JP2003240133A - Ball valve and fluid supply system using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the uneven abrasion of a ball seat and the rise of valve operating torque, and also to prevent the sticking of a seat mechanism caused by accumulation of powder. <P>SOLUTION: This ball valve comprises: a ball 14 rotatably supported by a pair of stems 15a, 15b on a channel 13 formed in a housing 12, for opening and closing the channel 13 by a through hole 14a communicated to the channel 13; an annular ball seat 17 mounted at a primary side of the ball 13 and closely abutted on an outer peripheral face of the ball 14; a seat retainer 20 for holding the ball seat 17; an O-ring 18 having a seal diameter Do larger than a seal diameter Ds of the ball seat 17, and mounted on a position farthermost from the ball 14 for sealing between the housing 12 and the seat retainer 20; and an O-ring 19 having a seal diameter Di larger than the seal diameter Do of the O-ring 18, and mounted on a position closest to a ball 14 side for sealing between the housing 12 and the seat retainer 20. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ball valve and a fluid supply system using the same, and particularly to a technique effectively applied to prevent uneven wear of a ball seat used for a ball valve and to prevent sticking of a seat mechanism. It is about.

[0002]

2. Description of the Related Art Various valves are used in pipes through which a fluid such as liquid or gas flows so as to control the flow of the fluid. When automatically controlling the valve, a 90-degree opening / closing type ball valve is suitable from the viewpoint of operability and cost.

Now, a conventional ball valve will be described.

FIG. 8 is a cross-sectional view of essential parts showing an example of a seat mechanism in a conventional ball valve.

In the ball valve shown in FIG. 8, a ball 114 having a through hole (not shown) is rotatably arranged on a flow path 113 formed in a housing 112, and the ball 114 is rotated. The flow path 113 is opened and closed by connecting or blocking the through hole and the flow path 113, and an annular ball seat 117 is provided that is in pressure contact with the outer peripheral surface of the ball 114. And the ball seat 11
The annular seat retainer 120 that holds 7 is urged toward the ball 114 side by the spring 121,
It is arranged so that it can be displaced in the axial direction.

An annular groove 1 is formed on the outer periphery of the seat retainer 120.
20a is formed, and an O-ring 128 that seals between the seat retainer 120 and the housing 112 is attached to the annular groove 120a.

[0007]

In the ball valve having such a structure, the ball seat 117 is opened at the valve intermediate opening degree.
The sealing surface of is not always in contact with the ball 114, but there is a surface that is always in contact with the ball 114 and a surface that is in contact only when fully opened or fully closed. That is, at the valve intermediate resolution, the ball seat 117 hits the ball 114 one-sided. Particularly, in the case of a ball valve having a trunnion structure in which the ball 114 is supported by a pair of stems, the ball seat 117
However, when the ball valve repeatedly opens and closes, uneven wear of the ball seat 117 due to uneven contact with the ball 114 is likely to occur. Further, the ball seat 117 is always the ball 11
Since it is pressed by 4, the torque required to operate the valve exceeds the frictional force between the ball 114 and the ball seat 117.

Here, in a ball valve that handles powder as a fluid, there is a problem that the powder enters and accumulates between the housing and the seat mechanism, and the seat mechanism is fixed and the sealing performance is impaired.

In order to solve this problem, for example, the techniques described in Japanese Patent No. 2678876 and Utility Model Registration No. 3050961 have been proposed.

Here, Japanese Patent No. 2678876 discloses a technique of disposing a dust seal at an end portion of a seat retainer to prevent powder from entering between the housing and the seat mechanism. In addition, utility model registration No. 3050961
JP-A No. 2003-242242 discloses a technique of taking in pressure between a housing and a seat mechanism and blowing out invading powder.

However, in the above-mentioned technique, the fluid (gas body) after the powder removal enters between the housing and the seat mechanism, so that the fluid that enters is powdered and deposited by a chemical reaction. Can't be stopped.

Therefore, an object of the present invention is to provide a ball valve capable of preventing uneven wear of the ball seat and reducing valve operating torque.

It is another object of the present invention to provide a ball valve which can prevent the seat mechanism from being fixed due to the accumulation of powder between the housing and the seat mechanism.

