汽车悬架工作原理全英文

HowCarSuspensionsWorkTableofContents:›IntroductiontoHowCarSuspensionsWork›VehicleDynamics›TheChassis›Springs›Springs:SprungandUnsprungMass›Dampers:ShockAbsorbers›Dampers:StrutsandAnti-swayBars›SuspensionTypes:Front›SuspensionTypes:Rear›SpecializedSuspensions:TheBajaBug›SpecializedSuspensions:FormulaOneRacers›SpecializedSuspensions:HotRods›TheFutureofCarSuspensions›LotsMoreInformation›ComparePricesforCarSuspensionsWhenpeoplethinkofautomobileperformance,theynormallythinkofHYPERLINK"http://auto.howstuffworks.com/horsepower.htm"horsepower,torqueandzero-to-60acceleration.ButallofthepowergeneratedbyaHYPERLINK"http://auto.howstuffworks.com/engine.htm"pistonengineisuselessifthedrivercan'tcontrolthecar.That'swhyautomobileengineersturnedtheirattentiontothesuspensionsystemalmostassoonastheyhadmasteredthefour-strokeinternalcombustionengine.PhotocourtesyHondaMotorCo.,Ltd.Double-wishbonesuspensiononHondaAccord2005CoupeThejobofacarsuspensionistomaximizethefrictionbetweenthetiresandtheroadsurface,toprovidesteeringstabilitywithgoodhandlingandtoensurethecomfortofthepassengers.Inthisarticle,we'llexplorehowcarsuspensionswork,howthey'veevolvedovertheyearsandwherethedesignofsuspensionsisheadedinthefuture.VehicleDynamics（汽车动力学）Ifaroadwereperfectlyflat,withnoirregularities,suspensionswouldn'tbenecessary.Butroadsarefarfromflat.Evenfreshlypavedhighwayshavesubtleimperfectionsthatcaninteractwiththewheelsofacar.It'stheseimperfectionsthatapplyforcestothewheels.AccordingtoNewton'slawsofmotion（牛顿运动理论）,allforceshavebothmagnitude（巨细）anddirection.Abump（撞击）intheroadcausesthewheeltomoveupanddownperpendicular（垂直的）totheroadsurface.Themagnitude,ofcourse,dependsonwhetherthewheelisstrikingagiantbumporatinyspeck（斑点）.Eitherway,thecarwheelexperiencesaverticalaccelerationasitpassesoveranimperfection.Withoutanintervening（介入）structure,allofwheel'sverticalenergyistransferredtotheframe,whichmovesinthesamedirection.Insuchasituation,thewheelscanlosecontactwiththeroadcompletely.Then,underthedownwardforceofgravity,thewheelscanslambackintotheroadsurface.Whatyouneedisasystemthatwillabsorbtheenergyoftheverticallyacceleratedwheel,allowingtheframeandbodytorideundisturbedwhilethewheelsfollowbumpsintheroad.Thestudyoftheforcesatworkonamovingcariscalledvehicledynamics,andyouneedtounderstandsomeoftheseconceptsinordertoappreciatewhyasuspensionisnecessaryinthefirstplace.Mostautomobileengineersconsiderthedynamicsofamovingcarfromtwoperspectives:Ride-acar'sabilitytosmoothoutabumpyroadHandling-acar'sabilitytosafelyaccelerate,brakeandcornerThesetwocharacteristicscanbefurtherdescribedinthreeimportantprinciples-roadisolation,roadholdingandcornering.Thetablebelowdescribestheseprinciplesandhowengineersattempttosolvethechallengesuniquetoeach.PrincipleDefinitionGoalSolutionRoadIsolationThevehicle'sabilitytoabsorborisolateroadshockfromthepassengercompartmentAllowthevehiclebodytorideundisturbedwhiletravelingoverroughroads.Absorbenergyfromroadbumpsanddissipate（驱散）itwithoutcausingundue（不恰当的）oscillation（振动）inthevehicle.RoadHoldingThedegreetowhichacarmaintainscontactwiththeroadsurfaceinvarioustypesofdirectionalchangesandinastraightline(Example:Theweightofacarwillshiftfromthereartirestothefronttiresduringbraking.Becausethenoseofthecardipstowardtheroad,thistypeofmotionisknownas"dive."Theoppositeeffect--"squat"--occursduringacceleration