JPH11102225A - Pressure control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To align the deviation between the axial centers of the piston of a pressure control valve and its valve element. SOLUTION: A pressure control valve 1 integrally couples a valve element 5 and a piston 12. At the upper part of the piston 12, a pressing member 27 is attached for pressing a flange part 25 of the valve element 5. When the pressing member 27 is attached to the piston 12, an engage groove 31 having a U-shaped cross section is formed. The flange part 25 of the valve element 5 is fitted to the engage groove 31 so as to move in radial direction and assembled in the state of regulating the movement in axial line direction (vertical direction). Therefore, the piston 12 and the valve element 5 are turned into the state of being combined mutually movably in the radial direction. The piston 12 and the valve element 5 are combined so as to be mutually relatively displaced in the radial direction, the piston 12 can be displaced to the position matched with the axial center of an inner cylinder wall 41b, and the valve element 5 can be displaced to the position matched with the axial center of a valve seat 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure control valve,
In particular, the present invention relates to a pressure control valve configured to further increase the operation accuracy of a piston that drives a valve element.

[0002]

2. Description of the Related Art For example, a pipe for supplying city gas or the like is provided with a pressure control device for controlling a pressure so that a downstream secondary pressure becomes a preset target pressure.
Generally, a pressure control device includes a pilot valve that adjusts an operating pressure (also referred to as a jacket pressure) supplied to a valve driving unit in accordance with a pressure fluctuation on a downstream side, and a valve based on the operating pressure supplied to the valve driving unit. A pressure control valve that varies the opening to control the downstream secondary pressure to a target pressure.

[0003] The pressure control valve includes an "unloading type" in which an operating pressure acts on the valve body in a valve closing direction.
There is a "loading type" in which the operating pressure acts on the valve body in the valve opening direction. In the unloading type pressure control valve, the valve body is driven in the opening or closing direction by a pressure difference between the operating pressure supplied to the valve driving unit and the primary pressure acting on the valve body, and the pressure difference is controlled by the pressure difference. Variable the valve opening based on
Pressure control is performed so that the next pressure becomes a predetermined target pressure.

Further, as described above, a diaphragm driving system using a flexible diaphragm made of rubber or the like is used as a valve drive unit for driving the valve body by a pressure difference between the operating pressure and the primary pressure acting on the valve body. And a piston type in which a piston provided integrally with a valve body is slidably fitted in a pressure chamber formed in a cylinder of a valve body. In particular, in the case of a pressure control valve installed in a place where the pressure difference between the primary pressure and the secondary pressure is large, a piston type excellent in pressure resistance is adopted as a valve drive unit.

When the operating pressure is equal to the primary pressure, the valve body and the piston are displaced in the valve closing direction by the pressing force of the spring and are held at the fully closed position in contact with the valve seat of the valve body. Therefore, when the amount of gas used on the downstream side increases and the secondary pressure decreases, the pilot valve opens and the operating pressure is reduced, whereby the valve element and the piston open and the downstream side pipe line is opened. Supply gas amount increases. Further, when the operating pressure of the pressure chamber decreases to a pressure close to the secondary pressure, the valve body and the piston are displaced to the fully open position, and the amount of gas supplied to the downstream pipe further increases.

When the amount of gas used on the downstream side decreases and the secondary pressure in the downstream line increases beyond the target pressure, the operating pressure increases due to the closing operation of the pilot valve. The valve opening is reduced, and the amount of gas supplied to the downstream pipe is reduced. Therefore, the secondary pressure in the downstream pipe is maintained at the target pressure. Thus, when the secondary pressure fluctuates,
The operating pressure changes due to the opening / closing operation of the pilot valve, and the valve opening of the pressure control valve is adjusted. As a result, the secondary pressure in the downstream pipe is controlled to the target pressure.

[0007]

In the conventional pressure control valve, if the operating pressure introduced into the pressure chamber leaks, normal pressure control cannot be performed. Therefore, an O-ring as a seal member is mounted on the outer periphery of the piston. This O-ring seals between the outer periphery of the piston and the pressure chamber of the valve body.

