液压与气压传动英汉双语 教学课件 作者 陈淑梅第3章Chapter_3.ppt

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1、Chapter3HydraulicPumpsChapterlist3.1Introduction3.2PistonPumps3.3VanePumps3.4GearPumps3.1Introduction3.1.1OperatingPrincipleHydraulicpumpsconvertmechanicalenergyintohydraulicenergy.Theysupplyfluidtothecomponentsinthehydraulicsystem.Fig.3-1Displacementpumpsoperation1,2-Non-returnvalve;3-Spring;4-C

2、ylinder5-Piston;6-EccentricwheelTheoperatingprincipleofeverypumpinahydraulicsystemdependsuponthealternativechangeoftheirworkingvolumes.Note:thepistondiameterasd,theoffsetoftheeccentricwheelase,thelongeststrokethepistoncanreachassandthedischargedoilvolumeV,thenAsdescribedabove,thebasicconditionsth

3、atconstitutedahydraulicpumpcanbeconcludedasfollows:(1)Oiltightchamber(2)Flow-deploying(separatethelowpressurefromthehighone)（3)Theabsoluteoilpressureinthereservoirshouldbeequalormorethantheatmosphericpressure3.1.2Mainperformanceparametersinhydraulicpumps1.Pressure(1)Suctionpressure——thepressurein

4、theinletport.Forself-primingsuctionpumps,thesuctionpressureislowerthantheatmosphericpressure.(2)Workingpressurep——theoutletpressurewhenthehydraulicpumpisinoperation,whichdependsupontheoverallloads.(3)RatedpressurepS——thehighestpressuretestedwithstandardmethodwhenthepumprotatescontinuouslyundercom

5、monworkingconditions.2.Deliveryflowrateandvolumetricefficiency(1)DeliveryV（2）FlowrateTheflowrateconsistsoftheaveragetheoreticalflowrate,thepracticalflowrateandtheinstantaneoustheoreticalflowrate.AveragetheoreticalflowrateqtPracticalflowrateqInstantaneoustheoreticalflowrateqshRatedflowrateqs3.Powe

6、randefficiency(1)Inputpowerpr(2)OutputpowerP(3)Volumetricefficiencyηv(4)Mechanicalefficiencyηm(5)Overallefficiencyηandmechanicalefficiencyηm4.Rotatingspeed(1)Ratedrotatingspeedns:thehighestrotatingspeedfornormalcontinuousandlong-timeoperationunderratedpressure.(2)Highestrotatingspeednmax:thehighe

7、strotatingspeedforshort-timeoperationunderratedpressure,whichmaybehigherthanns.(3)Lowestspeednmin:thelowestspeedofthepumpfornormaloperation.(4)Rangeofrotatingspeed:thespeedrangebetweennminandnmax.3.1.3Performancecurves