JPH0755026A - Ball valve - Google Patents

Abstract

PURPOSE:To provide a ball valve maintaining sealing performance without damaging a sheet surface of a seat ring and also applicable to high pressure fluid. CONSTITUTION:A seat ring 9 consisting of an elastic body of rubber and others and an outer ring 10 made of a material of low friction coefficient of ethylene tetrafluoride resin and others are installed on a ring groove 7 provided on a body 1 and a body cap 2, a hollow space 11 is formed between a bottom part of the ring groove 7 and the seat ring 9 and a clearance with a ball 4 in the moving direction of the ball 4 is formed so that it sequentially becomes larger between the seat rings 9, between the outer rings 10 and between valve seat parts 1a, 2a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a floating ball type ball valve.

[0002]

2. Description of the Related Art FIG. 6 is a vertical cross-sectional view showing an example of a conventional floating ball type ball valve used for a relatively low pressure. Reference numeral 21 is a ball valve, 22 is a body, 23 is a body cap, and 24 is a body cap. Seat ring, 25
Is a ball having a through hole, 26 is a stem, and 27 is a handle. The handle 27 rotates the ball 25 via the stem 26 to open and close the ball valve 21.
A seat ring 24 is provided between the body 22 and the ball 25 and between the body cap 23 and the ball 25, and the ball 25 pressed by the fluid pressure in the valve closed state causes the downstream seat ring 24 to move to the body 22 or the body cap 2.
Press between 3 and seal.

FIG. 7 is a longitudinal sectional view showing an example of a conventional floating ball type ball valve used for a relatively high pressure, where 31 is a ball valve, 32 is a body,
33 is a body cap, 34 is a seat ring, 35 is a ball having a through hole, 36 is a stem, 37 is a handle, 38 is a seat retainer for mounting the seat ring 34, and 39 is a disc spring. The ball 35 is rotated by the handle 37 via the stem 36 to move the ball valve 3
Open and close 1. Seat ring 34 is seat retainer 3
The ball 35, which is mounted on the valve 8 and is pressed by the disc spring 39 and pressed by the fluid pressure in the valve closed state, presses and seals the downstream seat ring 34 with the seat retainer 38, and also the upstream side. Also in the above, the upstream side pressure seal of the O-ring, which is larger in diameter than the seat ring 34, also presses and seals the seat ring 34 against the ball on the upstream side.

[0004]

In FIGS. 6 and 7, the seat rings 24 and 34 are generally made of tetrafluoroethylene resin having a high strength and a low frictional resistance. When flushing after construction,
Alternatively, foreign matter such as rust and sand during use may cause seat ring 2
The sheet surface of 4 or 34 is damaged or adheres to the sheet surface, and the sealing performance is deteriorated at an early stage. To avoid this, a soft elastic material such as rubber may be used for the seat ring, but this seat ring has a large frictional resistance with the ball and is used for opening and closing the ball valve by rotating the ball. Requires a large amount of operating force.

Further, as conventional floating ball type ball valves, there are JP-A-52-8230 and JP-A-52-8231. These are related to ball valve seats in which a low friction material such as nylon and a rubber material are combined, and a rubber material is used for the contact surface with the spherical valve body. The seal ring made of rubber may be deformed in the direction of the inner diameter and may be damaged.In the latter case, when used under high pressure, an annular ring or presser ring made of tetrafluoroethylene resin equipped with a rubber seal ring may be used. Damaged,
In addition, the cushion ring made of a rubber material has a defect such as being damaged, and any of the examples can be said to be a sealing mechanism that is compatible only with a low pressure fluid.

The present invention has been developed in view of the above-mentioned conventional problems, and an object thereof is to be able to continuously maintain the sealing performance without damaging the seat surface of the seat ring. Another object of the present invention is to provide a ball valve seal mechanism applicable to high-pressure fluid.

[0007]

In order to achieve the above object, the present invention provides a ball valve in which a ball having a through hole provided inside a valve box is rotatably provided by operating a stem. A seat ring with a substantially rectangular cross-section that seals the spherical surface of the ball is formed with an elastic body such as rubber,
This seat ring is mounted in an annular groove provided in the vicinity of the ball spherical surface in the valve box, the inner peripheral portion of this annular groove serves as a valve seat portion, and the tetrafluoroethylene having a lip portion on the outside of this seat ring. An outer ring made of a material with a low coefficient of friction such as resin is provided, and the bottom of the seat ring and the bottom of the annular groove are formed so as to incline toward the ball toward the inner diameter. When it is located at the center of the seat ring, an annular space for pressing and deforming the seat ring by the ball is provided between the bottom surface of the seat ring and the bottom of the annular groove, and the ball and the valve seat part The gaps in the moving direction of the balls between the seat ring, the outer ring, and the valve seat are increased in this order.