However, conventionally, the piston is made of a softer material than the cylinder inner wall so that the inner wall of the cylinder does not wear when sliding inside the cylinder in a state where the piston and the valve body are integrally combined. Therefore, when the pressure is controlled by the sliding operation of the piston, the inner wall of the cylinder is not damaged and the piston is worn. Therefore, conventionally, the piston had to be replaced periodically.

The piston that slides on the inner wall of the cylinder has a combined structure in which a valve body having a seat portion formed thereon is fastened by a mounting bolt. Therefore, at the time of periodic inspection, only the piston that has been worn by sliding on the inner wall of the cylinder is replaced. Further, in the conventional pressure control valve, a circular concave portion in which the valve element is fitted is formed at the bottom of the piston, and the piston and the valve element are configured to be connected in a radial and axial direction without rattling. ing.

In the pressure control valve having the above-described structure, for example, if the replaced piston is eccentrically machined into a circular recess in which the valve body is fitted to the outer periphery due to a variation in machining accuracy, the axial line of the valve body may be changed. The pistons will be connected in an off-axis state. In this case, since the piston is assembled in the cylinder in an eccentric state in which the axis of the piston is shifted from the center of the inner wall of the cylinder, the piston may not slide smoothly.

Therefore, an object of the present invention is to provide a pressure control valve which solves the above-mentioned problem.

[0012]

In order to solve the above problems, the present invention has the following features. Claim 1
According to the invention described above, a valve body provided between an upstream pipe and a downstream pipe to which fluid is supplied is slidably fitted to a cylinder inner wall formed in the valve body. An annular piston that moves in a valve closing direction or a valve opening direction due to a pressure difference between an operating pressure introduced into the cylinder and a primary pressure upstream of the valve body, and one end thereof is integrally connected to the piston. A pressure control valve having a coupling element, the other end of which is displaced in a direction close to or away from a valve seat in the valve body to become a valve part that changes a valve opening degree, wherein the piston is A radially slidable connection with a connecting portion of the valve body, and a seal member provided at a sliding portion between the piston and the valve body of the connecting portion. .

Therefore, according to the first aspect of the present invention, the piston is slidably connected to the connecting portion of the valve body in the radial direction, and the sliding portion between the piston and the valve body of the connecting portion is a sealing member. Is provided, the piston and the valve element are combined so as to be relatively displaceable in the radial direction with respect to each other, and the piston can be displaced to a position coinciding with the axis of the cylinder inner wall, and the valve element coincides with the axis of the valve seat. Can be displaced. Therefore, when the piston and the valve element are assembled to the valve body, the position of each axis can be adjusted by itself so as to reduce the sliding resistance.

According to a second aspect of the present invention, there is provided the pressure control valve according to the first aspect, wherein the pressure control valve is engaged with a coupling portion of the valve body so as to transmit a displacement of the piston in an axial direction. An engagement portion is provided on the piston. Therefore, according to the second aspect of the present invention, since the piston is provided with the engagement portion that engages with the coupling portion of the valve body to transmit the displacement of the piston in the axial direction, the piston and the valve body have a radius. The valve body can be driven in the valve opening direction or the valve closing direction by an axial force corresponding to a change in the operating pressure acting on the piston.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a pressure control device to which an embodiment of the present invention is applied. FIG. 2 is an enlarged longitudinal sectional view showing the inside of the pressure control valve. As shown in FIG. 1, the pressure control device includes a pressure control valve 1 and a pressure control unit 52 described later. First, the configuration of the pressure control valve 1 will be described.

The pressure control valve 1 is provided in a gas supply line, and is downstream by operating a valve body 5 in a valve opening and valve closing direction with respect to a valve seat 4 provided in a flow path 3 in a valve body 2. Side secondary pressure is controlled to a predetermined target pressure. As shown in FIG. 2, the valve element 5 is integrally connected to the piston 12 driven by the operating pressure adjusted by the pressure control unit 52, and slides in a valve opening or valve closing direction according to a change in the operating pressure. So that it is attached.

