液压油路电磁阀工作原理 教育学习

,PROPORTIONALVALVES-BASICPRINCIPLES,CopyrightEatonHydraulics2000,SteveSkinner,EatonHydraulics,Havant,UK,比例阀基本原理,BASICSYSTEM,1)一般认为一个简单的液压系统由油箱（A）、电动机（B）、泵（C）、溢流阀（D）、过滤器（E）、流量控制阀（F）、方向控制阀（G）、和油缸（H）组成。,2)油缸的运动是由流量控制阀（确定运动的速度）和方向控制阀（油缸运动的方向）控制。,A,B,C,D,E,F,H,G,BASICSYSTEM,当电磁阀得电时，油缸活塞将伸出和回缩,其速度由流量控制阀确定，而电磁阀不具有控制速度的能力。,BASICSYSTEM,Athreepositionsolenoidvalvecan:-extendthecylinder,BASICSYSTEM,Athreepositionsolenoidvalvecan:-extendthecylinder-retractthecylinder,BASICSYSTEM,Athreepositionsolenoidvalvecan:-extendthecylinder-retractthecylinder-stopthecylinder,因此电磁阀的动作非常象一个电路中的开关在此位置灯是关闭状态.,.在另外一个位置是开启状态，而没有中间状态。andintheotherpositionitisswitchedonbuttherearenointermediatestates.,然而众所周知，另一种形式的开关能够用来控制灯泡，调光开关However,anothertypeofswitchcanbeusedforcontrollingalightbulbknownasadimmerswitch.,在这个例子中，这个开关能够被转到全开和全关的任一位置，来调整灯泡的亮度Inthiscase,theswitchcanbeturnedtoanypositionbetweenfullyoffandfullyontovarythebrightnessofthebulb.,Inthiscase,theswitchcanbeturnedtoanypositionbetweenfullyoffandfullyontovarythebrightnessofthebulb.,Inthiscase,theswitchcanbeturnedtoanypositionbetweenfullyoffandfullyontovarythebrightnessofthebulb.,Inthiscase,theswitchcanbeturnedtoanypositionbetweenfullyoffandfullyontovarythebrightnessofthebulb.,Inthiscase,theswitchcanbeturnedtoanypositionbetweenfullyoffandfullyontovarythebrightnessofthebulb.,Inthiscase,theswitchcanbeturnedtoanypositionbetweenfullyoffandfullyontovarythebrightnessofthebulb.,在这个例子中，这个开关能够被转到全开和全关的任一位置，来调整灯泡的亮度。Inthiscase,theswitchcanbeturnedtoanypositionbetweenfullyoffandfullyontovarythebrightnessofthebulb.,Inthiscase,theswitchcanbeturnedtoanypositionbetweenfullyoffandfullyontovarythebrightnessofthebulb.,BASICSYSTEM,2)阀芯能够移动到在任一位置，而不仅仅是三个不连续的位置。阀芯在离开中位的方向仍然确定油缸运动的方向，但阀芯离开中位的距离控制活塞的速度。,1)比例方向阀能够被看作与调光开关具有同样功能。Aproportionaldirectionalvalvecanbethoughtofasthedimmerswitchequivalentofanelectricalswitch.,BASICSYSTEM,于是在实际上比例阀可以同时作为方向阀和流量阀来使用。Soineffecttheproportionaldirectionalvalveisactingasbothadirectionalvalveandaflowcontrolvalve.,SWITCHINGSOLENOIDVALVE,一个传统的电磁阀能够被认为是一个简单的开关阀。Aconventionalsolenoidvalvecanbethoughtofasasimpleswitchingvalve.它可以被一些只有简单电流通断的开关的电设备来控制Itiscontrolledbysomeformofelectricaldevicewhichsimplyswitchestheelectricalcurrentonoroff.,SWITCHINGSOLENOIDVALVE,Aconventionalsolenoidvalvecanbethoughtofasasimpleswitchingvalve.Itiscontrolledbysomeformofelectricaldevicewhichsimplyswitchestheelectricalcurrentonoroff.,SWITCHINGSOLENOIDVALVE,Aconventionalsolenoidvalvecanbethoughtofasasimpleswitchingvalve.Itiscontrolledbysomeformofelectricaldevicewhichsimplyswitchestheelectricalcurrentonoroff.,PROPORTIONALVALVE,一个比例方向阀是由与一个与调光开关非常象的电设备控制的。