JPH037650Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in ball valves, particularly plastic ball valves.

A plastic ball valve (see FIG. 1) whose main components include a valve body, a ball, a union, a body cap, a cap nut, etc. is widely known from Japanese Utility Model Publication No. 53-9951 filed by the present applicant. However, in this type of known ball valve, the unions are inserted from both ends of the valve body, but the unions themselves are not fixed to the valve body, so it is difficult to remove the cap nut from the valve body while the valve is closed. In some cases, fluid pressure can cause the ball and union to pop out of the valve body.
Therefore, when installing or replacing the piping connected to the fluid outflow side of the ball valve, inspecting the inside of the pipe, or inspecting the ball surface with the valve closed, there is a possibility that the ball may fly out and cause fluid to flow out. It turned out to be sexual.

The first method to prevent the ball from popping out due to fluid pressure when removing the cap nut on the fluid outflow side when the valve is closed is to adhere the union to the valve body, and to use a groove formed in the valve body with a claw provided on the union. There is a second method in which the union is prevented from coming off by engaging with the valve body, and a third method in which the two unions are screwed onto the valve body (see Japanese Patent Publication No. 53-6375). However, when using the first method, it is impossible to inspect the ball surface or replace the seat member, so if the valve breaks down, the entire valve must be replaced, which is uneconomical. . Furthermore, in the case of the second method, the engagement between the union and the valve body may become insufficient, so it is not possible to completely prevent the ball and the union from popping out. Furthermore, although the third method has the effect of preventing the ball and union from popping out, there is a problem in that it takes time to assemble the valve. In addition, by screwing the two unions from both sides of the valve body, the seat members provided on both unions are pressed against the ball, so variations in the tightening force of the ball by both unions may cause the ball to shift from the center of the valve body. However, there is a problem in that the handle torque increases when opening and closing the valve.

On the other hand, in conventional ball valves, a rubber-like elastic body is used for the seat member provided between the valve body, union, etc. and the ball.
When using a rubber-like elastic body, it was found that the ball and the rubber-like elastic body would seize during long-term use, resulting in an increase in handle torque and difficulty in opening and closing the valve. Sheet members made of surface-active hard plastics such as tetrafluoroethylene have begun to be used in place of rubber-like elastomers. In the case of a hard plastic sheet member, the above-mentioned operational problems do not occur even after long-term use, but the adhesion between the sheet member and the ball decreases due to wear of the sheet member and the ball. There is a problem that sealing performance is reduced.

On the other hand, Japanese Patent Publication No. 46-38475 discloses a ball valve equipped with a seal ring and an elastic reinforcing ring. In this known ball valve,
The retaining ring is supported by a fixed ring that is fitted into the inner circumferential groove of the valve body, and the seal ring is supported by this retaining ring via an elastic reinforcing ring. The inner peripheral surface of the seal ring that contacts the ball is not engaged with the stop ring.
For this reason, when fluid pressure in the flow path acts on the seal ring through the ball, part of the pressure applied to the seal ring escapes into the flow path, and the force that presses the elastic reinforcement ring in the axial direction is weakened accordingly. Become. Therefore, conversely, the force with which the elastic reinforcing ring pushes the seal ring back toward the ball becomes weaker, and the adhesion force of the seal ring to the ball decreases.
Also, when the ball is rotated by the handle, force is applied to the seal ring inward to the flow path.
In the case of the above-mentioned ring holding structure, the ring holding force against such force may be insufficient, and there is a possibility that the seal ring or the elastic reinforcing ring may protrude into the flow path. Moreover, a special tool is required to engage the fixing ring with the inner circumferential groove of the valve body, making it troublesome to replace seal rings, elastic reinforcing rings, balls, etc. This has the disadvantage that the number of parts increases.

As a means to solve the above-mentioned problems, the present invention forms a fluid flow path that opens at both ends in the valve body, and has a flow path opening/closing valve that is turned by a handle operation in the fluid flow path. A ball is provided, a ring-shaped union having an outer periphery flange is screwed into one end opening of the valve body, and a seat packing is interposed between the outer periphery flange of the union and one end of the valve body. , an annular stepped portion facing the ball is formed on the inner wall of the other end of the valve body, and an axial direction is formed between the inner end of the union facing the ball and the stepped portion in the valve body. A surface-activated ring groove having a generally rectangular cross section is provided with openings toward the ball side, and the ring groove is in close contact with the large-diameter side circumferential wall surface and the small-diameter side circumferential wall surface of the ring groove and abuts against the ball. The present invention provides a ball valve characterized in that a hard plastic seat ring is mounted, and a rubber-like elastic ring is interposed between the seat ring and the bottom of the ring groove.

According to the above means according to the present invention, both the seat ring and the elastic ring that come into contact with the ball are supported by the large-diameter side circumferential wall surface and the small-diameter side circumferential wall surface of the ring groove, which has a generally rectangular cross-sectional shape in the axial direction. Therefore, the seat ring transmits almost all of the fluid pressure acting on the seat ring through the balls to the elastic ring as an axial force without letting it escape to the inside of the flow path. Since the elastic ring that has received this pressure cannot release the pressure to the outside from the ring groove, all of that pressure is used as a repulsive elastic force, which in turn acts to press the seat ring against the ball. Therefore, the adhesion of the seat ring to the ball can always be kept large, and good sealing performance can be maintained.

