汽車專業(yè)英語(yǔ)讀譯教程 第3版 課件 8-U4TB Operation of the Motronic System

UNIT4

GASOLINEFUELINJECTION

TEXTB

OperationoftheMotronicSystem

PROFESSIONALENGLISH

UNIT4

GASOLINEFUELINJECTION

TEXTB

OperationoftheMotronicSystem

StartControl(Fuel,IgnitionTiming,Air)

Post-Start

Warm-Up

Closed-LoopOperation

Part-ThrottleAcceleration

Full-LoadAcceleration

KnockControl

RPMLimitation

CoastingCut-Off本次課學(xué)習(xí)內(nèi)容本次課學(xué)習(xí)目標(biāo)掌握MOTRONIC系統(tǒng)的控制原理掌握有關(guān)控制原理的專用術(shù)語(yǔ)了解翻譯技巧—句子成分轉(zhuǎn)換NEWWORDSflood[fl?d]v.充滿，淹沒(méi)，溢出；n.洪水compensate['k?mpenseit]v.補(bǔ)償，償還formation[f?:'mei∫?n]n.形成，形成量turbocharge['t?:bout∫ɑ:?]v.用渦輪增壓turbo['t?bou]n.渦輪增壓，渦輪增壓器intercooler[?int?'ku:l?]n.中間冷卻器，中冷器sense[sens]v.理解，感到，感受，檢測(cè)override[?ouv?'raid]v.超過(guò)（越），越過(guò)，壓倒，占優(yōu)勢(shì)overswing['ouv?swi?]v.擺動(dòng)過(guò)大lambda['l?md?]n.λ值，過(guò)量空氣系數(shù)，氧傳感器NEWWORDSflood[fl?d]v.充滿，淹沒(méi)，溢出；n.洪水compensate['k?mpenseit]v.補(bǔ)償，償還formation[f?:'mei∫?n]n.形成，形成量turbocharge['t?:bout∫ɑ:?]v.用渦輪增壓turbo['t?bou]n.渦輪增壓，渦輪增壓器intercooler[?int?'ku:l?]n.中間冷卻器，中冷器sense[sens]v.理解，感到，感受，檢測(cè)override[?ouv?'raid]v.超過(guò)（越），越過(guò)，壓倒，占優(yōu)勢(shì)overswing['ouv?swi?]v.擺動(dòng)過(guò)大lambda['l?md?]n.λ值，過(guò)量空氣系數(shù)，氧傳感器endanger[in'dein??]v.危及trait[treit]n.特性，顯著的特點(diǎn)harmonics[hɑ:'m?niks]n.諧波[音]，諧波分量NEWWORDSrecognition[?rek?g'ni∫(?)n]n.承認(rèn)，賞識(shí)，贊譽(yù)modify['m?difai]v.更改，修改stratification[?str?tifi'kei∫?n]n.成層，分層cutback['k?tb?k]n.減少scope[skoup]n.范圍，領(lǐng)域，見(jiàn)識(shí)，示波器，指示器simultaneous[?sim?l'teinj?s]a.同時(shí)的，同時(shí)發(fā)生的，同步的coast[koust]v.滑行，滑翔，沿海岸航行；n.海岸，沿岸cut-off['k?t?f]n.切斷，關(guān)閉，停車coastdown['koustdaun]n.降低，下降，滑行blank[bl??k]ad.空白的，空著的，沒(méi)有表情的；n.空白stall[st?:l]v.失速，熄火，（速度不夠）停車[停止轉(zhuǎn)動(dòng)]refinement[ri'fainm?nt]n.精致，文雅，精巧resume[ri'zju:m]v.恢復(fù),重新開(kāi)始

PHRASESANDEXPRESSIONS

portinjector進(jìn)氣道噴油器startinjector起動(dòng)噴油器，冷起動(dòng)噴油器thermo-timeswitch溫控定時(shí)開(kāi)關(guān)turbochargedcar渦輪增壓轎車air-fuelratio空燃比knocksensor爆燃傳感器passengercompartment乘客艙，乘員室knockcontrolregulator爆燃控制調(diào)節(jié)器besortedfrom與…分開(kāi)，從…揀出scopeset示波器Inthissection,let'slookatoperatingconditionstoseehowMotroniccontrolsinjectionandignitionaswellasidle-speedbypassairforgoodenginemanagement[1].StartingStartControl,FuelInmostMotronics,startenrichmentisprovidedbytheportinjectorsratherthantheseparatestartinjector/thermo-timeswitch.Forstartcontrol,theimportantinputsarerpmandenginetemperature.Thecontrolunitmonitorscrankingrpm,andalsothenumberofrevolutionssincethetimecrankingbegan[2].Theinjectionpulsesmaybelongerthannormal.

