JP2002174360A - Pilot valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To significantly improve the operation and effect of a pilot valve by reexamining the function of the pilot valve that works at a pressure higher than a set pressure or lower than the set pressure, and allowing a passage to conduct at both high and low pressures to the set pressure, according to each case. SOLUTION: This pilot valve comprises a plurality of valve elements set on a sliding rod driven by a diaphragm, and respective passages corresponding thereto. The valve elements are driven in the opposite directions by the movement of the diaphragm, whereby one valve element and the other valve element can be opened and closed, respectively, or both can be opened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pilot valve used for controlling opening and closing of an automatic valve and the like.

[0002]

2. Description of the Related Art Conventionally, a pilot valve has been widely used as a control device for various automatic valves and the like, and a difference occurs between a predetermined fluid pressure and a pressure to be controlled (a secondary side). Then, the pilot valve is opened, and the operation of the connected various automatic valves is started. Regarding the pressure difference, when the pressure of the part to be controlled becomes lower than the set value, it operates when the pressure of the part to be controlled becomes higher than the set value. There are two types of pilot valves of the “pressurized open” type that are operated and used depending on the purpose of use.

The operation of the conventional type will be described with reference to FIG. 14 which is a schematic diagram in which an automatic valve and a pressurized open pilot valve for operating the same are combined. The pilot valve P shown in the upper part of FIG. Set value by rotation of spring S
The operation of the diaphragm D is transmitted to the valve body V by the straight rod K in such a manner that the operation is transmitted to the diaphragm D via a. The valve body V always closes the conduction hole O under the action of the spring Sb. The conduction hole O is opened only when the straight rod K is pressed by the diaphragm D and descends. The fluid can flow into the downstream side L via the communication hole O. The pressure of the spring Sa is applied to the upper surface of the diaphragm D, and the pressure of the fluid on the downstream side L is applied to the lower surface via the passage J.

An automatic valve A to which such a pilot valve P is connected has a primary side B and a secondary side C which are shut off by a valve body X, and a sliding rod E for operating the valve body X moves in the cylinder chamber F. The piston G is connected to a sliding piston G, and the piston G is urged in a space M thereabove under the action of a spring Y so that the valve body X closes the primary side B and the secondary side C. The fluid on the primary side B flows into the cylinder chamber F below the piston G via the communication hole Fa, and is supplied to the space M above the piston G via the opening Z. Thus, the pressure on the primary side B is equally applied to the upper and lower pressure receiving surfaces of the piston G, but the piston G is lowered by the bias of the spring Sa installed in the space M and the valve connected thereto is The interruption between the primary side B and the secondary side C by the body X is ensured. Further, the space M has an outlet Za, and the outlet Z
When the fluid flows out of the piston a, the balance of the fluid pressures applied to the upper and lower pressure receiving surfaces of the piston G is removed, and the pressure in the space M decreases, so that the piston G rises in the cylinder chamber F, The rise causes the valve body X to rise, that is, to open the shutoff between the primary side B and the secondary side C.

When these are used in combination, the downstream side L of the pilot valve P is connected to the secondary side C of the automatic valve A and the upstream side H of the pilot valve P is connected to the discharge port Za of the automatic valve A as shown in the figure. And the primary side B of the automatic valve A is connected to the opening Z of the space M. Although not shown, a pipe on the source side of the fluid to be controlled is connected to the primary side B of the automatic valve A, and a pipe to the destination side is connected to the secondary side C.

The operation of the pilot valve P
Is set in advance by the handle N, and when the pressure on the downstream side L of the pilot valve P (that is, the secondary side C of the automatic valve A) falls below the set value, the diaphragm D
To move the straight rod K downward, whereby the valve body V moves down against the spring Sb to open the conduction hole O. The fluid in the space M of the automatic valve A is thereby discharged.
a, the upstream side H, the conduction hole O, and the downstream side L of the pilot valve P
Further, it flows to the secondary side C of the automatic valve A, and the space M of the automatic valve A
Is reduced, the piston G rises in the cylinder chamber F, the valve body X of the automatic valve A connected to the piston G rises, the fluid on the primary side B flows into the secondary side C, and the secondary side C Increase pressure.

