盤(pán)式制動(dòng)器中英文對(duì)照外文翻譯文獻(xiàn)

PAGEPAGE20中英文對(duì)照外文翻譯文獻(xiàn)(文檔含英文原文和中文翻譯)外文：AnExperimentalAnalysisofBrakeEfficiencyUsingfourFluidsinaDiscBrakeSystemABSTRACTThepaperstudiesdiscbrakefailureinMini-busesusinganexperimentalanalysistotestthemaximumbrakingforcewhendifferentbrakefluidssuchasclean,lessdirty,dirtyandsoapywatersolutionwereusedinthebrakingsystem.Theexperimentalresultsclearlyshowedthatthesoapsolutionappearstobethebestfluidasfaraslowviscosityandstabilityofviscositywithincreaseintemperatureareconcerned.However,thesoapsolutionisnotcompatiblewithotherfluidwhichmakesitdifficulttobesubstituteasacleanbrakefluid.TheresultoftheThepraUniversalBrakeTestingEquipmentusedforthebrakingefficiencytestindicatedthatapedalbrakeof117kNproduceabrakeforceof0.96kNforcleanbrakefluid,0.91kNforthelessdirty,0.85kNfordirtyand1.44kNforsoapsolution.Thevalueof1.44kNwhichwasachievedwhenthesoapsolutionwasusedindicatedapositivebrakingforceandtheindicatingthatsoapsolutioncouldbeusedtoproduceahighpedalforcewithinaveryshorttime(about10-30min)andcanthereforebeusedonlyincaseofemergency.Thebrakeefficiencytestindicatedthatunderhotconditionsthebrakingefficiencyisreducedandthepresenceofairinthesystemrendersthebrakingineffectivebecausehigherpedalforcewasneededtobeabletoproduceasignificantbrakingforcewhichisnotedforcausingbrakefailure.Keywords:Brakefade,brakefailure,discbrake,efficiency,pedalforceINTRODUCTIONWhenavehicleisaccelerated,energysuppliedbytheenginecausesthevehicle’sspeedtoincrease.Partofthisenergyisinstantlyusedupinovercomingfrictionalandtractiveresistancebutalargeamountofitremainsstoredinthevehicle.AccordingtoHeinz(1999)thisenergyofmotioniscalledthekineticenergyandtheexistenceofkineticenergyisobservedwhenavehicleismovingandneutralgearisselected.Thevehicledoesnotimmediatelycometorest;insteadittravelsforaconsiderabledistancebeforeitbecomesstationary.Inthiscasethestoredenergyisusedtodrivethevehicleagainsttheresistancesthatopposethevehicle’smotion.Relyingontheseresistancestoslowdownavehiclecouldcausemanyproblems,soanadditionalresistancecalledabrakeisneededtoconvertthekineticenergytoheatenergyatafasterrateinordertoreducethespeedofthevehicleMcpheeandJohnson(2007).Thisreducesthespeedofthevehicleatafasterrateandbringsthevehicletorestwithintheshortestpossibletimewhenthebrakesareapplied.FromthepointofviewofJohnsonetal.(2003)mostautomotivesystemsinusetodayutilizefrontdiscbrakes,butfour-wheeldiscsystemsarealsocommonIndiscbrakes,therotorrotateswiththewheelandthepadsmoveouttorubtherotorwhenthebrakesareapplied.Mostdiscbrakesusefloatingcalipers.Thecaliperslidesinandoutasthebrakesareappliedandreleased.Thepistonmovestheinsidepadoutandpushestheoutsidepadintotherotorbyslidingthecaliperbacktowardtherotor.TheuseofdiscbrakestoreducespeedorbringthevehicletorestwheninmotioncannotbeoveremphasizedifthesafetyoftheoccupantistobeguaranteedHeinz(1999).Tobringavehicletoastop,thediscbrakeshavetoabsorballtheenergygiventothevehiclebytheengineandthatduetothemomentumofthevehicle.Thisenergymustthenbedissipated.Inmostvehiclediscbrakes,theenergyisabsorbedbyfriction,convertedintoheatandtheheatdissipatedtothesurroundingair(Thoms,1988).Astheenergyisabsorbed,thevehicleissloweddown;inotherwords,itsmotionisretarded.Thebrakesmustalsopullupthevehiclesmoothlyandinastraightlinetobringthevehicletoastopposition.Itisthereforeveryimportantthatthediscbrakesofvehiclesoperatewiththehighestefficiency.Thiscouldreducetherateofaccidentsduetobrakefailuresothatlifeandpropertycouldbepreservedandalsotoensurethatoccupantsofthesecommercialvehiclesgoabouttheirnormalliveswithoutanyfearofbeinginvolvedinanaccident.AvailablecrashdatainGhanasuggeststhatabout1,900personsarekilledannuallyinroadtrafficcrashes(Afukaaretal.,2008)andthatmorethan40%oftheroadtrafficfatalitiesareoccupantsofcars,busesandtrucks.Mostoftenthannot,someoftheroadaccidentsinvolvingcommercialvehicles,suchasthemini-buseshavebeenattributedtothefailureofthediscbrakes.Thereasonfortestingtheviscosityofthesebrakefluids,especiallythatofthesoapsolutionwasasaresultofthepracticeofmostGhanaiandriverssometimesusingthesoapysolutionasasubstitutetotheoriginalbrakefluidinthebrakingsystemandalsousingdirtybrakefluidwhichhasbeenusedforbleedingpurposes.Themainobjectiveofthisstudywhichispartofalargerworkseekstoinvestigateandestablishthereasonsforthediscbrakefailureduetobrakefluidalsochecktheefficiencyofthefourdifferenttypesoffluidsusedinthetransmissionofbrakingforces.Thestudylookedatthemaximumbrakingforcewhenusingclean,lessdirty,dirtyandsoapywatersolutioninthebrakingsystem.ItalsolookedatthebrakingforcewhenthebrakingsystemiswithorwithoutservounitandoperatingundercoldorhotconditionwithairorwithoutairinthebrakingsystemDISCBRAKESThediscbrakeconsistsofanexposeddiscwhichisattachedtothehubflange;thetwofrictionpadsarepressedontothisdisctogiveabrakingaction.Figure1a,showsthediskbrakesystemofacarandpadthatisseparatedfromwheelassemblytobettershowsthediskandthepadinslidingcontact.Asitcanbeseen,typicaldiskbrakesystemandcaliperassemblyofasoliddiskbrakerotoriscompletelynoticeable.Figure1bshowsschematicformofthediskandthepadinslidingcontactassembly.(a)(b)Fig.1:DiscbrakeThepadsaremovedbyhydraulicpistonsworkingincylindersformedinacaliperthatissecuredtoafixedpartoftheaxle.Whenthehydraulicpressureisappliedtothetwocylindersheldinthefixedcaliper,thepistonsmove;thisactionforcesthefrictionpadsintocontactwiththerotatingcastirondisc.Thesandwichingactionofthepadsonthediscgivesaretardingactionandheatgeneratedfromtheenergyofmotionisconductedtothedisc.Greaterpartofthediscisexposedtotheair;thereforeheatiseasilyradiated