JPH0579606U - Pilot operated pressure reducing valve - Google Patents

Abstract

(57) [Summary] [Purpose] The purpose of the pilot operated pressure reducing valve is to minimize the effect on the secondary pressure even if there is a fluctuation in the primary pressure. [Constitution] Lower lid guide portion 3 sliding on the inner peripheral surface 4c of the main valve
The sliding gap 4d between a and the main valve 4 is made larger than the sliding gap 2c between the main valve 4 slidably fitted to the inner peripheral surface 2b of the main valve seat, and heat resistance of tetrafluoroethylene resin etc. A sealing material 24 made of synthetic resin seals between the inner peripheral surface 4c of the main valve and the guide portion 3a, and the main valve 4 is provided with a communication hole 4b.
2 in the balance chamber 25, which is separated and formed by the lower lid 3 and
Structure that introduces the secondary fluid pressure.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a pilot operated pressure reducing valve for keeping a fluid at a desired pressure under reduced pressure.

[0002]

[Prior Art]

 A conventional pilot operated pressure reducing valve will be described with reference to FIG. In the figure, 1 is a valve box having an inflow passage 1a and an outflow passage 1b, 2 is a main valve seat, and a side wall of the main valve seat 2 is provided with a communication hole 2a for forming a fluid passage. And is screwed to the valve box 1 at the communicating portion between the inflow passage 1a and the outflow passage 1b. Reference numeral 3 is a lower lid screwed to the bottom of the valve box 1, and 4 is a main valve slidably fitted on the inner peripheral surface 2b of the main valve seat 2. The upper end surface 4a is positioned so that the upper end surface 4a is seated on the main valve seat 2 by always being biased to move upward by the spring 5 arranged on the side (valve closing habit), and at the same time, the above communication is performed. The hole 2a is closed. 6 is a cylinder fitted in the valve housing 1 above the main valve seat 2, 7 is a piston fitted in the cylinder 6 slidably in the vertical direction, and the lower end surface of the piston 7 A piston rod 7a protruding from the cylinder 6 penetrates the bottom wall of the cylinder 6 so as to move back and forth and contacts the upper end surface 4a of the main valve 4.

Reference numeral 8 denotes an upper lid fixed to the upper end surface of the valve box 1 by a bolt or the like (not shown). The upper lid 8 has a screw hole in a direction orthogonal to the axial direction of the main valve 4. 8a and a diaphragm chamber 8b are formed. Reference numeral 9 denotes a pilot valve seat which is screwed into the screw hole 8a and has a through hole 9a formed in the center thereof. 10 is a conical pilot valve which operates to open and close one opening of the through hole 9a. The lid of the pilot valve chamber 11a, 12 is a spring that pressurizes the pilot valve 10 to seat it on the pilot valve seat 9, and 13 is a strainer.

Further, 14 is a protective cylinder for holding the adjusting spring 15 fixed to the peripheral portion of the diaphragm chamber 8 b, 16 is a spring receiver carried by an adjusting screw 17, 18 is a fixing nut, 19 Is a diaphragm which is sandwiched and fixed by the upper lid 8 and the protective cylinder 14 and is given a habit of moving to the left (curving) in the figure by the elasticity of the adjusting spring 15 via the diaphragm receiver 20.

Reference numeral 21 denotes a primary side fluid passage that connects the inflow passage 1 a and the pilot valve chamber 11 a, and 22 denotes a primary side fluid whose flow rate is controlled by the pilot valve 10 to one end of the piston 7. The control-use primary side fluid passage 23, which is introduced into the formed piston chamber 7a, is a secondary side fluid pressure detection hole (hereinafter, simply referred to as a detection hole) which communicates the outflow passage 1b with the diaphragm chamber 8b. ..