The valve body 2 has an upstream flange 2a to which an upstream pipe 6 is connected on the left side, and a downstream pipe 7 below it.
Is connected to the downstream flange 2b. At the center of the upstream flange 2a, an inflow port 2c communicating with one end of the flow path 3
And an outlet 2d communicating with the other end of the flow path 3 is opened at the center of the downstream flange 2b. The flow path 3 is a valve body 2
Is defined by a partition 8 formed so as to traverse the inside of the inside of the container, into an upstream channel 3a communicating with the inflow port 2c and a downstream channel 3b communicating with the outflow port 2d.

Here, the pressure in the upstream flow path 3a is expressed as a primary pressure P ₁ , and the pressure in the downstream flow path 3b is expressed as a secondary pressure P ₂ . In the present embodiment, for example, the primary pressure P ₁ is set to a considerably high pressure of 70 kg / cm ² . The valve seat 4 is formed in a ring shape, is fitted in a central hole 9 formed in the partition 8, and is fixed to the partition 8 by tightening a bolt 10. When the valve element 5 is lowered by the valve closing operation, the seat portion 15 of the valve element 5 comes into contact with the upper surface of the valve seat 4.

A cage guide 11 is provided below the valve seat 4. The cage guide 11 is formed in a cylindrical shape, and a plurality of long holes 11a penetrating the inner circumference and the outer circumference are formed in the cylindrical portion. A perforated plate 35 formed in a cylindrical shape is attached to the outer periphery of the cage guide 11. Then, the perforated plate 35 is fixed to the upper end flange portion of the cage guide 11 by a bolt 35a.

Since a plurality of long holes 11a are provided at regular intervals around the entire circumference of the cage guide 11, the cage guide 11 also functions as a throttle. When the valve element 5 opens, the flow of fluid is reduced. Reduce the throttle flow rate. Therefore, the primary pressure P ₁ is be set to a high pressure, it has been decelerated flow rate through the valve seat 4 easier to pressure control at small flow rate region. Valve 5
Is integrally assembled with a piston 12 which is slidably provided in a vertical direction above the valve seat 4 at an upper part, and a cage 1 for guiding an opening and closing operation of the valve body 5 is provided at a lower part of the valve body 5.
3 are integrally provided by bolts 14.

The valve element 5 has a seat portion 15 which comes into contact with the valve seat 4 during the valve closing operation and is separated from the valve seat 4 by the valve opening operation. The cage 13 attached below the valve body 5 includes:
The valve guide 5 slides on the inner periphery of the cage guide 11 to guide the sliding operation. In addition, a plurality of openings 13a through which a fluid passes are formed in the peripheral surface of the cage 13. The opening 13a is formed in a trapezoidal shape, and the opening area increases in accordance with the moving amount of the valve opening operation of the valve body 5. That is, when the valve element 5 starts the valve-opening operation, the opening area is small, the flow rate passing through the valve seat 4 is reduced, and as the valve opening degree of the valve element 5 increases, the valve element 5 is positioned higher than the valve seat 4. The opening area of the opening 13a increases, and the flow rate increases.

Therefore, the flow rate does not increase rapidly when the valve element 5 starts the valve opening operation, but gradually increases as the valve element 5 opens. It is easier to do. The fluid (gas in this embodiment) that has passed through the valve seat 4 from the upstream flow path 3a passes through the hole of the perforated plate 35, flows out to the downstream flow path 3b, and passes through the hole of the perforated plate 35 in the process. It is rectified.

Next, the structure of the valve body 5 and the piston 12 will be described. FIG. 3 is an enlarged longitudinal sectional view showing a coupling portion between the valve element 5 and the piston 12. As shown in FIG. 3, the piston 12 is formed in an annular shape, and has an L-shaped cross section. Further, the piston 12 has a vertical portion 12a extending upward and sliding on the inner wall 41b of the cylinder 41.
And a horizontal portion 12b extending in the horizontal direction. Above the vertical portion 12a, there is provided a concave portion 12c to which a pressing member (engaging portion) 27 for pressing a flange portion (joining portion) 25 of the valve body 5 is attached.