When the pressure on the secondary side C of the automatic valve A reaches the set value, the pressure on the downstream side L of the pilot valve P also reaches the set value, and the diaphragm D returns to the old position by the pressure. At the same time, the valve body V and the straight rod K return under the action of the spring Sb, and the conduction hole O is closed by the valve body V.
By closing the through hole O, the outflow of the fluid in the space M of the automatic valve A is stopped, the fluid on the primary side B of the automatic valve A flows into the space M through the opening Z, and the pressure in the space M is reduced by the cylinder. When the pressure becomes equal to the pressure applied to the lower surface of the piston G in the chamber F, the piston G is pushed down by the urging of the spring Y, and the valve body X connected thereto is moved to the primary side B and the secondary side C. And the supply of fluid to the secondary side C is stopped. The above is an example of the operation of an automatic valve using a pilot valve that has been generally performed conventionally.

FIG. 15 shows an example in which a conventional pressure-opening pilot valve Pa is combined with an automatic valve A similar to that described above, and is opened when the pressure of a portion to be controlled is higher than a set value. When using this type of pilot valve Pa, the downstream side L of the pilot valve Pa is connected to the secondary side C of the automatic valve A.
And the upstream side H of the pilot valve Pa is connected to the discharge port Z of the space M of the automatic valve A. Furthermore, the primary side B of the automatic valve A
Is supplied to the space M of the automatic valve A via the discharge port Za, and presses downward the piston G located in the space M.

The pressure on the primary side B of the automatic valve A is equal to the pilot valve P
When the pressure exceeds a set value, the diaphragm D rises, the valve body V connected thereto is pulled up, and the conduction hole O is opened. Then, the fluid inside the space M of the automatic valve A flows from the outlet Z to the upstream side H of the pilot valve Pa,
Further, from the downstream side L to the secondary side C of the automatic valve A through the communication hole O.
Flows into As a result, the pressure inside the space M of the automatic valve A decreases, and the pressure on the primary side B received by the upper surface of the piston G is smaller than the pressure on the primary side B received by the lower surface of the valve body X of the automatic valve A. The valve body X is pushed up and the primary side B
Is discharged to the secondary side C.

When the pressure on the primary side B falls below the set value due to the above-mentioned discharge, a decrease in the pressure is transmitted from the passage J to the diaphragm D of the pilot valve Pa, whereby the diaphragm D descends and the valve body V also decreases, the communication hole O is closed by the valve body V, the outflow of the fluid in the space M of the automatic valve A is stopped, and the fluid on the primary side B is opened.
a to the space M to increase the internal pressure, and as a result, the piston G descends and the valve body X cuts off the conduction between the primary side B and the secondary side C of the automatic valve A.

[0011]

Both the depressurized open type and the pressurized open type start when the difference between the set value and the pressure of the part to be controlled occurs, and are connected to each other by starting the pilot valve. The operation of the automatic valve or the like is started, and the automatic valve is opened and closed to fill the generated differential pressure, and the pressure of the portion to be controlled is shifted to a desired value. After the pressure of the part to be controlled reaches a desired value, the pilot valve is closed, and the automatic valves and the like connected to the pilot valve also start to close. Since the control is performed by the pressure of the fluid that is being conducted, and also in this case, a differential pressure is used, and it often takes longer than expected to close the valve. For example, in the above-described first conventional example, after the pilot valve P is closed and the fluid outflow from the space M of the automatic valve A is stopped, the space M above the piston G is stopped.
When the pressure becomes equal to the pressure on the primary side B, that is, the pressure in the cylinder chamber F below the piston G, the "close" operation of the valve element X is first started by the difference in the pressure receiving area and the urging of the spring Y. Will be.

Such an operation is performed by setting the automatic valve A to the piston G
It is inevitable that the operation is performed by the differential pressure between the upper and lower pressure receiving surfaces of the piston G shown in FIGS. 14 and 15, but it is necessary to wait for the pressure in the space M to gradually recover. Is not a desirable state. It is desirable that opening and closing of the valve by moving the valve element be performed quickly, and if the operation is slow, it may cause inconvenience such as hunting. Most of the causes are "Pressure opening" and "Decompression opening"
There is a problem in the conventional way of thinking that any pilot valve is a means for giving a trigger to the operation of an automatic valve or the like controlled by the pilot valve. According to FIG. 8 showing the set value, the flow rate, and the pressure to be controlled based on such a concept, the right side of the vertical axis in the figure showing a portion having a higher value than the set value in the “depressurized open” type pilot valve Since only the portion was considered and the flow rate and pressure in the portion on the left side of the vertical axis which existed even when the value was below the set value were ignored, a desirable pilot valve could not be obtained. The present invention seeks a new type of pilot valve that previously utilized only some of its functions, both when the fluid pressure of the part to be controlled is higher than the set value and when the fluid pressure is lower than the set value. The purpose is to clearly recognize the pressure and flow rate that are always present, and to effectively use the flow rate and pressure indicated by a solid line from the lower left to the upper right as shown in FIG. 6 with one pilot valve. In addition, as shown in FIG. 7, a pilot valve is obtained in which a line in which the flow rate increases with an increase in the secondary pressure and a line in which the flow rate decreases decrease from the set value on the same stage according to the change in the secondary pressure. It is also intended.