Hereinafter, an embodiment of the present invention will be described with reference to FIG. 2 of the drawings.

In FIG. 2, 10 is a substantially hollow cylindrical valve body (hereinafter referred to as the main body), and a hollow cylindrical union 11 is provided at one end opening thereof. A flow path is formed inside the main body 10 and the union 11. An outer periphery flange 11A is formed on the outer periphery of the union 11 on the outer end side, and an annular groove 11B is formed on the outer periphery of the inner end side of the union 11. Between the annular groove 11B and the flange 11A, a threaded portion 11C is formed on the outer periphery of the union 11 to be screwed into a threaded portion 10A formed on the inner periphery of the opening at one end of the main body 10. A sheet packing 12 is interposed between the flange 11A of the union 11 and one end of the main body 10, and this sheet packing 12 is inserted between the flange 11A and the main body 10 by screwing the union 11 into the main body 10. It is designed to be held under pressure between the two. Annular groove 11 of union 11
An O-ring 13 is attached to B. This O
- the ring 13 prevents fluid leakage between the body 10 and the union 11; Here, a pair of notched grooves 11D are formed on the inner periphery of the outer end surface of the union 11, and by engaging a tool in both notched grooves 11D and rotating the union 11, the union 11 can be easily screwed into and removed from the main body 10. I am now able to do it.

An annular groove 11E is formed in the outer end surface of the union 11, and an O-ring 14 is mounted in this annular groove 11E. A first body cap 15 is fixed to a pipe (not shown), and the first body cap 15 is connected to the union 11 via an O-ring 14.
It is possible to come into contact with the outer end surface of. A threaded portion 10B is formed on the outer periphery of one end of the main body 10,
The first body cap 15 is removably fastened to one end of the main body 10 via the union 11 by a first cap nut 16 screwed into the threaded portion 10B.

An annular groove 10D is formed in the other end surface of the main body 10, and an O-ring 17 is mounted in this annular groove 10D. A second body cap 18 is fixed to a pipe or the like (not shown), and the second body cap 18 can come into contact with the other end surface of the main body 10 via an O-ring 17. A threaded portion 10C is formed on the outer periphery of the other end of the main body 10, and the second body cap 18 is removably fastened to the other end of the main body 10 by a second cap nut 19 that is screwed into the threaded portion 10C. It is becoming more and more common.

A ball 20 for opening and closing the flow path is provided inside the main body 10. The ball 20 is connected to a handle 22 via a stem 21, and a hole 20A for forming a flow path is formed in the center of the ball 20.
By rotating the ball 20 together with the stem 21 using the handle 22, the flow path can be opened and closed. Annular groove 21 formed in stem 21
An O-ring 23 is attached to A to prevent fluid from leaking between the stem 21 and the main body 10.

Ring grooves 10E and 11F are formed in the main body 10 and the union 11, respectively, and extend in the circumferential direction of the flow path, and surface-activated hard plastics are formed in both ring grooves 10E and 11F, respectively, to be in contact with the circumferential surface of the ball 20. Rubber-like elastic rings 26 and 27 are interposed between these seat rings 24 and 25 and the bottoms of the ring grooves 10E and 11F, respectively. To explain in more detail, the inner wall surface of the other end of the valve body 10 has a stepped portion 10 facing the ball 20.
Ring grooves 10E and 11F, each having a generally rectangular cross section in the axial direction, are formed in the stepped portion 10F and the inner end of the union 11 so as to open toward the ball 20. There is. Seat rings 24, 25 and elastic rings 26, 2 are provided in these ring grooves 10E, 11F.
7 are fitted, and the seat ring 2
The outer circumferential surfaces and inner circumferential surfaces of the elastic rings 4 and 25 and the elastic rings 26 and 27 are supported by the large-diameter side circumferential wall surface and the small-diameter side circumferential wall surface of the ring grooves 10E and 11F, respectively.

Therefore, the seat rings 24, 25 transmit almost all of the fluid pressure acting on the seat rings 24, 25 through the balls 20 to the elastic rings 26, 27 in the axial direction without releasing it to the inside of the flow path. Convey it as power. Then, the elastic rings 26 and 27 that received the pressure transfer the pressure to the ring groove 1.
Since the pressure cannot be released to the outside from 0E and 11F, all of the pressure is used as a repulsive elastic force, and conversely acts to press the seat rings 24 and 25 against the ball 20. Therefore, the adhesion force of the seat rings 24, 25 to the ball 20 can always be kept large, and good sealing performance can be maintained. In addition, when the union 11 is tightened or when the ball 20 is rotated by operating the handle, the seat rings 24, 25, the elastic ring 26,
27 is reliably prevented from protruding into the flow path.

As the material for the seat rings 24 and 25, for example, polytetrafluoroethylene can be used. Further, as the material for the rubber-like elastic rings 26 and 27, for example, backing rubber can be used.

