汽车专业英语课件-2 chapter 21-23

复习1.Discribethemainpartsofacar?说明汽车的主要组成部件（系统）有哪些？2.Vehicleclassificatin

汽车分类提问学习内容本次课学习内容、目标和重点难点学习目标难点重点PrincipleofOperationClassificationsMainpartsandsystems1.掌握内燃机的分类英文术语2.掌握机体、曲柄连杆机构、配气机构的英文术语2.了解各个系统的主要功能1.重点为记忆分类和主要部件英文专业术语2.难点需要记忆的生词偏多3.准确汉译表达也是难点Chapter2InternalCombustionEngine

2.1PrincipleofOperation

NicolausAugustOtto尼古拉斯·奥古斯特·奥托GottliebDaimler戈特利布·戴姆勒associate[ə'səu∫ieit]n.伙伴，同事，合伙人pioneer[¸paiə'niə]n.拓荒者，先驱者,开拓者；v.开辟，倡导combustion[kəm'bʌs∫ən]n.燃烧stroke[strouk]n.冲程piston['pistən]n.活塞cylinder['silində]n.气缸2.1.1

NewWordsandPhrasesChapter2InternalCombustionEngine

2.1PrincipleofOperation

valve[vælv]n.气门，阀门，阀exhaust[ig'zɔ:st]n.排气，废气intake['inteik]n.进气，进（引，吸）入compression[kəm'pre∫ən]n.压缩crankshaft['kræŋk∫ɑ:ft]n.曲轴cylinder['silində]n.气缸，圆筒charge[t∫ɑ:dʒ]n.充气，充量，充电；v.充电，增压□descend[di'send]v.

下降，下倾，下斜，下行Chapter2InternalCombustionEngine

2.1PrincipleofOperation

aspirate['æspəreit]v.吸气，抽吸throttle['θrɔtl]n.节气门，节流阀，油门，风门depression[di'pre∫ən]n.萧条(期)，凹地，洼地，低（气）压atomise['ætəmaiz]v.使雾化，喷雾，粉化innermost['inəməust]a.最内的，最内部的，最深处的，内心深处的outermost['autəməust]a.最外边的，离中心最远的maybe['meibi]ad.大概,或许,可能Chapter2InternalCombustionEngine

2.1PrincipleofOperation

aspirate['æspəreit]v.吸气，抽吸throttle['θrɔtl]n.节气门，节流阀，油门，风门depression[di'pre∫ən]n.萧条(期)，凹地，洼地，低（气）压atomise['ætəmaiz]v.使雾化，喷雾，粉化innermost['inəməust]a.最内的，最内部的，最深处的，内心深处的outermost['autəməust]a.最外边的，离中心最远的maybe['meibi]ad.大概,或许,可能Chapter2InternalCombustionEngine

2.1PrincipleofOperationmotorvehicle汽车，机动车petrolengine汽油机flammablemixture可燃混合气spark-ignition(S.I.)engine点燃式（S.I.）发动机cylinderhead气缸盖inletvalve进气门exhaustvalve排气门inductionstroke进气行程Chapter2InternalCombustionEngine

2.1PrincipleofOperationatmosphericpressure大气压力naturallyaspirated自然吸气normallyaspirated自然吸气compressionstroke压缩行程air-and-petrolcharge空气与汽油的混合气powerstroke做功行程exhauststroke排气行程spark-plug火花塞Chapter2InternalCombustionEngine

2.1PrincipleofOperation

Thefirstinternal-combustionenginetooperatesuccessfullyonthefour-strokecycleusedgasasafuelandwasbuiltin1876byNicolausAugustOtto,aself-taughtGermanengineerattheGas-motoreufabrik

DeutzfactorynearCologne,formanyyearsthelargestmanufacturerofinternal-combustionenginesintheworld.ItwasoneofOtto’sassociates–GottliebDaimler–wholaterdevelopedanenginetorunonpetrolwhichwasdescribedinpatentnumber4315of1885.Healsopioneereditsapplicationtothemotorvehicle.Petrolenginestakeinaflammablemixtureofairandpetrolwhichisignitedbyatimedsparkwhenthechargeiscompressed.Theseenginesarethereforesometimescalledspark-ignition(S.I.)engines.2.1.2

TextChapter2InternalCombustionEngine

2.1PrincipleofOperation

Theseenginesrequirefourpistonstrokestocompleteonecycle:anair-and-fuelintakestrokemovingoutwardfromthecylinderhead,aninwardmovementtowardsthecylinderheadcompressingthecharge,anoutwardpowerstroke,andaninwardexhauststroke.

