机械原理 英汉双语 教学课件 作者 张春林 Chapter 8 Design of Gear Trains.pptx

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1、Chapter8DesignofGearTrains8.1ClassificationofGearTrainsAgeartrainisacombinationofgearsusedtotransmitmotionfromoneshafttoanother.Fig8-1ashowsagearboxinanautomobile;therearemanypairsofgearstotransmitdifferentmotion.Fig8-1bshowsaquartzwatchinwhichthehourhand,minutehandandsecondhandrotateastheirdef

2、initegearratiostoindicatethetimes.Fig.8-1　Applicationofgeartrains(轮系的应用)1、2—clutch(离合器)　3、4—drivingshaft(输入轴)　5—geartrain(轮系)1.OrdinaryGearTrains1)Simpleordinarygeartrain.Itisageartraininwhicheachshaftcarriesonlyonegear,asshowninFig8-2a.2)Compoundgeartrain.Itisageartraininwhichatleastoneshaft

3、carriesmorethanonegear,asshowninFig8-2b.Thiswillbeaparallelorseriesparallelarrangement,ratherthanthepureseriesconnectionsofthesimplegeartrains.3)Revertedgeartrain.Iftheaxesofinputgearandoutputgearinacompoundgeartrainarecoincident,thisiscalledarevertedgeartrain,asshowninFig8-2c.。Fig.8-2　Classif

4、icationofordinarygeartrains(定轴轮系分类)2.EpicyclicGearTrainsAgeartrainhavingarelativemotionofaxesiscalledaepicyclicgeartrainorplanetarygeartrain,asshowninFig8-3a.Iftheaxesofthegearsinanepicyclicgeartrainarefixed,thesegearsarecalledsungearsorcentralgears,suchasgears1and3inFig8-3a,denotedasK.Thegearw

5、hoseaxisrotatesabouttheaxesofthesungearsistheplanetgear,suchasgear2.ThelinkwhichispivotedtotheframeatpointOandcarriestheplanetgear2tomaintaingears1,2and3inmeshisthearmorplanetcarrier,denotedasH.Fig.8-3　Epicyclicgeartrain(周转轮系)3.CombinedGearTrainsFig.8-4　Combinedgeartrains(混合轮系)Quiteoftenageart

6、rainmaycontainthecombinationofordinarygeartrainsandepicyclicgeartrainsorsomeplanetarygeartrains.Fig8-4ashowsageartrainwhichconsistsofanordinarygeartrainandaplanetarygeartrain.Fig8-4bshowsageartrainwhichconsistsoftwoplanetarygeartrainsinseriesconnection.8.2RatioofOrdinaryGearTrainswewillstudyho

7、wtodeterminetheratiosofthegeartrains.Theratioofageartrainisthattheangularvelocityoftheinputgearisdividedbytheangularvelocityoftheoutputgear,denotedas:Whereωinistheangularvelocityoftheinputgear,andωoutistheangularvelocityoftheoutpu