电气与信息学院自动化专业毕业设计论文外文翻译电子动力转向系统的研究与设计.docx
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电气与信息学院自动化专业毕业设计论文外文翻译电子动力转向系统的研究与设计
电气与信息学院自动化专业毕业设计(论文)外文翻译
ElectonicpowersteeringsystemResearchandDesign
电子动力转向系统的研究与设计
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Electronicpowersteeringsystem
Whatitis
Electricallypoweredsteeringusesanelectricmotortodriveeitherthepowersteeringhydraulicpumporthesteeringlinkagedirectly.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"circuitthatsharesthesamehousingconvertsthesignalsfromthetorquesensorandrotationsensorintosignalsthecontrolelectronicscanprocess.
Inputsfromthesteeringsensoraredigestedbyamicroprocessorcontrolunitthatalsomonitorsinputfromthevehicle'sspeedsensor.Thesensorinputsarethencomparedtodeterminehowmuchpowerassistisrequiredaccordingtoapreprogrammed"forcemap"inthecontrolunit'smemory.Thecontrolunitthensendsouttheappropriatecommandtothe"powerunit"whichthensuppliestheelectricmotorwithcurrent.Themotorpushestheracktotherightorleftdependingonwhichwaythevoltageflows(reversingthecurrentreversesthedirectionthemotorspins).Increasingthecurrenttothemotorincreasestheamountofpowerassist.
Thesystemhasthreeoperatingmodes:
a"normal"controlmodeinwhichleftorrightpowerassistisprovidedinresponsetoinputfromthesteeringtorqueandrotationsensor'sinputs;a"return"controlmodewhichisusedtoassiststeeringreturnaftercompletingaturn;anda"damper"controlmodethatchangeswithvehiclespeedtoimproveroadfeelanddampenkickback.
Ifthesteeringwheelisturnedandheldinthefull-lockpositionandsteeringassistreachesamaximum,thecontrolunitreducescurrenttotheelectricmotortopreventanoverloadsituationthatmightdamagethemotor.Thecontrolunitisalsodesignedtoprotectthemotoragainstvoltagesurgesfromafaultyalternatororchargingproblem.
Theelectronicsteeringcontrolunitiscapableofself-diagnosingfaultsbymonitoringthesystem'sinputsandoutputs,andthedrivingcurrentoftheelectricmotor.Ifaproblemoccurs,thecontrolunitturnsthesystemoffbyactuatingafail-saferelayinthepowerunit.Thiseliminatesallpowerassist,causingthesystemtorevertbacktomanualsteering.AdashEPSwarninglightisalsoilluminatedtoalertthedriver.Todiagnosetheproblem,atechnicianjumpstheterminalsontheservicecheckconnectorandreadsoutthetroublecodes.
clickheretoseeabigger
Electricpowersteeringsystemspromiseweightreduction,fuelsavingsandpackageflexibility,atnocostpenalty.
Europe'shighfuelpricesandsmallervehiclesmakeafertiletestbedforelectricsteering,atechnologythatpromisesautomakersweightsavingsandfueleconomygains.Andinashorttime,electricsteeringwillmakeittotheU.S.,too."It'sjustjustamatteroftime,"saysAlyBadawy,directorofresearchanddevelopmentforDelphiSaginawSteeringSystemsinSaginaw,Mich."Theissuewascostandthat'sbehindusnow.By2002hereintheU.S.thecostofelectricpowersteeringwillabsolutelybeawashoverhydraulic."
Today,electricandhybrid-poweredvehicles(EV),includingToyota'sPriusandGM'sEV-1,aretheperfectdomainforelectricsteering.Butby2010,aTRWInc.internalstudyestimatesthatoneoutofeverythreecarsproducedintheworldwillbeequippedwithsomeformofelectrically-assistedsteering.TheCleveland-basedsupplierclaimsitsnewsteeringsystemscouldimprovefueleconomybyupto2mpg,whileenhancinghandling.Therearetruebottom-linebenefitsaswellforautomakersbyreducingoverallcostsanddecreasingassemblytime,sincethere'snoneedforpumps,hosesandfluids.
