汽车专业英语(原书作者宋红英)第一～二章ppt课件

UnitoneAutomobileStructure,.,Contents,Pre-questions,II.TextExplanation,III.Exercises,.,TypesofModernAutomobiles1）cars2）passengercars3）trucks4）tractorsandvehiclecombination5）specialtypevehicle6）Self-dumpingcar7）farmvehicle8)off-roadvehicle,Pre-questions,.,Specialvehicle,car,Tractor,Truck,PassengerCars,.,2、withrespecttoenginearrangementanddrivingtype,Pre-questions,.,Doyouknowwhobuiltthefirstcarintheworldandwhen?KarlBenzIn1886,Pre-questions,.,Howmanymainpartsdoestheautomobileconsistof?,1-engine,2-chassis,3-body,4-electricalsystem,Pre-questions,.,Whichiscalledthe“heart”ofautomobile?AnenginethatisusedtosupplypowerforanautomobileWhatisthechassiscomposedof?drivingsystem,runninggear,steeringsystemandbrakesystem.,Pre-questions,.,Drivingsystem,Brakesystem,Steeringsystem,runninggear,Pre-questions,.,Whatistheelectricalsystemcomposedof?Theelectricsystemincludesthebattery,generator,startingsystem,ignitionsystem,lightingsystem,hornsystem,radioandotherdevices.,Pre-questions,.,Whatarethefunctionsofthefoursystems?Drivingsystemworksbytransmittingenginepowertothedrivingwheels.Suspensionsystemsfunctionistoincreasestrengthanddurabilityofcomponentsandtomeetcustomersrequirementsforridingcomfortanddrivingsafety.Steeringsystemisusedtocontrolthedrivingdirectionofanautomobile.Brakesystemisusedtoretardthemotionofthevehicle.,Pre-questions,.,Inotherwords,anyautomobileiscomposedofthesectionssuchasengine,chassis,bodyandelectricsystem.Inotherwords换句话说becomposedof由.组成译文：换句话说，任何一辆汽车都是由发动机、底盘、车身和电器设备组成的。,II.TextExplanation,.,InotherwordsInotherwords,theyremainrelativelyconstantorstatic.换句话说，它们相对的稳定、静止。Inotherwords,wehaveadheredtoscientificsocialism.也就是说，我们坚持了科学社会主义。becomposedofNavymustbecomposedofsurfaceshipunitandsubmarineunit.海军一定是由水面舰艇部队和潜艇部队组成。,II.TextExplanation,.,Theinternalcombustionengineburnsfuelwithinthecylindersandconvertstheexpandingforceofthecombustionor“explosion”intorotaryforceusedtopropelthevehicle.Theinternalcombustionengine内燃机Co.使转变,转换.Propelvt.推进,驱使译文：内燃机在汽缸内燃烧燃料，然后把燃烧或者“爆炸”所产生的膨胀力变成旋转力，用以推动车辆前进。,II.TextExplanation,.,Co.Theyconvertedthegarageintoatheater.他们将车库改成戏院。convertwaterintoice.将水变成冰convertingfeetintometers.将英尺换算成公尺,II.TextExplanation,.,Brakesystemisabalancedsetofmechanicalandhydraulicdevicesusedtoretardthemotionofthevehiclebymeansoffriction.Hydraulichaidrlikadj.液压的,水力的Retardritdvt.延迟,使减速,阻碍Frictionfriknn.摩擦,摩擦力译文：制动系统是一套平衡的机械和液压设备，它可通过摩擦来阻止车辆的运动。,II.TextExplanation,.,bymeansof用.方式（方法），依靠Theysucceededbymeansofperseverance.他们依靠坚忍不拔而获得成功。Healwaysgoestoschoolbymeansofbike他总是骑自行车上学,II.TextExplanation,.,II.TextExplanation,In1956,theNo.1AutoPlantwasestablishedinChangchun,andturnedoutthefirstbatchofliberationautomobilesforourcountry.establishvt.建立,设立,确定turnedoutvt.生产,起床,翻出,制造,关掉译文：在1956年，一汽在长春成立了，并且为我们国家生产出了第一批解放牌轿车。,.,turnoutAvastcrowdturnedouttowatchthematch.大群的观众到场观看比赛。Ifthedayturnsoutwetwemayhavetochangeourplans.万一下雨的话，我们也许得改变计划。