发动机类毕业设计外文翻译.docx

发动机类毕业设计外文翻译.docx

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发动机类毕业设计外文翻译

1Summarize

Outlineusesamorecompactdesignalongwiththeengineandhasinabigway,theengineproducesthewasteheatdensityalsoobviouslyincreasesalongwithit.Someessentialregions,ifaroundarowoftyrevalveradiatesthequestiontohavefirsttoconsider,thecoolingsystemevenifappearsthesmallbreakdownalsopossiblytocreatethedisasterinsuchregionconsequence.Theenginecoolingsystemradiationabilitygenerallyshouldsatisfywhentheenginefullloadradiationdemand,becausethistimeengineproducesthequantityofheatisbiggest.However,whenpartialloads,thecurrentcapacitywhichthecoolingsystemcanhavethepowerloss,whichthewaterpumpingstationprovidestherefrigerantcurrentcapacitysurpassesneeds.Wehopedstartsthestartingtimetobeasfaraspossibleshort.Becauseenginetimedischargespollutantmore,theoilconsumptionisalsobig.Thecoolingsystemstructurehasamoretremendousinfluencetotheenginecoldstartingtime.

2Characteristicsofmodernenginecoolingsystem

Modernenginesseriescharacteristictraditioncoolingsystemfunctionreliablyprotectstheengine,butalsoshouldhavethefunctionwhichtheimprovementfueleconomyandreducesdischarges.Therefore,themoderncoolingsystemmustsynthesizeundertheconsiderationthefactor:

Engineinteriorfrictionloss;Coolingsystemwaterpumppower;Burningboundarycondition,likecombustionchambertemperature,completedensity,completetemperature.Theadvancedcoolingsystemusessystematized,themodulardesignmethod,theoverallplanconsideredeachinfluencefactor,causesthecoolingsystembothtoguaranteetheenginenormalwork,andenhancestheengineefficiencyandthereductiondischarges.

2.1ThetemperaturessetpointTemperatureshypothesesfiringinburstsmotiveoperatingtemperaturelimitvaluearedecidedbyarowoftirevalvetheperipheralregionmaximumtemperature.Themostidealsituationisaccordingtothemetaltemperaturebutisnottherefrigeranttemperaturecontrolcoolingsystem,likethiscanprotecttheenginewell.Becausethecoolingsystemhypothesiscoolingtemperatureisbythefullloadtimemostisbigisthefoundation,therefore,engineandcoolingsysteminpartialloadstimeisatnottootheperfectcondition,whenurbandistricttravelandlowspeedtravel,canhavethehighoilconsumptionanddischarge.Supposesthefixedpointthroughthechangerefrigeranttemperaturetobepossibletoimprovetheengineandthecoolingsysteminpartialloadstimeperformance.Accordingtoarowoftyrevalvetheperipheralregiontemperaturelimitvalue,mayelevateeitherreducetherefrigerantorthemetaltemperaturesupposesthefixedpoint.Elevatesorreducedtemperatureallrespectivelyhasthecharacteristic,thisisdecidedthegoalwhichachievedtothehope.

2.2EnhancesthetemperatureEnhancesthetemperaturetosupposethefixed-pointenhancementoperatingtemperaturetosupposethefixedpointisonekindofcomparisonthemethodwhichwelcome.Enhancesthetemperaturetohavemanymerits,itdirectlyaffectstheenginelossandthecoolingsystemeffectaswellastheenginedischargingformation.WillenhancetheoperatingtemperaturetoenhancetheengineMacreducetheenginetorubwears,reducestheenginefueloilconsumption.Theresearchindicatedthat,theengineoperatingtemperaturetorubsthelosstohavetheverytremendousinfluence.Dischargesthetemperaturetherefrigeranttoenhanceto150℃,causesthecylindertemperaturetoelevateto195℃,theoilconsumptiondrops4%-6%.Maintainstherefrigeranttemperaturein90-115℃scope,causestheenginemachineoilthemaximumtemperatureis140℃,thenoilconsumptioninpartialloadstimedrops10%.Enhancestheoperatingtemperaturealsoobviousinfluencecoolingsystemthepotency.Enhancestherefrigerantorthemetaltemperaturecanimprovetheengineanddispersethesteamheattransfertransmissiontheeffect,reducestherefrigerantthespeedofflow,reducesthewaterpumptheratedpower,thusreducestheenginethepowerdissipation.Inaddition,mayselectthedifferentmethod,furtherreducestherefrigerantthespeedofflow.

2.3ReducethetemperaturessetpointReducedtemperaturessupposethefixedpointtoreducethecoolingsystemtheoperatingtemperaturetobepossibletoenhancetheenginechargeefficiency,reducestheinlettemperature.Thistothecombustionprocess,thefueloilefficiencyanddischargesadvantageously.Thereducedtemperaturesupposesthefixedpointtobeallowedtosavetheenginemovementcost,enhancesthepartservicelife.Theresearchindicated,ifthecylinderheadtemperaturereducesto50℃,theignitionangleofadvancemay3℃Abutnothavetheengineknockaheadoftime,thechargeefficiencyenhances2%,theengineoperationalfactorimprovement,ishelpfultotheoptimizedcompressionratioandtheparameterchoice,obtainsthebetterfueloilefficiencyanddischargestheperformance.

