汽車發(fā)動(dòng)機(jī)外文翻譯文獻(xiàn)（文檔含中英文對(duì)照即英文原文和中文翻譯）AUTOMOTIVEENGINElEngineClassificationandOverallMechanicsTheautomobileenginescanbeclassifiedaccordingto:(1)cycles,(2)coolingsystem,(3)fuelsystem,(4)ignitionmethod,(5)valvearrangement,(6)cylinderarrangement,(7)enginespeed.Enginesusedinautomobilesaretheinternalcombustionheatengines.Theburningofgasolineinsidetheengineproduceshighpressureintheenginecombustionchamber.Thishighpressureforcepistontomove,themovementiscarriedbyconnectingrodstotheenginecrankshaft.Thecrankshaftisthusmadetorotate:therotarymotioniscarriedthroughthepowertraintothecarwheelssothattheyrotateandthecarmoves.Theenginerequiresfourbasicsystemstorun(Fig.2-1).Dieselenginesrequire threeofthesesystems.Theyarefuelsystem,ignitionsystem(exceptdiesel),lubricatingsystemandcoolingsystem.However,threeotherrelatedsystemsarealsonecessary.Thesearetheexhaustsystem,theemission-controlsystem,andthestartingsystem.Eachperformsabasicjobinmakingtheenginerun.Fig.2-1Theengineconstruction2EngineOperatingPrinciplesIS— 盤L3USvalveTheengineconstruction2EngineOperatingPrinciplesIS— 盤L3USvalvepistonCTflljkFig.2-2EnginetermsTheterm“stroke”uiedtodescribethemovementofthepistonwithinthecylinder.Themovementofthepistonfromitsuppermostposition(TDC,topdeadcenter)toitslowestposition(BDC,bottomdeadcenter)iscalledastroke.Theoperatingcyclemayrequireeithertwoorfourstrokestocomplete.Mostautomobileenginesoperateonthefourstrokecycle(Fig.2-2).Infour-strokeengine,fourstrokesofthepistoninthecylinderarerequiredtocompleteonefulloperatingcycle.Eachstrokeisnamedaftertheaction.Itperformsintake,compression,power,andexhaustinthatorder(Fig.2-3).Intakestroke CompressionstrokePowerstroke ExhauststrokeFig.2-3Four-stroke-cyclegasolineengineTheintakestrokeTheintakestrokebeginswiththepistonnearthetopofitstravel.Asthepistonbeginsitsdescent,theexhaustvalveclosesfully,theintakevalveopensandthevolumeofthecombustionchamberbeginstoincrease,creatingavacuum.Asthepistondescends,anair/fuelmixtureisdrawnfromthecarburetorintothecylinder throughtheintakemanifold.Theintakestrokeendswiththeintakevalveclosejustafterthepistonhasbegunitsupstroke.CompressionstrokeAsthepistonismovedupbythecrankshaftfromBDC,theintakevalvecloses.Theair/fuelmixtureistrappedinthecylinderabovethepiston.Futurepistontravelcompressestheair/fuelmixturetoapproximatelyone-eighthofitsoriginalvolume(approximately8:1compressionratio)whenthepistonhasreachedTDC.Thiscompletesthecompressionstroke.PowerstrokeAsthepistonreachesTDConthecompressionstroke,anelectricsparkisproducedatthesparkplug.Theignitionsystemdeliversahigh-voltagesurgeofelectricitytothesparkplugtoproducethespark.Thesparkignites,orsetsfireto,theair/fuelmixture.Itnowbeginstoburnveryrapidly,andthecylinderpressureincreasestoasmuchas3-5MPaorevenmore.Thisterrificpushagainstthepistonforcesitdownward,andapowerfulimpulseistransmittedthroughtheconnectingrodtothecrankpinonthecrankshaft.Thecrankshaftisrotatedasthepistonispusheddownbythepressureaboveit.ExhauststrokeAttheendofthepowerstrokethecamshaftopenstheexhaustvalve,andtheexhauststrokebegins.Remainingpressureinthecylinder,andupwardmovementof thepiston,forcetheexhaustgasesoutofthecylinder.Attheendoftheexhauststroke,theexhaustvalveclosesandtheintakevalveopens,repeatingtheentirecycleofeventsoverandoveragain.EngineBlockandCylinderHeadEngineBlockTheengineblockisthebasicframeoftheengine.Allotherenginepartseitherfitinsideitorfastentoit.Itholdsthecylinders,waterjacketsandoilgalleries(Fig.2-4).Theengineblockalsoholdsthecrankshaft,whichfastenstothebottomoftheblock.Thecamshaftalsofitsintheblock,exceptonoverhead-camengines.Inmostcars,thisblockismadeofgrayiron,oranalloy(mixture)ofgrayironandothermetals,suchasnickelorchromium.Engineblocksarecastings.Fig.2-4V6engineblockSomeengineblocks,especiallythoseinsmallercars,aremadeofcastaluminum.Thismetalismuchlighterthaniron.However,ironwearsbetterthanaluminum.Therefore,thecylindersinmostaluminumenginesarelinedwithironorsteelsleeves.Thesesleevesarecalledcylindersleeves.Someengineblocksaremadeentirelyofaluminum.CylinderSleevesCylindersleevesareusedinengineblockstoprovideahardwearingmaterialforpistonsandpistonrings.Theblockcanbemadeofonekindofironthatislightandeasytocastwhilethesleevesusesanotherthatisbetterabletostandupwearandtear.Therearetwomaintypesofsleemaintypesofsleeves:dryandwet(Fig.2-5).DrysleeveWetsleeveFig.2-5CylindersleeveCylinderHeadThecylinderheadfastenstothetopoftheblock,justasarooffitsoverahouse.Theundersideformsthecombustionchamberwiththetopof thepiston. Inlineengineoflightvehicleshavejustonecylinderheadforallcylinders;largerin-lineenginescanhavetwoormore.Just aswithengineblocks,cylinderheads canbemadeofcastironoraluminumalloy.Thecylinderheadcarriesthevalves,valvespringsandtherockersontherockershaft, thispartofvalvegearbeingworkedbythepushrods.Sometimesthecamshaftisfitteddirectlyintothecylinderheadandoperatesonthevalveswithoutrockers.Thisiscalledanoverheadcamshaftarrangement.GasketThecylinderheadisattachedtotheblockwithhigh-tensilesteelstuds.Thejointbetweentheblockandtheheadmustbegas-tightsothatnoneoftheburningmixturecanescape.Thisisachievedbyusingcylinderheadgasket.Gasketsarealsousedtosealjoinsbetweentheotherparts,suchasbetweentheoilpan,manifolds,orwaterpumpandtheblocks.OilPanTheoilpanisusuallyformedofpressedsteel.Theoilpanandthelowerpartofcylinderblocktogetherarecalledthecrankcase;theyenclose,orencase,the

