汽车变速器的设计外文文献翻译、中英文翻译、外文翻译.docx
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汽车变速器的设计外文文献翻译、中英文翻译、外文翻译.docx
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外文原文
AutomobileTransmissionDesign
Abstract
Thetopicofthisprojectisadesignoftransmissionsforamedium-sizetruck.Theadoptionofsuitabledesignsandlayoutenablestheeffectiveutilizationofenginetoimprovethetruck'smotilityandeconomy.ThedesignwasreferredtoparametersofBeijingFotontruckandrelevantbooks.Viaacomprehensivedemonstration,thedatawascollectedfromvariouscomponentsofthetransmissionwhichweremodeledbySolidworks.Thetransmissionisafive-speedtransmission,includingfiveforwardgearsandonereversegear,applyingadvancedmonolithicstructureoftheintermediateshaftandtheshiftlockring-typesynchronizer.Thegearboxpossessesacompactstructure,asmallsize,hightransmissionefficiency,andalargerratiorange,withgoodeconomyanddynamicperformance.
Keywords:
five-speed,intermediateshaft,synchronizer.
1.Introduction
Theroleoftransmission:
Transmissionchangesthespeedoftheengineandexportsdifferentrotationalspeed.Atlowrotationalspeed,hightorquecanbeobtained.Highspeedhasbetterefficiencybutthetorqueislow.So,whenyoustartamachineyouneedtostartatlowspeedandafterrunningthenchangehighrotationalspeedmaintainingahighefficiency.
Specifically,inordertoensuregoodtransmissionperformance,itshouldmeetthefollowingrequirements.
1)Choosethecorrectgearshiftnumberandtransmissiongearratios,andmaketheoptimalmatchingofengineparameterstoensurethatthecarhasgoodpowerandeconomy.
2)Setneutraltoensurethecarengineandthetransmissioncanseparateforalongtime.
3)Setreverse,sothatthecarcantravelbackwards.
4)Setthepoweroutputapparatus.
5)Shiftquickly,labor-saving,easily.
6)Reliable.Duringdriving,thetransmissioncannotout-of-mesh,randommesh.
7)Transmissionshouldhaveahighefficiency.
8)Transmissionshouldbesimple,smooth,nonoise.
2.Demonstrationprogram
2.1Selecttransmissiontype
Therearemanytypesoftransmissions.
Bythenumberofforwardgears,transmissionscanbedividedintothree,four,five-speedandthemulti-speedtransmission,fivespeedtransmissionwaschosen.Accordingtotheshaftofdifferentform,transmissioncanbedividedintofixedshaftandrotatingshaft(oftenwithplanetarygeartransmission)twokindsoftransmissions.Themaincharacteristicoffixedaxistransmissioniseasytorealizeautomaticshiftwidelyused.Twoshafttransmissionforfrontenginefront-wheeldrive.Theshaftofrotationtypeismainlyusedforhydraulicmechanicaltransmission.Fixedshafttypewaschosen.
Accordingtothenumberofdifferentshafts,thetransmissioncanbedividedintotwo-shafttransmission,layshafttransmissionandmultipleshaftstransmission.
2.1.1Two-shafttransmission
Ifthetransmissionratioissmall,weoftenchoosetwoshafttypes.Ithasthefollowingcharacteristics.
1.Thegearboxoutputshaftandthemaindrivinggearspeedreducermakeitanorganicwhole.
2.Whentheengineislongitudinallymounted,themainreducercanusespiralbevelgearorhypoidgear,whentheengineisheldhorizontally,itistappedwithacylindricalgear,therebysimplifyingthemanufacturingprocess.
3.Theothergearsadoptconstantmeshgeartransmission,exceptthereversegeardrive.
4.Mostofthesynchronizerofgearsattheendoftheoutputshaft.
5.Iflowgeartransmissionisrelativelylarge,thesizeofthestructureincreases,itnolongerhastheaboveadvantages,itcanonlydriverelativelysmallconditionsbeforeusingthisprogram.
6.Two-shafttransmissiondoesnothavedirectlygears,therefore,workingathighspeed,gearsandbearingsarebearing,gearnoise,andeasytobedamaged.
2.1.2Layshafttransmission
Fromastructuralview,therearethreeshafts:
thefirstandthesecondshaftareinthesameline,andtheyaredirectlyshifted.Whenusingdirectshifttransmission,gears,bearingsandthesecondshaftarenotloadingbearing.Theenginetorquethroughthefirstandsecondshafthavedirectoutput,andthetransmissionhashightransmissionefficiency-upto90%.Thismeansthatithaslesswearandlongservicelife,thus,noiseisalsosmaller.Becausetheefficiencyofdirectgearishigherthantheotherforwardgears,itincreasesthelifeofthetransmission.Whenthetransmissionpoweristransmittedthroughthefirstshaft(theintermediategearshaftandthesecondshaft),sothedistancebetweenthemisnottoolong,butthereisstillalargetransmissiongearratio.Highgearusesconstantmeshtransmission,whereaslowspeedgearcannotuseconstantmeshgear.Mosttransmissionschemesexceptfirstspeedgearshiftmechanismareusedinsynchronizationorclutchshift.Fewfirstspeedgearsarealsousedtosynchronizertypeorclutchtypeshift.Intermediateshafttransmissioniswidelyusedinvarioustypesofrear-drivecars.Thatisthereasonwhythestructureisadoptedtothedesign.Twinintermediateshafttransmissionsormultipleintermediateshafttypesarethemostlyusedinheavyvehicles.Asitdoesnotmatchwiththedesign,itisnotexaminedfurther.(Yu,2009,p.122)
2.2Gearselection
Therearetwotransmissiongears:
spurgearsandhelicalgears.Spurgearisusedforsliding.Itisappliedinreversegearandthefirstgearspecifically.Thestructureissimpleandeasytomanufacture,butwhenitisshifting,therootofthegeartoothispronetobringaboutnoise.Thatintensifiesthewearofgearsandlowersthelifeexpectancy.Andduetothenoise,iteasilyleadsintodriverfatigue.Helicalgearsoffersmoothtransmission,lowernoise,lowerwearandlongerlife.Thedrawbacksaretheaxialforcegeneratedwhenworkingandthestructureiscomplex.Thisdrawbackcanbebalancedwhenmakingthecalculationoftheshaft.