[0014]

In order to solve the above-mentioned problems, a ball valve according to the present invention is rotatably arranged on a flow channel formed in a housing and supported by a pair of stems. A ball having a through hole communicating with the ball for opening and closing a flow path by the through hole; an annular ball seat provided on the primary side of the ball and pressed against the outer peripheral surface of the ball; and a holding member for holding the ball seat. A first seal means having a seal diameter larger than the seal diameter of the ball seat and arranged at a position farthest from the ball and sealing between the housing and the holding member; and a seal diameter of the first seal means. And a second sealing means which has a larger seal diameter and is arranged on the most ball side, and which seals between the housing and the holding member.

According to such an invention, at the valve intermediate opening degree, a fluid pressure causes a force to separate the ball seat from the ball, and sliding between the balls is lost. Therefore, uneven wear of the ball seat is prevented. And, it becomes possible to reduce the valve operating torque.

Further, the first and second sealing means are mounted between the holding member and the housing, and each time the ball seat comes into contact with or separates from the ball, the holding member itself moves back and forth in the axial direction of the flow path. Since it slides against the ground, it prevents powder from entering and accumulating between the housing and the seat mechanism even when a powder fluid is used, and it also accumulates on the sliding part between the housing and the seat mechanism. By doing so, it becomes possible to prevent the seat mechanism from sticking.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described more specifically with reference to the drawings. Here, in the accompanying drawings, the same reference numerals are given to the same members,
Moreover, the duplicate description is omitted. It should be noted that the embodiment of the present invention is a particularly useful embodiment for carrying out the present invention, and the present invention is not limited to the embodiment.

FIG. 1 is a sectional view showing a ball valve according to one embodiment of the present invention, FIG. 2 is a schematic view showing a fluid supply system using the ball valve of FIG. 1, and FIG. 3 is a view showing the ball valve of FIG. FIG. 4 is a cross-sectional view of a main part showing a first operation state, FIG. 4 is a cross-sectional view of a main part showing a second operation state of the ball valve of FIG. 1, and FIG. 5 is a cross-sectional view showing a third operation state of the ball valve of FIG. 7 is a partial sectional view, FIG. 6 is a partial sectional view showing a fourth operating state of the ball valve of FIG.
FIG. 4 is a graph showing fluctuations in the primary side fluid pressure and the secondary side fluid pressure when the ball valve of FIG. 1 transitions from the third operating state to the fourth operating state.

The ball valve 1 of the present embodiment shown in FIG.
1, the housing 12 is composed of a body 12a and a body cap 12b, and has a side entry type structure in which a cylindrical flow path 13 is formed. However, other structures such as a top entry type may be used.

Inside the housing 12, a ball 14 having a cylindrical through hole 14a communicating with the flow path 13 is arranged on the flow path 13. This ball 14 is the flow path 1
A pair of stems 15a, 1 arranged in a direction orthogonal to 3
It is supported by 5b and is rotatably mounted in the direction in which the flow path 13 is opened and closed by the through hole 14a with the stems 15a and 15b as pivot points. Here, the ball 14 is made of metal or resin, and when made of metal, for example, stainless steel, carbon steel, ductile, cast iron, bronze, brass, etc., and when made of resin, for example, fluororesin or nylon. Resin or the like is used.

Primary side of ball 14 (side into which fluid flows)
An annular ball seat 17 that is pressed against the outer peripheral surface of the ball 14 is provided in the. This ball seat 17
It is held by an annular seat retainer (holding member) 20 by a stopper 16 screwed. The seat retainer 20 is provided so as to be displaceable in the axial direction of the flow path 13,
A spring (elastic member) 21 that urges the seat retainer 20 toward the ball 14 by elastic force is provided on the side of the seat retainer 20 opposite to the ball 14. Therefore, the ball 14 rotates while sliding on the ball seat 17.

A first annular groove 20a and a second annular groove 20b are formed on the outer periphery of the seat retainer 20,
The first annular groove 20 located on the side away from the ball 14.
An O-ring (first sealing means) 18 is attached to the ball 1
In the second annular groove 20b located on the fourth side, the O-ring (second
(Seal means) 19 are attached respectively. The seal diameter Do of the O-ring 18 (seal diameter between the O-ring 18 and the housing 12) mounted in the first annular groove 20a on the side separated from the ball 14 is the seal diameter of the ball seat 17 (ball seat 17 The seal diameter is larger than the seal diameter with the ball 14) Ds.
The seal diameter Di (seal diameter between the O-ring 19 and the housing 12) Di of the O-ring 19 mounted in the second annular groove 20b on the fourth side is larger than the seal diameter Do of the O-ring 18 ( Ds <Do <Di).

