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1、,PROPORTIONAL VALVES-BASIC PRINCIPLES,Copyright Eaton Hydraulics 2000,Steve Skinner,Eaton Hydraulics,Havant,UK,比例阀基本原理,BASIC SYSTEM,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,BASIC SYSTEM,当电磁阀得电时，油缸活塞将伸出和回缩,其速
2、度由流量控制阀确定，而电磁阀不具有控制速度的能力。,BASIC SYSTEM,A three position solenoid valve can:-extend the cylinder,BASIC SYSTEM,A three position solenoid valve can:-extend the cylinder-retract the cylinder,BASIC SYSTEM,A three position solenoid valve can:-extend the cylinder-retract the cylinder-stop the cylinder,因此电磁
3、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。and in the other position it is switched on but there are no intermediate states.,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,another type of switch can be used for controlling a light bulb known as a dimmer switch.,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In this
4、case,the switch can be turned to any position between fully off and fully on to vary the brightness of the bulb.,In this case,the switch can be turned to any position between fully off and fully on to vary the brightness of the bulb.,In this case,the switch can be turned to any position between full
5、y off and fully on to vary the brightness of the bulb.,In this case,the switch can be turned to any position between fully off and fully on to vary the brightness of the bulb.,In this case,the switch can be turned to any position between fully off and fully on to vary the brightness of the bulb.,In
6、this case,the switch can be turned to any position between fully off and fully on to vary the brightness of the bulb.,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。In this case,the switch can be turned to any position between fully off and fully on to vary the brightness of the bulb.,In this case,the switch c
7、an be turned to any position between fully off and fully on to vary the brightness of the bulb.,BASIC SYSTEM,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。A proportional directional valve can be thought of as the dimmer switch equivalent of an electric
8、al switch.,BASIC SYSTEM,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。So in effect the proportional directional valve is acting as both a directional valve and a flow control valve.,SWITCHING SOLENOID VALVE,一个传统的电磁阀能够被认为是一个简单的开关阀。A conventional solenoid valve can be thought of as a simple switching valve.它可以被一些只有简单电流通断
9、的开关的电设备来控制It is controlled by some form of electrical device which simply switches the electrical current on or off.,SWITCHING SOLENOID VALVE,A conventional solenoid valve can be thought of as a simple switching valve.It is controlled by some form of electrical device which simply switches the elect
10、rical current on or off.,SWITCHING SOLENOID VALVE,A conventional solenoid valve can be thought of as a simple switching valve.It is controlled by some form of electrical device which simply switches the electrical current on or off.,PROPORTIONAL VALVE,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。A proportional direc
11、tional valve however will be controlled by an electrical device more like a dimmer switch.,PROPORTIONAL VALVE,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。By varying the current to either solenoid,the amount of spool movement can be varied and hence the amount of flow through the valve can be controlled.
12、,PROPORTIONAL VALVE,By varying the current to either solenoid,the amount of spool movement can be varied and hence the amount of flow through the valve can be controlled.,PROPORTIONAL VALVE,By varying the current to either solenoid,the amount of spool movement can be varied and hence the amount of f
13、low through the valve can be controlled.,PROPORTIONAL VALVE,By varying the current to either solenoid,the amount of spool movement can be varied and hence the amount of flow through the valve can be controlled.,PROPORTIONAL VALVE,By varying the current to either solenoid,the amount of spool movement
14、 can be varied and hence the amount of flow through the valve can be controlled.,PROPORTIONAL VALVE,By varying the current to either solenoid,the amount of spool movement can be varied and hence the amount of flow through the valve can be controlled.,PROPORTIONAL SOLENOID,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，
15、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,PROPORTIONAL SOLENOID,When a voltage is applied to the coil connections,an electrical current will flow through the coil.,PROPORTIONAL SOLENOID,1)接下来，电流生成一个磁场，磁场主要集中在金属框架、电
16、机片和电枢中In turn,the electrical current creates a magnetic field which is concentrated in the metal frame,pole piece and armature.,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。There is however a gap in the magnetic circuit between the pole piece and armature so a force is created which acts to clo
17、se this gap and complete the magnetic circuit.,PROPORTIONAL SOLENOID,1)顶针连接着电磁铁和阀芯，通常移动阀芯压缩弹簧。The push-pin connects the solenoid to the valve spool and normally moves the spool against a spring.,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force created by the solenoid is determined by the strength of the
