专业汽车英语

专业汽车英语｛维修车必懂知识｝专业英语——EngineTerms（发动机术语）EngineTerms（发动机术语）TDC(topdeadcenter)―thepositionofthecrankandpistonwhenthepistonisfartherawayfromthecrankshaft.TDC(上止点)-当活塞离曲轴最远时，曲柄和活塞的位置。BDC(bottomdeadcenter)―thepositionofthecrankandpistonwhenthepistonisnearesttothecrankshaft.BDC(下止点)-当活塞离曲轴最近时，曲柄和活塞的位置。stroke―thedistancebetweenBDCandTDC;strokeiscontrolledbythecrankshaft.行程-下止点和上止点之间的距离；行程由曲轴控制。bore―theinternaldiameterofthecylinder.缸径-汽缸的内径。sweptvolume―thevolumebetweenTDCandBDC.有效容积-上止点和下止点之间的体积。enginecapacity―thisisthesweptvolumeofallthecylinders,e.g.afour-cylinderenginehavingacapacityoftwoliters(2000cm3)hasacylindersweptvolumeof500cm3.发动机排量-这是全部汽缸的有效容积，例如一台排量为两公升(2000cm3)的4个汽缸的发动机每一个汽缸的有效容积为500cm3。clearancevolume―thevolumeofthespaceabovethepistonwhenitisatTDC.间隙容积–当活塞位于上止点时，活塞顶上面的气缸空间。compressionratio=(sweptvol+clearancevol)/(clearancevol)压缩比=(有效容积+间隙容积)/(间隙容积)two-stroke―apowerstrokeeveryrevolutionofthecrank.二冲程–曲柄旋转一圈作功一次。four-stroke―apowerstrokeeveryotherrevolutionofthecrank.四冲程-曲柄旋转两圈作功一次。汽车专业英语——ValveSystem（配气机构）ValveSystem（配气机构）InletValveTiming（进气配气定时）IftheinletvalveopenedatTDCoftheintakestrokeandclosedatBDCofthatstroke,itwouldhaveadurationof180°.Itwouldhaveremainedopenforhalfofacomplete360°revolution,or180°.However,ittakessometimeforthevalvetoopentoitsfullposition.Italsotakestimeforittoclosetightly.ThereforethevalveisopenedbeforeTDC(BTDC)andclosedafterBDC(ABDC).如果进口门在进气行程的上止点打开并且在这次行程的下止点关闭，它将有180°的开度。气门在180°转角内完全打开。然而气门达到全开位置需要一定时间，完全关闭也需要一定时间。因此阀门在上止点(BTDC)之前被打开，在下止点(ABDC)之后关闭。ExhaustValveTiming（排气配气定时）IftheexhaustvalveopenedatBDCatthebeginningoftheexhauststrokeandclosedatTDCattheendoftheexhauststroke,itwouldhaveadurationof180°.Butliketheinletvalve,theexhaustvalveneedstimetoreachthefull-openposition,Italsoneedstimetoreachthefull-closedposition.SotheexhaustvalveopensbeforeBDCandclosesafterTDC.如果排气门在排气行程的下止点打开并且在这次行程的上止点关闭，它将有180°的持续。但是像进气门一样，排气门需要时间到达充分打开和关闭的位置。因此排气门在下止点之前打开，在上止点之后关闭。ValveOverlap（气门重叠）Theintakeopensat17°BTDCandtheexhaustclosesat17°ATDC.Thus,foraperiodof34°,bothofthevalvesareopen:(17°+17°=34°).Thisperiodoftimeisknownasvalveoverlap.Theclosingoftheexhaustvalvelapsovertheopeningoftheintakevalve.Duringthistime,thefirstofthenewmixturepushesthelastoftheburnedgasesouttheexhaustvalve.Valveoverlapisheldtoaminimumonturbo-chargedengines.Thispreventstheintakechargefrombeingblownouttheexhaust.进气门在上止点前17°打开，排气门在上止点后17°关闭。因此，有34°的一段时期，两个阀门都是开的：(17°+17°=34°)。这时期被称为气门重叠。排气门的关闭和进气门的开启重叠。在这个时候，新的混合气推动燃烧后的废气从排气门排出。在涡轮增压发动机上气门重叠角被保持在一个最小值。这就防止废气倒流入进气管。