,withtheresultthatthebrakecanbeusedcontinuouslyforlongperiodsbeforeseriousfadeoccurs.Sincethefrictionpadsmoveatarightangletothedisc,anydropinthefrictionvaluedoesnotaffecttheforceappliedtothepad.Asaresultthistypeofbrakeisnotlesssensitivetoheat(Mudd,1972).Thediscbrakewasdevelopedtominimizethefadeproblems.Whenfadingoccurs,thedriverhastoapplyamuchlargereffortandinextremecasesitbecomesimpossibletobringthevehicletorest.Noassistanceisobtainedfromtherotatingdisctoaidthedriverintheapplicationofadiscbraketoachieveagivenretardation.Adiscbrakerequiresagreaterpedalpressureandtoachievethispressurerequiredthehydraulicbrakingsystemusingagoodqualitybrakefluidinitsoperation.Thefluidusedinthehydraulicbrakingsystemsisavegetableoilwithcertainadditives.AccordingtoNunneyetal.(1998)agoodbrakefluidshouldhavethefollowingrequirements,lowviscosity,highboilingpoint,compatibilitywithrubbercomponents,lubricatingproperties,resistancetochemicalageingandcompatibilitywithotherfluids.However,mostGhanaiandriverssometimesusedotherfluidsuchasdirtybrakefluid,lessdirtyfluidandevensoapywatersometimesasasubstitutedtotheoriginalbrakefluid.Thisstudyamongotherthingswillalsoinvestigatewhichofthesebrakefluid,clean,dirty,lessdirtyandsoapywaterwillhavethebestviscosity,highboilingpointandlessbrakingforce.MATERIALSANDMETHODSThedesignusedforthisstudywasexperimentwhichemployedtheusedofviscometerandThepraUniversalAutomotiveBrakeTestingmachinetochecktheefficiencyofthefourfluidsinthetransmissionofbrakingforces.Laboratoryanalysis:TheviscositytestsonthefourdifferentliquidswerecarriedoutattheKwameNkrumahUniversityofScienceandTechnology(KNUST)Thermodynamicslaboratory.Theliquidswerecleanbrakefluid,lessdirtybrakefluid,dirtybrakefluidandsoapsolution.Itwasnecessarytofindouthowtheviscosityofdifferentqualitiesofbrakefluidaffectedbrakingefficiencyandtofindoutwhethertherewasanycorrelationbetweentheseandtheoccurrenceofbrakefailure.Viscositytestonthevariousfluidsused:TheviscositytestwascarriedoutonaRedwoodViscometerinFig.2onthefourdifferentkindsoffluidstodeterminetheirviscosities.Theapparatusconsistsofaverticalcylindercontainingthefluidundertestwhichwasallowedtoflowthroughacalibratedorificesituatedatthecentreofthecylinderbase.Theorificeisclosedbyaballvalvewhenitisnotbeingused.Fig.2:RedwoodviscometerusedtodeterminetheviscosityofthefluidsTheoilcylinderissurroundedbyawaterjacketwhichmaintainsthelubricantundertestatarequiredtemperaturebymeansofaBunsenburnerflameappliedtotheheatingtube.Thethermometerforthewaterinthejacketismountedinapaddle-typestirrerwhichcanberotatedbyhand,usingthehandle(Zammit,1987).Procedurefortestingvariousviscositiesofthefluids:Totesttheviscosityofafluid,thewaterjacketwasfilledwithwaterwiththeorificeballvalveinposition.Fluidwaspouredintothecylindertothelevelofthepointer.A50