,II.TextExplanation,.,III.Exercises,TranslatethefollowingexpressionsintoChinese.chassisdrivingsysteminternalcombustionenginesteeringsystembrakingsystemclutchgearboxuniversaljointpropellershaftgenerator,底盘传动系统内燃机转向系统制动系统离合器变速箱万向节驱动轴发电机,.,IdentifytheEnglishnamesofclutchaccordingtothepicture.,III.Exercises,1-engine;2-clutch;3-gearbox;4-propellershaft;5-differential;6-rearaxle,.,Themotorvehicleengineisbasicallyadeviceforconvertingtheinternalenergystoredinitsfuelintomechanicalenergy.Itisclassifiedasaninternalcombustionenginebyvirtueofthisenergyconversiontakingplacewithintheenginecylinders.Sincetheterm”energy”impliesthecapacitytoperformwork,theengineisthusabletopropelthevehiclealongtheroadand,withinlimits,overcomeunwantedoppositiontoitsmotionarisingfromrollingfrictionandairdrag.Tofacilitatethisprocesstheengineiscombinedwithatransmissionsystem.,III.Exercises,.,I.TranslatethefollowingsentencesintoChinese.Ineffect,thedrivingsystemworksbytransmittingenginepowertothedrivingwheels.实际上，传动系统的作用是将发动机的动力传递到驱动车轮。Theelectricsystemsupplieslightinganddrivingpowerfortheautomobile.电气系统可为汽车提供照明和驱动的电力。Thebodystylingprovidesanattractive,colorful,modernappearanceforthevehicle.车身的式样为汽车提供了诱人的，多彩的，现代的外观形象。,III.Exercises,.,汽车主要由四个部分组成，他们是：发动机、底盘、车身和电气设备。Anautomobileisgenerallycomposedoffoursectionssuchasengine,chassis,bodyandelectricalsystem.传动系由离合器、变速箱、传动轴、后桥、差速器、从动轮组成。Thetransmissionsystemconsistsofclutch,gearbox,propellershaft,rearaxle,differentialandthedrivingroadwheels.。,III.Exercises,II.TranslatethefollowingsentencesintoEnglish.,.,气门机构的作用是及时地吸入新鲜的混合气和排出废气Thevalvegearprovidestimelyadmissionofthefreshchargeintothecylindersandexhaustofspentgasesfromthem.,III.Exercises,ThankYou!,Unit2-1MainComponentsofEngine,.,Contents,Pre-questions,II.TextExplanation,III.Exercises,.,Pre-questions,Theheartofautomobile,.,Whatimpressionoftheengine?,complicated,power,Pre-questions,.,Whataretheretypesoftheengine?electricmotors,steamengines,andinternalcombustionenginesWhatstheinternalcombustionengine?burnsfuelwithinthecylindersandconvertstheexpandingforceofthecombustionintorotaryforceusedtopropelthevehicle.,Pre-questions,.,Single-cylinderengine,cylinder,piston,Pistonpin,Connectingrod,crankshaft,Oilpipe,Intakevalve,Exhaustvalve,Timinggear,Oilpump,.,whatisthepowersourceofautomobileandhowtoproduce?,piston,pistonpin,connectingrod,crankshaft,EnginePowerisproducedbythelinearmotionofapistoninacylinder.Theconnectingrodtransmitstheup-and-downmotionofthepistontothecrankshaft,whichchangesitintorotarymotion.,Pre-questions,.,Theenginecomprisestwomechanismandfivesystems,whatarethey?crankshaftandconnectingrodmechanism,valvegear,coolingsystem,lubricatingsystem,fuelsystem,startingsystem,ignitionsystem,Pre-questions,.,connectingrod,flywheel,crankshaft,piston,intakevalve,exhaustvalve,pushrod,tappet,timinggears,ValvegearConnectingrod,.,Enginecoolingsystem,.,Enginelubricatingsystem,.,Fuelsupplysystem,.,Valvegear,.,Whatsthefunctionofthecrankshaftandconnectingrodmechanism?Itsfunctionistoconvertheatenergyintomechanicalenergyusedtodrivethevehicles.,Pre-questions,.,Theinternalcombustionengine,asitsnameindicates,burnsfuelwithinthecylindersandconvertstheexpandingforceofthecombustionintorotaryforceusedtopropelthevehicle.