JP2002257245A - Seat structure for ball valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seat structure capable of limiting moving amount of a ball, even if fluid pressure acts on the ball, and preventing abnormal rise of torque and generation of operation defects and having superior sealing property, even if the ball valve is of a floating type. SOLUTION: In this ball valve, in which the ball 14 is incorporated rotatably into a valve casing 12 provided with fluid passages 11 and 11 on both sides, valve seat structures 16 in sliding contact with the ball 14 are provided at positions on both sides sandwiching the balls 14 within the valve casing 12 and the communication of both the fluid passages 11 and 11 is opened/closed by the turning operation of the ball 14, the valve seat structure 16 is constituted by an integral structure of a soft seat 17, in sliding contact with the ball 14 and a core 18 formed, by using a material softer than that of the ball 14, and the core 18 is used also as a stopper of the ball 14, when the soft sheet 17 receives compression by the ball 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention relates to a seat structure for sealing between the ball and either side fluid passage in the ball valve.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a basic structure of a ball valve. A ball (valve element) 3 is rotatably incorporated in a valve box 2 provided with fluid passages 1, 1 on both sides. from the outside to the second upper stem 4 for rotating the ball 3 is provided,
A rubber valve seat 5 with which the ball 3 slides in order to seal between the ball 3 and both side fluid passages 1 and 1 at the ends of the fluid passages 1 and 1 on both sides of the ball 3 in the valve box 2.
And the communication between the two fluid passages 1 and 1 is opened and closed by rotating the ball 3 with the stem 4 from the outside of the valve box 2.

[0003]

[SUMMARY OF THE INVENTION Incidentally, ball valves, when the ball 3 in a closed position, the pressure of the fluid acting on the ball 3 is ready push piece, the ball valve of the floating structure shown in FIG. 3 , when used in high pressure, moves to the downstream side by the pressure of the fluid, thereby, the surface pressure of the valve seat 5 on the downstream side is increased, thereby increasing the sealing force.

As a material of the valve seat, the valve seat 5 is formed by using a hard resin such as Teflon (registered trademark) in order to prevent the valve seat 5 from being excessively compressed.

[0005] However, the use of a hard resin such as Teflon on the valve seat 5, when the dust between the sliding surfaces of the balls 3 are penetrated, the ball 3 pressed at high pressure against the valve seat 5 rotates In such a case, the valve seat 5 is damaged, and once damaged, there is a problem that the sealing property is impaired.

[0006] Here, dust resistance can be improved by using a soft sheet such as rubber for forming the valve seat 5, but the above-mentioned increase in surface pressure in the one-sided state poses a problem.

That is, in the case of the hard resin, the movement amount limited to a certain amount cannot be limited by the soft seat, the surface pressure on the downstream side abnormally increases, and the torque when the ball 3 is opened becomes abnormal. Ascends and causes malfunction.

Further, the structure of the ball valve may be a trunnion structure in which the vertical position of the ball is supported by a valve box.
Although it is a means to prevent the problem of the valve seat, the adoption of the trunnion structure increases the number of components and complicates the structure,
The production cost of the ball valve is high.

[0009] Accordingly, an object of the present invention, the fluid pressure is reduced and the amount of movement also act on the ball, abnormal increase in torque, it is possible to prevent the occurrence of operation failure, the ball valve is a floating type Another object of the present invention is to provide a seat structure of a ball valve having excellent sealing properties.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a case in which a ball is rotatably incorporated in a valve box having fluid passages on both sides, and the ball is sandwiched between both sides of the valve box. A valve seat structure in which a ball is slidably provided at a position of an end portion of the fluid passage, wherein the communication between the two fluid passages is opened and closed by a rotation operation of the ball from outside the valve box. The structure consists of an integrated structure of a soft sheet on which the ball slides and a core formed using a material softer than the ball, and this core also serves as a stopper for the ball when the soft sheet is compressed by the ball. going on up the one in which was adopted.

[0011] Here, the soft sheet has elasticity so as to be always in sliding contact with the ball, and the core is located on the inner peripheral side or the outer peripheral side of the soft sheet. structure or as thereby forming a gap between the soft sheet is formed by using a rubber core is formed by coating with a resin so as not to damage the ball resin alone or a metal Can be

[0012] The ball, when pressed by the pressure of the fluid, stops movement by abutting the core, since no compressed excessively soft sheet, abnormal increase of the torque,
An operation failure can be prevented, and the sealing performance of the valve seat can be maintained.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the ball valve includes a ball (valve element) 14 rotatably incorporated in a valve storage chamber 13 of a valve box 12 provided with fluid passages 11 on both sides.
A stem 15 for rotating the ball 14 from the outside is provided on the upper portion of the valve box 2 so as to rotate integrally with the ball 14.
A valve seat structure 16 with which the ball 14 slides in order to seal the space between the ball 14 and both side fluid passages 11, 11 is provided at both ends of the fluid passages 11, 11 on both sides of the inner ball 14. A floating type structure in which the communication between the two fluid passages 11 and 11 is opened and closed by rotating the ball 14 with the stem 15 from the outside of the stem 12.

