1CaterpillarElectronicEngine卡特彼勒電控柴油機(jī)2發(fā)動(dòng)機(jī)控制模塊(ECM)各種傳感器(Sensors)噴油器監(jiān)視系統(tǒng)主要構(gòu)成部件31.電控柴油機(jī)的大腦

發(fā)動(dòng)機(jī)控制模塊（ECM）全權(quán)的發(fā)動(dòng)機(jī)電子控制記錄發(fā)動(dòng)機(jī)故障改進(jìn)的發(fā)動(dòng)機(jī)故障診斷方式發(fā)動(dòng)機(jī)的監(jiān)視和保護(hù)更多的程序定制功能基于兩個(gè)32位微處理器體系的ECM監(jiān)視發(fā)動(dòng)機(jī)運(yùn)行參數(shù)，由此提供精確的燃油計(jì)量和噴射正時(shí)控制。出色的燃油消耗、性能、耐久性、可靠性。5燃油進(jìn)口燃油出口E.C.M.J240針接口E.C.M.J140針接口Electronic電子Control 控制Module 模塊

Advanced高級(jí)Diesel 柴油Engine 發(fā)動(dòng)機(jī)Management管理系統(tǒng)燃油冷卻管道40針接口橡膠隔離加強(qiáng)的鋁合金密封盒體78ECM的主要功能PowerscomponentsControlstheengine

Monitorssensorinput9電子調(diào)速器發(fā)動(dòng)機(jī)邏輯控制空燃比圖扭矩圖關(guān)機(jī)油門速度正時(shí)齒輪理想轉(zhuǎn)速rpm扭矩校正空燃比校正實(shí)際轉(zhuǎn)速rpm到各噴油器的信號(hào)燃油噴射控制信號(hào)轉(zhuǎn)換傳感器大氣壓力、進(jìn)氣歧管壓力機(jī)油、燃油壓力排氣溫度、冷卻水溫命令轉(zhuǎn)速rpm10正時(shí)發(fā)動(dòng)機(jī)轉(zhuǎn)速供油量中冷器溫度30-25-20-15-10-5--25-20-15-10-52000-1750-1500-1250-1000-750--120-100-80-60-40-2011傳感器的輸入信息可以控制發(fā)動(dòng)機(jī)的運(yùn)行并顯示給操作者。壓力傳感器溫度傳感器位置傳感器速度傳感器2.ECM的輸入—傳感器12ThissensorprovidesenginespeedandcrankshaftpositioninformationtotheECM.Heavyhex-shapedaluminumbodyfordurabilityStraightthreado-ringmountforaleak-freeengineDeutschconnectorfortrouble-freeoperationSpeedTimingSensor13Incriticalapplications,backupsensorinsuresengineup-timeECMswitchestobackupwithoutinterruptioninengineoperationDualSpeedTimingSensors14SpeedTimingSensor(ActiveSensor)Theactivesensorincorporatesapoweredcircuitinthesensor.Thissensorhasthreewires.Thefirstwiresupplies13.2voltsfromtheECMtopowerthesensorboard.Thissupplyvoltageispreciselycontrolledto±0.5volts.ThesecondwireisagroundwirefromtheECMthatsuppliesazerovoltreference.ThethirdwireisthesignalvoltagetotheECM.15SensorreadsspecialtoothpatternoncamshaftgearSensorsendsasignaltotheECMaseachtoothpassesUniquepatternofteethindicateenginepositiontotheECMSpeedTimingSensorMounting16Simple,effectivedesignAllapplicationsutilizedualsensorsforreliabilitySpeedTimingSensor(PassiveSensor)Thepassivesensordoesnotincorporateactiveelectroniccircuitry.Thissensorisusedonthe3126Bengine.Thesensorhasapermanentmagnetandacoilofwireinside.Achangeinthemagneticfieldinducesavoltageintothesensor.TheECMreadstheincreasesanddecreasesinvoltagefromthesensorasasignal.17TemperaturesensorscontinuouslymonitorsystemtemperaturesandsendinformationtoECMHeavybrassbodyfortrouble-freeserviceLargehexonbodyforeasyinstallationandremovalStraightthreado-ringmountforaleak-freeengineTemperatureSensors—Oil,Coolant,Fuel18ProvidescriticalinformationtotheECMforfuelrateadjustmentsCarbonfiberbodypreventshigherenginetemperaturesfromaffectingtemperaturereadingsofintakeairStraightthreado-ringmountforaleak-freeengineTemperatureSensor—AirIntake19TemperatureSensorCircuitsThecoolanttemperaturesensormeasuresthetemperatureofthecoolantandsendsaDCsignaltotheECM.TheECMusesthisinformationtodetermineinjectiontiming,adjustthefuelratecalculation,andprotecttheenginefromoverheating.TheoiltemperaturesensormeasuresthetemperatureoftheenginelubricatingoilandsendsaDCsignaltotheECM.TheECMusesthisinformationtoprotecttheenginefromdamagefromlackoflubrication.Thefueltemperaturesensormeasuresthetemperatureoftheenginefuel,andsendsaDCsignaltotheECM.TheECMusesthisinformationtoadjustthefuelratecalculationandforfueltemperaturepowercorrection.20TemperatureSensorComponentsThetemperaturesensorsmeasurechangesintemperatureandsendavariableDCvoltagebacktotheECM.Thesensorshavethreewires.ThefirstwiresendsasupplyvoltagefromtheECM,providingpowerforsensoroperation.Thissupplyvoltageispreciselycontrolledto±0.5volts.ThesecondwireisagroundwirefromtheECMthatsuppliesazerovoltreference.ThethirdwireisthesignalvoltagetotheECM.Thissignalvoltagereflectschangesinthetemperatureofthesystemitismonitoring.Theoperatingrangeofthevoltageisslightlygreaterthanzerovoltstoslightlylessthan5volts.Atypicaloperatingvoltageis0.5to4.5volts.TheECMalsodeterminesifthesignalwireisshortedoropenbymonitoringthesignalvoltage.Ifthesignalvoltageisthesameassupplyvoltage,theECMknowsthesensororsensorcircuitisopen.Ifthesignalvoltageiszero,theECMknowsthesensororsensorcircuitisshorted.IftheECMsensesthecircuitisopenorshorted,itwillindicateafaultforthatcircuittoassistintrouble-shooting.Thekeytemperaturesensorsontheenginearethecoolanttemperaturesensorandtheintakemanifoldairtemperaturesensor.21PressuresensorscontinuouslymonitorsystempressureandsendinformationtoECMHeavymetalbodyfortrouble-freeserviceStraightthreado-ringmountforaleak-freeenginePressureSensors—OilandAir22PressureSensors—OilandAirEnginesystempressuresarecriticaltoperformance,economy,enginelife,andtheenvironment.Oilpressureisthemostcriticalsystempressure.TheoilpressuresensorislocatedinthemainoilgalleyandsendsacontinuousstreamofanalogdatatotheECM.Thecorrectturbochargerboostpressureisessentialtoengineperformance.Boostpressureismeasuredattheoutletoftheturbochargerandintheintakemanifold.TheECMmonitorsboostandambientpressuresandthendeliversthecorrectamountoffuelattheexacttimerequiredtoachieveoptimumpowerandfueleconomywithminimalemissions.23Activeelectroniccircuitryforastrong,dependablesignalPressureSensorComponents24PressureSensorComponentsPressuresensorsmeasurechangesinpressureandsendavariableDCvoltagebacktotheECM.Pressuresensorshavethreewires.ThefirstwiresendsasupplyvoltagefromtheECM,providingpowerforsensoroperation.Thissupplyvoltageispreciselycontrolledto

