JP4485014B2 - Overflow prevention valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, when the gas flows in an excessive outflow state due to breakage or burning of the gas transport pipe, the valve body is in a state of being separated from the valve seat by the elastic force of a spring or the like, The present invention relates to an overflow prevention valve that seats on a valve seat and closes due to a pressure difference on the downstream side, a fluid circulation pressure, and the like, and prevents fluid from flowing out downstream.
[0002]
[Prior art]
Conventionally, for example, there is an overflow prevention valve disclosed in Japanese Utility Model Publication No. 62-8704. As shown in FIG. 4 , this valve device has a valve seat 2 at one end and a coil spring 8 fitted on the valve seat 2 fixed in the outer cylinder 1 so as to be integrated with the ball valve 6. The connected support rod 9 is projected to the outside of the valve rod 7 through a pair of slits 10 and 10 provided in the axial direction on the valve rod 7 so as to be movable in the axial direction, and the coil spring 8 is supported by the support rod 9. And a downstream end of the valve rod 7. According to this, the pressing force generated by the gas flow acting on the ball valve 6 in the overflow state acts on the coil spring 8 via the support rod 9, acts on this spring 8, compresses the spring, and the ball valve 6 contacts the valve seat 2 as indicated by the dotted line and closes. As described above, in the conventional overflow prevention valve, the ball valve 6 is generally provided in a state of being largely separated from the valve seat 2 during normal fluid flow. For example, an excessive outflow prevention valve used for a gas transport pipe is used in a state of being piped by being sealed in a pipe joint that is sealed in a pipe end or connected to a pipe.
[0003]
[Problems to be solved by the invention]
One of the performances required for these overflow prevention valves is to minimize the flow resistance during normal use. For example, there are spherical, needle-shaped, streamlined, and valve-shaft-integrated valve element shapes for the overflow prevention valve. When installed on a shaft in a passage, fluid often peels behind the valve body and vortices are often generated. The generation of this vortex has a large loss energy when viewed from the entire pipeline system, and it is desirable that the vortex is not present.
In addition, this overflow prevention valve is often mounted at an underground position of piping, and has been used without maintenance for several decades and is in a movable state. Therefore, it is necessary to operate normally for many years, and the size of each member of the overflow prevention valve should not change due to wear or the like. Furthermore, the overflow prevention valve must not malfunction due to changes in the installation direction or gas consumption.
[0004]
By the way, there are mainly two driving forces for shutting off the gas flow in an emergency. One is the pressing force that acts on the valve body due to excessive gas flow at the time of breakage outflow, and the other is the pressure difference between the upstream side and the downstream side that occurs when the downstream pipe breakage is released to the atmosphere. It is. Among these, the pressure difference between the upstream and downstream has the advantage that it can be used for a steep valve closing operation. In other words, the overflow prevention valve has a cross-sectional area (hereinafter referred to as an orifice) through which the narrowest fluid passes, and a pressure difference between the upstream side and the downstream side is caused by this orifice. The smaller the value is, the steeper and better valve closing characteristics can be obtained. However, the smaller the orifice area, the greater the pressure loss during normal flow.
[0005]
The present invention has been made in order to solve the above-described problems. In a normal flow state, the flow resistance is kept as low as possible and can be used for a long time without causing malfunction of the valve body. An object of the present invention is to provide an overflow prevention valve capable of interrupting a fluid flow without delay in an emergency such as breakage.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has a valve seat formed in a cylindrical body case and a valve body that comes into contact with and separates from the valve seat, and the downstream pressure is abnormally reduced. The valve body abuts against the valve seat and closes the passage of fluid, and the valve body has a part of the valve body on the valve seat taper perspective section during normal flow . as is urged by a spring in a direction away from said valve seat, and a supported spheroids in the tubular body case linked radial valve body support portion, surrounded by the valve body and the inner wall The relationship between the cross-sectional area of the fluid and the cross-sectional area of the fluid between the valve body and the valve seat is approximately the same or within plus or minus 10% .

[0007]
Also , a passage groove is provided on the taper surface of the valve seat, and a passage groove is provided on the valve seat so that fluid flows little by little from the upstream side of the valve body when the valve body is seated on the valve seat. can do.
[0008]
[Action]
When the fluid is flowing normally, the taper surface or curved surface forming the valve seat guides when the fluid passes as a result of at least a part of the valve body in the tube axis direction being placed on the transparent section of the valve seat. By acting as a surface, it is possible to suppress the occurrence of separation and vortex and pass through the valve seat portion, thereby significantly reducing the pressure loss when the fluid passes.
Also, during normal flow, set the size of the valve body and valve seat so that the area of the passage orifice of the fluid that passes around the valve body is within the allowable pressure loss of the fluid, and the valve body vibrates. By allowing the valve body to be biased in a direction away from the valve seat with an appropriate elastic force not to flow, the flow-through characteristic during normal flow can be stably obtained. In addition, it is possible to provide an overflow prevention valve without maintenance for many years and without causing the valve body to behave in an unstable manner and causing no malfunction.
