JP2991231B2 - Pressure control valve - Google Patents

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 easily perform a check operation 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. And
Pressure control valves include an "unloading type" in which the primary pressure acts on the valve element in the valve closing direction and a "loading type" in which the primary pressure acts on the valve element in the valve opening direction.

[0003] In the unloading type pressure control valve, the operating pressure supplied to the valve drive unit and the pressure acting on the valve body are increased.
The valve is driven in the opening or closing direction based on the pressure difference from the next pressure to vary the valve opening, and pressure control is performed so that the secondary pressure becomes a predetermined target pressure. As the valve drive unit that drives the valve element by the pressure difference between the operating pressure and the primary pressure acting on the valve element as described above, a diaphragm method using a flexible diaphragm such as rubber, There is a piston type in which an integrally provided piston is slidably fitted in a pressure chamber 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 system with excellent pressure resistance is used as the 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 valve closing 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 decreases to a pressure close to the secondary pressure, the valve element 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.

As described above, 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 becomes the target pressure. Is controlled.

[0007]

In the conventional pressure control valve, an O-ring as a seal member is provided around the outer periphery of the piston.
The O-ring seals the space between the outer periphery of the piston and the pressure chamber of the valve body. However,
If this one O-ring is broken, there is a problem that the primary pressure leaks from the gap between the piston and the pressure chamber to the upper part of the piston, and the operating pressure fluctuates.

In order to improve the reliability of the seal between the piston and the pressure chamber, it has been considered to attach two O-rings to the outer periphery of the piston. However,
When the reliability is improved by increasing the number of O-rings, the primary pressure gradually enters between the two O-rings, and the pressure remains between the O-rings.

For this reason, when the primary pressure and the secondary pressure are reduced to the atmospheric pressure when the pressure control valve is inspected, if the piston is pulled upward from the pressure chamber, the pressure remains between the two O-rings. When the O-ring located above is released from the sliding portion of the pressure chamber, the residual pressure gushes at once, generating a loud popping sound, and the residual pressure between the two O-rings causes an upper O-ring. Could pop out.

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

[0011]

In order to solve the above problems, the present invention has the following features. The present invention relates to a valve body provided between an upstream pipe and a downstream pipe to which a fluid is supplied, and a valve which is displaced in a direction close to or away from a valve seat in the valve body. A valve body for changing the opening degree, slidably fitted in a pressure chamber in the valve body, and a pressure difference between an operating pressure introduced into the pressure chamber and a primary pressure upstream of the valve body. A piston for driving a valve body in a valve closing direction or a valve opening direction, wherein a plurality of sealing members for sealing between an outer periphery of the piston and a pressure chamber in the valve body are provided on an outer periphery of the piston. One end is opened on the upper surface of the piston, and the other end is opened on the outer periphery of the piston between the plurality of seal members and communicates with the space between the pressure chamber and the plurality of seal members. The communication hole is provided in the piston, and is opened on an upper surface of the piston. It is characterized in that the closing member for closing the end mounted displaceably in the open or closed position.

Therefore, according to the present invention, the piston is provided with a communication hole communicating the pressure chamber and the space between the plurality of seal members, and the closing member is opened or closed at one end of the communication hole opened on the upper surface of the piston. Because it is displaceably attached to the position,
When the piston is removed from the valve body at the time of inspection or the like, the closing member is displaced to the open position, and the pressure accumulated in the space between the plurality of seal members can be released to the outside through the communication hole. Jumping out due to the pressure between the plurality of seal members is prevented.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a pressure control valve according to 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 the first embodiment of the present invention is applied.
FIG. 3 is an enlarged longitudinal sectional view showing the inside of the pressure control valve.

The pressure control device comprises a pressure control valve 1 and a pressure control section 52 to be described later. Pressure control valve 1
Is provided in a gas supply line, and operates a valve element 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 so that a secondary pressure on the downstream side is predetermined. Is controlled to the target pressure.

