已阅读5页,还剩6页未读, 继续免费阅读
版权说明:本文档由用户提供并上传,收益归属内容提供方,若内容存在侵权,请进行举报或认领
文档简介
英文资料SuspensionSuspensionisthetermgiventothesystemofsprings,shockabsorbersandlinkagesthatconnectsavehicletoitswheels.Suspensionsystemsserveadualpurposecontributingtothecarsroadholding/handlingandbrakingforgoodactivesafetyanddrivingpleasure,andkeepingvehicleoccupantscomfortableandreasonablywellisolatedfromroadnoise,bumps,andvibrations,etc.Thesegoalsaregenerallyatodds,sothetuningofsuspensionsinvolvesfindingtherightcompromise.Itisimportantforthesuspensiontokeeptheroadwheelincontactwiththeroadsurfaceasmuchaspossible,becausealltheforcesactingonthevehicledosothroughthecontactpatchesofthetires.Thesuspensionalsoprotectsthevehicleitselfandanycargoorluggagefromdamageandwear.Thedesignoffrontandrearsuspensionofacarmaybedifferent.LeafspringshavebeenaroundsincetheearlyEgyptians.Ancientmilitaryengineersusedleafspringsintheformofbowstopowertheirsiegeengines,withlittlesuccessatfirst.Theuseofleafspringsincatapultswaslaterrefinedandmadetoworkyearslater.Springswerenotonlymadeofmetal,asturdytreebranchcouldbeusedasaspring,suchaswithabow.HorsedrawnvehiclesBytheearly19thcenturymostBritishhorsecarriageswereequippedwithsprings;woodenspringsinthecaseoflightone-horsevehiclestoavoidtaxation,andsteelspringsinlargervehicles.Theseweremadeoflow-carbonsteelandusuallytooktheformofmultiplelayerleafsprings.1TheBritishsteelspringswerenotwellsuitedforuseonAmericasroughroadsofthetime,andcouldevencausecoachestocollapseifcorneredtoofast.Inthe1820s,theAbbotDowningCompanyofConcord,NewHampshiredevelopedasystemwherebythebodiesofstagecoachesweresupportedonleatherstrapscalledthoroughbraces,whichgaveaswingingmotioninsteadofthejoltingupanddownofaspringsuspension(thestagecoachitselfwassometimescalledathoroughbrace)AutomobilesAutomobileswereinitiallydevelopedasself-propelledversionsofhorsedrawnvehicles.However,horsedrawnvehicleshadbeendesignedforrelativelyslowspeedsandtheirsuspensionwasnotwellsuitedtothehigherspeedspermittedbytheinternalcombustionengine.In1903MorsofGermanyfirstfittedanautomobilewithshockabsorbers.In1920Leylandusedtorsionbarsinasuspensionsystem.In1922independentfrontsuspensionwaspioneeredontheLanciaLambdaandbecamemorecommoninmassmarketcarsfrom1932.2ImportantpropertiesSpringrateThespringrate(orsuspensionrate)isacomponentinsettingthevehiclesrideheightoritslocationinthesuspensionstroke.Vehicleswhichcarryheavyloadswilloftenhaveheavierspringstocompensatefortheadditionalweightthatwouldotherwisecollapseavehicletothebottomofitstravel(stroke).Heavierspringsarealsousedinperformanceapplicationswheretheloadingconditionsexperiencedaremoreextreme.Springsthataretoohardortoosoftcausethesuspensiontobecomeineffectivebecausetheyfailtoproperlyisolatethevehiclefromtheroad.Vehiclesthatcommonlyexperiencesuspensionloadsheavierthannormalhaveheavyorhardspringswithaspringrateclosetotheupperlimitforthatvehiclesweight.Thisallowsthevehicletoperformproperlyunderaheavyloadwhencontrolislimitedbytheinertiaoftheload.Ridinginanemptytruckusedforcarryingloadscanbeuncomfortableforpassengersbecauseofitshighspringraterelativetotheweightofthevehicle.Aracecarwouldalsobedescribedashavingheavyspringsandwouldalsobeuncomfortablybumpy.However,eventhoughwesaytheybothhaveheavysprings,theactualspringratesfora2000lbracecaranda10,000lbtruckareverydifferent.Aluxurycar,taxi,orpassengerbuswouldbedescribedashavingsoftsprings.Vehicleswithwornoutordamagedspringsridelowertothegroundwhichreducestheoverallamountofcompressionavailabletothesuspensionandincreasestheamountofbodylean.Performancevehiclescansometimeshavespringraterequirementsotherthanvehicleweightandload.MathematicsofthespringrateSpringrateisaratiousedtomeasurehowresistantaspringistobeingcompressedorexpandedduringthespringsdeflection.ThemagnitudeofthespringforceincreasesasdeflectionincreasesaccordingtoHookesLaw.Briefly,thiscanbestatedaswhereFistheforcethespringexertskisthespringrateofthespring.xisthedisplacementfromequilibriumlengthi.e.thelengthatwhichthespringisneithercompressedorstretched.Springrateisconfinedtoanarrowintervalbytheweightofthevehicle,loadthevehiclewillcarry,andtoalesserextentbysuspensiongeometryandperformancedesires.SpringratestypicallyhaveunitsofN/mm(orlbf/in).Anexampleofalinearspringrateis500lbf/in.Foreveryinchthespringiscompressed,itexerts500lbf.Anon-linearspringrateisoneforwhichtherelationbetweenthespringscompressionandtheforceexertedcannotbefittedadequatelytoalinearmodel.Forexample,thefirstinchexerts500lbfforce,thesecondinchexertsanadditional550lbf(foratotalof1050lbf),thethirdinchexertsanother600lbf(foratotalof1650lbf).Incontrasta500lbf/inlinearspringcompressedto3incheswillonlyexert1500lbf.Thespringrateofacoilspringmaybecalculatedbyasimplealgebraicequationoritmaybemeasuredinaspringtestingmachine.Thespringconstantkcanbecalculatedasfollows:wheredisthewirediameter,Gisthespringsshearmodulus(e.g.,about12,000,000lbf/inor80GPaforsteel),andNisthenumberofwrapsandDisthediameterofthecoil.WheelrateWheelrateistheeffectivespringratewhenmeasuredatthewheel.Thisisasopposedtosimplymeasuringthespringratealone.Wheelrateisusuallyequaltoorconsiderablylessthanthespringrate.Commonly,springsaremountedoncontrolarms,swingarmsorsomeotherpivotingsuspensionmember.Considertheexampleabovewherethespringratewascalculatedtobe500lbs/inch,ifyouweretomovethewheel1inch(withoutmovingthecar),thespringmorethanlikelycompressesasmalleramount.Letsassumethespringmoved0.75inches,theleverarmratiowouldbe0.75to1.Thewheelrateiscalculatedbytakingthesquareoftheratio(0.5625)timesthespringrate.Squaringtheratioisbecausetheratiohastwoeffectsonthewheelrate.Theratioappliestoboththeforceanddistancetraveled.Wheelrateonindependentsuspensionisfairlystraight-forward.However,specialconsiderationmustbetakenwithsomenon-independentsuspensiondesigns.Takethecaseofthestraightaxle.Whenviewedfromthefrontorrear,thewheelratecanbemeasuredbythemeansabove.Yetbecausethewheelsarenotindependent,whenviewedfromthesideunderaccelerationorbrakingthepivotpointisatinfinity(becausebothwheelshavemoved)andthespringisdirectlyinlinewiththewheelcontactpatch.Theresultisoftenthattheeffectivewheelrateundercorneringisdifferentfromwhatitisunderaccelerationandbraking.Thisvariationinwheelratemaybeminimizedbylocatingthespringasclosetothewheelaspossible.RollcouplepercentageRollcouplepercentageistheeffectivewheelrates,inroll,ofeachaxleofthevehiclejustasaratioofthevehiclestotalrollrate.RollCouplePercentageiscriticalinaccuratel
温馨提示
- 1. 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
- 2. 本站的文档不包含任何第三方提供的附件图纸等,如果需要附件,请联系上传者。文件的所有权益归上传用户所有。
- 3. 本站RAR压缩包中若带图纸,网页内容里面会有图纸预览,若没有图纸预览就没有图纸。
- 4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
- 5. 人人文库网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对用户上传分享的文档内容本身不做任何修改或编辑,并不能对任何下载内容负责。
- 6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
- 7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
最新文档
- 企业员工获奖感言集锦(12篇)
- 2024年高等教育经济类自考-06069审计学原理笔试历年真题荟萃含答案
- 2023年高强度超声聚焦肿瘤治疗系统项目概述报告
- 2024年02月重庆中医药学院招考聘用笔试近6年高频考题难、易错点荟萃答案带详解附后
- 2024年02月湖北省红安县事业单位2024年统一公开招考101名工作人员笔试近6年高频考题难、易错点荟萃答案带详解附后
- 2024年02月浙江省嘉兴市事业单位和国有企业2024年公开招考216名高层次人才笔试近6年高频考题难、易错点荟萃答案带详解附后
- 2024年02月河南郑州大学第五附属医院招考聘用博士-硕士工作人员115人笔试近6年高频考题难、易错点荟萃答案带详解附后
- 2024年02月广西上思县2024年度公开招考142名事业单位工作人员笔试近6年高频考题难、易错点荟萃答案带详解附后
- 2024年02月山东东营市属事业单位选聘202人笔试近6年高频考题难、易错点荟萃答案带详解附后
- 2024年02月天津市老干部活动中心(天津市老年活动中心)招考聘用笔试近6年高频考题难、易错点荟萃答案带详解附后
- sat数学考试试题
- 高中政治选修一第二单元 世界多极化 知识提纲(核心知识点)-
- 食品添加剂知识讲座
- 小学英语川教五年级上册MeCrazyCatHelpsOut教学设计
- 微课在课堂中的运用研究课件
- 英语基本句子结构课件
- 免疫室工作记录
- 医学影像成像理论第三章 模拟X线成像第三节 X线照片影像的基本要素
- 《水资源的利用与保护》-完整版获奖课件
- 河道治理表格
- 武汉市历年中考数学试卷,2014-2021年武汉市中考数学近八年真题汇总(含答案解析)
评论
0/150
提交评论