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
英文原文HowCarSuspensionWorkByWilliamHarrisUniversityofMichiganWhenpeoplethinlyofautomobileperformance,theynormallythinkofhorsepower,torqueandzero-to-60acceleration.Butallofthepowergeneratedbyapistonengineisuselessifthedriercantcontrolthecar.Thatswhyautomobileengineersturnedtheirattentiontothesuspensionsystemalmostassoonastheyhadmasteredthefour-Strokeinternalcombustionengine.Double-wishbonesuspensiononHondaAccord2005CoupeThejobofacarsuspensionistomaximizethefrictionbetweenthetiresandtheroadsurface,toprovidesteeringstabilitywithgoodhandlingandtoensurethecomfortofthepassengers.Inthisarticle,wellexplorehowcarSuspensionswork,howtheyreevolvedovertheyearsandwherethedesignofsuspensionsisheadedinthefuture.1.VehicleDynamicsIfaroadwereperfectlyt1at,withnoirregularities,suspensionswouldntbenecessary.Butroadsarefarfromt1at.Evenfreshlypavedhighwayshavesubtleimperfectionsthatcaninteractwiththewheelsofacar.Itstheseimperfectionsthatapplyforcestothewheels.AccordingtoNewtonslawsofmotion,allforceshavebothmagnitudeanddirection.Abumpintheroadcausesthewheeltomoveupanddownperpendiculartotheroadsurface.Themagnitude,ofcourse,dependsonwhetherthewheelisStrikingagiantbumporatinyspeck.Eitherway,theca.rwheelexperiencesaverticalaccelerationasitpassesoveranimperfection.Withoutaninterveningstructure,allofwheelsverticalenergyistransferredtotheframe,whichmovesintheSamedirection.Insuchasituation,thewheelscanlosecontactwiththeroadcompletely.Then,underthedownwardforceofgravity,wheelscanslambackintotheroadsurface.Whatyouneedisasystemthatabsorbtheenergyoftheverticallyacceleratedwheel,allowingtheframeandbodytorideundisturbedwhilethewheelsfollowbumpsintheroad.TheStudyofthefarcesatworkanamovingcariscalledvehicledynamics,andyouneedtosuspensionisnecessaryofneedtounderstandsameoftheseconceptsinordertoappreciatewhyanecessaryinthefirstplace.MastautomobileengineersconsiderthemovingcarPramtwoperspectives:1)Ride-acarsabilitytosmoothoutabumpyroad2)Handling-acarsabilitytosafelyaccelerate,brakeandcornerThesetwocharacteristicscanbefurtherdescribedinthreeimportantprinciples-roadisolation,roadholdingandcornering.Thetablebelowdescribestheseprinciplesandhowengineersattempttosolvethechallengesuniquetoeach.Acarssuspension,withitsvariouscomponents,providesalloftheSolutionsdescribed.2.TheChassisSystemThesuspensionofacarisactuallypartofthechassis,whichcomprisesalloftheimportantsystemslocatedbeneaththecarsbody.figure2-1ChassisThesesystemsinclude:1)Theframe-structural,load-carryingcomponentthatsupportsthecarsengineandbody,whichareinturnsupportedbythesuspension2)TheSuspensionsystem-setupthatsupportsweight,absorbsanddampensshockandhelpsmaintaintirecontact3)Thesteeringsystem-mechanismthatenablesthedrivertoguideanddirectthevehicle4)Thetiresandwheels-componentsthatmakevehiclemotionpossiblebywayofgripand/orfrictionwiththeroadSothesuspensionisjustoneofthemajorsystemsinanyvehicle.Withthisbig-pictureoverviewinmind,itstimetolookatthethreefundamentalcomponentsofanysuspension:springs,dampersandanti-swaybars.3.springsTodaysspringingsystemsarebasedononeoffourbasicdesign:1)Coilspring-Thisisthemastcommontypeofspringandis,inessence,aheavy-dutytorsionbarcoiledaroundanaxis.Coilspringscompressandexpandtoabsorbthemotionofthewheels.2)Leafspring-Thistypeofspringconsistsofseverallayersofmetal(calledleaves)boundtogethertoactasasingleunit.Leafspringswerefirstusedonhorse-drawncarriagesandwerefoundanmostAmericanautomobilesuntil1985.Theyarestillusedtodayonmosttrucksandheavy-dutyvehicles.3)Torsionbars-TorsionbarsusethetwistingpropertiesofasteelGartoprovidecoil-spring-likeperformance.Thisishowtheywork:Oneendofabarisanchoredtothevehicleframe.Theotherendi5attachedtoawishbone,whichactslikealeverthatmaresperpendiculartothetorsionbar.Whenthewheelhitsabump,verticalmotionistransferredtothewishboneandthen,throughtheleveringaction,tothetorsionbar.Thetorsionbarthentwistsalongitsaxistoprovidethespringfarce.Europeancaretakersusedthissystemextensively,asdidPackardandChryslerintheUnitedStates,throughthe1950sand1960s.4)Airsprings-AirSprings,whichconsistofacylindricalchamberofairpositionedbetweenthewheelandthecarsbody,usethecompres5irequalitiesofairtoabsorbwheelvibrations.Theconceptisactuallymorethanacenturyoldandcouldbefoundanhorse-drawnbuggies.Airspringsfromthiseraweremadefromair-filled,leatherdiaphragms,muchlikeabellows;theywerereplacedwithmolded-rubberairspringsinthe1930s.Basedonwherespringsarelocatedonacar-i.e.,betweenthewheelsandtheframe-engineersoftenfinditconvenienttotalkaboutthesprungmassandtheunsprungmass.4.SprungandUnsprungMassThesprungmassisthemassofthevehiclesupportedanthesprings,whiletheunsprungmassislooselydefinedasthemassbetweentheroadandthesuspensionSprings.Thestiffnessofthespringsaffectshowthesprungmassrespondswhilethecarisbeingdriven.Looselysprungcars,suchasluxurycarsthinkLincolnTawsCard,canSwallowbumpsandprovideasuper-smoothride;however,suchacarisprunetodiveandsquatduringbrakingandaccelerationandtendstoexperiencebodyawayorrollduringcornering.Tightlysprungcars,suchassportscars(thinkMazdaMiata),arelessforgivingonbumpyroads,buttheyminimizebodymotionwell,whichmeanstheycanbedrivenaggressively,evenaroundcorners.So,whilespringsbythemselvesseemlikesimpledevices,designingandimplementingthemonacartobalancepassengercomfortwithhandlingisacomplextask.Andtomakemattersmorecomplex,springsalonecantprovideaperfectlysmoothride.Why?BecauseSpringsaregreatatabsorbingenergy,butnotsogoodatdissipatingit.Otherstructures,knownasdampers,arerequiredtodothis.5.ShackAbsorbersUnlessadampeningstructureispresent,acarspringwillextendandreleasetheenergyitabsorbsfromabumpatanuncontrolledrate.Thespringwillcontinuetobounceatitsnaturalfrequencyuntilalloftheenergyoriginallyputintoitisusedup.Asuspensionbuiltanspringsalonewouldmakeforanextremelybouncyrideand,dependingantheterrain,anuncontrollablecar.Entertheshackabsorber,orsnubber,adevicethatcontrolsunwantedspringmotionthroughaprocessknownasdampening.Shockabsorbersslowdownandreducethemagnitudeofvibratorymotionsbyturningthekineticenergyofsuspensionmovementintoheatenergythatcanliedissipatedthroughhydraulicfluid.Tounderstandhowthisworks,itsbesttolookinsideashackabsorbertoseeitsstructureandfunction.Ashockabsorberisbasicallyanoilpumpplacedbetweentheframeofthecarandthewheels.Theuppermountoftheshockconnectstotheframe(i.e.,thesprungweight),whilethelowermountconnectstotheaxle,nearthewheel(i.e.,theunsprungweight).Inatwin-tubedesign,oneofthemostcommontypesofshock)absorbers,theuppermountisconnectedtoapistonrod,whichinturnisconnectedtoapiston,whichinturnsitsinatubefilledwithhydraulicfluid.Theinnertubeisknownasthepressuretube,andtheoutertubeisknownasthereservetube.Thereservetubestoresexcesshydraulicfluid.Whenthecarwheelencountersabumpintheroadandcausesthespringytocoilanduncoil,theenergyofthespringistransferredtotheshockabsorberthroughtheuppermount,downthroughthepistonrodandintothepiston-Orificesperforatethepistonandallowfluidtoleakthroughasthepistonmovesupanddowninthepressuretube.Becausetheorificesarerelativelytiny,onlyasmallamountoffluid,undergreatpressure,passesthrough.Thisslowsdownthepiston,whichinturnslowsdownthespring.Shockabsorberswor
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
- 2-Aza-ε-adenosine-2-Aza-1-N6-ethenoadenosine-生命科学试剂-MCE
- 2024年吉林省长春市九年级中考一模数学试题
- 建筑取样员岗位职责
- 【信息技术】信息安全与社会责任 检测练习-2023-2024学年人教中图版(2019)高中信息技术必修2
- 中考语文复习情感交融的小说写作
- 拆迁协调方案
- 中考语文复习名著中人物的性格鉴定
- 语文备考锦囊
- 关于《教育从爱开始》摘抄及感悟《教育从爱开始》读书笔记【三篇】
- 中考复习语文的作用和意义
- 贵州铜仁革命军事陈列馆公开招聘劳动合同制派遣人员2人模拟预测(共500题)笔试参考题库附答案详解
- 洗车机现场处置方案模板
- 大学生志愿服务西部计划考试复习题库(笔试、面试题)
- 中医内科学咳嗽
- 5G基站行业现状分析及发展前景报告
- 2023新疆公务员考试笔试真题
- 幼儿园语言活动课件《章鱼先生卖雨伞》
- 风险危险源辨识统计表
- 天然气燃气管网突发事故应急预案
- 2023年道路运输企业主要负责人考试题库及答案
- 血气分析六步法PPT
评论
0/150
提交评论