0.5volts.ThesecondwireisagroundwirefromtheECMthatsuppliesazerovoltreference.ThethirdwireisthesignalvoltagetotheECM.Thissignalvoltagereflectschangesinthepressureofthesystemitismonitoring.Theoperatingrangeofthevoltageisslightlygreaterthanzerovoltstoslightlylessthan5volts.Atypicaloperatingvoltageis0.5to4.5volts.TheECMalsodeterminesifthesignalwireisshortedoropenbymonitoringthesignalvoltage.Ifthesignalvoltageisthesameassupplyvoltage,theECMknowsthesensororsensorcircuitisopen.Ifthesignalvoltageiszero,theECMknowsthesensororsensorcircuitisshorted.IftheECMsensesthecircuitisopenorshorted,itwillindicateafaultforthatcircuittoassistintrouble-shooting.Thekeypressuresensorsontheenginearetheengineoilpressuresensor,theinjectionactuationpressuresensor,theboostpressuresensor,andtheatmosphericpressuresensor.25PressuresensorsprovidecontinuousinformationtoECMPressureinformationisusedbytheECMtoadjustthefuelrateandprotecttheenginePressureSensorCircuit26PressureSensorCircuitTheboostpressuresensormeasurespressureintheintakemanifoldandsendsaDCsignaltotheECM.TheECMusesthisinformationtopreventoverfueling,whicheliminatesblacksmoke.TheatmosphericpressuresensorsendsaDCsignaltotheECM.TheECMutilizesthisinformationtodeterminethealtitudeatwhichtheengineisoperating.TheECMthenadjustsfueldeliveryandtimingtocompensateforaltitudeandmaintainengineperformanceandemissions.Thissensorisnotusedonsomelowerhpratedengines.TheoilpressuresensorsendsaDCsignaltotheECM.TheECMutilizesthisinformationtodeterminetheengineoilpressure.TheECMusesthisinformationtoprotecttheengine.TheECMwillwarntheoperatoroflowpressureandthen,ifconfigured,willshutdowntheengine.27ContinuouslymonitorscoolantlevelandsendsinformationtotheECMHeavymetalbodyfordurabilityStraightthreado-ringmountforleak-freeengineCoolantLevelSensor28CoolantLevelSensorThecoolantlevelsensorismountedbelowthefulllevelmarkintheradiatortopexpansiontank.ItmonitorstheexistenceofthecoolantinthetankandsendsasignaltotheECMindicatingthatcoolantispresentatthatlevel.Ifthecoolantfallsbelowthelevelofthesensor,asignalindicatingalowcoolantlevelissenttotheECM.ThecoolantlevelsensorisusuallyinstalledbytheOEM.29Activeelectroniccircuitryforstrong,accuratesignalCoolantLevelSensorCircuit30CoolantLevelSensorCircuitOnenginesinstalledinover-the-roadvehicles,thecoolantlevelsensorisanOEMinstalledcomponent.Thisistheonlyoptionalsensoronover-the-roadengines.Thissensordetectsthepresenceorabsenceofcoolant.Thesensorhasfourcircuitwires.Thesignalwiresreversethevoltageswiththeabsenceofcoolant.Thefirstwireisthe+5VDCsupply.Thesecondwireisthecoolantlevelnormalsignalwire.Whenthecoolantlevelisnormal,thiswire(coolantlevelnormal)sendsa+5VDCsignaltotheECM.Thethirdwireisthereturn.Thefourthwireisthecoolantlevellowsignalwire.Whenthecoolantleveldropsbelowthetipofthesensor,thiswiresendsa0VDCsignaltotheECM.31SamesensorusedformanyapplicationsmakingOEMinstallationandserviceeasyActiveelectroniccircuitryforstrong,accuratesignalThrottlePositionSensor32Activeelectroniccircuitryforstrong,accuratesignalPWMsignalprovidesreliablesignalstoECMPositionSensorPWMSignal33PositionSensorPWMSignalThethrottlepositionsensormonitorsthepositionofthethrottle(pedalorlever)andconvertsthatpositionintoaPWMsignalwhichitsendstotheECM.Thepositionsensorhasthreewires.ThefirstwireprovidesvoltagefromtheECMtoprovidepowerforoperation.Thissupplyvoltageispreciselycontrolledto8

0.5volts.ThesecondwireisagroundwirefromtheECMthatsuppliesazerovoltsreferencevoltage.ThethirdwireisthesignalvoltagetotheECM.34PositionSensorPWMSignalThepositionsensorgeneratesaPWMsignalwhichisasquarewave.Asquarewavesignaliseitherfullvoltageornovoltage