Aproportionaldirectionalvalvehoweverwillbecontrolledbyanelectricaldevicemorelikeadimmerswitch.,PROPORTIONALVALVE,通过改变两个之一电磁铁的电流，阀芯移动的位移能够被改变，因此控制了通过阀的流量。Byvaryingthecurrenttoeithersolenoid,theamountofspoolmovementcanbevariedandhencetheamountofflowthroughthevalvecanbecontrolled.,PROPORTIONALVALVE,Byvaryingthecurrenttoeithersolenoid,theamountofspoolmovementcanbevariedandhencetheamountofflowthroughthevalvecanbecontrolled.,PROPORTIONALVALVE,Byvaryingthecurrenttoeithersolenoid,theamountofspoolmovementcanbevariedandhencetheamountofflowthroughthevalvecanbecontrolled.,PROPORTIONALVALVE,Byvaryingthecurrenttoeithersolenoid,theamountofspoolmovementcanbevariedandhencetheamountofflowthroughthevalvecanbecontrolled.,PROPORTIONALVALVE,Byvaryingthecurrenttoeithersolenoid,theamountofspoolmovementcanbevariedandhencetheamountofflowthroughthevalvecanbecontrolled.,PROPORTIONALVALVE,Byvaryingthecurrenttoeithersolenoid,theamountofspoolmovementcanbevariedandhencetheamountofflowthroughthevalvecanbecontrolled.,PROPORTIONALSOLENOID,因此不像传统的电磁阀，通过比例阀线圈的电流需要被调整，而不仅仅是开关式的通断。比例阀电磁铁的结构与开关式电磁铁是相似的。电磁铁包括:-线圈(A)-框架(B)-电枢(C)-电极片(D)-顶针(E)电枢被包在一个芯轴管（F）中。(同时全部的总成经常被压进一个树脂塑料的外罩（G）中）,A,B,C,D,F,G,E,PROPORTIONALSOLENOID,Whenavoltageisappliedtothecoilconnections,anelectricalcurrentwillflowthroughthecoil.,PROPORTIONALSOLENOID,1)接下来，电流生成一个磁场，磁场主要集中在金属框架、电机片和电枢中Inturn,theelectricalcurrentcreatesamagneticfieldwhichisconcentratedinthemetalframe,polepieceandarmature.,2)然而在磁回路的电机片和电枢之间有一个间隙，于是产生一个力，其作用是关闭这个间隙以完成这个磁回路。Thereishoweveragapinthemagneticcircuitbetweenthepolepieceandarmaturesoaforceiscreatedwhichactstoclosethisgapandcompletethemagneticcircuit.,PROPORTIONALSOLENOID,1)顶针连接着电磁铁和阀芯，通常移动阀芯压缩弹簧。Thepush-pinconnectsthesolenoidtothevalvespoolandnormallymovesthespoolagainstaspring.,2)电磁铁产生的力The大小由磁场强度决定，磁场强度与通过线圈的电流成比例forcecreatedbythesolenoidisdeterminedbythestrengthofthemagneticfieldwhichitselfisproportionaltothecurrentflowingthroughthecoil.,PROPORTIONALSOLENOID,增大线圈电流将加大电磁的力，因此推动阀芯压缩弹簧产生一个更大的位移。Increasingthecoilcurrentwillincreasethesolenoidforceandhencemovethespoolagreateramountagainstthespring.,PROPORTIONALSOLENOID,Increasingthecoilcurrentwillincreasethesolenoidforceandhencemovethespoolagreateramountagainstthespring.,PROPORTIONALSOLENOID,Increasingthecoilcurrentwillincreasethesolenoidforceandhencemovethespoolagreateramountagainstthespring.,PROPORTIONALSOLENOID,电磁铁被设计成电磁力(F)与线圈电流(I)成线性比例关系。