As described above, the ball seat 17 is provided between the ball 14 and the seat retainer 20, and the seat retainer 2 is provided.
The O and the housing 12 are sealed by O-rings 18 and 19, respectively. The sliding range of such a seat mechanism is, for example, 2 to 6 mm.

The ball seat 17 is made of resin such as fluororesin or rubber such as synthetic rubber, but may be made of metal.

Further, in the present embodiment, the coil spring is used as the spring 21 because it can cope with a large displacement and the change of the pressing load is small.
A leaf spring or disc spring may be used.

Further, in this embodiment, the O-ring 1 is inserted into the annular grooves 20a and 20b formed in the seat retainer 20.
Although 8 and 19 are attached, an O-ring 18 and 19 may be attached by forming an annular groove on the housing 12 side.

Further, in the present embodiment, the ball seat 1
Although the sheet retainer 7 and the sheet retainer 20 holding the sheet 7 are separate bodies, they may be integrally formed with each other.

In the illustrated ball valve 11, no seal mechanism is provided on the secondary side (the side on which the fluid flows out). Therefore, the periphery of the stems 15a and 15b communicates with the secondary side, and the secondary side pressure P ₂ acts.

Ball valve 11 having such a structure
Is used in a fluid supply system as shown in FIG. 2, for example. That is, in FIG. 2, the ball valve 11 is installed on the pipe 30 through which a predetermined fluid (for example, powder fluid) flows. Further, on the pipe 30 on the downstream side of the ball valve 11, an open / close valve 31 that opens and closes the flow path of the pipe 30 is installed. Further, between the ball valve 11 and the opening / closing valve 31, a processing unit 32 for attaching a predetermined process (for example, heat treatment, pressure treatment, reaction treatment with another substance) to the fluid is attached.

Although various valves such as a ball valve and a butterfly valve can be applied to the opening / closing valve 31, the ball valve 11 shown in FIG. It is suitable.

Next, the operation of the ball valve and the fluid supply system having the above construction will be described.

[0032] In the fluid supply system shown in FIG. 2, the first operating state in which the ball valve 11 with no load becomes the flow path open position (FIG. 3), the ball seat 17 by the pressing force F _a of the spring 21 the ball 14 is pressed. Since the first operating state is no load, no fluid pressure acts on the O-rings 18 and 19. In the first operation state, the valve position of the opening / closing valve 31 may be the flow path open position or the flow path closed position.

Next, set the ball valve 11 to the flow path open position,
Set the on-off valve 31 to the flow path closed position, that is, the load, that is, the valve primary
In the second operating state (Fig. 4), where fluid is supplied from the side,
Since the valve 11 is at the flow path opening position,
Fluid pressure P₁ And secondary side fluid pressure P_Two Is the same as (P₁ = P
_Two )become. Then, the O-ring 18 and the O-ring 19
Due to the difference in fluid pressure acting on the area of the seal diameter,
Displace the ball 20 in the direction away from the ball 14.
Force, that is, the force F that separates the ball seat 17 from the ball 14
_b Occurs. Where F_b = [(Di^Two -Do
^Two ) Π / 4] × [P ₁ = P_Two ]. And Bo
Force F for separating the seat 17 from the ball 14_bSpline
Pressing force F of G21_a , And as shown in Fig. 4,
Sheet 17 (F_b -F_a ) To retreat
Separate from the ball 14.

When the ball 14 is rotated from the second operating state to the third operating state (FIG. 5) where the ball 14 is turned to the flow passage closed position where the through hole 14a does not communicate with the flow passage 13, the ball seat 17 is moved. Remains separated from the ball 14. Then, at the time of transition from the second operating state to the third operating state, the ball 14 is rotated to the closed position without contacting the ball seat 17, so that the ball valve 11 is operated from the open position to the closed position. At the intermediate opening degree, the ball 14 and the ball seat 17 no longer slide, and the ball seat 1
The uneven wear of No. 7 and the valve operating torque can be reduced.

In the fourth operating state (FIG. 6) in which the opening / closing valve 31 is set to the flow path opening position from the third operating state, the secondary side fluid pressure P ₂ decreases and the primary side fluid pressure P ₁ and the secondary side fluid pressure P ₂ decrease. Fluid pressure P ₂
Since (P ₁ > P ₂ ), the force F _{b for} separating the ball seat 17 from the ball 14 becomes small, and when this force F _b becomes less than the pressing force F _a of the spring 21,
The ball seat 17 moves forward and is pressed by the ball 14, and the valve seat seal functions. Further, since the fluid is always supplied to the primary side, the ball seat 17 is seated on the ball seat 17 by the difference in the fluid pressure acting on the seal diameter area of the O ring 18 and the O ring 19 from the moment the valve seat seal functions. Retainer 2
0 a force to displace in the direction of the ball 14, i.e. a force F _c that presses the ball seat 17 the ball 14 is generated.

