《汽车专业英语》-Chapter Two Engine Control Technology

2.1TheElectronicIgnition2.1.1Electronic-Ignition-SystemComponentsAnelectronicignitionsystemhasbasicallythesamecomponentsasthecontact-pointsystem（Fig2-1）.Bothincludethebatteryoralternator，ignitioncoil，wiring，andsparkplugsHowever，theelectronicignitionsystemincludesanelectroniccontrolunit（ECU），orelectroniccontrolmodule（ECM）.Intheelectronicignitionsystem，thedistributorhasadevicewhichcreatesvoltagepulse.Attherighttime，itsignalstheECUwhichthenopenstheprimarycircuit.Asthecurrentflowstops，themagneticfieldaroundtheignitioncoilcollapses，producingahigh-voltagesurge.Thisisledthroughthewiring，distributorcap，androtortothesparkplugsinthecylinderthatisreadytofire.下一页返回2.1TheElectronicIgnitionMostautomotiveignitionsystems（bothcontact-pointandelectronic）areclassedasinductiveignitionsystemsTheprimaryenergyisstoredasamagneticfieldaroundtheignitioncoilAfterthecurrentflowstops，theactionsinthesecondarycircuitarethesameinboththecontact-pointandelectronicsystemsHowever，severalmethodsareusedinelectronicignitionsystemstoopenandclosetheprimarycircuit上一页下一页返回2.1TheElectronicIgnition2.1.2Electronic-Ignition-SystemOperation

Fig2-2showsatypicalelectronicdistributorwiththecapremovedThepickup-coilassemblyconsistsofapermanentmagnetandacoilthatiswoundaroundametalbarcalledapolepieceItisanextensionofthemountingbracket.Thereluctor（Fig2-2）isagear-likecomponentthatisattachedtothetopofthedistributorshaft.Thisisthesamepositionasthecaminthecontact-pointdistributor.Thereluctorismadeofiron，andhasone“tooth”foreachcylinderintheengineInthedistributor，asmallairgapseparatesthereluctorteethandthepickup-coilassembly，sotheynevertouch上一页下一页返回2.1TheElectronicIgnitionThereluctorisnotamagnetWhenatoothonthereluctorentersamagneticfield，thetoothprovidesabettermagneticpaththanthesurroundingairThisreducesreluctance，whichistheresistanceofamagneticpathtotheflowofmagneticlinesofforceThepermanentmagnetinthepickup-coilassemblyproducesaweakmagneticfieldItpassesthroughthepickup-coilwindingwhichiswrappedaroundthepolepiece［Fig2-3（a）］.Thismagnetfieldisrelativelyweakwhenthereisawideairgapbetweenthepolepieceandtheteethonthereluctor上一页下一页返回2.1TheElectronicIgnition2.1.3Pickup-VoltageSignals

