JPH1163254A - Diaphragm valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diaphragm valve capable of regulating the fluid flow rate therethrough finely with higher controllability and regulating the fluid flow rate automatically to a target flow rate with accuracy while making the most of the qualities as a diaphragm valve. SOLUTION: A diaphragm valve defines, on the front side of a diaphragm 3 displaceable to the front or back by means of a valve stem 4, a fluid passage adapted to open or close upon such displacement of the diaphragm 3. The valve has a pressure regulating chamber S defined on the back side of the diaphragm 3 and a pressure regulating means to regulate the pressure in the chamber S. This pressure regulating means comprises a sensor 13 for detecting the flow rate of fluid, a pressurized-air feed line 11 for leading pressurized air, and a control valve 12 for controlling the air pressure introduced into the chamber S from the feed line 11 on the basis of detection signals the sensor 13 outputs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm valve capable of finely adjusting a flow rate.

[0002]

2. Description of the Related Art Conventionally, a diaphragm valve is, for example,
It is widely used in sawmills, water purification plants, steel mills, chemical factories, food factories, pharmaceutical factories, and processing lines using oxides and the like. The reason is that since the diaphragm is an elastic body, there is no leakage at the time of closing the flow path, and the diaphragm is suitable for opening and closing the flow path of a corrosive or highly viscous fluid.

FIGS. 2 to 4 show an example of a conventional diaphragm valve. FIG. 2 is a cross-sectional view when the valve is fully closed, FIG. 3 is a cross-sectional view when the valve is open, and FIG. 4 is an enlarged view of an IV circle portion in FIG. It is. In these figures, 1 is a main body, 2 is an upper lid, and a diaphragm 3 made of rubber or Teflon (trade name) is provided between these connecting surfaces.
Is sandwiched as a valve body. The main body 1 is formed with a weir 1A facing the front side (lower side in the figure) of the diaphragm 3 and passes between the weir 1A and the diaphragm 3 and between the inflow port 1B and the outflow port 1C. A fluid flow path is formed. A lower end of a valve stem 4 is connected to a back side (an upper surface side in the figure) of the diaphragm 3 via a compressor 5. Connected to the vessel. The operating device moves the valve stem 4 up and down. Further, a space S located on the back side of the diaphragm 3 is formed inside the upper lid 2, and this space S is open to the atmosphere through the hole 2A.

Next, the operation will be described. The distance between the diaphragm 3 and the weir 1A of the main body 1 is adjusted by moving the valve stem 4 up and down by the operating device to displace the diaphragm 3 in the front and back directions. Then, the flow path between the inflow port 1B and the outflow port 1C is opened and closed according to the interval to control the flow rate of the fluid. FIG. 2 shows a state where the diaphragm valve is completely closed when the gap between the diaphragm 3 and the weir 1A is completely closed, and FIG. 3 shows a state where the gap between the diaphragm 3 and the weir 1A is opened by a predetermined amount. is there. In the state shown in FIG. 3, since the diaphragm 3 is deformed by the fluid pressure in the flow path, the inflow port 1B of the diaphragm 3 as shown in FIG.
The part 3A in the range A on the side (primary side) and the part 3B in the range B on the outlet 1C side (secondary side) are deformed into different shapes.

[0005]

In the conventional diaphragm valve constructed as described above, the primary portion 3A and the secondary portion 3B of the diaphragm 3 are deformed into different shapes, and the flow path is formed. Since the parts to be formed are elastic bodies such as Teflon and rubber, the flow path cannot be opened and closed with high accuracy, and fine adjustment of the flow rate cannot be performed, and a phenomenon such as hunting may occur. Due to the poor controllability of the flow rate adjustment, the rangeability is about 10: 1 to 20: 1.

[0006] The rangeability of the flow control valve is required for the flow control valve when it is necessary to control the flow rate up to the minimum flow rate Qmin even when a maximum differential pressure is generated due to a load fluctuation of a process provided with the flow control valve. Control range. The range ability inherent to the flow control valve is a ratio (Qmax: Qmin) between the controllable maximum flow rate Qmax and the minimum flow rate Qmin within a limit where the inclination of the flow rate characteristic is recognized. Usually, the flow control valve is required to have high controllability with a range ability of about 30: 1 to 50: 1. It is difficult for the above-mentioned conventional diaphragm valve to meet such a demand for high controllability.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to obtain a diaphragm valve which can be finely adjusted in flow rate and has high controllability while utilizing the features of the diaphragm valve.

Another object of the present invention is to provide a diaphragm valve capable of automatically and accurately adjusting a flow rate of a fluid to a target flow rate.

[0009]

According to a first aspect of the present invention, there is provided a diaphragm valve comprising: a pressure adjusting chamber formed on a back side of a diaphragm; and a pressure adjusting means capable of adjusting the pressure of the pressure adjusting chamber. is there.