In this case, it is preferable that the above-mentioned vacant chamber is formed such that the gap between the bottom surface of the seat ring and the bottom portion of the annular groove becomes larger toward the outer diameter. It is preferable to form at least one radial communicating portion at a circumferential position facing the rear end portion of the seat ring of the outer ring.

Further, an angle formed by the annular groove of the bottom portion of the annular groove facing the seat ring and the inner diameter surface is substantially the same as an angle formed by the side surface on the rear end side of the seat ring with the inner peripheral surface, An annular recess having a substantially arcuate cross section may be formed in the middle of the side surface on the rear end side of the seat ring.

[0010]

Since the present invention is configured as described above, in the valve closed state, the ball pressed by the fluid pressure first presses the seat ring on the downstream side to form an annular space between the ball and the bottom of the annular groove. It deforms while making the chamber smaller and comes into contact with the outer ring. When the pressing force of the ball pressed by the fluid pressure is stronger, the lip portion of the outer ring is deformed to strengthen the contact with the outer ring and to deform the seat ring while further reducing the vacant space. The ball comes into contact with the valve seat only when the fluid pressure is so high that the seat ring is deformed to the maximum extent and the empty space disappears.

During this time, the vacant chamber is closed in the radial direction from the inner diameter portion where the gap is narrow. Then, the fluid in the chamber is pushed out in the outer diameter direction, passes through the communication portion formed in the outer ring, and is discharged into the body cavity. Next, after closing the valve, the upstream pressure passes through the communicating portion of the outer ring, the fluid pressure acts on the seat ring,
The seat ring has a trapezoidal shape in which the angle between the inner peripheral surface and the side surfaces on both sides is obtuse in cross section, and the inner diameter side is narrowed, so that between the inner peripheral surface of the seat ring and the inner diameter surface of the annular groove. The surface pressure is high and there is no leakage through the back of the seat ring.

Since the seat ring of the ball valve is made of an elastic material such as rubber, even if it is damaged by rust, sand or the like, or adheres thereto, the sealing property is extremely good. In addition, since the surface of the seat ring made of an elastic body such as rubber that comes into contact with the ball is narrow, the ball comes into contact with the outer ring made of a material having a low coefficient of friction when the seat ring is compressed to some extent.
For example, even if it is used in a high-pressure gas pipe, the operating torque does not increase. Moreover, when the fluid pressure becomes extremely high, the ball abuts on the valve seat portion, so that the seat ring and the outer ring are not excessively compressed and deformed. This ball valve can also be used for high-pressure gas pipes, as it also prevents it from protruding. Of course, this valve seat also becomes fire-safe when the ball abuts.

[0013]

Embodiments of the floating ball type ball valve according to the present invention will be described below in detail with reference to FIGS. 1 is a vertical cross-sectional view showing an example of a case where the ball is in the center position in a pressure equalizing state, FIG. 2 is a partially enlarged cross-sectional view showing a case where the valve of FIG. 1 is in a closed state, and FIG. FIG. 4 is a partially enlarged cross-sectional view showing a state in which pressure acts in the direction of the arrow in FIG. 3 and only the right side sealing mechanism seals. In the drawing, a ball 4 having a through hole 4a is incorporated in a valve box 3 composed of a body 1 and a body cap 2,
The stem 5 opens and closes the ball 4. In addition, the ball 4 and the stem 5 are joined to each other by providing the groove 4b on the ball 4 and the convex portion 5a on the stem, and joining the concave groove 4b and the convex portion 5a to rotate the ball 4 Open and close the valve. The convex portion 5a of the stem 5 and the concave groove 4 of the ball 4
As shown in FIG. 2, when the ball 4 is in the valve closed state, the joint portion b is incorporated into the stem 5 such that the ball 4 is movable in the left-right direction by a predetermined distance. The operation of the stem 5 is, for example, as shown in FIG. 1, a manual type using a lever handle 6 or another appropriate operating device is used.

A seal mechanism S for sealing a fluid is attached to both sides of the ball 4, and the seal mechanism S has a valve seat portion 1a or 2a of the body 1 or body cap 2 and an annular groove. 7 and an annular outer peripheral groove 8 provided at the outer peripheral position of the groove 7, a seat ring 9 is attached to the annular groove 7, and an outer ring 10 is attached to the outer peripheral groove 8.