译文：内燃机，顾名思义，就是燃料在气缸内部燃烧，并且把燃烧时的膨胀力转化为驱动车辆的旋转力。,II.TextExplanation,.,Ofallautomobilecomponents,plicatedkmplikeitidadj.复杂的,难解的dominancedmnnsn.优势,统治译文：汽车发动机是一切汽车部件中结构最复杂，对汽车功能起支配作用的一个总成。,II.TextExplanation,.,Itsfunctionistoconvertheatenergyintomechanicalenergyusedtodrivethevehicles.Convertinto.转变；变换译文：它的作用就是将热能转换成机械能用来驱动汽车。,II.TextExplanation,.,Co.转变；变换Thatbuildinghasbeenconvertedintoaschool.那座楼房改成学校了。兑换IwanttoconvertsomeHongKongdollarsintoAmericandollars.我想把一些港元换成美元。改变信仰、党派或意见等Shemanagedtoconverthimtoheropinion.她终于设法说服了他接受她的意见。,II.TextExplanation,.,Powerisproducedbythelinearmotionofapistoninacylinder.linearliniadj.线的,直线的,线性的pistonpistnn.活塞,II.TextExplanation,.,Thepistonattachedtothetopofaconnectingrodbyapin,calledapistonpinorwristpin.attachtov.连接connectingrod连杆pistonpin=wristpin活塞销,II.TextExplanation,.,Theconnectingrodtransmitstheup-and-downmotionofthepistontothecrankshaft,whichchangesitintorotarymotion.transmitto把传到whichchangesitintorotarymotion定语从句,II.TextExplanation,.,dieselengineswaterpumptheignitiondistributoroilpantiminggearcrankshaftandconnectingrodmechanismvalvegearfuelsystemexhaustpipeexhaustmanifold,III.Exercises,TranslatethefollowingexpressionsintoChinese.,柴油发动机水泵分电器油底壳正时齿轮曲柄连杆机构配气机构燃油系统排气管排气歧管,.,1-cylinderheadcover2-piston3-timingtoothedbelt4-waterpump5-oilpan6-oilpump7-crankshaft8-flywheel9-distributor10-valve,III.Exercises,.,Thecrankshaftrepresentsthefinallinkintheconversionofreciprocatingmotionatthepistontooneofrotationattheflywheel.Inthecastofthemulti-cylinderengine,thecrankshafthastocontroltherelativemotionsofthepistons,whilereceivingtheirownimpulses.Aone-piececonstructionismostcommonlyusedforthemotor-vehiclecrankshaft,whichextendsthewholelengthoftheengineandmustthereforepossessconsiderablerigidity.,III.Exercises,.,Thetiming-drivefortheenginevalvemechanismistakenfromthefrontendofthecrankshaftasisthepulleyandbeltdrivefortheengineauxiliaries,suchasthecoolingfanandthealternatorforelectricalsystem.attachedtotherearendofthecrankshaftistheengineflywheel.,III.Exercises,.,I.TranslatethefollowingsentencesintoChinese.1Engineisthepowersourceoftheautomobile.Powerisproducedbythelinearmotionofapistoninacylinder.发动机是汽车的动力源.它通过汽缸内的活塞线性运动产生的.2Thefuelsystemworksaccordingtotherequirementsoftheengineasitprovidesanair-fuelmixturewhichmustbeinproportiontothespeedandloadplacedontheengine.燃油系统的作用是根据发动机的转速和负荷提供一定比例的可燃混合气以满足发动机的需求。,III.Exercises,.,3Thevalvegearprovidestimelyadmissionofthefreshchargeintothecylindersandexhaustofspentgasesfromthem.配气机构机构可定时的将新鲜气体充入气缸，并且将废气排放出去。,III.Exercises,.,1发动机主要有两大机构五大系统组成。Anengineismainlycomposedoftwomechanismsandfivesystems.2曲柄连杆机构主要包括机体组，活塞连杆组和曲轴飞轮组。Thecrankshaftandconnectingrodmechanismmainlyconsistsoftheenginecrankcaseandcylinderblock,thepistonandconnectingrod,thecrankshaftandflywheel.,III.Exercises,II.TranslatethefollowingsentencesintoEnglish.,.,3水泵工作时，可以将冷却液在发动机水套中和散热器之间来回流动。