[0013]

Since it is impossible to control different flow paths of two systems by a single valve element, a plurality of valve elements are accommodated in a single pilot valve, and The operation of the diaphragm determines that the valves are alternately opened and closed, and a flow path corresponding to the plurality of valves is provided to achieve a desired purpose. Physically convert the non-operating state in which the diaphragm keeps a plane according to the set value and the deformed operating state to the operation of two or more valve elements,
By properly arranging the flow path connected to the valve body,
For example, the opening and closing of an automatic valve or the like connected to the pilot valve is quickly performed.

The basic structure is such that valve bodies are attached at a plurality of positions of a sliding rod which is slid by a diaphragm, and valve seats at appropriate positions of a flow path in the pilot valve are respectively made to correspond to the valve bodies. The valve seat is selectively designed to be opened or closed in the inoperative and operative positions of the diaphragm. As a result, the conventional pilot valve (for example, a pressure-reducing open pilot valve) performs an operation of closing the valve seat when the diaphragm is not operating and opening the valve seat when the diaphragm is operating, whereas the pilot valve of the present invention has In addition to its operation, the second valve seat is arranged to be opened in the non-operation state and closed in the operation state, so that the movement of the fluid is completely opposite to the movement of the fluid promoted by the operation of the conventional valve body and the valve seat. Since movement control can be added, effective control of an automatic valve or the like that opens and closes using the differential pressure of the fluid becomes possible.

In addition, the diaphragm can be moved in the positive and negative directions from the non-operating position by setting the non-operating position in an equilibrium state. In the conventional pressure reducing open pilot valve P shown in FIG. 14, the pressure on the downstream side L is applied to the diaphragm D via the passage J, and when the pressure on the downstream side L falls below a set value, the diaphragm D The valve seat is deformed so as to protrude downward (in the positive direction), the deformation is transmitted to the valve body V by the straight rod K, and the valve body V is lowered against the spring Sb to open the valve seat. , The fluid on the upstream side H can be moved to the downstream side L. However, when the pressure on the downstream side L exceeds the set value, the straight rod K and the diaphragm D are fixed to each other even if the diaphragm D is deformed suddenly (in the negative direction) upward in the drawing. Is not done,
And, the valve body V keeps shutting off between the upstream side H and the downstream side L without changing its position.

Considering the state of equilibrium of the diaphragm, the deformation in the positive direction and the deformation in the negative direction,
There are practically three actions that can be taken out by the diaphragm, and by using that,
In the equilibrium state, the two valve elements are both placed in the closed position, and only the first valve element is moved in the positive direction, and only the second valve element is moved in the negative direction. If this is used for control of an automatic valve or the like, all fluid movements are stopped when the pilot valve is in an equilibrium state according to the set value, and the pressure of the part to be controlled such as the automatic valve is set to the set value. When the pressure falls below the predetermined value, only the first valve is operated by utilizing the deformation of the diaphragm in the positive direction to prompt the opening of an automatic valve or the like to supply necessary fluid to a controlled part, and supply of the fluid When the pressure of the part to be controlled returns to the set value, the first valve is closed, and if the supply continues to exceed the set value, use the fact that the diaphragm of the pilot valve is deformed in the negative direction. And only activate the second valve Te, it is possible to perform the operation of supplying the fluid to the automatic valve such as automatic valve or the like is rapidly closed. If necessary, a design that ensures operation at two points, that is, an equilibrium state and a positive or negative direction is also possible.

According to the present invention, by installing a plurality of valve elements on the pilot valve, the pilot valve, which has been mainly used for pressure detection, is provided with a intentional and forcible fluid to the valve device for controlling. Feeding can be performed simultaneously, which allows quick and smooth control of the valve device.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The basic structure of the pilot valve of the present invention shown in FIGS. 1 and 4 will be described. A major difference between the two embodiments is that the first embodiment shown in FIG. 1 performs the deformation of the diaphragm 2 in the equilibrium position, the downward projection deformation (positive direction deformation), and the upward projection deformation ( In contrast, the second embodiment shown in FIG. 4 uses two points, that is, an equilibrium state and a downward projection deformation. In the first embodiment, in order to use the three-point deformation of the diaphragm, at the equilibrium position, both the two valve bodies inside the pilot valve are closed, and the positive valve is used to set the lower valve body to "close". It is possible to perform the operation of opening the upper valve body and keeping the upper valve body closed, and using the negative deformation to open the upper valve body and keep the lower valve body closed. it can. In order to perform this operation, the sliding rod that transmits the deformation of the diaphragm to the valve body is formed coaxially and double, and when the diaphragm is in an equilibrium state, both of the sliding rods “close” the valve body. When the diaphragm is deformed in the positive direction, one of the sliding rods having a double structure is moved in the same direction to open the lower valve body, for example, when the diaphragm is deformed in the positive direction. And if the diaphragm is deformed in the negative direction, the other of the double-structured sliding rods is moved in that direction to move the upper valve body to the "open" position. .

The second embodiment shown in FIG. 4 is of a type in which the upper and lower valve elements are operated by a single sliding rod, and the fluid flow shown in FIG. Even in such a state, in consideration of the situation that is always required in one of the states, the deformation of the diaphragm is used at two points in the positive and negative directions centering on the equilibrium state, and both are used in the equilibrium state The valve is opened and the lower valve is opened when the valve is deformed in the negative direction.The upper valve is closed when the valve is deformed in the positive direction. "Closed" the valve body below "open"
Is performed.

[0020]

First Embodiment The first embodiment will be described with reference to the structural diagrams of FIGS. 1, 2 and 3, and the operation explanatory diagrams of FIGS. 9, 10 and 11. FIG. FIG. 1 is an internal explanatory view in the case where the diaphragm 1 is in an equilibrium state. The diaphragm 1 is arranged so that the rotation of the upper handle 2 in the figure can be set via a spring 3 so that the value of the pressure to be dealt with can be set. This part is the same as the conventional pilot valve. Reference numeral 4 denotes a detection chamber having an opening 5 and is connected to the diaphragm 1. An operation piece 6 fixed to the diaphragm 1 protrudes into the detection chamber 4, and a first valve body 8 is fixed to a lower end of a sliding rod 7 pressed downward in the drawing by the operation piece 6. A spring 9 that gives a tendency to ascend to one valve body 8 is suspended. Reference numeral 10 denotes a valve rod having a second valve element 11 pulled upward by the operation piece 6, and is "closed" when the diaphragm 1 is in an equilibrium state and a positive deformation state, and is "open" when the diaphragm 1 is in a negative deformation state. ”Is urged downward in the figure by the spring 12. Reference numeral 13 denotes a first opening for connecting a pilot valve to an automatic valve or the like to be operated, 14 denotes a second opening connected to the first opening 13 via the first valve body 8, and 15 denotes a second opening. The third opening is connected to the first opening 13 via the second valve body 11.

The type of connecting the pilot valve to the automatic valve to be controlled according to the present embodiment is as shown in FIG. 9, and the opening Z of the automatic valve A, the first opening 13 of the pilot valve, the automatic valve
A primary side B of A and third opening 15 of pilot valve, automatic valve A
And the second opening 14 and the opening 5 of the pilot valve
Concatenate. FIG. 9 shows that the pressure derived from the secondary side C of the automatic valve A is applied to the detection chamber 4 of the pilot valve when the diaphragm 1 of the pilot valve is at the set value. Set pressure of 1 and secondary side C
Are balanced, the diaphragm 1 is in an equilibrium state, the first valve body 8 and the second valve body 11 are both in the "closed" state, and the automatic valve A is located between the automatic valve A and the pilot valve. No fluid flow is seen.

Now, considering the case where the pressure on the secondary side C of the automatic valve A falls below a set value, the decrease in the pressure on the secondary side C also decreases the pressure in the detection chamber 4 to which the pressure is applied. As a result, the diaphragm 1 is thereby deformed into a downwardly projecting state as shown in FIG. 10, and the operation piece 6 pushes down the sliding rod 7, whereby the first valve body 8 is moved to the spring 9. Descending against the first opening 13 and the second opening 14
The intercept between is released. By the lowering of the first valve body 8,
Fluid in the space M above the piston G of the automatic valve A connected thereto is opened from the opening Z to the first opening of the pilot valve so as to allow conduction between the first opening 13 and the second opening 14. Automatic valve which flows into opening 13 and further flows out of second opening 14
Continue to flow to secondary side C of A. As the pressure in the space M decreases, the piston G rises, the valve body X of the automatic valve A is opened, and the primary side B
Flows into the secondary side C in the same manner as described in the description of the conventional example.