On the outer periphery of the vertical portion 12a, there are provided grooves 12d and 12e in which a seal member 28 for sealing between the vertical portion 12a and the inner wall 41b of the cylinder 41 is mounted. In addition, a groove 12f is provided on the upper surface of the horizontal portion 12b, where a seal member 29 for sealing between the lower surface of the flange 25 of the valve body 5 and the lower surface thereof is mounted. The holding member 27 is formed in an annular shape, and has a bolt insertion hole 27a through which the bolt 26 is inserted, and a groove 2 on the lower surface side.
At 7b, a seal member 30 for sealing between the upper surface of the flange 25 is mounted.

Therefore, the piston 12 is connected to the flange 2 of the valve body 5.
5 is slidably connected to the valve body 5 in the radial direction, and a seal member 29 is provided at a sliding portion between the piston 12 and the valve body 5 of the flange portion 25, and a leak between the upstream side flow path 3 a and the pressure chamber 40 is provided. Has been prevented. Further, the holding member 27 is a flange 2 of the valve body 5.
5 is fixed to the upper part of the piston 12 so as to transmit the displacement of the piston 12 in the axial direction.

When the holding member 27 is attached to the concave portion 12c of the vertical portion 12a, the engaging groove 3 having a U-shaped cross section is formed.
1 is formed. The engagement groove 31 is provided on the flange 25 of the valve body 5.
Having a groove width Hb slightly larger than the thickness Ha
<Hb). The outer diameter La of the flange 25 of the valve element 5 is smaller than the inner diameter Lb of the vertical part 12a (La <Lb). Therefore, the flange portion 25 of the valve element 5 is fitted in the engagement groove 31 so as to be movable in the radial direction and is restricted from moving in the axial direction (vertical direction). Therefore, the piston 12 and the valve element 5 are combined so as to be movable in the radial direction.

That is, for example, when the piston 12 is worn out and replaced, the piston 12 and the valve element 5 are combined so as to be relatively displaceable in the radial direction, and the piston 12 is located at a position coincident with the axis of the cylinder inner wall 41b. The valve body 5 can be displaced to a position coincident with the axis of the valve seat 4 while being displaced.
Therefore, by assembling the piston 12 and the valve body 5 to the valve body 2, it is possible to adjust the positions of the respective axes so that the sliding resistance is reduced.

Further, since the alignment between the piston 12 and the cylinder 41 and the alignment between the valve body 5 and the valve seat 4 are facilitated, the sliding resistance of the piston 12 is reduced to reduce the wear of the piston 12. Can be. Thereby, the replacement time of the piston 12 can be extended, and the number of times of replacement of the piston 12 can be reduced. Since the minute gap 32 is formed between the upper and lower surfaces of the flange 25 and the inner wall of the engagement groove 31, the piston 12 and the valve element 5 can be relatively displaced. On the other hand, when the piston 12 slides,
The seal member 29 or 30 is compressed by the space 32. Therefore, although the sliding operation delay occurs between the piston 12 and the valve element 5, the operation delay between the piston 12 and the valve element 5 due to the change in the operating pressure can be ignored because the gap 32 is extremely small. It is about.

The material of the piston 12 is, for example, forging brass (C3712 or C3771) or phosphor bronze casting (PBC2), and is formed of a relatively soft metal material having a surface hardness of about Hv100. In contrast, the material of the valve body 5 is made of carbon steel forgings (SF440), surface hardness by Tufftride surface treatment (salt溶窒reduction) of the metallic material having high hardness than H _V 620-640 degrees and the piston 12 Is formed. Therefore, the valve element 5 is stronger and more durable than the piston 12.

The cylinder 41 is formed of a carbon steel forged product (SF440), which is the same material as the valve body 5. Further, the surface of the cylinder 41, since Electroless nickel plated (nickel-phosphorus alloy plating) is applied, the surface hardness has a considerably high hardness of about H _V 800 to 1000. Therefore, since the piston 12 is formed of a material having a surface hardness lower than that of the cylinder 41, even if the piston 12 slides inside the cylinder 41, the inner wall of the cylinder 41 is not damaged.