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.
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 divided into an upstream flow path 3a communicating with the inflow port 2c and a downstream flow path 3b communicating with the outflow port 2d by a partition wall 8 formed so as to cross the inside of the valve body 2. It is defined. Here, the pressure of the upstream side flow passage 3a is primary pressure P _1, the pressure of the downstream side flow path 3b represents the secondary pressure P _2. In this embodiment, for example, the primary pressure P ₁ = 70 kg / cm ²
And is set to quite high pressure.

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 piston 12
Of the valve seat 4 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. Further, the perforated plate 35 of the cage guide 11 is fixed to the upper end flange by a bolt 35a.

The cage guide 11 has a plurality of long holes 1 all around.
Since 1a is provided at regular intervals, it also functions as a throttle, and when the valve element 5 opens, the flow of the fluid is throttled to reduce the flow velocity. 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.

The valve element 5 integrally includes a piston 12 provided slidably in the vertical direction above the valve seat 4 and a cage 13 provided integrally below the piston 12 with bolts 14. Be combined. 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 piston 12 fits on the inner periphery of the cage guide 11 described above and guides the sliding operation of the piston 12.

A plurality of openings 13a are formed in the peripheral surface of the cage 13 to allow a fluid to pass therethrough. The opening 13a is formed in a trapezoidal shape, and the opening area increases according to the amount of movement of the valve element 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. Opening 13
The opening area of “a” 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. FIG. 3 is a longitudinal sectional view showing an outer peripheral portion of the piston 12 in an enlarged manner.

The outer periphery of the piston 12 is provided with two O-ring grooves 16 and 17. The O-ring grooves 16 and 17 are separated by a predetermined distance in the sliding direction (vertical direction). O-rings 18 and 19 as seal members are mounted inside the O-ring grooves 16 and 17. The O-rings 18 and 19 are mounted at a predetermined interval in the sliding direction (vertical direction), and a closed space 20 is formed between the O-rings 18 and 19 in an annular shape. .

Low friction members 21 and 22 having a U-shaped cross section are fitted on the outer peripheral sides of the O-rings 18 and 19, respectively. The low friction members 21 and 22 are formed in a ring shape by, for example, tetrafluoroethylene resin or the like, and are in sliding contact with a guide surface 41 b of a piston guide 41 mounted in the valve body 2. Therefore, the sliding resistance when the pressure is controlled by the piston 12 sliding in the valve opening direction or the valve closing direction is reduced. Therefore, the valve element 5 can smoothly operate due to the pressure difference between the operating pressure P _L (also referred to as jacket pressure) and the primary pressure P ₁ to stably perform pressure control.

Therefore, the piston 12 and the piston guide 4
1, the O-rings 18, 19 and the low friction members 21,
22 forms a double seal structure. Further, even if the lower O-ring 19 and the low friction member 22 are damaged, the space between the piston 12 and the piston guide 41 can be sealed by the upper O-ring 18 and the low friction member 22.
Next the pressure P ₁ passes through the space between the piston 12 and the piston guide 41 is prevented from flowing into the piston 12 top, is prevented from varying the working pressure P _L in the pressure control operation becomes unstable .

The piston 12 is provided with a depressurizing mechanism 24 for releasing the pressure remaining in the space 20 formed between the O-rings 18 and 19 to the outside as described later. The depressurizing mechanism 24 has a first passage 25 having one end communicating with the space 20 between the O-rings 18 and 19 and the other end extending toward the center of the piston 12, and an upper end formed on the upper surface of the piston 12. A second passage 26 having an opening and a lower end extending in a hanging direction and communicating with the first passage 25;
Into the female thread of the upper opening 26a of the second passage 26.
(A closing member) 27 that closes the plug 27, and an O-ring 28 that contacts the lower end of the plug 27 and seals between the upper opening 26a and the plug 27.

