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首页 电喷柴油机发动机工作原理和系统技术介绍

电喷柴油机发动机工作原理和系统技术介绍.doc

电喷柴油机发动机工作原理和系统技术介绍

Salome丹丹
2017-10-15 0人阅读 举报 0 0 暂无简介

简介:本文档为《电喷柴油机发动机工作原理和系统技术介绍doc》,可适用于综合领域

电喷柴油机发动机工作原理和系统技术介绍船用柴油机是怎样工作的,柴油机是一种内燃机通过把燃油喷入高温高压的燃烧室而发火。船用柴油机是一种在船上使用的柴油机。其工作原理如下:一定量的新鲜空气被吸入或泵入汽缸并被运动的活塞压缩至很高的压力。空气被压缩时温度升高便点燃喷入汽缸的油雾。燃油的燃烧增加了缸内空气的热量使空气膨胀并迫使发动机活塞对曲轴做功随之驱动螺旋桨。两次喷油期间的运转过程叫一个工作循环。它由一些程序固定的过程组成。这个循环可在两个行程或四个行程内完成。四冲程柴油机的工作循环需四个独立的活塞行程即吸气压缩膨胀和排气。如果我们把吸气和排气行程与压缩和膨胀行程结合起来四冲程柴油机就变成了二冲程柴油机。二冲程循环从活塞离开其行程底部即下止点(BDC)向上运行开始气缸侧面的进气口即扫气口是打开的排气口也是打开的。经压缩的新鲜空气充入气缸通过排气口将上一行程的残气吹出。当活塞上行至其行程的时关闭进排气口随后空气在活塞上行中被压缩。当活塞上行到行程底部即上止点(TDC)时空气的压力和温度都上升到很高的数值。此时喷油器把很细的油雾喷入灼热的空气中燃烧开始在气体中产生更高的压力。随着高压气体的膨胀活塞被推动下行直到它打开排气口燃烧过的气体开始排出活塞继续下行直到它打开进气口另一个循环开始。在二冲程柴油机中曲轴转一周产生一个动力行程即做功行程而在四冲程柴油机中曲轴转两周才产生一个动力行程。这就是为什么从理论上说二冲程柴油机能产生相同尺寸的四冲程柴油机的两倍功率。然而扫气不充分和其他损失使这一优势降到大约倍。在船上每种柴油机都有他的应用。低速(即~rmin)主推进柴油机以二冲程工作。在此低速时机桨间不需减速箱。四冲程柴油机(通常以中速运转转速在~rmin)用于发电机并且有时作推进主机用减速箱提供~rmin的速度。工作循环柴油机可设计成以二冲程循环或四冲程循环工作二者解释如下:四冲程循环典型的两转四冲程循环的过程。通常从上止点(TDC发火)开始绘制从上止点(TDC扫气)开始解释。上止点又叫内止点。沿该顺时针看开始时进排气阀都是打开的(所有现代四冲程柴油机均有气阀机构)。如果柴油机是自然换气或带有径流增压气的小型高速机气阀的重叠时间即两气阀同时开启的时间将很短。排气阀将在上止点后(ATDC)º左右关闭。推进柴油机和绝大多数rmin以下运转的辅助发电柴油机几乎都采用涡轮增压并设计成在这easedsignificantly(C)topromotethesustainedandhealthydevelopmentofeconomyandsocietyAdheretothe"partyledtownship,prosperingTownship,ecovillage,projectspromotingTownshipandindustrialTownship,industryrichTownship,harmonyTownship,stabilizationcontrol"developmentstrategy,takeeconomicconstructionastheCenter,strengthenleadershipovertheeconomicworkinearnest,closelyaroundthetargetdeterminedearlierthisyeartodealwithandtrytoresolvethevariousadversefactors,paycloseattentiontotheworkEffortstopromotingtheconstructionofmajorprojectsTotransportation,waterconservancy,urbaninfrastructureconstruction,focusingonimplementationofanumberofindustrialstructureadjustmentandoptimizationandupgradingofkeyprojectsforleadingrolesCompletedhasXXvillagepassvillageHighway,andtownshiplocationlightsbrightof,andXXmeters"beautifulvillage",andtownshippublicrentalandXianghospitalspublicrental,andsetsruralhousingroomcompressedinthepistonupwardWhenthepistonuptotripthebottomofthetopdeadcenter(TDC),theairpressureandtemperaturerosetoahighvalueTheinjectortoaveryfinemistsprayedintothehotair,combustiongastoproduceahigherpressureWiththeexpansionofthehighpressuregas,thepistonisbeingpusheddownstreamuntilitopenstheexhaustport,combustiongasdischarge,thepistoncontinuesdownstreamuntilitopenstheairinlet,andanothercyclebeginsTwostrokedieselenginecrankshaftrevolutiontoproduceapowerstroke,powerstrokeinthefourstrokedieselenginecranktwoweekstoproduceapowerstrokeThisiswhytwostrokedieselenginecanproducetwicethepowerofthesamesizefourstrokedieselenginetheoryScavenging,however,isnotsufficientandotherlosses,thisadvantagedroppedtoabouttimesOnboard,eachdieselenginetohavehisapplicationLowspeed(~rmin),mainpropulsiondieseltwostrokeThislowspeed,themachinepaddledonotneedgearboxesFourstrokedieselengine(usuallyinthemediumspeedoperation,thespeedinthe~rmin)forgenerators,andsometimesforpropulsionengines,gearbox~rminspeedThedutycycledieselenginecanbedesignedasatwostrokecycleorfourstrokecycle,thetwoareexplainedasfollows:TypicalfourstrokecycletoturnthecourseoffourstrokecycleUsuallyfromthetopdeadcenter(TDC,ignition)tostartdrawingfromthetopdeadcenter(TDC,sweepgas)begintoexplainThepointisalsocalledTDCTDCSeealongtheclockwise,startingforward,theexhaustvalvesareopen(allmodernfourstrokedieselengineshavevalvebodies)Ifthedieselengineisanaturalventilationorasmallhighspeedmachinewithatherunoffpressurizedgas,thevalveoverlaptime,thetwovalvesopenatthesametimeaveryshorttimeClosetheexhaustvalveatTDC(theATDC)aboutºPropulsiondieselenginesandauxiliarypowerdieselengineoperationfollowingthevastmajorityofrminalmostallturbocharged,andaredesignedsothatatthismomentalotofscavengingairthroughouttheflowinordertocontroltheleaftemperatureInthiscase,theexhaustvalvewillremainopenuntiltheshutdownof~aftertopdeadcenterWiththepistoninitsinspiratorystrokeoutorthenextstoppointdownstream,itwillinhalealargequantityoffreshairReachesthemaximum,andcompensationfortheamountofairinhaledvalveseatedopenreductionorthesuctioneffectofinertia,theintakevalveremainsopen,untiltheendingpointofabout~º(~ºBTDC)ThisprocessiscalledtheintakevalveclosedFilledtheairandthenupwardpistoncompressiontoaboutºCDependingonthetypeandspeedofthedieselengine,aboutº~ºBTDC,thefuelinjectorisinjectedintoafinelyatomizedfuelIgnitionoffuelsprayedintothe~º(alsoaccordingtothemodel),downstreamofthepistonintheexpansionstroke,combustionperiodoftoºThepistonmovementisusuallyconducivetotheinductionofairforcombustionApproximatelytoºtheATDC,theexhaustvalveopens(EVO)SelectisquicklycylindergasemissionstotheexhaustpipeThis:(a)toretainenoughenergytodriveexhaustgasturbocharger(b)reducethecylinderpressuretothenextstoppointoftheminimumtoreducetheconsumptionofthepumpexhauststrokeQigongResidualexhaustgasupstreamofthepistondriven,~ºBTDC,theintakevalveopen,sothatoutwardflowofgasinertiacoupledwithapositivepressuredifferential(ofteninthecylinderinthere),theairontheexhaustthroughouttheairflowtocleanupthecylinderIfthedieselengineisnaturalventilation,theintakevalveopensataboutºbeforeTDCDutycycletostartagainTwostrokecycleTypicaltwostrokecycleprocess,asitsnamewithinthemeaningoftheworkcycleiscompletedwithinthecrankshaftrevolutionTwostrokedieselengineisalwaysapistontoopentheinlet,theairintakedownstreamairenteringthecylinderTheexhaustgascanbedischargedandtheadjacentexhaustportscontrolledbythesamepiston(returnsweepgas),orthroughtheexhaustportofthecylinderontheothersideofthedischarge,ordischarge(DCsweepgasthroughtheexhaustvalve)FromTDC,thecombustionhasbeencarriedouttoºaftertopdeadcenter,exhaustintakeinthenexttosolicitedopinionsandsuggestionsArticle,including:fourproblemstoDeepeningspecialregulation,StatelineStatemodified,sidechecksidemodified,totalsolutionhighlightproblematorectificationspiritcarriedoutpartypoliticallife,indepthcarriedouthearttalk,seriouscarriedoutcriticismandselfcriticalputbuiltchapterStatebusinessthroughoutactivitiesalways,fullcleanupandestablishedperfectainvolved"fourwind"aspectsofsystemprovides,newitems,amendmentperfectitems,abolitionitemsThrougheducationalpractices,"fourwinds"problemsignificantlycurb,partymembersandcadres'apparentchangeofconsciousnessandabilityofservingthemassesincreasedsignificantly(C)topromotethesustainedandhealthydevelopmentofeconomyandsocietyAdheretothe"partyledtownship,prosperingTownship,ecovillage,projectspromotingTownshipandindustrialTownship,industryrichTownship,harmonyTownship,stabilizationcontrol"developmentstrategy,takeeconomicconstructionastheCenter,strengthenleadershipovertheeconomicworkinearnest,closelyaroundthetargetdeterminedearlierthisyeartodealwithandtrytoresolvethevariousadversefactors,paycloseattentiontotheworkEffortstopromotingtheconstructionofmajorprojectsTotransportation,waterconservancy,urbaninfrastructureconstruction,focusingonimplementationofanumberofindustrialstructureadjustmentandoptimizationandupgradingofkeyprojectsforleadingrolesCompletedhasXXvillagepassvillageHighway,andtownshiplocationlightsbrightof,andXXmeters"beautifulvillage",andtownshippublicrentalandXianghospitalspublicrental,andsetsruralhousingroomº,theonlypointof~ºquicklypurgethecylinderByinertiatopromoteinthiswaytothesonicflowofexhaustairrapidlyflowsthroughthecylindertoaminimumof(gas)mixing,becauseallisnottheexhaustairwillreducetheamountofairforthenexttripInthecompressionstroke,theexhaustportshouldbeclosedbeforetheinlettotheaerationrate,butifthetwoprocessesiscontrolledbythesamepiston,andthegeometryoftheenginebacktohindertheachievementofthisThissituationindieselengineexhaustvalveInanycase,theairintakewillbethenextstoppointtoopenbeforethebottomdeadpointofviewoff,thenextstoppoint~ºturnofftheexhaustportisclosedinthesameangleintherangeThefuelinjectionbeforetopdeadcenter,about~ºangleaccordingtospeedBurningwiththefourstrokemachineisthesamefor~ºDieselenginestructure(I),FrameandrackBaseinmostcasesweldedstructure,boltedtothebaseconstitutethedoublebottomoftheshipInthehorizontalbymeansoflateralwedgepadboltintheverticalbymeansoftheendofthewedgepadboltThecrankshaftisplacedinthebasebeambearings,thesebearingsarereferredtoasthemainbearingsEachbearingconsistsoftwobearingtwobearingfromthebearingseatoftheprocessingonthebasesupport,afixedstudandbearingcapThethrustbearingislocatedintherearoftheengine,withthebasemadeofonewiththebaseunitseparatelyAshapemadeofcastironorsteelofifsteelrackonthebaseplaneisequippedwithrackmountonthebasebeamandboltedAshapedtopoftherackhasasturdyframestructurecalledscavengeThesweepgastankdividedintoseveralsections,eachwithaverticalflangeinfrontofthechaindrivedevicethroughboltacylinderpartsfusedtoachaindrivedevicetocylinderpartofthefusedThechaingeartothecrankshaftandcamshafttogether,enclosedwithintheshellofthechaindriveboxSecond,thecylinderandcylinderheadTheupperpartofthescavengeeachcylinderisequippedwithasturdycastironframeFrameworkknownasthecylinderblockcoolingwaterjacket,andwithaverticalflange,andscavengeavailableboltstoeachframeintoboththetwogroupsPedestal,rackandcylinderconnectedtoalongthroughboltstogethertoformasolidstructure,reducingtheuseofdeformationandvibrationCylinderlinermadeofcastironcylinderlinersurfaceissometimeschromeplatedCylinderlinerextendingdowntoscavengeLinerandscavengingboxatthetopofthesealbytherubberring,rubberringisinstalledinthelineronthecuttingoftheringslotOnecalledscavengingportopeningsinthecylinderlinerinsertedintothesweepgastankpartsTheairinletheightissucharrangement,whenthepistonatbottomdeadcenter,pistonalongjusttoopentheairintakeTheairinletinthecylinderlinerismadeofaboutºangle,theresultisthescavengingrotationThetopofeachcylindermadeofspecialheatresistingsteelcylinderheadclosedCylinderheadmountedonthelineratthetopoftheplane,theorientationoftheshroudbymachiningRingembeddedinthecylinderheadsofconesurfacemustbeverycarefulCylinderheadandcylindertoapplyspinintothestudinthecylinderisfixedLineronthedrillingspaceisusedforlubrication,thenewlineratthetopofairdrillingforcoolingEachcylinderheadhasalargecenterholeusedtoinstalltheexhaustvalve,aswellastwotothreeemptyforloadinginjector,andalsosomeoftheholesusedtoinstallthestartervalve,safetyvalves