51单片机学习17(键盘接口)

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

2、dbythecrankshaft.Four-strokeTwo-strokesweptvolume:thevolumebetweenTDCandBDC.Bore:theinternaldiameterofthecylinder.enginecapacitycompressionratioClearancevolume:thevolumeofspaceabovethepistonwhenitisatTDC.Enginecapacity:thisisthesweptvolumeofallcylinders.Compressionratio:(sweptvol+cle

3、arancevol)/(clearancevol)Thespark-ignitionengineisaninternal–combustionenginewithexternallysuppliedinignition,whichconvertstheenergycontainedinthefueltokineticenergy.Thecycleofoperationsisspreadoverfourpistonstrokes.Tocompletethefullcycleittakestworevolutionsofthecrankshaft.火花点火式发动机是

4、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:Listthemainsystemsofagasolineengine.ValvesystemFuelsystemIgnitionsystemLub

5、ricationsystemCoolingsystemStartingsystemEnergyandpower:Enginesusedinautomobilesareinternalcombustionheatengines.Theyconvertthechemicalenergyofthegasolineintoheatwithinapowerchamberthatiscalledacombustionchamber.Heatenergyreleasedinthecombustionchamberraisesthetemperatureofthecombust

6、iongaseswithinthechamber.Theincreaseingastemperaturecausesthepressureofthegasestoincrease.Thepressuredevelopedwithinthecombustionchamberisappliedtotheheadofapistontoproduceausablemechanicalforce,whichisthenconvertedintousefulmechanicalpower.Engineterms:Linkingthepistonbyaconnectingro

7、dtoacrankshaftcausesthegastorotatetheshaftthroughhalfaturn.Thepowerstroke"usesup"thegas,someansmustbeprovidedtoexpeltheburntgasandrechargethecylinderwithafreshpetrol-airmixture:thiscontrolofgasmovementisthedutyofthevalves;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

8、新鲜的可燃混合气：气体的