机械设计方案自动化英语翻译.docx

机械设计方案自动化英语翻译.docx

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机械设计方案自动化英语翻译

原文：

CHASSIS

1.clutch

Theengineproducesthepowertodrivethevehicle.Thedrivelineordrivetraintransferthepoweroftheenginetothewheels.Thedrivetrainconsistsofthepartsfromthebackoftheflywheeltothewheels.Thesepartsincludetheclutch,thetransmission,thedriveshaft,andthefinaldriveassembly.

Theclutchwhichincludestheflywheel,clutchdisc,pressureplate,springs,pressureplatecoverandthelinkagenecessarytooperatetheclutchisarotatingmechanismbetweentheengineandthetransmission.Itoperatesthroughfrictionwhichcomesfromcontactbetweentheparts.Thatisthereasonwhytheclutchiscalledafrictionmechanism.Afterengagement,theclutchmustcontinuetotransmitallenginetorquetotransmissiondependingonthefrictionwithoutslippage.Theclutchisalsousedtodisengagetheenginefromthedrivetrainwheneverthegearsinthetransmissionarebeingshiftedfromgearratiotoanother.

Tostarttheengineorshiftthegears,thedriverhastodepresstheclutchpedalwiththepurposeofdisengagementthetransmissionfromtheengine.Atthattime,thedrivenmembersconnectedtothetransmissioninputshaftareeitherstationaryorrotatingataspeedthatissloweroffasterthanthedrivingmembersconnectedtoenginecrankshaft.Thereisnospringpressureontheclutchassemblyparts.Sothereisnofrictionbetweenthedrivingmembersanddrivenmembers.Asthedriverletsloosetheclutchpedal,springpressureincreaseontheclutchparts.Frictionbetweenthepartsalsoincreases.Thepressureexertedbythespringsonthedrivenmembersiscontrolledbythedriverthroughtheclutchpedalandlinkage.Thepositiveengagementofthedrivinganddrivenmembersismadepossiblethefrictionbetweenthesurfacesofthemembers.Whenfullspringpressureisapplied,thespeedofthedrivinganddrivenmembersshouldbethesame.Atthemoment,theclutchmustactasacouplingdeviceandtransmitallenginepowertothetransmission,withoutslipping.

However,thetransmissionshouldbeengagedtotheenginegraduallyinordertooperatethecarsmoothlyandminimizetorsionalshockonthedrivetrainbecauseanengineatidlejustdeveloplittlepower.Otherwise,thedrivingmembersareconnectedwiththedrivenmemberstooquicklyandtheenginewouldbestalled.

Theflywheelisamajorpartoftheclutch.Theflywheelmountstotheenginecrankshaftandtransmitsenginetorquetotheclutchassembly.Theflywheel,whencoupledwiththeclutchdiscandpressureplatemakesandbreakstheflowofpowertheenginetothetransmission.

Theflywheelprovidesamountinglocationfortheclutchassemblyaswell.Whentheclutchisapplied,theflywheeltransfersenginetorquetotheclutchdisc.Becauseofitsweight,theflywheelhelpstosmoothengineoperation.Theflywheelalsohasalargeringgearatitsouteredge,whichengageswithapiniongearonthestartermotorduringenginecranking.

Theclutchdiscfitsbetweentheflywheelandthepressureplate.Theclutchdischasasplinedhubthatfitsoversplinesonthetransmissioninputshaft.Asplinedhubhasgroovesthatmatchsplinesontheshaft.Thesesplinesfitinthegrooves.Thus,thetwopartsheldtogether.However,back¨Cand¨Cforthmovementofthediscontheshaftispossible.Attachedtotheinputshaft,thediscturnsatthespeedoftheshaft.

Theclutchpressureplateisgenerallymadeofcastiron.Itisroundandaboutthesamediameterastheclutchdisc.Onesideofthepressureplateismachinedsmooth.Thissidewillpresstheclutchdiscfacingareagainsttheflywheel.Theoutersidehasshapestofacilitateattachmentofspringandreleasemechanism.Thetwoprimarytypesofpressureplateassembliesarecoilspringassemblyanddiaphragmspring.

Inacoilspringclutchthepressureplateisbackedbyanumberofcoilspringsandhousedwiththeminapressed¨Csteedcoverboltedtotheflywheel.Thespringpushagainstthecover.Neitherthedrivenplatenorthepressureplateisconnectedrigidlytotheflywheelandbothcanmoveeithertowardsitoaway.Whentheclutchpedalisdepressedathrustpadridingonacarbonorballthrustbearingisforcedtowardstheflywheel.Leverspivotedsothattheyengagewiththethrustpadatoneendandthepressureplatetattheotherendpullthepressureplatebackagainstitssprings.Thisreleasespressureonthedrivenplatedisconnectingthegearboxfromtheengine.

