Engine hybrid system.docx

Engine hybrid system.docx

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Enginehybridsystem

Enginehybridsystem

ABSTRACT

ThispaperpresentsthetechnicalapproachusedtodesignanddevelopthepowerplantfortheHondaInsight,anewmotorassisthybridvehiclewithanoveralldevelopmentobjectiveofjusthalfthefuelconsumptionofthecurrentCivicoverawiderangeofdrivingconditions.Fuelconsumptionof35km/L（Japanese10-15mode）,and3.4L/100km（98/69/EC）wasrealized.Toachievethis,anewIntegratedMotorAssist（IMA）hybridpowerplantsystemwasdeveloped,incorporatingmanynewtechnologiesforpackagingandintegratingthemotorassistsystemandforimprovingenginethermalefficiency.Thiswasdevelopedincombinationwithanewlightweightaluminumbodywithlowaerodynamicresistance.Environmentalperformancegoalsalsoincludedthesimultaneousachievementoflowemissions（halftheJapaneseyear2000standards,andhalftheEU2000standards）,highefficiency,andrecyclability.Fullconsiderationwasalsogiventokeyconsumerattributes,includingcrashsafetyperformance,handling,anddrivingperformance.

1.INTRODUCTION

Toreducetheautomobile’simpactonsocietyandtheenvironmentrequiresthatitbeincreasinglycleanerandmoreenergyefficient.Theissuesofenergyconservation,ambientairquality,andreductioninCO2emissionsareincreasingraisedasglobalenvironmentalconcerns.Onesolutionfordealingwiththeseissuesisthehybridautomobile.HondahasdevelopedandintroducedtoseveralmajormarketsworldwidetheInsight,anewgenerationofvehicledesign.TheInsightcombinesahybridpowertrainwithadvancedbodytechnologyfeaturestomeetanoverallgoalofachievingthehighestfueleconomypractical.

Thehybridpowertrainisamotorassistparallelconfiguration,termedIMAfor‘IntegratedMotorAssist’.ThispowertraincombinesahighlyefficientelectricmotorwithanewsmalldisplacementVTECengine,alightweightaluminumbody,andimprovedaerodynamicstorealize3.4L/100km（CO2:

80g/km）on98/69/ECfueleconomy.LowemissionsperformancewasalsotargetedwithemissionlevelsachievingtheEU2000.

Inadditiontorecapturingdecelerationenergy,theintegratedmotorprovideshightorqueassistduringtypicalurbandrivingaccelerations.Thisallowsasignificantreductioninenginedisplacementandhigherengineefficiency.Sustainedhillclimbingperformanceandhighspeedcruisingcapabilityareassuredbyapower-toweightratioofapproximately56kWpermetricton.NewenginetechnologyincludestheapplicationofanewVTEC（VariablevalveTimingandvalvelift,ElectronicControl）cylinderheaddesignpromotinghighefficiencyandfastcatalystactivation,andanewleanNOxcatalystsystemwhichpromotesleanburncombustionandareductioninemissions.Extensivefrictionandweightreducingfeaturesarealsoapplied.

2.DEVELOPMENTTARGETSANDCONCEPT

Developmentwasaimedattheachievementofextremelylowfuelconsumption.WesetatargetoftwicethefueleconomyofthecurrentproductionCivic,Honda’srepresentativehighfueleconomycarat7.0L/100km（93/116/EC）.Asaresult,theInsighthasthelowestfuelconsumptionintheworld,amonggasolinepassengercars.

Exhaustemissionperformanceoftentendstobesacrificedforthesakeoflowfuelconsumption.However,wealsodecidedtomatchthelowemissionsperformanceachievedbyothermassproductioncars.Considerationwasalsogiventorecyclability（anotherimportantenvironmentalissue）,crashsafetyperformance,andthebasiccarcharacteristicsincludinghandlingandstyling.

Summarizingtheabove,ourdevelopmenttargetswereasfollows:

∙Thebestfuelconsumptionperformanceintheworld

∙Ultra-lowexhaustemissions

∙Superiorrecyclability

∙Theworld'shighestlevelofcrashsafetyperformance

∙Advancedstyling

∙Practicalfeaturesandresponsivehandling

∙Comfortabletwo-seatconfigurationwithpersonalutilityspace

3.POLICIESFORFUELCONSUMPTIONREDUCTION

Inordertoestablishthetechnicalapproachforachievingthefuelconsumptiontarget,weconductedadetailedanalysisoftheenergyconsumptionofthebasecar,aCivicequippedwitha1.5literengine.Wefoundthatitwasusefultodividethetargetedefficiencygainsroughlyintothirds,asshowninFig.1,inordertoachievethelowfuelconsumptionandnumerousotherabove-mentionedgoals.Thesedivisionsareasfollows.

∙Improvementoftheheatefficiencyoftheengineitself

∙Recoveryofbrakingenergyandemploymentofidlestopusingahybridpowerplant

∙Carbodytechnologiesincludingreductionofweightandreducedaerodynamicandrollingresistance.

Aimingtoestablishabenchmarkfor21stcenturyautomobilepowertrains,wedevelopedthisnewIntegratedMotorAssistpowertrain.Thispowertrainsimultaneouslyachievesbothextremelylowfuelconsumptionof3.4L/100km,andlowexhaustgasemissionperformance,befittinganext-generationcar.