Therefore, as shown in FIG. 6, from the moment when the valve seat seal functions, the ball seat 17 becomes (F _a +
The ball 14 is pressed by the load F _c −F _b ). Here, F _b = [(Di ² −Ds ² ) π /
4] × P ₂ and F _c = [(Do ² −Ds ² ) π.
/ 4] × P ₁ .

Further, when the ball valve 11 is operated to the flow path opening position and the opening / closing valve 31 is operated to the flow path closing position from the fourth operation state, the ball 14 is moved to the ball seat 1.
The rotation starts while being pressed by 7. Then, when the through hole 14a and the flow path 13 start to communicate with each other, the secondary side fluid pressure P ₂
Gradually increases, and the secondary side fluid pressure P ₂ shifts to a state (P ₁ = P ₂ ) in which the secondary side fluid pressure P ₂ is balanced with the primary side fluid pressure P ₁ . Accordingly, when the value exceeds the force _{F c} that presses the pressing force _{F a} and the ball sheet 17 of the spring 21 the ball sheet 17 becomes gradually larger force _{F b} away from the ball 14 in the ball _{14 [F b> (F a} + F c )],
The ball seat 17 retracts from the ball 14 and the valve seat seal is released.

Therefore, although the ball 14 and the ball seat 17 are in contact with each other immediately after the start of the operation, F _b > (F _a
The ball 14 is rotated to the open position without contacting the ball seat 17 when + F _c ). As a result, sliding of the ball 14 and the ball seat 17 is prevented even at an intermediate opening for operating the ball valve 11 from the closed position to the open position, and uneven wear of the ball seat 17 is prevented and valve operating torque is reduced. You can

[0039] Then, from the moment the valve seat seal is released, the force _{F b} separating the ball seat 17 from the ball ^{_{14 F b = [(Di 2}} -Do 2) π / 4] × [P 1 = P
₂ ], the ball seat 17 is separated from the ball 14 by the force of (F _b −F _a ) in the second operation state described above.

Here, the primary side fluid pressure P when the ball valve 11 shifts from the third operating state to the fourth operating state.
₁ and the variation of the secondary side fluid pressure P ₂ shown in FIG. A ball valve made of class 300 stainless steel (size: 6B) was used for the evaluation. Moreover, the fluid pressure of 3.0 MPa was always supplied to the primary side of the valve.

In FIG. 7, before the point A which is the third operating state, the primary side fluid pressure P ₁ and the secondary side fluid pressure P ₂
Are the same at a supply pressure of 3.0 MPa.

From this state, when the opening / closing valve 31 is set to the flow path opening position and the secondary side of the ball valve is opened (point A), the valve internal pressure starts to rapidly drop on both the primary side and the secondary side. Then, when the valve internal pressure drops to about 0.7 MPa, the ball seat 17 presses the ball 14 and the valve seat seal functions (point B). Then, after the point B, the primary side fluid pressure P
₁ returns to the supply pressure of 3.0 MPa,
The secondary fluid pressure P ₂ drops to 0 MPa. It is noted that point B is a balance point at which the ball seat 17 comes into contact with and separates from the ball 14, and is about 0.7 MPa in the sample ball valve.

From the above, the ball seat 17 is separated from the ball 14 in the same pressure state on the primary side and the secondary side, and when the valve internal pressure falls below the balance point at the valve closed position, the ball seat 17 is pressed against the ball 14. It was confirmed that the valve seat seal worked.

[0044] Thus, according to this embodiment, the sliding of the force F _b separating the ball seat 17 from the ball 14 by the fluid pressure is generated in the valve intermediate opening ball 14 and ball seat 17 Ball seat 17
Uneven wear can be prevented and the valve operating torque can be reduced.

Further, the seat retainer 20 and the housing 1
O-rings 18 and 19 are mounted between the seat retainer 20 and the seat 2, and the seat retainer 20 slides back and forth in the axial direction of the flow path 13 every time the ball seat 17 comes into contact with and separates from the ball 14.
Therefore, even when powder fluid is used, the housing 12
It is possible to prevent the powder from invading and accumulating between the sheet mechanism and the sheet mechanism, and also to prevent the sheet mechanism from sticking due to the powder accumulating on the sliding portion between the housing 12 and the sheet mechanism. Become.

