外文翻译汽车悬架工作原理Word格式文档下载.docx
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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