JPS5811647B2 - Pressure reducing valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure reducing valve that can always maintain a constant secondary pressure on the downstream side regardless of the primary pressure on the upstream side. This invention relates to a pressure reducing valve that can automatically close and shut off water when pipes, equipment connections, etc. burst due to unforeseen disasters or accidents such as earthquakes or ground subsidence, or when abnormally low pressure occurs due to water leakage.

As conventional pressure reducing valves, those shown in FIGS. 5 and 6 are known.

All of these pressure reducing valves have a cylinder 8 with an upper sliding tube 9 formed at its upper end, which is placed in the valve box 1 directly above the communication hole 4 provided between the water inlet 2 and the water outlet 3 of the valve box 1. A cylinder lid 25 is fixed to the upper end of the cylinder 8, and in the upper sliding tube 9 there is an upper part fixed above the valve rod 11 to which the valve body 5 for opening and closing the communication hole 4 is fixed at the lower end. piston 1
2 is inserted so that it can slide up and down, and has a mechanism that can adjust the force for lifting the piston 12 upward by a spring 17 installed below the upper piston 12. 9 are connected by a pipe 31 with a reverse IE valve 32 and a gate valve 37 installed in the middle, and in the pressure reducing valve shown in FIG. The difference is that the pressure reducing valve shown in FIG. 6 has a valve box structure in which the primary pressure acts in the direction of opening the valve body 5.

By the way, the primary pressure on the water inlet 2 side is Pl, the secondary pressure on the water outlet 3 side is P2 (however, P2<PI), the repulsive force of the spring 17 is W1, the pressure receiving area of the valve body 5 is A1, and the upper piston 12
When the pressure-receiving area of the pressure reducing valve shown in FIG.
The repulsive force W of 7 is expressed by the following formula [■].

PA+PA=PA+W ・・・・・・[I]W-P
, A1+P2 (A2-A1) ...... [■]
In the above formula [■], A1 and A2-A1 are constant, so if the primary pressure P1 is constant, PlA
l is constant, and the repulsive force W of the spring 17 increases or decreases in proportion to the increase or decrease in the secondary pressure P2.

In other words, if the secondary pressure P2 increases, the upper piston 1
2 descends, and conversely, when the secondary pressure P2 decreases, the upper piston 12 rises to the point where the reaction force W of the spring 17 decreases in proportion to it.

Therefore, when the primary pressure P1 is constant, when the secondary pressure P2 increases, the opening of the valve body 5 becomes smaller due to the lowering of the piston 12, and the flow rate decreases, and conversely, when the secondary pressure P2 decreases, the piston 12 rises. As a result, the opening of the valve body 5 becomes larger and the flow rate increases, so that the secondary pressure P2 can be automatically kept almost constant due to this change in the flow rate.

However, if the primary pressure P1 is not constant but changes,
As is clear from the above equation (II), the repulsive force W of the spring increases or decreases under the influence of both the primary pressure P1 and the secondary pressure P2, so even if the secondary pressure P2 increases or decreases, the spring 17 The repulsive force W does not increase or decrease.

In other words, even if the secondary pressure P2 increases or decreases, the piston 12 does not move up or down so that the repulsive force W of the spring 17 increases or decreases in proportion to it.

Therefore, if the primary pressure P1 changes, the secondary pressure P2
Since the degree of opening of the valve body 5 does not change in accordance with the increase or decrease of
The secondary pressure P2 cannot be automatically maintained substantially constant.

On the other hand, in the pressure reducing valve of FIG. 6, the following formula (CI) holds true when it is in a balanced state, and therefore the reaction force W of the spring 17 is the following formula (
IV).

P A+P A, =P A+W ・・・・・・
(1) W=P2A2-(P,-P,2) A1
......[lV') From formula [I■], secondary pressure P2
In order to keep constant, the repulsive force W of the spring 17 must be constantly
It is necessary to set the pressure-receiving area A2 of the upper piston 12 large according to the magnitude of the differential pressure (p, -p2) so that the value is positive.

