自力式控制阀工作原理

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原文：
（1）孔板流量计——导阀——主阀原理。主阀前设置一个流量孔板，导阀感测、比较孔板前后压力差，如压力差大于设定压差，意味着流量超过设定流量，导阀控制主阀做关阀动作。如感测压差小于设定压差，则意味着流量小于设定流量，导阀控制主阀开阀动作。导阀上的设定压差可调，调大调小设定压差，可以调大调小设定流量。由于孔板流量计的流量压差对应关系受到前流态影响极重，如果要求流量精度达到10%，则必须阀前有10d以上的直管段，而这一点工程实际中极难保障。另外这种阀出厂后的流量可调范围很小，在保持流量精度的前提下，流量可调比不会超过2：1。（2）“Kv·=常数”原理，自由弹簧和感压膜构成阀门开关动力系统△P/S=εL S—感膜工作面积，ε—弹簧的胡克系数，L—阀行程由此可知阀门的每一个行程位置决定△P值的大小，如果阀行程位的Kv与成反比，则G=Kv· 是恒定值。这一原理的阀最初做成流量不可调的流量限制器，近年生产的流量可调式一种是做成多管通道，通过堵管调整设定流量；另一种是用一手动阀改变自力阀 Kv与行程的关系，但这种办法很难保证Kv与在每一调整位置的反比关系，造成调整位的流量控制精度不高。另外有的产品用波纹管制作感压膜和自由弹簧的一体化产品，由于不锈钢波纹管处在流动死区，在水中氯离子含量较高时，极易产生腐蚀。（3）自力式压差控制阀与手动调节阀阀组原理。这种原理是现在国产流量控制阀最广泛采用的。手动调节阀的每一个开度位置对应一个Kv值，由自力式压差控制阀控制手动调节阀前的压差不变，则G=Kv· 不变，改变流量时只需调整手动调节阀的Kv值。这种阀的流量控制精度决定于压差控制阀精度，压差 △P=N/S N——弹簧力 S——感压膜工作面积弹簧力在自力阀的行程内会有变化，但使 H/△L=1/10 H——自力阀最大位移行程 △L——弹簧的预压缩量则△P的变化仅为±5%，流量精度可达3%。这咱自力式流量控制阀的缺点在于阀门有最小工作压差的要求，一般产品要求最小工作压差20KPa，如果安装在最不利回路上，势必要求循环泵多增加2米水柱的工作扬程，所以应采取近端安装，远端不安的办法。用户离热源距离大于供热半径的80%时就不宜安装这种自力式流量控制阀。（4）用自力式压差控制阀直接控制流量户内阻力系数S，在平均供热的前提下是不变值，户内设计流量G，△P=SG2,通过控制户内供回水压差，一样可以控制循环流量，调节控制压差就可调节循环流量。用这种办法调控流量，只是必须借助便携式流量测试仪器如超声波流量计。这种方式对于远端用户，阀门不会增加消耗压头。

“Self-control valve works ”是由中国控制阀网提供的阀门行业新闻，译文仅供参考。另外，中国控制阀网还提供相关产品搜索：自动控制阀、水力控制阀、执行器和附件、更多控制阀产品、控制阀价格等。

译文：
Self-control valve works (1) Orifice Flowmeter - the pilot valve - the main valve principle. Set before a main valve flow orifice, the pilot valve sensing, comparing before and after the orifice pressure difference, such as the pressure difference is greater than the set pressure, mean flow rate exceeds a set flow rate, the pilot valve control valve off the main valve to do the action. Such as a sense of pressure measurement is less than the set pressure, the flow rate is less than the mean flow, the pilot valve controlling the main valve to open the valve action. Set the pressure on the pilot valve is adjustable, set the tone major, small pressure difference, can set the tone major, a small flow. As the differential pressure flow meter orifice by the correspondence between the state before the impact of heavy traffic, if the required flow rate of 10% accuracy, you must first have the valve above the 10d straight pipe, and this works in practice extremely difficult to protect. Also, such a flow after the valve is factory adjustable range is very small, while maintaining the flow accuracy of the premise, adjustable flow will not exceed 2:1 ratio. (2) "Kv · = constant" principle, a sense of freedom laminated springs and valve switching power systems constitute △ P / S = εL S-sense of film work area, ε-Hook spring coefficient, L-valve stroke It can be seen every stroke of the valve position determines the size of △ P value, if the valve travel position of the Kv and inversely proportional to the G = Kv · is a constant value. The valve was originally made of this principle is not adjustable flow rate limiter flow, the flow of production in recent years, one is made of multi-adjustable tube channel, adjust the settings by plugging flow; other is to use a manual valve to change the self-valve Kv and the itinerary of the relationship, but this approach is difficult to ensure Kv and adjust the position of each of the inverse relationship, resulting in adjusted position of the flow control accuracy is not high. In addition, some products with a sense of laminated corrugated pipe production integration of products and free spring, stainless steel bellows in the flow as dead in the water and chloride ion content is high, easy to produce corrosion. (3) Self-pressure control valve and manual valve control valve principle. This principle is now the most widely-made flow control valve used. Each manual valve opening position corresponds to a Kv value, by the self-operated pressure control valve manual control valve before the pressure constant, G = Kv · the same, just change the flow control valve for manual adjustment Kv value. This valve flow control accuracy depends on the accuracy of the pressure control valve, pressure △ P = N / S N - spring force S - a sense of laminated work area Spring force in self-valve stroke there will be changes, but the H / △ L = 1 / 10 H - Self-valve maximum displacement stroke △ L - spring pre-compression △ P is the change of only ± 5%, flow accuracy up to 3%. It argues self-operated flow control valve disadvantage is the minimum working pressure valve requirements, general product requires a minimum working pressure 20KPa, if installed in the most unfavorable loop, will require more circulation pump work increased by 2 m water column head, Therefore, installation should be taken to the proximal and distal disturbing way. User distance from the heat source radius greater than 80% of heating should not be installed on this self-operated flow control valve. (4) Self-pressure control valve with direct control flow Indoor drag coefficient S, the average heating value of the premise is the same, indoor design flow G, △ P = SG2, by controlling the indoor supply and return water pressure, the same can control the circulation flow, adjust the control pressure on the Adjustable circular flow. In this way control flow, but requires the help of portable test instruments such as ultrasonic flow meter. In this way for remote users, the valve will not increase the consumption of pressure head.

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原文来源：http://www.1kongzhifa.com/

2012-01-18 07:50