mLmeasuringflaskwasplacedcentrallyundertheorifice.Thewaterwasstirredgentlyuntilthewaterandfluidthermometerswerethesame(roomtemperature,30oC).Thetemperaturewasrecorded.Theballvalvewasthenraisedandastopwatchusedtorecordthetime(inseconds)fora50mLoffluidtoflowintothemeasuringflask.Thetestwasrepeatedwiththefluidtemperaturesincreasingby10oCeachtimeupto90oC.AllthedataforthefourdifferentfluidswererecordedasshowninTable1Theprauniversalstandautomotivebraketestingequipment:TheThepraUniversalStandAutomotivebraketestingequipmentisstructuredinsuchawaythatthedrivenpart,suchasbrakedisc,waspluggedontothemotorshaft.Thebrakeanchorplateandthecaliperarefastenedtoaflangeviaalinkageofbarwhichisconnectedtotheflange.Thebrakeforceismeasuredanddisplayedonadigitalindicator.Theindividualunitsarepluggedintothetwospan-frameswhicharefastenedtobothsides.Allthebrakecomponentsusedinthetestingequipmentareoriginalvehiclecomponents.Thepedalforceismeasuredattheactuatinglinkageofthebrakemastercylinderanddisplayedonadigitalindicator(Technolab,2009)RESULTSANDDISCUSSIONExperimentalresultsofviscositytest:Table1presenttheresultsofviscositytestinanexperimentforthefourfluids,usingtheRedwoodViscometer.FromthetestresultsobtainedusingRedwoodviscometer,Viscosity-Temperaturegraphsforthefluidswereplotted.Figure3showstheplotofviscosityagainsttemperatureofthefourfluids.Table1:ViscositytestValuesofthevariousviscositieswerecalculatedusingtheformula:V=hfρgD232hfvValuesofthevariousviscositieswerecalculatedusingtheformula:V=hfρgD232hfvwhere,V:TheViscosityhf:Thecapillaryheightρ:Thedensityofthefluidg:AccelerationduetogravityD:Thediameteroftheorificev:Thevelocity(Birdetal.,1960)FromFig.3thedirtyfluidhasthehighestviscosityfollowedbythelessdirtyfluid,cleanfluidandsoapsolutioninthatorder.FromtheresultsshowninFig.2andtheviscositytestshowninTable1,thesoapsolutionappeartobethebestfluidasfaraslowviscosityandstabilityofviscositywithincreaseintemperatureareconcerned.However,itislesscompatiblewithotherfluids,difficulttomixeasilywithotherbrakefluidsandhasalowboilingpointwhichwillnotmakeitsuitabletobesubstituteascleanbrakefluid(Nunneyetal.,1998).Thecleanbrakefluidisnextasfarasviscosityandstabilityofviscositywithincreaseintemperatureareconcerned.Ontheotherhand,itsatisfiesalltheotherrequirementsofagoodfluidforthebrakingsystemgiveninTable1.AccordingtoMudd(1972)andNunneyetal.(1998),agoodbrakefluidshouldhavepropertiessuchashighboilingpoint,compatibilitywithrubbercomponents,goodlubricationproperties,resistancetochemicalageing(longshelflife)andcompatibilitywithotherfluids.Thelessdirtyfluidisveryunstableasfarasviscositychangewithtemperatureincreaseisconcerned.Itisthereforenotveryreliableinabrakingsystemsinceitsbehaviorchangesasthebrakingsystemheatsup.Theviscosityofthedirtyfluidisstablewithincreaseintemperature,however,itisveryviscous(235-178kgs/m3inthetemperaturerange30to90oC).Itwillthereforenotbegoodandeffectiveinbrakeforcetransmission.Fromtheseresultsandliterature,itisobviousthatthecleanbrakefluidismoresuitableforthetransmissionofbrakingforceasit’spossessallthegoodbrakefluidqualities.Experimentalresultsofthediscbrakesystem:ThesesectionspresenttheresultsanddiscussionoftheexperimentsusingthefourfluidsinaDiscbrakesystemunderdifferentconditions.TestresultsforhotandcoldconditionsoftheDiscbrakesystemusingaservosystemandwithoutusingaservosystemwereconsidered.Discbrakeincoldconditionwithandwithoutservounit:TheresultinTable2clearlyshowsthepedalforceandthebrakeforceforclean,lessdirty,dirtyandsoapsolutionwhenusingdiscbrakeincoldconditionwithservounitwiththeThepraUniversalBrakeTestingEquipment.Apedalbrakeof117kNproduceabrakeforceof0.96kNforacleanbrakefluid,Table2:ResultsofdiscbrakeincoldconditionwithservoTable3:Resultsofdiscbrakeinhotconditionwithservo0.91kNforthelessdirty,0.85kNfordirtyand1.44kNforsoapsolution.Comparatively,amaximumbrakeforceisachievedwhenthefluidisclean.Whenthereisthepresenceofdirt,thebrakeforcedecreasesandthereforemorepedalforceisneededtotakeupthewithoutservolosscreatedbythedirt.Hencethegreaterthedirt,thegreaterthepedalforcerequired.Thevalueof1.44kNwhichwasachievedwhenthesoapsolutionwasusedindicatedapositivebrakingforcecomparedwithallthethreefluidsatthesamepedalforce.SubsequentpedalforcesappliedasshowninTable2gaveareductioninthebrakeforcewhensoapsolutionwasused.Theimplicationwasthatsoapsolutioncouldbeusedtoproduceahighpedalforcewithinaveryshorttime(about10-30min)andcanthereforebeusedincaseofemergency.FromTable2,itcanbeobservedthatforthesamepedalforceof117KNthesoapsolutiontransmittedthehighestamountofbrakeforcefollowedbythecleanfluid,lessdirtyfluidanddirtyfluidinthatorder.Thisimpliesthatincoldconditionusingservo,thesoapsolutionperformsbestfollowedbytheclean,lessdirtyanddirtyrespectively.Discbrakeinhotconditionwithservounit:Whentheexperimentwascarriedoutusingadiscbrakeunderthehotconditionswiththeintroductionofaservo,apedalforceof120kNgaveabrakeforceof0.95kNforcleanfluid,0.90kNforlessdirty,0.85kNforadirtyfluidand0.19KNforsoapsolution.Theresultcouldbeexplainthat,thecleanbrakefluidgavethehighestbrakeforcefollowbylessdirty,dirtyandsoapsolution.Itwasobservedthatthesoapsolutionperformpoorlyatthistimerecordingabrakeforceof0.19KNasshowninTable3.Discbrakeinhotconditionwithoutservo:Figure4showsaplotofdiscbrakeinhotconditionwithoutservounit.Itcanbeobservedthat,underhotconditionsforthediscbrakewithoutservo,thetrendisgenerallythesame.Thesoapsolutionperformedverybadlycomparewiththeotherfluids,unlikeitsperformanceundercoldconditions.Thismaybeduetoevaporationofthefluidmakingthefluidcompressible;asifairwasinthebrakingsystem.Generally