Diaphragmspringpressureplateassembliesarewidelyusedinmostmoderncars.Thediaphragmspringisasinglethinsheetofmetalwhichyieldswhenpressureisappliedtoit.Whenpressureisremovedthemetalspringbacktoitsoriginalshape.Thecenterportionofthediaphragmspringisslitintonumerousfingersthatactasreleaselevers.Whentheclutchassemblyrotateswiththeenginetheseweightsareflungoutwardsbycentrifugalplateandcausetheleverstopressagainstthepressureplate.Duringdisengagementoftheclutchthefingersaremovedforwardbythereleasebearing.Thespringpivotsoverthefulcrumringanditsouterrimmovesawayfromtheflywheel.Theretractingspringpullsthepressureplateawayfromtheclutchplatethusdisengagingtheclutch.

Whenengagedthereleasebearingandthefingersofthediaphragmspringmovetowardsthetransmission.Asthediaphragmpivotsoverthepivotringitsouterrimforcesthepressureplateagainsttheclutchdiscsothattheclutchplateisengagedtoflywheel.

Theadvantagesofadiaphragmtypepressureplateassemblyareitscompactness,lowerweight,fewermovingparts,lessefforttoengage,reducesrotationalimbalancebyprovidingabalancedforcearoundthepressureplateandlesschancesofclutchslippage.

Theclutchpedalisconnectedtothedisengagementmechanismeitherbyacableor,morecommonly,byahydraulicsystem.Eitherway,pushingthepedaldownoperatesthedisengagementmechanismwhichputspressureonthefingersoftheclutchdiaphragmviaareleasebearingandcausesthediaphragmtoreleasetheclutchplate.Withahydraulicmechanism,theclutchpedalarmoperatesapistonintheclutchmastercylinder.Thisforceshydraulicfluidthroughapipetothecutchreleasecylinderwhereanotheroperatestheclutchdisengagementmechanismbyacable.

Theotherpartsincludingtheclutchfork,releasebearing,bell¨Chousing,bellhousingcover,andpilotbushingareneededtocoupleanduncouplethetransmission.Theclutchfork,whichconnectstothelinkage,actuallyoperatestheclutch.Thereleasebearingfitsbetweentheclutchforkandthepressureplateassembly.Thebellhousingcoverstheclutchassembly.Thebellhousingcoverfastenstothebottomofthebellhousing.Thisremovablecoverallowsamechanictoinspecttheclutchwithoutremovingthetransmissionandbellhousing.Apilotbushingfitsintothebackofthecrankshaftandholdsthetransmissioninputshaft.

2automatictransmission

Themodernautomatictransmissionisbyfar,themostcomplicatedmechanicalcomponentintoday¡¯sautomobile.Itisatypeoftransmissionthatsiftsitself.Afluidcouplingortorqueconverterisusedinsteadofamanuallyoperatedclutchtoconnectthetransmissiontotheengine.

Therearetwobasictypesofautomatictransmissionbasedonwhetherthevehicleisrearwheeldriveorfrontwheeldrive.Onarearwheeldrivecar,thetransmissionisusuallymountedtothebackoftheengineandislocatedunderthehumpinthecenterofthefloorboardalongsidethegaspedalposition.Adriveshaftconnectsthetransmissiontothefinaldrivewhichislocatedintherearaxleandisusedtosendpowertotherearwheels.Powerflowonthissystemissimpleandstraightforwardgoingfromtheengine,throughthetorqueconverter,thentroughthetransmissionanddriveshaftuntilitreachesthefinaldrivewhereitissplitandsenttothetworeartransmission.

Onafrontwheeldrivecar,thetransmissionisusuallycombinedwiththefinaldrivetoformwhatiscalledatransaxle.Theengineonafrontwheeldrivecarisusuallymountedsidewaysinthecarwiththetransaxletuckedunderitonthesideoftheenginefacingtherearofthecar.Frontaxlesareconnecteddirectlytothetransaxleandprovidepowertofrontwheels.Inthisexample,powerfloesfromtheengine,throughthetorqueconvertertoalargerchainthatsendsthepowerthrougha180degreeturntothetransmissionthatisalongsidetheengine.Fromthere,thepowerisroutedthroughthetransmissiontothefinaldrivewhereitissplitandsenttothetwofrontwheelsthroughthedriveaxles.

Thereareanumberofotherarrangementsincludingfrontdrivevehicleswheretheengineismountedfronttobackinsteadofsidewaysandthereareothersystemsthatdriveallfourwheelsbutthetwosystemsdescribedherearebyfarthemostpopular.Amuchlesspopularrearandisconnectedbyadriveshafttothetorqueconverterwhichisstillmountedontheengine.ThissystemisfoundonthenewCorvetteandisusedinordertobalancetheweightevenlybetweenthefrontandrearwheelsforimprovedperformanceandhandling.Anotherreardrivesystemmountseverything,theengine,transmissionandfinaldriveintherear.ThisrearenginearrangementispopularonthePorsche.

Themodernautomatictransmissionconsistsofmanycomponentsandsystemsthatdesignedtoworktogetherinasymphonyofplanetarygearsets,thehydraulicsystem,sealsandgaskets,thetorqueconverter,thegovernorandthemodulatororthrottlecableandcomputercontrolsthathasevolvedovertheyearsintow