Whenrevolving,thewaterpumpcirculatescoolantbetweentheenginewaterjacketsandtheradiator.,III.Exercises,.,III.Exercises,PrincipleofFour-strokeEngine,1、intakestroke2、compressstroke3、powerstroke4、exhauststroke,Intakevalve,Exhaustvalve,ThankYou!,Unit2-2CylinderBlockandCylinderHead,.,Contents,Pre-questions,II.TextExplanation,III.Exercises,.,EngineBody,crankcase,cylinderblock,cylinderhead,cylinder,oilpassageandwaterpassage,oilpan,Thecylindergasket,.,Whatistheengineblockcomprisedof?thecylindersectionandthecrankcasesection,Pre-questions,thecylinder,crankcase,.,Pre-questions,Howmanytypeshastheenginearrangement,whatarethey?,In-line,V-type,Horizontallyopposedtype,.,Whatsthefunctionandthematerialofthecylinderhead?Function：SealthetopthecylinderandformthecombustionchamberwiththepistonandthecylinderMaterial:greyironoralloyironaluminum,Pre-questions,.,cylindergasket,cylinderhead,cylindercover,pad,tofitsparkplug,Pre-questions,.,Whattypesofthecombustionchambersarethere?,Pre-questions,wedge-shapedbasin-shapedhemispherical,.,Theengineblockisthemainsupportingstructuretowhichallotherpartsareattacheddirectlyorindirectly.attachedtttvt附上.的directlyadv.直接地Indirectlyadv.间接地译文：气缸体是主要的支承部件，它可以将其它部件直接或间接的装配在上面。,II.TextExplanation,反义词,.,Thesurfacesaremachinedtoallowthepistonstomovewithminimumwearandfriction.allowvt允许，承认allowsb.todosth.allowdoingsth.Frictionfriknn.摩擦,摩擦力译文：加工出的表面允许活塞在最小磨损和摩擦力下运动。,II.TextExplanation,.,Allow使成为可能，允许近义词：permitThewindfallallowedmetobuyahouse.这意外之财使我得以购置一幢房子。Allowmetointroducemyself.请允许我自我介绍一下。,II.TextExplanation,.,Withtheincreasedconcernforprovidinghigheroutputandlowerfuelconsumption,carmanufacturesaretryingtomakethevehiclelighter.Concernvt.涉及,关系到n.关心,关注concernfor对.的关心/忧虑concernwith和.有关（一般用.+beconcernedwith.）consumptionn.消费,消费量译文：随着对汽车产量和低燃耗的关注度越来越高，汽车生产厂家尽量把汽车做的轻一些。,II.TextExplanation,.,Concernvt.1.(不用被动语态)关于2.涉及,关系到;影响到Theletterischieflyconcernedwithexportcommodities.这封信主要是关于出口商品的。Thenewsconcernsyourbrother.这消息与你兄弟有关。3.使担心;使不安(+about/for)Theboyspoorhealthconcernedhisparents.那男孩健康状况不佳,使他的父母亲忧虑。Heisconcernedforhersafety.他担心她的安全。4.使关心(+about/with)Hewasveryconcernedabouther.他对她非常关心。,II.TextExplanation,.,Itshouldbepaidattentiontothedirectionwhenfixing.to是介词,所以后面接名词以及动名词.payattentiontosth./doingsth.Pleasepayattentiontotakingcareofyourbaby.请注意照顾好你的小孩.译文：应该注意装配时的方向。,II.TextExplanation,.,Cylindergasket,Function：fittedbetweenthecylinderblockandcylinderheadtosealtheareabetweenthemandpreventleakageofgas,oilandwater.Payattentiontothedirectionwhenfixing,II.TextExplanation,.,Inordertomakethealuminumstrongerandlesslikelytowarp,certainmaterialsareaddedtothemetalorasteellinerplacedintheblock.Inorderto为了Westartedearlyinordertoarrivebeforedark.为了在天黑前到达,我们很早就动身了。,II.TextExplanation,.,warpw:pn.弯曲,歪曲vt.弄歪,使翘曲vi.变弯,变歪addedtoincresed（本身）增加addedto(别人，别的东西)增加译文：为了使铝制材料强度更高，尽可能的减少弯曲变形，可加入一定的金属材料或者在缸体内镶钢缸套。,区别,II.TextExplanation,.,cylinderblockcylinderheadoilpancylindergasketcylinderlinerwedge-shapedcombustionchamberbasin-shapedcombustionchamberin-lineenginessparkplugsinjection,III.Exercises,TranslatethefollowingexpressionsintoChinese.,气缸体气缸盖油底壳气缸垫缸套楔形燃烧室盆形燃烧室直列发动机火花塞喷油器,.,III.Exercises,1-cylinderheadcover;2-cylinderhead;3-cylindergasket;4-cylinderblock;5-oilpan,.,Ithaslongsincebeenestablishedpracticetocombinethecylinderblockandcrankcaseintoasingleunit,thisgenerallybeingtermed“monobloc”construction.Thehistoricaloriginsofthisformofconstructiondatebacktotheearly1920s,whentherewasageneraltrendtowardssimplificationoftheenginestructure.,III.Exercises,.,Untilthenthecylinderblockandcrankcasewereproducedasseparateunits,incastironandaluminumalloyrespectively,andthenboltedtogether.Inrelationtomodernenginedesign,themonoblocconstructionprovidesaverynecessaryrigidfoundationfortheengineandreducesmanufacturingcosts.,III.Exercises,.,I.TranslatethefollowingsentencesintoChinese.1Inordertomakethealuminumstrongerandlesslikelytowarp,certainmaterialsareaddedtothemetalorasteellinerplacedintheblock.为了使铝制缸体刚度更强和尽可能的减少磨损，可将一些材料加入其中或者在缸体中安装缸套。2Thecylindergasketsfunctionistosealtheareabetweenthemandpreventleakageofgas,oilandwater.气缸垫的作用就是密封缸盖与缸体之间的区域，避免漏气、漏油和漏水。,III.Exercises,.,3Thecylindersofmulti-cylinderautomotiveenginesarearrangedinoneofthreeways.多缸发动机的气缸排列方式是这三种形式之一。,III.Exercises,.,II.TranslatethefollowingsentencesintoEnglish.1气缸垫安装时，要注意它的方向性。Itshouldbepaidattentiontothedirectionwhenfixingthecylindergasket.2铝制缸体为了提高它的刚度，常常要在气缸中安装缸套。Inordertomakethealuminumstronger,asteellineroftenplacedintheblock.3直列式是发动机中最简单的一种排列方式。In-lineengineisthesimplestarrangement.,III.Exercises,ThankYou!,Unit2-3PistonandConnectingRod,.,Contents,Pre-questions,II.TextExplanation,III.Exercises,.,whatdoesthepistonassemblyconsistof?Itmainlyconsistsofpiston,pistonrings,pistonpin,andconnectingrod.,Pre-questions,.,piston,pistonrings,pistonpin,connectingrod,Pre-questions,piston,pistonrings,pistonpin,connectingrod,Function?,.,Function:transmittheforceofexpansiontocrankshaftthroughconnectingrodWithstandinggaspressure,Pre-questions,characteristic,light,rigid,cylindricalshapedhollow,.,Pre-questions,cylindricalshapedhollow,.,Whatisthepistoncomposedof?pistonhead,pistonlands,pistonskirtandpistonpinhole.,Pre-questions,.,Components,pistontop,pistonhead,pistonskirt,pistonpinhole,Pre-questions,.,Whatsthefunctionoftheconnectingrod?topassthereciprocatingpowerofthepistontothecrankshaft.,Pre-questions,Smallend,Connectingrodbushing,Connectingrod,Bigend,Connectingrodhalfshells,Connectingrodcap,.,Towithstandtheheatofthecombustionchamber,thepistonmustbestrong.Withstandvt.抵挡，经受住thecombustionchamber燃烧室译文：活塞必须要坚固才能承受燃烧室的热量。,II.TextExplanation,.,Insomeapplication,anarrowgrooveiscutintothepistonabovethetopringtoserveasa“heatdam”toreducetheamountofheatreachingthetopring.groovegrvn.凹槽heatdam隔热槽译文：在有些结构中，为了减少传到顶部活塞环的热量，在活塞环的上部切割出一个很窄的环槽，叫做“隔热槽”。,II.TextExplanation,.,cutintov减少，侵犯,打断Dontcutintothestory.不要打断故事。Theknifeeasilycutintothecake.刀一下子就切进了蛋糕。