,thecleanfluidperformedbestintermsoftransmissionofbrakeforcefollowedbythelessdirty,dirtyandsoapsolutioninthatorder.Discbrakewithairinsystemundercoldcondition:BrakingforceforthisexperimentwasgenerallylowascomparedwiththecasewhenairwasnottrappedinthesystemasshowninTable4.Whentheexperimentwasconductedwithapedalforceof165kN,brakingforceofTable4:ResultsofdiscbrakewithairinsystemundercoldconditionwithservoFig.5:Resultsofdiscbrakewithairinsystemunderhotconditionwithservo0.32kNsoapsolutionwasobtained,for0.37KNfordirty,0.28KNforlessdirtyand0.30kNforcleanfluid.ThisisinlinewithliteraturebecauseaccordingtoMudd(1972)thepresenceofairinthebrakingsystemmakesthesystemineffectivesincemuchofthedriverseffortwillbeusedtocompresstheairleavingverylittleforthebrakeapplication.Again,thesoapsolutiondidnotgivetheleastbrakingforcebecausewhenthesystemiscold,soapsolutioniseffectiveanditsdensityishighersincethereisnooccurrenceofevaporationofthesolution.Discbrakewithairinsystemunderhotcondition:TheFig.5showstheplotofagraphindicatingdiscbrakewithairinthesystemunderhotconditionclearlyshowsthat,whenapedalforceof152kNwasapplied,abrakeforceof1.11kNwasobtainedforclean,0.37kNforlessdirty,0.28kNfordirtyand0.26kNforsoapsolution.Itwasobservedthatthemaximumbrakeforcewasattainedwhenthefluidwascleanandontheintroductionofdirtyfluid,thebrakeforcereduceddrastically,thoughthepedalforcewasveryhighat152kNinthehotcondition.Soapsolutionprovidestheleastbrakeforcebecausetheaircontentinthesystemincreasesduetoevaporationandhencethepedalforcecompressesairratherthantransmittingpower.Asthesystemheatsup,theairinthesystemexpandstherebyreducingthebrakingefficiencywhichresultsinbrakefailure.CONCLUSIONThestudywasconductedusinganexperimentperformedonaThepraBrakeTestingEquipmenttochecktheefficiencyofthefourfluidsinthetransmissionofbrakingforces.Accordingtotheviscometertestshownthatthesoapsolutionappearstobethebestfluidasfaraslowviscosityandstabilityofviscositywithincreaseintemperatureisconcerned.However,itislesscompatiblewithotherfluids,difficulttomixeasilywithotherbrakefluidsandhasalowboilingpointwhichwillnotmakeitsuitabletobesubstitutedasacleanbrakefluid.Again,whenairistrappedinthebrakingsystem,whichresultsinthebrakefluidbeingcompressible,higherpedalforcewasneededtobeabletoproduceasignificantbrakingforce.Also,whenbrakesareoperatedunderhotconditionsitsefficiencyisreduced,afaultknownasbrakefadeoccursasaresultoftheheatingupofthebrakeswhichcreateslessfrictionalresistancebetweenrotatingdiscandthefrictionalpads.Finally,Soapsolutionwhenusedatcoldconditionproduceshighbrakingforcebutbecomeslesseffectiveafterprolonguseduetothepresenceofheatwhichevaporatesthesoapsolution.REFERENCESAfukaar,F.,K.Agyemang,W.AckaahandI.Mosi,2008.RoadtrafficcrashesinGhana,statistics2007.ConsultancyServiceReportforNationalRoadSafetyCommissionofGhana.Bird,R.,S.WrightandE.N.Light,1960.TransportPhenomena,GibrinePublishingCompany,Heinz,H.,1999.VehicleandEngineTechnology.2ndEdn.,Butterworth-HeinemannPublications,Nurumberg,pp:235-291Johnson,D.,B.SperandeiandR.Gilbert,2003.Analysisoftheflowthroughaventedautomotivebrakerotor.J.FluidsEng.,125:979-986.Mcphee,A.D.andD.A.Johnson,2007.Experimentalheattransferandflowanalysisofaventedbrakerotor.Int.J.ThermalSci.,47(4):458-467.譯文：一個(gè)使用四個(gè)液體系統(tǒng)分析盤(pán)式制動(dòng)器的制動(dòng)效率的實(shí)驗(yàn)摘要當(dāng)車(chē)輛加速時(shí)能量由發(fā)動(dòng)機(jī)提供使汽車(chē)的速度增加。這部分能量會(huì)瞬間消耗在克服摩擦和牽引阻力,但大量的仍然是存儲(chǔ)在車(chē)輛當(dāng)中。根據(jù)亨氏(1999)這個(gè)運(yùn)動(dòng)的能量叫做動(dòng)能并且當(dāng)車(chē)輛移動(dòng)和中型齒輪被選中時(shí)才會(huì)被觀察到。車(chē)輛沒(méi)有立即進(jìn)行制動(dòng)，相反，它為以后行駛長(zhǎng)距離而變得平穩(wěn)。在這種情況所儲(chǔ)存的能量用于驅(qū)動(dòng)所述車(chē)輛針對(duì)相對(duì)車(chē)輛的運(yùn)動(dòng)的阻力。依靠這些阻力來(lái)減緩車(chē)輛可能會(huì)導(dǎo)致許多問(wèn)題，因此需要一個(gè)額外的以更快的速度將懂你呢轉(zhuǎn)換為熱能的阻力來(lái)進(jìn)行制動(dòng)，以減少車(chē)輛麥克菲和約翰遜（2007）的速度。這以更快的速度降低了車(chē)輛的行使速度，使車(chē)輛在最短的反應(yīng)時(shí)間內(nèi)進(jìn)行制動(dòng)。從約翰遜等人的觀點(diǎn)來(lái)看。大多數(shù)汽車(chē)系統(tǒng)現(xiàn)在使用前剎車(chē)盤(pán)，但四輪盤(pán)式制動(dòng)系統(tǒng)也是常見(jiàn)的盤(pán)式制動(dòng)器，與車(chē)輛一同旋轉(zhuǎn)的轉(zhuǎn)子和在摩擦墊進(jìn)行移動(dòng)后產(chǎn)生摩擦力以進(jìn)行制動(dòng)。大多數(shù)的盤(pán)式制動(dòng)器是使用浮動(dòng)卡鉗式。當(dāng)制動(dòng)器被應(yīng)用并釋放時(shí)，活塞將移動(dòng)的內(nèi)墊推出并通過(guò)滑動(dòng)卡鉗朝轉(zhuǎn)子方向推壓內(nèi)墊。盤(pán)式制動(dòng)器的是為了降低車(chē)輛的行駛速度或者進(jìn)行制動(dòng)。但為了保證乘客的安全，在車(chē)輛行駛過(guò)程中不能過(guò)分的使用。由于車(chē)輛的動(dòng)力，為了使車(chē)輛制動(dòng)盤(pán)式制動(dòng)器必須吸收發(fā)動(dòng)機(jī)的所有能量，這種能量必須被散發(fā)掉。在大多數(shù)車(chē)輛的盤(pán)式制動(dòng)器中，能量通過(guò)摩擦被吸收，轉(zhuǎn)化成熱能并耗散到周?chē)目諝庵?。隨著能量被吸收，車(chē)輛速度減緩，換句話(huà)說(shuō)，他的運(yùn)動(dòng)是滯后的。制動(dòng)器還必須保證車(chē)輛順利的停止在一條直線(xiàn)上。車(chē)輛的盤(pán)式制動(dòng)器以最高的效率運(yùn)行可能會(huì)減少因剎車(chē)失靈而導(dǎo)致的事故率，從而使生命財(cái)產(chǎn)得以保護(hù)，同時(shí)也保證了這些車(chē)內(nèi)人員的正常的工作和生活而無(wú)須擔(dān)心被卷入事故當(dāng)中。在加納提供事故數(shù)據(jù)中表明每年約1900的人在道路交通事故中死亡并且以上的交通事故中有40%發(fā)生在轎車(chē)、公共汽車(chē)和乘用卡車(chē)上。最為常見(jiàn)的是，一些一些涉及交通事故的車(chē)輛如小型汽車(chē)已經(jīng)歸因于剎車(chē)盤(pán)剎車(chē)失靈。由于大多數(shù)的加納司機(jī)將肥皂溶液等骯臟的制動(dòng)液用來(lái)替代原制動(dòng)系統(tǒng)制動(dòng)液以達(dá)到討厭的目的，所以我們對(duì)這些制動(dòng)液的粘度進(jìn)行測(cè)試，特別是皂液。這項(xiàng)研究是一個(gè)更大的工作的一部分，旨在探討和尋找盤(pán)式制動(dòng)器制動(dòng)故障的原因，還要檢查制動(dòng)力的傳遞中使用的四種不同類(lèi)型的液體的效率。這項(xiàng)實(shí)驗(yàn)研究在使用清潔、不清潔、骯臟和肥皂水四種不同的溶液在制動(dòng)系統(tǒng)中的能產(chǎn)生的最大制動(dòng)力。制動(dòng)系統(tǒng)在冷空氣或熱空氣或沒(méi)有空氣的情況下，產(chǎn)生的制動(dòng)力也是不一樣的。盤(pán)式制動(dòng)器盤(pán)式制動(dòng)器由一個(gè)被連接到輪轂凸緣的外露盤(pán)組成；兩個(gè)摩擦片被壓在這個(gè)圓盤(pán)上，以使制動(dòng)作用。圖1a顯示從車(chē)輪組件分離的汽車(chē)制動(dòng)系統(tǒng)，更好的顯示出摩擦片和外露盤(pán)是分開(kāi)安裝的在滑動(dòng)接觸中。可以看出，典型的盤(pán)式制動(dòng)器系統(tǒng)和制動(dòng)盤(pán)的制動(dòng)盤(pán)總成是完全不引人注目的。圖1b顯示磁盤(pán)示意圖的形式和墊在滑動(dòng)接觸組件。