外文翻译汽车悬架工作原理.docx

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