(新版)汽车专业英语课件：Engine components

Project3Enginecomponents12

掌握发动机的总体结构、工作原理、基本术语，分类

掌握常用术语的表达方法,了解相关其它专业术语知识目标能读懂发动机工作原理相关英文材料,能熟记相关专业词汇能读懂发动机总体构造和分类的英文材料，能熟练掌握发动机基本术语和概念的英语表达方式能对发动机各机构和系统组成中的常见零部件的英语表达准确识别能熟记常见的发动机专业术语

缩写形式能看图写出零件名称能力目标

Project3Enginecomponents3Task1

EnginePrinciplesandStructure

1.Newwordsandexpressions知识准备principle

[ˈprinsəpl]n.原则，原理convert

[kənˈvə:t,ˈkɔnvə:t]v.(使)转变(化)combustion[kəm'bʌstʃən]n.燃烧gasoline['ɡæsəli:n]n.汽油stroke[strəuk]

n.冲程spark[spɑ:k]n.火花;火星；vi.发出火星;发出闪光compress[kəmˈprɛs]vt.压紧,压缩cylinder[ˈsɪləndɚ]n.圆筒,圆柱,圆柱体,汽缸,泵体plug[plʌɡ]n.插头,插座；塞子,栓diesel

[ˈdizəl,-səl]

n.柴油；柴油机机车(或船等),内燃机车inject[ɪnˈdʒɛkt]vt.给…注射（药物等）,给…注射（液体）高职高专41.Newwordsandexpressionssufficiently[səˈfɪʃəntlɪ]adv.足够地,充分地ignite[ɪɡˈnaɪt]vt.点燃;引发,（使）燃烧,着火piston['pɪstn]n.〈机〉活塞cycle['saikl]n.循环,周期,自行车inlet[‘inlet]n.

进口，入口exhaust[iɡ'zɔ:st]vt.用尽；使非常疲倦;n.排气装置,排气管[孔]；废气valve[vælv]n.阀,活门,阀门,气门suction['sʌkʃən]n.吸,抽吸revolution[,revə'lu:ʃən]n.革命；彻底改变,重大变革；旋转;运行,公转induction[ɪn'dʌkʃən]n.就职,入伍；吸入；(电或磁的)感应；归纳(法),吸入propel

[prəˈpel]vt.推进，推动block[blɔk]n.街区,街段；大块(木料、石料、金属、冰等)；知识准备5知识目rod[rɔd]n.竿,杆,棒part[pɑ:t]n.一部分;局部；零件；角色component[kəm'pəunənt]n.成分,组成部分,部件,元件circular['sə:kjulə]adj.圆形的,环形的;循环的n.通知,通告gas-tight气密的，不透气的swivel['swɪvəl]n.转节,转环;旋轴;旋转接头vt.&vi.(使)旋转;在枢轴上转动gudgeon['ɡʌdʒən]n.易骗的人;舵钮;舵栓pin[pin]n.大头针,别针；饰针；锁,钉,插头,闩；腿coupling['kʌpliŋ]n.连接；连接器;(尤指列车等的)车钩,挂钩formula