According to a second aspect of the present invention, there is provided a diaphragm valve as a pressure adjusting means, a sensor for detecting a flow rate of a fluid flowing through a flow path, a pressurized air supply path capable of supplying pressurized air, and a detection signal of the sensor. And a control valve for controlling an air pressure introduced from the pressurized air supply passage into the pressure adjustment chamber based on the pressure.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG. In FIG. 1, the same parts as those in the conventional example of FIGS. 2 to 4 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 1, reference numeral 11 denotes a hole 2 in the upper lid 2.
A pressurized air supply path connected to A, and supplies pressurized air (instrumentation air) from a pressurized air supply source (not shown) into the space S in the upper lid 2. The space S in this example is a pressure adjustment chamber in which the internal pressure is adjusted by the pressurized air supplied through the pressurized air supply path 11. Therefore, the space S is hereinafter referred to as a pressure adjustment chamber. The pressurized air supply path 11 is provided with a control valve 12. The air pressure introduced into the adjustment chamber S is controlled. The sensor 13 is
It detects the flow rate of the fluid flowing through the diaphragm valve, and in the case of this example, is provided in a pipe 6 connected to an outlet 1C of the main body 1. The pressurized air supply path 11, the control valve 12, and the sensor 13 constitute a pressure adjusting unit capable of adjusting the pressure in the pressure adjusting chamber S.

Next, the operation will be described. Pressure adjustment chamber S
Is formed on the back side of the diaphragm 3, so that the diaphragm 3 receives the fluid pressure in the flow path from its front side and receives the internal pressure of the pressure adjusting chamber S from its back side. Therefore, the deformation condition of the diaphragm 3 is adjusted according to the internal pressure of the pressure adjustment chamber S, and the fluid flow path can be controlled to open and close with high accuracy. For example, when the valve stem 4 is operated to a predetermined position by the operating device, the pressure adjusting chamber S
By raising or lowering the internal pressure of the fluid, the flow rate of the fluid can be finely adjusted by slightly narrowing or opening the fluid flow path.

As described above, since the flow rate of the fluid can be finely adjusted according to the internal pressure of the pressure adjustment chamber S, the flow rate can be accurately adjusted to the target flow rate, and as a result, sufficient rangeability can be obtained. Will be done. At this time, the flow rate is roughly adjusted by the vertical movement of the valve stem 4 by the operating device, and the control valve 12 is controlled based on the feedback signal of the sensor 13 so that the detected flow rate of the sensor 13 matches the target flow rate with high accuracy. The internal pressure of the pressure adjustment chamber S can be automatically adjusted. As a result, the flow rate of the fluid can be automatically and accurately adjusted to the target flow rate. Further, a controller for controlling the operation device and the control valve 12 in a related manner may be provided.

[0014]

As described above, the first aspect of the present invention provides
Since it has a pressure adjusting chamber formed on the back side of the diaphragm and pressure adjusting means capable of adjusting the pressure of the pressure adjusting chamber, the flow rate can be adjusted according to the internal pressure of the pressure adjusting chamber while taking advantage of the characteristics of the diaphragm valve. Can be finely adjusted, and controllability is greatly improved.

According to a second aspect of the present invention, the flow rate of the fluid is automatically and accurately adjusted to the target flow rate by controlling the air pressure introduced into the pressure adjusting chamber based on the detection signal of the sensor for detecting the flow rate of the fluid. There is an effect that it can be adjusted.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram for explaining an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a conventional diaphragm valve when fully closed.

FIG. 3 is a cross-sectional view when a conventional diaphragm valve is opened.

FIG. 4 is an enlarged view of an IV circle portion in FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body 1A Weir 1B Inflow port 1C Outflow port 2 Upper lid 2A hole 3 Diaphragm 4 Valve stem 5 Compressor 6 Piping 11 Pressurized air supply path 12 Control valve 13 Sensor S Pressure regulation chamber

Claims (2)

[Claims] 1. A diaphragm valve having a flow path for a fluid that is opened and closed in accordance with the displacement of the diaphragm formed on the front side of the diaphragm that is displaced in the front and back directions by a valve shaft, the diaphragm being formed on the back side of the diaphragm. A pressure adjusting chamber, and a pressure adjusting means capable of adjusting the pressure of the pressure adjusting chamber. A pressure sensor configured to detect a flow rate of the fluid flowing through the flow path, a pressurized air supply path capable of supplying pressurized air, and the pressurized air based on a detection signal of the sensor. 2. The diaphragm valve according to claim 1, further comprising a control valve for controlling an air pressure introduced from the air supply passage into the pressure adjustment chamber.