这意味着电磁力仅与线圈电流有关。,开关电磁阀阀芯,比例阀与开关电磁阀之间的另一个区别是阀芯的设计。Afurtherdifferencebetweenaswitchingsolenoidvalveandaproportionalvalveisinthedesignofthespool.,SWITCHINGSOLENOIDSPOOL,1)对于开关阀，阀芯被设计为当阀得电时，将压降最小化。,2)这意味着，控制小流量阀开口要求非常小并且很困难。Whichwouldmeanthattocontrollowflowrates,theamountofspoolopeningrequiredwouldbeverysmallanddifficulttocontrol.,S,S,Q,PROPORTIONALSPOOL,1)比例阀阀芯具有比较宽的边缘带有槽口的台肩。Aproportionalvalvespoolthereforehaswiderlandswithnotchescutintotheedges.,S,S,Q,PROPORTIONALSPOOL,2)因此尽管通过阀的最大流量被减少了（与开关阀对照）但小流量特别容易控制，阀的开口更有规则。Soalthoughthemaximumflowthroughthevalvemaybereduced(comparedtoaswitchingvalve)lowflowsinparticulararemoreeasilycontrolledandtheopeningofthevalveismoregradual.,1)比例阀阀芯具有比较宽的边缘带有槽口的台肩。,S,S,Q,PROPORTIONALSPOOL,依据控制的最大流量，不同的阀芯能被适用于不同形状、大小或阀芯槽口的大小特定的阀Dependinguponthemaximumflowtobecontrolled,differentspoolscanbefittedtoaparticularvalvewhichhavedifferentshape,sizeornumberofspoolnotches.,直动式比例溢流阀,1)比例阀也可以被用来控制压力。在此比例电磁铁被用来推动一个锥阀芯通过一个弹簧压缩阀座。电磁力越大，推开锥阀芯离开阀座打开阀的压力要求越大。Proportionalvalvescanalsobeusedtocontrolpressure.Inthiscaseaproportionalsolenoidisusedtopushapoppetagainstaseatviaaspring.Thegreaterthesolenoidforcethegreaterthepressurerequiredtopushthepoppetoffitsseatandopenthevalve.,DIRECTACTINGPROPORTIONALRELIEFVALVE,2)这里提供一个直动式溢流阀功能，但象多数此类阀一样，只能允许一个小流量通过该阀。Thisprovidesadirectactingreliefvalvefunctionbutlikemostsuchvalves,itisonlypossibletopasssmallflowratesthroughthevalve.,1)比例阀也可以被用来控制压力。在此比例电磁铁被用来推动一个锥阀芯通过一个弹簧压缩阀座。电磁力越大，推开锥阀芯离开阀座打开阀的压力要求越大。Proportionalvalvescanalsobeusedtocontrolpressure.Inthiscaseaproportionalsolenoidisusedtopushapoppetagainstaseatviaaspring.Thegreaterthesolenoidforcethegreaterthepressurerequiredtopushthepoppetoffitsseatandopenthevalve.,两-级比例溢流阀,为控制大流量，直动式比例溢流阀能被用来作为一个两级溢流阀（或减压阀）的先导级Tocontrolhigherflowrates,theproportionaldirectactingreliefvalvecanbeusedasthepilotstageofatwo-stagerelief(orreducingvalve).,TWO-STAGEPROPORTIONALRELIEFVALVE,Tocontrolhigherflowrates,theproportionaldirectactingreliefvalvecanbeusedasthepilotstageofatwo-stagerelief(orreducingvalve).,BENEFITSOFPROPORTIONALSYSTEMS,比例系统的优点,远程控制传统系统,在常规系统中为了调整执行器的速度，流量控制阀必须安装在一个方便的或便于接近的位置，这意味着与操纵台连接的液压管路经常运行在高压下。,远程控制比例系统,对于比例系统，控制阀为电子调节，仅需要低功率的电缆连接操纵台和比例阀即可。Withaproportionalsystemhowever,wherecontrolvalveadjustmentiselectronic,onlylow-powerelectricalcablesneedtobeconnectedbetweentheoperatorsdeskandthevalve.,PLC远程控制比例系统,今天更多的是，机械控制被数字电子控制所取代，这里情况也是一样，比例阀的电子控制能力为液压系统和电子控制器之间提供一个简单的接口。