[ˈfɔ:mjulə]n.原则，方案；公式，方程式；配方bearing['bɛəriŋ]n.举止,风度；方向；轴承offset['ɔfset]vt.抵消,补偿;adj.偏（离中）心的，抵消的crankcase['kræŋkkeis]n.曲轴箱知识准备6知识目gasket['ɡæskit]n.束帆索,垫圈,衬垫pump[pʌmp]n.泵,打气筒vt.&vi.用抽水机汲水;给…打气pulley['pʊli:]n.滑轮(组);滑车；皮带轮drain[drein]vt.&vi.(使)流干,(使)逐渐流走;n.排水沟,排水管bolt[bəult]n.螺栓；(门或窗)插销,闩;crush[krʌʃ]vt.&vi.压碎,压坏;vi.挤进,挤入ring[riŋ]n.戒指,指环；环状物,圆圈；团伙,帮派；铃声；打电话；特性grommet['ɡrɔmit]n.金属扣眼,索环distributor[dɪ'strɪbjətə]n.批发公司;批发商；(汽车上的)配电器filter['filtə]n.过滤,过滤器vt..透过,过滤vi.(消息等)走漏manifold['mænə,fəʊld]adj.多种多样的;n.具有多种形式的东西；多支管volume['vɔlju:m]n.卷,册,书卷；体积;容积,容量；音量,响度知识准备7知识目radius['reidjəs]n.半径(距离)；用半径度量的圆形面积;半径范围diameter[dai'æmitə]n.直径；放大率displacement[dɪs'pleɪsmənt]n.移置,代替;排量torque[tɔrk]n.扭矩clearance['kliərəns]n.净空,余隙；许可,批准self-contained自给的internalcombustionengine内燃机sparkplug火花塞resultin导致，致使，引起知识准备8知识目consistof由…组成upanddown上上下下connectingrod连杆fuelsystem燃油供给系ignitionsystem点火系coolingsystem冷却系lubricationsystem.润滑系TopDeadCenter(TDC)上止点BottomDeadCenter(TDC)下止点displacementvolume排量compressionratio压缩比sweptvolume工作容积clearancevolume燃烧室容积知识准备9Engineworkingprinciples任务实施Theengineisaself-containedpowerunitwhichconvertstheheatenergyoffuelintomechanicalenergyformovingthevehicle.Inbrief,theburningofthefuelcausesarapidriseincylinderpressurewhichisconvertedtousefulmechanicalenergybythepistonandthecrankshaft.Themajorityofenginesinautomobiletodayarefour-stroke,spark-ignitioninternalcombustionengines.InpetrolEngine,theair-fuelmixtureafterbeingcompressedintheenginecylindertoahighpressureisignitedbyanelectricsparkfromasparkplug.Indieselengine,dieselisinjectedintotheenginecylindercontainingaircompressedtoaveryhighpressure.Theairtemperatureissufficientlyhightoignitethefuel.Thatiswhythereisnosparkplugusedindieselengine.10Engineworkingprinciples任务实施Thefour-strokecycle(Figure3.1.1)forapetrolengine(sparkignition)isverysimilarinprincipletothatofadieselengine(compressionignitionorCI).Tocompletethecycle,fourstrokesofthepistonareneeded.StartingwiththepistonatTDC,asthecrankshaftrotates,thenextfourstrokesofthepistonwillresultinanumberofdifferentprocessesandactionstakingplace.Suctionstroke

Whenthepistonmovesdownthecylinder,theinletportisopenandtheexhaustportisclosed,afreshchargeisdrawnintothecylinder.Mostpetrolenginesdrawinamixtureofairandfuel,howeveradieselenginedrawsinachargeofaironly.Attheendofthestroke,theinletcloses.11Engineworkingprinciples任务实施12Engineworkingprinciples任务实施CompressionstrokeThenthepistonmovesbackuptocompressthisair-fuelmixture.Thecompressionforcesthefuelintoclosercombinationwithair.Justalittlebeforetheendofcompressionstroke,themixtureisignitedbyasparkproducedbysparkplug.Duringthisstrokesuctionandexhaustvalveremainclosed.Whenthemixtureinsidethecylinderiscompressed,pressureandtemperatureriseatthesametime.Powerstroke

Whenthepistonreachesthetopofitsstroke,thesparkplugemitsasparktoignitethegasoline.Thegasolinechargeinthecylinderexplodes,drivingthepistondown.Thecombustionprocesspushesthepistondownthecylinderwithgreatforceturningthecrankshafttoprovidethepowertopropelthevehicle.Eachpistonfiresatadifferenttime,determinedbytheenginefiringorder.Atthistime,intake,exhaustvalveisstillclosed.13Engineworkingprinciples任务实施Bythetimethecrankshaftcompletestworevolutions,eachcylinderintheenginewillhavegonethroughonepowerstroke.However,foradieselengine,thedieselfuelisinjectedathighpressureintothehotcompressedairandmixestoformacombustibleair/fuelmixture.Theheatoftheairignitesthefuelmixture.ExhauststrokeTherotationofthecrankshaftcausesthepistontoreturnupthecylinder.Theinletportremainsclosedbuttheexhaustportisnowopened.Themovementofthepistontowardsthetopofthecylinderthereforeforcestheburntgasesoutofthecylinderviatheexhaustport.Attheendoftheexhauststroke,theexhaustportclosesandtheinletportre-opensforthenextinductionstroke.14Engineworkingprinciples任务实施Engineoverallstructure

Theengineconsistsofalargenumberofparts(shownasFig.3.1.2).Themaincomponentsofenginearecylinderblock,pistons,connectingrods,crankshaftandvalves.