When the valve body X of the automatic valve A is opened, a large amount of fluid on the primary side B flows into the secondary side C, and when the pressure on the secondary side C is increased, the pressure on the secondary side C is received. The pressure in the detection chamber 4 of the pilot valve is also increased, and the diaphragm 1
As shown in FIG. This means that the pressure in the detection chamber 4 has exceeded the set value of the diaphragm 1 anyway, but in that case, the quick closing of the valve body X of the automatic valve A is required, and When the diaphragm 1 is deformed as described above, the pressed sliding rod 7 is released and the first valve body 8 is returned by the action of the spring 9, and the first opening 13 and the second opening 14
Is shut off, the outflow of fluid from the space M of the automatic valve A to the outside is instantaneously stopped, and the valve rod 10 engaged with the operation piece 6 by the same deformation of the diaphragm 1
The opening between the third opening 15 and the first opening 13 is released. As a result, the fluid on the primary side B of the automatic valve A connected to the third opening 15 flows out of the first opening via the second valve body 11 and the opening of the automatic valve A from the first opening 13. After flowing into the space M via Z, the piston G is forcibly depressed and the valve body X of the automatic valve A shuts off between the primary side B and the secondary side C, and the supply of fluid to the secondary side C is stopped. I do.

As described above, according to the present embodiment, when the pressure is lower than the set pressure, the same operation as that of the conventional pressure reducing and opening type pilot valve is performed. It is possible to obtain a new pilot valve capable of switching a path and forcibly and quickly closing an automatic valve or the like to be operated.

[0025]

Second Embodiment A second embodiment will be described with reference to FIGS. 4, 5, 12, and 13. The second embodiment is the same as the first embodiment in that it has two upper and lower valve bodies,
The first embodiment differs from the first embodiment in that these valves are fixed to a single sliding rod 7 and the equilibrium state of the diaphragm 1 and the downwardly deformed state are used for operating the valve body. A first valve element 8 is fixed below the sliding rod 7 and a second valve element 11 is fixed below the sliding rod 7. The sliding rod 7 is urged by a spring 9 so as to contact the operation piece 6 of the diaphragm 1. Have been.

A fluid pressure on the secondary side C such as an automatic valve A to be controlled is applied to the opening 5, and a flow path 5a
The pressure is guided to the detection chamber 4 provided below the diaphragm, but when the set value shown in FIG. 4 is satisfied and the diaphragm 1 is in an equilibrium state, the sliding rod 7
Both the upper and lower valve elements are set to be “open”, and conduction between the opening 5 and the first opening 13 and between the second opening 14 and the third opening 15 are allowed.

When the pressure in the detection chamber 4 drops below the set value, the diaphragm 1 is deformed from the equilibrium state to a downwardly projecting shape, and the operation piece 6 pushes down the sliding rod 7 against the spring 9. . As a result, the first valve body 8 and the second valve body 11 fixed to the sliding rod 7 descend, and the second valve body 11
Opens between the opening 5 and the first opening 13 and the first valve body 8
Are the second opening 14 and the third opening 1
5 and is displaced to the state of FIG.

FIGS. 12 and 13 show an example in which the pilot valve is used for controlling the automatic valve A and the like. The opening 5 of the pilot valve is connected to the secondary side C of the automatic valve A and the secondary side. The pressure of C is applied to the detection chamber 4 from the opening 5 via the flow path 5a, and applies pressure to the diaphragm 1. Next, the first opening 13 is connected to a discharge port R that is continuous with the space M of the automatic valve A, the primary side B of the automatic valve A is connected to the second opening 14,
The third opening 15 is connected to the opening Z of the space M of the automatic valve A. When the set value is satisfied and the diaphragm 1 is in an equilibrium state in such a connection state, the fluid on the primary side B passes through the second opening 14 and passes from the third opening 15 to the opening Z as shown in FIG.
, The pressure in the space M continues to press the piston G downward, the valve body X shuts off between the primary side B and the secondary side C, and the secondary Maintain side C pressure.