In other words, in this pressure reducing valve, the primary pressure P1 and the secondary pressure P2
It is necessary to change the diameter of the upper piston 12 according to the differential pressure (pt P2) between the primary pressure P1 and the secondary pressure P2. It is impossible to keep the next pressure P2 almost constant.

Furthermore, the pressure reducing valves shown in FIGS. 5 and 6 have a secondary pressure P
2, it is also impossible to automatically close the valve and shut off the water.

The purpose of this invention is to correct the drawbacks of the conventional pressure reducing valve, and to provide a pressure reducing valve that can always maintain a constant downstream secondary pressure regardless of changes in the primary pressure. It is an object of the present invention to provide a pressure reducing valve that automatically and instantaneously shuts off water in the event of an abnormally low pressure on the downstream side, which is structurally impossible with other pressure reducing valves.

That is, in the conventional pressure reducing valve as described above, the present invention has a lower piston 13 which has the same area as the valve body 5 and is fixed to the valve body 11 at the lower end of the cylinder 8, as shown in FIG. A lower sliding tube 10 that can be slid up and down is formed, and the valve automatically opens when the secondary pressure guided to the gate valve 36 and cylinder 34 between the water inlet 2 and the upper sliding tube 9 becomes below a certain pressure. The main feature is that the pipe 31 is connected by a pipe 29 equipped with an on-off valve 33, and a check valve 32 is installed that automatically shuts off the water when the pressure difference between the water inlet side and the water outlet side exceeds a certain level. The first invention is a pressure reducing valve, and as shown in FIG. An on-off valve 3 that forms a moving tube 10 and is guided to a gate valve 36 and a cylinder 34 between the water inlet 2 and the upper sliding tube 9 and automatically opens when the secondary pressure becomes below a certain pressure.
3 is connected to the pipe 29 in which the on-off valve 3 is installed.
A gate valve 38 is installed between the cylinder 3 and the upper sliding tube 9 to release the pressure water in the upper sliding tube 9, and a gate valve 39 is installed in the cylinder 34 to release air. The second invention provides a pressure reducing valve equipped with a check valve 32 that automatically shuts off water when the pressure difference between the water inlet side and the water outlet side exceeds a certain level.

In the pressure reducing valve of the first invention having the above configuration, the primary pressure on the water inlet 2 side is P and the secondary pressure on the water outlet 3 side is P2 (however, P2<
Pl), the reaction force of the spring 17 is W1, the pressure receiving area of the valve body 5 is A
1. Assuming that the pressure receiving area of the upper piston 12 is A2 and the pressure receiving area of the lower piston 13 is A3, the following formula (V') holds true when in a balanced state, but the pressure receiving area A3 of the lower piston 13 and the valve body are Since the pressure receiving area A1 is equal, the following formula (V
O holds true, and therefore, the repulsive force W of the spring 17 is expressed by the following equation.

P1A1+A2P2-・P1A3+P2A1+W ・・
・[,■]AP=PA+W ・・・[■
]22 21 W=-P2(A2-A1)...(b)
In the above formula, the pressure receiving area of the valve body 5 and the upper piston 1
Since the difference (A2-AI) between the two pressure receiving areas is constant, in the pressure reducing valve of the present invention, the repulsive force W of the spring 17 is equal to the secondary pressure P.
2, and is not affected by the primary pressure P1 at all.

In other words, if the secondary pressure P2 increases, the upper piston 12 descends so that the reaction force W of the spring 17 increases proportionally, regardless of the change in the primary pressure P1, and conversely, the secondary pressure P2 decreases. , the upper piston 12 rises so that the repulsive force of the spring 17 decreases in proportion to this.

Therefore, if the secondary pressure P2 increases, the opening of the valve body 5 decreases in proportion to it, and the flow rate decreases, and conversely, the secondary pressure P2 increases.
2 decreases, the opening of the valve body 5 becomes larger and the flow rate increases, so that the secondary pressure P2 can be automatically maintained at a substantially constant level by this change in flow rate.

