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ID:52331530
大小:2.83 MB
页数:17页
时间:2020-03-26
《汽车制动系统-英文文献及翻译.doc》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、BrakesystemsWeallknowthatpushingdownonthebrakepedalslowsacartoastop.Buthowdoesthishappen?Howdoesyourcartransmittheforcefromyourlegtoitswheels?Howdoesitmultiplytheforcesothatitisenoughtostopsomethingasbigasacar?BrakeImageGalleryLayoutoftypicalbrakesystem. Seemorebrakeimages
2、.Whenyoudepressyourbrakepedal,yourcartransmitstheforcefromyourfoottoitsbrakesthroughafluid.Sincetheactualbrakesrequireamuchgreaterforcethanyoucouldapplywithyourleg,yourcarmustalsomultiplytheforceofyourfoot.Itdoesthisintwoways:·Mechanicaladvantage(leverage)·Hydraulicforcemu
3、ltiplicationThebrakestransmittheforcetothetiresusingfriction,andthetirestransmitthatforcetotheroadusingfrictionalso.Beforewebeginourdiscussiononthecomponentsofthebrakesystem,we'llcoverthesethreeprinciples:·Leverage·Hydraulics·FrictionLeverageandHydraulicsInthefigurebelow,a
4、forceFisbeingappliedtotheleftendofthelever.Theleftendoftheleveristwiceaslong(2X)astherightend(X).Therefore,ontherightendoftheleveraforceof2Fisavailable,butitactsthroughhalfofthedistance(Y)thattheleftendmoves(2Y).Changingtherelativelengthsoftheleftandrightendsoftheleverchan
5、gesthemultipliers.Thepedalisdesignedinsuchawaythatitcanmultiplytheforcefromyourlegseveraltimesbeforeanyforceiseventransmittedtothebrakefluid.Thebasicideabehindanyhydraulicsystemisverysimple:Forceappliedatonepointistransmittedtoanotherpointusinganincompressiblefluid,almosta
6、lwaysanoilofsomesort.Mostbrakesystemsalsomultiplytheforceintheprocess.Hereyoucanseethesimplestpossiblehydraulicsystem:YourbrowserdoesnotsupportJavaScriptoritisdisabled.SimplehydraulicsystemInthefigureabove,twopistons(showninred)arefitintotwoglasscylindersfilledwithoil(show
7、ninlightblue)andconnectedtooneanotherwithanoil-filledpipe.Ifyouapplyadownwardforcetoonepiston(theleftone,inthisdrawing),thentheforceistransmittedtothesecondpistonthroughtheoilinthepipe.Sinceoilisincompressible,theefficiencyisverygood--almostalloftheappliedforceappearsatthe
8、secondpiston.Thegreatthingabouthydraulicsystemsisthatthepipeconnectingthetwocylinderscanb
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