(b)圖一：盤(pán)式制動(dòng)器該墊是通過(guò)在一個(gè)圓筒中形成的咦個(gè)固定在輪軸上的固定卡鉗里的液壓活塞桿工作而移動(dòng)的。當(dāng)液壓壓在固定的卡鉗上時(shí)，活塞移動(dòng)時(shí)，該動(dòng)作將摩擦盤(pán)與旋轉(zhuǎn)的鑄鐵盤(pán)接觸。摩擦盤(pán)上的墊進(jìn)行夾持的動(dòng)作產(chǎn)生了一個(gè)緩滯的作用并且將運(yùn)動(dòng)的能量轉(zhuǎn)換的熱量傳遞到圓盤(pán)上。大圓盤(pán)的一部分暴露在空氣中,因此很容易散熱,所以制動(dòng)系統(tǒng)可以在發(fā)生很?chē)?yán)重的失靈之前被連續(xù)使用。由于摩擦片以一個(gè)正確的角度移動(dòng)到圓盤(pán)，所以任何下降的摩擦值不影響施加到墊的力。所以這種類(lèi)型的制動(dòng)器對(duì)于熱并不是那么的不敏感。盤(pán)式制動(dòng)器的開(kāi)發(fā)研究為降低制動(dòng)失靈問(wèn)題。制動(dòng)失靈發(fā)生時(shí),司機(jī)必須花費(fèi)更大的力并且在極端情況下,無(wú)法將車(chē)輛停止。在盤(pán)式制動(dòng)器作用時(shí)，沒(méi)有任何設(shè)備去幫助司機(jī)在旋轉(zhuǎn)的制動(dòng)盤(pán)上去實(shí)現(xiàn)多余的制動(dòng)。盤(pán)式制動(dòng)器需要一個(gè)更大的踏板壓力，液壓制動(dòng)系統(tǒng)使用一個(gè)良好的質(zhì)量制動(dòng)液在其操作以達(dá)到這個(gè)壓力要求。液壓制動(dòng)系統(tǒng)中所用的流體是一種植物油，具有一定的添加劑。據(jù)倫尼說(shuō)，良好的制動(dòng)液應(yīng)具有以下要求，低粘度、高沸點(diǎn)、與橡膠部件的相容性、潤(rùn)滑性能、耐化學(xué)老化性及與其它流體的相容性。無(wú)論何時(shí)，越多越好。加納司機(jī)有時(shí)將一些如低劣的制動(dòng)液、臟的流體甚至肥皂水作為制動(dòng)液以代替原來(lái)的制動(dòng)液.。這項(xiàng)研究中，也將探討這些清潔，骯臟，不潔和皂水的制動(dòng)液將有更好的粘度，更高的沸點(diǎn)和更少的制動(dòng)力。材料與方法本研究是采用用粘度計(jì)和thepra通用汽車(chē)制動(dòng)試驗(yàn)臺(tái)檢測(cè)四種液體在制動(dòng)力的傳輸效率的實(shí)驗(yàn)設(shè)計(jì)。圖二：烏氏粘度計(jì)測(cè)定液體的粘度實(shí)驗(yàn)室分析：在夸梅恩克魯瑪科技大學(xué)進(jìn)行（KNUST）熱力學(xué)實(shí)驗(yàn)室進(jìn)行四種不同的液體的粘度測(cè)試。分別是：液體清潔制動(dòng)液、稍微骯臟的制動(dòng)液、骯臟的制動(dòng)液和作為解決方案的皂液。有必要找出不同質(zhì)量的制動(dòng)液的粘度對(duì)制動(dòng)效率的影響，并找出這些與制動(dòng)故障的發(fā)生之間是否存在相關(guān)性。在各種流體粘度測(cè)試：在圖2的紅木粘度計(jì)對(duì)四種不同種類(lèi)的流體進(jìn)行粘度測(cè)試。該裝置包括一個(gè)裝著測(cè)試所用流體的垂直圓柱體，圓柱體在一個(gè)允許流體通過(guò)的一個(gè)位于中心的校準(zhǔn)孔氣缸底座的下面。當(dāng)不使用時(shí)，該孔由球閥關(guān)閉。這個(gè)液壓缸被一個(gè)在試驗(yàn)中用來(lái)保持潤(rùn)滑的水套緊緊密封著，用一個(gè)本生燈的火焰進(jìn)行加熱，用來(lái)測(cè)試一個(gè)溫度。水套溫度計(jì)被安裝在一個(gè)有旋轉(zhuǎn)葉片的攪拌器里進(jìn)行使用。用于測(cè)試各種粘度的流體的方法：為了測(cè)試流體的粘度，在用孔球閥的位置上填充了水夾套。流體注入到氣缸的水平的位置。一個(gè)50毫升的測(cè)量瓶被放置在中央的孔下。水被輕輕地?cái)嚢?，直到水和液體溫度計(jì)顯示的溫度是一樣的（室溫，30oC）。記錄溫度，然后球閥浮起，用一個(gè)秒表來(lái)測(cè)量液體流入這個(gè)50毫升的測(cè)量瓶所用的時(shí)間。實(shí)驗(yàn)重復(fù)多次，每次試驗(yàn)溫度最低10oC最高90o，記錄四種不同的流體的所有數(shù)據(jù)，如表1所示。表1：粘度試驗(yàn)汽車(chē)制動(dòng)檢測(cè)設(shè)備：普遍的汽車(chē)制動(dòng)檢測(cè)設(shè)備是這樣一種結(jié)構(gòu)，驅(qū)動(dòng)部分是制動(dòng)盤(pán)插入到電機(jī)軸。制動(dòng)錨板和制動(dòng)鉗通過(guò)一個(gè)連桿連接緊固到一個(gè)法蘭上。測(cè)量制動(dòng)力并顯示在數(shù)字顯示器上。各個(gè)單元被插入到緊固在兩側(cè)的雙跨框架中。測(cè)試設(shè)備中使用的所有制動(dòng)部件都是原車(chē)部件。踏板力在制動(dòng)主缸驅(qū)動(dòng)連桿測(cè)量并顯示在數(shù)字顯示器上。實(shí)驗(yàn)結(jié)果與討論：使用公式計(jì)算各種粘度的值：V=HFρGD32hfv使用公式計(jì)算各種粘度的值：V=HFρGD32hfvV：粘度hf：毛細(xì)管高度ρ：流體的密度g:由于重力加速度D：孔的直徑V:速度圖三：流體粘度-溫度關(guān)系從圖3中可以看出臟的流體具有最高的粘度，其次是較低的流體，清潔液和肥皂溶液。從圖2所示的結(jié)果和表1所示的粘度測(cè)試中，顯示隨著溫度的升高肥皂溶液是粘度和粘度穩(wěn)定性最好的流體。然而，它與其它液體不兼容，很難與其他制動(dòng)液混合，并且有一個(gè)低沸點(diǎn)，這將不適合作為清洗制動(dòng)液的替代品。清潔制動(dòng)液的粘度和粘度隨溫度升高而增加。另一方面，它滿(mǎn)足了表1中顯示的一個(gè)良好的流體制動(dòng)系統(tǒng)中應(yīng)具有的所有要求，也滿(mǎn)足了根據(jù)馬德（1972）和納尼等人（1