When the pressure on the secondary side C of the automatic valve A falls below the set value of the pilot valve, as shown in FIG.
Is deformed into a downwardly projecting shape, and the operation piece 6 pushes the sliding rod 7 downward against the spring 9, so that the second valve body 1
1 releases the blockage between the opening 5 and the first opening 13, and at the same time blocks between the second opening 14 and the third opening 15 that the first valve body 8 has opened up to that time. Thereby, the fluid supplied to the space M via the opening Z of the automatic valve A from the second opening 14 of the pilot valve via the third opening 15 is shut off, and the fluid in the space M of the automatic valve A is discharged. It flows from the outlet R through the first opening 13 to the secondary side C of the automatic valve A from the opening 5 to reduce the pressure in the space M. As a result, the piston G of the automatic valve A rises, and accordingly, the valve body X is lifted, and the fluid on the primary side B flows into the secondary side C to increase the pressure on the secondary side C toward a set value.

When the pressure on the secondary side C rises to a set value,
The diaphragm 1 in the detection chamber 4 of the pilot valve receiving the pressure shifts to the equilibrium state, all return to the state of FIG. 12, the outflow of the fluid in the space M of the automatic valve A is stopped, and the primary side B Of the second opening 14 and the third opening 1 again.
5 through the opening Z to flow into the space M of the automatic valve A, push down the piston G, thereby lowering the valve body X to shut off between the primary side B and the secondary side C. Even when the pressure on the secondary side C exceeds the set value of the pilot valve and the diaphragm 1 is deformed into a protruding shape, the sliding rod 7, the first valve body 8, and the second valve body 11 are not shown in FIG. 4 and FIG. 12, the automatic valve A remains in the closed state.

[0031]

As described above, according to the present invention, the forced supply of fluid, which was not provided in the conventional pilot valve, can be performed quickly and reliably, so that the automatic valve to be controlled can be quickly and reliably operated. There is an effect that can be done.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a first embodiment of the present invention when a plurality of valves are both closed.

FIG. 2 is a cross-sectional view of FIG. 1 when an upper valve is open and a lower valve is closed.

FIG. 3 is a cross-sectional view of FIG. 1 when an upper valve is closed and a lower valve is open.

FIG. 4 is a cross-sectional view when a plurality of valves are both open in a second embodiment of the present invention.

5 is a cross-sectional view of FIG. 4 when an upper valve is open and a lower valve is closed.

FIG. 6 is a reference diagram showing a relationship between a flow rate and a secondary pressure applied to the first embodiment of the present invention.

FIG. 7 is a reference diagram showing a relationship between a flow rate and a secondary pressure applied to the second embodiment of the present invention.

FIG. 8 is a reference diagram showing a relationship between a flow rate and a secondary pressure applied to a conventional product.

FIG. 9 is an explanatory diagram when the first embodiment of the present invention is combined with an automatic valve, and is a reference diagram showing a flow path when the pressure on the secondary side is at a set value of the pilot valve.

FIG. 10 is a reference diagram showing a flow path when the pressure on the secondary side is lower than the set value of the pilot valve in FIG.

FIG. 11 is a reference diagram showing a flow path when the pressure on the secondary side is higher than the set value of the pilot valve in FIG. 9;

FIG. 12 is an explanatory diagram when the second embodiment of the present invention is combined with an automatic valve, and is a reference diagram showing a flow path when the pressure on the secondary side is at a set value of the pilot valve.

FIG. 13 is a reference diagram showing a flow path when the pressure on the secondary side is lower than the set value of the pilot valve in FIG.

FIG. 14 is a reference diagram in the case where a conventional pressure reducing and opening pilot valve and an automatic valve are combined.

FIG. 15 is a reference diagram when a conventional pressure-opening pilot valve and an automatic valve are combined.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Diaphragm 2 Handle 3 Spring 4 Detection chamber 5 Opening 6 Operation piece 7 Sliding rod 8 Valve 9 Spring 10 Valve rod 11 Second valve 12 Spring 13 First opening 14 Second opening 15 Third opening

Claims (3)

[Claims] A plurality of valves are provided to adjust a flow rate of a plurality of independent systems corresponding to respective states from a case where the pressure of a portion to be controlled increases to a case where the pressure of the portion to be controlled decreases. A pilot valve which is arranged coaxially and is capable of controlling those valves in proportion to a pressure difference from a set value. 2. The pilot valve according to claim 1, wherein all of the plurality of valves are closed at the same time. 3. The pilot valve according to claim 1, wherein all of the plurality of valves are not closed at the same time.