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英文资料SUSPENSIONSUSPENSIONISTHETERMGIVENTOTHESYSTEMOFSPRINGS,SHOCKABSORBERSANDLINKAGESTHATCONNECTSAVEHICLETOITSWHEELSSUSPENSIONSYSTEMSSERVEADUALPURPOSE–CONTRIBUTINGTOTHECARSROADHOLDING/HANDLINGANDBRAKINGFORGOODACTIVESAFETYANDDRIVINGPLEASURE,ANDKEEPINGVEHICLEOCCUPANTSCOMFORTABLEANDREASONABLYWELLISOLATEDFROMROADNOISE,BUMPS,ANDVIBRATIONS,ETCTHESEGOALSAREGENERALLYATODDS,SOTHETUNINGOFSUSPENSIONSINVOLVESFINDINGTHERIGHTCOMPROMISEITISIMPORTANTFORTHESUSPENSIONTOKEEPTHEROADWHEELINCONTACTWITHTHEROADSURFACEASMUCHASPOSSIBLE,BECAUSEALLTHEFORCESACTINGONTHEVEHICLEDOSOTHROUGHTHECONTACTPATCHESOFTHETIRESTHESUSPENSIONALSOPROTECTSTHEVEHICLEITSELFANDANYCARGOORLUGGAGEFROMDAMAGEANDWEARTHEDESIGNOFFRONTANDREARSUSPENSIONOFACARMAYBEDIFFERENTLEAFSPRINGSHAVEBEENAROUNDSINCETHEEARLYEGYPTIANSANCIENTMILITARYENGINEERSUSEDLEAFSPRINGSINTHEFORMOFBOWSTOPOWERTHEIRSIEGEENGINES,WITHLITTLESUCCESSATFIRSTTHEUSEOFLEAFSPRINGSINCATAPULTSWASLATERREFINEDANDMADETOWORKYEARSLATERSPRINGSWERENOTONLYMADEOFMETAL,ASTURDYTREEBRANCHCOULDBEUSEDASASPRING,SUCHASWITHABOWHORSEDRAWNVEHICLESBYTHEEARLY19THCENTURYMOSTBRITISHHORSECARRIAGESWEREEQUIPPEDWITHSPRINGS；WOODENSPRINGSINTHECASEOFLIGHTONEHORSEVEHICLESTOAVOIDTAXATION,ANDSTEELSPRINGSINLARGERVEHICLESTHESEWEREMADEOFLOWCARBONSTEELANDUSUALLYTOOKTHEFORMOFMULTIPLELAYERLEAFSPRINGS1THEBRITISHSTEELSPRINGSWERENOTWELLSUITEDFORUSEONAMERICASROUGHROADSOFTHETIME,ANDCOULDEVENCAUSECOACHESTOCOLLAPSEIFCORNEREDTOOFASTINTHE1820S,THEABBOTDOWNINGCOMPANYOFCONCORD,NEWHAMPSHIREDEVELOPEDASYSTEMWHEREBYTHEBODIESOFSTAGECOACHESWERESUPPORTEDONLEATHERSTRAPSCALLEDTHOROUGHBRACES,WHICHGAVEASWINGINGMOTIONINSTEADOFTHEJOLTINGUPANDDOWNOFASPRINGSUSPENSIONTHESTAGECOACHITSELFWASSOMETIMESCALLEDATHOROUGHBRACEAUTOMOBILESAUTOMOBILESWEREINITIALLYDEVELOPEDASSELFPROPELLEDVERSIONSOFHORSEDRAWNVEHICLESHOWEVER,HORSEDRAWNVEHICLESHADBEENDESIGNEDFORRELATIVELYSLOWSPEEDSANDTHEIRSUSPENSIONWASNOTWELLSUITEDTOTHEHIGHERSPEEDSPERMITTEDBYTHEINTERNALCOMBUSTIONENGINEIN1903MORSOFGERMANYFIRSTFITTEDANAUTOMOBILEWITHSHOCKABSORBERSIN1920LEYLANDUSEDTORSIONBARSINASUSPENSIONSYSTEMIN1922INDEPENDENTFRONTSUSPENSIONWASPIONEEREDONTHELANCIALAMBDAANDBECAMEMORECOMMONINMASSMARKETCARSFROM19322IMPORTANTPROPERTIESSPRINGRATETHESPRINGRATEORSUSPENSIONRATEISACOMPONENTINSETTINGTHEVEHICLESRIDEHEIGHTORITSLOCATIONINTHESUSPENSIONSTROKEVEHICLESWHICHCARRYHEAVYLOADSWILLOFTENHAVEHEAVIERSPRINGSTOCOMPENSATEFORTHEADDITIONALWEIGHTTHATWOULDOTHERWISECOLLAPSEAVEHICLETOTHEBOTTOMOFITSTRAVELSTROKEHEAVIERSPRINGSAREALSOUSEDINPERFORMANCEAPPLICATIONSWHERETHELOADINGCONDITIONSEXPERIENCEDAREMOREEXTREMESPRINGSTHATARETOOHARDORTOOSOFTCAUSETHESUSPENSIONTOBECOMEINEFFECTIVEBECAUSETHEYFAILTOPROPERLYISOLATETHEVEHICLEFROMTHEROADVEHICLESTHATCOMMONLYEXPERIENCESUSPENSIONLOADSHEAVIERTHANNORMALHAVEHEAVYORHARDSPRINGSWITHASPRINGRATECLOSETOTHEUPPERLIMITFORTHATVEHICLESWEIGHTTHISALLOWSTHEVEHICLETOPERFORMPROPERLYUNDERAHEAVYLOADWHENCONTROLISLIMITEDBYTHEINERTIAOFTHELOADRIDINGINANEMPTYTRUCKUSEDFORCARRYINGLOADSCANBEUNCOMFORTABLEFORPASSENGERSBECAUSEOFITSHIGHSPRINGRATERELATIVETOTHEWEIGHTOFTHEVEHICLEARACECARWOULDALSOBEDESCRIBEDASHAVINGHEAVYSPRINGSANDWOULDALSOBEUNCOMFORTABLYBUMPYHOWEVER,EVENTHOUGHWESAYTHEYBOTHHAVEHEAVYSPRINGS,THEACTUALSPRINGRATESFORA2000LBRACECARANDA10,000LBTRUCKAREVERYDIFFERENTALUXURYCAR,TAXI,ORPASSENGERBUSWOULDBEDESCRIBEDASHAVINGSOFTSPRINGSVEHICLESWITHWORNOUTORDAMAGEDSPRINGSRIDELOWERTOTHEGROUNDWHICHREDUCESTHEOVERALLAMOUNTOFCOMPRESSIONAVAILABLETOTHESUSPENSIONANDINCREASESTHEAMOUNTOFBODYLEANPERFORMANCEVEHICLESCANSOMETIMESHAVESPRINGRATEREQUIREMENTSOTHERTHANVEHICLEWEIGHTANDLOADMATHEMATICSOFTHESPRINGRATESPRINGRATEISARATIOUSEDTOMEASUREHOWRESISTANTASPRINGISTOBEINGCOMPRESSEDOREXPANDEDDURINGTHESPRINGSDEFLECTIONTHEMAGNITUDEOFTHESPRINGFORCEINCREASESASDEFLECTIONINCREASESACCORDINGTOHOOKESLAWBRIEFLY,THISCANBESTATEDASWHEREFISTHEFORCETHESPRINGEXERTSKISTHESPRINGRATEOFTHESPRINGXISTHEDISPLACEMENTFROMEQUILIBRIUMLENGTHIETHELENGTHATWHICHTHESPRINGISNEITHERCOMPRESSEDORSTRETCHEDSPRINGRATEISCONFINEDTOANARROWINTERVALBYTHEWEIGHTOFTHEVEHICLE,LOADTHEVEHICLEWILLCARRY,ANDTOALESSEREXTENTBYSUSPENSIONGEOMETRYANDPERFORMANCEDESIRESSPRINGRATESTYPICALLYHAVEUNITSOFN/MMORLBF/INANEXAMPLEOFALINEARSPRINGRATEIS500LBF/INFOREVERYINCHTHESPRINGISCOMPRESSED,ITEXERTS500LBFANONLINEARSPRINGRATEISONEFORWHICHTHERELATIONBETWEENTHESPRINGSCOMPRESSIONANDTHEFORCEEXERTEDCANNOTBEFITTEDADEQUATELYTOALINEARMODELFOREXAMPLE,THEFIRSTINCHEXERTS500LBFFORCE,THESECONDINCHEXERTSANADDITIONAL550LBFFORATOTALOF1050LBF,THETHIRDINCHEXERTSANOTHER600LBFFORATOTALOF1650LBFINCONTRASTA500LBF/INLINEARSPRINGCOMPRESSEDTO3INCHESWILLONLYEXERT1500LBFTHESPRINGRATEOFACOILSPRINGMAYBECALCULATEDBYASIMPLEALGEBRAICEQUATIONORITMAYBEMEASUREDINASPRINGTESTINGMACHINETHESPRINGCONSTANTKCANBECALCULATEDASFOLLOWSWHEREDISTHEWIREDIAMETER,GISTHESPRINGSSHEARMODULUSEG,ABOUT12,000,000LBF/INOR80GPAFORSTEEL,ANDNISTHENUMBEROFWRAPSANDDISTHEDIAMETEROFTHECOILWHEELRATEWHEELRATEISTHEEFFECTIVESPRINGRATEWHENMEASUREDATTHEWHEELTHISISASOPPOSEDTOSIMPLYMEASURINGTHESPRINGRATEALONEWHEELRATEISUSUALLYEQUALTOORCONSIDERABLYLESSTHANTHESPRINGRATECOMMONLY,SPRINGSAREMOUNTEDONCONTROLARMS,SWINGARMSORSOMEOTHERPIVOTINGSUSPENSIONMEMBERCONSIDERTHEEXAMPLEABOVEWHERETHESPRINGRATEWASCALCULATEDTOBE500LBS/INCH,IFYOUWERETOMOVETHEWHEEL1INCHWITHOUTMOVINGTHECAR,THESPRINGMORETHANLIKELYCOMPRESSESASMALLERAMOUNTLETSASSUMETHESPRINGMOVED075INCHES,THELEVERARMRATIOWOULDBE075TO1THEWHEELRATEISCALCULATEDBYTAKINGTHESQUAREOFTHERATIO05625TIMESTHESPRINGRATESQUARINGTHERATIOISBECAUSETHERATIOHASTWOEFFECTSONTHEWHEELRATETHERATIOAPPLIESTOBOTHTHEFORCEANDDISTANCETRAVELEDWHEELRATEONINDEPENDENTSUSPENSIONISFAIRLYSTRAIGHTFORWARDHOWEVER,SPECIALCONSIDERATIONMUSTBETAKENWITHSOMENONINDEPENDENTSUSPENSIONDESIGNSTAKETHECASEOFTHESTRAIGHTAXLEWHENVIEWEDFROMTHEFRONTORREAR,THEWHEELRATECANBEMEASUREDBYTHEMEANSABOVEYETBECAUSETHEWHEELSARENOTINDEPENDENT,WHENVIEWEDFROMTHESIDEUNDERACCELERATIONORBRAKINGTHEPIVOTPOINTISATINFINITYBECAUSEBOTHWHEELSHAVEMOVEDANDTHESPRINGISDIRECTLYINLINEWITHTHEWHEELCONTACTPATCHTHERESULTISOFTENTHATTHEEFFECTIVEWHEELRATEUNDERCORNERINGISDIFFERENTFROMWHATITISUNDERACCELERATIONANDBRAKINGTHISVARIATIONINWHEELRATEMAYBEMINIMIZEDBYLOCATINGTHESPRINGASCLOSETOTHEWHEELASPOSSIBLEROLLCOUPLEPERCENTAGEROLLCOUPLEPERCENTAGEISTHEEFFECTIVEWHEELRATES,INROLL,OFEACHAXLEOFTHEVEHICLEJUSTASARATIOOFTHEVEHICLESTOTALROLLRATEROLLCOUPLEPERCENTAGEISCRITICALINACCURATELYBALANCINGTHEHANDLINGOFAVEHICLEITISCOMMONLYADJUSTEDTHROUGHTHEUSEOFANTIROLLBARS,BUTCANALSOBECHANGEDTHROUGHTHEUSEOFDIFFERENTSPRINGSAVEHICLEWITHAROLLCOUPLEPERCENTAGEOF70WILLTRANSFER70OFITSSPRUNGWEIGHTTRANSFERATTHEFRONTOFTHEVEHICLEDURINGCORNERINGTHISISALSOCOMMONLYKNOWNASTOTALLATERALLOADTRANSFERDISTRIBUTIONORTLLTDWEIGHTTRANSFERWEIGHTTRANSFERDURINGCORNERING,ACCELERATIONORBRAKINGISUSUALLYCALCULATEDPERINDIVIDUALWHEELANDCOMPAREDWITHTHESTATICWEIGHTSFORTHESAMEWHEELSTHETOTALAMOUNTOFWEIGHTTRANSFERISONLYAFFECTEDBY4FACTORSTHEDISTANCEBETWEENWHEELCENTERSWHEELBASEINTHECASEOFBRAKING,ORTRACKWIDTHINTHECASEOFCORNERINGTHEHEIGHTOFTHECENTEROFGRAVITY,THEMASSOFTHEVEHICLE,ANDTHEAMOUNTOFACCELERATIONEXPERIENCED