In addition, when the secondary pressure drops abnormally, the pressure inside the pipe 31 associated with the water outlet 3 suddenly decreases, and the cylinder 34 also decreases in pressure, and the piston inside the cylinder 34 rises, causing the on-off valve 33 to rise. is opened, and the primary pressure on the upstream side flows through the pipe 29 to the upper sliding tube 9 of the cylinder 8.
The upper piston 12 is guided downward, and the reverse upward valve 3
Guided up to 2.

The valve 32 is designed to close when the pressure difference between the water outlet side and the water inlet side becomes greater than a certain level, so that the escape route for the primary pressure is blocked.

Therefore, since the primary pressure is applied to the upper piston 12, the valve rod 11 is pushed downward and the valve is closed.

Since the elasticity of the spring 17 is set to be smaller than the primary pressure even at its maximum, the valve is completely water-stopped in any case.

The pressure reducing valve of the second invention also functions in exactly the same way as the pressure reducing valve of the first invention, but as described above, the gate valves 38 and 39 are further added to the pressure reducing valve of the second invention. Since the cause of the abnormally low pressure on the downstream side is removed and the water flow is returned to the open state, when the gate valve 36 is closed and the gate valve 38 is opened, the inside of the upper sliding cylinder 9 is removed. As the remaining pressure water is released outside, the pressure on the upper piston 12 is removed and the valve stem 11 is moved upward by the spring 17 to open the water flow valve, and the secondary pressure is passed through the pipe 31. When the air is introduced into the upper sliding cylinder 9, the state before the abnormally low pressure can be easily returned by closing the gate valve 38 and opening the gate valve 36 again, and even if air enters the cylinder 34, Since the gate valve 39 can be opened to remove air, the on-off valve 33 can be operated in accurate response to changes in the secondary pressure.

As described above, the pressure reducing valve of the present invention automatically maintains the secondary pressure constant regardless of the primary pressure, and automatically closes and shuts off the water when the secondary pressure drops abnormally. ,
Even if downstream pipes or equipment connections burst due to unforeseen disasters or accidents such as earthquakes or ground subsidence, or if water leaks, etc., the water supply can be immediately stopped to prevent secondary disasters such as flooding. It can be prevented.

In addition, there is no need to replace springs or cylinders or pistons, and there is versatility in responding to changes in primary pressure, which improves productivity and allows for easy pressure adjustment during use. 33 can be set to any predetermined pressure, so the normal lower limit pressure setting on the downstream side of the pressure reducing valve can be freely selected.

Furthermore, even if a fire occurs on the downstream side and a large amount of water is required for extinguishing the fire, the valve can be fully opened to supply water with an extremely simple operation.

One embodiment of the present invention will be described based on the drawings. As shown in FIGS. 1 and 2, a valve box 1 is provided with a communication port 4 between a water inlet 2 and a water outlet 3. 4 has a valve body 5 housed in the valve box 1 on the side of the water inlet 2 with the communication port 4 as a boundary.
The valve seat 6 is fitted into the valve seat 6, and a valve body guide 7 that does not block water flow is integrally formed with the valve seat 6 at the center of the valve seat 6.

A cylinder 8 is integrally fixed to an opening formed in the valve box 1 above the communication port 4 with bolts or the like.

An upper sliding tube 9 is formed at the upper end of the cylinder 8, and a lower sliding tube 10 is formed at the lower end, and the upper end of the valve stem 11 is fitted into the upper sliding tube 9. The upper piston 12 is fitted so as to be able to slide up and down, and the lower sliding tube 10 has the same pressure receiving area as the valve body 5 fitted near the center of the valve rod 11 with the valve body 5 fitted at the lower end. A lower piston 13 having a lower piston 13 is fitted so as to be slidable up and down.

Then, each piston 12, 13 is covered with a bowl skin 14 on the surfaces facing each other, and the pistons 12, 13 are placed on top
A bowl skin presser 15 is placed on the recess 14 to enable tight sliding movement up and down inside the lower sliding tubes 9 and 10, and to prevent the valve stem 14 from peeling off.
The tightening is fixed at 1.

