外文翻译汽车悬架工作原理.docx
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外文翻译汽车悬架工作原理
外文翻译--汽车悬架工作原理
附录3
英文原文
HowCarSuspensionsWork
ByWilliamHarris
UniversityofMichigan
Whenpeoplethinkofautomobileperformance,theynormallythinkofhorsepower,torqueandzero-to-60acceleration.Butallofthepowergeneratedbyapistonengineisuselessifthedrivercan'tcontrolthecar.That'swhyautomobileengineersturnedtheirattentiontothesuspensionsystemalmostassoonastheyhadmasteredthefour-strokeinternalcombustionengine.
PhotocourtesyHondaMotorCo.,Ltd.
Double-wishbonesuspensiononHondaAccord2005Coupe
Thejobofacarsuspensionistomaximizethefrictionbetweenthetiresandtheroadsurface,toprovidesteeringstabilitywithgoodhandlingandtoensurethecomfortofthepassengers.Inthisarticle,we'llexplorehowcarsuspensionswork,howthey'veevolvedovertheyearsandwherethedesignofsuspensionsisheadedinthefuture.
VehicleDynamics
Ifaroadwereperfectlyflat,withnoirregularities,suspensionswouldn'tbenecessary.Butroadsarefarfromflat.Evenfreshlypavedhighwayshavesubtleimperfectionsthatcaninteractwiththewheelsofacar.It'stheseimperfectionsthatapplyforcestothewheels.AccordingtoNewton'slawsofmotion,allforceshavebothmagnitudeanddirection.Abumpintheroadcausesthewheeltomoveupanddownperpendiculartotheroadsurface.Themagnitude,ofcourse,dependsonwhetherthewheelisstrikingagiantbumporatinyspeck.Eitherway,thecarwheelexperiencesaverticalaccelerationasitpassesoveranimperfection.
Withoutaninterveningstructure,allofwheel'sverticalenergyistransferredtotheframe,whichmovesinthesamedirection.Insuchasituation,thewheelscanlosecontactwiththeroadcompletely.Then,underthedownwardforceofgravity,thewheelscanslambackintotheroadsurface.Whatyouneedisasystemthatwillabsorbtheenergyoftheverticallyacceleratedwheel,allowingtheframeandbodytorideundisturbedwhilethewheelsfollowbumpsintheroad.
Thestudyoftheforcesatworkonamovingcariscalledvehicledynamics,andyouneedtounderstandsomeoftheseconceptsinordertoappreciatewhyasuspensionisnecessaryinthefirstplace.Mostautomobileengineersconsiderthedynamicsofamovingcarfromtwoperspectives:
Ride-acar'sabilitytosmoothoutabumpyroad
Handling-acar'sabilitytosafelyaccelerate,brakeandcorner
Thesetwocharacteristicscanbefurtherdescribedinthreeimportantprinciples-roadisolation,roadholdingandcornering.Thetablebelowdescribestheseprinciplesandhowengineersattempttosolvethechallengesuniquetoeach.
Acar'ssuspension,withitsvariouscomponents,providesallofthesolutionsdescribed.
Let'slookatthepartsofatypicalsuspension.
TheChassis
Thesuspensionofacarisactuallypartofthechassis,whichcomprisesalloftheimportantsystemslocatedbeneaththecar'sbody.
Thesesystemsinclude:
Theframe-structural,load-carryingcomponentthatsupportsthecar'sengineandbody,whichareinturnsupportedbythesuspension
Thesuspensionsystem-setupthatsupportsweight,absorbsanddampensshockandhelpsmaintaintirecontact
Thesteeringsystem-mechanismthatenablesthedrivertoguideanddirectthevehicle
Thetiresandwheels-componentsthatmakevehiclemotionpossiblebywayofgripand/orfrictionwiththeroad
Sothesuspensionisjustoneofthemajorsystemsinanyvehicle.
Withthisbig-pictureoverviewinmind,it'stimetolookatthethreefundamentalcomponentsofanysuspension:
springs,dampersandanti-swaybars.Springs
Today'sspringingsystemsarebasedononeoffourbasicdesigns:
CoilspringsThisisthemostcommontypeofspringandis,inessence,aheavy-dutytorsionbarcoiledaroundanaxis.Coilspringscompressandexpandtoabsorbthemotionofthewheels.
Leafsprings-Thistypeofspringconsistsofseverallayersofmetal(called"leaves")boundtogethertoactasasingleunit.Leafspringswerefirstusedonhorse-drawncarriagesandwerefoundonmostAmericanautomobilesuntil1985.Theyarestillusedtodayonmosttrucksandheavy-dutyvehicles.
Torsionbars-Torsionbarsusethetwistingpropertiesofasteelbartoprovidecoil-spring-likeperformance.Thisishowtheywork:
Oneendofabarisanchoredtothevehicleframe.Theotherendisattachedtoawishbone,whichactslikealeverthatmovesperpendiculartothetorsionbar.Whenthewheelhitsabump,verticalmotionistransferredtothewishboneandthen,throughtheleveringaction,tothetorsionbar.Thetorsionbarthentwistsalongitsaxistoprovidethespringforce.Europeancarmakersusedthissystemextensively,asdidPackardandChryslerintheUnitedStates,throughthe1950sand1960s.
Airsprings-Airsprings,whichconsistofacylindricalchamberofairpositione