自动化专业毕业设计论文外文翻译电子动力转向系统.docx

自动化专业毕业设计论文外文翻译电子动力转向系统.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

自动化专业毕业设计（论文）外文翻译

Electronicpowersteeringsystem

Whatitis

ElectricallypoweredsteeringusesanelectricmotortodriveeitherthepowersteeringHYPERLINK"\t"_top"hydraulicpumporthesteeringlinkagedirectly.Thepowersteeringfunctionisthereforeindependentofenginespeed,resultinginsignificantenergysavings.

Howitworks:

ConventionalpowerHYPERLINK"\t"_top"steeringsystemsuseanengineaccessorybelttodrivethepump,providingpressurizedfluidthatoperatesapistoninthepowersteeringgearoractuatortoassistthedriver.Inelectro-hydraulicsteering,oneelectricallypoweredsteeringconceptusesahighefficiencypumpdrivenbyanHYPERLINK"\t"_top"electricmotor.Pumpspeedisregulatedbyanelectriccontrollertovarypumppressureandflow,providingsteeringeffortstailoredfordifferentdrivingsituations.Thepumpcanberunatlowspeedorshutofftoprovideenergysavingsduringstraightaheaddriving（whichismostofthetimeinmostworldmarkets）.DirectelectricsteeringusesanelectricmotorattachedtotheHYPERLINK"\t"_top"steeringrackviaagearmechanism（nopumporfluid）.Avarietyofmotortypesandgeardrivesispossible.Amicroprocessorcontrolssteeringdynamicsanddrivereffort.Inputsincludevehiclespeedandsteering,wheeltorque,angularpositionandturningrate.

WorkingInDetail:

A"steeringsensor"islocatedontheinputshaftwhereitentersthegearboxhousing.Thesteeringsensorisactuallytwosensorsinone:

a"torquesensor"thatconvertssteeringtorqueinputanditsdirectionintovoltagesignals,anda"rotationsensor"thatconvertstherotationspeedanddirectionintovoltagesignals.An"interface"circuitthatsharesthesamehousingconvertsthesignalsfromthetorquesensorandrotationsensorintosignalsthecontrolelectronicscanprocess.

Inputsfromthesteeringsensoraredigestedbyamicroprocessorcontrolunitthatalsomonitorsinputfromthevehicle'sHYPERLINK"\t"_top"speedsensor.Thesensorinputsarethencomparedtodeterminehowmuchpowerassistisrequiredaccordingtoapreprogrammed"forcemap"inthecontrolunit'smemory.Thecontrolunitthensendsouttheappropriatecommandtothe"HYPERLINK"\t"_top"powerunit"whichthensuppliestheelectricmotorwithcurrent.Themotorpushestheracktotherightorleftdependingonwhichwaythevoltageflows（reversingthecurrentreversesthedirectionthemotorspins）.Increasingthecurrenttothemotorincreasestheamountofpowerassist.Thesystemhasthreeoperatingmodes:

a"normal"controlmodeinwhichleftorrightpowerassistisprovidedinresponsetoinputfromthesteeringtorqueandrotationsensor'sinputs;a"return"controlmodewhichisusedtoassiststeeringreturnaftercompletingaturn;anda"damper"controlmodethatchangeswithvehiclespeedtoimproveroadfeelanddampenkickback.Ifthesteeringwheelisturnedandheldinthefull-lockpositionandsteeringassistreachesamaximum,thecontrolunitreducescurrenttotheelectricmotortopreventanoverloadsituationthatmightdamagethemotor.ThecontrolunitisalsodesignedtoprotectthemotoragainstvoltagesurgesfromafaultyHYPERLINK"\t"_top"alternatororchargingproblem.Theelectronicsteeringcontrolunitiscapableofself-diagnosingfaultsbymonitoringthesystem'sinputsandoutputs,andthedrivingcurrentoftheelectricmotor.Ifaproblemoccurs,thecontrolunitturnsthesystemoffbyactuatingafail-saferelayinthepowerunit.Thiseliminatesallpowerassist,causingthesystemtorevertbacktomanualsteering.AdashEPSwarninglightisalsoilluminatedtoalertthedriver.Todiagnosetheproblem,atechnicianjumpstheterminalsontheservicecheckconnectorandreadsouttheHYPERLINK"\t"_top"troublecodes.

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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.HYPERLINK"\t"_blank"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-rotatablymountedatoneaxialendinafirstcouplingmembe