ThispaperreportsonthenewlydevelopedIMAsystem,includingtheleanburnengine,electricmotor,powercontrolunit,batterytechnology,andexhaustemissioncontroltechnologyusedinthe"HondaInsight".

4.AIMOFTHEIMASYSTEM

Whiledevelopingthisnext-generationIMAhybridsystem,weincorporatedasmanycurrentlyachievabletechnologiesandtechniquesaspossible,inordertoachievethe"world'slowestfuelconsumption".

Thefollowingfoursystemdevelopmentthemeswereestablishedinordertomeetthistarget.

1.Recoveryofdecelerationenergy

2.Improvementoftheefficiencyoftheengine

3.Useofidlestopsystem

4.Reductionofpowertrainsizeandweight

ApermanentmagnetDCbrushlessmotorislocatedbetweentheengineandthetransmission.Whendecelerating,therateofdecelerationiscalculatedforeachgearandthePCUcontrolsthemotortogenerateelectricity（recoverenergy）,whichchargesanickel-metalhydridebattery.Whenaccelerating,theamountofauxiliarypowerprovided（hereaftercalled"assist"）iscalculatedfromthethrottleopening,engineparameters,andbatterystateofcharge.ThePCUcontrolstheamountofcurrentflowingfromthebatterytothedrivemotor

4.1．RECOVERYOFDECELERATIONENERGY–Recoveringdecelerationenergythroughregenerationmakesitpossibletosupplementtheengine’soutputduringaccelerationandreducetheamountoffuelconsumed.Reducingresistanceduetorunninglosses,includingenginefrictionallosses,increasestheavailableenergyforregeneration.Inparticular,minimizingtheenginedisplacementisaneffectivemeansofreducingfriction.Enginedisplacementreductionalsohasseveralotherbenefits,suchasweightreductionandincreasedthermalefficiency.TheIMAsystemeffectivelyincreasestheamountofregenerationduringdecelerationbyoptimizingtheengineandtransmissionspecifications.

4.2.REDUCTIONOFENGINEDISPLACEMENT–Reducingenginedisplacementisaveryimportantfactorinimprovingfueleconomyofahybriddrivetrain.However,modernautomobileshavetoperformoverawidedynamicrange.Reducingthedisplacementisequivalenttoloweringthebasicperformancecharacteristicsofthecar.AsshownintheoutputcharacteristicsgraphinFig.3,theIMAsystemassiststheengineinthelowrpmrangebyutilizingthehightorqueperformancecharacteristicofelectricmotors.Themotorcanincreaseoveralltoruquebyover50%inthelowerrpmrangeusedinnormaldriving.OutputinthehighrpmrangeisincreasedbyusingaVariablevalveTimingandvalveliftElectronicControl（VTEC）engine.Thussufficientpeakpowerisassuredandmakesitpossibletouseanew,smalldisplacement1.0literengine.

4.3.ACHIEVINGLEANBURNENGINEOPERATION–Assistfromtheelectricmotor,baseduponthethrottleopening,createsquitelineartorquecharacteristics.This,inturn,improvesdriveability.Inaddition,motorassistisalsoprovidedundermoderateloadconditionstobroadenthelean-burnoperatingrange,bringingoutthefullpotentialofthenewlydevelopedleanburnengine.

4.4.IDLESTOPSYSTEM–Stoppingtheengineratherthanidlingatstopsisalsoaneffectivemeansforreducingfuelconsumption.Inordertorestarttheenginewiththeminimumamountoffuelconsumption,theengineisquicklycrankedto600rpmormorebythehightorqueintegratedmotorbeforeignitionoccurs,asshowninFig.4.Thismakesitpossibletominimizetheamountoffuelconsumed,inadditiontothefuelsavedbynotrunningtheengineatidle.

Therearemanyissuestobeconsideredwhenperformingidlestop.Theseincludejudgingthedriver'sintenttostop,preparingfortherestart,providingasmoothfeelingofdeceleration,andminimizingvibrationofthecarbodywhentheenginestops.

5.MOTORASSISTMECHANISM

5.1.DEVELOPMENTOBJECTIVES–BylimitingtheIMAmotorfunctionstoassistanceandregeneration,developmentthemeswereestablishedtoachievethefollowingtwopoints.

1.Asimpleandcompactstructure

2.Asystemweightof10%（80kg）orlessofthecompletedcarweight

6.THINPROFILEDCBRUSHLESSMOTOR

AthinandcompactDCbrushlessmotorwithengineassistandenergyregenerationfunctionswascoupledtotheenginecrank-shaft（Fig.1）.

Figure1.SectionviewofMotor

Thisisahighefficiency,compact,andlightweightpermanentmagnet-typethree-phasesynchronouselectricmotorwithamaximumoutputof10kW.Inadditiontodevelopingtechnologiestoreducetheweightandincreaseefficiency,wealsoaimedtomakethemotorasthinaspossibleinordertoachieveacompactpowertrain.Lostwaxprecisioncastingprocesswasusedfortherotor,rotatingbybendingcoupledtothecrankshaft.Thisachieveshighstrengthandlighterweight（approximately-20%）comparedwithnormalcastproducts.Fortherotormagnets,furtherimprovements