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UNIT3FUELINJECTIONSYSTEMSTEXTBFunctionsoftheMotronicSystems,PROFESSIONALENGLISH,UNIT3FUELINJECTIONSYSTEMSTEXTBFunctionsoftheMotronicSystemsIgnitionTimingControlControlUnitDwell-AngleControlIdleSpeedControl,本次课学习内容,本次课学习目标,掌握Motronic系统的主要功能及其作用原理掌握常用术语了解相关术语提高翻译能力,NEWWORDS,coordinatekou:dineitv.调整，整理modelmdln.模型，典型，圆形，车型；v.模拟troubleshoottrblu:tv.排除故障condenserkndensn.冷凝器，电容器patchptv.修补，补缀interpolateint:pouleitv.窜改fall-offf:l-fn.衰退，减少，逐渐下降conservekns:vv.保存，保藏，守恒,dwelltime闭合时间，初级电路接通时间shortof缺乏，缺少，不够（标准）atthemomentof在一刻，当时idle-speedcontrol怠速控制bederivedfrom由得来，来源于allthewhile一直，始终lambdaclosed-loopcontrol闭环控制idle-speedstabilizer怠速稳定器,PHRASESANDEXPRESSIONS,FunctionsoftheMotronicSystemsInsimpleterms,Motronicisanengine-managementsystemwithasinglecontrolunitforcontrolofignitiontimingaswellasfuel-injection.Manyofthesensorsimportantforfuelinjectionarealsoneededforignition-systemcontrol,sotheintegrationofthetwosystemscanaccomplishmanythings:Integratedcontroloffuelinjectionandignitioncanmanagetheenginebetterthancontrolofeitheronealone.Thatis,timingissometimesdependentontheair-fuelratio,andviceversa;also,emissionscanbereducedbycoordinatedcontrol.Enginecontrolcanbebasedonactualneedsofeachenginemodelbasedonlargeamountsofengine-testdataduringdifferentoperatingconditionsstoredintheMotronicReadOnlyMemory(ROM)11根据Motronic系统的只读存储器（ROM）中所存储的大量试验数据，就能够按照每个发动机机型的实际需要，对发动机进行控制。Motronic系统的只读存储器（ROM）中所存储的这些试验数据是在发动机不同工况期间通过试验而得到的。,Manyadditionaloperatingfunctionscanbeprovided.Importantfromthestandpointofservicearetheadaptivefunctions,andtheself-diagnosticsfortroubleshootingMotronicadvantagesarebetterdriveabilityandfuelefficiency,andreducedemissions.Morespecificbenefits:a.fuelsavingsachievedfrombestcombinationofmixtureandtimingb.dependablestarting,coldorhotc.stableidlingatreducedrpme.relativefreedomfrommaintenancef.goodtorquecharacteristics,allowinglongergearratios,IgnitionTimingControlImtalkinghereaboutmorethanelectronicignition-thesystemsthathavereplacedthepointsandcondensersofyesterday.Imtalkingaboutmicrocomputercontrolofignitionadvanceangleforeveryplugfiring,oratmost,everytwoplugfirings.Themillisecondresponsetimeofelectronicignitionadvancecontrolisfarfasterthanthetraditionalmechanicalflyweight/vacuumadvancesystems.Inamechanicalsystem(andthatincludeselectronicignition),asrpmincreases,centrifugalweightsadvancetiming.Changingload(manifoldpressure)canfurtherchangetimingadvancewithavacuumdiaphragm.Asrpmincreases,thereislessdwelltimeforthecoiltochargewhenperhapstheengineneedsmoresparkenergy.Traditionalcurvesfordistributortimingshowthelimitedcontroloftimingadvancepossible.Atimingpointthatisproperforonecombinationofrpmandloadisprobablywrongforothercombinationsofcentrifugalweightpositionandvacuumdiaphragmaction.Oncethevacuumcontrolorthecentrifugalweightsreachtheirlimits,advancecontrolisfixed.,Mechanicaltiminghasbeenpatchedwithmorevacuumhoses,temperatureanddelayvalves,andotherservicingheadaches;itsstillacompromise.Evenatitsbest,thiscontrolfailsfarshortofthepreciseandrapidtimingneededbytodayscars.InMotronicsystems,however,thecontrolunitprocessesanumberofinputs,andthenadjuststimingforallconditionsbasedonitsinternaldatamap.TimingDataMapsTodetermineprecisetiming-advancerequirements,eachfamilyofenginesistestedtolearnthebesttimingforeachconditionofspeed,load,andothervariablesinheatandcold,onthedynamometerandinthemountains.Thegoalistofindthetimingforbestpower,forbesteconomy,allthewhilemeetingemissionlimits.,Fig.3-3Ignitionadvancemapshowselectronictimingcontrolaccordingtoengineloadandspeed.Themapsaresymbolicofthousandsofdatapointsstoredincontrolunitmemory.,Theresultofthesetestsisaseriesofdatamaps,asshowninFig.3-3.LiterallythousandsofdatapointsfromthesetestsarestoredinthecomputermemoryoftheMotroniccontrolunitROM(ReadOnlyMemory)forreadoutduringengineoperation.Asyoumayknow,aROMcannotbechanged.Foranycombinationofengineloadandrpm,thecontrolunitcansupplythebestignitiontiming.Forexample,foranrpm-inputsignalof2000rpm,ataloadsignaledbytheair-flowsensor,thecomputerwouldlookupthetimingadvanceangle,letssayitshouldbe22degreesBTDC.Butcontrolisevenmoreprecise.Supposetherpmwere2050,andthememorycontainedonlydatapointsfor2000and2100;thenthecomputerwouldlookupboth2000=22degreesBTDC,and2100=24degreesBTDC,andinterpolate.Itwouldcalculateanadvanceforthe50rpmdifferencebetween2000and2050,andwouldoutputtimingof23degreesBTDC.Inthecontrolunit,timingiscomputedsofastthatMotroniccanadjusttimingforeveryfiringofeachsparkplug!,DistributorBecauseitdoesnotcontroltimingorsignalrpm,theMotronicdistributorsonlyjobistodistributethesecondary,thatis,tosendthecontrol-unit-timedsparktothepropercylinder.Whiletiminganddwellwereformerlydependentoneachother,Motronicmemoryprovidesseparatedwell-angledata,basedonbatteryvoltageandrpm.Later,wellseehowtiminganddwellcontrolimprovestartingandothervariations,butherearetheprinciples.Dwell-AngleControlAsenginerpmincreasesonmechanicaladvancesystems,thereislessdwelltimeforthecoiltochargebetweenfirings,resultinginafall-offofcoilvoltage.InMotronicsystems,dwellangleiselectronicallycontrolledsothecoilreceivesthepropercurrentatthetimeofplugfiring.Themorebatteryvoltage,thelessdwellangleneeded.Ontheotherhand,asrpmincreases,moredwellangleisneededforthetimetochargethecoil.,Fig.3-4Dwellangleiscontrolledforbatteryvoltageandenginespeed,accordingtomemorymapincontrolunit.,Bycontrollingdwellangle,thecoilischargedproperlyforeachignitionfiring,nomore,noless.Theobjectiveistoprovidetherequiredsecondarypowerattheplugatthemomentoffiringwithminimumlossesintheignitionoutputtransistorandthecoil.,Toreachthenominalvalueofprimarycurrentatthemomentoffiring,thedwellangleischangedaccordingtothebatteryvoltageasshowninFig.3-4.Whenbatteryvoltageisless,dwelltimeisincreased.Ineffect,thedwellcontrolanswersthequestion:Whenshouldtheprimarycircuitbeclosedfortheoptimumtimeforthecoilprimarycurrenttorisetopropervalueatmomentofopeningprimarycircuit?Inaddition,thecontrolunitoutputstagelimitscurrentsothatif,duetorapidenginespeedchangesasinacceleration,currentreachesthenominalvaluebeforetheignitionpoint,currentisheldconstant.Soenginerpmandbatteryvoltageareinputstothecontrolunit.Fromdwell-angledataintheROM,controlunitoutputisthedwell,orcharge-timecontrol,thatconservesenergyandpreventsoverheatingthecoil.Also,iftherpmsignalindicateslessthan30rpm,aswhentheenginestopsorthekeyisleftonwiththeenginestopped,primarycut-offpreventscoiloverheating.NowthatyouunderstandthebasicsofMotronicignitioncontrol.,ControlUnitMotronicsystemsmakeextensiveuseofotherdatamapsstoredinROMformanyofthecontrolunitfunctions,including:fuelinjectionlambdaclosed-loopcontrolwarm-upaccelerationignitiontimingdwellangleEGRidle-speedcontrolLambdamemorymapThemainmapinthecontrolunitisasetoflambdamemory-pointsusedtodeterminethedesiredair-fuelratioforthefuelinjectionpulses.Thelambdamemorymap,showninFig.3-5,isderivedfromlabandroadtests,andmodifiedfortherequirementsofthevehicleandthecountrywhereitwilloperate:,atpartload,maximumeconomyandminimumemissionsatwide-openthrottle,maximumtorquewhileavoidingknockingatidle,maximumsmoothnessduringthrottleopening,maximumdriveabilityAirquantityandtherequirementsforcontrolofinjectedfuelcanvaryduetomanyfactorssuchasmanifold-pressurevariationsresultingfromindividualpistonpumping,andintake-valveopening/closing2.Idlingmanifoldabsolutepressurecanvaryby5kPafromanaverage42,overmorethan10%plusorminus3.Forthisandothervariations,thelambdamapinsuresthebestpossibleadjustmentoftheair-fuelratioascorrectedbyinputsthatcontrolfuelinjection,andwithoutaffectingotheroperatingpoints.Airflowandrpmsetupbasicpulsetime.2dueto意思为“归因于”、“由于所引起”。Pumping与opening/closing并列，均为动名词。本句可译为：各个活塞的泵吸作用以及进气门的开、闭动作引起了进气歧管的压力波动，像这种压力波动之类的诸多因素都将导致空气量和喷油量的控制要求发生变化。,atpartload,maximumeconomyandminimumemissionsatwide-openthrottle,maximumtorquewhileavoidingknockingatidle,maximumsmoothnessduringthrottleopening,maximumdriveabilityAirquantityandtherequirementsforcontrolofinjectedfuelcanvaryduetomanyfactorssuchasmanifold-pressurevariationsresultingfromindividualpistonpumping,andintake-valveopening/closing2.Idlingmanifoldabsolutepressurecanvaryby5kPafromanaverage42,overmorethan10%plusorminus3.Forthisandothervariations,thelambdamapinsuresthebestpossibleadjustmentoftheair-fuelratioascorrectedbyinputsthatcontrolfuelinjection,andwithoutaffectingotheroperatingpoints.Airflowandrpmsetupbasicpulsetime.3当句子中有表示增减意义的动词或分词出现时，by后面的数值表示净增减的数。介词from此处表示“距离”、“离开”、“间隔”之意。所以句中varyby5kPafromanaverage42意思为“偏离平均值42kPa的变动量达5kPa”。本句可译为：怠速时的进气歧管压力会偏离平均值42kPa，变动量达5kPa，即上、下变动10%以上。,Fig.3-5Lambdamapestablisheslambda,orair-fuelratioforeachload/speedpoint,SequentialFuelInjectionSequentialinjectionmeansdeliveringfuelseparatelyfromeachinjectorinsequenceinfiringorder.Withanincreaseincomputingpower,andanincreaseddemandforidlesmoothnessandreducedemissions,BoschMotronicML.3canprovidesequentialinjection.Eachinjectoristimedtocutoffjustbeforetheintakevalveopens.Duringacceleration,theECUcandeliveradditionalenrichingpulses,cylinderbycylinderfortherapidlychangingconditions.Inspiteofitsincreasedcost,youllseemorepulsedMotronicsequentialinjectionbecause:eachindividualinjectorpulsecanbemuchlongerthansimultaneousinjection,aslongas720crankshaftrotationlessintakevalveopening,permittingloweridlespeedslessvariationbetweencylindersinair-fuelratioforsmootheridleandreducedemissions,injectorfuel-railpressureismoreconstantbecauseonlyoneinjectoropensatatime,meaningsmootheroperationimprovedaccelerationenrichmentbecauseitcanbeappliedtothenextcylindersoftrpmlimitationbyreducingfuelflowcylinderbycylinderSomepeoplethinksequentialmeansinjectingth