Anotherclaimedadvantageisshorteneddevelopmenttime.Forinstance,aDelphigroupdevelopedE-TUNE,aride-and-handlingsoftwarepackagethatcanberunoffalaptopcomputer."Theycantakethatcomputerandplugitin,attachittothecontrollerandchangeallthehandlingparameters--effortlevel,returnability,damping--onthefly,"Badawysays."Itusedtotakemonths."DelphihasoneOEMcustomerthatshouldstartlow-volumeproductionin'99.Electricsteeringunitsarenormallyplacedinoneofthreepositions:
column-drive,pinion-driveandrack-drive.Whichsystemwillbecomethenormisstillunclear.Shortterm,OEMswillchoosethesteeringsystemthatiseasiesttointegrateintoanexistingplatform.Obviously,greaterpotentialcomesfromdesigningthesystemintoanall-newplatform."Wehaveallthreedesignsunderconsideration,"saysDr.HermanStrecker,groupvicepresidentofsteeringsystemsdivisionatZFinSchwaebischGmuend,Germany."It'suptothemarketandOEMswhichversionfinallywillbeusedandmanufactured.""Thelargemanufacturershaveallgrabbedholdofwhattheyconsideracoretechnology,"explainsJamesHandysides,TRWvicepresident,electricallyassistedsteeringinSterlingHeights,Mich.Hiscompanyoffersaportfolioofelectricsteeringsystems(hybridelectric,rack-,pinion-,andcolumn-drive).TRWoriginallyconcentratedonwhatitstillbelievesisthepurestengineeringsolutionforelectricsteering--therack-drivesystem.Thesystemissometimesrefertoasdirectdriveorball/nutdrive.Still,thiswinterTRWhedgeditsbet,formingajointventurewithLucasVarity.TheBritishsupplierreceived$50millioninexchangeforitselectriccolumn-drivesteeringtechnologyandassets.InitialproductionofthecolumnandpiniondriveelectricsteeringsystemsisexpectedtobegininBirmingham,England,in2000.
"Whatwelackisthecredibilityinthesteeringmarket,"saysBrendanConner,managingdirector,TRW/LucasVarityElectricSteeringLtd."ThecombinationwithTRWprovidesuswithagoodopportunityforustobridgethatgap."LucasVaritycurrentlyhasexperimentalsystemson11differentvehicletypes,mostlyEuropean.TRWiscurrentlysupplyingitsEASsystemsforFordandChryslerEVsinNorthAmericaandforGM'snewOpelAstra.
In1995,accordingtoDelphi,traditionalhydraulicpowersteeringsystemswereon7596ofallvehiclessoldglobally.That37-millionvehiclepoolconsumesabout10milliongallonsinhydraulicfluidthatcouldbesuperfluous,ifelectricsteeringreallytakesoff.
Thepresentinventionrelatestoanelectricallypowereddrivemechamsmforprovidingpoweredassistancetoavehiclesteeringmechanism.Accordingtooneaspectofthepresentinvention,thereisprovidedanelectricallypowereddrivenmechanismforprovidingpoweredassistancetoavehiclesteeringmechanismhavingamanuallyrotatablememberforoperatingthesteeringmechanism,thedrivemechanismincludingatorquesensoroperabletosensetorquebeingmanuallyappliedtotherotatablemember,anelectricallypowereddrivemotordrivinglyconnectedtotherotatablememberandacontrollerwhichisarrangedtocontrolthespeedanddirectionofrotationofthedrivemotorinresponsetosignalsreceivedfromthetorquesensor,thetorquesensorincludingasensorshaftadaptedforconnectiontotherotatablemembertoformanextensionthereofsothattorqueistransmittedthroughsaidsensorshaftwhentherotatablememberismanuallyrotatedandastraingaugemountedonthesensorshaftforproducingasignalindicativeoftheamountoftorquebeingtransmittedthroughsaidshaft.Preferablythesensorshaftisnon-rotatablymountedatoneaxialendinafirstcouplingmemberandisnon-rotatablymountedatitsoppositeaxialendinasecondcouplingmember,thefirstandsecondcouplingmembersbeinginter-engagedtopermitlimitedrotationtherebetweensothattorqueunderapredeterminedlimitistransmittedbythesensorshaftonlyandsothattorqueabovesaidpredeterminedlimitistransmittedthroughthefirstandsecondcouplingmembers.Thefirstandsecondcouplingmembersarepreferablyarrangedtoactasabridgefordrivinglyconnectingfirstandsecondportionsoftherotatingmembertooneanother.Preferablythesensorshaftisofgenerallyrectangularcross-sectionthroughoutthemajorityofitslength.PreferablythestraingaugeincludesoneormoreSAWresonatorssecuredtothesensorshaft.Preferablythemotorisdrivinglyconnectedtotherotatablememberviaaclutch.Preferablythemotorincludesagearboxandisconcentricallyarrangedrelativ