制动系统--文献翻译

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1、BrakesystemAutomobilebrakeisthemostimportantsystemincars.Brakeareactuallyenergyconversion,whichconvertthekineticenergyofthevehicleintothermalenergy.Whensteppingonthebrakes,thedrivecommandsastoppingforcetentimesaspowerfulastheforcethatputsthecarsinmotin.Thebrakeingsystemcanex

2、ertthousandsofpoundsofpressureoneachofthefourbrakes.Eachvehiclemusthavetwoindenpentbrakesystemsforsafety.Themainbrakesystemwhichislocateunderthehoodandisdirectlyconnecttothebrakepedalishydraulicallyoperatedandiscalledtheservicebrakesystem.Thesecondaryorparkingbrakesystemisme

3、chanicallyoperated.Toincreasesafety,mostmoderncarbrakesystemarebrokenintotwocircuits,withtwowheelsoneachcircuit.Thereisafluid-filledcylinder,calledthemastercylinder.Itsuppliespressuretohothcircuitsofthecar,andifafluidleakoccursinonecircuit,onlytwoofthewheelswilllosetheirbrak

4、esandthecarwillbestopped.Whythatpushigdownonthebrakepedalcanslowacartostop?Howdosethecartransmitstheforcefromthedriver’legtoitswheel?Itistheworkthatbrakesdid.21LayoutofTypicalBrakesystemWhendepressingthebrekepedal,thecartransmitstheforcethedrive’sfoottoitsbrakesthroughafluid

5、.Sincetheactualbrakesrequireamuchgreaterforcethanthedrivecouldapplywithhisleg,thecarmustalsomultipytheforceofthedriver’sfoot.Itdosethisintwoways:mechanicaladvantageandhydraulicforcemultiplication.LevergeThepedalisdesignedinsuchawaythatitcanmultiplytheforcefromthedriver’slegs

6、everaltimesbeforeanyforceiseventransmittedtothebrakefluid.Inthefigureabove,aforceFisbeingappliedtotheleftendofthelever.Theleftendoftheleveristwiceaslong2X)astherightend(x).Therefore,ontherightendoftheleveraforceof2Fisavailable,butitactsthroughhalfofthedistans(Y)thattheleften

7、dmoves(2Y).Changingtherelativelengthsoftheleftandrightendsoftheleverchangesthemulitipliers.HydraulicBrakeSystemsThehydraulicsystemisthatforceappliedatonepointisthansmittedtoanotherpointusinganincompressiblefluid,almostalwaaysanoilofsomesort.Mostbrakesystemsalsomuitiplythefor

8、ceintheprocess.Thegreatthingabouthydraulicsystemsisthatthepipeconnectingthe