crankshaft.Theoilpumpinthelubricatingsystemdrawsoilfromtheoilpanandsendsittoallworkingpartsintheengine.Theoildrainsoffandrundownintothe pan.Thus,thereisaconstantcirculationofoilbetweenthepanandtheworkingpartsoftheengine.PistonAssembly,pistonrings,Thepistonpin,ConnectingRods,CrankshaftsAndFlywheelPistonPistonringsandthepistonpinaretogethercalledthepistonassembly(Fig.2-6).Fig.2-6Piston,pistonringsandconnectingrodFig.2-6Piston,pistonringsandconnectingrodThepistonisanimportantpartofafour-strokecycleengine.Mostpistonsaremadefromcastaluminum.Thepiston,throughtheconnectingrod,transferstothecrankshafttheforcecreatedbytheburningfuelmixture.Thisforceturnsthecrankshaft.Towithstandtheheatofthecombustionchamber,thepistonmustbestrong.Italsomustbelight,sinceittravelsathighspeedsasitmovesupanddowninsidethecylinder.Thepistonishollow.Itisthickatthetopwhereittakesthebruntoftheheatandtheexpansionforce.Itisthinatthebottom,wherethereislessheat.Thetoppartofthepistonisthehead,orcrown.Thethinpartistheskirt.Mostpistonshavethreeringgroovesatthetop.Thesectionsbetweentheringgroovesarecalledringlands.pistonringspistonringsfitintoringgroovesnearthetopofthepiston.Insimplestterms,pistonInringsarethin,circularpiecesofmetalthatfitintogroovesinthetopsofthepistons.Inmodernengines,eachpistonhasthreerings.(Pistoninolderenginessometimeshadfourrings,orevenfive.)Theinsidesurfaceoftheringfitsinthegrooveonthepiston.Thering'soutsidesurfacepressesagainstthecylinderwalls.Ringsprovidetheneededsealbetweenthepistonandthecylinder walls.Thatis,onlytheringscontactthecylinderwalls.Thetoptworingsareto keepthegasesinthecylinderandarecalledcompressionrings.Theloweronepreventstheoilsplashedontothecylinderborefromenteringthecombustionchamber,andiscalledanoilring.ThepistonpinThepistonpinholdstogetherthepistonandtheconnectingrod.Thispinfitsintothepistonpinholesandintoaholeinthetopendoftheconnectingrod.Thetopendoftherodismuchsmallerthantheendthatfitsonthecrankshaft.Thissmallendfitsinsidethebottomofthepiston.Thepistonpinfitsthroughonesideofthepiston,throughthesmallendoftherod,andthenthroughtheothersideofthepiston.Itholdstherodfirmlyinplaceinthecenterofthepiston.Pinsaremadeofhigh-strengthsteelandhaveahollowcenter.Manypinsarechrome-platedtohelpthemwearbetter.Apistonpinfitsintoaroundholeinthepiston.Thepistonpinjoinsthepistontotheconnectingrod.Thethickpartofthepistonthatholdsthepistonpinisthepinboss.ConnectingRodsTheconnectingrodlittleendisconnectedtothepistonpin.Abushmadefromasoftmetal,suchasbronze,isusedforthisjoint.Thelowerendoftheconnectingrodfitsthecrankshaftjournal.Thisiscalledthebigend.Forthisbig-endbearing,steel-backedleadortinshellbearingsareused.Thesearethesameasthoseusedforthemainbearings.Thesplitofthebigendissometimesatanangle,sothatitissmallenoughtobewithdrawnthroughthecylinderbore.Theconnectingrodismadefromforgedalloysteel.CrankshaftsThecrankshaftisregardedasthe“backbone%ftheengine(Fig.2-7).Thecrankshaft,inconjunctionwiththeconnectingrod,convertsthereciprocatingmotionofthepistontotherotarymotionneededtodrivethevehicle.Itisusuallymadefromcar-bonsteelwhichisalloyedwithasmallproportionofnickel.Themainbearingjournalsfitintothecylinderblockandthebigendjournalsalignwiththeconnectingrods.Attherearendofthecrankshaftisattachedtheflywheel,andatthefrontendarethedrivingwheelsforthetiminggears,fan,coolingwaterandalternator.Thethrowofthecrankshaft,i.e.thedistancebetweenthemainjournalandthebigendcenters,c

ontrolsthelengthofthestroke.Thestrokeisdoublethethrow,andthestrokelengthisthedistancethatthepistontravelsfromTDCtoBDCandviceversa.Fig.2-7ThecrankshaftFlywheelTheflywheelismadefromcarbonsteel.Itfitsontotherearofthecrankshaft.Aswellaskeepingtheenginerotatingbetweenpowerstrokesitalsocarriestheclutch,whichtransmitsthedrivetothegearbox,andhasthestarterringgeararounditscircumference.Thereisonlyoneworkingstrokeinfoursoaflywheelisneededtodrivethecrankshaftduringthetimethattheengineisperformingthenon-powerstrokes.ValveSystemBearings-Fig.2-8PartsofthevalvetrainThevalveoperatingassemblyincludestheliftersorcamfoilowers,pushrods,rockerarmsandshaftsorpivot,valveandspringsetc.Thepurposeofthistoopenandclosetheintakeandexhaustportsthatleadtothecombustionchambersasrequired(Fig.28).Valvemechanismsvarydependingonthecamshaftlocation.Whenthecamshaftispositionedintheengineblock,valveliftersaremountedintheopeningsabove thecamshaft.Pushrodsareconnectedfromeachvalveliftertoapivotedrockerarmmountedaboveeachvalve.Alobeonthecamshaftispositioneddirectlybeloweachvalvelifter.Atypicalcamshaftdrive has asprocket bolted to the endofthecamshaft,andamatchingsprocketisattachedtotheendofthecrankshaft.Thosetwosprockets maybemeshed togetheror surroundeda steel chain to havethecamshaftdrive.Whenthelowerpartofthecamshaftlobeisrotatingunderthevalvelifter,thevalvespringholdsthevalveclosed.汽車發(fā)動(dòng)機(jī)1發(fā)動(dòng)機(jī)的分類和整體力學(xué)汽車發(fā)動(dòng)機(jī)可根據(jù)如下因素進(jìn)行分類：10循環(huán)系統(tǒng)，（2）冷卻系統(tǒng)，（3）燃油系統(tǒng)，（4）點(diǎn)火方式，（5）氣門布置，（6）氣缸排列，（7）發(fā)動(dòng)機(jī)轉(zhuǎn)速。用于汽車的發(fā)動(dòng)機(jī)是內(nèi)燃機(jī)。汽油在發(fā)動(dòng)機(jī)內(nèi)部燃燒，產(chǎn)生的高壓力使活塞移動(dòng)，這一運(yùn)動(dòng)通過連桿傳遞到曲軸，使它旋轉(zhuǎn)。動(dòng)力通過動(dòng)力總成傳遞到車輪，從而帶動(dòng)汽車前進(jìn)。發(fā)動(dòng)機(jī)需要四個(gè)基本系統(tǒng)來運(yùn)行（圖2-1）。柴油發(fā)動(dòng)機(jī)需要其中的三個(gè)基本系統(tǒng)來運(yùn)行。它們是燃油系統(tǒng)、點(diǎn)火系統(tǒng)（柴油除外）、潤滑系統(tǒng)和冷卻系統(tǒng)。 然而，其他三個(gè)相關(guān)系統(tǒng)也是必要的。這些是排氣系統(tǒng)，排放控制系統(tǒng)，啟動(dòng)系統(tǒng)。每個(gè)系統(tǒng)執(zhí)行一項(xiàng)基本工作，使發(fā)動(dòng)機(jī)正常運(yùn)行。