,indicatorvalve,aswellasTheexhaustvalvecoolingwaterchamberofimportandexportReadingmaterialtranslationASULZERmarinedieselengineOfSULZERtheRNDMtypedieselengineissingleacting,lowspeed,twostrokereversibleengineThemovementofbodiesofeachcylinderbythepiston,thepistonbar,rodandconnectedtoasinglehandlecranksolicitedopinionsandsuggestionsArticle,including:fourproblemstoDeepeningspecialregulation,StatelineStatemodified,sidechecksidemodified,totalsolutionhighlightproblematorectificationspiritcarriedoutpartypoliticallife,indepthcarriedouthearttalk,seriouscarriedoutcriticismandselfcriticalputbuiltchapterStatebusinessthroughoutactivitiesalways,fullcleanupandestablishedperfectainvolved"fourwind"aspectsofsystemprovides,newitems,amendmentperfectitems,abolitionitemsThrougheducationalpractices,"fourwinds"problemsignificantlycurb,partymembersandcadres'apparentchangeofconsciousnessandabilityofservingthemassesincreasedsignificantly(C)topromotethesustainedandhealthydevelopmentofeconomyandsocietyAdheretothe"partyledtownship,prosperingTownship,ecovillage,projectspromotingTownshipandindustrialTownship,industryrichTownship,harmonyTownship,stabilizationcontrol"developmentstrategy,takeeconomicconstructionastheCenter,strengthenleadershipovertheeconomicworkinearnest,closelyaroundthetargetdeterminedearlierthisyeartodealwithandtrytoresolvethevariousadversefactors,paycloseattentiontotheworkEffortstopromotingtheconstructionofmajorprojectsTotransportation,waterconservancy,urbaninfrastructureconstruction,focusingonimplementationofanumberofindustrialstructureadjustmentandoptimizationandupgradingofkeyprojectsforleadingrolesCompletedhasXXvillagepassvillageHighway,andtownshiplocationlightsbrightof,andXXmeters"beautifulvillage",andtownshippublicrentalandXianghospitalspublicrental,andsetsruralhousingroomThedockingstationmadeofdoublewallstructureofthelongitudinalboxgirderAshapedframeworkinstalledonthebasesupportingtherackandcylinderblock,theentirebase,AshapedframeandthecylinderblockassemblywiththroughboltstogethertoformarigidstructureInordertowithstandhorizontalcrankshaftbendingload,themainbearingcapfixedbythestrutboltsThisenhancedstructureisnecessarytowithstandthefireloadonthedieselenginestructurereachedbythecylinderheadThecrankshaftisasemimodular,thecrankarmisdesignedaspartofthequalityofbalancerotationThecylinderheadwasmadeofmonomer,andequippedwithacentralinjector,startingairvalve,safetyvalveandindicatorvalveTheconstantpressureexhaustdriventurbochargertoprovidescavengingairTherefluxsweepgasandauxiliaryblowerwithanelectricrunautomatically,sothatlowandmaneuveredLubricantsforlowandmediumvoltagesystems,lowpressuresystemtothemainbearingsandotherbearingoilsupply,thecrossheadbearingtheChineseandoilofthepressuresystem,thehingetubetooilsenttothecrossheadbearingCylinder,cylinderheadandpistoncoolingbywater,theboomofwaterintothepistonThefuelinjectionusingindependentinjectionsystem,andWoodwardhydraulicgovernorgovernorRLtypeofdieselenginebasedontheRNDMtype,thepistonstrokelengthenedtoprovidegreateroutputpowerandlowerspeedItsnewfeaturesincludesinglewalledbasewithathrustbearing,pistonheadandthemaincombustionchambercomponentsdrillaircooling,andwaterintheaircirculationclosetothehotsurfaceofthedrillBSULZERtheRTAtypedieselengineTheSULZERRTACisatypicallowspeedtwostrokecrossheadlongjourneyofmoderndieselenginesItsboremm,strokemm,speedrmin,tocylinderproductscanalsobeparticularlylargefastcontainershipproductionItsdesignandstructureandRTAseriesRTAseriescylindersizedowntommThedockingstationiscomposedofsinglewalldeepwallboxstructureweldedplatesandcastings,weldingasolidAshapedrackisequippedwithcoolingliner,formedbytheboltfusedcylinderOfthesepartsdieselrobustoverallframeworkTheentireframestructurethroughboltsverticalpreloadLinerforacastironalloyItsupperendisasolidringunits,locatedinthecylinderbody,itisunderalotofgasloadThelinerdrillingaircooling,adjustablewaterflowtomaintainthepropertemperatureLinerthelowerendofthesweepgastankwithoutcoolingDifferentheightofthecylinderlubricationtoreducecylinderwearrateCylinderheadissolidforgedsteel,drillingcoolingtoreducethermalstress,andpasstheheatofthefuelinjector,soconcentratedcoolingtheexhaustvalveseatcylinderheadcoolingwaterForexhaustvalvemadeof#nickelchromiumtitanium(Ninonic,),andthroughtheleavesonthestemrotationHeopenedhydraulicallyandclosedbyairspringaction,opentheliquidpressurefromthecamdrivencontrolmechanismPistonwithalloysteelpistonhead,andfivecompressionringinstalledintheringslotchromepistonwithashortcastironpistonskirtPistonoilcooling,shockcoolingandsmallnozzleinjection,intotheoilthroughclosetotheundersideofthepistonheadandthebackoftheholeinthepistonringgrooveCoolingoildrillinginthepistonrodfromthecrossheadofthehingerodforentryandreturnThepistonrodandmonomercrossheadisconnectedtothesurface,andcontinuouslythroughoutthelowerhalfandthetopbearingTheupperbearingmaterialforthewhitemetalbypressureoillubricationThecrossheadorientedsliderconnectedtoeachendofthecrossheadThesemiassemblycrankshaftcranktoincreasemainbearingarearecessedinthechamfer,themainbearingcapfixedbythestrutboltsinstalledintherackCamshaftgeardrive,withaservertoruninthereversetothefuelpumpandstartingairdistributorretimingThehighpressurepumpisacamdrivenvalvepumps,withvariableignitiontimingadjustmenttomaintainslowandefficientcombustionMountedonthecylinderheadoneachhighpressurepumptothesymmetricalarrangementofthreeinjectorcoolingoilInthefuelinjectorfuelinjectortheheatcycleThisdieselengineusingaDCsweepgasatconstantpressurebooster,withefficientcoolingoftheturbineturbocharger,supplementedbytwohighspeedelectricauxiliaryfanatlowspeedDieselenginestructure(II)solicitedopinionsandsuggestionsArticle,including:fourproblemstoDeepeningspecialregulation,StatelineStatemodified,sidechecksidemodified,totalsolutionhighlightproblematorectificationspiritcarriedoutpartypoliticallife,indepthcarriedouthearttalk,seriouscarriedoutcriticismandselfcriticalputbuiltchapterStatebusinessthroughoutactivitiesalways,fullcleanupandestablishedperfectainvolved"fourwind"aspectsofsystemprovides,newitems,amendmentperfectitems,abolitionitemsThrougheducationalpractices,"fourwinds"problemsignificantlycurb,partymembersandcadres'apparentchangeofconsciousnessandabilityofservingthemassesincreasedsignificantly(C)topromotethesustainedandhealthydevelopmentofeconomyandsocietyAdheretothe"partyledtownship,prosperingTownship,ecovillage,projectspromotingTownshipandindustrialTownship,industryrichTownship,harmonyTownship,stabilizationcontrol"developmentstrategy,takeeconomicconstructionastheCenter,strengthenleadershipovertheeconomicworkinearnest,closelyaroundthetargetdeterminedearlierthisyeartodealwithandtrytoresolvethevariousadversefactors,paycloseattentiontotheworkEffortstopromotingtheconstructionofmajorprojectsTotransportation,waterconservancy,urbaninfrastructureconstruction