JPH11148566A - Ball valve made of synthetic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ball valve made of a synthetic resin which ensures a good sealing performance for a long period of time by preventing seat rings from creep deterioration at the time of valve opening, and precluding deterioration of the sealing performance caused by foreign matters contained in a fluid. SOLUTION: This ball valve made of a synthetic resin is composed of a spherical valve element 20 provided with a through hole 21 and having a spherical outer surface, seat rings 40 installed opposingly on both sides of the valve element 20, a valve casing 10 made of a thermoplasstic resin in which the seat rings 40 and the valve element 20 are accommodated, and a valve stem 30 which is fitted in the upper part of the valve element 20, wherein the passage in the valve casing 10 is opened and closed by rotating the valve element 20. In this ball valve, the spherical outside surface of the valve element presses the seat rings 40 on both sides to establish sealing when the valve is closed and a ring-shaped groove 24 is furnished at the spherical outside surface of each end part on the through hole side of the valve element 20, and the grooves 24 accommodate the seal part 43 of each seat ring 40 when the valve is open fully.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin ball valve mainly used for buried piping for transporting a fluid such as gas or water, and more particularly to a seat ring pressing force required for sealing when the valve is closed. Synthetic resin ball having good sealing properties over a long period of time, while preventing the seat ring from creeping at the time of valve opening and preventing the sealing property at the time of valve closing from being impaired by foreign matters in the fluid. It is about a valve.

[0002]

2. Description of the Related Art Conventionally, there is a synthetic resin ball valve shown in FIG. 6 disclosed in Japanese Patent Application Laid-Open No. Hei 9-210225 by the present applicant. The seat 5 has a ball valve body 2 mounted rotatably at the lower and upper parts of a valve box 1 and a dimension between the axial surfaces of the ball valve body 2 in the axial direction of the through-hole on both sides of the valve body 2. 5 is smaller than the plane-to-plane dimension, so that when the valve is fully opened, the ball valve body 2 does not come into contact with the seats 5, 5 to prevent the seats 5, 5 from being constantly subjected to compressive deformation and deteriorated by creep. The sealability and the operability of rotating the ball valve body are improved. There is also a ball valve for gas disclosed in Japanese Utility Model Laid-Open No. 61-11064. As shown in FIG. 7, when the valve is closed, a portion of the spherical outer surface that comes into contact with the seat 4 of the ball valve body 3 when the valve is opened is cut so as to have a spherical surface with a steeper curve than the other portions. A relief surface 7 is provided on the flow channel 8a side so that the contact area with the seat 4 is further reduced, and as shown in FIG.
A relief surface 7 is provided on the side of the flow channel 8a so as to reduce the contact area with the sheet 4 by cutting off one end of a portion contacting with the sheet 4, thereby reducing the contact area applied to the sheet 4.

[0003]

However, there are cases where various foreign matters such as sand, steel chips and fibers are mixed in the fluid in the pipe such as water and gas. In the prior art shown in FIG. During the passage of the fluid through the valve, these foreign matters may be caught in the gap between the valve body 2 and the sheet 5 and accumulated. In the conventional examples shown in FIGS. 7 and 8, the valve body presses the seat ring with the same force when the valve is opened and when the valve is closed. Even when the valve is used in the normal open state, the seat ring may be deteriorated by creep. On the other hand, if the force with which the valve body presses the seat ring is reduced to prevent creep deterioration, the sealing performance when the valve is closed will be affected. In addition, foreign matter in the fluid may be caught and deposited on the relief surface 7 on the flow channel 8a side.

If the valve bodies 2 and 3 are rotated in a state where the foreign matter is caught, foreign matter in the fluid is caught between the valve bodies 2 and 3 and the seats 4 and 5 and sealing is not performed. In addition, the sealing surfaces of the seats 4 and 5 may be damaged, and the spherical outer surfaces of the resin ball valves 2 and 3 may be damaged. The present invention solves the above-described problems, secures a pressing force against a seat ring necessary for sealing when the valve is closed, and prevents creep deterioration of the seat ring when the valve is opened. Provided is a synthetic resin ball valve that prevents a foreign substance in a fluid from being caught between seat rings and impairs sealing performance, and obtains good sealing performance for a long time.