Thecylinderwiththesimplestform,iscirculartube,whichisclosedatoneend.Thepistonfitscloselyinsidethecylinder.Ideallyitwouldbeperfectlygas-tightyetperfectlyfreetomoveupanddowninsidethecylinder.Theconnectingrodconnectsthepistontothecrankshaft.Atthepistonendofconnectingrodisaswivelpincalledthe‘gudgeonpin’.Thegudgeonpinisfittedintoholesinthepistonandtheconnectingrod,thuscouplingthemtogether.Thecrankshaftisthemainshaftoftheengineandiscarriedinbearingsinthecrankcase.Offsetfromthemainpartoftheshaftisthecrankpintowhichtheconnectingrodisfittedandisfreetoturn.Theotherpartsarejoinedtogethertoformsystems.Thesesystemsarethefuelsystem,valvesystem,ignitionsystem,coolingsystem,lubricationsystem.Eachofthemhasadefinitefunction.15Engineworkingprinciples任务实施EnginesizeTheusualmethodofindicatingthesizeofanengineistostatethevolumeofairandfueltakenintotheengineforeachcycleofoperations.ThismeansthevolumecontainedinthatpartofthecylinderbetweentheTDCandBDCpositionsofthepiston.ThevolumeofacylinderisgivenbytheformulaV=πr2horV=πd2h/4.WhereVisthevolumeofthecylinder,ristheradius,dthediameterandhtheheightorlength.Theinternaldiameteroftheenginecylinderiscalledthebore,whilstthedistancethepistonmovesbetweenTDC(TopDeadCenter)andBDC(BottomDeadCenter)iscalledthestroke(showninfigure3.1.3).Representingthesebydandl,respectively,theaboveformulacanbewritten:V=πd2l/4.Sincethisisthevolumedisplacedorsweptbythepiston,itiscalledthedisplacementvolumeorsweptvolumeofthecylinder.Iftheenginehasseveralcylinders,asmosthave，thetotalsweptvolumeoftheengineissweptvolumepercylindermultipliedbythenumberofcylinders.16Engineworkingprinciples任务实施CompressionratioItisanimportantparameterofanenginecylinder.WhenthepistonisatTDC,aspaceisleftbetweenitstopandtheendofthecylinder:thevolumecontainedinthisspaceiscalledtheclearancevolume.ThevolumeenclosedabovethepistonatBDCconsistsoftheclearancevolumeplusthesweptvolumeandiscalledthetotalvolume.17Engineworkingprinciples任务实施TorqueandpowerWhenenginesarediscussed,thereareusuallytwotermsusedtoindicatehow‘powerful’anengineis:torqueandpower.Althoughthereisarelationshipbetweentorqueandpower,theyareinfactdifferentmeasurementsofwhatanenginecanachieve.Thevaluesoftorqueandpowerprovideindicationsoftheperformancethatcanbeexpectedfromanengine.Torqueisgenerallyassociatedwithstrongpullingpower,whichwouldbetypicallyrequiredinavehiclethathastopullheavyloadssuchasalargecommercialvehicleorheavygoodsvehicle.Powerisgenerallyassociatedwithenginesthatareintendedtoproducehighvehiclespeeds.Racingcarsandsportscarswouldgenerallyhavehigh-powerengines.18Task2

