专业英语ppt课件4-U3TA

UNIT3FUELINJECTIONSYSTEMSTEXTAElectronicFuelInjectionSystems,PROFESSIONALENGLISH,UNIT3FUELINJECTIONSYSTEMSTEXTAElectronicFuelInjectionSystemsPulseFuelInjectionPulseFuelInjectionSystemComponentsAirinductionsystemFueldeliverysystemEnginecontrolcomputerElectronicSensorsContinuousInjectionSystems(CIS),本次课学习内容,本次课学习目标,掌握电控燃油喷射系统主要部件的英文名称、主要部件的作用及工作原理掌握常用术语（phrasesandexpressions）了解相关术语（relatedterms）提高翻译能力,NEWWORDS,manifoldmnifouldn.歧管manipulatemnipjuleitv.操纵，控制，支配venturiventu:rin.文丘里管，喉管driveabilitydraivbilitin.运行性能，操纵性能laglgn.滞后，迟后，惯性，惰性turbochargert:bout:n.涡轮增压器，增压器compressorkmpresn.压气机，压缩机，压缩装置sensorsensn.传感器passagewaypsiwein.通路psi(=poundpersquareinch)磅力/平方英寸（lbf/in2）injectorinektn.喷油器，注射器,circuits:kitn.电（气，油，回）路complexitykmpleksitin.复杂性plugplgn.塞子，堵头，插头energizeenaizv.通电，励磁distributordistribjutn.分配器，分电器throttlertln.节气门relayrilei,ri:lein.继电器，转播；v.中继，转播barometricbroumetrikn.大气压力的vortexv:teksn.涡流，涡旋，旋风distinctlydistiktliad.显然，清楚地，明明spawnsp:nv.产卵,pulsefuelinjection脉冲燃油喷射continuousfuelinjection连续燃油喷射throttlebodyinjection节气门体喷射single-pointinjection单点喷射centralfuelinjection中央喷射multi-pointsystems多点喷射multi-portinjection多点喷射tunedintakerunners调谐进气管intakemanifold进气歧管airinductionsystem进气系统,PHRASESANDEXPRESSIONS,fueldeliverysystem供油系统aircleaner空气滤清器electricfuelpump电动燃油泵pressureregulator压力调节器fuelinletline进油管fueltank燃油箱fuelinjector喷油器fuelrail燃油分配管，油轨ignitioncoil点火线圈Hall-effectswitch霍尔效应开关barometricpressure大气压力,heatedwire热线式airvalve空气阀式（=vanetype叶片式）Karmannvortex卡曼涡旋式,ElectronicFuelInjectionFuelinjectionsystemsdeliverfuelbyforcingitintotheincomingairstream（Fig.3-1）.Fuelinjectionsystemsactuallymeasuretheincomingairandpressurizethefueltodeliveritinpreciseamountsbaseddirectlyonthatmeasurement.Becausefuelisdeliveredtothemanifoldunderpressure,thequantityoffueldeliveredcanbemorepositivelycontrolled.Withthismorepositivecontrol,fueldeliverycanbemoreeasilymanipulatedtomeettheuniquedemandsofextremeoperatingconditions.Thisresultsingreaterefficiencyoverawiderrangeofoperation.,Intheelectronicinjectionsystem,theair-fuelmixtureiscontrolledinoneoftwoways.Theinjectormaybeopenedandclosedbyelectricalsignals.Thisisapulsefuelinjectionsystem.Intheothertypeofsystem,theinjectorisforcedopenbyfuelpressure.Fuelpressureiscontrolledbyanelectroniccontroldevice,orbyanairflowmeteringvalve,dependingonthesystem.Thisisthecontinuousfuelinjectionsystem.,Fig.3-1Fuelinjectorismountedontheintakemanifold,1.PulseFuelInjectionInpulseinjectionsystems,therateoffuelflowthroughtheinjectorsremainsconstant.Thetotalamountoffueldeliveredisdeterminedbythelengthoftimetheinjectorsareheldopen.Systemsareclassifiedbythetypeoftimingsequenceusedandthelocationoftheinjectors.TypesofPulseFuelInjectionSystemsThenextsectionwilldiscusscommonfuelinjectionsystemswhicharetypicalofthepulsesystemsnowinuse.Thepulseinjectionsystemisusuallyelectronicallycontrolled.Althoughthereareanumberofdesigndifferencesbetweenvariouspulsefuelinjectionsystems,theoperatingprinciplesareverysimilar.Thethrottlebodyinjectionsystemusesanassemblycontainingoneortwofuelinjectors.Theassemblyismountedattheentrancetotheintakemanifoldandinjectsfuelaheadofthethrottlevalve.Thesesystemsarealsocalledsingle-pointinjectionorcentralfuelinjection.,Multi-pointsystems,alsocalledmulti-portinjectionsystems,deliverfuelattheengineintakeportsneartheintakevalves.Thismeansthattheintakemanifolddeliversonlyair,incontrasttocarburetorsorsingle-pointfuelinjectionsystemsinwhichtheintakemanifoldcarriestheair-fuelmixture1.Asaresult,thesesystemsofferthefollowingadvantages:greaterpowerbyavoidingventurilossesasinacarburetor,andbyallowingtheuseoftunedintakerunnersforbettertorquecharacteristicsimproveddriveabilitybyreducingthethrottle-changelagwhichoccurswhilethefueltravelsfromthethrottlebodytotheintakeports2increasedfueleconomybyavoidingcondensationoffueloninteriorwallsoftheintakemanifold(manifoldwetting)simplifiedturbochargerapplications;theturbochargercompressorneedonlyhandleair.,PulseFuelInjectionSystemComponentsThetypicalpulsesystemcanbebrokenintothreebasicparts:Airinductionsystem.Fueldeliverysystem.Electroniccontrolsystem(includingenginecontrolcomputerandelectronicsensors).AirinductionsystemTheairinductionsystemconsistsofanaircleanerassembly,throttlebody,andintakemanifold.Thethrottlebodysectioncontainsthethrottlevalve,whichisopenedandclosedbythedrivertocontroltheamountofairenteringtheintakemanifold.Onthrottlebodyfuelinjectionsystems,thethrottlebodyalsocontainsthefuelinjectioncomponentsasdiscussedearlier.Theintakemanifoldformsaclosedpassagewaybetweenthethrottlebodyandthecylinderhead.,Fig.3-2Fueldeliverysystem,FueldeliverysystemThefueldeliverysystem（Fig.3-2）providesthefuelwhichmixeswiththeair.Pressureisprovidedbyanelectricfuelpump.Somesystemsusetwopumps:alow-pressurefuelpumpthatdeliversfueltoanotherpump,whichdevelopsthepressure.,FuelPressureRegulatorsPressureinsomethrottlebodyfuelinjectionsystemsisaslowas7psi,whilesomemulti-portsystemscanreach60psi(55kPato380kPa)ormore.Injectionsystempressureiscontrolledbyapressureregulator.Theregulatorcontrolspressurebybleedingexcessfuelbackintothefuelinletlineorthefueltank.Pressureregulatorsonmulti-portfuelinjectionsystemsareusuallyconnectedbyahosetotheintakemanifold.FuelInjectorsThefuelinjectorsreceivefuelfromthepumporpumpsandpressureregulatorandsprayitintotheintakemanifold.Injectorscanbepartofathrottlebody,orinstalledintheintakemanifoldandconnectedtothefuelsystemthroughafuelrail.Thefuelrailisarigidpieceofsteeltubingthatfeedsfueltotheinjectors.Somesystemsuseflexiblehosestoconnecttheinjectorstothefuelrail.,EnginecontrolcomputerEnginecontrolcomputersareconstructedusingmanydifferentelectroniccircuitsandcomponents.Sizeandcomplexityvariesdependinguponthesystem.Moderncomputerscontrolmanyotherenginesystemsinadditiontothefuelinjectors.Thecomputerisusuallylocatedinaprotectedareaawayfromenginevibrationandheat,andisconnectedtotherestoftheinjectionsystembymeansofasealedwiringharnessplug.Thecomputerreceivessignalsfromanumberofsensorswhenevertheengineisrunning.Fromthisinput,thecomputerevaluatesenginefuelneedsandadjustsinjectorpulsewidthaccordingly.Somecomputersalsoenergizethefuelpumporpumpsfor2-5secondstopressurizethefuelsystembeforeacoldstart.Manyfuelinjectionsystemsdothisinplaceofacoldstartvalve.,ElectronicSensorsTheelectronicsensorsmonitor(check)variousenginefunctionsandfeedthisinformationtothecomputer.Thenumberandtypesofsensorsvarywiththesystem.OxygenSensorTheoxygensensormonitorstheamountofoxygenintheenginesexhaustgases.Astheoxygencontentintheexhaustgaseschanges,thevoltagesignalproducedbythesensoralsochanges.Thecomputerusessignalsfromtheoxygensensortocontroltheair-fuelmixture.Theoxygensensorisgenerallymountedintheexhaustmanifold.Mostelectronicfuelinjectionsystemsrelyonthissensorformuchoftheenginesoperatinginformation.,EngineSpeedSensorTheenginespeedsensormonitorsengineRPM.Manyspeedsensorsaremountedinthedistributor，wheretheyobtainasignalfromtherotatingdistributorshaft.Insomecases,theignitioncoilorHall-effectswitchprovidesthesignaltothecomputer.Inothersystems,thespeedsensorismountedsothatitcanmonitorcrankshaftorcamshaftrotation.Thesespeedsensorsalsoindicatethecrankshaftandcamshaftpositionsothatthecomputercanopentheinjectorbeforetheintakevalveopens.Thisinformationisutilizedbythecomputer(alongwithothersensorinputs)tohelpdetermineinjectorpulsetimingandpulsewidth.ThrottlePositionSensorThrottlepositionisrelayedtothecomputerbythethrottlepositionsensor.Throttlepositionsensorsareinstalledonthethrottlebody,andareusedtomonitorthemovementofthethrottlevalve.Theycanberesistancetypes.Resistance,sensorscontainvariableresistanceunitswhichsendavaryingsignaltothecomputer,dependingonthrottleposition.ManifoldAbsolutePressureSensorEngineloadistransmittedtothecomputerbymeansofanintakemanifoldabsolutepressuresensor.Thesensorconvertsmanifoldvacuumintoasmallelectricalsignal.Thisinputallowsthecomputertoincreasefuelsupplywhentheengineisunderloadandneedsarichermixture,anddecreasefuelsupplywhenengineloadislight.BarometricPressureSensorManyinjectionsystemshaveasensortomeasurethepressureoftheoutsideair,usuallycalledatmosphericorbarometricpressure.Barometricpressureiscomparedwithmanifoldvacuumbythecomputertomorecloselymonitorengineload.Theinputofthissensorisimportantwhenthevehicleisdriventohigherandloweraltitudes.Thissensorissometimescombinedwiththemanifoldvacuumsensorintoasingleunit.,TemperatureSensorTemperaturehasagreateffectontheoperationofthefuelinjectionsystem.Toovercomethetendencyofcoldfueltocondenseintoannoncombustibleliquid,coldenginesmusthavearichermixtureiftheyaretorunproperly.Everyinjectionsystemhasatemperaturesensortomeasureenginecoolanttemperature.Manyinjectionsystemshaveanadditionalsensortomeasurethetemperatureoft