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

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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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

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.Thesystemissometimesreferedtoasdirectdriveorball/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.Preferablythemotorincludesagearboxandisconcentricallyarrangedrelativetotherotatablemember.Variousaspectsofthepresentinventionwillhereafterbedescribed,withreferencetoth