In the pilot-operated pressure reducing valve configured as described above, first, the pressure P1 of the primary fluid (steam) in the pilot valve chamber 11a and the elasticity of the spring 12 with respect to the pilot valve 10 are shown in the figure. , The sliding portion 10a of the pilot valve 10 is always in contact with the diaphragm 19 by acting in the right direction. Therefore, the movement of the diaphragm 19 is transmitted to the pilot valve 10 from the right side through the sliding portion 10a. It

On the other hand, the diaphragm 19, which is given the habit of moving to the left (curving) by the elasticity of the adjusting spring 15, receives a pressing force in the right direction by the pressure P2 of the secondary fluid in the diaphragm chamber 8b. Then, the diaphragm 19 is bent due to the difference between these two pressing forces, the pilot valve 10 is opened, and the pilot valve 10 is opened and maintained at a desired opening degree and stands still. The opening of the pilot valve 10 can be appropriately adjusted by operating the adjusting screw 17 to change the elasticity of the adjusting spring 15.

In this way, the primary fluid for control, which is controlled by the pilot valve 10 and flows into the piston chamber 7 a, presses the piston 7 downward, but this force acts on the lower surface of the piston 7. It acts as a valve opening force of the main valve 4 together with the pressure P2 of the secondary fluid acting on the upper end surface 4a of the main valve 4 against the pressure P2 of the secondary fluid. On the other hand, the pressure P1 of the primary fluid and the elastic force of the spring 5 act upward on the main valve 4 to become a valve closing force.

The main valve 4 stops at such a position where the valve opening force and the valve closing force are balanced and operates so as to keep the pressure P2 of the secondary fluid constant. The opening degree, that is, the magnitude of the pressure P2 of the secondary fluid is determined by the pressure of the control primary fluid. Further, the determined pressure P2 of the secondary fluid is fed back to the diaphragm chamber 8b through the detection hole 23, whereby the valve opening force of the pilot valve 10 is set to a predetermined magnitude set in the adjusting spring 15. The pressure of the primary fluid for control is controlled so that

[0010]

[Problems to be solved by the device]

The pilot-operated pressure reducing valve for steam functions to keep the fluid pressure supplied to these even if the steam usage of the end equipment changes, and automatically with a slight control deviation with respect to the set target pressure. Pressure control. However, the disturbance applied to the pressure reducing valve is not only the change in the amount used, but also the change in the primary-side steam pressure supplied to the pressure reducing valve. For example, the steam generated in the boiler is used by many devices including the pressure reducing valve, but the steam pressure sent from the boiler may fluctuate significantly depending on the total amount of steam used. Even at this time, when the pressure on the secondary side that is being controlled by the pressure reducing valve fluctuates, control is performed by changing the valve opening. Generally, however, when the primary side pressure change is 1 kgf / cm ² , the secondary side is changed. The pressure fluctuates about 0.1 kgf / cm ² .

Depending on the application of the equipment, precise vapor pressure may be required. In such a case, conventionally, two pressure reducing valves were used in series to reduce the pressure to two stages, and the first pressure reducing valve was used. By absorbing the fluctuation of the primary side pressure, the fluctuation of the inlet pressure of the second-stage pressure reducing valve was suppressed to as small as possible, and the pressure was maintained while maintaining a precise constant pressure.

In view of the above situation, it is an object of the present invention to minimize the influence on the secondary pressure even when the primary pressure fluctuates.

[0013]

[Means for Solving the Problems]

 In the pilot operated pressure reducing valve, as described above, the primary side fluid pressure P1 and the elastic force of the spring 5 act upward on the main valve 4 to form a valve closing force. That is, the primary side fluid pressure P1 acts on the lower surface of the main valve, and its acting force in the upward direction is given by the acting force = A × (, where A is the inner diameter area of the outlet inner peripheral surface 2d of the valve seat 2). (Primary pressure-secondary pressure). From this theory, it can be seen that the smaller A is, the smaller the acting force on the main valve 4 is. That is, if A is made as small as possible, the valve closing force acting on the main valve 4 does not change so much even if the primary side fluid pressure fluctuates, and the influence on the secondary side pressure being controlled is suppressed. You can However, simply reducing A causes another problem that the maximum flow rate of the pressure reducing valve is restricted.