By installing such a ball valve 11 on the piping of the fluid supply system, it becomes possible to reliably supply a fixed amount of powder fluid.

In the present embodiment described above, the seal diameter Ds of the ball seat 17 is located between the housing 12 and the seat retainer 20 on the side separated from the balls 14.
O-ring 18 with larger seal diameter Do and ball 1
Although it is located on the fourth side and is sealed by an O-ring 19 having a seal diameter Di larger than the seal diameter Do of the O-ring 18, the housing 12 and the seat retainer 20 are provided between the O-ring 18 and the O-ring 19. One or a plurality of other sealing means may be provided to seal the gap between and. In this case, the seal diameter of the other sealing means may be larger or smaller than the seal diameters Do and Di of the O-rings 18 and 19.

Therefore, the O-ring 18 which is the first sealing means means the one which is arranged at the position farthest from the ball 14, and the O-ring 19 which is the second sealing means is arranged at the most ball 14 side. Point to something, O-ring 1
A sealing means may or may not be mounted between the 8 and the O-ring 19.

Of course, the ball valve of the present invention can be applied to a wide variety of fluids other than powder.

[0050]

As is apparent from the above description, according to the present invention, the following effects can be obtained. (1) .At the valve intermediate opening degree, fluid pressure causes a force to separate the ball seat from the ball, and sliding between the balls is lost, preventing uneven wear of the ball seat and reducing valve operating torque. It becomes possible to plan. (2). The first and second sealing means are mounted between the holding member and the housing, and the holding member itself moves forward and backward in the axial direction of the flow path every time the ball seat comes into contact with and separates from the ball. Since it slides, the powder is prevented from entering and accumulating between the housing and the seat mechanism even when a powder fluid is used, and the powder is accumulated on the sliding portion between the housing and the seat mechanism. This makes it possible to prevent the seat mechanism from sticking.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a ball valve according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a fluid supply system using the ball valve of FIG.

FIG. 3 is a cross-sectional view of main parts showing a first operating state of the ball valve of FIG.

FIG. 4 is a cross-sectional view of main parts showing a second operating state of the ball valve of FIG.

5 is a cross-sectional view of a main part showing a third operating state of the ball valve of FIG.

FIG. 6 is a cross-sectional view of a main part showing a fourth operating state of the ball valve of FIG.

FIG. 7 shows the ball valve of FIG. 1 in the third to fourth operating states.
6 is a graph showing fluctuations in the primary-side fluid pressure and the secondary-side fluid pressure when the operating state of FIG.

FIG. 8 is a cross-sectional view of essential parts showing an example of a seat mechanism in a conventional ball valve.

[Explanation of symbols]

12 housing 12a body 12b body cap 13 channels 14 balls 14a through hole 15a, 15b stem 16 stopper 17 ball seats 18 O-ring (first sealing means) 19 O-ring (second sealing means) 20 Seat retainer (holding member) 20a First annular groove 20b Second annular groove 21 Spring (elastic member) 112 housing 113 channel 114 balls 117 ball seat 120 seat retainer 120a annular groove 121 spring 128 O-ring

Claims (5)

[Claims] 1. A through hole that is supported by a pair of stems and is rotatably disposed on a flow channel formed in a housing, and that communicates with the flow channel is formed, and the flow channel is opened and closed by the through hole. A ball, an annular ball seat provided on the primary side of the ball and pressed against the outer peripheral surface of the ball, a holding member for holding the ball seat, and a seal diameter larger than the seal diameter of the ball seat. And a first seal means disposed at a position most distant from the ball and for sealing between the housing and the holding member, and a seal diameter larger than a seal diameter of the first seal means. A ball valve, which is disposed on the most ball side and has a second sealing means for sealing between the housing and the holding member. 2. The ball valve according to claim 1, further comprising an elastic member for urging the holding member toward the ball. 3. The ball valve according to claim 1, wherein the ball seat and the holding member are integrally formed with each other. 4. A pipe through which a predetermined fluid flows, a ball valve according to any one of claims 1 to 3 installed on the pipe, and a pipe on the downstream side of the ball valve, An on-off valve that opens and closes the flow path of the pipe. 5. The ball valve according to claim 1, wherein the on-off valve is the ball valve according to any one of claims 1 to 3.
The fluid supply system described.