圖2-1發(fā)動(dòng)機(jī)結(jié)構(gòu)2發(fā)動(dòng)機(jī)工作原理“沖程”一詞是用來形容汽缸內(nèi)活塞的運(yùn)動(dòng)?；钊麖淖罡呶恢茫═DC,上止點(diǎn)）運(yùn)動(dòng)到其最低位置（BDC上，下止點(diǎn)）的運(yùn)動(dòng)過程被稱為一個(gè)沖程。做功周期可能需要兩個(gè)或四沖程來完成。大多數(shù)汽車發(fā)動(dòng)機(jī)為四沖程循環(huán)（圖2-2）。exhauEtvalve*BDC：Dotuieccin.g：rodstileLvanecrinlL圖exhauEtvalve*BDC：Dotuieccin.g：rodstileLvanecrinlL圖2-2發(fā)動(dòng)機(jī)簡圖在四沖程發(fā)動(dòng)機(jī)中，活塞在汽缸內(nèi)的動(dòng)作都需要完成一個(gè)完整的運(yùn)行周期。每個(gè)行程按所完成的動(dòng)作命名。分別是進(jìn)氣，壓縮，做功，和排氣（圖2-3）。進(jìn)氣沖程 壓縮沖程 做功沖程 排氣沖程圖2-3四沖程循環(huán)汽油發(fā)動(dòng)機(jī)1、 進(jìn)氣沖程進(jìn)氣沖程開始運(yùn)動(dòng)到活塞行程的頂端附近。當(dāng)活塞開始下降，排氣門完全關(guān)閉，打開進(jìn)氣門，創(chuàng)造一個(gè)真空，燃燒室里進(jìn)氣量開始增加。當(dāng)活塞下降，空氣/燃料混合物從化油器通過進(jìn)氣歧管進(jìn)入氣缸。活塞已經(jīng)開始上行后，進(jìn)氣行程結(jié)束進(jìn)氣門即將關(guān)閉。2、 壓縮行程當(dāng)活塞通過曲軸從BDC位置開始移動(dòng)，進(jìn)氣門關(guān)閉。在汽缸中活塞上面的空氣/燃料混合物被壓縮。活塞行程壓縮空氣/燃料混合物約為原體積的1/8（大約8:1的壓縮比）時(shí)，這時(shí)候活塞已經(jīng)達(dá)到TDC的八分之一。這就完成了壓縮沖程。3、 做功沖程在壓縮沖程中當(dāng)活塞到達(dá)TDC時(shí)，火花塞產(chǎn)生電火花。點(diǎn)火系統(tǒng)提供給火花塞一個(gè)高壓脈沖使產(chǎn)生火花?；鸹c(diǎn)燃（放火）空氣/燃料混合物，開始迅速燃燒，氣缸壓力增加多達(dá)3-5MPa。這壓力推動(dòng)活塞下降，并通過連桿曲軸的曲柄銷傳送到一個(gè)強(qiáng)大的沖動(dòng)。活塞上面的壓力推動(dòng)它從而使曲軸旋轉(zhuǎn)。4、 排氣沖程在動(dòng)力沖程結(jié)束時(shí)，凸輪軸打開排氣門，排氣沖程開始?；钊蛏线\(yùn)動(dòng)，氣缸內(nèi)的壓力迫使廢氣排出氣缸。在排氣沖程結(jié)束時(shí)，排氣門關(guān)閉進(jìn)氣打開，一遍又一遍地重復(fù)整個(gè)循環(huán)。3發(fā)動(dòng)機(jī)缸體和缸蓋3.1發(fā)動(dòng)機(jī)缸體

發(fā)動(dòng)機(jī)缸體是發(fā)動(dòng)機(jī)的基本框架。所有其他發(fā)動(dòng)機(jī)零部件裝進(jìn)或擰緊在缸體上。它擁有冷卻回路、潤滑油道（圖2-4），發(fā)動(dòng)機(jī)缸體，還擁有曲軸，機(jī)油底殼。除了頂置凸輪發(fā)動(dòng)機(jī)外，凸輪軸也屬于這部分。在大多數(shù)汽車中，此缸體是由灰鑄鐵和其他金屬，如鎳或銘，合金（混合物）鑄造成的。圖2-4V6發(fā)動(dòng)機(jī)缸體有些發(fā)動(dòng)機(jī)缸體，尤其是那些小型車使用鑄鋁，這種金屬比鑄鐵輕得多。然而，鐵的耐磨性比鋁好。因此，在大多數(shù)鋁制發(fā)動(dòng)機(jī)汽缸內(nèi)襯有鐵或鋼材質(zhì)的套 管。這些軸套叫做氣缸套。一些發(fā)動(dòng)機(jī)缸體完全由鋁做成。3.2氣缸套氣缸套用于發(fā)動(dòng)機(jī)缸體內(nèi)，用來防止活塞和活塞環(huán)對(duì)缸體的磨損。缸體可以由一種既輕也易于成型的金屬制成，而缸套則用來承受活塞跟活塞環(huán)的磨損。有兩種主要類型的缸套：干缸套和濕缸套（圖2-5）。干缸套濕缸套圖2-5缸套3.3缸蓋氣缸蓋是缸體的頂部，相當(dāng)于一所房子的屋頂與活塞頂部形成燃燒室。直列式輕型車輛的發(fā)動(dòng)機(jī)氣缸只有一個(gè)缸蓋；較大的直列式發(fā)動(dòng)機(jī)可以有兩個(gè)或兩個(gè)以上。正如發(fā)動(dòng)機(jī)缸體，缸蓋也可由鑄鐵或鋁合金制成。氣缸蓋攜帶閥門，氣門彈簧，搖臂軸，搖臂，推動(dòng)氣門齒輪工作的推桿。有時(shí)，凸輪軸直接安裝在缸蓋上，不用搖臂控制氣門工作。這被稱為頂置凸輪軸布置。3.4墊片缸蓋與高強(qiáng)度鋼螺栓連接缸體。缸體和頭部之間的聯(lián)合，必須不透氣，使燃燒的混合物不能泄漏。這是通過使用氣缸蓋墊片實(shí)現(xiàn)。密封墊片還可以用于連接的其他部分，如油底殼，歧管，或水泵和缸體之間。3.5油底殼油底殼通常由鋼沖壓形成。油底殼和缸體下部一同被叫做曲軸箱；它們把曲軸封閉起來。潤滑系統(tǒng)中的油泵，抽出油底殼中的油，并把它傳送到發(fā)動(dòng)機(jī)的所有工作部件。機(jī)油流出再通過管道流回油底殼。因此，機(jī)油要在發(fā)動(dòng)機(jī)的工作部件不斷地循環(huán)流動(dòng)。