The seat ring 9 is made of an elastic material such as rubber and has a substantially rectangular cross section. The spherical surface 4c of the ball 4 and the contact surface 9a of the seat ring 9 are tangent to the contacting spherical surface 4c. Approximately parallel, spherical surface 4 with contact surface 9a
The distance from c is H1 at the minimum. Further, the bottom surface 9b of the seat ring 9 is closer to the ball 4 side toward the inside, and the outer diameter surface 9c and the inner diameter surface 9d are inclined toward the ball 4 side by a height h.

In FIG. 4, the bottom portion 7a of the annular groove 7 is parallel to the stem 5 up to the position W from the outer peripheral groove 8 and is offset from the lower end portion to the inner diameter surface 7b by the height h toward the ball 4 side. A space surrounding the bottom portion 7 a of the seat 7 and the bottom surface 9 b of the seat ring 9 is defined as a vacant chamber 11. FIG. 5 is a partially enlarged cross-sectional view showing another example of the vacant chamber. In the figure, an annular recess 9e having a substantially arc-shaped cross section is formed in the middle of the bottom surface 9b of the seat ring 9, and the annular recess is formed. 9 shows an example in which the space surrounded by 9e and the bottom portion 7c of the annular groove 7 is a vacant chamber 11a.

The outer ring 10 is made of a material having a low coefficient of friction such as tetrafluoroethylene resin. The outer ring 10 has a lip portion 10a at its tip and an outer surface of the lip portion 10a which is a contact surface. Form 10b. The outer ring 10 is slidable in the outer peripheral groove 8, and the outer ring surface 9c of the seat ring 9 and a part of the front end surface thereof are provided with a lip portion 10.
Assemble to cover with a. Furthermore, the above-mentioned lip portion 10a
Is provided such that the tip end side of the ball 4 with respect to the spherical surface 4c is the narrowest in the gap H2. In addition, the outer ring 10 is provided with an appropriate number of communicating portions 10c that communicate with the vacant chamber 11 around the outer ring 10. In this case, the communication portions 10d and 10e may be provided as shown by the chain line in FIG.

The clearance between the valve seat portion 1a or 2a and the spherical surface 4c of the ball 4 is H3, which is the narrowest on the seat ring 9 side, and the spherical surface 4c of the ball 4 and the valve seat portions 1a, 2a,
The relationship between the clearances of the seat ring 9 and the outer ring 10 is H1 <H2 <H3.

Next, the operation of the above embodiment will be described. When the ball 4 is closed when the fluid is flowing from the left side to the right side as shown by the arrow in FIG. 3, the ball 4 is pressed against the seal mechanism S as shown in FIG. Seal. That is, the spherical surface 4c of the ball 4 first contacts the contact surface 9a of the seat ring 9, and then the outer ring 1
The lip portion 10a of 0 is pressed against the valve seat portion 2a by pressing. In this case, the volume of the vacant chamber 11 is filled with H3-H1 minutes of the seat ring 9, and H3-H2 minutes which is the difference between the valve seat portion 2a and the lip portion 10a is equal to the lip portion 1.
The outer ring 10 is compressed and absorbed when the outer ring 10 bends. At that time, the inner diameter surface 10f of the outer ring 10 moves to the inner diameter side, the outer diameter surface 9c of the seat ring 9 is compressed to the inner diameter side, and the inner diameter surface 9d and the bottom surface 9b of the seat ring 9 are fixed to the inner diameter portion 7b of the annular groove 7. And the bottom 7a.

Further, the fluid passes through the communicating portion 10c from the fitting portion of the outer diameter portion 8a of the outer peripheral groove 8 and the outer diameter surface 10g of the outer ring 10 to compress the seat ring 9 inward, The height of the ring 9 is the contact surface 9a and the bottom surface 9b.
Since the inner diameter side is small due to the inclination of, the inner diameter portion 9d
And, the crimping to the inner diameter portion 7b becomes stronger, and this portion is more reliably sealed.

In FIG. 3, on the left side, that is, on the upstream side, fluid flows from H3, H1 and H2 which are gaps between the spherical surface 4a of the ball 4 and the valve seat portion 1a, the seat ring 9 and the outer ring 10 and is not sealed. . If the valve is closed, the height X of the seat ring 9 increases by H2 (H2 + H2 = 2H2 if the ball moves), and the vacant chamber 11 becomes large. As a result, the contact between the inner diameter portion 7b of the annular groove 7 and the inner diameter surface 9d is weakened, and the fluid is vacant in the chamber 11 and the communicating portion 10d.
After passing through, this part will not be sealed. The shapes of the valve seat portions 1a, 2a, the contact surface 9a of the seat ring 9 and the contact surface 10b of the outer ring 10 are not limited to those in the above-described embodiment, and may have the same curvature as the spherical surface 4a of the ball 4, for example. It may be any other shape.

