车辆工程专业毕业设计外文翻译5

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1、外文资料TransmissionsTransmissionshavetocompromiseoneitherridecomfortorefficiency,butanewapproachtothedogengagementgearboxcouldimproveboth.Withtighteningemissionsregulations,carmakersarenotjustconfiningtheireffortstoimprovingcombustionandafter-treatment.Manyarefindingthatmodernenginesaresoad

2、vancedthatthebenefitsofsomeenginetechnologiesaresmallcomparedtothehugedevelopmentcostsinvolved.It'simportanttolookatthewholevehicleinordertoimproveemissions.Asthesecondmostexpensivepieceofkitinthecar,thetransmissionisthelogicalnextplacetolook.Ofalltransmissiontechnologies,themanualgearbo

3、xisthemostefficient;around96percentoftheenergythatisputincomesoutoftheotherend.Butnoteveryonecandriveoneorwantsto.Becauseyouhavetodiptheclutchpedal,it'slesscomfortabletodriveinheavytraffic.Itmakesthedrivertiredandthetorqueinterruptions'head-nodeffectonpassengerscanbewearing.Thedriver'scl

4、utchcontrolandcorrespondingtorqueinterruptionsarealsothemanual'sweakpoint.Whenacceleratingupthroughthegearbox,eachup-shiftrequiresthedrivertocutthetorquemomentarilybyliftingthegaspedalanddippingtheclutch.Itmayjusttakeasecondtocompletetheoperation,butduringthistimethevehicleislosingspeeda

5、ndacceleration.Attheoppositeandofthespectrumisthetraditionalautomatic.Itsshiftqualityisgoodthankstoitstorqueconverter,butefficiencyisrelativelypoordespiterecentadvances.Becauseofthis,alotofthecurrentresearchistryingtofindanefficientalternativetotheconventionalautomatic.Themaintechnologie

6、sarecontinuouslyvariabletransmissions(CVTs);dualclutchtransmissions(DCTs)andautomatedmanualtransmissions(AMTs).Theyallofferdifferentbenefitsovertheconventionalplanetaryautomatic.TheCVTusesabeltchainortoroidalshapeddishdrivetovaryaninfinitenumberofgearratios.Ithasimprovedefficiencyandcost

7、whencomparedtoconventionalautomatics.Itsadvantagecomesfromitssimplicitu.Itconsistsofveryfewcomponents;usuallyarubberormetal-linkbelt;ahydraulicallyoperateddrivingpulley,amechanicaltorque-sensingdrivingpulley,microprocessorsandsomesensors.Thetransmissionsworksbyvaryingthed