Crank-connectingrodsandvalvemechanism

1.Newwordsandexpressionsmechanism[ˈmɛkəˌnɪzəm]n.机械装置、构造,机制fulfill[fulˈfil]t.履行(诺言等)、完成(任务等)、实现；执行(命令等)、服从；达到(目的)potential[pəˈtenʃəl]adj.潜在的,有可能的rotary[ˈrəutəri]adj.(机器或设备)转动的；(运动)旋转的、绕轴转动的severe[siˈviə]adj.极为恶劣的、十分严重的；精确的；严谨的withstand[wiðˈstænd]vt.经受,承受corrosion[kəˈrəʊʒən]n.腐蚀、侵蚀、受腐蚀的部位；腐蚀生成物如绣等、衰败crankcase['kræŋkkeis]n.曲轴箱constitute[ˈkɔnstitju:t]vt.构成、组成；建立、制定backbone[ˈbækˌbəʊn]n.脊骨、脊柱；骨干、支柱、主力、中坚、基础accessory[ækˈsesəri]n.附件、配件、附属物；知识准备19sufficient[səˈfiʃənt]adj.足够的、充足的film[film]n.影片,电影；胶片,胶卷；薄层,薄膜stiffness[ˈstɪfnɪs]n.刚度attachment[ə'tætʃmənt]n.附着,附属；附属物,附件valve[vælv]n.阀、活门；真空管emission

[iˈmiʃən]n.发出，发光，放射物simultaneously同时地punctually['pʌŋktʃʊəlɪ]adv.如期地,准时地tappet['tæpit]n.梃杆,凸子rocker['rɔkə]n.(摇椅等底部)弯形摇臂、摇滚青年inefficiency[ɪnə'fɪʃənsɪ]n.无效率;无能无效率事例retainer[ri'teinə]n.护圈,定位器belt[belt]n.腰带、带子、区域、地带chain[tʃein]n.链、锁链、一系列的事物、连锁店或旅馆、束缚cylindrical[sə'lɪndrɪkəl]adj.圆柱形的、圆筒状的、气缸(或滚筒)的intermediate[,ɪntə'mi:djət]adj.中间的、中级的reliability[rɪlaɪəbɪlətɪ]n.可靠、可信赖知识准备20durability['djʊrəbɪlətɪ]n.耐久性、耐用性cam[kæm]n.凸轮compressionring压缩环（气环）pressure-tight耐压密闭的alignwith使一致；使密切合作besubjectedto经过～、易于～、遭受valvestem气门杆valveguide阀导承、阀杆导承、气阀导管、气门导管lockingplate锁紧木片、锁片、防松板、定闹盘pushrod制动缸推杆、顶杆、挺杆、推杆chaindrive链传动withregardto关于timinggear正时齿轮VariableValveTiming可变气门正时知识准备21Crankandconnectingrodmechanism

任务实施Thecombinationofcrankandconnectingrodinaninternalcombustionengineformsakindofmechanismthatcanfulfillworkingcycleandconvertthepotentialenergyofthefuelintothekineticenergywhichrotatesthecrankshaft.Itsfunctionistoachieveenergyconversiontotransmitforceandchangethereciprocatingmotionofthepistonintotherotarymotionofthecrankshaft.Theworkingconditioninthismechanismisrathersevereduetowithstandinghightemperature,highpressure,high-speedandchemicalcorrosion.22Automobilecategory