As described above, the piston 12 is connected to the cylinder 41
Since the inner wall 41b of the cylinder 41 is not damaged, the piston 1
When the seal member 28 mounted in the second grooves 12d and 12e slides on the inner wall 41b of the cylinder 41, the frictional resistance is prevented from increasing, and the sealing performance of the seal member 28 is prevented from being reduced.

Therefore, the valve element 5 operates smoothly due to the pressure difference between the operating pressure P _L (also referred to as the jacket pressure) and the primary pressure P ₁ , so that pressure control can be stably performed. Here, the description returns to FIG. Also, piston 1
2, a position detection rod 36 extending in the vertical direction
Are fixed by bolts 37. Position detection rod 3
In 6, the upper end 36 a protrudes above the lid 38, and the amount of movement of the valve element 5, that is, the valve opening, can be determined from the sliding height position of the upper end 36 a.

The lid 38 for closing the upper opening 2e of the valve body 2
It is fixed to the valve body 2 by bolts 39. Valve body 5 and lid 3
A pressure chamber 40 is formed between the pressure chamber 8 and the pressure chamber 8, and a pressure introducing hole 38 a for introducing pressure into the pressure chamber 40 is formed in the outer periphery of the lid 38. The cylinder 41 has a flange portion 41a that projects radially from the outer periphery and fits into the upper opening 2e of the valve body 2 to abut on the step portion 2f, and a cylinder inner wall 41b formed on the inner periphery and on which the outer periphery of the piston 12 slides. Having. The cylinder 41 has a flange 41a formed with a hole 41d through which a bolt 42 is inserted. The bolt 42 is screwed into a screw hole of the step 2f and fixed to the valve body 2. An O-ring 41 c for sealing between the valve body 2 and the lid 38 is provided in a groove on the outer periphery of the cylinder 41.

Reference numeral 44 denotes a piston pressing coil spring 45 for pressing the piston 12 fixed to the valve body against the valve seat 4,
Reference numeral 46 denotes a spring holder. Reference numeral 47 denotes a spring receiver which is inserted into the recess 44a of the spring holder and abuts against the upper ends of the coil springs 45 and 46. Further, in a concave portion 5 a provided on the lower surface of the valve body 5, a spring receiver 48 abutting on the lower end portions of the coil springs 45 and 46 is rotatably supported by a bearing 49.

A bearing 50 for bearing the position detecting rod 16 is fitted on the inner periphery of the spring retainer 44. 51
Is a valve opening indicating member, which is screwed to the upper surface of the lid 38 and presses the upper flange of the spring retainer 44 against the upper surface of the lid 38. The valve opening display member 51 has a scale 51 for displaying the valve opening.
a and a window 51b for viewing the scale 51a.
The above-described upper end 36a of the position detection rod 36 can be visually recognized from the window 51b of the valve opening display member 51. Therefore, by reading the scale 51a corresponding to the sliding position of the upper end 36a, the valve opening of the valve element 5 can be determined.

Reference numeral 52 denotes a pressure control unit, and the primary pressure supply line 5
And 3,54, the bleed conduit 55 to release the bleed pressure to the downstream side, a pilot valve 56, a hydraulic pressure introduction pipe 57 for introducing the working pressure P _L to the pressure chamber 40, the detection of the downstream pilot valve 56 A detection line 58 for supplying pressure (secondary pressure P ₂ ). Also, the primary pressure supply line 53
Has one end connected to the primary connection port 6 a of the upstream pipe 6 and the other end connected to a branch point 59 of the primary pressure supply pipes 53 and 54. And in the primary pressure supply line 53,
A throttle 60 for limiting the flow rate of the primary pressure P ₁ from the upstream pipe 6 is provided.

