液压与气压传动（英汉双语）第2版 教学课件作者 陈淑梅 第1章 Chapter-1

Chapter1IntroductiontoHydraulicandPneumaticTransmission1.1StudyonHydraulicandPneumaticTransmission1.2OperatingPrinciplesofHydraulicsTransmission

1.3CompositionofHydraulicTransmissionSystem

1.4FeaturesofHydraulicandPneumaticTransmission1.5TheDevelopmentHistoryandApplicationofHydraulicandPneumaticTechnologyChapterlistmedium：Fluidmediumenergyofcompressivefluid(pressureoilorcompressiveair)mediumcontrolmeansthecontents1.1StudyonHydraulicandPneumaticTransmissioncontrolmeans

：Hydraulicandpneumatictransmissionsaresimilarinoperatingprincipleandcontrolmeans.Specialsub-circuitsbuiltbyvarioushydraulic(orpneumatic)componentsareusedtobuildupparticularhydraulic/pneumatictransmissionsystemstorealizeenergytransferandcontrol.contents：(1)Physicalperformancesandstatic/dynamiccharactersoffluid.(2)Operatingprincipleandconstructseveralhydraulicelementsandsub-circuit(3)Hydraulic/pneumaticsystemdesignsarethebestwaytostudypower(hydraulic/pneumatic)transmissionandcontroltechnology.1.2OperatingPrinciplesofHydraulicsTransmissionPascal’slaw：pressureexertedonaconfinedliquidistransmittedundiminishedinalldirectionsandactswithequalforceonallequalareas.Fig.1-1Operatingprincipleofhydraulicjack

1-Smallactuator2-lever3-Heavyload4-Bigactuator5-Checkvalve6-Reservoir7,8-Non-returnvalve

（1-2）（1-1）1.

Powertransmission

Thusthemovingpistoncandoworkonanoutsideload.Wecangetthefirstimportantlawherethattheworkingpressuresinthehydraulicsystemdependedontheoutsideload.thehydraulicpressureintheactuator：thethrustonthesmallpistonofpumpF1：（1-4）Wecangetthesecondimportantlawherethatthemotionspeedofpistoninactuatordependsontheflow-inrate,andindependentoftheoutsideload.

Hydraulicoilpressureandtheflowratearethetwomainparametersinthehydraulicsystem.2.MotiontransferThevolume

ofdisplacementisequaltothevolumedrawnintoit,soweget（1-3）Dividingbythemovingtimetonthetwosidesintheaboveformula,wehave1.3ComposingofHydraulicTransmissionSystem

Fig.1-2Principleofatypicalhydraulicsystem

1-Hydraulicpump2-Adjustablethrottlevalve3-Closed-centerdirectionalvalve4-Hydrauliccylinder5-Workingload6-Reliefvalve7-Filter8-ReservoirFromanoperationalstandpoint,anyhydraulicsystemscanbedividedintofivelogicalsegments.（1）Powerinputsegment(energyportion):mechanicalforce→hydraulicpower.itusuallyconsistsofpumps.（2）Thepoweroutputportion(actuatorportion):

hydraulicpower→mechanicalforce.（3）Controlelements:

itcanbeusedinahydraulicsystemtorestrictthepressure,regulatethevolumeofoildirectedtoorfromtheactuator.（4）Assistantelements:

canbeusedastomaintainsystemworking（5）Workingoil:hydraulicoil.

2.Theadvantagesandshortages

ofpneumatictransmission

1.4FeaturesofHydraulicandPneumaticTransmission1.Theadvantagesanddisadrantages

ofhydraulictransmission

Advantages:1)Thehydraulicequipmentsystemhassmallervolume,light,highpowerconsistencyandcompactconfigurationatagivenpower.2)hasagoodworkingstability.3)canreachawiderangeofspeedregulation4)Thehydraulictransmissioncaneasilyrealizeautomation.5)canprotectfromover-loadeasily.6)thehydraulicsystemiseasierindesign,fabricationandapplication.7)Thehydraulicsystemiseasierthanmachineequipmentindoinglinemotion.Disadrantages:1)OilLeaksareinevitable.2)Workingtemperature.3)Thecostishigh.4)Itisdifficulttofindthereasonsoffault.Advantages:1)Theaircanbeobtainedandexpelledfromtheatmosphere.

2)Itisoflowviscosityandlowerpressurelossinpipes.3)Itisoflowworkingpressure.4)Thepneumatictransmissionhasasimpleservicing.5)SafetyDisadrantages:1)theworkingstabilitiesarepoorerthanthoseofhydraulictransmissionsystem.2)Thepushforceofpneumatictransmissionisusuallyverylower..3)Lowertransmissionefficiency.Hydraulictransmissionhasbeenexperiencingtheprocessasbelow.

The17thand18thcenturies—aproductiveperiodinthedevelopmentofhydraulictheory.The18thcentury—Thisprinciplewasfirstused.ThefirsthydraulicpressuremachinewasmanufacturedbyEnglandlateinthe18century.

The19centurytonow—HydraulicandPneumatictechnologyhaveagreatapplication……Intheworldwarone……andworldwartwo…….p9.1.5TheDevelopmentHistoryandApplicationsofHydraulicandPneumaticTransmissionTab.1-1ExamplesofapplicationhydraulicandpneumatictransmissiontechnologyinindustriesFieldsExamplesEngineeringmachineGrab,loadingmachine,bulldozer,shovelmachine,etc.MinemachineCharge,digger,elevator,hydraulicsupportetc.ArchitecturemachinePiledriver,jack,flatmachine,etc.MetallurgymachineRollingmill,pressmachine,etc.fabricationToolmachine,numeric-controlmachiningcenter,automaticassemblyline,air-spanner,punch,model-forgemachine,etc.LightindustriesPacker,injection-plasticmachine,Foodpackager,vacuum-platingmachine,printinganddyeingmachine,etc.AutomobileindustryHighaltitudeoperatingcar,lift,redirector,etc.W