At the vertical center of the cylinder 8, there is a spring 17 fitted to the valve stem 11 so as to be able to slide up and down, at the lower end of the spring 17, which pushes the upper piston 12 upward. An air hole 20 that is slidably fitted to the valve rod 11 that moves the receiver 18 up and down to adjust the force of the spring 17 pushing up toward the upper piston 12, and that screws and holds an adjustment screw 19 that has a male thread groove on the outer periphery. It has a gripping arm 21 having a hole therein.

Further, a rod hole 22 for rotating and lowering the adjusting screw 19 is formed at the lower end of the adjusting screw 19.

The lower side surface of the gripping arm 21 of the cylinder 8 has the air hole 2
An opening 23 is provided to allow air leaking from the cylinder 8 to escape to the outside of the cylinder 8 and to allow a rod for rotating the adjustment screw 19 to be inserted and rotated.

A valve stem guide 24 for vertically slidably holding the valve stem 11 at the center is fitted into the inner peripheral surface of the opening at the upper end of the valve box 1 at the lower end of the cylinder 8.

Further, a cylinder lid 25 is installed on the upper end surface of the cylinder 8, and a water guide hole 26 and a communication hole 27 are bored in the lid 25, which communicate with the lower surface from both end surfaces of the lid 25, respectively. A pipe 29 is connected to a water intake hole 28 bored in the side wall surface of the valve box 1 on the water inlet 2 side in the gap above the upper piston 12 in the cylinder 9.
On the other hand, water can be led from the water intake hole 30 on the water outlet 3 side of the valve box 1 to the same gap from the communication hole 27 through the pipe 31, and the water in the same gap can be discharged to the water outlet 3 side.

32 is a spring type lift check valve installed near the outlet of the communication hole 27 of the pipe 31, and is normally used to prevent the pressure water in the upper sliding tube 8 from flowing back into the pipe 31; This is a valve that automatically shuts off water when the difference in water pressure between the water inlet side and the water outlet side of the valve 32 exceeds a certain level.

33 is a spring type on-off valve installed in the pipe 29,
The cylinder 34 at the upper part of the volume valve 33 is connected by a pipe 35 to a pipe 31 on the side opposite to the communication hole 27 side of the spring type lift check valve 32, and the pressure at the water outlet 3 of the valve box 1 is abnormal. When the pressure becomes low, the piston in the cylinder 34 moves upward to open the spring-type on-off valve 33 to guide water from the water inlet 2 side into the cylinder 8 through the pipe 29 and the water introduction hole 26.

36 is a gate valve or cock installed between the water inlet 2 of the pipe 29 and the spring-type open/close valve 33; 37 is a gate valve or cock installed between the water outlet 3 of the pipe 31 and the spring-type lift check valve 32; Cock, 38 is a gate valve or cock installed in a pipe branched from between the spring type on-off valve 33 installed in the pipe 29 and the introduction hole 26, 39 is a gate valve or cock installed in the pipe connected to the upper part of the cylinder It is.

Further, on the bottom surface of the valve body 5 facing the water outlet 3, a valve packing 40 and a packing receiver 41 for preventing water leakage are attached to the valve stem 11 by a nut 42.

Further, 43 is a rubber plate for preventing dirt and the like from entering the lower sliding tube 10.

Next, in order to install the pressure reducing valve of the present invention having the above configuration, first, the water inlet 2 is connected to the upstream pipe, and the water outlet 3 is connected to the downstream pipe.

Then, water from the upstream side enters the valve box 1 through the water inlet 2 and applies primary pressure to the lower piston 13 and the valve body 5.

At this time, since the pressure-receiving areas of the lower piston 13 and the valve body 5 are equal, equal forces act on the valve rod 11 in the vertical direction and are canceled out.

When the gate valve 37 is left open, the secondary pressure on the downstream side flows from the water intake 30 of the water outlet 3 through the pipe 31 and the spring lift check valve 32, and from the communication hole 27 to the upper sliding tube 9 of the cylinder 8. The upper piston 12 is pushed downward by the
Since the piston 12 is pushed upward by the spring 17, it comes to rest at a fixed point.