任务实施Thecrankandconnectingrodmechanismcanbedividedintothreegroups,suchastheenginebody,piston-connectingrodandcrankshaft-flywheelgroup.Amongthem,thebodyconstitutesthebackboneoftheengine,whichisregardedasabaseontheinternalandexternalinstallationofallthemajorpartsandaccessoriesinanengine.Thebodymusthavesufficientstrengthandstiffnessbecauseitissubjectedtovariousloads.Itismainlycomposedofthecylinderblock,crankcase,cylinderhead,cylindergasketandotherparts(shownasthefigure.3.2.1).Thisgroupaboutpiston-connectingrodconsistsofpiston,pistonring,pistonpin,connectingrodanditsbearinghalfshells(illustratedinFigure3.2.2).Thegroupofcrankshaft-flywheelismainlycomposedofcrankshaft,flywheelandotheraccessories(shownasFigure.3.2.3)23AutomobileClassification任务实施2425Valveoperatingmechanism任务实施Thevalveoperatingmechanismisusedtocontroltheintakeandexhaustports,whichprovidestimelyadmissionofthefreshchargeintothecylindersandemissionofexhaustgases.Simultaneously,thevalvespunctuallyopenandclosethoseportsinthecylinderheadthroughwhichthecylinderscommunicatewiththeintakeandexhaustmanifoldaccordingtotheignitionorderofthecylinderandtheprocessrequirements.Thevalvegeariswidelyappliedinthefour-strokeengines.2627Valveoperatingmechanism任务实施Thevalvegeariscomposedoftwoparts,includingthevalvegroupandthevalvedrivegroup(showninFig.3.2.4).Eachgroupcontainssomecomponentsorparts,suchasvalves,valvebosses,valveguides,valvesprings,lockingplate,retainer,camshaft,tappet,pushrod,rockerarmetc..Accordingtothedifferentlocationofvalvesandcamshafts,thelayoutwillbedifferent.Forexample,valvesarelocatedonthetoporthesideofthecylinder.Camshaftsaresetonthebeneath,themidortheoverhead(showninFig.3.2.5).Thesearrangementsarerespectivelyusedindifferentengines.Duetotheinefficiencyofside-valveengines,vehiclemanufacturesnolongerusethislayout.2829Valveoperatingmechanism任务实施Asforthecamshaftdrive,therearethreewayssuchasbeltdrive,chaindriveandgeardrive(showninfigure3.2.6).Generallyspeaking,themechanismwithboththebeneathcamshaftandthemidcamshaftismostlyadoptedthecylindricaltiminggeardrive.Itusuallyneedsjustapairoftiminggearsfromcrankshafttocamshaft.Ifthegeardiameteristoolarge,anintermediategearmaybeadded.Thechaindriveissuitablefortheoverheadcamshaft,butthereliabilityandthedurabilityofthedriveisnotasgoodasthatofthegeardrive.Inrecentyears,thetoothedbeltwithlownoiseandlowcostiswidelyusedinhigh-speedcarengineinsteadofthedrivechain.3031Task3ElectronicFuelInjectionsystem

1.Newwordsandexpressionscarburetor['kɑ:bjʊretə]n.汽化器,化油器sensor

[ˈsensə]n.传感器,灵敏元件appropriate

[əˈprəupri-it,əˈprəuprieit]a.(适)恰当的pressurize['preʃə,raɪz]vt.对…施加压力、给…增压nozzle['nɔzəl]n.管嘴、喷嘴injector[in'dʒektə]n.喷油器discharge[dis'tʃɑ:dʒ]vt.执行、履行spray[sprei]vt.&vi.喷n.浪花、飞沫、喷雾

circuit

[ˈsə:kit]n.电路，线路；vibration

[vaiˈbreiʃən]n.颤动；振动atomize['ætəmaiz]v.使分裂为原子、将…喷成雾状知识准备32degreeofrichness浓度air-fuelratio空燃比integratewith与…结合在一起fuelconsumption燃料消耗（量），耗油率wiringharness线束electronicfuelinjection(EFI)电子燃油喷射throttlebody节气门体intakemanifold进气歧管知识准备33ElectronicfuelInjectionsystem

