资源描述：
《汽车系统构造英文版lesson11manualtransmission.ppt》由会员上传分享，免费在线阅读，更多相关内容在工程资料-天天文库。
1、Lesson11ManualTransmissionCarsneedtransmissionsbecauseofthephysicsofthegasolineengine.First,anyenginehasaredline--amaximumrpmvalueabovewhichtheenginecannotgowithoutexploding.Second,engineshavenarrowrpmrangeswherehorsepowerandtorqueareattheirmaximum.Forexample,anenginemightproduceitsmaximumhorsepo
2、werat5,500rpm.Thetransmissionallowsthegearratiobetweentheengineandthedrivewheelstochangeasthecarspeedsupandslowsdown.Youshiftgearssotheenginecanstaybelowtheredlineandneartherpmbandofitsbestperformance.Ideally,thetransmissionwouldbesoflexibleinitsratiosthattheenginecouldalwaysrunatitssingle,best-p
3、erformancerpmvalue[1].Thatistheideabehindthecontinuouslyvariabletransmission(CVT).AtypicallayoutoftransmissionsystemACVThasanearlyinfiniterangeofgearratios.Inthepast,CVTscouldnotcompetewithfour-speedandfive-speedtransmissionsintermsofcost,sizeandreliability,soyoudidn'tseetheminproductionautomobil
4、es.Thesedays,improvementsindesignhavemadeCVTsmorecommon.TheToyotaPriusisahybridcarthatusesaCVT.Thetransmissionisconnectedtotheenginethroughtheclutch.Theinputshaftofthetransmissionthereforeturnsatthesamerpmastheengine.Mercedes-BenzC-classsportcoupe,six-speedmanualtransmission,graphicillustration.A
5、five-speedtransmissionappliesoneoffivedifferentgearratiostotheinputshafttoproduceadifferentrpmvalueattheoutputshaft.Herearesometypicalgearratios:GearRatioRPMatTransmissionOutputShaftwithEngineat3,000rpm1st2.315:11,2952nd1.568:11,9133rd1.195:12,5104th1.000:13,0005th0.915:13,278SimpleTransmissionTo
6、understandthebasicideabehindastandardtransmission,thediagrambelowshowsaverysimpletwo-speedtransmissioninneutral:neutralpositionofatwo-speedtransmissionLet'slookateachofthepartsinthisdiagramtounderstandhowtheyfittogether:Thegreenshaftcomesfromtheenginethroughtheclutch.Thegreenshaftandgreengeararec
7、onnectedasasingleunit.Theredshaftandgearsarecalledthelayshaft.Thesearealsoconnectedasasinglepiece,soallofthegearsonthelayshaftandthelayshaftitselfspinasoneunit.Thegreenshaftandtheredshaftaredirectlyconnectedthroughthei