Therefore, in the present invention, the main valve is slidably fitted to the inner peripheral surface of the main valve seat, and the guide portion of the lower lid is slidably fitted to the inner peripheral surface of the main valve. The sliding gap is made larger than the sliding gap between the inner peripheral surface of the main valve seat and the main valve, and a sealant made of a heat-resistant synthetic resin such as tetrafluoroethylene resin is used to seal the inside of the main valve and the guide portion. Further, the main valve is provided with a communication hole to introduce the secondary side pressure into the balance chamber formed and isolated by the main valve and the lower lid.

[0015]

[Action]

 Since the present invention is configured as described above, the unbalanced force by which the primary fluid flowing into the valve box 1 pushes the main valve 4 in the valve closing direction is caused by the inner diameter of the main valve seat and the seal inside the main valve. -It occurs in the cross-sectional area of the circular ring part that is composed of the sliding diameter (the area of this sliding diameter is B). Therefore, the acting force of the primary side fluid pressure in the upward direction on the main valve 4 is as follows: acting force = (A−B) × (primary side pressure−secondary side pressure) By setting the seal / sliding diameter (area B) of the surface 4c close to the inner diameter of the main valve seat outlet 2d (area A), the unbalanced force can be greatly reduced and the primary Changes in the unbalanced force that pushes the main valve toward the valve closing direction due to pressure fluctuations in the side fluid pressure are reduced, and as a result, changes in the secondary pressure controlled by the pressure reducing valve can be minimized. Becomes

The main valve 4 is slidably mounted on the inner peripheral surface 2b of the main valve seat, and the lower lid guide portion slides on the inner peripheral surface 4c of the main valve. Since the dynamic clearance 4d is larger than the sliding clearance 2c between the inner peripheral surface 2b of the main valve seat and the main valve 4, the main valve 4 is held concentric with the vertical center axis of the pressure reducing valve when the main valve 4 moves up and down. The sliding / guide action for moving is performed only by sliding the metal surfaces of the inner surface 2b of the main valve seat and the main valve 4, and the metal of the inner surface 4c of the main valve and the surface of the lower lid guide portion 3a. There is no contact between them. Therefore, the heat-resistant synthetic resin sealing material 24 seals the sliding gap between the inner peripheral surface 2b of the main valve and the lower lid guide 3a. There is no worry of deterioration.

[0017]

【Example】

 An embodiment of the pilot operated pressure reducing valve structure according to the present invention will be described below with reference to FIG. The same reference numerals are given to the same members as those in FIG. 4 showing the conventional example. Reference numeral 4 denotes a main valve which is slidably fitted on the inner peripheral surface 2b of the main valve seat 2, and which is always moved upward by the elastic force of a spring 5 arranged below the main valve 4. The upper end surface 4a is biased so that the upper end surface 4a is positioned so as to be seated on the main valve seat 2 (valve closing behavior), and at the same time, the side wall of the main valve seat 2 is bored to form a fluid passage. The formed communication hole 2a is closed.

A seal member 24 made of a heat-resistant synthetic resin such as tetrafluoroethylene resin is provided on the lower inner peripheral surface 4c of the main valve 4, and a communication hole communicating with the secondary side is provided on the upper part of the main valve 4. 4b is drilled. Reference numeral 3 is a lower lid screwed to the bottom of the valve box 1. A cylindrical guide portion 3a, which is erected from the center of the bottom portion of the lower lid 3, is slidably fitted on the inner peripheral surface 4c of the main valve 4, and is isolated from the primary side fluid pressure by the sealing material 24. To form a balanced chamber 25. The sliding gap 4d between the lower lid guide portion 3a and the inner peripheral surface 4c of the main valve 4 is larger than the sliding gap 2c between the inner peripheral surface 2b of the main valve seat and the main valve 4.

FIG. 3 shows the results of a comparative experiment using the pilot operated pressure reducing valve according to the present invention and a conventional pilot operated pressure reducing valve. When the primary pressure is 3 kgf / cm ² , the secondary pressure is The following shows the secondary side pressure fluctuation characteristics of the pressure reducing valve with respect to changes in the primary side steam pressure when the side pressure is set to ² kgf / cm ² . When the primary pressure is 7 kgf / cm ² increased to 10 kgf / cm ² from 3 kgf / cm ^2, in the conventional vacuum valve has been Tsu name to 1.3kgf / cm ² 0.7kgf / cm ² fluctuates, the present invention The pressure reducing valve according to No. ^{2 produced} only a slight pressure fluctuation of 0.1 kgf / cm ² or less and could maintain 1.9 kgf / cm ² or more.

