汽车专业外语058课件

ElectronicFuelInjectionSystem电控燃油喷射系统Unit12EFIhasthejobofsupplyingairfuelmixturetotheengine.Inordertogetacleaneremission,EFIisapplied.Threesubsystems:airinductionsystem,

fueldeliverysystem,andelectroniccontrolsystem.IntroductionComponents:AircleanerAirflowmeterThrottlevalveAirintakechamberIntakemanifoldrunnerIntakevalveAirinductionsystemWhenthethrottlevalveisopened,airflowthroughtheaircleaner(ACL),throughtheairflowmeter(AFM),pastthethrottlevalve,andthroughtheintakemanifoldrunnertotheintakevalve.Airdeliveredtotheengineisafunctionofdriver’sdemand.Asthethrottlevalveisopenedfurther,moreairisallowedtoentertheenginecylinders.AirflowmeterAirinductionsystemItisadeviceformeasuringthevolumeofairenteringtheengine.Someusespring-loadedvanewhileothersuseahotwireorheatedfilamenttosenseairflow.ThrottlevalveAirinductionsystemThevalvethatregulateshowmuchairenterstheengine.Thegaspedalinourcarisconnectedtothethrottlevalve.Soactuallythegaspedalisaairpedal.AirintakechamberAirinductionsystemPreventspulsationoftheintakeair,andalsopreventstheinterferenceineachcylinder.FueldeliverysystemComponents:FueltankFuelpumpFuelfilterFueldeliverypipeFuelinjectorFuelpressureregulatorPulsationdamperFuelreturnpipeFuelisdeliveredfromfueltanktotheinjectorbyfuelpump,andthecontaminantsarefilteredoutbyfuelfilter,andthefuelpressureismaintainedataconstantvaluebyfuelpressureregulator.Anyfuelisnotdeliveredtotheintakemanifoldbytheinjectorisreturnedtothetankthoughafuelreturnpipe.FueldeliverysystemFuelpumpNormallylocatedinsidethefueltank.Itcandelivermorefuelthantheenginerequiresundermaximumoperatingconditions.Electricalfuelpumpcaneliminatetheproblemofvaporlockingthatcanbeaproblemforengineswithmechanicalfuelpumps.FueldeliverysystemFuelfilterTofilter/strainanycontamination/sediment/impurityfromgettingintothefuelsystem.It’sbasicpartsarestrainer,paperelementandsupportplate.FueldeliverysystemInjectorAnelectronicallycontrolledvalve.Whentheinjectorisenergized,anelectromagnetmovesaplungerthatopensthevalve,allowingthepressurizedfueltosquirtoutthroughatinynozzle.FueldeliverysystemFuelpressureregulatorAdjuststhepressureofthefuelfromthefuellinetoaconstantpressurehigherthanthepressureinsidetheintakemanifold,andtheexcessfuelisreturnedtothefueltankthroughthereturnpipe.Normallyintherangeof250-400kPaNewwordsCombustible易燃旳Emission排放（物）Vane叶片Filament灯丝，细丝Pulsation脉冲Interference干涉，冲突Contaminant污染物Pollutant污染物Sediment沉淀物Impurity杂质Strainer过滤网Electromagnet电磁铁Plunger活塞，柱塞Squirt喷射喷射器Nozzle喷嘴Fluctuation脉动，波动Excess过量旳；过分，过分Diaphragm隔膜，膜片Trigger开启装置；开启Solenoid电磁线圈ElectronicControlSystemComponents:EnginesensorsElectroniccontrolunitFuelinjectorassembliesRelatedwiringDeterminespreciselyhowmuchfuelneedstobedeliveredbytheinjector.TheECUturnstheinjectoronforapreciseamountoftime,referredtoasinjectionpulsewidthorinjectionduration,todelivertheproperairfuelmixturetotheengine.ElectronicControlSystemPulsewidthWhat’sthepulsewidth?Theamountoftimethefuelinjectorkeepsopen.Thepulsewidthisdeterminedbytheengine’sECU,anddependsontheenginetemperature,theengineloadandtheinformationfromtheoxygen(Lambda)sensor.ElectronicControlSystemElectronicsparkadvanceESAisprogrammedwithdataforoptimumignitiontimingunderalloperatingconditions.Usingthedataprovidedbythesensorswhichmonitorvariousenginefunctions(RPM,CoolantTemp.,etal.),theECUtriggersthesparkattherighttime.WorkingprocessAirenterstheenginethroughairinductionsystemwhereitismeasuredbytheairflowmeter.Beforetheairflowsintothecylinder,fuelismixedintotheairbythefuelinjector.TheECUpulsestheinjectorbyswitchingtheinjectorground(GND)circuitonandoff.Whentheinjectoristurnedon,itopens,sprayingatomizedfuelatthebacksideofintakevalve.TheECUsignalstheinjectortodeliverjustenoughfueltoachieveanidealairfuelratioof14.7:1.NewwordsPulse脉冲；调整Circuit电路，线路Correction修正，改正Throttlevalve节气门Intake

manifoldrunner

进气歧管Airintakechamber进气室Fuelpressureregulator压力调整器

Fuelreturnpipe回油管Pulsationdamper脉动衰减器Vaporlocking气阻Pulsewidth脉冲宽度Injectionduration喷油连续时间Airfuelratio空燃比EFI电控燃油喷射AFM空气流