Main body 10, union 11, body cap 1
5, 18, cap nut 16, 19, ball 2
0 and handle 22 are made of plastic.

In the above embodiment, the union 11 is
0, the union 11 can be removed from the main body 10 when inspecting the surface of the ball 20. Further, since the ball 20 is normally pressed against the seat ring on the downstream side by fluid pressure, the seat ring on the downstream side tends to wear out quickly.
Therefore, if the union 11 side is set on the downstream side, the seat ring 25 on the downstream side can be easily replaced by removing the union 11.

When the union 11 is set on the downstream side, the ball 20 is closed and the ball 2
If the first cap nut 16 on the downstream side is removed from the main body 10 while applying fluid pressure to It will not jump out from the main body 10.

In the above embodiment, since the union 11 is screwed onto the main body 10 via the seat packing 12, it is possible to tighten it further. Therefore, the contact pressure between the seat rings 24, 25 and the ball 20 can be adjusted, and good sealing performance can always be maintained. In addition, the seat packing 12 functions to alleviate the stress transmitted from the pipeline and prevent excessive force from being applied to the ball 20.
Damage to the ball 20 is less likely to occur.

In the above embodiment, when the ball 20 is rotated to close the valve, fluid pressure is applied to the ball 20 from the upstream side, and the ball 20 tends to separate from the seat ring 24 or 25 on the upstream side.
Depending on the elasticity and thickness of the upstream rubber-like elastic ring 26 or 27, the upstream seat ring 24 or 2
5 is always pressed against the ball 20, the upstream seat ring 24 or 25 and the ball 20 are kept in close contact, and the sealing performance is maintained normally.
It goes without saying that the seal between the ball 20 and the seat ring 24 or 25 on the downstream side is maintained normally. In addition, due to long-term use, the ball 2
Even when the seat rings 24 and 25 are worn out, the ball 20 and the seat ring 2 are held together by the pressing action of the rubber-like elastic rings 26 and 27.
4 and 25 is maintained normally. The rubber-like elastic rings 26 and 27 also serve to prevent the ball 20 from shifting from the center of the main body 10. That is, the ball 20 is pushed into the main body 1 by the pressure of the fluid.
If the seat ring 24 is deviated from the center position of
25 acts to push the ball 20 back to its original position, and as a result, the ball 20 is always held at the center of the main body 20. On the other hand, since the seat rings 24 and 25 that come into contact with the ball 20 are made of surface-active hard plastic such as polytetrafluoroethylene, the ball 20 and the seat ring
4 and 25, there is no risk of burn-in.

As is clear from the above explanation, according to the present invention, since the union is screwed onto the main body, the union side is set as the downstream side, and the ball is in the closed state, and fluid pressure is applied to the ball while the union side Even if you loosen the cap nut or remove it from the main body, the balls and unions will not pop out from the main body. Moreover, since the union is provided only on one end side of the main body, there is no possibility that the ball will be displaced from the center position of the main body due to screwing of the union. In addition, the seat ring that comes into contact with the ball is made of surface-activated hard plastic, and a rubber-like elastic ring is interposed between the seat ring and the bottom of the mounting groove, and the union is increased by the seat packing. Since the structure allows tightening, it is possible to provide a ball valve that can maintain good sealing performance over a long period of time. In particular, in the present invention, both the seat ring and the elastic ring that come into contact with the ball are supported by the large-diameter side peripheral wall surface and the small-diameter side peripheral wall surface of the ring groove, which has a generally rectangular cross-sectional shape in the axial direction. It is possible to provide a ball valve that can reliably prevent the seat ring and the elastic ring from protruding inward into the flow path, constantly maintain a large adhesion force of the seat ring to the ball, and maintain good sealing performance. Become.

[Brief explanation of the drawing]

FIG. 1 is a partially longitudinal sectional front view showing a conventional ball valve, and FIG. 2 is a longitudinal sectional view of a ball valve showing an embodiment of the present invention. 10...Valve body, 11...Union, 10
E, 11F...Ring groove, 12...Seat packing, 15...1st body cap, 16...1st
Cap nut, 18...Second body cap,
19...Second cap nut, 20...Ball,
24, 25... Seat ring, 26, 27... Rubber-like elastic ring.

Claims (1)

[Claims for Utility Model Registration] A fluid flow path that opens at both ends is formed in the valve body, and a ball for opening and closing the flow path that is rotated by a handle operation is provided in the fluid flow path, the valve body A ring-shaped union having an outer periphery flange is screwed into one end opening, and a seat packing is interposed between the outer periphery flange of the union and one end of the valve body, and the other end of the valve body An annular stepped portion facing the ball is formed on the inner wall of the valve body, and a ring groove having a generally rectangular cross section in the axial direction is formed at the inner end of the union facing the ball and the stepped portion in the valve body. are provided with openings on the ball side, respectively, and a surface-activated hard plastic seat ring is provided in the ring groove in close contact with the large-diameter side circumferential wall surface and the small-diameter side circumferential wall surface of the ring groove and abuts on the ball. What is claimed is: 1. A ball valve, comprising: a rubber-like elastic ring interposed between the seat ring and the bottom of the ring groove.