,比例压力控制,使用比例方向和压力控制阀意味着机器的所有液压功能（运动和力）能被电子地控制。,电磁阀的反应时间SOLENOIDVALVERESPONSETIME,Afurtherbenefitofproportionalvalvesistheabilitytoelectronicallycontrolthespeedofoperationofthevalve.比例阀地进一步功能是电子控制阀操作速度的能力。,0.015,S,SOLENOIDVALVERESPONSETIME,Dependinguponitssizeandvoltagesupply,aconventionalswitchingsolenoidvalvewillhaveanenergisationresponsetimeofapproximately15milli-seconds.依据阀的大小和提供的电压，一个传统的开关电磁阀对于一个得电动作的反应时间是15毫秒。,0.040,S,SOLENOIDVALVERESPONSETIME,Thede-energisationresponsetimewillbeonlyslightlyslower(typicallyaround25ms)sincethereturnspringproduceslessforcethanthesolenoid.由于回程弹簧的力小于电磁铁，断电的反应时间稍慢（通常25ms左右），,S,比例阀的反应时间PROPORTIONALVALVERESPONSETIME,比例阀阀芯的运动速度能被阀电磁铁的供给电子信号确定。通过逐渐地增加或降低信号（叫做斜坡）可以完成几秒的得电和断电时间。Thespeedofmovementofaproportionalvalvespoolhowevercanbedeterminedbytheelectronicsignalfedtothevalvesolenoid.Bygraduallyincreasingordecreasingthethesignal(knownasramping),itispossibletoachieveenergisationandde-energisationresponsetimesofseveralseconds.,1.000,S,PROPORTIONALVALVERESPONSETIME,比例阀阀芯的运动速度能被阀电磁铁的供给电子信号确定。通过逐渐地增加或降低信号（叫做斜坡）可以完成几秒的得电和断电时间。,2.000,S,PROPORTIONALVALVERESPONSETIME,比例阀阀芯的运动速度能被阀电磁铁的供给电子信号确定。通过逐渐地增加或降低信号（叫做斜坡）可以完成几秒的得电和断电时间。,3.000,S,PROPORTIONALVALVERESPONSETIME,比例阀阀芯的运动速度能被阀电磁铁的供给电子信号确定。通过逐渐地增加或降低信号（叫做斜坡）可以完成几秒的得电和断电时间。,顶升举例-传统系统LIFTEXAMPLE-CONVENTIONALSYSTEM,为什么控制阀的阀芯运动速度是用用处的原因是减少系统中的震动，这可以通过控制执行器的加速和减速来完成。假设举例，一个简单的液压系统被用于宾馆中的乘客电梯操作，比较容易说明。,顶升举例-传统系统LIFTEXAMPLE-CONVENTIONALSYSTEM,.当这磁阀得电降低电梯时，阀芯将快速运动，这意味着油缸将极快地加速到其最大速度（最大速度由控制阀F的设置确定），这个突然的启动会给电梯乘客一个极不舒服的感受。,F,顶升举例-传统系统LIFTEXAMPLE-CONVENTIONALSYSTEM,同样地,当电梯达到终点时，电磁阀将非常快地关闭产生一个突然地停止，当然又是一个极不舒服地动作。在一个真正地液压系统中，由于执行器突然起停而产生地震动会产生一个高的尖峰压力，从原理上来说这将导致液压泄漏。,顶升举例-比例系统PROPORTIONALSYSTEM,如果电磁阀和流量控制阀被一个比例阀取代，不仅电梯的速度可以被电子地调整，而且电梯的起停也可以被控制。,顶升举例-比例系统LIFTEXAMPLE-PROPORTIONALSYSTEM,比例阀能够足够慢地打开以提供一个平滑加速度使电梯达到最大速度。Theproportionalvalvecanbeopenedsufficientlyslowlytoprovideasmoothaccelerationoftheliftuptoitsmaximumspeed.,顶升举例-比例系统LIFTEXAMPLE-PROPORTIONALSYSTEM,同样地，减加速度也能够被控制，使阀芯运动回中位的速度变慢。Andlikewisethedecelerationcanbecontrolledbyslowingdownthespeedofspoolmovementbacktothecentrecondition.,time,Distance,运动控制MOTIONCONTROL,因此总的来说，比例阀能够提供全部的运动控制包括：Ingeneraltherefore,proportionalvalvesarecapableofprovidingfullmotioncontrolintermsof:,time,Acceleration,Distance,MOTIONCONTROL,1.Asmoothandcontrolledaccelerationofanactuatoruptoitsmaximumspeed.一个平滑和受控的加速度，使执行器达到最大速度。,time,Acceleration,Velocity,Distance,MOTIONCONTROL,2.Controloftheactuatorvelocityandifnecessarymaintainingitconstantwithvaryingloads.