[0005]

SUMMARY OF THE INVENTION The gist of the present invention is to provide a spherical valve body having a through hole and a spherical outer surface, a seat ring disposed on both sides of the spherical valve body so as to face each other, A valve box made of a thermoplastic resin in which a spherical valve body is housed, and a valve rod that engages with the upper part of the spherical valve body and protrudes to the upper part of the valve box. In a ball valve that rotates to open and close a flow path in a valve box, when the valve is closed, a spherical valve body and a seat ring are provided so that the spherical outer surface of the spherical valve body presses and seals the seat rings on both sides. An annular groove is provided in the spherical outer surface at both ends on the through hole side of the spherical valve body, and when the valve is fully opened, the annular groove accommodates a seal portion of a seat ring. It is.

In this case, when the valve is fully opened, both ends of the spherical outer surface project toward the inner peripheral side of the seat ring, and an annular concave groove for accommodating the seal portion of the seat ring is provided on the spherical outer surface. it can. Further, when the valve is fully opened, the annular groove accommodates the seal portion of the seat ring, and the pressing force of the seat ring when the valve is closed can be opened in the annular groove to reduce the force. When the valve is fully opened, the annular groove can be accommodated with a slight gap formed with the seal portion of the seat ring.

[0007]

According to the present invention, the seat ring mounted in the valve box when the valve body is fully opened is accommodated in an annular groove provided on the spherical outer surface of the valve body on the through hole side. Therefore, the annular groove covers the inner peripheral side of the seat ring for accommodating the seal portion of the seat ring, so that there is no gap or escaping surface where foreign matter is caught in the fluid flow path as in the related art. In addition, the pressing force of the seat ring when the valve is closed is released in the annular groove and reduced. Therefore, the pressing force of the seat ring required for sealing when the valve is closed is secured, and the creep of the seat ring is eliminated, so that the sealing performance when the valve is closed is improved. Therefore, foreign matter in the fluid does not accumulate between the spherical valve body and the seat ring,
Good sealing surface pressure and sealing surface accuracy of the valve element and the seat ring are maintained over a long period of time, and good sealing properties are obtained.

Further, in the case of a large-diameter synthetic resin ball valve, a plurality of valve box members divided in the axial direction of the flow path are provided due to a problem in molding the valve box body by injection molding. A manufacturing method of forming an integrated valve box by fusing the butt is adopted. When this valve box is formed by butt fusion, in the present invention, the spherical valve body to be mounted in the valve box is mounted in a fully opened state and the valve box members are butt-fused together, thereby forming a seat ring on both sides. The fusing operation is performed in a state where the compression deformation applied to the seat ring is small or not compressed, with the through passage of the valve body as the axis. For this reason, compared to the conventional case where the butt is fused in a state where the seat ring is subjected to the compressive stress with the same force as when the valve is closed, the valve box members are butt-bonded without being affected by the compressive stress of the seat ring. It is possible to fuse, and in the fusion process, there is no conventional problem that the valve core is deformed by the repulsive force against compression or the dimension between the valve box members is expanded and the fusion is performed, and the shafts of the valve box members are combined. Accurate butt welding can be performed by matching both the core and the face-to-face dimensions.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view of a ball valve showing a first embodiment of the present invention. In this embodiment, the valve box 10 is a valve box formed by injection molding of a thermoplastic resin.
1, the spherical valve body 20 and the valve stem 30 are mounted, the seat rings 40, 40 are mounted on the left and right valve box connecting members 12, 13, and the through holes 21 of the spherical valve body 20 are inserted into the valve box connecting members 12, 1, 1.
In a fully opened state corresponding to the third flow paths 14 and 15, the valve box central member 11 and the valve box connecting members 12 and 13 are butt-fused in the axial direction to form an integral valve box 10. This valve box 1
0 may be provided by fusing a valve box member divided in the axial direction into two parts, or provided as an integral valve box having an opening for inserting a valve body at an upper part, and a lid member at an upper opening. May be provided by fusing.