Theotherhousegotoldandshabby,andthatcutintothevalue.周围的房子都破旧不堪,这使得他房子的价值降低了。,II.TextExplanation,.,serveasvt.担任(充当,起.的作用)Thesephilosophicalviewsserveasaguideinlife.这些哲学观点可以作为处世指南。Hewillserveasmayor他将任市长一职。近义词：actas.区别：serve为服务,II.TextExplanation,.,Itmaybeflat,concave,andconvexoranyoneofagreatvarietyofshapestopromoteturbulenceorhelpcontrolcombustion.concaveknkeivn.凹,凹面convexknveksadj.表面弯曲如球的外侧,凸起的译文：（活塞顶部）形状可以是平顶、凹顶、凸顶或者其它各种形状，这些形状促进紊流或有助于控制燃烧。,II.TextExplanation,.,agreatvarietyofadj.多种,各种,多种多样的Wewillappealtoagreatvarietyofsourcesofinformation.我们将求助于多种资料来源。,II.TextExplanation,.,Classificationofpistontop,.,Toavoidmisplacingtherodcapsduringassembly,theconnectingrodsandtheirmatingcapsaremarkedononesidewithserialnumbers,startingwiththefirstrodfromtheradiator,toidentifytheirlocationintheengine.译文：为了避免装配错误，从散热器的一侧为开始，在连杆以及与其相配的连杆盖的一侧标注有序列数以区分它们在发动机中的位置。,II.TextExplanation,.,avoidvt.避免(n./+v-ing)Theyallavoidedmentioningthatname.他们都避免提及那名字。Shebrakedsuddenlyandavoidedanaccident.她紧急刹车,避免了一场车祸。theradiatorn.散热器misplacemispleisvt.放错地方,II.TextExplanation,.,TranslatethefollowingexpressionsintoChinese.pistonringpistonpinconnectingrodexpansionforcecylinderwallinthebottomofthegroovespassthereciprocatingpowerofthepistonconnectingrodsmallendconnectingrodcapconnectingrodbearinghalfshells,III.Exercises,活塞环活塞销连杆膨胀力汽缸壁在槽的底部传递活塞的往复动力连杆小头连杆盖连杆轴瓦,.,compressionrings,oilrings,pistonpin,piston,connectingrod,connectingrodbolt,crankbearinghalfshell,connectingrodcap,III.Exercises,.,Pistonringsareoftwobasictypes,thatis,compressionringsandoil-controlrings.Theyperformimportantfunctionsasfollows:theuppercompressionringsmustmaintainaneffectivesealagainstcombustiongasesleakingpastthepistonsintothecrankcase.Theloweroil-controlringsservetocontrolandeffectivelydistributethelubricatingoilthrownontothecylinderwalls,consistentwithmaintaininggoodlubricationandanacceptableoilconsumption.Theseringsalsoprovideameansbywhichsurplusheatistransmittedfromthepistontothecylinderwallandthentothecoolingjacket.,III.Exercises,.,I.TranslatethefollowingsentencesintoChinese.1Thepistonconvertsthepotentialenergyofthefuelintokineticenergythatturnsthecrankshaft.活塞将燃料燃烧的能量转换成驱动曲轴旋转的动能。2Thepistonandrodassemblytransmitsthepowerfromcombustionchambertothecrankshaft.活塞连杆组将燃烧室的能量传递给曲轴。3ShankoftheconnectingrodisprovidedwithanI-crosssectiontogivetherodmaximumrigiditywiththeminimumofweight.为了使连杆得到最大的刚度和最小的重量，连杆杆身部分加工为工形结构。,III.Exercises,.,II.TranslatethefollowingsentencesintoEnglish.1活塞销装在活塞的环形的孔里。活塞销把活塞和连杆连接起来。用来支撑活塞销的活塞厚的部分称为活塞销凸台。Apistonpinfitsintoaroundholeinthepiston.Thepistonpinjoinsthepistontotheconnectingrod.Thethickpartofthepistonthatholdsthepistonpinisthepinboss.2活塞销贯穿活塞，把连杆小头与活塞连在一起，并将连杆保持在活塞中心的适当位置处。Thepistonpinfitsthroughonesideofthepiston,throughthesmallendoftherod,andthenthroughtheothersideofthepiston.Itholdstherodfirmlyinplaceinthecenterofthepiston.,III.Exercises,.,3顶部的两道保证活塞与气缸壁间密封的环叫做气环。底下的一道防止机油飞溅到缸筒从而窜入燃烧室的环叫做油环。Thetoptworingsaretokeepthegasesinthecylinderandarecalledcompress