Normally, the plug 27 is screwed into the position where the O-ring 28 is compressed, and the second passage 23 is closed. The plug 27 has a driver groove 27a at the upper end.
The outer periphery is provided with a male screw 27b and a pressure relief groove 27c extending in the axial direction. In addition, although the upper end of the pressure release groove 27c is open at the upper end of the plug 27,
The lower end is not opened at the lower end of the plug 27 so as not to damage the O-ring 28, and the lower end of the plug 27 is flat.

When the plug 27 is compressing the O-ring 28, the lower end of the plug 27 is sealed by the O-ring 28, so that the space between the pressure relief groove 27c and the second passage 26 is shut off. Space 20, passage 2
Outflow of the gas remaining at 5, 26 is prevented.

When the plug 27 is screwed into the closed position, the plug 27 is in the upper opening 26a of the second passage 26,
Since it does not protrude from the upper surface of the piston 12, the plug 2
7 does not come into contact with other members, and the piston 1
2, or the plug 27 does not move to the open position during pressure control.

FIG. 4 shows an empty space formed on the outer periphery of the piston 12.
Enlarged view for explaining the operation when the pressure in the interval 20 is released
It is. When performing inspection work, make sure that the pressure control valve 1 is
Close the flow side valve and set the primary pressure P ₁, Secondary pressure P_TwoAnd work
Dynamic pressure P_LAfter reducing the pressure to atmospheric pressure, the plug 27 is
Rotate using a tool such as a bar or a coin, and plug
Move the lower end of the plug 27 from the O-ring 28
Separate.

As a result, the pressure relief groove 27b communicates with the second passage 26 through the gap between the female screw and the male screw 27b of the upper opening 26a of the second passage 26, and the space 20,
The gas remaining in the passages 25 and 26 is exhausted above the piston 12 through the gap of the screw and the pressure relief groove 27b. As a result, the pressure in the space 20 formed between the O-rings 18 and 19 is reduced to the atmospheric pressure.

Therefore, when the piston 12 is pulled upward from the valve body 2, the upper O-ring 18 and the low friction member 2
1 jumps out due to the residual pressure in the space 20 or the space 2
It is possible to prevent the residual pressure in 0 from being blown out at once to generate a large plosive sound. Also, the plug 27 is used to release the residual pressure in the space 20 because the external thread 27b is screwed into the female thread of the upper opening 26a of the second passage 26 when releasing the residual pressure in the space 20 to the outside. Is prevented from jumping out. Therefore, the plug 2 is released by the above-described depressurizing operation.
7 is not lost.

Returning to FIGS. 1 and 2, the description will be continued. A cylindrical perforated plate 35 is provided around the cage guide 11. The perforated plate 35 has a large number of holes formed on the outer peripheral surface. Therefore, 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. It is rectified in the process.

A vertically extending position detecting rod 36 is fixed to the center of the piston 12 with a bolt 37. The upper end 36a of the position detecting rod 36 has the lid 3
8, 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 36a.

The lid 38 for closing the upper opening 2e of the valve body 2 is
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. In addition, since the valve element 5 operates in the valve opening or valve closing direction according to the pressure value supplied to the pressure chamber 40,
The pressure chamber 40 and the piston 12 constitute a valve drive unit.

Reference numeral 41 denotes a piston guide which protrudes radially from the outer periphery and fits into the upper opening 2e of the valve body 2 to form a step 2f.
A flange 41a contacting the piston 12 and the piston 12
And a guide surface 41b on which the outer circumference slides. The piston guide 41 has a flange 41a formed with a hole 41d through which a bolt 42 is inserted. The bolt 37 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 piston guide 41.