Thevoltageisinducedinthepickup-coilbythechanging（increasingordecreasing）fieldstrength.Novoltageappearsunlessthereluctorismoving.Therapidincreaseanddecreaseofthemagneticfieldastherotatingreluctorteethapproachandpassthepolepieceproducesapositive，thenanegativevoltageatthepickup-coilterminalsThesevoltagesactasswitchingsignalsTheycausetheECUtoallow，andthenpreventcurrentflowingthroughtheprimarywindingoftheignitioncoil上一页下一页返回2.1TheElectronicIgnitionThevoltageinducedinthepickupcoiliscalledthepickupvoltageItisaverysmall，preciselytimedelectricalsignalthatisfedtotheECU.TheECUcanallowcurrentflowthroughtheprimarywindingoftheignitioncoilaslongasthepickup-voltagesignalisapositivevoltage.Inallelectronicignitionsystems，thebatterycurrentflowsthroughtheprimarywindingoftheignitioncoilandthroughtheECUtoground.TheECUremainson（primarywindinggrounded）untilanegativevoltagepulseisreceivedfromthepickupcoil上一页下一页返回2.1TheElectronicIgnitionAssoonasthepickup-voltagesignalisanegativevoltage，theECUopens（alsocalledturnsoff，deactivates，orinterrupts）theprimarycircuit（Fig2-4）.Now，nocurrentcanflowthroughtheECUtogroundAsaresult，themagneticfieldaroundtheignitioncoilcollapsesThisinducesahighvoltageintheignition-coilsecondarywinding，whichfiresthesparkplugTheseactionsarethesameasinthesecondarycircuitofthecontact-pointignitionsystem上一页下一页返回2.1TheElectronicIgnition2.1.4DwellandTimingintheElectronicIgnitionIntheelectronicignitionsystemdescribedabove，theECUdetermineshowlongtheprimarycurrentflowsbeforeitisinterrupted.ThisissimilartodwellinthecontactpointignitionsystemSincetheECUissealedandhasnomovingparts，dwellcannotbechanged.TheECUandthepickup-coilassemblyandreluctoracttogethertodeterminehowlongcurrentflowsintheprimarycircuit（dwell）andwhentointerruptit上一页下一页返回2.1TheElectronicIgnitionInelectronicignitionsystems，anincreaseinenginespeedmaycausethedwelltoincrease，todecrease，ortoremainconstantThechangeindwell（ifany），andtheallowabledwellvariation，dependsonthedesigncharacteristicsofeachelectronicignitionsystemHowever，dwellincreasewithenginespeedincreaseisacharacteristicoftheGeneralMotorsHEIsystem.Ignitiontimingiscontrolledbytheinitial-advancesettingofthedistributor（basictiming）andbydistributormountedcentrifugalandvacuumadvancemechanismsTheycontroltherelationshipbetweenthepositionofthereluctortoothandthepositionofthecrankshaftandpiston上一页下一页返回2.1TheElectronicIgnition2.1.5Hall-EffectDistributorsSomecarshaveanelectronicdistributorinwhichthemagnetic-pickupcoilisreplacedbyasensorthatusestheHalleffect（Fig2-5）.Whenathinsliceofsemiconductormaterialcarryinganelectriccurrentiscrossedatrightanglesbyamagneticfield，avoltageappearsattheedgesoftheconductor.ThisvoltageiscalledtheHallvoltage

上一页下一页返回2.1TheElectronicIgnitionKeyWordsandExpressionsPickupcoil—thecoilinwhichvoltageisinducedinanelectronicignition拾波线圈Reluctance—theresistancetomagneticfluxinamagneticcircuit；analogoustoresistanceinanelectricalcircuit磁阻Reluctor—aHallgeneratorrotorwithanouterringinterruptedbyoneorseveralHallwindows，dependingonitspurpose磁阻转子Shutter—acurvedmetalvaneorabladeofaHallgenerator导磁部分上一页下一页返回2.1TheElectronicIgnitionHall-effect—inelectricalconductorswhereelectriccurrentflowsperpendiculartoamagneticfield，aso-calledHallvoltageisproducedperpendiculartothedirectionofcurrentflowandtothemagneticfield霍尔效应

Dwell—inacontactbreakerignitionsystem，thenumberofdegreesthebreakercamrotatesfromthetimethebreakerpointscloseuntiltheyopenagainAlsocalledthe“dwellangle”or“dwellperiod”Inabreakerlessignitionsystem，thetimeduringwhichtheelectroniccontrolunitallowscurrenttoflowthroughtheprimarywindingofthecoil，whichinignitionsystemswithaHallgeneratorisdeterminedbythewidthofthevanes触点闭合时间上一页返回2.2TheElectronicFuelInjection2.2.1TypesoftheGasolineFuelInjectionInthegasolinefuel-injectionsystem，thefuelissprayedintotheairbysolenoid-operatedinjectionvalveTherearetwobasicarrangements:theportinjection（Fig2-7）andthethrottle-bodyinjection（TBI）.Theportinjectionisknownasmultipointinjection.Thefuelisinjectedatseveraldifferentplaces，whilethethrottle-bodyinjectionisinjectedinoneplaceAtproperinstant，theinjectionvalvesprayfuelintothevalveport（Fig2-8）.Whentheintakevalveopens,theair-fuelmixtureflowsintothecylinderEachinjectionvalveopensinthesamesequenceastheenginefiringorder.However，allportinjectionsystemsarenotsequentialinoperation.Insomesystems，theinjectionvalvesopeningroups

下一页返回2.2TheElectronicFuelInjectionThethrottle-bodyfuelinjectionisshowninFig2-9.Theinjectionvalvessprayfuelintoairbeforeitpassesthethrottlevalvesonitswaytotheenginecylinders上一页下一页返回2.2TheElectronicFuelInjection2.2.2TheElectronicFuelInjection（EFI）

TheEFIsystemincludesanECUandavarietyofsensorsThesensorsreporttotheECUonvariousconditionssuchasenginespeed，coolanttemperature，manifoldvacuum，throttlepositionandsoonTheECUanalyzesthisinformationThenitsignalstheinjectionvalvestodeliverproperamountofmixtureofthedesiredair-fuelratio上一页下一页返回2.2TheElectronicFuelInjection2.2.3CadillacElectronicPortInjectionThereisaseparateinjectionvalveforeachcylinderinCadillacelectronicportinjectionsystemTheyareallconnectedtoafuelrail.TheinjectionvalvesaredividedintotwogroupsoffourvalveseachEachgroupofinjectionvalvesisturnedonalternatelybytheECU.