The valve seat structure 16 includes a ball 14
And a core 18 formed of a material softer than the ball 14.
In the valve box 12, the fluid passages 11 on both sides are annular concave grooves 19 provided in the inner peripheral portion at the inner end opening into the valve storage chamber 13.
The core 18 also functions as a stopper for the ball 14 when the soft seat 17 is compressed by the ball 14.

The valve seat structure 16 of the first example shown in FIGS. 1 and 2 uses rubber for the soft seat 17, and the soft seat 17 slides on the inner periphery of the end facing the ball 14. The soft sheet 1 has a surface and is formed in an annular shape having elasticity that is always in sliding contact with the ball 14.
7, the end facing the ball 14 forms a gap with the ball 14 when the ball 14 is not compressing the soft seat 17 as shown in FIG. .

Although the material of the core 18 is not particularly limited, any material may be used as long as it is softer than the ball 14 and serves as a stopper for the ball 14. Specifically, the core 18 may be formed of a resin alone, for example, Teflon resin, super engineering plastic, or the like. It is excellent in low friction, can prevent an abnormal increase in torque with respect to the turning operation of the ball 14, and the soft sheet 17 is molded and integrated with the inner periphery provided with the ridge.

Further, as another example of the core 18, a Teflon resin,
A structure coated with a resin such as a super engineering plastic can be adopted.

The valve seat structure 1 of the second example shown in FIG.
6 shows a structure in which a core 18 is integrally provided on the inner peripheral side of the soft seat 17, and when the ball 14 is not compressing the soft seat 17, the end of the core 18 facing the ball 14 is connected to the ball 14. thereby forming a gap between.

The seat structure of the present invention is constructed as described above, and when the valve is opened when no fluid pressure acts on the ball 14, as shown in the figure, the soft seat 17 is applied to the ball 14 in a state where the ball is not compressed by the ball. A pressure contact is made to seal between the ball 14 and the fluid passages 11 and
The end facing the ball 14 forms a gap between itself and the ball 14.

[0021] When the closed position is rotated the ball 14, the ball 14 by the fluid pressure acting on the ball 14
Moves to the downstream side, and the soft sheet 17 on the downstream side is compressed.
4 will be in contact with the core 18 on the downstream side of the stopper, the soft sheet 1 thereby by the ball 14
7 is prevented from being over-compressed.

Therefore, it is possible to prevent the torque from being abnormally increased with respect to the turning operation when the ball 14 is brought to the valve-opening position. Since the soft seat 17 is always in sliding contact with the ball 14, the sealing property and the dust resistance are improved. And the ball 14 is not easily damaged.

[0023]

As described above, according to the present invention, the valve seat structure of the ball valve has an integral structure of a soft seat to which the ball slides and a core formed by using a material softer than the ball. When the ball is subjected to fluid pressure, the core acts as a stopper to suppress the movement of the ball when the soft seat receives compression, so that the soft seat prevents excessive compression. It is possible to prevent the valve seat from being received, suppress an abnormal increase in torque with respect to the rotation operation of the ball, prevent the occurrence of operation failure, and maintain the sealing property of the valve seat.

Also, by eliminating excessive compression of the soft seat with the core, even in the case of a floating type ball valve, the sealing property between the ball and the soft seat and the dust resistance are improved, and the cost and maintenance are reduced. Can be omitted.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view showing a ball valve having a seat structure according to a first embodiment of the present invention;

Figure 2 is a longitudinal front view of an enlarged showing the seat structure of the first embodiment

FIG. 3 is an enlarged longitudinal sectional front view showing a seat structure of a second example.

FIG. 4 is a longitudinal sectional front view showing a ball valve having a conventional seat structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Fluid passage 12 Valve box 13 Valve storage room 14 Ball 15 Stem 16 Valve seat structure 17 Soft seat 18 Core 19 Annular concave groove

Claims (3)

[The claims] 1. A valve seat structure in which a ball is rotatably incorporated in a valve box provided with a fluid passage on both sides thereof, and the ball slides at an end of the fluid passage on both sides of the ball in the valve box, used in sheet structure of the ball valve so as to open and close the communication of both fluid passages in the rotational operation of the ball from the valve body outside the valve seat structure, a soft sheet ball sliding contact, the soft material than the ball consists integral structure of the core formed Te, sheet structure of the ball valve soft seat the core of the ball is equal to or adapted to serve as the stopper of the ball when subjected to compression. 2. The soft sheet has elasticity so as to be always in sliding contact with the ball, and the core is located on the inner peripheral side or the outer peripheral side of the soft sheet. 2. The ball valve seat structure according to claim 1, wherein a gap is formed between the seats. 3. The soft sheet according to claim 1, wherein the soft sheet is formed using rubber, and the core is formed by coating a resin alone or a resin with a metal so as not to damage the ball. Ball valve seat structure.