,whichshiftstheweightofthecarfromthefronttirestotheback.)Keepthetiresincontactwiththeground,becauseitisthefrictionbetweenthetiresandtheroadthataffectsavehicle'sabilitytosteer,brakeandaccelerate.Minimizethetransferofvehicleweightfromsidetosideandfronttoback,asthistransferofweightreducesthetire'sgripontheroad.CorneringTheabilityofavehicletotravelacurvedpathMinimizebodyroll,whichoccursascentrifugalforcepushesoutwardonacar'scenterofgravitywhilecornering,raisingonesideofthevehicleandloweringtheoppositeside.Transfertheweightofthecarduringcorneringfromthehighsideofthevehicletothelowside.Acar'ssuspension,withitsvariouscomponents,providesallofthesolutionsdescribed.Let'slookatthepartsofatypicalsuspension,workingfromthebiggerpictureofthechassisdowntotheindividualcomponentsthatmakeupthesuspensionproper.TheChassisThesuspensionofacarisactuallypartofthechassis,whichcomprisesalloftheimportantsystemslocatedbeneaththecar'sbody.ChassisThesesystemsinclude:Theframe-structural,load-carryingcomponentthatsupportsthecar'sengineandbody,whichareinturnsupportedbythesuspensionThesuspensionsystem-setupthatsupportsweight,absorbsanddampensshockandhelpsmaintaintirecontactThesteeringsystem-mechanismthatenablesthedrivertoguideanddirectthevehicleThetiresandwheels-componentsthatmakevehiclemotionpossiblebywayofgripand/orfrictionwiththeroadSothesuspensionisjustoneofthemajorsystemsinanyvehicle.Withthisbig-pictureoverviewinmind,it'stimetolookatthethreefundamentalcomponentsofanysuspension:springs,dampersandanti-swaybars.SpringsToday'sspringingsystemsarebasedononeoffourbasicdesigns:Coilsprings-Thisisthemostcommontypeofspringandis,inessence,aheavy-dutytorsionbarcoiledaroundanaxis.Coilspringscompressandexpandtoabsorbthemotionofthewheels.PhotocourtesyHYPERLINK"http://auto.howstuffworks.com/framed.htm?parent=car-suspension.htm&url=http://www.cardomain.com"CarDomainCoilspringsPhotocourtesyHYPERLINK"http://auto.howstuffworks.com/framed.htm?parent=car-suspension.htm&url=http://www.autopartswarehouse.com/pm/tokico~load_leaf_spring~bperformance.html?apwcid=M1092232155W411a23db5fb4c&apwkwd=Tokico+Load+Leaf+Spring"HowStuffWorksShopperLeafspringLeafsprings-Thistypeofspringconsistsofseverallayersofmetal(called"leaves")boundtogethertoactasasingleunit.Leafspringswerefirstusedonhorse-drawncarriagesandwerefoundonmostAmericanautomobilesuntil1985.Theyarestillusedtodayonmosttrucksandheavy-dutyvehicles.Torsionbars-Torsionbars（扭力杆）usethetwistingpropertiesofasteelbartoprovidecoil-spring-likeperformance.Thisishowtheywork:Oneendofabarisanchoredtothevehicleframe.Theotherendisattachedtoawishbone,whichactslikealeverthatmovesperpendiculartothetorsionbar.Whenthewheelhitsabump,verticalmotionistransferredtothewishboneandthen,throughtheleveringaction,tothetorsionbar.Thetorsionbarthentwistsalongitsaxistoprovidethespringforce.Europeancarmakersusedthissystemextensively,asdidPackardandChryslerintheUnitedStates,throughthe1950sand1960s.PhotocourtesyHYPERLINK"http://auto.howstuffworks.com/framed.htm?parent=car-suspension.htm&url=http://carpartsdiscount.zoovy.com/product/527788?meta=dealtime-527788"HowStuffWorksShopperTorsionbarAirsprings-Airsprings,whichconsistofacylindricalchamberofairpositionedbetweenthewheelandthecar'sbody,usethecompressivequalitiesofairtoabsorbwheelvibrations.Theconceptisactuallymorethanacenturyoldandcouldbefoundonhorse-drawnbuggies.Airspringsfromthiseraweremadefromair-filled,leatherdiaphragms,muchlikeabellows;theywerereplacedwithmolded-rubber（橡胶浇筑）airspringsinthe1930s.PhotocourtesyHYPERLINK""HSWShopperAirspringsBasedonwherespringsarelocatedonacar--i.e.,betweenthewheelsandtheframe--engineersoftenfinditconvenienttotalkaboutthesprungmassandtheunsprungmass.Springs:SprungandUnsprungMass（簧下质量）Thesprungmassisthemassofthevehiclesupportedonthesprings,whiletheunsprungmassislooselydefinedasthemassbetweentheroadandthesuspensionsprings.Thestiffnessofthespringsaffectshowthesprungmassrespondswhilethecarisbeingdriven.Looselysprungcars,suchasluxurycars(thinkHYPERLINK"http://auto.howstuffworks.com/framed.htm?parent=car-suspension.htm&url=http://www.lincoln.com/vehicles/towncar/default.asp?flash=1&feature=v410"LincolnTownCar),canswallowbumpsandprovideasuper-smoothride;however,suchacarispronetodiveandsquatduringbrakingandaccelerationandtendstoexperiencebodyswayorrollduringcornering.Tightlysprungcars,suchassportscars(thinkMazdaMiata),arelessforgivingonbumpyroads,buttheyminimizebodymotionwell,whichmeanstheycanbedrivenaggressively,evenaroundcorners.So,whilespringsbythemselvesseemlikesimpledevices,designingandimplementingthemonacartobalancepassengercomfortwithhandlingisacomplextask.Andtomakemattersmorecomplex,springsalonecan'tprovideaperfectlysmoothride.Why?Becausespringsaregreatatabsorbingenergy,butnotsogoodatdissipatingit.Otherstructures,knownasdampers,arerequiredtodothis.HistoricalSuspensionsSixteenth-centurywagonsandcarriagestriedtosolvetheproblemof"feelingeverybumpintheroad"byslingingthecarriagebodyfromleatherstrapsattachedtofourpostsofachassisthatlookedlikeanupturnedtable.Becausethecarriagebodywassuspendedfromthechassis,thesystemcametobeknownasa"suspension"--atermstillusedtodaytodescribetheentireclassofsolutions.Theslung-bodysuspensionwasnotatruespringingsystem,butitdidenablethebodyandthewheelsofthecarriagetomoveindependently.Semi-ellipticalspringdesigns,alsoknownascartsprings,quicklyreplacedtheleather-strapsuspension.Popularonwagons,buggiesandcarriages,thesemi-ellipticalspringswereoftenusedonboththefrontandrearaxles.Theydid,however,tendtoallowforwardandbackwardswayandhadahighcenterofgravity.Bythetimepoweredvehicleshittheroad,other,moreefficientspringingsystemswerebeingdevelopedtosmoothoutridesforpassengers.Dampers:ShockAbsorbersUnlessadampeningstructureispresent,acarspringwillextendandreleasetheenergyitabsorbsfromabumpatanuncontrolledrate.Thespringwillcontinuetobounce（反弹）atitsnaturalfrequencyuntilalloftheenergyoriginallyputintoitisusedup.Asuspensionbuiltonspringsalonewouldmakeforanextremelybouncyrideand,dependingontheterrain,anuncontrollablecar.Entertheshockabsorber,orsnubber（缓冲器）,adevicethatcontrolsunwantedspringmotionthroughaprocessknownasdampening.Shockabsorbersslowdownandreducethemagnitudeofvibratorymotionsbyturningthekineticenergy（动能）ofsuspensionmovementintoheatenergythatcanbedissipatedthroughhydraulicfluid.Tounderstandhowthisworks,it'sbesttolookinsideashockabsorbertoseeitsstructureandfunction.Ashockabsorberisbasicallyanoilpumpplacedbetweentheframeofthecarandthewheels.Theuppermountoftheshockconnectstotheframe(i.e.,thesprungweight),whilethelowermountconnectstotheaxle,nearthewheel(i.e.,theunsprungweight).Inatwin-tubedesign,oneofthemostcommontypesofshockabsorbers,theuppermountisconnectedtoapistonrod,whichinturnisconnectedtoapiston,whichinturnsitsinatubefilledwithhydraulicfluid.Theinnertubeisknownasthepressuretube,andtheoutertubeisknownasthereservetube.Thereservetubestoresexcesshydraulicfluid.Whenthecarwheelencountersabumpintheroadandcausesthespringtocoilanduncoil,theenergyofthespringistransferredtotheshockabsorberthroughtheuppermount,downthroughthepistonrodandintothepiston.Orificesperforatethepistonandallowfluidtoleakthroughasthepistonmovesupanddowninthepressuretube.Becausetheorificesarerelativelytiny,onlyasmallamountoffluid,undergreatpressure,passesthrough.Thisslowsdownthepiston,whichinturnslowsdownthespring.Shockabsorbersworkintwocycles--thecompressioncycleandtheextensioncycle.Thecompressioncycleoccursasthepistonmovesdownward,compressingthehydraulicfluidinthechamberbelowthepiston.Theextensioncycleoccursasthepistonmovestowardthetopofthepressuretube,compressingthefluidinthechamberabovethepiston.Atypicalcarorlighttruckwillhavemoreresistanceduringitsextensioncyclethanitscompressioncycle.Withthatinmind,thecompressioncyclecontrolsthemotionofthevehicle'sunsprungweight,whileextensioncontrolstheheavier,sprungweight.Allmodernshockabsorbersarevelocity-sensitive--thefasterthesuspensionmoves,themoreresistancetheshockabsorberprovides.Thisenablesshockstoadjusttoroadconditionsandtocontrolalloftheunwantedmotionsthatcanoccurinamovingvehicle,includingbounce,sway,brakediveandaccelerationsquat.Dampers:StrutsandAnti-swayBarsAnothercommondampeningstructureisthestrut--basicallyashockabsorbermountedinsideacoilspring.Strutsperformtwojobs:Theyprovideadampeningfunctionlikeshockabsorbers,andtheyprovidestructuralsupportforthevehiclesuspension.Thatmeansstrutsdeliverabitmorethanshockabsorbers,whichdon'tsupportvehicleweight--theyonlycontrolthespeedatwhichweightistransferredinacar,nottheweightitself.CommonstrutdesignBecauseshocksandstrutshavesomuchtodowiththehandlingofacar,theycanbeconsideredcriticalsafetyfeatures.Wornshocksandstrutscanallowexcessivevehicle-weighttransferfromsidetosideandfronttoback.ThisreducestheHYPERLINK"http://auto.howstuffworks.com/tire.htm"tire'sabilitytogriptheroad,aswellashandlingandHYPERLINK"http://auto.howstuffworks.com/brake.htm"brakingperformance.Anti-swayBars（稳定杆）Anti-swaybars(alsoknownasanti-rollbars)areusedalongwithshockabsorbersorstrutstogiveamovingautomobileadditionalstability.Ananti-swaybarisametalrodthatspanstheentireaxleandeffectivelyjoinseachsideofthesuspensiontogether.PhotocourtesyHYPERLINK"http://auto.howstuffworks.com/framed.htm?parent=car-suspension.htm&url=http://www.sportcompactonly.com/product.aspx?p=2214&c=55&st=53&l=2&utm_source=shopping&utm_medium=shop"HSWShopperAnti-swaybarsWhenthesuspensionatonewheelmovesupanddown,theanti-swaybartransfersmovementtotheotherwheel.Thiscreatesamorelevelrideandreducesvehiclesway.Inparticular,itcombatstherollofacaronitssuspensionasitcorners.Forthisreason,almostallcarstodayarefittedwithanti-swaybarsasstandardequipment,althoughifthey'renot,kitsmakeiteasytoinstallthebarsatanytime.SuspensionTypes:FrontSofar,ourdiscussionshavefocusedonhowspringsanddampersfunctiononanygivenwheel.Butthefourwheelsofacarworktogetherintwoindependentsystems--thetwowheelsconnectedbythefrontaxleandthetwowheelsconnectedbytherearaxle.Thatmeansthatacarcanandusuallydoeshaveadifferenttypeofsuspensiononthefrontandback.Muchisdeterminedbywhetherarigidaxlebindsthewheelsorifthewheelsarepermittedtomoveindependently.Theformerarrangementisknownasadependentsystem,whilethelatterarrangementisknownasanindependentsystem.Inthefollowingsections,we'lllookatsomeofthecommontypesoffrontandbacksuspensionstypicallyusedonmainstreamcars.FrontSuspension-DependentSystemsDependentfrontsuspensionshavearigidfrontaxlethatconnectsthefrontwheels.Basically,thislookslikeasolidbarunderthefrontofthecar,keptinplacebyleafspringsandshockabsorbers.Commonontrucks,dependentfrontsuspensionshaven'tbeenusedinmainstreamcarsforyears.FrontSuspension-IndependentSystemsInthissetup,thefrontwheelsareallowedtomoveindependently.TheMacPhersonstrut,developedbyEarleS.MacPhersonofGeneralMotorsin1947,isthemostwidelyusedfrontsuspensionsystem,especiallyincarsofEuropeanorigin.TheMacPhersonstrutcombinesashockabsorberandacoilspringintoasingleunit.Thisprovidesamorecompactandlightersuspensionsystemthatcanbeusedforfront-wheeldrivevehicles.Thedouble-wishbonesuspension,alsoknownasanA-armsuspension,isanothercommontypeoffrontindependentsuspension.PhotocourtesyHondaMotorCo.,Ltd.Double-wishbonesuspensiononHondaAccord2005CoupeWhilethereareseveraldifferentpossibleconfigurations,thisdesigntypicallyusestwowishbone-shapedarmstolocatethewheel.Eachwishbone,whichhastwomountingpositionstotheframeandoneatthewheel,bearsashockabsorberandacoilspringtoabsorbvibrations.Double-wishbonesuspensionsallowformorecontroloverthecamberangleofthewheel,whichdescribesthedegreetowhichthewheelstiltinandout.Theyalsohelpminimizerollorswayandprovideforamoreconsistentsteeringfeel.Becauseofthesecharacteristics,thedouble-wishbonesuspensioniscommononthefrontwheelsoflargercars.Nowlet'slookatsomecommonrearsuspensions.SuspensionTypes:RearRearSuspension-DependentSystemsPhotocourtesyHYPERLINK"http://auto.howstuffworks.com/framed.htm?parent=car-suspension.htm&url=http://www.autopartswarehouse.com/pm/tokico~load_leaf_spring~bperformance.html?apwcid=M1092232155W411a23db5fb4c&apwkwd=Tokico+Load+Leaf+Spring"HowStuffWorksShopperLeafspringIfasolidaxleconnectstherearwheelsofacar,thenthesuspensionisusuallyquitesimple--basedeitheronaleafspringoracoilspring.Intheformerdesign,theleafspringsclampdirectlytothedriveaxle.Theendsoftheleafspringsattachdirectlytotheframe,andtheshockabsorberisattachedattheclampthatholdsthespringtotheaxle.Formanyyears,Americancarmanufacturerspreferredthisdesignbecauseofitssimplicity.Thesamebasicdesigncanbeachievedwithcoilspringsreplacingtheleaves.Inthiscase,thespringandshockabsorbercanbemountedasasingleunitorasseparatecomponents.Whenthey'reseparate,thespringscanbemuchsmaller,whichreducestheamountofspacethesuspensiontakesup.RearSuspension-IndependentSuspensionsIfboththefrontandbacksuspensionsareindependent,thenallofthewheelsaremountedandsprungindividually,resultinginwhatcaradvertisementstoutas"four-wheelindependentsuspension."Anysuspensionthatcanbeusedonthefrontofthecarcanbeusedontherear,andversionsofthefrontindependentsystemsdescribedintheprevioussectioncanbefoundontherearaxles.Ofcourse,intherearofthecar,theHYPERLINK"http://auto.howstuffworks.com/steering2.htm"steeringrack--theassemblythatincludesthepiniongearwheelandenablesthewheelstoturnfromsidetoside--isabsent.Thismeansthatrearindependentsuspensionscanbesimplifiedversionsoffrontones,althoughthebasicprinciplesremainthesame.SpecializedSuspensions:TheBajaBugForthemostpart,thisarticlehasfocusedonthesuspensionsofmainstreamfront-andrear-wheel-drivecars--carsthatdriveonnormalroadsinnormaldrivingconditions.Butwhataboutthesuspensionsofspecialtycars,suchashotrods,racersorextremeoff-roadvehicles?Althoughthesuspensionsofspecialtyautosobeythesamebasicprinciples,theydoprovideadditionalbenefitsuniquetothedrivingconditionstheymustnavigate.Whatfollowsisabriefoverviewofhowsuspensionsaredesignedforthreetypesofspecialtycars--BajaBugs,FormulaOneracersandAmerican-stylehotrods.BajaBugsTheVolkswagenBeetleorBugwasdestinedtobecomeafavoriteamongoff-roadenthusiasts.Withalowcenterofgravityandengineplacementovertherearaxle,thetwo-wheel-driveBughandlesoff-roadconditionsaswellassomeHYPERLINK"http://auto.howstuffworks.com/four-wheel-drive.htm"four-wheel-drivevehicles.Ofcourse,theVWBugisn'treadyforoff-roadconditionswithitsfactoryequipment.MostBugsrequiresomemodifications,orconversions,togetthemreadyforracinginharshconditionslikethedesertsofBajaCalifornia.PhotocourtesyHYPERLINK"http://auto.howstuffworks.com/framed.htm?parent=car-suspension.htm&url=http://www.cardomain.com"CarDomainBajaBugOneofthemostimportantmodificationstakesplaceinthesuspension.Thetorsion-barsuspension,standardequipmentonthefrontandbackofmostBugsbetween1936and1977,canberaisedtomakeroomforheavy-duty,off-roadwheelsandtires.Longershockabsorbersreplacethestandardshockstoliftthebodyhigherandtoprovideformaximumwheeltravel.Insomecases,BajaBugconvertersremovethetorsionbarsentirelyandreplacethemwithmultiplecoil-oversystems,anaftermarketitemthatcombinesboththespringandshockabsorberinoneadjustableunit.Theresultofthesemodificationsisavehiclethatallowsthewheelstotravelvertically20inches(50cm)ormoreateachend.Suchacarcaneasilynavigateroughterrainandoftenappearsto"skip"overdesertwashboardlikeastoneoverwater.SpecializedSuspensions:FormulaOneRacersTheFormulaOneracingcarrepresentsthepinnacleofautomobileinnovationandevolution.Lightweight,compositebodies,powerfulV10enginesandadvancedaerodynamicshaveledtofaster,saferandmorereliablecars.FormulaOneracecarToelevatedriverskillasthekeydifferentiatingfactorinarace,stringentrulesandrequirementsgovernFormulaOneracecardesign.Forexample,therulesregulatingsuspensiondesignsaythatallFormulaOneracersmustbeconventionallysprung,buttheydon'tallowcomputer-controlled,activesuspensions.Toaccommodatethis,thecarsfeaturemulti-linksuspensions,whichuseamulti-rodmechanismequivalenttoadouble-wishbonesystem.Recallthatadouble-wishbonedesignusestwowishbone-shapedcontrolarmstoguideeachwheel'sup-and-downmotion.Eacharmhasthreemountingpositions--twoattheframeandoneatthewheelhub--andeachjointishingedtoguidethewheel'smotion.Inallcars,theprimarybenefitofadouble-wishbonesuspensioniscontrol.Thegeometryofthearmsandtheelasticityofthejointsgiveengineersultimatecontrolovertheangleofthewheelandothervehicledynamics,suchaslift,squatanddive.Unlikeroadcars,however,theshockabsorbersandcoilspringsofaFormulaOneracecardon'tmountdirectlytothecontrolarms.Instead,theyareorientedalongthelengthofthecarandarecontrolledremotelythroughaseriesofpushrodsandbellcranks.Insuchanarrangement,thepushrodsandbellcrankstranslatetheup-and-downmotionsofthewheeltotheback-and-forthmovementofthespring-and-damperapparatus.SpecializedSuspensions:HotRodsTheclassicAmericanhotroderalastedfrom1945toab