~.AeTheEngineering Society~ ForAdvancing Mobility~ LandSeaAirandSpace® 400COMMONWEALTH DRIVEWARRENDALE, PA15096 880481 The"ECVT"ElectroContinuously Variable Transmission Yasuhito Sakai FujiHeavyIndustries Ltd. International CongressandExposition Detroit.Michigan February29-March4.1988Downloaded from SAE International by ETH Bibliothek Zurich, Wednesday, March 08, 2017Theappearance 01thecodeatthebottomofthefirstpageofthispaperindicates SAE'sconsentthatcopiesofthepapermaybemadeforpersona! orintern;:lU5e,or forthepersonal orinternaluseofspecificclients.Thisconsentisgivenonthecon· dition,however, thatthecopierpaythestatedperarticlecopyfeethrough the Copyright Clearance Center,Inc.,Operations Center,P.O.Box765,Schenectady, N,Y.12301,forcopying beyondthatpermitted bySections 107or108oftheU.S, Copyright Law.Thisconsent doesnotextendtootherkindsofcopying suchas copying forgeneral distribution. foradvertising orpromotional purposes. for creating newcollective works,orforresale. Paperspublished priorto1978mayalsobecopiedataperpaperleeof$2,50 undertheabovestatedconditions. SAEroutinely stocksprintedpapersforaperiodofthreeyearsfollowing dateof publication. DirectyourorderstoSAEOrdp.rDepartment. Toobtainquantity reprintrates.permission toreprintatechnical paperorper· mission tousecopyrighted SAEpublications inotherworks,contact theSAE Publications Division. AUSAtvaDe'.arc absrtacled and'rn'1e.ed,n IheSA"GIO!lal MO~!'IYDarabale SAEGLOBAL MOBILITY DATABASE Nopartofthispublication maybereproduced inanyform,in anelectronic retrieval systemorotherwise, without theprior writtenpermission ofthepublisher. ISSNOl48·7191 Copyright ©1988Society01Automotive Engineers, Inc. Positions andopinions advanced Inthispaperarethoseof theauthor{s) andnotnecessarily thoseofSAE.TheButhor Issolelyresponsible forthecontentofthepaper,Aprocess Isavailable bywhichdiscussions willbeprintedwiththe paperIfItIspublished InSAETransactions, Forpermission topublishthispaperInfullorInpart,contacttheSAE Publications DiVision.Personswishingtosubmitpaperstobeconsidered for presentation orpUblication throughSAEshouldsendthe manuscript ora300wordabstractofaproposed manus­ criptto:Secretary, Engineering ActivityBoard.SAE. PrintedInU.S.A.Downloaded from SAE International by ETH Bibliothek Zurich, Wednesday, March 08, 2017880481 The"ECVT"ElectroContinuously VariableTransmission Yasuhito Sakai FujiHeavyIndustries ltd. ABSTRACT Withthepopularization ofeasydriving inJapan,thequesttoimprove thefueleconomy andvehicle performance ofasmallcarwitha torqueconverter automatic transmission (AT) hasledtothedevelopment oftheElectro Con­ tinuously Variable Transmission (ECVT). The Subaru ECVTwhichcombines anelectronically controlled magnetic powderclutchwiththevan Doorne's steelbeltdrivesystem employs a coupleofconventional synchromeshes asameans offorward/reverse change-over mechanism and simplehydraulic control valves. Thiscombina­ tionhasrealized smoothness andquickresponse ofCVToperation andprovides acompact size fortheCVTwiththeweightof45.4kg.Fuel economy ofSubaruJustyECVTcarwiththeone literengineisthusimproved by15to20%in Japanese 10-mode testcycleandatthe60km/H constant speedrespectively incomparison with thatofthreespeedstorqueconverter AT.The description ofthetransmission anditscontrol strategy inclUding thepowderclutchare presented. AUTOMATIC TRANSMISSIONS (AT)equipped with torqueconverters areapproaching thestageof maturity intermsofbothfunction andreliabi­ lity,evenwiththetrendforagreater number ofgearpositions toselect, advances madein lockupmechanism, electronic control, etc.For light,miniandso-called one-liter enginecars, however, weakness/limitations ofautomatic transmissions equipped withtorqueconverters areinevitably noticed inrelation topowerand fueleconomy. Itisthusdifficult todenythat saiddifferences frommanualtransmission vehicles arebecoming morepronounced thanever. Asameanstoovercome suchdemerits ofAT, Subaru ECVT(Electro Continuously Variable Transmission) hasbeendeveloped