Inductionstroke.Theinletvalveisopenedandtheexhaustvalveisclosed.Thepistondescends,movingawayfromthecylinderhead(Fig.2-1(a)).Thespeedofthepistonmovingalongthecylindercreatesapressurereductionordepressionwhichreachesamaximumofabout0.3barbelowatmosphericpressureatone-thirdfromthebeginningofthestroke.Thedepressionactuallygeneratedwilldependonthespeedandloadexperiencedbytheengine,butatypicalaveragevaluemightbe0.12barbelowatmosphericpressure.Chapter2InternalCombustionEngine

2.1PrincipleofOperation

Thisdepressioninduces(sucksin)afreshchargeofairandatomisedpetrolinproportionsrangingfrom10to17partsofairtoonepartofpetrolbyweight.Anenginewhichinducesfreshchargebymeansofadepressioninthecylinderissaidtobe‘normallyaspirated’or‘naturallyaspirated’.

Compressionstroke.Boththeinletandtheexhaustvalvesareclosed.Thepistonbeginstoascendtowardsthecylinderhead(Fig.2-1(b)).Theinducedair-and-petrolchargeisprogressivelycompressedtosomethingoftheorderofone-eighthtoone-tenthofthecylinder’soriginalvolumeatthepiston’sinnermostposition.Thiscompressionsqueezestheairandatomised-petrolmoleculesclosertogetherandnotonlyincreasesthechargepressureinthecylinderbutalsoraisesthetemperature.Chapter2InternalCombustionEngine

2.1PrincipleofOperation

Typicalmaximumcylindercompressionpressureswillrangebetween8and14barswiththethrottleopenandtheenginerunningunderload.Powerstroke.Boththeinletandtheexhaustvalvesareclosedand,justbeforethepistonapproachesthetopofitsstrokeduringcompression,aspark-plugignitesthedensecombustiblecharge(Fig.2-1(c)).Bythetimethepistonreachestheinnermostpointofitsstroke,thechargemixturebeginstoburn,generatesheat,andrapidlyraisesthepressureinthecylinderuntilthegasforcesexceedtheresistingload.Theburninggasesthenexpandandsochangethepiston’sdirectionofmotionandpushittoitsoutermostposition.Thecylinderpressurethendropsfromapeakvalueofabout60barsunderfullloaddowntomaybe4barneartheoutermostmovementofthepiston.Chapter2InternalCombustionEngine

2.1PrincipleofOperation

Exhauststroke.Attheendofthepowerstroketheinletvalveremainsclosedbuttheexhaustvalveisopened.Thepistonchangesitsdirectionofmotionandnowmovesfromtheoutermosttotheinnermostposition(Fig.2-1(d)).Mostoftheburntgaseswillbeexpelledbytheexistingpressureenergyofthegas,butthereturningpistonwillpushthelastofthespentgasesoutofthecylinderthroughtheexhaust-valveportandtotheatmosphere.Chapter2InternalCombustionEngine

2.1PrincipleofOperation

Fig2-1Four-stroke-cyclepetrolengineChapter2InternalCombustionEngine

2.2EngineClassifications

Fig2-1Four-stroke-cyclepetrolengineChapter2InternalCombustionEngine

2.2EngineClassifications

complicated['kɔmplikeitid]a.复杂的，难懂的，结构复杂的valvetrain['vælv'trein]n.气门机构，配气机构，气门组camshaft['kæmʃɑ:ft]n.凸轮轴diesel['di:zəl]n.柴油gasoline['gæsəli:n]n.汽油methanol['meθənəul]n.甲醇propane['prəupein]n.丙烷four-stroke-cycleengine四冲程（循环）发动机2.2.1

NewWordsandPhrasesChapter2InternalCombustionEngine

2.2EngineClassifications

roadvehicle道路车辆flat(horizontal-opposed)engine水平对置式发动机inlineengine直列式发动机V-typeengineV型发动机overheadcamshaft(OHC)顶置凸轮轴（OHC）overheadvalve(OHV)顶置气门（OHV）doubleoverheadcamshaft(DOHC)engine双顶置凸轮轴（DOHC）发动机air-cooledengine风冷发动机liquid-cooledengine水冷发动机Chapter2InternalCombustionEngine

