汽车专业英语(幻灯片)chapter 3 engine(2.1-2.4)

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1、Review1:EngineTermsTDC（topdeadcenter）:thepositionofthecrankandpistonwhenthepistonisfartherawayfromthecrankshaft.BDC（bottomdeadcenter）:thepositionofthecrankandpistonwhenthepistonisnearestawayfromthecrankshaft.2.1:principleofoperationStroke:thedistancebetweenBDCandTDC;st

2、rokeiscontrolledbythecrankshaft.Four-strokeTwo-strokesweptvolume:thevolumebetweenTDCandBDC.Bore:theinternaldiameterofthecylinder.enginecapacitycompressionratioClearancevolume:thevolumeofspaceabovethepistonwhenitisatTDC.Enginecapacity:thisisthesweptvolumeofallcylinders.

3、Compressionratio:(sweptvol+clearancevol)/(clearancevol)Thespark-ignitionengineisaninternal–combustionenginewithexternallysuppliedinignition,whichconvertstheenergycontainedinthefueltokineticenergy.Thecycleofoperationsisspreadoverfourpistonstrokes.Tocompletethefullcyclei

4、ttakestworevolutionsofthecrankshaft.火花点火式发动机是一个外部提供点火的内燃发动机，它把燃料中的能量转化成动能．工作循环分布在活塞的四个行程，完成整个行程曲轴需要转两周．Intake(induction)strokeReview2:Listthefourstrokesofafour-strokeengine.CompressionstrokePowerstrokeExhauststrokeCrankshaftandconnectingrodssystemReview3:Listthemainsys

5、temsofagasolineengine.ValvesystemFuelsystemIgnitionsystemLubricationsystemCoolingsystemStartingsystemEnergyandpower:Enginesusedinautomobilesareinternalcombustionheatengines.Theyconvertthechemicalenergyofthegasolineintoheatwithinapowerchamberthatiscalledacombustionchamb

6、er.Heatenergyreleasedinthecombustionchamberraisesthetemperatureofthecombustiongaseswithinthechamber.Theincreaseingastemperaturecausesthepressureofthegasestoincrease.Thepressuredevelopedwithinthecombustionchamberisappliedtotheheadofapistontoproduceausablemechanicalforce

7、,whichisthenconvertedintousefulmechanicalpower.Engineterms:Linkingthepistonbyaconnectingrodtoacrankshaftcausesthegastorotatetheshaftthroughhalfaturn.Thepowerstroke"usesup"thegas,someansmustbeprovidedtoexpeltheburntgasandrechargethecylinderwithafreshpetrol-airmixture:th

8、iscontrolofgasmovementisthedutyofthevalves;活塞通过连杆和曲轴连接，使得气体带动曲轴旋转半圈。作功冲程耗尽了所有的气体，这样就必须采取相应的措施排出废气以及向气缸内充入新鲜的可燃混合气：气体的