Since the seat ring 9 on the side of the body 1 and the body cap 2 is made of an elastic material such as rubber, even if the seat ring 9 is damaged by rust, sand or the like or adheres thereto, the sealing property is very good. Further, the seat ring 9 formed of an elastic material such as rubber has a narrow surface for contacting the ball 4, and when the seat ring 9 is compressed to a certain extent, the ball 4 becomes an outer ring 10 formed of a material having a low friction coefficient. Since they come into contact with each other, the operating torque does not become so high even when used in, for example, a high-pressure gas pipe. Moreover, when the fluid pressure becomes extremely high, the ball 4 moves toward the valve seat portions 1a, 2
Since it abuts on a, the seat ring 9 and the outer ring 10 are not excessively compressed and deformed.

[0023]

As is apparent from the above, according to the present invention, the sealing property is assured without the rust, sand or the like damaging the seat surface of the seat ring or attaching them. The seat ring made of the elastic material is not excessively compressed or deformed, or the seat ring is prevented from protruding so that the seat ring is not deteriorated or damaged. Moreover, since the area of the seat ring that comes into contact with the balls is small, the seat ring is provided with an empty space for deformation, and the seat surface pressure does not become excessive. Therefore, the operating torque does not become excessive, and therefore, It is possible to provide a ball valve having excellent sealability, operability, durability and reliability.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an embodiment in which a ball valve according to the present invention is in a pressure equalized state and a ball is at a center position.

FIG. 2 is a partially enlarged sectional view showing a case where the valve of FIG. 1 is in a closed state.

FIG. 3 is a partially enlarged cross-sectional view showing a state in which only the downstream side seal mechanism seals due to the fluid pressure in FIG.

FIG. 4 is an enlarged sectional view of a valve seat portion of FIG.

FIG. 5 is a partially enlarged sectional view showing a part of a valve seat portion of another embodiment of the ball valve of the present invention.

FIG. 6 is a vertical sectional view showing an example of a conventional floating ball valve for low pressure.

FIG. 7 is a longitudinal sectional view showing an example of a conventional floating ball valve for high pressure.

[Explanation of symbols]

 1 Body 1a, 2a Valve Seat 2 Body Cap 3 Valve Box 4 Ball 4a Through Hole 4b Concave Groove 4c Spherical Surface 5 Stem 5a Convex 6 Lever Handle 7 Annular Groove 7a Bottom 8 Outer Groove 9 Seat Ring 9a Contact Surface 9b Bottom 10 Outer Ring 10a Lip 11 Vacancy S Seal mechanism

Claims (4)

[Claims] 1. A ball valve in which a ball having a through hole provided inside a valve box is rotatably provided by operating a stem, and a rubber seat ring having a substantially rectangular cross section for sealingly contacting the spherical surface of the ball. Made of an elastic material such as
This seat ring is mounted in an annular groove provided in the vicinity of the ball spherical surface in the valve box, the inner peripheral portion of this annular groove serves as a valve seat portion, and the tetrafluoroethylene having a lip portion on the outside of this seat ring. An outer ring made of a material with a low coefficient of friction such as resin is provided, and the bottom of the seat ring and the bottom of the annular groove are formed so as to incline toward the ball toward the inner diameter. When it is located at the center of the seat ring, an annular space for pressing and deforming the seat ring by the ball is provided between the bottom surface of the seat ring and the bottom of the annular groove, and the ball and the valve seat part A ball valve characterized in that a gap in the moving direction of the ball between the seat ring, the outer ring, and the valve seat is increased in this order. 2. The ball valve according to claim 1, wherein the gap between the bottom surface of the seat ring and the bottom portion of the annular groove becomes larger toward the outer diameter. 3. The angle formed by the bottom surface of the annular groove facing the seat ring with the inner diameter surface of the annular groove is substantially the same as the angle formed by the side surface on the rear end side of the seat ring with the inner peripheral surface, 2. The ball valve according to claim 1, wherein an annular recess having a substantially arcuate cross section is formed in an intermediate portion of the side surface on the rear end side of the seat ring. 4. The ball valve according to claim 1, wherein at least one radial communicating portion is formed at a circumferential position facing the rear end portion of the seat ring of the outer ring.