When increasing the secondary pressure, the adjustment screw 19 is moved upward to strengthen the elasticity of the spring 17 applied to the upper piston 12 from below.

Then, the upper piston 12 moves upward, and therefore the valve stem 1
1 also moves upward, so the gap between the valve body 5 and the valve seat 6 becomes larger, allowing a large amount of water to flow downstream from the communication port 4 and increasing the secondary pressure.

At this time, the secondary pressure also acts to push the upper piston 12 downward and remains at 1, but the spring 17 causes it to stop at a certain point.

Conversely, when lowering the secondary pressure, the adjustment screw 19 is moved downward to weaken the elasticity of the spring 17 applied to the upper piston 12 from below.

Then, the upper piston 12 moves downward and the valve stem 11 also moves downward, so the gap between the valve body 5 and the valve seat 6 becomes smaller, and the amount of water from the communication port 4 decreases, making it possible to lower the secondary pressure. can.

In this way, according to the pressure reducing valve of the present invention, it is possible to obtain a reduced secondary pressure completely independent of the primary pressure on the upstream side, so that a constant water pressure can always be obtained on the downstream side.

Next, a case where the secondary pressure on the downstream side has abnormally decreased will be described.

When the gate valves 36 and 37 are open, the gate valves 38 and 39 are closed, and the water flow valve is open (the state shown in Fig. 1), if the downstream secondary pressure suddenly decreases, it will connect to the water outlet 3. Pipe 31
The pressure within the cylinder 34 suddenly decreases, and the pressure within the pipe 35 connected to the same pipe 31 also decreases, causing the cylinder 34 to also decrease in pressure.As a result, the piston within the cylinder 34 rises, causing the spring-type on-off valve 33 to open. The primary pressure on the upstream side is guided from the water introduction hole 26 to the upper sliding tube 9 of the cylinder 8 through the pipe 29, presses the upper piston 12 downward, and passes through the communication hole 27 to the spring-type lift check valve 32. be guided.

Since the volume valve 32 is designed to close when the pressure difference between the water outlet side and the water inlet side becomes larger than a certain level, the escape route for the primary pressure is blocked.

Therefore, since the primary pressure is applied to the upper piston 12, the valve stem 11 is pushed downward and the valve is closed.
(Situation shown in Figure 2).

Since the elasticity of the spring 17 is set to be smaller than the next pressure even at its maximum, the valve is completely shut off in any case.

When the cause of the abnormally low pressure on the downstream side is removed and the water flow valve is returned to the open state, the gate valve 36 is closed and the gate valve 38 is opened.

Then, the pressure water remaining in the upper sliding tube 9 is released outside, so the pressure on the upper piston 12 is removed, and the valve rod 11 is moved upward by the spring 17 to open the water flow valve. When the secondary pressure is introduced to the upper sliding cylinder 9 through the pipe 31, the gate valve 38 is closed again.
By opening 6, it returns to the state before the abnormally low pressure and can be used as a normal pressure reducing valve.

At this time, the spring-type on-off valve 33 is automatically closed and shut off again due to the secondary pressure being applied to the cylinder 34 to prevent the primary pressure from entering the cylinder 8 .

That is, only secondary pressure is acting within the upper sliding cylinder 9.

The gate valve 37 is used to maximize the water flow by maximizing the distance between the valve body 5 and the valve seat 6.
is simultaneously closed and the gate valve 38 is opened to release the pressure water in the upper sliding cylinder 9 to the outside, the upper piston 12 is moved upward by the spring 17, and therefore the valve body 5 is also moved upward.

The gate valve 39 is for venting air. According to this invention, if the secondary pressure on the downstream side becomes abnormally low, the valve completely shuts off the water, so downstream pipes and equipment connections are protected against earthquakes, ground subsidence, etc. This system prevents secondary disasters such as floods by automatically and instantaneously closing the valve and completely shutting off water in the event of an unexpected disaster or accident causing a rupture or abnormally low pressure caused by a water leak. be.