OperationoftheMotronicSystem

OperationoftheMotronicSystem

Butatlowenginetemperatures,thecontrolunitmaydeliverinsteadseveralshorterinjectionpulsesperrevolutiontoimprovestarting.Remember,theseare10millisecondpulsesinapulseperiod,orcrankshaftrevolutiontimeof200ms.Forhotstarts,orhighintakeairtemperatures,timingwillberetardedbecauseahotcylindercanfireeasierwhilethepistonisrisingatcrankingrpm.Retardedtimingpreventsknockingthatcanoccurinhigh-compressionengines,andmaybemaskedbythestartersound.

OperationoftheMotronicSystem

Topreventflooding,fuelquantitywillcutbackafterameasurednumberofrevolutions,oraftertheenginehasreachedacrankingrpmthatistemperaturerelated,forexample200-300rpm.StartControl,IgnitionTimingWithacoldengineatlowcrankingspeeds,timingwillbecontrollednearTDC.Fornormalcrankingrpm,alargeadvanceintimingmightfiretooearly,damagingthestarter.Further,startingwouldbedifficultifnotimpossible.Withacoldengineathighercrankingrpm,however,timingwillbeadvancedforbetterstarting.

OperationoftheMotronicSystem

StartControl,AirAsinL-Jetronic,theidle-speedstabilizerisnormallydrivenopenmorebyincreaseddwellsignalstoprovideextrabypassairforcoldstarting.Post-StartPost-start-the5-30secondswhenyouwanttheenginetokeeprunningafteryoureleasethekeyfromCRANK-isaffectedbyenginetemperatureaswellasatimerinthecontrolunit.Colderenginesgetmorefuelinjected.Also,colderenginesgetmoretimingadvance.Basedonthestart-uptemperature,andthetimesincestart,post-startenrichmentisgraduallyreduced.Theidle-speedstabilizermaintainsrpm.

OperationoftheMotronicSystem

Warm-UpDuringwarmup,themostimportantinput,besidesengineloadandrpmforbasicpulsetime,isenginetemperature.ThecontrolunitincludesaROMmapofwarm-upcharacteristicstoapplyacorrectionfactorbasedonloadandenginespeed,greateratlowloadsandrpmthanathighloadsandrpms[3],SeeFig.4-7.Controlunitoutputsincludeinjectionpulsesforthepropermixture,ignitiontimingfordriveability(advanceunderpart-loadacceleration,retardondecelerationtoreduceHCemissions),andidlestabilizationtohelpkeeptheenginerunningatidle.

OperationoftheMotronicSystem

Remember,duringwarm-up,thetemperatureofthelambdasensorisimportant.Unheatedlambdasensorscanbeheatedfasterbychangingignitiontiming.Motronicretardstimingtocauseahotterexhaust.Thatheatstheoxygensensormuchquickerandalsoheatsthecatalyticconverterfasterformoreefficiency.Fig.4-7Warm-upcorrectionfactors

OperationoftheMotronicSystem

Closed-LoopOperation

Basedontheinputsofawarmengine,andoxygen-sensorvoltagewhenhot,thesystemnormallyoperatesclosed-loop.Theoxygensensorfine-tunesthefuel-injectiondeliveryforproperair-fuelratios.Foreverycombinationofinputs,thecontrolunitlooksinitsmemoryforthebesttiming,thebestdwellangle,thebestlambda,orair-fuelratio[4].Onthebasisofenginetemperature,Motroniccontrolsignitiontimingwithindependentcalibrationsforstarting,idling,deceleration,andacceleration,bothpart-loadandfull-loadorWOT(WideOpenThrottle).Forexample,controloftimingadvanceatidlereducestheneedforidlefuelenrichment.

OperationoftheMotronicSystem

OperationoftheMotronicSystem

Part-ThrottleAccelerationJustasinL-Jetronic,theoverswingsignaloftheair-flowsensorincreasesfueldelivery,compensatedbytemperature.Forair-masssensors,therateofincreaseofthevoltagesignalsacceleration.Duringpart-throttleacceleration,thenormalpulseforsteadycruiseincreasesforjustaboutonesecondwhileyouopenthethrottle.Thenthepulsecutsbackevenastheenginepicksupspeed;thissavesfuelandreducesemissions.

OperationoftheMotronicSystem

Inaddition,ignitiontimingcanberetardedtoavoidthebriefaccelerationknockthatcouldoccurforthefirstfewcyclesofengineacceleration.IgnitiontimingcontrolalsoreducestheformationofNOx,whichisnormalwithacceleration.Rateofignitiontimingchangeisalsocontrolled;·toavoidknocking,thecontrolunitallowsfastchange·toreducejerkduringtransition,thecontrolunitnormallychangesignitionadvancegraduallyFull-LoadAccelerationFull-loadenrichmentissignaledbythethrottleswitch.Aslongasthethrottleisfull-open,longerinjectionpulseswillbedeliveredforenrichment.Richmixturesreducethetendencytoknock.Thisenrichmentisbasedsolelyonrpm,andprogrammedfromenginetests.Theair-flowsignalisignored.Atthesametimeasrpmandthrottlepositioncontrolfull-loadinjectionenrichment,airtemperatureandenginetemperaturesupplyinputstocontroltheadvanceofignitiontimingforbestaccelerationwithoutapproachingknock[5].