onoroff.Thepercentoftimethesignalisonversusthetimeoffiscalledthedutycycle.Dutycycleatlowidlepedalpositionis10%to22%.Dutycycleathighidlepedalpositionis75%to90%.ThepedalpositionsensortransmitsthesignaltotheECMataconstantfrequency.ThistypeofsensorprovidesaveryaccuratesignaltotheECMwithasmoothtransitionbetweenaccelerationanddeceleration.TheECMdeterminesifthesensorisfaultybymonitoringthedutycycle.Ifthedutycycleisgreaterthan90%orlessthan10%,theECMwillloganactivefault.35PositionsensorsprovidecontinuousinformationtoECMtomaintainaccuratethrottlepositionThrottlePositionSensorCircuit36ThrottlePositionSensorCircuitTheaccelerationpedalcircuitdeterminesdesiredenginespeedbysensingthepositionoftheacceleratorpedalandsendingaPWMsignalbacktotheECM.TheECMthencomparesdesiredenginespeedtoactualenginespeedanddeterminesthequantityoffueldeliveredbytheinjectors.Theoperatorselectsadesiredenginespeedwiththeacceleratorpedal.ThepositionofthepedalisconvertedintoaPWMsignalandsenttotheECM.ThedutycycleofthesignalistranslatedintoadesiredenginespeedbytheECM.TheECMthencomparesdesiredandactualspeedanddeterminesiftheinjectorsshoulddelivermoreorlessfueltothecylinders.Ifactualenginespeedislowerthandesired,theECMwillincreasecurrenttotheinjectorstoincreasethedeliveryoffuel.Ifactualenginespeedishigher,theECMdoestheopposite.37Outputdevicesonthe3406E,C-10,C-12,and3196aretheinjectorsInadditiontotheinjectors,the3126B,3408E,and3412EhaveaninjectionactuationpressurevalveECMOutputDevices38EUIinjectorshavebeeninservicesincethemid-eightiesHeavyforgedinjectorbodyhandleshighinjectionpressureLargesolenoidandprecisionvalveprovidesexcellentreliabilityCaterpillarElectronicUnitInjector—EUI39HighinjectionpressureatlowrpmforexcellentloadstartingandluggingcapabilitiesHEUIissimpleandrequiresnoadjustmentsforserviceabilityandreliabilityHeavyforgedbodyhandleshighinjectionpressureCaterpillarHydraulicElectronicUnitInjector—HEUI40TheIAPCVcontrolstheHEUIoilpressureThevalveisanintegralpartoftheHEUIhydraulicpumpandisexternallymountedforeasyserviceLargeexternallymountedelectricalsolenoidforefficiencyandserviceabilityInjectionActuationPressureControlValve(IAPCV)41ACaterpillardesignedsystemwithonlyonemovingpartforsimplicityInjectionActuationPressureControlValve(IAPCV)42InjectionActuationPressureControlValve(IAPCV)AsignificantperformancebenefitoftheHEUIsystemisthatitcanproduceanydesiredinjectionpressureatanyenginespeedoroperatingcondition.Thisisplishedbycontrollingtheinjectionoilactuationpressurethatpowerstheinjectors.TheHEUIoilpumppressurizesenginelubricatingoiltopowertheHEUIinjectors.TheIAPCVislocatedinthepumpandcontrolstheoilpressurebyventingsomeoftheoilflowbacktotheoilpan.TheIAPCVisanelectricallyactivatedreliefvalve,whichoperatesbyreceivingavariablecurrentfromtheECM.Alowcurrentwillproducelowoilpressureandahighcurrentproduceshighoilpressure.43ThevalvereceivescurrentfromtheECMtocontrolthehydraulicpressureintheHEUIsystemInjectionActuationPressureCircuit44InjectionActuationPressureCircuitTheinjectionactuationpressurecircuitcontrolstheoperationoftheIAPCV.TheECMdeterminesdesiredenginespeedbasedoninputfromthethrottlepedalandotherenginesensors.TheECMthenusessoftwaremapsprogrammedintothepersonalitymoduletodeterminetherequiredactuationpressuretoproducethedesiredenginespeed.TheECMthencalculatestherequiredcontrolcurrenttosendtotheIAPCVtoproducethedesiredactuationpressure.TheIAPCVrespondstothecontrolcurrentandregulatesactuationpressure.TheECMcontinuallymonitorsactuationpressureandadjuststhecontrolcurrenttoregulatetheactuationoilpressure.45ThetoughvinylcoatednylonwebbingovertheharnessresistsabrasionsandcreatesasecureharnessWiringHarness46ACaterpillarstandardcolorandidentificationforeachwireWiresareColorCodedandNumbered47ConnectorcoversprovideextraprotectionforcriticalapplicationsHarnessConnectorCovers—MarineandIndustrial48Heavy-dutyAMPandDeutschconnectorsConnectorshavelargepinsandsocketsforreliabilityDurableHarnessConnectors49Provideoperator/driverwithimmediateinformationAnoperatorconvenienceaswellasanengineprotectionfeatureWarningLamps50WarningLampsThecheckenginelampisoftenreferredtoasthediagnosticlamp.Thecheckenginelampisusedtoindicatethepresenceofanactivediagnosticcodeandalertthedriverthattheidleshutdowntimerhasstarted.Itisalsousedtoflashdiagnosticcodes.Thewarninglampisanoptionalfeature.Itoperatesinconjunctionwiththeenginemonitoringsystem.Thelampwillturnonwhenthecustomerparameterforenginemonitoringissettowarning,derate,orshutdown.The

