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
2、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。,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
3、cylinder,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。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
4、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 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 pos
5、ition 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 fully off and fully on to vary the brightn
6、ess 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.,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
7、this case, the switch can 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
8、equivalent of an electrical 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 switc
9、hing valve.它可以被一些只有简单电流通断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
10、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 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
11、备控制的。A proportional directional 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 th
12、e 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 can be vari
13、ed 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 VALVE,By varying the current to either solenoid
14、, 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 flow through the valve can be controlled.,PROPORTIONAL SOLEN
15、OID,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,PROPORTIONAL SOLENOID,When a voltage is applied to the coil connections, an electrical current will flow through the coil.,PROPORT
16、IONAL 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 a
17、rmature so a force is created which acts to close 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 t
18、he solenoid is determined by the strength of the 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
19、 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,Increasing the coil current will increase the solenoid force and hence move the spool a greater amount against the sprin
20、g.,PROPORTIONAL SOLENOID,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。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。Whic
21、h would mean that to control low flow rates, the amount 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
22、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 maximum 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
23、、大小或阀芯槽口的大小特定的阀Depending upon the maximum flow to be controlled, 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 co
24、ntrol pressure. In this case a proportional solenoid is used 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
25、量通过该阀。This provides a direct acting relief valve function but 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 proporti
26、onal solenoid is used 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.,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
27、valve can be used as the pilot stage of a two-stage relief (or reducing 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
28、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。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 v
29、alve.,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 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
30、制阀操作速度的能力。,0.015,S,SOLENOID VALVE RESPONSE TIME,Depending upon its size 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-energi
31、sation response time will be only slightly slower (typically around 25 ms) 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
32、 a proportional valve spool however can be determined by the electronic signal 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
33、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,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 -
34、 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
35、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 p
36、rovide a smooth acceleration of the lift up to its maximum speed.,顶升举例- 比例系统LIFT EXAMPLE - PROPORTIONAL 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
37、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 motion 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
38、,MOTION CONTROL,2. Control of the actuator velocity and if necessary maintaining it constant with 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,Accelerati
39、on,Deceleration,Velocity,Distance,MOTION CONTROL,4. By using suitable sensing devices, the proportional 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
40、或注塑机应用）Proportional valves can also be used to control the force output from an actuator (for example 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
41、 necessary to control not only the maximum actuator pressure but also the rate at which the pressure 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 rate 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。,
