SAETECHNICAL PAPERSERIES 981097 Prediction ofTorqueResponse Duringthe Engagement ofWetFrictionClutch YuboYangandRobertC.Lam Borg-Warner Automotive TamotSLiFujii NSK-Warner Reprinted From:1998Transmission andDrivelineSystemsSymposium: NewDevelopments andAdvancedConcepts inSystemsandComponents (SP-1324) International CongressandExposition Detroit,Michigan February23-26,1998 400Commonwealth Drive,Warrendale, PA15096-0001 U.S.A.Tel:(724)776-4841 Fax:(724)776-5760 Downloaded from SAE International by Birmingham City Univ, Sunday, August 19, 2018Theappearance oftheISSNcodeatthebottomofthispageindicatesSAE'sconsentthat copiesof thepapermaybe madeforpersonalorinternaluseofspecificclients.Thisconsent isgivenontheconditionhowever,thatthecopierpaya$7.00perarticlecopyfeethrough theCopyrightClearanceCenter,Inc.OperationsCenter,222Rosewood Drive,Danvers, MA01923forcopyingbeyondthat permittedby Sections107or108oftheU.S.Copyright Law.Thisconsentdoes notextendtootherkindsofcopyingsuchascopyingforgeneral distribution, foradvertisingor promotionalpurposes, forcreatingnew collective works,or forresale. SAEroutinelystocksprintedpapersforaperiodofthreeyearsfollowingdate ofpublication. Directyourordersto SAECustomerSales andSatisfaction Department. QuantityreprintratescanbeobtainedfromtheCustomerSalesandSatisfaction Depart ment. Torequestpermission toreprinta technicalpaperor permissiontousecopyrightedSAE publications inother works, contacttheSAE PublicationsGroup. Nopartofthispublication maybyreproduced inanyform,inanelectronicretrievals/stem orotherwise,withoutthepriorwritten permissionofthepublisher. ISSN0148-7191 Copyright 1998SocietyofAutomotive Engineers, Inc. Positionsandopinionsadvancedinthis paperarethoseoftheauthor(s)andnotnecessarily thoseofSAE.Theauthorissolelyresponsibleforthe contentofthe paper.A processis availablebywhichdiscussions willbeprintedwiththepaperifitispublishedinSAE Transactions. Forpermission topublishthispaperinfullorinpart,contacttheSAE Publications Group. Personswishingtosubmitpaperstobeconsideredforpresentation orpublicationthrough SAEshouldsendthemanuscript ora300wordabstractofaproposedmanuscript to: Secretary,Engineering MeetingsBoard,SAE. PrintedinUSA90-1203B/PG Downloaded from SAE International by Birmingham City Univ, Sunday, August 19, 2018981097 Prediction ofTorqueResponse Duringthe Engagement ofWetFrictionClutch YuboYangtandRobertC.Lam Borg-WarnerAutomotive TamotsuFujii NSK-Warner ©Copyright 1998SocietyofAutomotive Engineers, Inc. Abstract Theapproximate torqueresponsemodelforthe engagement ofawetfrictionclutch,developed by Berger[1,2],wasmodifiedandenhanced.Themod ifiedReynoldsequationforthefilmthicknessand forcebalanceforthewetclutchpackaresolvednu merically. TheReynoldsequationrelatesthefilm hydrodynamic pressuretothefilmthickness,phys icalproperties offrictionmaterials, andoperating parameters. Thetorqueiscalculatedfromthefilm andasperitypressuredistribution atthefrictionin terface.Theappliedpressureandtheinterfacetem peratureasafunctionoftimeduringengagement areconsidered inthemodel.Thecorrectaverage flowfactorsofPatirandCheng[3,4]forATFflow betweenroughsurfacesareincorporated intothe model.Thepermeability offrictionmaterialsand thetemperature gradientinsidethefrictionmaterial areconsidered. Thekeyinputparameter forpredicting the torqueresponseisthefrictioncoefficient asafunc tionofslidingspeed,temperature, andpressure, whichcanbemeasuredbytheLowVelocityFriction Apparatus (LVFA).Theeffectsofphysicalandoper atingparameters onthetorqueresponsearedemon strated.Finally,themodelpredictions ofthetorque responsearecompared favorably withtheexperi mentalmeasurements undervariousoperatingcon ditions.Introduction Thewetfrictionclutchusedinautomatic trans- missionsconsistsofmultipleseparators andfriction plates.Thekeyelementintheclutchpackisthe frictionplate,madeofalowcarbonsteelwithfric- tionmaterialsbondedoneachside.Atypicalclutch packcontainsmultipleseparatorplatesandfriction plates.Thefrictionplatesaresplinedtot