执行器速度的控制，如果必要维持其在变化负载下的稳定。,time,Acceleration,Deceleration,Velocity,Distance,MOTIONCONTROL,3.Asmoothdecelerationwithminimalpressurepeaks.一个平滑的带有最小化压力峰值的减加速度,time,Position,Acceleration,Deceleration,Velocity,Distance,MOTIONCONTROL,4.Byusingsuitablesensingdevices,theproportionalvalvecanalsobeusedtocontroltheactuatorstoppingpositiontohighlevelsofaccuracy.通过使用合适的传感装置，比例阀也可以被用来高精度地控制执行器的位置,time,Force,力控制FORCECONTROL,比例阀也能够被用来控制执行器力地输出，通过控制应用于执行器上地压强。（例如在压机中或注塑机应用）Proportionalvalvescanalsobeusedtocontroltheforceoutputfromanactuator(forexampleinpressorplasticinjectionmouldingapplications)bycontrollingthepressureappliedtotheactuator.,time,Force,FORCECONTROL,在这样的实例中，不仅要求控制最大的执行器压力。而且要求控制应用中或运动中的压力等级。Insuchcasesitisoftennecessarytocontrolnotonlythemaximumactuatorpressurebutalsotherateatwhichthepressureisappliedorremoved.,time,Force,FORCECONTROL,Infactthemachinecyclemayconsistofaseriesoframpsandholdingperiodsallofwhichcanbeachievedwithjusttheoneproportionalvalve.实际上机器工作周期可能由一系列的斜坡和停止阶段组成，所有这些可以由一个比例阀来完成。,time,Force,FORCECONTROL,Attheendofthemachinecycletherateatwhichthepressureisreducedisalsocriticalinmanyprocesses.在机器运行周期后段，在很多工序中压力等级的降低也是要求很严格的。,FORCECONTROL,Motionandforcecontrolcanthusbeachievedusingproportionalvalves,andinsomecasesthesamevalvecanbeusedforbothmotionandforcecontrol.ThisisusuallyreferredtoasPQcontrolie.thecontrolofbothpressure(P)andflow(Q).Furthermore,allofthesecontrolfunctionscanbeachievedusingelectronicinputstothevalvethusprovidingasimpleinterfacetothemachinecontroller.运动和力的控制因此能够通过使用比例阀来完成，同时在某些场合同一个阀能够同时用于运动控制和力控制。这通常被称为PQ”控制，也就是说同时控制压力和流量。此外，所有这些控制功能可以使用输入到阀的电子输入信号被完成，只需通过提供的到机械控制器的简单接口。,ELECTRONICCONTROL,电子控制,阀输入信号VALVEINPUTSIGNAL,Asdescribedearlier,theelectricalcurrenttothesolenoidofaproportionalvalveneedstoberegulatedandnotjustsimplyswitchedonoroffasisthecasewithaconventionalvalve.作为简单描述，提供给比例阀电磁铁的电流需要被调节，不象应用常规阀的时仅有开关通或断那样简单。,阀输入信号VALVEINPUTSIGNAL,Intheory,thiscouldbeachievedbyusingadimmerswitchtypecomponent(ie.avariableresistor).Practicalproblemssuchasheatgenerationanddrifthowevermeanthatsuchadevicewouldnotnormallybeusedexceptfortheverysimplestapplications.在理论上这可以通过使用一个调光开关式的元件来完成（例如，一个可变电阻）。实际上由于发热和漂移这样的设备一般不被使用，除非一些最简单的应用中。,比例阀放大器PROPORTIONALVALVEAMPLIFIER,Normally,thecurrentflowingthroughtheproportionalsolenoidwillbecontrolledbysomeformofelectronicamplifier.Theamplifieritselfwillrequireapowersupply(usually12or24VDC)andacommandinputsignal.一般地，通过比例阀电磁铁地电流由一些形式地电子放大器控制。放大器要求一个电源和一个命令输入信号。,比例阀放大器PROPORTIONALVALVEAMP