Furthermore, according to this invention, even if a fire occurs downstream and a large amount of water is required for extinguishing the fire, the valve can be fully opened and filled with water with an extremely simple operation. There are significant advantages compared to valves.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention. FIG. 1 shows the state when the water flow valve is open, FIG. 2 shows the state when the water cutoff valve is closed, and FIGS. 4 is an explanatory diagram of the present invention, and FIGS. 5 and 6 are explanatory diagrams of a conventional example. 1...Valve box, 2...Water inlet, 3...Water outlet, 4...Communication hole, 5...Valve body, 8...Cylinder, 9...Upper sliding tube, 10...Lower sliding tube , 11...Valve stem, 12...Upper piston, 13...Lower piston, 17...Sprink,
25... Cylinder lid, 29... Pipe, 31... Pipe, 32... Check valve, 33... Open/close valve, 34... Cylinder, 38... Gate valve, 39... Gate valve.

Claims (1)

[Claims] 1. Communication hole 4 provided between water inlet 2 and water outlet 3 of valve box 1
A cylinder 8 having an upper sliding tube 9 formed at its upper end is fixed to the opening hole of the valve box 1 directly above the cylinder 8, and a cylinder lid 25 is fixed to the upper end of the cylinder 8. In this case, an upper piston 12 fixed above a valve rod 11 having a valve body 5 fixed to the lower end for opening and closing the communication hole 4 is inserted so as to be able to slide up and down, and a spring 17 installed below the upper piston 12 The cylinder 8 is a pressure reducing valve which has a mechanism that can adjust the force of lifting the piston 12 upward, and in which the water outlet 3 and the upper sliding tube 9 are connected by a pipe 31 with a gate valve 37 installed in the middle. A lower sliding cylinder 10 having the same area as the valve body 5 at the lower end and allowing a lower screw 13 fixed to the valve stem 11 to slide up and down.
A gate valve 36 is installed between the water inlet 2 and the upper sliding tube 9.
and connected by a pipe 29 equipped with an on-off valve 33 that automatically opens when the secondary pressure led to the cylinder 34 falls below a certain pressure, and the pressure difference between the inlet side and the outlet side of the pipe 31 is above a certain level. This is a pressure reducing valve equipped with a check valve 32 that automatically shuts off water when the water stops. 2 Communication hole 4 provided between water inlet 2 and water outlet 3 of valve box 1
A cylinder 8 having an upper sliding tube 9 formed at its upper end is fixed to the opening of the valve box 1 directly above the cylinder 8, and a cylinder lid 25 is fixed to the upper end of the cylinder 8. An upper piston 12 fixed above a valve rod 11 to which a valve body 5 for opening and closing the communication hole 4 is fixed at the lower end thereof is inserted so as to be able to slide up and down, and a spring 17 installed below the upper piston 12 The pressure reducing valve has a mechanism that can adjust the force for lifting the piston 12 upward, and the water outlet 3 and the upper sliding tube 9 are connected by a pipe 31 with a gate valve 37 installed in the middle. A lower sliding tube 10 having the same area as the valve body 5 and in which a lower piston 13 fixed to the valve stem 11 can slide up and down is formed at the lower end of the valve 8, and the water inlet 2 and the upper sliding tube 9 are connected in the middle. The gate valve 36 and the cylinder 34 are connected by a pipe 29 equipped with an on-off valve 33 that automatically opens when the secondary pressure guided to the cylinder 34 becomes lower than a certain pressure, and the on-off valve 33 and the upper sliding cylinder are connected to each other by a pipe 29. 9
A gate valve 38 that can release pressure water in the upper sliding tube 9 between
A gate valve 39 is installed in the cylinder 34 to release air, and a check valve 32 automatically shuts off water when the pressure difference between the inlet side and the outlet side of the pipe 31 exceeds a certain level. A pressure reducing valve with a 3. The pressure reducing valve according to claim 1 or 2, wherein the on-off valve 33 is a spring-type on-off valve.