[0009]
The passage orifice area of the fluid passing around the valve body is configured to be the narrowest cross-sectional area through which the fluid passes through the overflow prevention valve, and a part of the valve body covers the perspective section of the valve seat taper part. Yes. As a result, for example, in the event of an emergency in which the pipe is broken downstream and fluid is ejected, the valve element is once moved in the valve seat direction against the urging force of the spring, and the orifice area through which the fluid around the valve element passes is continuous. The pressure difference between the upstream side and the downstream side continuously increases, the valve body moves further in the closing direction, contacts and seats on the valve seat surface, and a steep valve closing characteristic can be obtained. Become.
[0010]
In this case, in a state where the inside of the pipe is flowing normally, the fluid passage cross-sectional area between the pipe inner surface and the valve body and the fluid passage cross-sectional area between the valve body and the valve seat are not greatly separated from each other. The flow of fluid that passes around the valve body flows smoothly, the guide action by the valve seat surface works effectively, the generation of vortices when passing through the valve body is suppressed, and the behavior of the valve body due to fluid pressure and fluid pressure Is performed stably, and the valve body does not vibrate or generate abnormal noise.
[0011]
By supporting the valve body with a radial support, the flow resistance of the fluid around the valve body can be reduced. Further, when the valve body is supported in a net state, the fluid is rectified when passing through the net portion, and there is an effect of suppressing the turbulent flow phenomenon of the fluid when passing through the valve body and the valve seat.
Also, when the valve element is seated on the valve seat, it can be structured so that the fluid slightly leaks from the upstream side to the downstream side.In this case, when the repair and repair of the gas ejection point of the downstream pipe is completed, Even if the valve body is closed, fluid flows to the downstream piping, so the downstream pressure increases little by little, and the pressure difference between the upstream and downstream sides of the valve body decreases. Therefore, the closed valve body is separated from the valve seat by the elastic force of the spring, and the valve is opened. Therefore, it is not necessary to manually operate the shutoff mechanism of the overflow prevention valve that is mounted in the embedded state, and the shutoff valve mechanism is automatically restored to the flow state.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to FIGS. 1 to 3 . 1 to 3 are sectional views showing a state in which an overflow prevention valve according to an embodiment of the present invention is enclosed in a pipe, and FIG. 1 is a longitudinal sectional view showing a state during normal flow and a pipe shaft. It is the side view seen from the direction. FIG. 2 is a longitudinal sectional view showing a state in which the valve body 14 starts to move in the valve seat direction in an emergency in which a fluid such as breakage is abnormally ejected into the piping of the downstream side pipe. FIG. 3 is a longitudinal sectional view showing a state in which the valve body is seated on the valve seat during abnormal ejection on the downstream side. 1 to 3, the overflow prevention valve 11 is mounted in, for example, a flow pipe 10 through which gas or the like flows, and the flow pipe 10 is divided into an upstream flow path 12 and a downstream flow path 13. The inner surface is sealed and held with an O-ring 24 and used.
[0013]
The overflow prevention valve 11 is related to the cylindrical body 11a constituting the valve seat 15, the valve body 14, the valve body support portion 17 that is held at a predetermined distance from the valve seat, the spherical valve body 14 and the cylindrical body 11a. The spring 18 is configured to stop and bias the valve body in a direction away from the valve seat.
In FIG. 1 showing a state in which the fluid normally flows in the pipe 10, the spherical valve body 14 is held at a predetermined distance from the valve seat by the valve body support portion 17, and this predetermined distance is at most of the spherical valve body 14. A part of the valve seat 15 is supported at a position corresponding to the valve seat taper perspective section 21 forming the valve seat 15. Further, an orifice 32 having a flow cross section through which a fluid passes with a predetermined distance between the valve seat 15 and the biasing force of the spring 18 is formed. When a pressing force that exceeds the urging force of the spring acts on the valve body 14, the valve body can freely move between the valve seat 15.
[0014]
The valve body support portion 17 is connected to the case 11a, and a spring 18 and a valve body 14 are mounted in the case 11a to connect the support portion 17 to the case 11a. The support portion 17 is provided by a support body 23 that radially expands from the center of the tube axis, and the thickness of the support body 23 is set to the minimum number of shapes and sizes that do not cause a problem in strength. The vertical support 23 is formed in a tripod shape so that the projected area does not affect the cross sectional area of the fluid.
The support 23 may be formed in a quadruped shape so as not to affect the flow resistance through which the fluid passes, or may be provided with a net-like support to hold the valve body 14 at a predetermined distance from the valve seat. . In the case where it is provided by a net-like support, there is an accompanying effect that the fluid is rectified when passing through the net and suppresses the vortex phenomenon of the fluid when passing through the valve body and the valve seat.
[0015]
In the case of FIG. 1, the orifice in the overflow prevention valve 11 in a state where the fluid normally flows is the orifice 31 surrounded by the valve body 14 and the inner wall of the pipe 10 in the case of FIG. The outer diameter of the valve body, the spring force, and the distance from the valve seat 15 are set so that the orifice cross section 31 is urged by an appropriate elastic force of the spring 18 that does not vibrate and the flow resistance is minimized. .