OperationoftheMotronicSystem

OperationoftheMotronicSystem

Forengineswithoutknocksensors,timingadvanceisbasedonenginetestdatastoredinthetimingmap.Theenginecanoperateclosetotheignition-advancelimit,developingmaximumtorqueovertheentirerpmrangewithleastchanceofknockingbasedonthreefactors:1.thetimingcurvecanbeprogrammedspecificallyforeachengineoperatingpoint。2.thesystemoperateswithnarrowtolerancesandfreedomfrommechanicalwear3.timingiscompensatedaccordingtoenginetemperatureandintake-airtemperature

OperationoftheMotronicSystem

Insometurbochargedcars,asecondair-temperaturesensorismountedinthemanifolddownstreamoftheturboortheintercoolertosensethetemperatureoftheairenteringtheengine.Thisisaspecialfast-responsesensoroverridingthefirstair-temperaturesensortohandlethequickchangesintemperaturethatcanoccurduringfull-throttleacceleration.

OperationoftheMotronicSystem

KnockControlProgrammedtimingaccuracy,evenwithcompensations,canbeimprovedbyaknock-sensorsystemthatcausestimingtoadvancetojustbeforethepointwhereknockcoulddamagetheengine.Withaknocksensorcontrollingtimingadvanceinaseparateclosed-loopsystem,poweroutputcanbemaximizedwithoutendangeringtheengine.Someengines,particularlyturbochargedengines,includeknocksensorstopickupvibrationsfromtheengineatthefirstsignsofknock.TSomesystemsusetwocontroltraits,mountedinsidethepassengercompartment,oneforMotronic,andarelatedknockcontrolregulator,calledKLR.Knock-sensinginputshelpbothcontrolunitstoworktogether.hefirstandfastestoutputchangesthetiming.Iftheengineisturbocharged,thesecondoutputcontrolstheboost.IntheMotronicknownasML3,knocksensingandenginemanagementarecombinedinonecontrolunit.Whentheengineknocks,itvibrateswithcharacteristicfrequenciesof5-10kilohertztogetherwithcorrespondingharmonics.Thesevibrationsmustbesortedfromotherenginevibrationsinarecognitioncircuitinthecontrolunit.

OperationoftheMotronicSystem

OperationoftheMotronicSystem

TheMotroniccontrolunithasaccurateinformationoncrankshaftpositionandfiringordersoitispossibletodeterminewhichcylinderisknocking(onecylinderusuallyknocksbeforetheothers).Further,circuitsoperatewithsuchspeedthatignitiontimingcanberetardedonlyfortheknockingcylinder,andadvancedforthefiringofthenextcylinder.Eachknocksignalcanmodifytiminginmilliseconds.Whenignitionretardeliminatestheknock,timingisadvancedslowlyinstepstotheoriginalvalueoruntilknockingagainoccurs.

OperationoftheMotronicSystem

Onturbochargedengines,ifknockcontinuesforseconds,boostcontrolreducesmanifoldpressure.Knockcontrolpermitsmoreboost,andhighercompressionratiosforgreaterpower.Automatically,ittendstoadjustfortheoctane-ratingofthefuelbeingburned.Withprecisecontrolofignitiontimingandturboboost,enginescanbedesignedwithhighercompressionratiosforgreaterpoweroutput.Onallengines,theknockinglimitsdependonmanyfactors:·intakeairtemperature·enginetemperature·enginedeposits·combustion-chamberform·mixturecomposition,A/Fratio,andstratification·fuelquality·airdensity

OperationoftheMotronicSystem

OperationoftheMotronicSystem

Foryears,drivershaveknownthatusinghigher-octanefueldidnotaddtoenginepowerunlessignitiontimingwasadjustedatthedistributortotakeadvantageoftheimprovedanti-knockindex.Now,withknocksensorsandclosed-loopignition-advancecontrol,poweroutputcandependontheanti-knockindexofthefuelbeingburned.Itisnotunusualtoseeenginepowerspecificationsincludetheanti-knockindexofthefueltobeused[6].

OperationoftheMotronicSystem

RPMLimitationIftherpmsignalisgreaterthanmax-allowablerpmstoredinthecomputermemory,thecontrol-unitsignalsacutbackofthefuel-injection