任务实施Onoldcars,itisacarburetorthatsendsthecorrectair-fuelmixturetotheengine.Thecarburetorisamixingdevicewhichmixesliquidgasolinewithair.Themixturemustvarydegreeofrichnesscontinuallytosuitengineoperationconditions.Therefore,theelectricfuelinjectionsystemhasreplacedthefunctionofthecarburetorinmoderncarengines.Fuelinjectionsystemprovidesmoreexactair-fuelratiocontrol.Thus,enginedevelopsbettereconomyandemissioncontrol.Sensorsreadchangesontheengine.Acomputerinterpretstheinformationandsendsappropriateinstructiontotheengine’sfuelcontroller.Thentheinjectorspraysameasuredamountoffueldowntotheengine.34ElectronicfuelInjectionsystem任务实施Theterm‘petrolinjection’isusedtodescribeanysysteminwhichpressurizedfuelisforcedoutofanozzleinanatomizedstatetomixwithasupplyofair.Modernsystemsarecontrolledelectronicallybecausethisformofcontrolenablesthefuelquantitytobeaccuratelysettosuittheengineoperatingconditions.Strictemissioncontrolregulationshavedemandedprecisemeteringofthefuel,andalthoughpetrolinjectionsystemsaremoreexpensivethancarburetorfuelsystems,theyarenowusedtocontrolthefuellingonallengines.Mostpetrolinjectionsystems(figure4.3.1)areintegratedwiththeignitionsystemintoanenginemanagementsystem,includingthreesystems(fueldelivery,airinduction,electroniccontrol).35ElectronicFuelInjectionSystem任务实施Apetrolinjectionsystemthatdeliversthecorrectquantityofhighlyatomizedfuelgivesthefollowingadvantages:(1)lowerexhaustpollution.(2)lowerfuelconsumption.(3)higherpoweroutput.(4)smootherengineoperationduetoanevenpoweroutputfromeachcylinder.(5)automaticadjustmentoftheair/fuelratiotosuitalloperatingconditions.Thefueldeliverysystem（Fig.3.3.2）istosupplytheinjectorswiththefuel.Pressureisprovidedbyanelectricfuelpump.Somesystemsusetwopumps:alow-pressurefuelpumpthatdeliversfueltoanotherpump,whichdevelopsthepressure.36Figure3.3.2Fueldeliverysystem37ElectronicFuelInjectionSystem任务实施Theairsupplysystem(Figure3.3.3)istoinducethefreshairtoformthemixtureinthecylinder,consistingofanaircleanerassembly,throttlebody,andintakemanifold.Thethrottlebodysectioncontainsthethrottlevalve,whichisopenedandclosedbythedrivertocontroltheamountofairenteringtheintakemanifold.Onthrottlebodyfuelinjectionsystems,thethrottlebodyalsocontainsthefuelinjectioncomponents.Theintakemanifoldformsaclosedpassagebetweenthethrottlebodyandthecylinderhead.38Figure3.3.3Theairinductionsystem39ElectronicFuelInjectionSystem任务实施TheelectroniccontrolsystemofanengineismainlycomposedofECU,sensorsandactuators(showninFigure3.3.4).Enginecontrolcomputersareconstructedusingmanydifferentelectroniccircuitsandcomponents.Moderncomputerscontrolmanyotherenginesystemsinadditiontothefuelinjectors.Thecomputerisusuallylocatedinaprotectedareaawayfromenginevibrationandheat,andisconnectedtotherestoftheinjectionsystembymeansofasealedwiringharnessplug.Thecomputerreceivessignalsfromanumberofsensorswhenevertheengineisrunning.Fromthisinput,thecomputerevaluatesenginefuelneedsandadjustsinjectorpulsewidthaccordingly.4041Task4Thelubricationsystem

1.Newwordsandexpressionscirculate

[ˈsə:kjuleit]v.(使)循环；(使)流传friction

[ˈfrikʃən]n.不和，抵触；摩擦(力)lubricant

[ˈlu:brikənt]n.润滑剂,润滑油minimize

[ˈminimaiz]vt.使减(缩)小到最低wear

[wɛə]vt.穿(戴)着；磨损overhaul[,əʊvə'hɔ:l,'əʊvə,hɔ:l]vt.彻底检查、大修n.检查、大修splash[splæʃ]vt.使(液体)溅起vi.(指液体)溅落droplet['drɔplit]n.小滴mist[mist]n.薄雾、视线模糊不清vt.&vi.(使)蒙上薄雾gallery['ɡæləri]n.画廊,美术馆；走廊strainer['streɪnə]n.滤器;滤盆、滤网quantificationally[kwɒntɪfɪ'keɪʃənəlɪ]adv.定量（化）地grease

[gri:s]n.油脂；润滑油vt.用油脂涂，加润滑油知识准备42indetail详细地cylinderwall汽缸壁splashlubrication飞溅润滑mainoilgallery主油道oilfilter(汽车等)机油滤清器oilpressureregulator油压调节器oilstrainer集滤器reliefvalve安全阀、泄压阀oilcooler机油冷却器知识准备43Thelubricationsystem

