhandlealldrivesituations,canonlybecreatedthroughinteractionofthesetwounits.
Thetransmissionmustsatisfythefollowingrequirementsifitistobeanadequatepartnerfortheengine:
·simpleoperation
·fewlosses
·compactdimensions
·lowweight
·highlevelsofreliability
·servicelife
·lowcosts
Thetransmissionshaveasignificantinfluenceonthevehiclecharacteristics.OneglanceatFig.2indicatesthegreatnumberofrequirementsplacedonthetransmissioin.Ifyoulookatthedifferentassessmentcriteriaforroadvehicles,itbecomesclearthatallsystemsproduced,includingthealvehicledrivehedrivetrainisoftransmissionarecertainlyalwaysdepictedwithaweightedoptimizationbecausesomecriteriarequireconflictingsolutions.
Incomparisontopassengercars,theabsolutepriorityforcommercialvehiclesistoearnmoney.
Asaverygeneralrule,youcansaythattherequirementsofmodernvehiclesareincreasingandthatcomfortrequirementsaredirectingthemselvesmoreandmoretowardsthestandardsusuallyappliedincars.
Commercialvehicleshaveverydifferenttasksandareasofapplication(Fig.3).Whenconsideringbuses,cityandlinebusesshouldbementionedontheonehandasshould(long-distance)coachesontheotherhand.Theareaofapplicationfortrucksextendsfromthelight-dutyclass(localdeliverytrucks)throughmedium-dutyclassestoheavy-dutylong-distancehaulagetrucks.Constructioinsiteandspecialvehiclesorevenmunicipalvehiclescanalsobeaddedtothislist.Whenallthesetypesofapplicationarecombinedwiththeengineratinginstalledandthespecialcustomerrequests,theycharacterizetherequirementsplacedonthetranSmission.
AnumberoftranSmissionvariantsarecurrentlyavailableforroadvehicles.
AccordingtoFig.4,aninitialdistinctioncanbemadebetweenmultiratiotransmissionsandcontinuouslyvariabletransmissions.Whendealingwithmultiratiotransmissions,oneshouldconsiderthegroupofmanuallyshiftedtransmissionswithconstantmesh,synchromeshorservoshiftsystemaswellasthegroupofautomatictransmissions,whereadistinctionismadebetweenpowershiftautomaticunitsandautomatedshiftunits.Thecontinuouslyvariabletransmissionsextendfrommechanicallycontinuouslyvariabletransmissions(chain/beltand/ortoraidaltransmissions)throughhydrostaticunitstoelectricaldrivetrainswithvariouscharacteristics.Anadditionaldistinctioncanbemadewithmutli-ratiotransmissionsastothetypeofshiftsystem,wheregearshiftsareeitherundertakenwithorwithoutaninterruptiontotraction.
Allcontinuouslyvariabletransmissionshaveonecommonfeature:
theratiocanbeadjuwithoutanynoticeableinterruptiontotraction.
Therequirementsplacedonthetransmissioninthevariousareasofapplicatioindiffergreatly.Adifferentiatedprioritizationofcriteria(refertoFig.2)therebyresultsinanindividualpreferenceforcertaintransmissionstypesintheindividualsegments.Onthewhole,youcansaythatasinthepast,manualtransmissionscontinuetodominateintruckswhereemphasisisplacedoncostsavings,fuelconsumptionandefficiencyratherthancomfort.Ininstanceswherecomfortplaysadecisiverole,suchasincitybuseswithfrequentstoppingandstartingoperations,preferenceisgiventopowershiftautomatictransmissions.Fullyautomatictransmissions,whichstemfrommanualtransmissions,attempttocombinetheadvantagesoffavourableefficiencywithasatisfactorydegreeofshiftingcomfort.
Therequirementforcomfortandeasyeroperationishowevercurrentlybecomingincreasinglyimportant(refertoFig.1).Asfarasthetransmissionisconcerned,thismeansbothareductionandharmonizationofshiftforcesinmanuallyshiftedtransmissionaswellasanincreasinginterestinautomatedtransmissionswithinthedrivetrainwithanoptimumadaptationtothecombustionengine.
Furthermore,areductioninthenumberofgears(from16to12or10gears)canalsobeseen,inparticularindrivetrainconceptswithenginemanagement.
Whereaselectricaldriveconceptsremainthepreferredoptioninallspecialapplicationsintrucks,importantactivitiesshouldbenotedinthebusfield,especiallywithregardtocitybuses.Thegenerallyintroducedlowfloortechnologyisnotthesoleinitiatorofthisdevelopment.Theworkconsistsoffindingalternativestothestandardmechanicaldrivetrainbymeansofacharacteristicscurveoptimizedmethodofoperatingthedieselengineusinghybridconcepts.Furthermore,alternativesourcesofenergysuchasbatteries,catenarywireoperation,butalsofuelcellsarealsoalreadybeingtested.
Thefollwinginformationusesselectedexamplestoindicatetheextenttowhichthesvariousapproachesaffectfuelconsumption,noiselevelandcomfort.
Fuelconsumption
Thegeneralformulaforcalculatingthefuelconsumptioniswellknownfromanalysisofthelognitudinaldynamicsofroadvehiclestakingintoaccountthedifferentlevelsofdriveresistanceandengineand/ordrivetraincharacteristics:
Thetransmissionwithinthedrivetraindirectlyandindirectlyinfluencesthefuelconsumptionvia
·vehiclemassm
·transferefficiencyofthedrivetrainη
·specificfuelconsumptionbe(refertoFig.5)
Measuresundertakenonthetransmissionincludeweightreduction,improvedefficiencyandassistanceintheoptimumrecordingofthefuelcharacteristicscurve.
Inviewofthefactthatthetransmissionmakesuparelativelylowproportionofthetotalvehiclemass,measurestoreduceweightcanofcourseonlyimprovetheoverallsituatio
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