[0020]

[Effect of the device]

 Since the pilot operated pressure reducing valve according to the present invention is configured as described above, the primary fluid flowing into the valve box 1 is blocked by the sealing material 24 on the inner peripheral surface 4c of the main valve 4, The secondary side fluid pressure is introduced into the balance chamber 25 provided below through the communication hole 4b. As a result, the unbalanced force of the primary side fluid pressure pushing the main valve 4 toward the valve closing direction consists of the inner diameter of the valve seat (area A) and the seal / sliding diameter of the inner circumference of the main valve (area B). Although it occurs in the area of the circular ring portion, the imbalance force can be significantly reduced by making the seal / sliding diameter inside the main valve 4 close to the inner diameter of the valve seat outlet. Therefore, the change in the unbalanced force that pushes up the main valve 4 in the valve closing direction due to the fluctuation of the primary fluid pressure is reduced, and the fluctuation effect on the secondary fluid pressure controlled by the pressure reducing valve is minimized. It can be stopped for as long as possible.

As described above, according to the pilot operated pressure reducing valve of the present invention, it is possible to supply a precise constant pressure even if there is a large change in the primary side steam pressure supplied to the pressure reducing valve. It is possible to manufacture an ideal pilot operated decompression valve for steam that automatically controls the pressure with a slight control deviation against the set pressure even when the amount changes and the primary side steam pressure changes. ..

In addition, the guide / sliding surface of the main valve is separated from the seal / sliding surface, and since the seal / sliding surface does not come into metal contact, the sealing performance of the seal is not impaired and it can withstand long-term use. You can In addition, the equipment cost is high and the two-stage depressurization method that requires a large installation space is not required.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a pilot operated pressure reducing valve according to the present invention.

FIG. 2 is an enlarged vertical cross-sectional view of a main part showing the configuration of a main valve part.

FIG. 3 is a characteristic diagram showing fluctuations in the secondary side fluid pressure of the pressure reducing valve with respect to changes in the primary side fluid pressure.

FIG. 4 is a vertical cross-sectional view of a conventional pilot operated pressure reducing valve.

[Explanation of symbols]

 1 valve box 2 main valve seat 2a conduction hole 2b inner peripheral surface 2c sliding gap 2d outlet inner peripheral surface 3 lower lid 3a guide part 4 main valve 4a upper end surface 4b communication hole 4c inner peripheral surface 4d sliding gap 5 spring 6 cylinder 7 Piston 8 Upper lid 9 Pilot valve seat 9a Through hole 10 Pilot valve 11 Lid 12 Spring 13 Strainer 14 Protective cylinder 15 Adjusting spring 19 Diaphragm 20 Diaphragm receiver 21 Primary fluid passage 22 Control primary fluid passage 23 Secondary side Fluid pressure detection hole 24 Seal material 25 Balance chamber P1 Primary side fluid pressure P2 Secondary side fluid pressure

Claims (1)

[Scope of utility model registration request] 1. A piston having a main valve seat having a hole forming a fluid passage for communication with the main valve and a side wall thereof, the opening / closing of the main valve being controlled by a primary side fluid pressure controlled by a pilot valve. In the provided pilot operated pressure reducing valve for steam, the main valve is slidably fitted to the inner peripheral surface of the main valve seat, and the guide portion of the lower lid is also slidably fitted to the inner peripheral surface of the main valve. At the same time, the sliding gap is made larger than the sliding gap between the inner peripheral surface of the main valve seat and the main valve, and the inside of the main valve and the guide portion are sealed with a heat-resistant synthetic resin sealing material such as tetrafluoroethylene resin. Then
Further, the pilot operated pressure reducing valve is characterized in that a communication hole is provided in the main valve to introduce a secondary side pressure into a balance chamber formed and isolated by the main valve and a lower lid.