The orifice may be provided at the passage cross section 32 portion between the valve body and the valve seat in a state where the flow resistance during normal flow is kept to a minimum. It is desirable that the relationship between the cross sectional area 31 in the valve body and the pipe and the cross sectional area 32 between the valve body and the valve seat be substantially the same or within ± 10%. If the difference is within plus or minus 10%, the difference in cross-sectional area is not so large that the turbulence phenomenon is suppressed when the fluid passes around the valve body.
[0016]
The proper spring force that presses the valve body away from the valve seat without vibrating the valve body during normal flow prevents fluctuations in the orifice area due to vibration and normal flow performance is obtained. Further, wear of the valve body support portion 17 and the like due to vibration of the valve body 14 is prevented, and stable operation performance is maintained over a long period of time.
During such a normal flow, a part of the valve body 14 is held at such a position that the valve seat taper section is always applied to the see-through section 21 of the valve seat taper. It plays the role of a passing guide. For this reason, generation | occurrence | production of the vortex | eddy_current behind the valve body 14 is suppressed, and the pressure loss of the fluid at the time of normal flow is suppressed.
[0017]
FIG. 2 shows a state in which the valve body 14 starts to leave the valve body support portion 17 when the pipe of the downstream side flow path 13 is broken and fluid is ejected.
At this time, the position of the orifice having the narrowest flow path in the overflow prevention valve 11 is the position of the orifice 32 surrounded by the tapered surface of the valve body 14 and the valve seat 15, and the position of the orifice 31 in the normal flow of FIG. It becomes smaller than the area at. As the orifice area becomes narrower, the pressure difference between the upstream flow path 12 and the downstream flow path 13 gradually increases, which facilitates further movement of the valve body 14 toward the closing side. For this reason, even if the amount of movement of the valve body 14 in the direction of the valve seat 15 is small, a steep valve closing behavior can be achieved when excessive outflow occurs on the downstream side.
[0018]
FIG. 3 shows a state in which the valve body 14 is seated on the valve seat 15. Several passage grooves 33 are provided on the taper surface of the valve seat 15, and fluid flows from the upstream flow path 12 to the downstream flow path 13 so that the valve body 14 does not completely close even if it contacts the valve seat 15. It is made to flow little by little.
As other methods for causing minute leakage, it is also effective to make the surface of the valve body 14 a golf ball-like dimple surface or to provide a small hole in the valve seat 15 leading to the downstream channel.
By allowing the valve body to flow little by little even if it sits on the valve seat in this way, for example, when the restoration work for the abnormal condition of the downstream piping is completed and there is no abnormal leak location, the passage made to the valve seat 15 The upstream fluid gradually flows from the periphery of the groove 33 to the downstream flow path 13, and the pressure in the downstream pipe 13 gradually increases and balances with the pressure in the upstream pipe 12. When the pressure difference between the upstream side and the downstream side falls within a predetermined pressure, the valve element 14 is separated from the valve seat 15 by the repulsive force of the spring 18 and returns to the normal flow state of FIG.
[0019]
【The invention's effect】
As described above, the overflow prevention valve of the present invention prevents the occurrence of vortex flow directly under the valve body in a normal flow state and keeps the flow resistance as low as possible without causing vibration or malfunction of the valve body. Provided is an overflow prevention valve that can be used for a long time and can shut off the flow of fluid without delaying the valve body in an emergency such as a broken tube.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view and a transverse sectional view showing a normal flow according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of the valve body moving according to an embodiment of the present invention.
FIG. 3 is a cross-sectional view of a valve body seated according to an embodiment of the present invention.
FIG. 4 is a cross-sectional view showing a conventional overflow prevention valve.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Pipe | tube 11 Overflow prevention valve 12 Upstream flow path 13 Downstream flow path 14 Valve body 15 Valve seat taper part 16 Valve body seating state 17 Valve body support part 18 Spring 19 Case 21 Valve seat taper see-through section 22 Spring receiver 23 Support Body 24 O-ring 31 Orifice 32 Orifice 33 Passing groove

Claims (2)

The valve body has a valve seat formed in the cylindrical body case and a valve body that contacts and separates from the valve seat, and the valve body contacts the valve seat when the downstream pressure is abnormally reduced. An overflow prevention valve for closing the passage of fluid,
The valve body is biased by a spring in a direction away from the valve seat and connected to the cylindrical body case so that a part of the valve body covers a perspective view of the valve seat taper during normal circulation . A spherical body supported by a radial valve body support ,
The relationship between the cross-sectional area of the fluid surrounded by the valve body and the inner wall of the pipe and the cross-sectional area of the fluid between the valve body and the valve seat is approximately the same or within plus or minus 10%. Prevention valve. The overflow prevention valve according to claim 1 , wherein a passage groove is provided in a tapered surface of the valve seat so that a minute fluid flows from the upstream side to the downstream side when the valve body is seated on the valve seat.

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