Further, one end of the working pressure introducing line 57 is connected to a branch point 59 between the primary pressure supplying line 53 and the primary pressure supplying line 54, and the other end is connected to the pressure introducing hole 38 a of the lid 38. It is connected. Therefore, the pressure chamber 40 is provided with the throttle 6
An operating pressure P _L whose flow rate is limited by 0 is supplied.
One end of the primary pressure supply line 54 is the primary pressure supply line 53.
And a branch point 59 with the working pressure introduction pipe 54,
The other end is connected to the nozzle 56f of the pilot valve 56.

The pilot valve 56 includes a pair of diaphragms 5.
6a, 56b, upper room 56c, middle room 56d, lower room 56
e. The middle chamber 56d is provided with a nozzle 56f connected to the primary pressure supply pipe 54, and the lower chamber 56e
Is provided with a coil spring 56g for pressing the diaphragm 56b. Incidentally, the coil spring 56g is the magnitude of the spring force is changed by Wath turn the adjustment screw 56h, the pilot set pressure P ₀ is adjusted.

Therefore, by changing the pilot set pressure P ₀ , the secondary pressure P ₂ downstream of the pressure control valve 1 is set to a desired target pressure. In addition, a pair of diaphragms 5
6a and 56b are connected to each other and are displaced in the same direction. The diaphragm 56a narrows the flow rate flowing out of the nozzle 56f due to the pressure increase of the upper chamber 56c, and increases the flow rate flowing out of the nozzle 56f due to the pressure drop of the upper chamber 56c. Let it.

The bleed line 55 has one end connected to the middle chamber 56d of the pilot valve 56 and the other end connected to the downstream line 7 of the downstream line 7.
It is connected to the secondary connection port 7a. Therefore, the middle room 56d
Supplied through the bleed pipe 55 escapes to the downstream pipe 7. The detection pipe 58 has one end connected to the upper chamber 56c of the pilot valve 56 and the other end connected to the downstream pipe 7.
Is connected to the secondary connection port 7b. Therefore, the upper chamber 56c of the pilot valve 56 is a pressure corresponding to a change in the secondary pressure P ₂ on the downstream side.

Accordingly, the pressure of the pressure control valve 1 having the above configuration is
Operating pressure P supplied to the power chamber 40_LIs determined by the aperture 60
The flow rate is restricted, and the flow rate
Via bleed line 55 from pilot valve 56
It is determined by the difference from the flow rate discharged to the downstream pipe 7. Ma
The pressure chamber 40 has a primary pressure P₁Through the aperture 60
Primary pressure P₁Pressure P due to supply of
_LDoes not rise rapidly and the secondary pressure P _TwoTo decline
Pilot valve 56 causes gas to flow out to bleed line 55
Pressure (bleed) increases the primary pressure P₁And working pressure
Force P_LIs the pressure required to open valve body 5
Operating pressure P before the difference_LReduce the time to reduce
Wear. Therefore, the secondary pressure P_TwoKeep the target pressure
The valve opening can be controlled stably.

Here, the pressure control operation of the pressure control device having the above configuration will be described. The upstream-side primary pressure P ₁ is supplied to the upstream-side flow path 3 a upstream of the valve seat 4 and to the primary-pressure supply pipe 53. The primary pressure P ₁ is controlled by a throttle 60 provided in the primary pressure supply line 53.
Can reduce the flow rate. Further, the gas discharged from the throttle 60 is supplied into the pressure chamber 40 through the operating pressure introducing pipe 57 as the operating pressure P _L , and a part of the gas is supplied to the pilot chamber through the primary pressure supplying pipe 54. It is supplied to the nozzle 56f of the valve 56. Therefore, the piston 12 of the valve body 5
, A primary pressure P ₁ of the upstream pipeline 3a acts on
The operating pressure P _L of the pressure chamber 40 acts on the upper part of the piston 12.

Therefore, when the pressure difference between the operating pressure P _L of the pressure chamber 40 and the primary pressure P ₁ has not reached the pressure difference at which the valve 5 can be opened, the valve 5 is actuated by the operating pressure P _L and the spring. 45,4
The seat portion 15 is seated on the valve seat 4 by being pressed downward by the pressing force of No. 6. That is, the valve element 5 is in the valve closed state, and shuts off the flow path 3. Here, the gas consumption in the downstream side increases, the secondary pressure P ₂ becomes lower than the target pressure.

