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原文
Control valve fixed meaning and flow characteristics The control valve for regulating media flow, pressure and level. According to regulate parts of the signal, automatic control valve opening, so as to achieve the medium flow, pressure and level adjustment. Adjust the valve and electric control valve, pneumatic control valve and hydraulic control valve Electric control valve is the execution units in the industrial automation process control instrumentation. With the increasingly high degree of automation, industrial areas, are increasingly being used in a variety of areas of industrial production. Has obvious advantages: energy saving compared with conventional pneumatic control valve (only consumes power only when at work), environmental (carbon), quick and easy installation (no complicated pneumatic piping and pump stations). Pneumatic control valves for the power source is compressed air cylinder actuator, and with the help of the electric valve positioner, converters, solenoid valves, to secure his position valve attachment to drive the valve, switch or proportional regulator Receive industrial automation control system, control signals to adjust the flow of media channels, the pressure, temperature and other process parameters. Pneumatic control valve is characterized by simple control, fast response, and intrinsically safe, no need to re-take explosion-proof measures Automatically adjust the valve history can be traced back to the self-operated pressure regulator, which includes a ball valve with a heavy rod, the weight used to balance the spool force, resulting in some degree of regulation, another early self-reliance regulator error in the form of balanced pressure relief valve. Process of pressure pipeline received on the film chamber of the spring diaphragm regulator. Regardless of the pressure reducing valve, pressure relief valve or differential pressure relief valve after the valve pen enough to change from this base valve manufactured Cv flow capacity is one of the main parameters to select the control valve, the valve flow capacity is defined as: when the control valve fully open the valve at both ends of the differential pressure is 0.1MPa, the density of the fluid when 1g/cm3 hour flow path number of the flow control valve, known as the flow capacity, also known as the flow coefficient, expressed in units of t / h to Cv, liquid Cv value calculated. According to the flow capacity of Cv value of the size of the look-up table, you can determine the valve nominal diameter DN Control valve flow characteristics, under the conditions of the valves at both ends of the pressure remains constant, the relationship between the relative flow of the medium flows through the valve and its opening. Control valve flow characteristics are linear features, such as the percentage of properties and the parabolic nature of the three. Significance of the three fluence characteristics are as follows: (1) parabolic characteristic Flow changes in proportion to the trip two parties, generally in the middle of the linear and equal percentage characteristic features. (2) linear features (linear) The relative stroke and the relative flow of the linear characteristic into a linear relationship. Units stroke caused by changes in flow rate change is constant. Flow, flow, the relative value of small changes, traffic hours, the flow of the relative value changes. (3) the percentage of properties (logarithmic) The percentage of properties relative stroke and the relative flow is not a linear relationship between the units in each point in the trip itinerary changes caused by changes in flow and this flow is proportional to the flow percentage change is equal. The advantage is that traffic hours, traffic changes in the flow, the flow changes, which is different, with the same regulation accuracy. It can be seen from the analysis of these three characteristics, its adjust a performance perspective, to the percentage of properties for the optimal stability of its regulation, good regulating performance. Regulation performance than linear parabolic characteristic features, according to require different occasions, the selection of any flow characteristics.
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译文：
调节阀用于调节介质的流量、压力和液位。根据调节部位信号，自动控制阀门的开度，从而达到介质流量、压力和液位的调节。调节阀分电动调节阀、气动调节阀和液动调节阀等电动调节阀是工业自动化过程控制中的重要执行单元仪表。随着工业领域的自动化程度越来越高，正被越来越多的应用在各种工业生产领域中。与传统的气动调节阀相比具有明显的优点：节能（只在工作时才消耗电能），环保（无碳排放），安装快捷方便（无需复杂的气动管路和气泵工作站）。气动调节阀就是以压缩空气为动力源，以气缸为执行器，并借助于电气阀门定位器、转换器、电磁阀、保位阀等附件去驱动阀门，实现开关量或比例式调节，接收工业自动化控制系统的控制信号来完成调节管道介质的流量、压力、温度等各种工艺参数。气动调节阀的特点就是控制简单，反应快速，且本质安全，不需另外再采取防爆措施自动调节阀的历史可追溯到自力式调压阀，它包括一个带有重物杆的球形阀，重物用来平衡阀芯力，从而得到某种程度的调节，另一种早期的自力式调压阌的形式是压力平衡式调压阀。工艺过程的压力用管线接到弹簧薄膜调压阀的薄膜气室上。无论是减压阀、阀后压力式调压阀或是差压调压阀都笔够从这种基型阀门的变更而制造出来流通能力Cv是选择调节阀的主要参数之一，调节阀的流通能力的定义为：当调节阀全开时，阀两端压差为0.1MPa，流体密度为1g/cm3时，每小时流径调节阀的流量数，称为流通能力，也称流量系数，以Cv表示，单位为t/h，液体的Cv值按下式计算。根据流通能力Cv值大小查表，就可以确定调节阀的公称通径DN 调节阀的流量特性，是在阀两端压差保持恒定的条件下，介质流经调节阀的相对流量与它的开度之间关系。调节阀的流量特性有线性特性，等百分比特性及抛物线特性三种。三种注量特性的意义如下： (1)抛物线特性流量按行程的二方成比例变化，大体具有线性和等百分比特性的中间特性。 (2)线性特性(线性) 线性特性的相对行程和相对流量成直线关系。单位行程的变化所引起的流量变化是不变的。流量大时，流量相对值变化小，流量小时，则流量相对值变化大。 (3)等百分比特性(对数) 等百分比特性的相对行程和相对流量不成直线关系，在行程的每一点上单位行程变化所引起的流量的变化与此点的流量成正比，流量变化的百分比是相等的。所以它的优点是流量小时，流量变化小，流量大时，则流量变化大，也就是在不同开度上，具有相同的调节精度。从上述三种特性的分析可以看出，就其调节性能上讲，以等百分比特性为最优，其调节稳定，调节性能好。而抛物线特性又比线性特性的调节性能好，可根据使用场合的要求不同，挑选其中任何一种流量特性。

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