2.4PrecisecoolingsystemPrecisecoolingsystemsprecisecoolingsystemmainlymanifestsinthecoolingjacketstructuraldesignandintherefrigerantspeedofflowdesign.Inprecisecoolingsystem,hotessentialarea,ifaroundarowoftyrevalve,therefrigeranthasangreaterspeedofflow,theheattransferefficiencyishigh,therefrigerantgradientoftemperaturechangesslightly.Sucheffectcomesfromtoreducetheseplacerefrigerantchannelsthelateralsection,enhancesthespeedofflow,reducesthecurrentcapacity.Theprecisecoolingsystemdesignkeyliesinthedeterminationcoolingjacketthesize,thechoicematchcoolingwaterpump,guaranteedthesystemtheradiationabilitycansatisfywhenthelowspeedbigloadessentialregionoperatingtemperaturedemand.Theenginerefrigerantspeedofflowrangeofvariationisquitebig,fromtime1m/stomaximumworkratetime5m/s.Thereforeshouldconsideredthecoolingjacketandthecoolingsystemwholethat,mutuallysupplemented,displaybiggestpotential.Theresearchindicatedthat,usestheprecisecoolingsystem,intheengineentireworkrotationalspeedscope,therefrigerantcurrentcapacitymaydrop40%.Coversthecoolingjackettotheaircylindertheprecisedesign,maymaketheordinaryspeedofflowtoenhancefrom1.4m/sto4m/s,greatlyenhancesthecylindercoverorcapthermalconductivity,cylindercoverorcapmetaltemperaturedropto60℃.

2.5DivergencestypescoolingsystemDivergencestypescoolingsystemdivergencetypecoolingsystemforotheronekindofcoolingsystem.Inthiskindofcoolingsystem,thehineoiltemperature,willcylindercoverorcapfriendlycylinderbodycoolsbyrespectivereturnroute,thecylindercoverorcapfriendlycylinderbodyhasthedifferenttemperature.Thedivergence-likecoolingsystemhastheuniquesuperiority,maycauseengineeachparttosupposethefixed-pointworkatthemostsuperiortemperature.Thecoolingsystemoverallefficiencyachievesinabigway.Eachcoolingreturnroutewillsupposeunderthefixedpointorthespeedofflowinthedifferentcoolingtemperatureworks,willcreatetheidealenginetemperaturedistribution.Theidealenginehotactivestatusisthecylinderheadtemperaturelowerbuttheaircylinderbodytemperaturerelativeishigher.Thecylinderheadtemperatureislowermayenhancethechargeefficiency,increases.Thetemperatureislowalsogreatlymaypromotecompletelytoburn,reducesCO,HCandtheNOxformation,alsoenhancestheoutput.Thehigheraircylinderbodytemperaturecanreducethefrictiontolose,directlyimprovesthefueloilefficiency,indirectlyreducesinthecylinderthepeakvaluepressureandthetemperature.Thedivergencetypecoolingsystemmaycausethecylindercoverandthecylinderbodytemperaturediffers100℃.Thecylindertemperaturemayreachashighas150℃,butthecylindercovertemperaturemayreduce50℃,reducesthecylinderbodytorubloses,reducestheoilconsumption.Thehighercylinderbodytemperaturecausestheoilconsumptiontoreduce4%-6%,whenpartialloadsHCreduces20%-35%.Whenthedamperallopens,thecylindercoverandthecylinderbodytemperaturesupposesthedefinitevaluetobepossibletomoveto50℃and90℃,improvesthefueloilconsumption,thepoweroutputfromthewholeanddischarges.

2.6ControllablecoolingsystemControllableenginecoolingsystemtraditionenginecoolingsystembelongstothepassiveform,thestructuresimpleorthecostislow.Thecontrollablecoolingsystemmaymakeupatpresentcoolingsystemtheinsufficiency.Nowthecoolingsystemdesignstandardsolvestimethefullloadradiationproblem,thuspartiallyshoulderstimetheoversizedradiationabilitywillcausetheenginepowerwaste.Thistothelightvehiclesaidespeciallyobvious,thesevehiclesmajoritytimeallunderthepartialloadsgointheurbandistrict,onlyusesthepartialenginepower,causesacoolingsystemhigherloss.Inordertosolvetheenginetogetdownthehotquestioninthepeculiarcircumstance,thepresentcoolingsystemvolumewasbigger,causestheevaporationefficiencytoreduce,hasincreasedthecoolingsystempowerdemand,lengthenedtheengineduringwarmmachine-hour.Thecontrollableenginecoolingsystemgenerallyincludesthesensor,theexecutionandtheelectricallycontrolledmodule.Thecontrollablecoolingsystemcanactaccordingtotheengineworkingconditionadjustmentcoolingquantity,reducestheenginepowerloss.Inthecontrollablecoolingsystem,theexecutionforthecoolingwaterpumpandthethermostat,generallyandthecontrolvalveiscomposedbytheelectricallyoperatedwaterpump,mayactaccordingtorequeststoadjustthecoolingquantity.Temperaturesensorforasyste