上一页下一页返回2.2TheElectronicFuelInjectionTheECUisapreprogrammedcomputerthatconvertstheinputinformationfromthesensorsintoelectricpulsesThelengthofthepulseopenstheinjectionvalvesfortheproperdurationatthepropertimeInthissystem，thedurationofthepulsedetermineshowmuchfuelaninjectionvalvewillinjectForhigh-speedfullpower，thedurationwillbelongersothatmorefuelwillbeinjected.上一页下一页返回2.2TheElectronicFuelInjection2.2.4GMThrottle-BodyInjection（TBI）SystemATBIsystemusedbyGeneralMotorsisshowninFig2-16Theelectroniccontrolmodule（ECM）analyzesvoltagesignalsfromseveralsensorstodeterminehowmuchfueltheengineneedsFortheGeneralMotorsTBIUnitasshowninFig2-17，itincludes：(1)TheThrottleBody(2)TheFuelBody(3)TheInjectionValve(4)ThePressureRegulator(5)TheIdleAirControl（IAC）Valve上一页下一页返回2.2TheElectronicFuelInjectionKeyWordsandExpressionsPortinjection—atypeoffuelinjectionwithatleastoneinjectormountedintheintakeport（s）ofeachcylinder.Usuallytheinjectorismountedontheairintakemanifoldclosetotheport进气道喷射系统

Throttle-bodyinjection（TBI）—aformoffuelinjectioninwhichtheinjectorsarelocatedattheengine‘sthrottlebodytherebyfeedingfueltomorethanonecylinder进气管喷射系

Multipointinjection—agasolinefuel-injectionsysteminwhichonlyairenterstheinletmanifold；astheairapproachestheinletvalve，aninjectionvalveopensinthevalveport，sprayingfuelintotheairstream多点喷射上一页下一页返回2.2TheElectronicFuelInjectionBackfire—apassageofunburnedfuelmixtureintotheexhaustsystemwhereitisignitedandcausesanexplosion（backfire）prematurely回火

Pressureregulator—aspring-loadeddiaphragmtypepressure-reliefvalvewhichgovernsthepressureofthefueldeliveredtothefuelinjectorsbythefuelpumpandreturningtheexcesstothetank压力调节器

Stall—anenginewhichstopsunintentionally.Theusualcausesofstallingare：suddenincreaseinloadwithoutanaccompanyingincreaseinfuelflowandbrakingtoaverylowspeedwithoutdisengagingtheclutch（发动机）熄火上一页返回2.3TheCommonRail2.3.1AreasofApplicationThecommon-railfuel-injectionsystemforengineswithdieseldirectinjection（DirectInjection，DI）isusedinthefollowingvehicles：①Passengercarsrangingfromhigh-economy3-cylinderengineswithdisplacementsof800cc，poweroutputsof30kW（41HP），torquesof100N·m，andafuelconsumptionof3.5L/100kmthroughto8-cylinderenginesinluxury-performancesedanswithdisplacementsofapprox4.0L，poweroutputsof180kW（245HP），andtorquesof560N·m下一页返回2.3TheCommonRail②Light-dutytruckswithenginesproducingupto30kW/cylinder，andheavy-dutytrucks，railwaylocomotives，andshipswithenginesproducinguptoapprox200kW/cylinderThecommon-railsystemisahighlyflexiblesystemforadaptingfuelinjectiontotheengine

上一页下一页返回2.3TheCommonRail2.3.2PrinciplesoftheCommonRailThecommon-railsystemconsistsofthefollowingmaincomponentgroups（Fig2-19）：

