汽车悬架英文

SuspensionPrincipleOfWorkWhenpeoplethinkofautomobileperformance,theynormallythinkofhorsepower,torqueandzero-to-60acceleration.Butallofthepowergeneratedbyapistonengineisuselessifthedrivercan'tcontrolthecar.That'swhyautomobileengineersturnedtheirattentiontothesuspensionsystemalmostassoonastheyhadmasteredthefour-strokeinternalcombustionengine.Thejobofacarsuspensionistomaximizethefrictionbetweenthetiresandtheroadsurface,toprovidesteeringstabilitywithgoodhandlingandtoensurethecomfortofthepassengers.Inthisarticle,we'llexplorehowcarsuspensionswork,howthey'veevolvedovertheyearsandwherethedesignofsuspensionsisheadedinthefuture.VehicleDynamicsIfaroadwereperfectlyflat,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'sabilitytosmoothoutabumpyroadHandling-acar'sabilitytosafelyaccelerate,brakeandcornerThesetwocharacteristicscanbefurtherdescribedinthreeimportantprinciples-roadisolation,roadholdingandcornering.Thetablebelowdescribestheseprinciplesandhowengineersattempttosolvethechallengesuniquetoeach.PrincipleDefinitionGoalSolutionRoadIsolationThevehicle'sabilitytoabsorborisolateroadshockfromthepassengercompartmentAllowthevehiclebodytorideundisturbedwhiletravelingoverroughroads.Absorbenergyfromroadbumpsanddissipateitwithoutcausingundueoscillationinthevehicle.RoadHoldingThedegreetowhichacarmaintainscontactwiththeroadsurfaceinvarioustypesofdirectionalchangesandinastraightlineKeepthetiresincontactwiththeground,becauseitisthefrictionbetweenthetiresandtheroadthataffectsavehicle'sMinimizethetransferofvehicleweightfromsidetosideandfronttoback,asthistransferofweightreducesthe(Example:Theweightofacarwillshiftfromthereartirestothefronttiresduringbraking.Becausethenoseofthecardipstowardtheroad,thistypeofmotionisknownasdive.Theoppositeeffect--squat--occursduringacceleration,whichshiftstheweightofthecarfromthefronttirestotheback.)abilitytosteer,brakeandaccelerate.tire'sgripontheroad.CorneringTheabilityofavehicletotravelacurvedpathMinimizebodyroll,whichoccursascentrifugalforcepushesoutwardonacar'scenterofgravitywhilecornering,raisingonesideofthevehicleandTransfertheweightofthecarduringcorneringfromthehighsideofthevehicletothelowside.loweringtheoppositeside.Acar'ssuspension,withitsvariouscomponents,providesallofthesolutionsdescribed.Let'slookatthepartsofatypicalsuspension,workingfromthebiggerpictureofthechassisdowntotheindividualcomponentsthatmakeupthesuspensionproper.TheChassisThesesystemsinclude:Theframe-structural,load-carryingcomponentthatsupportsthecar'sengineandbody,whichareinturnsupportedbythesuspensionThesuspensionsystem-setupthatsupportsweight,absorbsanddampensshockandhelpsmaintaintirecontactThesteeringsystem-mechanismthatenablesthedrivertoguideanddirectthevehicleThetiresandwheels-componentsthatmakevehiclemotionpossiblebywayofgripand/orfrictionwiththeroadSothesuspensionisjustoneofthemajorsystemsinanyvehicle.SpringsToday'sspringingsystemsarebasedononeoffourbasicdesigns:Coilsprings-Thisisthemostcommontypeofspringandis,inessence,aheavy-dutytorsionbarcoiledaroundanaxis.Coilspringscompressandexpandtoabsorbthemotionofthewheels.Leafsprings-Thistypeofspringconsistsofseverallayersofmetal(calledleaves)boundtogethertoactasasingleunit.Leafspringswerefirstusedonhorse-drawncarriagesandwerefoundonmostAmericanautomobilesuntil1985.Theyarestillusedtodayonmosttrucksandheavy-dutyvehicles.Torsionbars-Torsionbarsusethetwistingpropertiesofasteelbartoprovidecoil-spring-likeperformance.Thisishowtheywork:Oneendofabarisanchoredtothevehicleframe.Theotherendisattachedtoawishbone,whichactslikealeverthatmovesperpendiculartothetorsionbar.Whenthewheelhitsabump,verticalmotionistransferredtothewishboneandthen,throughtheleveringaction,tothetorsionbar.Thetorsionbarthentwistsalongitsaxistoprovidethespringforce.Europeancarmakersusedthissystemextensively,asdidPackardandChryslerintheUnitedStates,throughthe1950sand1960s.Airsprings-Airsprings,whichconsistofacylindricalchamberofairposition