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中国汽车技术论坛：更多汽车资料请访问中国汽车技术论坛：:engine,body,chassisandelectricalequipment.1.2EngineTheengineactsasthepowerunit.Theinternalcombustionengineismostcommon:thisobtainsitspowerbyburningaliquidfuelinsidetheenginecylinder.Therearetwotypesofengine:gasoline(alsocalledaspark-ignitionengine)anddiesel(alsocalledacompression-ignitionengine).Bothenginesarecalledheatengines;theburningfuel中国汽车技术论坛：更多汽车资料请访问中国汽车技术论坛：―conveysthedrivetothewheels.Themaincomponentsareclutch,gearbox,driveshaft,finaldrive,anddifferential.Suspension―absorbstheroadshocks.Steering―controlsthedirectionofthemovement.Brake―slowsdownthevehicle.1.5ElectricalEquipmentTheelectricalsystemsupplieselectricityfortheignition,horn,lights,heater,andstarter.Theelectricitylevelismaintainedbyachargingcircuit.Thiscircuitconsistsofthebattery,alternator(orgenerator).Thebatterystoreselectricity.Thealternatorchangestheengine'smechanicalenergyintoelectricalenergyandrechargesthebattery.NewWordsPrincipalcomponent主要部件category种类，类型body车身chassis底盘layout布置powerunit动力装置internalcombustionengine内燃机cylinder汽缸gasoline汽油spark火花ignition点燃，点火diesel柴油机compression压缩中国汽车技术论坛：更多汽车资料请访问中国汽车技术论坛：（发动机）罩trunkdeck行李舱盖cargo货物styling样式assembly总成，装配suspension悬挂，悬置shock冲击steering转向，操纵brake刹车，制动器clutch离合器gearbox变速器driveshaft传动轴finaldrive主减速器，后桥differential差速器slowdown（使）慢下来，减速horn喇叭starter起动机charge充电alternator交流发电机ReviewQuestions1.Listthemainpartsofanautomobile?2.Whatarethecommontypesofavehicleaccordingtobodystyling?3.Whichsystemsdoesachassisincludeandwhatarethemainfunctionsofthechassis?4.Whyaresuspensionsystemsusedonvehicles?CHAPTER2INTERNALCOMBUSTIONENGINE2.1principleofoperation2.1.1EngineandpowerEngineisusedtoproducepower.Thechemicalenergyinfuelisconvertedtoheatbytheburningofthefuelatacontrolledrate.Thisprocessiscalledcombustion.Ifenginecombustionoccurswiththepowerchamber.,theengineiscalledinternalcombustionengine.Ifcombustiontakesplaceoutsidethecylinder,theengineiscalledanexternalcombustionengine.Engineusedinautomobilesareinternalcombustionheatengines.Heatenergyreleasedinthecombustionchamberraisesthetemperatureofthecombustiongaseswiththechamber.Theincreaseingastemperaturecausesthepressureofthegasestoincrease.Thepressuredevelopedwithinthecombustionchamberisappliedtotheheadofapistontoproduceausablemechanicalforce,whichisthenconvertedintousefulmechanicalpower.2.1.2EngineTermsLinkingthepistonbyaconnectingrodtoacrankshaftcausesthegastorotatetheshaftthroughhalfaturn.Thepowerstroke“usesup”thegas,someansmustbeprovidedtoexpeltheburntgas中国汽车技术论坛：更多汽车资料请访问中国汽车技术论坛：:TDC(TopDeadCenter):thepositionofthecrankandpistonwhenthepistonisfartherawayfromthecrankshaft.BDC(BottomDeadCenter):thepositionofthecrankandpistonwhenthepistonisnearesttothecrankshaft.Stroke:thedistancebetweenBDCandTDC;strokeiscontrolledbythecrankshaft.Bore:theinternaldiameterofthecylinder.Sweptvolume:thevolumebetweenTDCandBDC.Enginecapacity:thisisthesweptvolumeofallthecylindere.g.afour-strokehavingacapacityoftwoliters(2000cm)hasacylindersweptvolumeof50cm.Clearancevolume:thevolumeofthespaceabovethepistonwhenitisatTDC.Compressionratio=(sweptvol+clearancevol)\(clearancevol)Two-stroke:apowerstrokeeveryrevolutionofthecrank.Four-stroke:apowerstrokeeveryotherrevolutionofthecrank..2.1.3TheFour-strokeSpark-ignitionEngineCycleThespark-ignitionengineisaninternal-combustionenginewithexternallysuppliedinignition,whichconvertstheenergycontainedinthefueltokineticenergy.Thecycleofoperationsisspreadoverfourpistonstrokes.Tocompletethefullcycleittakestworevolutionsofthecrankshaft.Theoperatingstrokesare:中国汽车技术论坛：更多汽车资料请访问中国汽车技术论坛：