Bycomparingtheadvantagesanddisadvantagesofthetwoformsofthegears,reverseandthefirstspeedgearusestraightgear,whichisconsideringfollowingfactors:
thereversegearandthefirstspeedgeararelowusage.Measuringtheeconomyandpracticalityofthegearstructure,therestofthegearsarehelicalgears,thatdependsonhelicalgearhassmoothtransmissionandlowernoise.(Yu,2009,p.126)
2.3Shiftgearstructureselection
Transmissionshiftintroducesthreekindsofforms:
straightteethsliding,gearmeshingandsynchronizershifting.
2.3.1:
Straightteethslidinggear
Thisformiseasytomanufacture,hasasimplestructure,butincludesvariousdisadvantages.Itispronetoimpactsduetotheshift,leadingtofastwearing,lowerservicelifeandhighernoise.Therefore,itreducesthedrivingsafetyandcomfortofacar.Andtechnicalrequirementsofthedriveraretoohigh,whichcaninfluencethedrivingofthecar.
2.3.2:
Gearmeshing
Usingameshingshiftincreasesthenumberofgearteethtoreceivetheimpactloadduringthegearshift.Ingearmeshing,thegeartoothisnotinvolvedintheshift,soitisallowinglongerlifecycle.However,itcannoteliminateshiftimpact.
Therefore,thecarsafetyandridecomfortareaffectedbyacertainamount,andthetechnicalrequirementsofthedriveraretoohigh.Inaddition,duetoaddingthemeshandmeshgear,oftenmakesabigmomentofinertiaofrotatingpartsofthetransmission,sothiswayofshiftinggenerallyisappliedtosomeplacewithouthighdemandandheavylorry.
2.3.3Synchronizer
Thisshiftformcaneliminateshiftshockandtherapidshift.Andthemanipulationislight.Also,thedriver'srequestisnothigh.Eliminatingnoiseandshiftshockimprovesthecarridesafety,acceleration,comfortandeconomy.So,moderncarsaregenerallyusedinthisformbutduetoitscomplexstructure,manufacturingneedshighaccuracyrequirement.Themanufacturingofsynchronizerisdifficultandsynchronousringiseasytodamagebutitisstillwidelyused.Thisdesignadoptsthisshiftingform.(Yu,2009,p.130)
2.4Theformofreverseselection
Inordertoachievethereversedriveeasily.Carsareequippedwithareverseidlegearbetweenthelayshaftandoutputshaft.Thisprogramstructureissimpleandeasytoproduce.
Figure2.1Reversegears(DrawingbytheSolidworks).
2.5Transmissionstructure
Figure2.2Transmissionstructure(Drawingbyhand)
2.6Synchronizerselection
Synchronizertypicallyhasnormalpressuretype,inertiatypeandself-servotype.Amongthem,theinertiatypesynchronizerismorecommonlyused.
2.6.1Normalpressuresynchronizer
Thestructureofthesynchronizationstructureissimple.Becausetheengagementsleeveaxialresistanceiscausedbythespringpressure,thepressureoflimitedsizeisnotguaranteed.Sothisformofsynchronizerhasbeenappliedonlyonheavyvehicles.
Thetransmissiondoesnotusethissynchronizer.
2.6.2Self-servosynchronizer
ThesynchronizerisalsoknownasBosheErsynchronizer.Itcanensurethatonlyinthesynchronousstateshift,aslongasthereistheangularvelocitydifferencebetweenclutchandgears,thespringofsynchronizersupportsforcetostopsynchronizerringshrinking,soitpreventsmovementofmeshingsets.
Onlywhentheangularspeeddifferenceiszero,thespringunloadstheload,duetolosingtheresistanceofsynchronousring,shiftingprocesscanbeachieved.BosheErsynchronizerhashighfrictiontorque,simplestructure,reliableoperationandshortaxialdimension.Theymaketransmissionintrucksveryconvenient.
2.6.3Inertiatypesynchronizer
Thisformofsynchronizeristhesameasthenormalpressuretypesynchronizer.Itdependsonfrictioneffectofsynchronization.Butitcanensurethejointsetsandjointsplinegearringkeepdistancebeforethesynchronization,andavoidtheshockandnoisebetweentheteeth.Fromthestructuralterm,inertiatypesync
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