油压泵简介--中英文翻译.docx

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1、外文翻译原文标题Oilpressurepumpcover油压泵简介机械工程系译文标题作者所在系别作者所在专业机械设计制造及其自动化完成时间译文标题油压泵原文标题Oilpressurepumpcover作者译名国籍原文出处原义Ahydraulicpumpisamechanicaldevicewhichconvertsmechanicalenergyintohydraulicenergy.Morespecifically,apumpconvertsthekinetic(moving)energyofarotatingshaftintothekineticenergyoffluidflow.Thef

2、luidflowalsohaspotentialenergythatallowsittoovercometheresistanceofthesystemtofluidflow.Rememberthatapumpprovidestheforceproduceflowandtransmitpower.Hydraulicpressureiscausedbytheloadonthesystemandbytheresistanceofthehydraulicsystemtofluidflow.Whenoperating,ahydraulicpumpperformstwofunctions.First,i

3、tcreatesapartialvacuumatitsinlet,permittingtheatmosphericpressureinthefluidreservoirtopushthehydraulicfluidthroughtheinletstrainerandlineintothepump.Second,itsmechanicalactiondeliversthefluidtoitsoutletandintothehydraulicsystems,asshowninFig.5-1.Asthefluidleavesthepump,itencounterstheworkingpressure

4、inthesystem.Thispressureisproducedbythepressureregulatingvalve,thesystemworkload,andflowlossesinthehydraulictubingpumpisclassifiedonthebasisofthephysicalarrangementofitspumpingmechanismanditsbasicprincipleofoperating.Pumpsclassifiedbyprincipleofoperationincludepositivedisplacementandnonpositive-diSp

5、lacementtypes.Positive-displacementpumpsareequippedwithamechanicalseparation(gears,vanes,orimpellers)betweentheinletandoutlet,whichminimizesinternalleakageorslippage.Therefore,theoutputofpositive-displacementpumpsisalmostunaffectedbyvariationsinsystempressureNopositive-displacementpumps(suchascentri

6、fugalpumps)donothaveapositiveinternalseparationagainstleakageorslippage.Becauseofthisslippage,thedeliveryofthesepumpisreducedastheworkingpressureofasystemisincreased.However,nonpositive-displacementpumpsdeliveracontinuousflow,whilepositive-displacementpumpsdeliveranintermittent(pulsating)flow.Thesep

7、ulsationsaresmallandcanbesmoothoutbytheaccumulatororthesystempiping.Mosthydraulicpumpsarepositivedisp1acementpumpsoftherotarytype.Positive-displacementpumpshaveeitherafixedorvariabledisplacement.Thevolumeofdelivery,orgpm,ofafixed-displacementpumpcanbechangedonlybychangingthespeedofthepump,becausethe

8、physicalarrangementofthepumpingmechanismcannotbechanged,(Thisdoesnotmeanthattheflowinotherportionsofthesystemcannotbeadjustedbyvalves.)Theflowofavariable-disp1acementpumpcanbechangedbychangingthephysicalarrangementofthepumpingmechanismwithabuilt-incontrollingdevice.Thisdeviceoftenfunctionsinresponse

9、tosystempressureorothersignals.Variable-displacementpumpsaremorecomplexthanfixed-displacementpumpsand,therefore,costmore.Inaddition,theefficiencyofavariable-displacementpumpislowerthanthatofafixed-displacementpump.Thisisoffsetsomewhatbythehigheroverallefficiencyofasystempoweredbyavariable-displaceme

10、ntpump.Mostpositive-displacementpumpsareclassifiedasrotarypumps.Thisisbecausetheassemblythattransfersthefluidfromthepumpinlettothepumpoutlethasarotatingmotion.Rotarypumpsarefurtherclassifiedaccordingtothemechanismthattransfersthefluid-suchasgears,vanes,orscrews.differentkindofpositive-dispIacementpu

11、mpispistonpump.Thispumpusesareciprocating(back-and-forth)motionofthepiston,alternatelytoreceivefluidontheinletside,andtodischargefluidontheoutletside.Aradial-pistonpumphasarevolvingassemblywithseveralpistonassembliesbuiltintoit,andcanbeclassifiedasarotarypump.Severaltypesofpistonpumpswillbediscussed

12、laterinthischapter.Theperformanceofdifferentpumpsisevaluatedonthebasisofmanyfactors,inculdingphysicalcharacteristics,operatingcharacteristics,andcost.Whenselectingapump,thefollowpumpratingandselectionfactorsareconsidered;CapacityPressureEnergyconsumptionDrivespeedEfficiencyReliabilityFluidcharacteri

13、sticsSizeandweightControladaptabilityServicelifeInstallationandmaintenancecostsSomeoftheperformancecharacteristicsofdifferentpumpsaregiveninTable5-1.Eachoftheseselectionfactorsisdescribedbrieflyinthefollowingparagraph.Theprimaryratingofapumpisitscapacity.Thisisalsocalledthedeliveryrate,flowrate,orvo

14、lumetricoutput.ThecapacityusualIyisgiven3/ingallonsperminute(gpm),cubicinchesperminute(rnn),orcubicinchesperrevolutionatspecifiedoperatingconditions.Pumpcapacityratingsusuallyaregivenatstandardatmosphericinletpressureandvariousoutputpressures,aswellasatapproximatefluidservicetemperatures.Thepressure

15、ratingofapumpgenerallyisbasedontheabilityofthepumptowithstandpressurewithoutanundesirableincreaseinitsinternalleakage(orslippage)ordamagetopumpparts.Pumpsarepressure-ratedunderthesameconditions(speed,temperrature,andinletpressure)atwhichtheyarecapacity-rated.Mostpumpsarepressure-ratedat100,500,1000,

16、1500,2000,3500,or5000psi.Energyconsumptionisanimportantconsiderationnotonlyintheselectionofapump,butalsointheoperatingperformanceofthepumpafterthesystemisinstalled.Theenergyrequirementforpumpingdependsonthepumpingpressure,andonthemassoffluidpumpedinagiventime.Thefluidpumpinghorsepowerisdeterminedasf