As described above, when the secondary pressure P ₂ becomes lower than the target pressure, the pressure in the upper chamber 56c of the pilot valve 56 decreases, so that the diaphragms 56a and 56b are displaced upward. As a result, the diaphragm 56a of the pilot valve 56 is separated from the nozzle 56f. Thus, the gas supplied via the primary pressure supply line 54
Discharged from the nozzle 56f to the middle chamber 56d, the bleed pipe 5
Outflow to 5. Since the throttle 60 is provided in the primary pressure supply pipe 53, the pressure chamber 4 is opened by opening the valve of the nozzle 56f.
The zero gas passes through the working pressure supply line 57 and the primary pressure supply line 54 and flows out to the middle chamber 56d of the pilot valve 56. Further, the gas in the middle chamber 56d is
And flows out to the downstream side pipeline 7 through.

Therefore, the gas in the working pressure introduction pipe 57 and the gas in the pressure chamber 40 flows out to the bleed pipe 55 and the working pressure P
_L decreases. FIG. 4 is a longitudinal sectional view showing a state in which the valve element 5 performs the valve opening operation. As shown in FIG. 4, the resultant force of the operating pressure P _L of the pressure chamber 40 and the pressing force of the springs 45 and 46 becomes smaller than the pressing force of the upstream side flow path 3a due to the primary pressure P ₁ , and this pressure difference The piston 12 is moved by the piston guide 4
The seat portion 15 of the valve element 5 is separated from the valve seat 4 by sliding upward on the first guide surface 41b.

As described above, the flow rate of the operating pressure P _L is restricted by the throttle 60 and is supplied to the pressure chamber 40, so that the amount of bleed flowing from the nozzle 56 f to the bleed conduit 55 can be reduced. Therefore, the downstream pipeline 7 2
Diaphragm 56a following the pressure P ₂ decreases from the target pressure
There when spaced from the nozzle 56f is in the valve open state, by further secondary pressure P ₂ is the diaphragm 56a be reduced is displaced in the detaching direction from the nozzle 56f, the valve body 5 increases the bleeding amount It can be driven in the valve opening direction.

[0047] Thus, the pressure control valve 1 may be the pilot valve 56 in accordance with a variation in the secondary pressure P ₂ is opened and closed to adjust the bleed amount in proportion to the displacement of the diaphragm 56a of the pilot valve 56 . Therefore, is operating so that the pressure control valve 1 is always secondary pressure P ₂ becomes the target pressure, the valve element 5 is moved up and down in response to a pressure difference between the operating pressure P _L and the primary pressure P ₁ by adjusting the spaced position of the seat portion 15 and the valve seat 4 to control the secondary pressure P ₂ to the target pressure.

Further, since the trapezoidal opening 13a is formed in the cage 13 as described above, even if the valve element 5 is separated from the valve seat 4, the opening area does not increase rapidly, and The flow rate to the water will gradually increase. Therefore, the valve element 5 is displaced in the valve opening direction, and a flow rate corresponding to the total opening area of the opening 13a that has escaped from the valve seat 4 is supplied to the downstream flow path 3b. Control becomes stable.

Next, the operation of the pressure control valve 1 when the secondary pressure P _{2 in} the downstream pipe 7 increases will be described.
When the gas usage on the downstream side decreases, the secondary pressure P ₂ rises above the set pressure P ₀ , and the pressure is supplied to the upper chamber 56 c of the pilot valve 56 via the detection pipe 58. Then, the diaphragm 56a of the pilot valve 56 moves downward due to a rise in the pressure of the upper chamber 56c, and the amount of outflow from the nozzle 56f is reduced.