①Thelow-pressurestage，comprisingthefuel-supplysystemcomponents;②Thehigh-pressuresystem，comprisingcomponentssuchasthehigh-pressurepump，fuelrail，injectors，andhigh-pressurefuellines上一页下一页返回2.3TheCommonRailTheelectronicdieselcontrol（EDC），consistingofsystemmodules，suchassensors，theelectroniccontrolunit，andactuators.Thekeycomponentsofthecommon-railsystemaretheinjectors.Theyarefittedwitharapid-actionvalve（solenoidvalveorpiezo-triggeredactuator）whichopensandclosesthenozzle.Thispermitscontroloftheinjectionprocessforeachcylinder上一页下一页返回2.3TheCommonRailAlltheinjectorsarefedbyacommonfuelrail，thisbeingtheoriginoftheterm“commonrail”Inthecommon-railfuel-injectionsystem，thefunctionsofpressuregenerationandfuelinjectionareseparate.Theinjectionpressureisgeneratedindependentoftheenginespeedandtheinjectedfuelquantity.Theelectronicdieselcontrol（EDC）controlseachofthecomponents.(1）PressureGeneration(2）PressureControl(3）FuelInjection(4）PotentialHydraulicPower(5）ControlandRegulation(6）ControlUnitConfiguration上一页下一页返回2.3TheCommonRailKeyWordsandExpressionsNozzle—aprojectingpartwithanopening，asattheendofahose，forregulatinganddirectingaflowoffluid喷嘴Secondaryinjection—thesecondstageofthefuelinjection二次喷Specificpower—theaverageoutputpowerperkilograms比功率Turbocharger—inductionpressurechargernormallycomprisinganexhaustgasdrivenairturbinedrivinganaircompressor涡轮增压器Boost-pressure—pressureintheintakesystemofasuperchargedenginewhenthesuperchargeroperates增压压力上一页下一页返回2.3TheCommonRailCruisecontrol—afeaturethatkeepsyourvehiclemovingatasetspeed巡航控制Immobilizer—adevicethatpreventsfrombeingstolen发动机防盗系统上一页返回2.4TheExhaustGasRecirculation2.4.1PrinciplesofEGRSystemsEGRisatechniqueforreducingNOxgasesespeciallyinDieselengines.Portionsofoxygen-meagreexhaustgasesarecooledandrecirculatedintotheengineandmixedwithoxygen-richintakeair（showninFig2-22）.Duetothefeweramountofoxygenmoleculesinthecombustionair,thepeakcombustiontemperatureandtheamountofexcessoxygenarereduced,whichresultsinlessNOxformation

下一页返回2.4TheExhaustGasRecirculationGenerallyspeaking，EGRflowshouldmatchthefollowingoperatingconditions：①HighEGRflowisnecessaryduringcruisingandmid-rangeacceleration，whencombustiontemperaturesaretypicallyveryhigh；②LowEGRflowisneededduringlowspeedandlightloadconditions；③NoEGRflowshouldoccurduringconditionswhenEGRoperationcouldadverselyaffectengineoperatingefficiencyorvehicledriveability(enginewarmup，idle，wideopenthrottle，etc).上一页下一页返回2.4TheExhaustGasRecirculation2.4.2ClassificationofEGRSystemsVariousEGRsystemshavebeenclassifiedonthebasisofEGRtemperature，configurationandpressure(1）ClassificationBasedonTemperature①HotEGR：Exhaustgasisrecirculatedwithoutbeingcooled，resultinginincreasedintakechargetemperature②FullycooledEGR：Exhaustgasisfullycooledbeforemixingwithfreshintakeairusingawater-cooledheatexchanger.Inthiscase，themoisturepresentintheexhaustgasmaycondenseandtheresultingwaterdropletsmaycauseundesirableeffectsinsidetheenginecylinder上一页下一页返回2.4TheExhaustGasRecirculation③PartlycooledEGR：Toavoidwatercondensation，thetemperatureoftheexhaustgasiskeptjustaboveitsdewpointtemperature(2）ClassificationBasedonConfiguration①Longroutesystem（LR）②Shortroutesystem（SR）③AnotherwayofcontrollingtheEGR

上一页下一页返回2.4TheExhaustGasRecirculation(3）ClassificationBasedonPressureTwodifferentroutesforEGR，namelylow-pressureandhigh-pressureroutesystemsmaybeused①Lowpressureroutesystem②Highpressureroutesystem上一页下一页返回2.4TheExhaustGasRecirculation2.4.3TheElectricDieselEGRValvewithPressureCompensationInthedieselengine，theEGRvalvemustsealsecurelyagainstexhaustbackpressureandchargingairpressurea