Reference numeral 44 denotes a spring press of the coil springs 45 and 46 for pressing the piston 12 against the valve seat 4. Reference numeral 47 denotes a spring which is inserted into the concave portion 44a of the spring press and abuts on the upper ends of the coil springs 45 and 46. It is receiving. Also, a concave portion 12a provided on the upper surface of the piston 12
, A spring receiver 48 abutting on the lower ends 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 section, primary pressure supply pipes (communication pipes) 53 and 54, a bleed pipe 55 for releasing bleed pressure to the downstream side, a pilot valve 56, and an operating pressure in the pressure chamber 40. Working pressure introducing line 57 for introducing P _L
And the detected pressure on the downstream side (secondary pressure P
₂ ) and a detection line 58 for supplying the same.

The primary pressure supply pipe 53 has one end connected to the primary connection port 6a of the upstream pipe 6 and the other end connected to a branch point 59 of the primary pressure supply pipes 53 and 54. Have been. The upstream pressure line 6 is connected to the primary pressure supply line 53.
An aperture 60 for limiting the flow rate of the primary pressure P ₁ from, are disposed.

Further, one end of the working pressure introduction pipe 57 is connected to a branch point 59 between the primary pressure supply pipe 53 and the primary pressure supply pipe 54, and the other end is connected to the pressure introduction 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 a branch point 59 between the primary pressure supply line 53 and the working pressure introduction line 54.
And the other end is connected to the nozzle 56f of the pilot valve 56. The pilot valve 56 is defined by a pair of diaphragms 56a and 56b as an upper chamber 56c, a middle chamber 56d, and a lower chamber 56e. The middle chamber 56d is provided with a nozzle 56f connected to the primary pressure supply pipe 54,
6e is a coil spring 56 for pressing the diaphragm 56b.
g intervenes. In addition, the coil spring 56g is an adjusting screw 56h.
By turning, the magnitude of the spring force is changed, and the pilot set pressure P ₀ is adjusted.

Therefore, the secondary pressure P ₂ downstream of the pressure control valve 1 is set to a desired target pressure by changing the pilot set pressure P ₀ . 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
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 working pressure P _L supplied to the pressure chamber 40 of the pressure control valve 1 having the above-described structure is limited in flow rate by the throttle 60, and is controlled by the flow rate discharged from the throttle 60 and the pilot valve 56. It is determined by the difference from the flow rate discharged to the downstream pipe 7 through the bleed pipe 55.

The pressure chamber 40 has a primary pressure P₁Is squeezed
The primary pressure P₁To supply
Working pressure P_LPressure does not rise rapidly and the secondary pressure
Force P _TwoOf the bleed line 5
When the gas outflow (bleed amount) to 5 increases, the primary pressure
Force P₁And working pressure P_LPressure difference causes the valve element 5 to open.
Operating pressure P until the pressure difference required for_LLower
Time can be reduced. Therefore, the secondary pressure P_TwoIs the goal
The valve opening can be controlled stably so as to maintain the pressure.

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
The working pressure P _L is supplied into the pressure chamber 40 via the working pressure introducing pipe 57, and a part of the working pressure is supplied to the nozzle 56 f of the pilot valve 56 via the primary pressure supplying pipe 54. Therefore, the lower portion of the piston 12 of the valve body 5, the primary pressure P ₁ is exerted on the upstream side conduit 3a, the upper portion of the piston 12 operating pressure P _L of the pressure chamber 40 acts.

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 element 5 can be opened, the valve element 5 is actuated by the operating pressure P _L and the spring pressure. 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, when the gas usage on the downstream side increases, the secondary pressure P ₂ falls below the target pressure. As described above, when the secondary pressure P ₂ becomes lower than the target pressure,
Since the pressure in the upper chamber 56c of the pilot valve 56 decreases, 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 through the primary pressure supply pipe 54 is discharged from the nozzle 56f to the middle chamber 56d and flows out to the bleed pipe 55. Since the throttle 60 is provided in the primary pressure supply pipe 53, the nozzle 56f
When the valve is opened, the gas in the pressure chamber 40 is released from the working pressure supply line 5.
7 and the primary valve 5
6 flows into the middle room 56d. Further, the gas in the middle chamber 56d flows out to the downstream pipe 7 via the bleed pipe 55.

