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FluidPowerTransmissionandControl-ControlComponentsinHydraulicSystems,Outline,IntroductionDirectionalcontrolvalvesPressurecontrolvalvesFluidcontrolvalvesServovalvesHydraulicfusesPressureandtemperatureswitchesShockabsorbers,Introduction,Definedasanydevicebywhichtheflowoffluidmaybestarted,stopped,orregulatedbyamovablepartthatopensorobstructspassageValvesareclassifiedaccordingtotheiruse:-directionalcontrol-pressurecontrol-flowcontrolValvesmaybecontrolledmanually,electrically,pneumatically,mechanically,hydraulically,orbycombinationsoftwoormoreofthesemethods,Directionalcontrolvalves,UsedtocontrolthedirectionofflowinahydrauliccircuitTwoclasses:one-wayvalves(checkvalves)andmulti-wayvalves,Checkvalves(止回阀,单向阀),Spring,Poppet(阀芯,锥阀结构),Body,Seat(阀座),Threadedmounting,Permitfreeflowinonedirectionandpreventanyflowintheoppositedirection,Checkvalves(止回阀,单向阀),Subplatemounting,Pilot-operatedcheckvalves(液控单向阀),Permitfreeflowinonedirectionbutpermitflowinthenormallyblockedoppositedirectiononlyifpilotpressureisapplied,Controlspool,Housing,Poppet(阀芯,截止阀),Spring,Pilotpressureport,Pilot-operatedcheckvalvewithoutpilotoildrain(内泄),Pilot-operatedcheckvalves(液控单向阀),Ballpoppetvalve(optional,释压球阀)decompressionreducepilotpressure,Poppet,Spring,Pilotoildrain(泄油口),Pilot-operatedcheckvalvewithpilotoildrain(外泄),Pilot-operatedcheckvalves,UsedfortheisolationofoperatingcircuitswhichareunderpressureFrequentlyasasafeguardagainstcreepingmovementsofhydraulicallylockedactuators,Multi-waydirectionalcontrolvalves(换向阀),Directionalcontrolvalves,Directionalspoolvalves,Directionalpoppetvalves,Directlyoperated,Pilotedoperated,Directlyoperated,Pilotedoperated,Slidingspool(滑阀),Slidingspool,Symbol,Slidingspool,FunctionpositionsPortsinthevalvehousingThepathofflow,Variouscenterflowpathsforthree-positionvalves,“Y”,“H”opencenter,“O”closedcenter,“P”,“M”,“A”,Tandem,Methodsofoperation,Manual,Handleverwithdetent,Rollerplunger,Pedal,Solenoid,Solenoid,springoffset,Solenoid,springcentered,Electrohydraulic,Pilotpressure,Slidingspool,Manual-actuated,spring-centered,threeposition,fourwayvalve,Slidingspool,Air/hydraulicpilotpressureactuated,threeposition,fourwayvalve,Slidingspool,Solenoid-controlled,pilot-operateddirectionalcontrolvalve(Electrohydraulicdirectionalvalve),Pilotvalve,Mainvalve,Slidingspool,Solenoid-controlled,pilot-operateddirectionalcontrolvalve(Electrohydraulicdirectionalvalve),Pressurecontrolvalves,Relief,Pressure-reducing,Sequence,Unloading,safe,Pressurecontrolvalves,UsedtocontrolpressurePrinciple:ThebalancebetweenhydraulicforceandspringforceTypes:-Normallyclosed:reliefvalves,unloadingvalves,sequencevalves,counterbalance-Normallyopen:pressure-reducingvalvesMountingtypes:pipeconnection,cartridge,subplate,Pressurecontrolvalves,Relief,Pressure-reducing,Sequence,Unloading,safe,Pressurecontrolvalves,Pressurecontrolvalves,Relief,Pressure-reducing,Sequence,Unloading,Directoperated,pipeconnection(管式安装),cartridge,subplate(底板安装),(插装式),Pressurecontrolvalves,Pressurereliefvalves(directoperated),Pressurereliefvalves(directoperated),Pressurecontrolvalves,Pressurereliefvalves(directoperated),Directoperated,poppetseatvalve(直动式,提升座阀型),Ascartridgevalve(插装阀),Pressurecontrolvalves,Relief,Pressurereliefvalves(directoperated),Directoperated,ballseatvalve(直动式,球阀型),Pressurecontrolvalves,Relief,Pressure-reducing,Sequence,Unloading,Directoperated,Slidingspool,Pressurereliefvalve(pilot-actuated),Pressurecontrolvalves,Relief,Pressure-reducing,Sequence,Unloading,Directoperated,Slidingspool,Pressurereliefvalve(pilot-actuated),mainvalve,pilotvalve,14:pilotline,externallybacktotank,Pressurecontrolvalves,Sequence,Unloading,Slidingspool,Pressurereliefvalve(pilot-actuated),Pilotoilsupplyandpilotoildraininternal(控制油内供内排),Pilotoilsupplyandoildrain(控制油供给及回油管路),Pilotoilsupplyexternal,pilotoildraininternal(控制油外供内排),Pilotoilsupplyinternal,pilotoildrainexternal(控制油内供外排),Pilotoilsupplyandpilotoildrainexternal(控制油外供外排),Characteristiccurves(pressurereliefvalves),Pressurecontrolvalves,Relief,Pressure-reducing,Sequence,Unloading,Slidingspool,Pressurereliefvalves,NormallyclosedUsedtodivertpumpflowtotank;usedtolimitmaximumsystempressure;provideagainstanyoverloads(safevalves)Directoperated;pilotoperated,Pressurecontrolvalves,Relief,Pressure-reducing,Sequence,Unloading,Slidingspool,Unloadingvalves,Pressurecontrolvalves,Relief,Pressure-reducing,Sequence,Unloading,Slidingspool,Unloadingvalves,Pressurecontrolvalves,Relief,Pressure-reducing,Sequence,Unloading,Directoperated,Slidingspool,Unloadingvalves,NormallyclosedUsedtodivertpumpflowtotank(thesamewayasaregularreliefvalve)Notpilotedfromtheinletport,pilotedfromaremotesourceAllowapumptodischargetothetankessentiallyzeropressureaslongaspilotpressureismaintained,Pressurecontrolvalves,Relief,Sequence,Unloading,Directoperated,Slidingspool,Sequencevalves(directoperated),Pressurecontrolvalves,Relief,Sequence,Unloading,Directoperated,Slidingspool,Sequencevalves(pilotoperated),Pressurecontrolvalves,Relief,Sequence,Unloading,Directoperated,Slidingspool,Sequencevalves(pilotoperated),Pressurecontrolvalves,Relief,Sequence,Unloading,Directoperated,Slidingspool,Sequencevalves,Pressurecontrolvalves,Relief,Sequence,Unloading,Directoperated,Slidingspool,Sequencevalves,Pressurecontrolvalves,Relief,Pressure-reducing,Sequence,Unloading,Directoperated,Slidingspool,Sequencevalves,NormallyclosedDesignedtocauseahydraulicsystemtooperatedinapressuresequenceOutletportispressurizedExternaldrainisrequired,Unloading,Counterbalancevalves(平衡阀),Checkvalves,Pressurecontrolvalves,Relief,Pressure-reducing,Sequence,Unloading,Directoperated,Slidingspool,Counterbalancevalves,ConsistofasequencevalveandacheckvalveMaintaincontrolofaverticalcylindertopreventitfromdescendingduetogravityThepressuresettingissomewhathigherthanisnecessarytopreventthecylinderloadfromfalling,Pressure-reducingvalves,Pressure-reducingvalves(directoperated),Pressure-reducingvalves(directoperated),Pressure-reducingvalves(directoperated),Pressure-reducingvalves(pilotoperated),Pressurecontrolvalves,Relief,Pressure-reducing,Sequence,Unloading,Directoperated,Slidingspool,Pressure-reducingvalves,NormallyopenCannormallybesetforanydesireddownstreampressureOncethevalveisset,thereducedpressurewillbemaintainedregardlessofchangesinsupplypressureandthesystemload,Pressurecontrolvalves,Relief,Pressure-reducing,Sequence,Unloading,Directoperated,Pilotoperated,Slidingspool,Poppet,Relief,Pressure-reducing,Sequence,Unloading,Directoperated,Pilotoperated,Pressurecontrolvalves,Relief,Pressure-reducing,Sequence,Unloading,Directoperated,Slidingspool,Flowcontrolvalves,UsedtoregulatethespeedofhydraulicactuatorsCha