ValveOperation（配气机构）Tocoordinatethefour-strokecycle,agroupofpartscalledthevalvetrainopensandclosesthevalves(movesthemdownandup,respectively).Thesevalvemovementsmusttakeplaceatexactlytherightmoments.Theopeningofeachvalveiscontrolledbyacamshaft.那些打开和关闭气门的气门传动是为了协调四冲程的工作循环(使他们各自上下移动)。这些阀门运动必须正好在合适的时刻进行。每个阀门的开启由凸轮轴带动Overheadcamshaft(OHC)valvetrain（顶置凸轮轴气阀传动）Thecamisanegg-shapedpieceofmetalonashaftthatrotatesincoordinationwiththecrankshaft.Themetalshaft,calledthecamshaft,typicallyhasindividualcamsforeachvalveintheengine.Asthecamshaftrotates,thelobe,orhighspotofthecam,pushesagainstpartsconnectedtothestemofthevalve.Thisactionforcesthevalvetomovedownward.Thisactioncouldopenaninletvalveforanintakestroke,oropenanexhaustvalveforanexhauststroke.凸轮是一在轴上的蛋形的金属，通过曲轴协调旋转。那金属轴叫凸轮轴，在发动机里的每个气门一般有各自的凸轮。当凸轮轴旋转时，凸轮凸起的或者高点的位置，推动气门座。这行动强迫阀门向下移动。这过程能使进气门在进气行程打开，或者排气门在排气行程打开。Asthecamshaftcontinuestorotate,thehighspotmoveswayfromthevalvemechanism.Asthisoccurs,valvespringspullthevalvetightlyclosedagainstitsopening,calledthevalveseat.因为凸轮轴继续旋转，凸轮轴上的凸起部分离开气门装置。当这发生时，气门弹簧紧紧地关闭气门口，叫做气门座。Valvesinmoderncarenginesarelocatedinthecylinderheadatthetopoftheengine.Thisisknownasanoverheadvalve(OHV)configuration.Inaddition,whenthecamshaftislocatedoverthecylinderhead,thearrangementisknownasanoverheadcamshaft(OHC)design.Somehigh-performanceengineshavetwoseparatecamshafts,oneforeachsetofinletandexhaustvalves.Theseenginesareknownasdualoverheadcamshaft(DOHC)engines.现代汽车发动机里的阀门位于发动机顶上的汽缸盖。这被称为顶置气门(OHV)结构。另外，当凸轮轴位于汽缸盖上面时，这种方式被称为是顶置凸轮轴(OHC)结构。一些高性能发动机有两个单独的凸轮轴，分别负责开关进气门和排气门。这些发动机被称为双顶置凸轮轴(DOHC)发动机。Push-rodvalvetrain（推杆气阀传动）Thecamshaftalsocanbelocatedinthelowerpartoftheengine,withintheengineblock.Totransferthemotionofthecamupwardtothevalve,additionalpartsareneeded.凸轮轴也装在发动机底部的气缸体内。为了将凸轮的运动传给气门需要一些附属装置。Inthisarrangement,thecamlobespushagainstroundmetalcylinderscalledcamfollower.Asthelobeofthecamcomesupunderthecamfollower,itpushesthecamfollowerupward(awayfromthecamshaft).Thecamfollowerridesagainstapushrod,whichpushesagainstarockerarm.Therockerarmpivotsonashaftthroughitscenter.Asonesideoftherockerarmmovesup,theothersidemovesdown,justlikeaseesaw.Thedownward-movingsideoftherockerarmpushesonthevalvestemtoopenthevalve.在这种布置中，凸轮凸角推动凸轮挺杆。当凸轮的凸角在凸轮挺杆下出现时，它推动凸轮挺杆向上运动(离开凸轮轴)。凸轮挺杆推动控制摇臂的推杆。摇臂以通过它的中心为轴而旋转。当摇臂的一侧上升，其另一侧下降，正如一块跷跷板一样。摇臂向下移动的那一边推动气门杆以打开气门。Becauseapush-rodvalvetrainhasadditionalparts,itismoredifficulttorunathighspeeds.Push-rodenginestypicallyrunatslowerspeedsand,consequently,producelesshorsepowerthanoverhead-camshaft