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. As a result, as shown in FIG.
Resultant force of the pressing force of the hydraulic pressure P _L and springs 45 and 46 0 becomes smaller than the pressing force by the primary pressure P ₁ on the upstream side flow passage 3a, the piston 12 of the piston guide 41 by the pressure difference Guide The seat portion 15 of the valve element 5 is separated from the valve seat 4 by sliding upward on the surface 41b.

As described above, since the flow rate of the operating pressure P _L is restricted by the throttle 38 and supplied to the pressure chamber 40, the amount of bleed flowing from the nozzle 56f 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 in the open state separated from the nozzle 56f, 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.

[0054] 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.

Also, 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 7 rises to a pressure higher than the target pressure, the diaphragm 56a of the pilot valve 56 is displaced downward and the nozzle 56 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.

FIG. 6 is an enlarged view of a main part of the second embodiment of the present invention. Reference numeral 61 denotes a pressure release mechanism for releasing the pressure remaining in the space 20 formed between the O-rings 18 and 19 to the outside. A first passage 25 extending toward the center of the piston 12, a second passage 26 having an upper end opening on the upper surface of the piston 12 and a lower end extending in a hanging direction and communicating with the first passage 25, A plug (blocking member) 62 that is screwed into the female screw of the upper opening 26 a of the second passage 26 and closes the second passage 26.

The plug 62 has a driver groove 62a at the upper end, and a male screw 62b screwed to the female screw of the upper opening 26a on the outer periphery. The plug 62 is provided with a through hole 62c at an eccentric position away from the axis. The through hole 62c passes through the upper end and the lower end of the plug 62, but is located at an eccentric position deviated from the second passage 26, so that the lower end of the plug 62 is located at the step 2 of the upper opening 26a.
When it is screwed into the position where it comes into contact with 6b, the lower end opening of the through hole 62c is closed by the step 26b of the upper opening 26a.

Therefore, the plug 62 is normally screwed into the upper opening 26a of the second passage 26 until the lower end of the plug 62 contacts the step 26b of the upper opening 26a. Therefore, at the time of pressure control, the second passage 26 is closed by the plug 62, and the outflow of gas remaining in the space 20, the passages 25, 26 is prevented.

When the plug 62 is screwed into the closed position, the plug 62 is in the upper opening 26a of the second passage 26,
Since it does not protrude from the upper surface of the piston 12, the plug 6
The upper end of the piston 2 does not come into contact with other members and the piston 1
2 or the plug 62 does not move to the open position during pressure control.

FIG. 7 shows an empty space formed on the outer circumference of the piston 12.
FIG. 3 is an enlarged view for explaining an operation when the pressure of the interval 20 is released.
is there. When performing inspection work, upstream and downstream of the pressure control valve 1
Side valve is closed and the primary pressure P ₁, Secondary pressure P_TwoAnd operation
Pressure P_LAfter reducing the pressure to atmospheric pressure,
Rotate using a tool or coin, etc.
62 to move the lower end of the plug 62 into the upper opening 26a.
It is separated from the step 26b.

As a result, the through hole 62c of the plug 62 communicates with the second passage 26, and the gas remaining in the space 20, the passages 25 and 26 passes through the through hole 62c and is exhausted above the piston 12. As a result, the pressure in the space 20 formed between the O-rings 18 and 19 is reduced to the atmospheric pressure.

Therefore, when the piston 12 is pulled upward from the valve body 2, the upper O-ring 18 and the low friction member 2
1 jumps out due to the residual pressure in the space 20 or the space 2
It is possible to prevent the residual pressure in 0 from being blown out at once to generate a large plosive sound. Also, when the residual pressure in the space 20 is released to the outside, the male screw 62b is screwed into the female screw of the upper opening 26a of the second passage 26 even when the residual pressure in the space 20 is released to the outside. Is prevented from jumping out. Therefore, the plug 2 is released by the above-described depressurizing operation.
7 is not lost.

