外文翻译电子动力转向系统.doc
1ElectronicpowersteeringsystemWhatitisElectricallypoweredsteeringusesanelectricmotortodriveeitherthepowersteeringhydraulicpumporthesteeringlinkagedirectly.Thepowersteeringfunctionisthereforeindependentofenginespeed,resultinginsignificantenergysavings.Howitworks:Conventionalpowersteeringsystemsuseanengineaccessorybelttodrivethepump,providingpressurizedfluidthatoperatesapistoninthepowersteeringgearoractuatortoassistthedriver.Inelectro-hydraulicsteering,oneelectricallypoweredsteeringconceptusesahighefficiencypumpdrivenbyanelectricmotor.Pumpspeedisregulatedbyanelectriccontrollertovarypumppressureandflow,providingsteeringeffortstailoredfordifferentdrivingsituations.Thepumpcanberunatlowspeedorshutofftoprovideenergysavingsduringstraightaheaddriving(whichismostofthetimeinmostworldmarkets).Directelectricsteeringusesanelectricmotorattachedtothesteeringrackviaagearmechanism(nopumporfluid).Avarietyofmotortypesandgeardrivesispossible.Amicroprocessorcontrolssteeringdynamicsanddrivereffort.Inputsincludevehiclespeedandsteering,wheeltorque,angularpositionandturningrate.WorkingInDetail:A"steeringsensor"islocatedontheinputshaftwhereitentersthegearboxhousing.Thesteeringsensorisactuallytwosensorsinone:a"torquesensor"thatconvertssteeringtorqueinputanditsdirectionintovoltagesignals,anda"rotationsensor"thatconvertstherotationspeedanddirectionintovoltagesignals.An"interface"circuitthatsharesthesamehousingconvertsthesignalsfromthe2torquesensorandrotationsensorintosignalsthecontrolelectronicscanprocess.Inputsfromthesteeringsensoraredigestedbyamicroprocessorcontrolunitthatalsomonitorsinputfromthevehiclesspeedsensor.Thesensorinputsarethencomparedtodeterminehowmuchpowerassistisrequiredaccordingtoapreprogrammed"forcemap"inthecontrolunitsmemory.Thecontrolunitthensendsouttheappropriatecommandtothe"powerunit"whichthensuppliestheelectricmotorwithcurrent.Themotorpushestheracktotherightorleftdependingonwhichwaythevoltageflows(reversingthecurrentreversesthedirectionthemotorspins).Increasingthecurrenttothemotorincreasestheamountofpowerassist.Thesystemhasthreeoperatingmodes:a"normal"controlmodeinwhichleftorrightpowerassistisprovidedinresponsetoinputfromthesteeringtorqueandrotationsensorsinputs;a"return"controlmodewhichisusedtoassiststeeringreturnaftercompletingaturn;anda"damper"controlmodethatchangeswithvehiclespeedtoimproveroadfeelanddampenkickback.Ifthesteeringwheelisturnedandheldinthefull-lockpositionandsteeringassistreachesamaximum,thecontrolunitreducescurrenttotheelectricmotortopreventanoverloadsituationthatmightdamagethemotor.Thecontrolunitisalsodesignedtoprotectthemotoragainstvoltagesurgesfromafaultyalternatororchargingproblem.Theelectronicsteeringcontrolunitiscapableofself-diagnosingfaultsbymonitoringthesystemsinputsandoutputs,andthedrivingcurrentoftheelectricmotor.Ifaproblemoccurs,thecontrolunitturnsthesystemoffbyactuatingafail-saferelayinthepowerunit.Thiseliminatesallpowerassist,causingthesystemtorevertbacktomanualsteering.AdashEPSwarninglightisalsoilluminatedtoalertthedriver.Todiagnosetheproblem,atechnicianjumpstheterminalsontheservicecheckconnectorandreadsoutthetroublecodes.3clickheretoseeabiggerElectricpowersteeringsystemspromiseweightreduction,fuelsavingsandpackageflexibility,atnocostpenalty.Europeshighfuelpricesandsmallervehiclesmakeafertiletestbedforelectricsteering,atechnologythatpromisesautomakersweightsavingsandfueleconomygains.Andinashorttime,electricsteeringwillmakeittotheU.S.,too."Itsjustjustamatteroftime,"saysAlyBadawy,directorofresearchanddevelopmentforDelphiSaginawSteeringSystemsinSaginaw,Mich."Theissuewascostandthatsbehindusnow.By2002hereintheU.S.thecostofelectricpowersteeringwillabsolutelybeawashoverhydraulic."Today,electricandhybrid-poweredvehicles(EV),includingToyotasPriusandGMsEV-1,aretheperfectdomainforelectricsteering.Butby2010,aTRWInc.internalstudyestimatesthatoneoutofeverythreecarsproducedintheworldwillbeequippedwithsomeformofelectrically-assistedsteering.TheCleveland-basedsupplierclaimsitsnewsteeringsystemscouldimprovefueleconomybyupto2mpg,whileenhancinghandling.Therearetruebottom-linebenefitsaswellforautomakersbyreducingoverallcostsanddecreasingassemblytime,sincetheresnoneedforpumps,hosesandfluids.Anotherclaimedadvantageisshorteneddevelopmenttime.Forinstance,aDelphigroupdevelopedE-TUNE,aride-and-handlingsoftwarepackagethatcanberunoffalaptopcomputer."Theycantakethatcomputerandplugitin,attachittothecontrollerandchangeallthehandlingparameters-effortlevel,returnability,damping-onthefly,"Badawysays."Itusedtotakemonths."DelphihasoneOEMcustomerthatshouldstartlow-volumeproductionin99.Electricsteeringunitsarenormallyplacedinoneofthreepositions:column-drive,pinion-driveandrack-drive.Whichsystemwillbecomethenormisstillunclear.Shortterm,OEMswillchoosethesteeringsystemthatiseasiesttointegrateintoanexistingplatform.Obviously,4greaterpotentialcomesfromdesigningthesystemintoanall-newplatform."Wehaveallthreedesignsunderconsideration,"saysDr.HermanStrecker,groupvicepresidentofsteeringsystemsdivisionatZFinSchwaebischGmuend,Germany."ItsuptothemarketandOEMswhichversionfinallywillbeusedandmanufactured.""Thelargemanufacturershaveallgrabbedholdofwhattheyconsideracoretechnology,"explainsJamesHandysides,TRWvicepresident,electricallyassistedsteeringinSterlingHeights,Mich.Hiscompanyoffersaportfolioofelectricsteeringsystems(hybridelectric,rack-,pinion-,andcolumn-drive).TRWoriginallyconcentratedonwhatitstillbelievesisthepurestengineeringsolutionforelectricsteering-therack-drivesystem.Thesystemissometimesreferedtoasdirectdriveorball/nutdrive.Still,thiswinterTRWhedgeditsbet,formingajointventurewithLucasVarity.TheBritishsupplierreceived$50millioninexchangeforitselectriccolumn-drivesteeringtechnologyandassets.InitialproductionofthecolumnandpiniondriveelectricsteeringsystemsisexpectedtobegininBirmingham,England,in2000."Whatwelackisthecredibilityinthesteeringmarket,"saysBrendanConner,managingdirector,TRW/LucasVarityElectricSteeringLtd."ThecombinationwithTRWprovidesuswithagoodopportunityforustobridgethatgap."LucasVaritycurrentlyhasexperimentalsystemson11differentvehicletypes,mostlyEuropean.TRWiscurrentlysupplyingitsEASsystemsforFordandChryslerEVsinNorthAmericaandforGMsnewOpelAstra.In1995,accordingtoDelphi,traditionalhydraulicpowersteeringsystemswereon7596ofallvehiclessoldglobally.That37-millionvehiclepoolconsumesabout10milliongallonsinhydraulicfluidthatcouldbesuperfluous,ifelectricsteeringreallytakesoff.Thepresentinventionrelatestoanelectricallypowereddrivemechamsmforprovidingpoweredassistancetoavehiclesteeringmechanism.Accordingtooneaspectofthepresentinvention,thereisprovidedanelectricallypowereddrivenmechanismforprovidingpoweredassistancetoavehiclesteeringmechanismhavingamanuallyrotatablememberforoperatingthesteeringmechanism,thedrivemechanismincludingatorquesensoroperabletosensetorquebeingmanuallyappliedtotherotatablemember,anelectricallypowereddrivemotordrivinglyconnectedtotherotatablememberandacontrollerwhichisarrangedtocontrolthespeedanddirectionofrotationofthedrivemotorinresponsetosignalsreceivedfromthetorquesensor,thetorquesensorincludingasensorshaftadaptedforconnectiontotherotatablemembertoformanextensionthereofsothattorqueistransmittedthroughsaidsensorshaftwhentherotatablememberismanuallyrotatedandastraingaugemountedonthesensorshaftforproducingasignalindicativeoftheamountoftorquebeingtransmittedthroughsaidshaft.Preferablythesensorshaftisnon-rotatablymountedatoneaxialendinafirstcouplingmemberandisnon-rotatablymountedatitsoppositeaxialendinasecondcouplingmember,thefirstandsecondcouplingmembersbeinginter-engagedtopermitlimitedrotationtherebetweensothattorqueunderapredeterminedlimitistransmittedbythesensorshaftonlyandsothattorqueabovesaidpredeterminedlimitistransmittedthroughthefirstandsecondcouplingmembers.Thefirstandsecondcouplingmembersarepreferablyarrangedtoactasa