The spherical valve body 20 has a through hole 21 in the center and engages the lower end of the valve rod 30 with the upper side engaging hole 23 of the spherical outer surface 22 to rotate the handle 31 attached to the upper part of the valve rod 30. As a result, the valve body 20 is rotated 90 degrees to open and close the flow paths 14 and 15 on both sides of the valve box. Both ends of the spherical outer surface 22 of the valve body project toward the inner peripheral side of the seat rings 40, 40, and annular concave grooves 24 are provided on both sides of the spherical outer surface 22. The seat ring 40 mounted in the seat mounting groove 16 in the valve box 10 is made of an elastic body such as nitrile rubber in which a reinforcing ring 41 is cast, and a seal abutting on the spherical outer surface 22 of the valve body 20. The portion 43 is provided in an arc-shaped cross section.

As shown in FIG. 2, when the spherical valve element 20 is closed, the seal portion 43 of the seat ring 40 abuts against the spherical outer surface 22 of the valve element with a squeezing margin 44 and is pressed. A seal is provided between the outer surface 22 and the inner surface of the valve box 10. As shown in FIG.
In the fully opened state in which the through hole 21 is in communication with the flow paths 14 and 15 of the valve box by rotating 90 degrees from the valve closed state, the spherical outer surface 2
The sealing portion 4 of the seat ring is inserted into the annular groove 24 provided in
3, the pressing force of the seat ring when the valve is closed is released in the annular groove 24 and decreases to return to a shape close to a free state. In this fully opened state, as shown in FIG. 3, the annular groove 24 comes into contact with the inner surface of the seal portion 43 of the seat ring 40, and the pressing force at the time of closing the valve is released by about 50%. May be provided. Further, as shown in FIG. 4, a slight gap may be formed with the entire seal portion 43, and the seal portion 43 may be provided in the shape of the annular groove 24 in which the entire pressing force at the time of closing the valve is opened. Further, as shown in FIG. 5, a gap may be provided on the inner peripheral flow path side of the seal portion 43 and provided on the outer peripheral side of the valve body, and the annular groove 24 may be provided in the shape of the annular groove 24 that opens only the pressing force in the flow path axial direction. Good.

As described above, in the seat ring 40 mounted in the valve box when the valve is opened, the sealing portion 43 due to the pressing force at the time of closing the valve is reduced by the annular concave groove 24 provided in the spherical outer surface 22 of the valve body. The seal portion 43 is accommodated in the annular groove 24, and the end surface of the valve body 20 on the through hole 21 side projects toward the inner peripheral side of the seat ring 40 to cover the inner peripheral surface of the seal portion 43 of the seat ring. . For this reason, a gap or a relief surface where foreign matter is caught in the flow path in the valve box as in the related art is eliminated. In addition, since the pressing force of the seat ring necessary for sealing at the time of closing the valve is secured and the pressing force of the seal portion 43 is opened in the annular groove 24 at the time of opening the valve, there is a problem of sealing performance due to foreign matter caught in the fluid. And the creep of the seat ring when the valve is closed is eliminated, and a good seal can be obtained over a long period of time.

In this embodiment, the valve box center member 11 and the left and right valve box connecting members 12 and 13 divided in the axial direction of the flow passage are butt-fused in the axial direction to form an integral valve box 10. However, since the spherical valve body 20 and the seat rings 40, 40 on both sides mounted in the valve box 10 are mounted without compressing the seat ring 40 with a strong force in the fully opened state, the valve box member is fully opened. 11, 12, 13 by butt fusion to each other, the seat ring 40 is not subjected to large compressive deformation,
The fusing operation is performed in a very small state. For this reason,
Compared to a conventional seat ring which is subjected to butt fusion with the same large compressive stress as at the time of valve closing, the valve box members can be butt fused without being affected by the pressing force of the seat ring 40, and the seat can be seated. During the welding operation due to the repulsive force due to the compressive stress of the ring 40, there is no such a problem that the axis between the valve box members is deformed or the dimension between the valve box members is elongated,
Accurate butt fusion can be performed.