,focusingonimplementationofanumberofindustrialstructureadjustmentandoptimizationandupgradingofkeyprojectsforleadingrolesCompletedhasXXvillagepassvillageHighway,andtownshiplocationlightsbrightof,andXXmeters"beautifulvillage",andtownshippublicrentalandXianghospitalspublicrental,andsetsruralhousingroomFirst,thepistonandpistonrodThepistonheadandpistonmadebythelowerpartofacastironpistonskirtandtheupperpartofaheatresistantsteelThemtogetherwithboltsandfixedonthepistonrodPistonpartsbetweenthelocationofthegrooveofthepistonheadturningandpositioningpinfixedEachpistonisequippedwithsixpistonrings,pistonringmountedontheheadchromeringslotofthetoppistonringisanarrowringwithobliqueincisionimmediatelygoonthetwopistonringswithoverlappingridethemouthofthewidering,thatringinthebottomoftheoilscraperringAllpistonringstopandbottomoftheouteredgeofaslightchamfertoleftinthelinerofthenewpistonringrunningduringthefilmInordertocontrolthethermalstress,someofthemoderndieselengineusingthinwalledcentralcoolingpistonInthiscase,apluginwithinthepistonhead,usedforthecoolingfloworientedtoenhancethetraditional"chickentailshockeffectThepistonrodfromthetopflangetotherelativepositionofthecrossheadcenterboringAlongtubefromtheholeintothenearbottomoftheholeTubeouterdiametersmallerthanthediameterofthehole,sotoformanannularspacebetweenthepistonrodandtubeThebottomofthepistonroddiameterdecreases,insertintheholewithinthecrossheadandthecrossheadandpistonrodfasteningnutsThepistonrodisequippedwithalocatingpintoensurethatthecorrectassemblyofthevariouscomponentsAtthejournalofthecrossheadatbothends,eachequippedwithacrossheadsliderCrossheadsliderinsidetheengineframecrossheadguidesorientedCrossheadsliderisdeterminedbythepositioningpininthelocationofthecrosshead,coneheadboltsecuredtothecrossheadsolicitedopinionsandsuggestionsArticle,including:fourproblemstoDeepeningspecialregulation,StatelineStatemodified,sidechecksidemodified,totalsolutionhighlightproblematorectificationspiritcarriedoutpartypoliticallife,indepthcarriedouthearttalk,seriouscarriedoutcriticismandselfcriticalputbuiltchapterStatebusinessthroughoutactivitiesalways,fullcleanupandestablishedperfectainvolved"fourwind"aspectsofsystemprovides,newitems,amendmentperfectitems,abolitionitemsThrougheducationalpractices,"fourwinds"problemsignificantlycurb,partymembersandcadres'apparentchangeofconsciousnessandabilityofservingthemassesincreasedsignificantly(C)topromotethesustainedandhealthydevelopmentofeconomyandsocietyAdheretothe"partyledtownship,prosperingTownship,ecovillage,projectspromotingTownshipandindustrialTownship,industryrichTownship,harmonyTownship,stabilizationcontrol"developmentstrategy,takeeconomicconstructionastheCenter,strengthenleadershipovertheeconomicworkinearnest,closelyaroundthetargetdeterminedearlierthisyeartodealwithandtrytoresolvethevariousadversefactors,paycloseattentiontotheworkEffortstopromotingtheconstructionofmajorprojectsTotransportation,waterconservancy,urbaninfrastructureconstruction,focusingonimplementationofanumberofindustrialstructureadjustmentandoptimizationandupgradingofkeyprojectsforleadingrolesCompletedhasXXvillagepassvillageHighway,andtownshiplocationlightsbrightof,andXXmeters"beautifulvillage",andtownshippublicrentalandXianghospitalspublicrental,andsetsruralhousingroo
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电喷柴油机发动机工作原理和系统技术介绍

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