18、magnetic field which itself is proportional to the current flowing through the coil.,PROPORTIONAL SOLENOID,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。Increasing the coil current will increase the solenoid force and hence move the spool a greater amount against the spring.,PROPORTIONAL SOLENOID,Increasing the
19、 coil current will increase the solenoid force and hence move the spool a greater amount against the spring.,PROPORTIONAL SOLENOID,Increasing the coil current will increase the solenoid force and hence move the spool a greater amount against the spring.,PROPORTIONAL SOLENOID,电磁铁被设计成电磁力(F)与线圈电流(I)成线性
20、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。A further difference between a switching solenoid valve and a proportional valve is in the design of the spool.,SWITCHING SOLENOID SPOOL,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。Which would mean that to control low flow rates,the am
21、ount of spool opening required would be very small and difficult to control.,S,S,Q,PROPORTIONAL SPOOL,1)比例阀阀芯具有比较宽的边缘带有槽口的台肩。A proportional valve spool therefore has wider lands with notches cut into the edges.,S,S,Q,PROPORTIONAL SPOOL,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。So although the ma
22、ximum flow through the valve may be reduced(compared to a switching valve)low flows in particular are more easily controlled and the opening of the valve is more gradual.,1)比例阀阀芯具有比较宽的边缘带有槽口的台肩。,S,S,Q,PROPORTIONAL SPOOL,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Depending upon the maximum flow to be con
23、trolled,different spools can be fitted to a particular valve which have different shape,size or number of spool notches.,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。Proportional valves can also be used to control pressure.In this case a proportional solenoid is use
24、d to push a poppet against a seat via a spring.The greater the solenoid force the greater the pressure required to push the poppet off its seat and open the valve.,DIRECT ACTING PROPORTIONAL RELIEF VALVE,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。This provides a direct acting relief valve function but
25、 like most such valves,it is only possible to pass small flow rates through the valve.,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。Proportional valves can also be used to control pressure.In this case a proportional solenoid is used to push a poppet against a seat via a spr
26、ing.The greater the solenoid force the greater the pressure required to push the poppet off its seat and open the valve.,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To control higher flow rates,the proportional direct acting relief valve can be used as the pilot stage of a two-stage relief(or red
27、ucing valve).,TWO-STAGE PROPORTIONAL RELIEF VALVE,To control higher flow rates,the proportional direct acting relief valve can be used as the pilot stage of a two-stage relief(or reducing valve).,BENEFITS OF PROPORTIONAL SYSTEMS,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
28、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。With a proportional system however,where control valve adjustment is electronic,only low-power electrical cables need to be connected between the operators desk and the valve.,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
29、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 SOLENOID VALVE RESPONSE TIME,A further benefit of proportional valves is the ability to electronically control the speed of operation of the valve.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,SOLENOID VALVE RESPONSE TIME,Depending upon its siz
30、e and voltage supply,a conventional switching solenoid valve will have an energisation response time of approximately 15 milli-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,SOLENOID VALVE RESPONSE TIME,The de-energisation response time will be only slightly slower(typically around 25 ms
31、)since the return spring produces less force than the solenoid.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 PROPORTIONAL VALVE RESPONSE TIME,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。The speed ofmovement of a proportional valve spool however can be determined by the electronic sign
32、al fed to the valve solenoid.By gradually increasing or decreasing the the signal(known as ramping),it is possible to achieve energisation and de-energisation response times of several seconds.,1.000,S,PROPORTIONAL VALVE RESPONSE TIME,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
33、,S,PROPORTIONAL VALVE RESPONSE TIME,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,PROPORTIONAL VALVE RESPONSE TIME,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 LIFT EXAMPLE-CONVENTIONAL SYSTEM,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