[0014]

As described above, the synthetic resin ball valve of the present invention prevents the creep phenomenon of the seat ring when the valve is fully opened, and foreign matter in the fluid gets caught in the sealing surface between the valve body and the seat ring. As a result, it is possible to prevent the sealing performance when the valve is closed from being impaired, and to obtain a good sealing performance over a long period of time. Also, when the valve body is formed, a large compression deformation is not applied to the seat ring even in a large-diameter product in which a plurality of valve body members divided in the flow direction are butt-fused to each other to form an integrated valve body. Conventional defects such as deformation of the axis between valve box members and expansion of valve box members during fusion work due to repulsive force due to the compressive stress of the seat ring because fusion work can be performed in the state , And accurate fusion molding can be performed.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a ball valve according to an embodiment of the present invention when the valve is fully opened.

FIG. 2 is a vertical cross-sectional view of the ball valve of FIG. 1 when the valve element is closed.

FIG. 3 is a partial sectional view showing a relationship between a valve body and a seat ring when the valve of FIG. 1 is fully opened.

FIG. 4 is a partial cross-sectional view showing a relationship between a valve body and a seat ring when the valve of FIG. 1 is fully opened.

FIG. 5 is a partial cross-sectional view showing a relationship between a valve body and a seat ring when the valve of FIG. 1 is fully opened.

FIG. 6 is a sectional view of a main part of a ball valve showing a conventional technique.

FIG. 7 is a sectional view showing a main part of another conventional technique.

FIG. 8 is a sectional view showing a main part of another related art.

[Explanation of symbols]

REFERENCE SIGNS LIST 10 valve box 11 valve box central member 12, 13 valve box connecting member 14, 15 flow path 16 seat mounting groove 20 spherical valve element 21 through hole 22 spherical outer surface 23 engagement hole with valve rod 24 annular concave groove 30 valve rod 31 Handle 40 Seat ring 41 Reinforcement ring 43 Seal part 44 Seat ring crushing allowance

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasushi Kondo 200, Komukai Asahi-machi, Mie-gun, Mie Prefecture Inside Hitachi Valve Co., Ltd. (72) Inventor Takahiro Tanaka 4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka No. Osaka Gas Co., Ltd. (72) Inventor Masahiro Yamada 4-1-2 Hirano-cho, Chuo-ku, Osaka City, Osaka Prefecture Osaka Gas Co., Ltd.

Claims (4)

[Claims] 1. A spherical valve body having a through hole and a spherical outer surface, a seat ring disposed on both sides of the spherical valve body so as to face each other, and a thermoplastic material containing the seat ring and the spherical valve body therein. It is made of a resin valve box and a valve rod that is engaged with the upper part of the spherical valve body and protrudes to the upper part of the valve box. The spherical valve element is rotated via the valve rod to flow through the flow path in the valve box. In the ball valve that opens and closes, when the valve is closed, a spherical valve body and a seat ring are provided so that the spherical outer surface of the spherical valve body presses and seals the seat rings on both sides, and both ends of the spherical valve body on the through hole side. An annular groove is provided in the spherical outer surface of the portion, and the annular groove accommodates a seal portion of a seat ring when the valve is fully opened. 2. When the valve is fully opened, both ends of the spherical outer surface project toward the inner peripheral side of the seat ring, and an annular concave groove for accommodating a seal portion of the seat ring is provided on the spherical outer surface. The synthetic resin ball valve according to claim 1, wherein: 3. When the valve is fully opened, the annular groove accommodates a seal portion of the seat ring, and the pressing force of the seat ring when the valve is closed is reduced by opening the seat ring in the annular groove. The synthetic resin ball valve according to claim 1 or 2, wherein: 4. The synthetic resin ball valve according to claim 1, wherein when the valve is fully opened, the annular groove is housed with a slight gap formed between the annular groove and the seal portion of the seat ring.