maintenanceindicatorlampisusedtoinformtheoperatorthatamaintenanceinterval(PM1,PM2,orCoolantFlush/Fill)isdue.51ECMactivatesavalvetoshutoffintakeairtostopengineQuickandpositivestoppingofengineinemergencyEmergencyStopControl52ECMcontrolsquantityandtimeofetherinjectionaccordingtotemperatureandenginerpmSystemprovidessafeuseofetherandisagreatoperatorconvenienceEtherInjectionStation53EtherInjectionStationTheetherinjectionsystemisoptionalonindustrialandmarineengines.TheECMusestemperatureinformationfromtheenginecoolanttemperaturesensorandenginespeedinformationtodetermineifetherisneededandtheamounttoinject.Ifthetemperatureisbetween-40

Cand10

C(-40

Fand50

F)andtheengineiscrankingover30rpm,ethercanbeinjected.Theinjectiontimeisdeterminedbytemperatureandwillbebetween15and130seconds.54ECMVariablesSystemconfigurationparameters—setatthefactoryCustomerprogrammableparameters—modifiedbythecustomertofine-tunetheengine55ECMMonitorsEngineandItselfECMcontinuallymonitorsallenginesystemsanditsowncircuitryIssuesactivecodestowarntheoperatorofanimmediateproblemKeepstrackofoldproblemswithaloggedcodefunction56ECMMonitorsEngineandItselfInadditiontomonitoringalloftheenginesystems,theECMcontinuallymonitorsitself.Whenaproblemisdetected,theECMgeneratesanactive

fault

codeandturnsonthediagnostic/checkenginelamp.Eachcodehasauniquenumberandisstoredinmemory.Codesthatarenolongeractivearecalledloggedcodes.Aloggedcodeindicatesthataproblemhasoccurred,butisnotpresentlyactive.57LifetimeTotalsStoredbytheECMLifetimetotalsprovideacompleteoperatinghistoryoftheengine58TripDataStoredintheECMECMstorestripdataforoperatorandmanagementuse59FleetHistogramsEasy-to-understandgraphicalinformation60ColdModeAutomaticallylimitspoweratstartupuntiltheenginereachesoperatingtemperature61FuelTemperaturePowerCompensationECMadjustspoweroutputtocompensateforinconsistenciescausedbyfueltemperaturevariations62FuelTemperaturePowerCompensationThefueltemperaturesensorcontinuallymonitorsthetemperatureoftheenginefuel.TheECMusesthisinformationtoadjustthefuelratecalculation(fuelinjectionrate)andforfueltemperaturepowercorrection.TheECMperformsafueltemperaturepowercorrectionwhenthefueltemperatureexceeds30