When the amount of gas used on the downstream side decreases and the secondary pressure P ₂ of the downstream pipe line 7 rises to a pressure higher than the target pressure, the diaphragm 56a of the pilot valve 56 is displaced downward and the nozzle 56f is closed. As a result, the amount of bleed flowing from the pilot valve 56 to the bleed line 55 becomes zero. As a result, the pressure supplied from the primary pressure supply line 53 is entirely reduced to the pressure chamber 40 via the working pressure introduction line 57. Supplied to

Therefore, the operating pressure of the pressure chamber 40 increases.
Therefore, the piston 12 is positioned on the guide surface 4 of the piston guide 41.
1b is driven downward in the valve closing direction by sliding downward,
Port 15 is displaced in the direction approaching the valve seat 4 and the downstream pipe
7 to reduce secondary flow P _TwoTo the target pressure.
You. In each of the above embodiments, the gas pressure is controlled.
As described above, the pressure of gas or liquid other than gas
May be controlled.

In the above-described embodiment, the pressing member 27 is mounted on the upper side of the piston 12. However, the present invention is not limited to this, and it is a matter of course that the pressing member 27 may be mounted from below the piston 12. Further, in the above embodiment, the sealing members 30 and 29 are provided on the upper and lower surfaces of the flange 25.
Although the seal between the valve body 5 and the piston 12 which contacts the seal member is described, the present invention is not limited to this, and a seal member may be attached to the outer periphery of the flange 25.

[0053]

As described above, according to the first aspect of the present invention, the piston is slidably connected to the connecting portion of the valve body in the radial direction, and the sliding portion between the piston and the valve body of the connecting portion. Is provided with a seal member, so that the piston and the valve element are combined so as to be relatively displaceable in the radial direction with each other, the piston can be displaced to a position coinciding with the axis of the cylinder inner wall, and the valve element is disposed on the valve seat. It can be displaced to a position coinciding with the axis.
Therefore, when the piston and the valve element are assembled to the valve body, the position of each axis can be adjusted by itself so as to reduce the sliding resistance. Further, since the alignment between the piston and the cylinder and the alignment between the valve body and the valve seat are facilitated, the sliding resistance of the piston can be reduced, and the wear of the piston can be reduced. Thereby, the replacement time of the piston can be extended, and the number of times of replacement of the piston can be reduced.

According to the second aspect of the present invention, the piston is provided with the engaging portion for engaging the coupling portion of the valve body so as to transmit the displacement of the piston in the axial direction. Are combined so as to be relatively displaceable in the radial direction, and the valve body can be driven in the valve opening direction or the valve closing direction by an axial force corresponding to a change in the operating pressure acting on the piston.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a pressure control device to which an embodiment of a pressure control valve according to the present invention is applied.

FIG. 2 is an enlarged longitudinal sectional view showing the inside of a pressure control valve.

FIG. 3 is an enlarged longitudinal sectional view showing a coupling portion between a piston and a valve body.

FIG. 4 is a longitudinal sectional view showing a state in which a valve element performs a valve opening operation.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 pressure control valve 2 valve body 4 valve seat 5 valve body 12 piston 15 seat portion 25 flange portion 27 pressing member 31 engagement groove 40 pressure chamber 41 cylinder 52 pressure control unit 53, 54 primary pressure introduction pipeline 55 bleed pipeline 56 Pilot valve 57 Operating pressure introduction line 60 Throttle

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuo Ozawa 1-6-3 Fujimi, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Tokiko Corporation

Claims (2)

[Claims] 1. A valve body provided between an upstream pipe and a downstream pipe to which a fluid is supplied, slidably fitted to a cylinder inner wall formed in the valve body, An annular piston that moves in a valve closing direction or a valve opening direction due to a pressure difference between an operating pressure introduced into the cylinder and a primary pressure upstream of the valve body; one end is integrally connected to the piston; It becomes a joint,
A valve body having the other end displaced in a direction close to or away from a valve seat in the valve body to change a valve opening degree; a pressure control valve comprising: A pressure control valve, which is slidably connected in a radial direction to the connecting portion, and a seal member is provided at a sliding portion of the connecting portion between the piston and the valve body. 2. The pressure control valve according to claim 1, wherein an engagement portion is provided on the piston so as to transmit an axial displacement of the piston to a connection portion of the valve body. A pressure control valve, characterized in that: