1 汽车专业英语课件-汽车基础知识部分-section 1汽车专业英语2版ppt课件--20180227Chapter 3 1-3 4

复习,翻译句子英文专业词汇发动机分类，发动机零件/系统;汽车分类，汽车组成_,学习内容,本次课学习内容、目标和重点难点,学习目标,难点重点,Clutch，ManuelTransmissionPropellerShaftsandUniversalJoints3.FinalDrive,DifferentialandAxleShaft,1.掌握手动变速汽车传动系统主要组成、各部件主要零件的英文名称2.提高翻译技巧，能较熟练翻译课文,1.重点是英文专业术语记忆2.难点是生词偏多,Chapter3PowerTrain3.1Clutches,3.1.1NewWordsandPhrases,Chapter3PowerTrain3.1Clutches,Theclutchwhichincludestheflywheel,clutchdisc,pressureplate,springs,pressureplatecoverandthelinkagenecessarytooperatetheclutchisarotatingmechanismbetweentheengineandthetransmission.Itoperatesthroughfrictionwhichcomesfromcontactbetweentheparts.Thatisthereasonwhytheclutchiscalledafrictionmechanism.Afterengagement,theclutchmustcontinuetotransmitalltheenginetorquetothetransmissiondependingonthefrictionwithoutslippage.Theclutchisalsousedtodisengagetheenginefromthedrivetrainwheneverthegearsinthetransmissionarebeingshiftedfromonegearratiotoanother.,Chapter3PowerTrain3.1Clutches,3.1.2Text,Tostarttheengineorshiftthegears,thedriverhastodepresstheclutchpedalwiththepurposeofdisengagementthetransmissionfromtheengine.Atthattime,thedrivenmembersconnectedtothetransmissioninputshaftareeitherstationaryorrotatingataspeedthatisslowerorfasterthanthedrivingmembersconnectedtotheenginecrankshaft.Thereisnospringpressureontheclutchassemblyparts.Sothereisnofrictionbetweenthedrivingmembersanddrivenmembers.Asthedriverletsloosetheclutchpedal,springpressureincreasesontheclutchparts.Frictionbetweenthepartsalsoincreases.,Chapter3PowerTrain3.1Clutches,Thepressureexertedbythespringsonthedrivenmembersiscontrolledbythedriverthroughtheclutchpedalandlinkage.Thepositiveengagementofthedrivinganddrivenmembersismadepossiblebythefrictionbetweenthesurfacesofthemembers.Whenfullspringpressureisapplied,thespeedofthedrivinganddrivenmembersshouldbethesame.Atthemoment,theclutchmustactasasolidcouplingdeviceandtransmitallenginepowertothetransmission,withoutslipping.,Chapter3PowerTrain3.1Clutches,Fig.3-1Structureofaclutch,Chapter3PowerTrain3.2ManuelTransmission,3.1.1NewWordsandPhrases,Chapter3PowerTrain3.2ManuelTransmission,Chapter3PowerTrain3.2ManuelTransmission,Chapter3PowerTrain3.2ManuelTransmission,Chapter3PowerTrain3.2ManuelTransmission,Themodernmanualtransmissioncanprovidethedriverwithuptosixforwardgearratios.Thereductiongearsprovidegearratiosofapproximately3.5:1(statedas3.5to1)forthelowestgear,toabout1.5:1forthehighest.Thedirectdrivegearhasa1:1gearratio.Theoverdrivegearshaveagearratioofabout0.7:1.Byselectingoneoftheratios,itispossibletooperatethevehicleunderallnormalconditions.Inaddition,torqueismultipliedmorethroughthedifferentialgears.Ratiosvaryfromvehicletovehicle,dependingonenginehorsepowerandvehicleweight.Areversegearisalsoused.Thereverseratioisusuallyabout3:1.Thefive-speedtransmissionhasanoverdriveratio.Theoverdriveratioisincorporatedintonewertransmissionstoincreasefuelmileageandloweremissions.,Chapter3PowerTrain3.2ManuelTransmission,1.TransmissionGearRatios,3.2.1Text,Atypicaltransmissionconsistsofacase,fourshafts,bearings,gears,synchronizers,andashiftingmechanism.1）TransmissionCaseThetransmissioncaseholdsthetransmissiongears,shafts,bearings,andwashers.Itboltstotherearoftheengine,ortotheclutchhousing.Manytransmissioncasesandclutchhousingsareone-pieceunits.Mosttransmissioncasesaremadeofcastironoraluminumandhaveaseparateextensionhousing,whichsupportstheoutputshaft.Thishousingmayalsocontainthespeedometergear.Therearenginemountisusuallyattachedtotheextensionhousing.,Chapter3PowerTrain3.2ManuelTransmission,2.TransmissionConstruction,2）TransmissionGearTransmissiongearsaremadeofhighqualitysteel,carefullyheat-treatedtoproducesmooth,hardsurfacegearteethwithasofter,butverytoughinterior.Theyaredrop-forged(machinehammeredintoshape)whileredhot.Theteethandothercriticalareasarecutonprecisionmachinery.Theteethontransmissiongearsarecutintospurandhelicalpatterns.Thehelicalgearissuperiorinthatitrunsmorequietlyandisstrongerbecausemoretoothareaisincontact.Helicalgearsmustbemountedfirmly,sincethereisatendencyforthemtoslideapartduetothespiralshape.Gearendplayintheclustergearandsomeothergearsandshaftsiscontrolledbytheuseofbronzeandsteelthrustwashers.Thesewashersareinstalledontheendofthegearshaftsbetweenthemovinggearsandthestationarytransmissioncase.,Chapter3PowerTrain3.2ManuelTransmission,Theremustbesomeclearancebetweenthegearteethtoallowforlubrication,expansionandpossiblesizeirregularity.Thisclearanceisverysmall(afewthousandthsofaninch).3）SynchronizingMechanismOncethevehicleisinmotion,thedrivelinewillturntheoutputshaftcontinuously.Asaresult,theslidinggearswillalsobeturning.Whenanattemptismadetomeshthemwithanyoftheclustergears(whichtendtostopwhentheclutchisdepressed),thegearteethwillbesubjectedtodamagingimpactforces.Thesoundofgearclashwhenshiftingresultsfromtheslidinggearteethliterallysmashingagainsttheclustergear.,Chapter3PowerTrain3.2ManuelTransmission,Itisobviousthatforonegeartomeshwithanotherquietlyandwithoutdamage,bothgearsmustberotatingatnearlythesamespeed.Modernmanualtransmissionsandtransaxleshavesynchronizedgears,withspecialinternalclutchestopreventgearclashwhenshifting.Thepurposeofthesynchronizeristomoveaheadoftheunitthatistobemeshed,seizetheotherunit,andbringtherotationalspeedofbothunitstogether.Oncebothunitsarerotatingatthesamespeed,theymaybemeshed.,Chapter3PowerTrain3.2ManuelTransmission,Fig.3-2Manueltransmission,3.ManualTransaxleManualtransaxle(Fig.3-3toFig.3-6)isusedonfrontwheeldrivevehicle.Itcombinesthegearbox,finaldrive,differentialandaxlehousingintoasingleunit.,仔细研究下面几张图，弄清手动变速驱动桥的结构：变速驱动桥壳-变速器壳-后盖换档元件、传动组件/总成输入轴组件输出轴组件,Chapter3PowerTrain3.2ManuelTransmission,Fig.3-3Manualtransaxlecomponents,变速驱动桥壳,变速器壳,后盖,Fig.3-4Inputshaft,outputshaftandshiftmechnismcomponents,换档元件,传动组件/总成,Fig.3-5Inputshaftassembly,输入轴组件,Fig.3-6Outputshaftassembly,输出轴组件,Chapter3PowerTrain3.3PropellerShaftsandUniversalJoints,3.3.1NewWordsandPhrases,Therear-wheeldriveshaftishollowtoreduceweight,buthasadiameterlargeenoughtogivetheshaftgreatstrength.Steel,aluminum,andgraphiteareusedindriveshaftconstruction.Somehavearubber-mountedtorsionaldamper.Ayokeandsplinedstub(whereused)areweldedtotheendsofahollowshaft.Theshaftmustruntrueandbecarefullybalancedtoavoidvibrations.Thedriveshaftisoftenturningathighspeedsandcancausegreatdamageifbent,imbalanced,orifthereiswearintheflexiblejoints.,Chapter3PowerTrain3.3PropellerShaftsandUniversalJoints,3.3.2Text,1.DriveShaft,Fig.3-7Thedriveshafttransferspowertothedrivewheels,Fig.3-8Structureofadriveshaft,2.UniversalJointThecrossandrolleruniversaljoint,sometimescalledacardanuniversaljoint,consistsofacentercrossandtwoyokes.Theyokesareattachedtothecrossthroughneedlebearingassemblies,usuallycalledbearingcaps.Thebearingcapsareretainedintheyokebysnaprings,U-bolts,orboltedplates.Thebearingcaprollerssurroundthecrossends.Thesecrossendsarecalledtrunnions.Thisallowstheyokestoswivelonthecrosswithaminimumamountoffriction.,Chapter3PowerTrain3.3PropellerShaftsandUniversalJoints,Fig.3-9Acrossandrolleruniversaljoint,Chapter3PowerTrain3.4FinalDrive,DifferentialandAxleShaft,3.4.1NewWordsandPhrases,Mostcarshaveastandard,orunlimited-slip,differential.(Alimited-slipdifferentialcostsmoreandisnotnecessaryinmostnormaldrivingconditions.)Asmentioned,adifferentialmustsplitpowerunequallywhenacargoesaroundacorner.Likethetransmission,thedifferentialhasmanygearsandparts.Thefinaldriveassemblyprovidesgearreductionsothatthedr