C(86

F)tomaintainaconsistentpowerlevel.Maximumpowercorrectionisachievedat70

C(158

F).Fueltemperaturesexceeding80

C(176

F)for30secondscauseadiagnosticcodetobelogged.63EngineMonitoringSystemEMSisaprogrammablemonitoringsystemdesignedtooperatewithCaterpillarengines64EngineMonitoringSystemTheECMprovidesaccesstoenormousamountsofreal-timedata.TheCaterpillarEMSisanexcellentandconvenientmethodforviewingthisenginedata.WithEMS,youcanviewimportantengine,transmission,andrelatedsystemparameters.EMSprovidesexcellentvisibilityinalllightingsituations.ItisprogrammedtodisplayU.S.customaryunitsormetricunits.65TeniconwarninglampsTheLCDdisplaysdifferentengineandtransmissionparametersMainUnit66FouranaloggaugeswithreddangerzonesUnithasanalarmoutputMonitorsselectedsystemsQuad-GaugeUnit67LargeanaloggaugeDigitalLCDforotherdataTachometerUnit68Allowsthecustomertofine-tuneengineperformancetoaspecificapplicationCustomerSpecifiedProgrammableParameters69CustomerSpecifiedProgrammableParametersCaterpillarspecifiedprogrammableparametersallowtheengineowner/customertoselectfeatures,operatingparameters,andpowerratings(withinspecifiedfamilies)topreciselymatchthevehicletotheapplication.Thesefeaturescanprovideoperatorconveniences,enhancefuelefficiency,andeveninfluencehowavehicleisdriven.ThesefeaturesareaccessedthroughtheCaterpillarservicetools(ECAPandET).70EnginemonitoringsystemcanbeprogrammedtoprovideseveraldifferentlevelsofprotectionEngineMonitoringSystem71EngineMonitoringSystemEachenginesubsystemismonitoredbyoneormoresensors,whichprovidecontinuousinformationtotheECMaboutoperatingconditions.TheECMutilizesthisinformationtocontrolengineoperationandalerttheoperatortoapotentialproblem.Thismonitoringsystemcanbeprogrammedtoprovidefourdifferentlevelsofprotection:OEMscanprogramthemonitoringsystemtobettermatchexistingvehiclesystems.OFF-nomonitoringWarning-alertsdrivertotakeactiontoavoidenginedamageWarning/Derate-alertsdriverandderatesengineWarning/Derate/Shutdown-automaticallyshutstheenginedownifoneofthemonitoredconditionsexceedsapredeterminedsetting72TwomodesprovidestandardandenhancedoperationforoperatorconveniencePTOMode73AllowsthePTOrampspeedtobepreciselymatchedtoacriticalapplicationPTORampRate74AllowsthetorquetobematchedtoaspecificPTOfunctionorapplicationPreventsexcesstorquefrompotentiallydamagingasensitiveapplicationTorqueLimit75LowEngineIdleAllowsidlespeedtobesetbetween600and750tomatchvehiclerequirements76AllowsthehighidletobematchedtoaspecificapplicationProvidesasafeupperrpmlimitHighEngineIdle77AllowsaprogrammedintermediaterpmforauniquePTOorengineapplicationIntermediateEngineSpeed78ProvidesamaximumrpmwhentheengineisunderloadTopEngineLimit(TEL)79AllowsothervitalsystemstobemonitoredbytheECMAuxiliaryPressureandTemperature80ECMcalculatesmaintenanceintervalsandinformstheoperatorofnecessarymaintenanceMaintenanceIndicatorModeWhenthisfunctionisactivated,theECMtracksandrecordsdatarelatedtounitmaintenance.Whentheunitreachesamaintenanceinterval(PM1,PM2,orCoolantFlush/Fill),theECMwillturnonthemaintenancelamp.81824BasicFunctionsofEUIInjectorsPressurizesupplyfuelinjectionpressureAtomizethehighpressurefuelbypumpingitthroughorificesintheinjectortipDeliverthecorrectquantityofatomizedfuelintothecombustionchamberDispersetheatomizedfuelevenlythroughoutthecombustionchamber83InjectorComponents84EUIvs.EarlierInjectorsTheEUIinjectorismechanicallyactuatedmuchlikeearlierCaterpillarunitinjectors.Themajordifferenceisintheinjectorcontrolsystem.TheEUIiselectronicallycontrolledbytheengineECM.85SolenoidThesolenoidandpoppetvalveareanintegralunitandmountonthesideoftheinjectorbody.Thesolenoidassemblycontainsthesolenoidcoil,armature,andpoppetvalve.Thearmatureandpoppetvalveareattachedandfunctionasaunit.Thesolenoidisanelectromagnetwhichcreatesaverystrongmagneticfieldthatattractsthearmature.Asthearmaturemovestowardthesolenoid,thevalveseatsandshutsofftheflowoffueltostarttheinjectionprocess.86PoppetValveOpenPositionWhenthesolenoidisnotenergized,thevalveisintheopenposition.Thisisthenormalpositionforthevalve.ClosedPositionWhenthesolenoidisenergized,thearmatureliftsthepoppetandseatsittostoptheflowoffuelthroughthevalve.87InjectorBodyTheinjectorbodycontainsthebarrelandplunger,fueldrillings,andthemountforthesolenoid.Theplungerandbarreltogetheractasapump,muchlikeamedicalsyringe.Boththeplungerandbarrelareprecisioncomponentswithverysmallworkingclearances.Thesetightclearancesarerequiredtoproduceinjectionpressuresabove20,000psi.88NozzleAssemblyComponents89NozzleAssemblyThenozzleassemblyissimilartootherCaterpillarunitinjectors.Fuelatinjectionpressureflowsfromtheplungercavitythroughapassagetothenozzletip.Fuelflowoutofthetipisstoppedbythenozzlecheck,whichcoverstheorificesintheendofthetip.Thetipisheldintheclosedpositionbytheforceofthenozzlespring.90ValveOpeningPressureWheninjectionpressureincreasestoapproximately5,500psi,hydraulicforceactingonthenozzlecheckesthespringforceandliftsthecheckoffitsseat.ThepressureatwhichthecheckopensiscalledValveOpeningPressure(VOP).91ValveClosingPressureThecheckremainsopenandfuelisinjectedintothecombustionchamberuntilinjectionpressuredropsbelow5,500psi.Whenpressuredrops,thecheckclosesandinjectionisstopped.ThepressureatwhichthecheckclosesiscalledValveClosingPressure(VCP).924StagesofEUIInjectionPre-injectionInjectionEndofInjectionFuelfill93Pre-InjectionWithnopressureappliedtotheplungerfromthecamshaft,theinjectorreturnspringkeepstheplungerretracted.Fuelflowsatapproximately60psifromthetransferpumpthroughtheinjectortokeepitfilledwithfuelandcooled.94StartofInjectionAsthecamshaftlobecontactstherollerfollower,theplungerwillstartitsdownwardtravel.Sincethesolenoidvalvehasnotbeenactivatedyet,thefuelinthebarrelwillflowthroughthesolenoidvalveandoutofthefill/spillport.95InjectionWhentheECMdeterminesthattheinjectorshouldfire,itsendsacurrenttotheinjectorsolenoidtoclosethepoppetvalve.Thisblockstheflowoffueloutoftheinjectorandtrapsthefuelwithintheinjector.Pressureelevatesquicklyastheplungercontinuesitsdownwardtravel.Whenthefuelreachesvalveopeningpressure,approximately5,500psi,thenozzlecheckvalveliftsoffitsseatandinjectionbegins.96InjectionAsthecamshaftcontinuestorotate,theplungerwillcontinueitsdownwardtravel.Fuelwillnowbeinjectedintothecombustionchamber.Thesprayholesinthenozzleareverysmallandwillresisttheflowoffuelintothecombustionchamber.Thefuelpressurewillcontinuetorisetonear20,000psiasinjectioncontinues.Thehighfuelpressure,alongwiththesmallsizeandangleoftheholesinthenozzlewillcontroltheatomizationofthefuelintothecombustionchamber.Fuelwillcontinuetobeinjecteduntilthesolenoidisde-activated.97EndofInjectionTheendoftheinjectioncyclebeginswhentheECMshutsoffthecurrenttotheinjectorsolenoid.Asthemagneticfieldofthesolenoidcollapses,thepoppetvalveun-seats.Thisallowsthehighpressurefuelinthebarreltoescapetothefill/spillport.WhentheinjectionpressuredropsbelowValveClosingPressure,thenozzlecheckcloses,endinginjection.98FuelFillSincetheplungerisactivatedbythecamshaft,itwillcontinuetothebottomofitsstrokeinthebarrel.Fuelinthebarrelwillbeforcedoutthefill/spillportasitwasbeforeinjectionstarted.Atthebottomofitsstroke,theplungerreturnspringwillforcetheplungerupinthebarrel.Thefuelpressurefromthetransferpumpwillfillthebarrel.Theinjectorisnowreadyforthenextcycle.991004BasicFunctionsofHEUIInjectorsPressurizesupplyfuelfrom65psito5,400-23,500psiAtomizetheh