机械类数控外文翻译外文文献英文文献黏性连接器

1、1TheEffectofaViscousCouplingUsedasaFront-WheelDriveLimited-SlipDifferentialonVehicleTractionandHandling1ABCTRACTTheviscouscouplingisknownmainlyasadrivelinecomponentinfourwheeldrivevehicles.Developmentsinrecentyears,however,pointtowardtheprobabilitythatthisdevicewillbecomeamajorplayerinmainstreamfront-wheeldriveapplication.ProductionapplicationinEuropeanandJapanesefront-wheeldrivecarshavedemonstratedthatviscouscouplingsprovidesubstantialimprovementsnotonlyintractiononslipperysurfacesbutalsoinhan。

2、dingandstabilityevenundernormaldrivingconditions.Thispaperpresentsaseriousofprovinggroundtestswhichinvestigatetheeffectsofaviscouscouplinginafront-wheeldrivevehicleontractionandhanding.Testingdemonstratessubstantialtractionimprovementswhileonlyslightlyinfluencingsteeringtorque.Factorsaffectingthissteeringtorqueinfront-wheeldrivevehiclesduringstraightlinedrivingaredescribed.Keyvehicledesignparametersareidentifiedwhichgreatlyinfluencethecompatibilityoflimited-slipdifferentialsinfront-wheeldriveveh。

3、icles.Corneringtestsshowtheinfluenceoftheviscouscouplingontheselfsteeringbehaviorofafront-wheeldrivevehicle.Furthertestingdemonstratesthatavehiclewithaviscouslimited-slipdifferentialexhibitsanimprovedstabilityunderaccelerationandthrottle-offmaneuversduringcornering.2THEVISCOUSCOUPLINGTheviscouscouplingisawellknowncomponentindrivetrains.Inthispaperonlyashortsummaryofitsbasicfunctionandprincipleshallbegiven.Theviscouscouplingoperatesaccordingtotheprincipleoffluidfriction,andisthusdependentonspeedd。

4、ifference.AsshowninFigure1theviscouscouplinghasslipcontrollingpropertiesincontrasttotorquesensingsystems.Thismeansthatthedrivetorquewhichistransmittedtothefrontwheelsisautomaticallycontrolledinthesenseofanoptimizedtorquedistribution.Inafront-wheeldrivevehicletheviscouscouplingcanbeinstalledinsidethedifferentialorexternallyonanintermediateshaft.TheexternalsolutionisshowninFigure2.Thislayouthassomesignificantadvantagesovertheinternalsolution.First,thereisusuallyenoughspaceavailableintheareaofthein。

5、termediateshafttoprovidetherequiredviscouscharacteristic.Thisisincontrasttothelimitedspaceleftintoday’sfront-axledifferentials.Further,onlyminimalmodificationtothedifferentialcarrierandtransmissioncaseisrequired.In-houseproductionofdifferentialsisthusonlyslightlyaffected.Introductionasanoptioncanbemadeeasilyespeciallywhentheshaftandtheviscousunitissuppliedasacompleteunit.Finally,theintermediateshaftmakesitpossibletoprovideforsideshaftsofequallengthwithtransverselyinstalledengineswhichisimportant。

6、toreducetorquesteer(shownlaterinsection4).Thisspecialdesignalsogivesagoodpossibilityforsignificantweightandcostreductionsoftheviscousunit.GKNViscodriveisdevelopingalowweightandcostviscouscoupling.Byusingonlytwostandardizedouterdiameters,standardizedplates,plastichubsandextrudedmaterialforthehousingwhichcaneasilybecuttodifferentlengths,itispossibletoutilizeawiderangeofviscouscharacteristics.AnexampleofthisdevelopmentisshowninFigure3.3TRACTIONEFFECTSAsatorquebalancingdevice,anopendifferentialprovi。

7、desequaltractiveefforttobothdrivingwheels.Itallowseachwheeltorotateatdifferentspeedsduringcorneringwithouttorsionalwind-up.Thesecharacteristics,however,canbedisadvantageouswhenadhesionvariationsbetweentheleftandrightsidesoftheroadsurface(split-μ)limitsthetorquetransmittedforbothwheelstothatwhichcanbesupportedbythelow-μwheel.Withaviscouslimited-slipdifferential,itispossibletoutilizethehigheradhesionpotentialofthewheelonthehigh-μsurface.ThisisschematicallyshowninFigure4.Whenforexample,themaximumtr。

8、ansmittabletorqueforonewheelisexceededonasplit-μsurfaceorduringcorneringwithhighlateralacceleration,aspeeddifferencebetweenthetwodrivingwheelsoccurs.Theresultingself-lockingtorqueintheviscouscouplingresistsanyfurtherincreaseinspeeddifferenceandtransmitstheappropriatetorquetothewheelwiththebettertractionpotential.ItcanbeseeninFigure4thatthedifferenceinthetractiveforcesresultsinayawingmomentwhichtriestoturnthevehicleintothelow-μside,Tokeepthevehicleinastraightlinethedriverhastocompensatethiswithop。

9、positesteeringinput.Thoughthefluid-frictionprincipleoftheviscouscouplingandtheresultingsofttransitionfromopentolockingaction,thisiseasilypossible,Theappropriateresults2obtainedfromvehicletestsareshowninFigure5.Reportedaretheaveragesteering-wheeltorqueTsandtheaveragecorrectiveoppositesteeringinputrequiredtomaintainastraightcourseduringaccelerationonasplit-μtrackwithanopenandaviscousdifferential.Thedifferencesbetweenthevalueswiththeopendifferentialandthosewiththeviscouscouplingarerelativelylargein。

10、comparisontoeachother.However,theyaresmallinabsoluteterms.Subjectively,thesteeringinfluenceisnearlyunnoticeable.Thetorquesteerisalsoinfluencedbyseveralkinematicparameterswhichwillbeexplainedinthenextsectionofthispaper.4FACTORSAFFECTINGSTEERINGTORQUEAsshowninFigure6thetractiveforcesleadtoanincreaseinthetoe-inresponseperwheel.Fordifferingtractiveforces,Whichappearwhenacceleratingonsplit-μwithlimited-slipdifferentials,thetoe-inresponsechangesperwheelarealsodifferent.Unfortunately,thiseffectleadstoan。