任务实施Itisveryimportantforthelubricationsystemtoberequiredtolubricatethemovingpartsofanengineconstantly.Itisusedforcollecting,cleaning,coolingandre-circulatingoilintheengine.Themainfunctionofthelubricationsystemistocirculateanddeliveroiltothesurfacesofallthemovingpartsinordertoreducefrictionbetweenthem.Indetail,thelubricantcirculatesthroughtheenginemovingpartsandperformsimportantjobs:(1) Tolubricatemovingpartstominimizewear.(2) Tolubricatemovingpartstominimizepowerlossfromfriction.(3) Toremoveheatfromenginepartsbyactingasacoolingagent.(4) Toabsorbshocksbetweenbearingsandotherengineparts,thusreducingthenoiseandextendingtheenginelife.(5) Toformagoodsealbetweenpistonringsandcylinderwalls.(6) Toactasacleaningagent,washingtheworkingsurfacesfreeofchemicaldeposits,dustanddirttoprotectthemfromcorrosion.44Thelubricationsystem任务实施Tokeepacaringoodrunningconditions,acarownermustchangethelubricantonceevery5000km.Ifthelubricatingsystemshouldfail,notonlywilltheenginestop,butalsosomepartsarelikelytobedamagedbeyondrepair.Therefore,whenlubricationfailureoccurs,theenginecanseldomberunagainwithoutamajoroverhaul.Themaincomponentsofthesystemareoilpump,oilfilters,mainoilgalleries,oilpan,oilpressureregulators,reliefvalve,oilcoolersandsoon.Figure3.4.1showsthelubricationsystemlayout.Thelubricationwaycomprisesthreetypes:splashlubrication,pressurelubricationandregularlubrication.Thesplashlubricationisasimplemethodtolubricatethefrictionsurfacesviausingthoseoildropletsoroilmistsplashedupbythemovingpartswhentheengineworks.Pressureorforcedlubricationiscarriedoutbytheoilpumpsupplyingcontinuouslytheoilwithacertainpressuretothemajorityofengineparts,especiallytomainbearingsandconnectingrodbearings.Theregularlubricationisfulfilledbyaddingsomeakindoflubricatinggreaseregularlyandquantificationally.4546Task5Thecoolingsystem

1.Newwordsandexpressionstransfer[træns'fə:]vt.&vi.转移、迁移crack[kræk]vt.&vi.开裂、破裂n.裂缝、缝隙coolant['ku:lənt]n.冷冻剂、冷却液、散热剂passage['pæsidʒ]n.通道、过道、通过、消逝radiator['reɪdi:,eɪtə]n.(暖气设备的)散热器、汽车引擎的冷却器、散热器thermostat['θɜ:mə,stæt]n.恒温(调节)器hose[həuz]n.软管、胶管、水龙头surround[sə'raund]vt.包围centrifugal[sen,trɪfjəgəl,-,trɪfə-]adj.离心的fluid['flu:ɪd]n.液体、流体impeller[im'pelə]n.推进者、叶轮plunger['plʌndʒə]n.橡胶吸盘、搋子、活塞、柱塞知识准备47braze[breiz]vt.铜焊、用黄铜镀或制造fin[fin]n.(汽车、飞机、炸弹上的)尾翅flatten['flætn]vt.&vi.变平、使(某物)变平surge[sə:dʒ]n.浪涛般汹涌奔腾vi.(人群等)蜂拥而出regulate['reɡjuleit]vt.控制、管理、调整、调节channel['tʃænl]n.通道、途径bypass['baipɑ:s]vt.绕过、避开n.旁道withoutdoubt毫无疑问waterjacket水套liquidcooling液体冷却，液冷centrifugalforce地心引力smallcirculation小循环知识准备48Thecoolingsystem任务实施Withoutdoubt,theburningofthefuel/airmixtureinsidethecylindersofanenginewillproduceagreatdealofheat.Iftheheatisnottransferredtimelyoutside,theenginewillnotworknormallyduetotoohightemperature.Somepartswillbesubjectedtoexpandtoomuchandsticktogetherorcrack.ThefunctionofthecoolingsystemistokeeptheengineatitsmostefficientoperatingtemperaturebytransferringtheheattotheItissaidthatab