As a modification of the above embodiment, the upper opening 2 of the second passage 26 opening on the upper surface of the piston 12
The plug 27 or 62 is screwed into the second passage 26a.
Instead of closing the first passage 25, a first valve 25 may be opened and closed by inserting a spool valve into the second passage 26 and rotating a lever protruding from the upper surface of the piston 12, for example.

Although the above embodiments have been described as controlling the pressure of a gas, the pressure of a gas other than a gas or a liquid may be controlled. In the above embodiment, two O-rings 18, 1
9 has been shown as an example, but the present invention is not limited to this, and the present invention can of course be applied to a configuration in which two or more O-rings are mounted on the outer periphery of the piston 12. It is.

[0068]

As described above, according to the present invention, the piston is provided with a communication hole for communicating the pressure chamber with the space between the plurality of seal members, and the closing member is provided at one end of the communication hole opened on the upper surface of the piston. Is displaceably attached to the open or closed position, the pressure accumulated in the space between the plurality of seal members by displacing the closing member to the open position when removing the piston from the valve body at the time of inspection, etc., through the communication hole. The seal member can escape to the outside, thereby preventing the seal member from jumping out due to the pressure between the plurality of seal members. Further, it is possible to prevent the popping sound from being generated when the seal member pops out.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a pressure control device to which a first 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 main part of the first embodiment.

FIG. 4 is an enlarged view for explaining an operation when the pressure in a space formed on the outer periphery of the piston is released.

FIG. 5 is a longitudinal sectional view for explaining a pressure control operation of the pressure control valve.

FIG. 6 is an enlarged longitudinal sectional view showing a main part of a second embodiment of the present invention.

FIG. 7 is an enlarged view for explaining an operation for releasing pressure in a space formed on the outer periphery of a piston according to the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pressure control valve 2 Valve body 4 Valve seat 5 Valve body 12 Piston 15 Seat part 16, 17 O-ring groove 18, 19 O-ring 20 Space 21, 22, Low friction member 24, 61 Depressurizing mechanism 25 First passage 26 First 2 passage 27, 62 plug 28 O-ring 40 pressure chamber 41 piston guide 52 pressure control unit 53, 54 primary pressure supply line 55 bleed line 56 pilot valve 57 operating pressure introduction line 60 throttle

Continuation of front page (72) Inventor Yasuo Ozawa 1-3-6 Fujimi, Kawasaki-ku, Kawasaki-shi, Kanagawa Tokiko Corporation (56) References JP-A-62-163123 (JP, A) JP-A-49-51468 (JP, A) JP-A-62-13878 (JP, A) JP-A-63-48211 (JP, U) JP-A-60-144111 (JP, U) JP-A-5-12914 (JP, U) ( 58) Field surveyed (Int.Cl. ⁶ , DB name) G05D 16/00-16/20

Claims (1)

(57) [Claims] 1. A valve body provided between an upstream pipe and a downstream pipe to which a fluid is supplied, and a valve which is displaced in a direction close to or away from a valve seat in the valve body. A valve element for changing an opening degree, slidably fitted in a pressure chamber in the valve body, and a pressure difference between an operating pressure introduced into the pressure chamber and a primary pressure upstream of the valve body. A piston that drives the valve body in a valve closing direction or a valve opening direction; and a pressure control valve comprising: a plurality of sealing members that seal between an outer periphery of the piston and a guide portion in the valve body; One end is opened on the upper surface of the piston, and the other end is opened on the outer periphery of the piston between the plurality of seal members, and has a communication hole communicating between the inside of the guide portion and a space between the plurality of seal members. The piston is provided on the piston, and is opened on an upper surface of the piston. A pressure control valve, wherein a closing member for closing one end of a communication hole is movably attached to an open or closed position.