34、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 LIFT EXAMPLE-CONVENTIONAL SYSTEM,.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 LIFT EXAMPLE-CONVENTIONAL SYSTEM,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
35、例-比例系统PROPORTIONAL SYSTEM,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LIFT EXAMPLE-PROPORTIONAL SYSTEM,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。The proportional valve can be opened sufficiently slowly to provide a smooth acceleration of the lift up to its maximum speed.,顶升举例-比例系统LIFT EXAMPLE-P
36、ROPORTIONAL SYSTEM,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。And likewise the deceleration can be controlled by slowing down the speed of spool movement back to the centre condition.,time,Distance,运动控制 MOTION CONTROL,因此总的来说，比例阀能够提供全部的运动控制包括：In general therefore,proportional valves are capable of providing full m
37、otion control in terms of:,time,Acceleration,Distance,MOTION CONTROL,1.A smooth and controlled acceleration of an actuator up to its maximum speed.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,MOTION CONTROL,2.Control of the actuator velocity and if necessary maintaining it constant wi
38、th varying loads.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,MOTION CONTROL,3.A smooth deceleration with minimal pressure peaks.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,MOTION CONTROL,4.By using suitable sensing devices,the proport
39、ional valve can also be used to control the actuator stopping position to high levels of accuracy.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 FORCE CONTROL,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）Proportional valves can also be used to control the force output from an actuator(for examp
40、le in press or plastic injection moulding applications)by controlling the pressure applied to the actuator.,time,Force,FORCE CONTROL,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。In such cases it is often necessary to control not only the maximum actuator pressure but also the rate at which the pressure
41、 is applied or removed.,time,Force,FORCE CONTROL,In fact the machine cycle may consist of a series of ramps and holding periods all of which can be achieved with just the one proportional valve.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,FORCE CONTROL,At the end of the machine cycle the ra
42、te at which the pressure is reduced is also critical in many processes.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。,FORCE CONTROL,Motion and force control can thus be achieved using proportional valves,and in some cases the same valve can be used for both motion and force control.This is usually referred to as
43、PQ control ie.the control of both pressure(P)and flow(Q).Furthermore,all of these control functions can be achieved using electronic inputs to the valve thus providing a simple interface to the machine controller.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
44、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。,ELECTRONIC CONTROL,电子控制,阀输入信号 VALVE INPUT SIGNAL,As described earlier,the electrical current to the solenoid of a proportional valve needs to be regulated and not just simply switched on or off as is the case with a conventional valve.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
45、用常规阀的时仅有开关通或断那样简单。,阀输入信号 VALVE INPUT SIGNAL,In theory,this could be achieved by using a dimmer switch type component(ie.a variable resistor).Practical problems such as heat generation and drift however mean that such a device would not normally be used except for the very simplest applications.在理论上这
46、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 PROPORTIONAL VALVE AMPLIFIER,Normally,the current flowing through the proportional solenoid will be controlled by some form of electronic amplifier.The amplifier itself will require a power supply(usually 12 or 24 VDC)and a com
47、mand input signal.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 PROPORTIONAL VALVE AMPLIFIER,放大器地输出（电流）由输入信号控制，所有零输入信号，电流输出也是零。The output of the amplifier(electrical current)is controlled by the input signal so with zero input the output current is also zero.,比例阀放大器 PROPORTIONAL VALVE AMPL
48、IFIER,Increasing the input signal to the amplifier results in a corresponding increase in output current to the valve solenoid.增加放大器地输入信号会导致输出到阀电磁铁的电流相应的增加。,比例阀放大器 PROPORTIONAL VALVE AMPLIFIER,Increasing the input signal to the amplifier results in a corresponding increase in output current to the v
49、alve solenoid.,比例阀放大器 PROPORTIONAL VALVE AMPLIFIER,Increasing the input signal to the amplifier results in a corresponding increase in output current to the valve solenoid.,比例阀放大器 PROPORTIONAL VALVE AMPLIFIER,The relatively large current required to drive the valve solenoid(typically 2 to 3 amps)is
50、provided by the power supply so the current required from the input signal device is very small(normally just a few milli-amps).The input control device can therefore be a simple potentiometer.一个相对较大的阀电磁铁输入电流（通常2到3安培）是由电源提供的，所有输入装置的电流要求非常小（一般仅有几毫安），因此输入控制装置可以是一个简单的电位计。,比例阀放大器 PROPORTIONAL VALVE AMPL
