车辆工程专业英语.pdf

《车辆工程专业英语.pdf》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。

1、Unit2TheBasicPrincipleofEngineTextAClassificationandMainComponentsofEngineTheinternalcombustionengineisanengineinwhichthecombustionoffueloccurswithoxygen(usuallyair)inacombustionchamber,asshowninFig.2.1.912834765Fig.2.1InternalCombustionEngine1—thecapofthecylinderhead2—valve3—engineblock4—flywh

2、eel5—crankshaft6—oilpan7—pulley8—cylinder9—timinggearClassificationofEngineTheenginecanbeclassifiedinfollowingways:ByFuelSystemGasolineengineanddieselengineareused.Inagasolineengine,theair-fuelmixtureisexplodedintheengine.Adieselengineusesdieselfuel.Itgenerateshighpoweratlowspeeds.Thefueleffic

3、iencyisbetterthanthatofagasolineengine.Unit2TheBasicPrincipleofEngineByCylinderArrangementMostcarshavemorethanonecylinder.Four,sixandeightcylindersarecommonused.Inamulti-cylinderengine,thecylindersareusuallyarrangedinoneofthreeways:in-line,V-type,orflat(Fig.2.2).Todaythenumberofcylindersisgrow

4、ing,thecylindersalsocanbearrangedasW-type.(a)flat(b)V-type(c)in-lineFig.2.2CylinderArrangementByCoolingSystemLiquid-cooledenginesandair-cooledenginesarebeingused.Liquid-cooledenginesarethemostcommonintheengineindustry.Therearealsootherwaystoclassifytheengines.Despiteoftheseclassifications,thes

5、tructureoftheengineisbasicallythesame.MainComponentsTheengineconsistsofseveraldifferentmechanismsandsystemsincludingcylinderblock,crankshaftandconnectingrodmechanism,valvemechanism,fuelsupplysystem,lubricationsystem,coolingsystem,ignitionsystemandstartingsystem.CylinderBlockThecoreoftheenginei

6、sthecylinder,withthepistonmovingupanddowninsidethecylinder.CrankshaftandConnectingRodMechanismThecrankshaftchangesthelinearmovementofthepistonintoarotationalmovementviaaconnectingrod.Theconnectingrodconnectsthepistontothecrankshaft.Itcanrotateatbothendssothatitsanglecanchangeasthepistonmovesan

7、dthecrankshaftrotates.ValveMechanismAvalvemechanismisagroupofcomponentsthatopensandclosestheintakeandexhaustvalvesinthecylinderheadattheappropriatetime.Themainfunctionsofthevalvegeararetoprovidetimelyadmissionofthefreshchargeinto