2.2EngineClassifications

Today’sautomotiveenginescanbeclassifiedinseveralwaysdependingonthefollowingdesignfeatures:·Operationalcycles.Therearetwo-strokeandfour-strokecycles.Four-stroke-cycleenginesarewidelyusedonroadvehicles.However,afewoldercarshaveusedandsomecarsinthefuturewilluseatwo-strokeengine.·Numberofcylinders.Currentenginedesignsinclude3-,4-,5-,6-,8-,10-,and12-cylinderengines.·Cylinderarrangement.Anenginecanbeflat(horizontal-opposed),inline,orV-type.Othermorecomplicateddesignshavealsobeenused.Seefigure2-2.2.2.2Text

Fig.2-2CylinderarrangementsChapter2InternalCombustionEngine

2.2EngineClassifications

·Valvetraintype.Enginevalvetrainscanbeeithertheoverheadcamshaft(OHC)typeorthecamshaftin-blockoverheadvalve(OHV)type(Figure2-3).Someenginesseparatecamshaftsfortheintakeandexhaustvalves.ThesearebasedontheOHCdesignandarecalleddoubleoverheadcamshaft(DOHC)engines.V-typeDOHCengineshavefourcamshafts—twooneachside.Figure2-3(a)Overheadcamshaft（OHC）

Chapter2InternalCombustionEngine

2.2EngineClassifications

·Valvetraintype.Enginevalvetrainscanbeeithertheoverheadcamshaft(OHC)typeorthecamshaftin-blockoverheadvalve(OHV)type(Figure2-3).Someenginesseparatecamshaftsfortheintakeandexhaustvalves.ThesearebasedontheOHCdesignandarecalleddoubleoverheadcamshaft(DOHC)engines.V-typeDOHCengineshavefourcamshafts—twooneachside.Figure2-3(b)Overheadvalve(OHV)engines

Chapter2InternalCombustionEngine

2.2EngineClassifications·Ignitiontype.Therearetwotypesofignitionsystems:sparkignitionandcompressionignition.Gasolineenginesuseasparkignitionsystemandaresortedtosparkignitionengines.Inasparkignitionengine,theair-fuelmixtureisignitedbyanelectricalspark.Dieselengines,orcompressionignitionengines,havenosparkplugs.Anautomotivedieselenginereliesontheheatgeneratedasairiscompressedtoignitetheair-fuelmixtureforthepowerstroke.

·Coolingsystems.Therearebothair-cooledandliquid-cooledenginesinuse.Nearlyalloftoday’sengineshaveliquid-coolingsystems.·Fueltype.Severaltypesoffuelcurrentlyusedinautomobileenginesincludegasoline,naturalgas,methanol,diesel,andpropane.Themostcommonlyusedisgasolinealthoughnewfuelsarebeingtested.Chapter2InternalCombustionEngine

2.2EngineClassificationsChapter2InternalCombustionEngine

2.3Engineblockandhead

foundation[faun'dei∫ən]n.基础，基地，基金，机座，基础件accessory[æk'sesəri]n.附属品，附件，辅助装置clutch[klʌt∫]n.离合器housing['hauziŋ]n.外壳，bolt[boult]n.螺栓；v.用螺栓连接core[kɔ:]n.核心，铁心，型芯，沙芯，（电缆）芯线aluminum[ælju'miniəm]n.铝liner['lainə]n.衬套，衬里，衬板2.3.1

NewWordsandPhrasesChapter2InternalCombustionEngine

2.3Engineblockandheadengineblock气缸体cylinderblock气缸体clutchhousing离合器壳castiron铸铁cylindersleeve气缸套combustionchamber燃烧室lightvehicle轻型汽车Chapter2InternalCombustionEngine

2.3Engineblockandhead

2.3.1EngineblockTheengineblock(orcylinderblock)servesasarigidmetalfoundationforallpartsofanengine(Fig.2-4).Itcontainsthecylindersandsupportsthecrankshaftandcamshaft.Accessoryunitsandtheclutchhousingareboltedtoit.Blocksaremadeofeithercastironoraluminum.

2.3.2

TextChapter2InternalCombustionEngine

2.3Engineblockandhead

Thecylinderisaroundholeformedint