JP2003014139A - Butterfly valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a butterfly valve, in which a valve element peripheral portion almost simultaneously abuts on protrusions of a seat ring. SOLUTION: By gradually varying inclination of a pressure contact surface 28 of the protrusion 26, the pressure contact surface 28 in the vicinity of a valve shaft 3 is sharply inclined, and the surface 28 far from the valve shaft 3 is gently inclined. The abutting portion 31 of the pressure contact surface 28 abutting on the peripheral portion of the valve element 2 is expanded to an opening direction side more in a portion far from the valve shaft 3 than in the vicinity of the valve shaft 3. The peripheral portion of the valve element 2 almost simultaneously abuts on an abutting portions of protrusions 26 of the peripheral portion of the valve element 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a butterfly valve for opening and closing a valve and adjusting a flow rate by rotating a valve element mounted in a valve box around a valve shaft.

[0002]

2. Description of the Related Art Generally, in a butterfly valve, a substantially disc-shaped valve element mounted in a valve box is rotated around a valve axis passing through the diametrical direction of the valve element to open / close the valve or control the flow rate. A seat ring made of a rubber-like elastic body is attached to the inner peripheral surface of the valve box for adjustment. When the valve is closed, the seat ring is pressed by the peripheral edge of the valve body that rotates around the valve axis so that the plate surface is orthogonal to the flow path direction (in the closing direction). Seal between the spaces.

FIG. 8 shows an example of a seat ring. The seat ring 101 has a substantially U-shaped cross section with an open outer surface, and the outer surface side is fitted into a protrusion on the inner peripheral surface of the valve box and mounted on the valve box. A ridge 102 is formed on the inner peripheral surface of the valve body 103 so as to continuously project inward in the circumferential direction. The ridge 102 is pressed against the peripheral edge of the valve body 103 to seal the gap with the valve body 103. To do.

In the seat ring of the type in which the peripheral edge portion of the valve body is pressed outward in the radial direction of the flow path, the peripheral edge portion of the valve element is contacted until the predetermined pressure contact deformation amount is obtained after the peripheral edge portion of the valve element abuts. However, since the seat ring slides in the closing direction while being pressed outward in the radial direction of the flow path, the torque required for closing the valve increases due to the frictional force at this time.

On the other hand, the seat ring 1 shown in FIG.
In No. 01, the protrusion 102 on the inner peripheral surface thereof is pressed against the peripheral edge of the valve element 103 in the closing direction to seal, so that the frictional force at the time of valve closing is minimized and the torque required for valve closing is reduced. You can

That is, in this seat ring, the valve body 103 in the open state (X) is rotated around the valve shaft 104 in the closing direction to bring the valve body 103 into contact with the ridge 102 (Y). ), The valve body 103 further rotates in the closing direction to reach the closed state (Z). Contact state (Y)
When shifting from the closed state (Z) to the closed state (Z), the peripheral edge portion of the valve element 103 slides on the surface of the protrusion 102, but since it is not positively pressed outward in the radial direction of the flow path, the frictional force at the time of closing the valve becomes small. .

In the closed state (Z), a reaction force that pushes back the peripheral edge portion of the valve element 103 in the opening direction is generated in the portion (the range of the height H) extruded in the closing direction of the ridge 102, and this reaction force is generated. Sealed by overcoming fluid pressure.

This reaction force causes the valve element 103 to come into contact (Y).
Since it increases in accordance with the amount of pressure contact deformation (L) when moving from the closed state (Z) to the closed state (Z), the amount of pressure contact deformation (L) of the protrusion 102 is substantially constant in the circumferential direction. Have the same cross-sectional shape. This ridge 102 is connected to the valve shaft 104
When viewed in the direction of, the contact portion 105 forms a straight line parallel to the axis line 106 of the ridge 102, is substantially parallel to the peripheral edge portion of the valve element 103 in the closed state (Z), and its interval is pressure-contact deformed. It becomes the quantity (L).

[0009]

However, when viewed in the valve axis direction, the peripheral portion of the valve body forms a straight line passing through the valve shaft, and the straight line of the peripheral portion of the valve body rotates around the valve shaft. Since the straight line of the peripheral edge of the valve element does not overlap with the straight line formed by the abutting part, the peripheral edge of the valve element does not contact the protrusion at the same time when the valve is closed. The contact time is shifted.

That is, the movement amount of the valve body peripheral portion when the valve body is rotated around the valve shaft is proportional to the distance from the valve shaft in the direction orthogonal to the valve shaft, and the movement amount is the compression deformation amount. Since the rotation angle of the valve body that is equal to (L) is larger near the valve shaft than near the center between the valve shafts, when the vicinity of the center is in the contact state (Y), the ridges are formed near the valve shaft. It has been pressed to some extent.

However, even if the ridge near the valve shaft is pressed to some extent, sealing cannot be performed until the rim near the center of the ridge contacts the rim near the center of the valve. The pressure contact of the ridge near the valve shaft from the contact to the contact in the vicinity of the center does not contribute to the sealing, and is a factor that unnecessarily increases the torque when the valve is closed.

Further, when the valve body is rotated in the closing direction to reduce the flow rate, the peripheral edge of the valve body is likely to come into contact with the protrusion near the valve shaft, and therefore the seal ring may be deteriorated at this portion. was there.

[0013]

In view of the above-mentioned problems, the present invention is mounted on the inner peripheral surface of the valve box of a butterfly valve, and when the valve is closed,
Assuming a seat ring that seals between the inner peripheral surface of the valve box and the valve body, two valve shaft holes for penetrating the valve rod are formed so as to oppose each other in the radial direction of the flow path. A boss is formed around the boss, and a ridge protruding inward continuously in the circumferential direction is formed between the bosses so that the valve body is pressed against the peripheral edge of the valve in the closing direction when the valve is closed. There is provided a seat ring in which the peripheral edge portion of the valve body is brought into contact with the abutting portion of the protrusion at substantially the same time, and a butterfly valve equipped with the seat ring.

If the contact portion is formed in a curved shape in which the portion apart from the boss portion in the circumferential direction bulges in the opening direction side, unlike the case where the protrusion having the same cross-sectional shape in the circumferential direction is adopted, the peripheral edge portion of the valve body is The contact portions of the ridges can be brought into contact with each other substantially simultaneously. That is,
When the ridges have the same cross-sectional shape in the circumferential direction and the contact portions are parallel to the axis of the ridges, the peripheral edge of the valve body moving in the closing direction first contacts the ridges near the boss, After that, the portion apart from the boss portion abuts, but by inflating the portion away from the boss portion, the peripheral edge portion of the valve body abuts the abutting portion of the protrusion substantially at the same time in the circumferential direction.

If the cross-sectional areas of the ridges that are pressed against the peripheral edge of the valve body when the valve is closed and are pushed out in the closing direction have substantially the same cross-sectional area in the circumferential direction, the amount of press contact deformation in the closing direction is small. In the portion, the contact height with the peripheral portion of the valve body is increased accordingly, and the sealing function can be made substantially the same in the circumferential direction.

That is, when the abutting portion of the ridge is inflated toward the opening side, the amount of press-contact deformation of the ridge in the closing direction from the abutting state to the closed state is larger than that in the vicinity of the boss portion. The reaction force per unit area at the portion where the ridges closely contact the peripheral edge of the valve element and push back the valve element in the opening direction is small near the boss portion and is large near the center,
As a result, the contact height increases, so that the sealing function is substantially the same in the circumferential direction.

In addition, when the opening side of the ridge which is pressed against the peripheral edge of the valve body when the valve is closed is used as an inclined surface, a steep slope is formed near the boss and a gentle slope is formed in a portion away from the boss. By changing the slope of the inclined surface, it is possible to make the cross-sectional areas of the portion pressed against the peripheral edge of the valve body when the valve is closed and pushed out in the closing direction substantially the same in the circumferential direction.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a butterfly valve according to the present invention will be described below with reference to the drawings. Figure 1
Is a front view of the butterfly valve of the present invention, and FIG. 2 is a sectional view taken along line AA. 3 is a sectional view of the seat ring in the valve axis direction, and FIG. 4 is a sectional view of the seat ring in the direction perpendicular to the valve axis.

This butterfly valve is interposed in a connecting portion of a pipe through which a fluid flows, to open and close the flow passage and adjust the flow rate, and to clamp the pipe in the axial direction (flow passage direction). A ring-shaped valve box 1, a substantially disc-shaped valve element 2 installed inside the valve box 1, a valve element 2 which is a valve shaft 3 (the center of the valve box 1 in a direction orthogonal to the flow direction). And a valve rod 2 mounted on the inner peripheral surface of the valve box 1 to seal the space between the inner peripheral surface of the valve box 1 and the valve body 2. The seat ring 4 is provided.

The valve box 1 is made of, for example, steel and has a cylindrical flange 6 on the inner side of the inner peripheral surface of a cylindrical valve box body 5 that is pinched in the flow direction by both pipes. 7 are continuously formed in the circumferential direction. A ring-shaped groove is formed in the center of the inner peripheral surface of the protrusion 7 to prevent the seat ring 4 from slipping in the flow path direction by fitting a slip stopper 19 of the seat ring 4 which will be described later.

On the one side and the other side of the valve box 1 in the direction of the valve shaft 3, one side and the other side bearings 8a, 8b having shaft holes penetrating from the outer side surface to the inner peripheral surface of the protrusion 7 are provided on the outer side. One side and the other side valve rods 3a and 3b that are formed to project toward one side and are fitted in the shaft holes.
Is rotatably held.

A tubular valve rod cover 9 made of, for example, steel is fitted in the portion of the one-sided bearing 8a projecting outward from the valve body 5 to be integrated with the one-sided bearing 8a, and the inside thereof. The one-sided valve rod 3a is inserted therethrough. Valve stem cover 9
An outer peripheral flange 10 is fixed to one end portion of the one end of the screw 1.
It is attached at 2.

Further, the one side bearing 8 is arranged in the circumferential direction of the valve box body 5.
Positioning pieces 13 are formed on both sides of a. A bolt through hole 14 is formed in this positioning piece 13,
When connecting the pipes, the valve box 1 is positioned by passing the pipe connecting bolts through the bolt through holes 14, and the plate box 1 can be easily interposed between the pipes.

On the outer surface of the bearing 8b on the other side, a lid plate 15 made of, for example, steel is fixed by screws 17 with a thin plate 16 made of a rubber-like elastic material interposed, and the valve rod 3b on the other side comes out. Is blocked, and the outer side of the shaft hole is closed so that the fluid does not leak to the outside through the shaft hole.

The valve body 2 is made of steel, for example, and has a substantially disk shape whose diameter is smaller than the inner diameter of the projection 7 of the valve box 1. The inside of the valve box 1 is aligned with the diametrical direction of the valve shaft 3. To be equipped with. The valve body 2 is rotated around the valve shaft 3 to direct the plate surface in a direction parallel to the flow path direction to open the flow path, and to direct the plate surface in a direction perpendicular to the flow path direction. Thus, the flow path is closed, and the flow rate is adjusted by appropriately changing the angle of the plate surface.

In the direction of the valve shaft 3, near the periphery of one side and the other side of the valve body 2, the bag-shaped one side and the other side valve rod fitting portions 18a, 1
8b is formed, and this one side and the other side valve rod fitting portion 1 is formed.
The valve body 2 is supported inside the valve housing 1 by fitting the vicinity of the tip portions of the one-side and the other-side valve rods 3a, 3b to the 8a, 18b. The hole of the one-side valve rod fitting portion 18a is substantially square, and the hole of the other-side valve rod fitting portion 18b is circular.

The one-sided valve rod 3a is made of, for example, steel and has a circular cross section, and is fitted into the one-sided bearing 8a and the valve rod cover 9. The vicinity of one end of this one-side valve rod 3a is formed in a substantially square cross section and protrudes from the valve rod cover 9. A handle (not shown) is attached to the one-side valve rod 3a around its axis (the valve shaft 3). It can be rotated around).

The vicinity of the other end of the one-side valve rod 3a is formed in a substantially square cross section and protrudes inward of the valve box 1 to form the valve body 2.
It is fitted in a substantially square hole of the one side valve rod fitting portion 18a, and the valve body 2 is rotated around the valve shaft 3 by rotating the one side valve rod 3a around its axis. Is able to.

A groove which is continuous in the circumferential direction is formed in a portion of the circular cross section of the one side valve rod 3a located near one side end of the valve rod cover 9. Divided removal preventing member 11 having a circular hole so that the inner edge portion is fitted into this groove 11
Is attached to the outer peripheral flange 10 to prevent the one-side valve rod 3a from coming off.

The other side valve rod 3b is made of, for example, steel and has a circular cross section, and is fitted in the other side bearing 8b. The vicinity of one end of the other side valve rod 3b protrudes inward of the valve box 1 and is fitted into the circular hole of the other side valve rod fitting portion 18b of the valve body 2 and Is rotatably supported around the valve shaft 3.
The other side end of the other side valve rod 3b is pressed by a cover plate 15 fixed to the outer surface of the other side bearing 8b with a thin plate 16 made of a rubber-like elastic material interposed therebetween. Movement is regulated.

The seat ring 4 is formed of a rubber-like elastic body in a ring shape having a substantially U-shaped cross section with an open outer surface. The outer side of the seat ring 4 is bent inward so that the flange 6 of the protrusion 7 is formed. It is attached to the inner peripheral surface of the valve box 1 so as to be hugged. The outer diameter of the main body of the seat ring 4 is set to fit into the valve box main body 5, and the inner diameter thereof is made larger than the diameter of the valve body 2.

At the central portion on the outer surface side of the seat ring 4, a shift stopper 19 is formed so as to continuously project in the circumferential direction and is fitted into a ring-shaped groove formed in the protrusion 7 of the valve box 1 to open and close the valve. It prevents the shift in the flow direction due to.

Two valve shaft holes 20 for penetrating the one side and the other side valve rods 3a, 3b are formed at positions (positions where the valve shaft 3 passes) of the seat ring 4 which face each other in the radial direction of the flow path. Has been done. On the inner peripheral surface of the valve shaft hole 20, a valve rod seal portion 21 that continuously protrudes in the circumferential direction is formed near the center in the valve shaft 3 direction, and one-side valve and another-side valve that penetrate the valve shaft hole 20 are formed. A seal is provided between the rods 3a and 3b. Also, the valve shaft hole 2
A ring-shaped reinforcing member 22 is embedded around 0.

Around the valve shaft hole 20, a boss portion 23 is formed so as to inwardly seal the valve body 2 in the vicinity of the valve shaft 3 so as to project inward. The boss portion 23 has a substantially circular sliding surface 24 on which the end surfaces of the valve body 2 on one side and the other side valve rod fitting portions 18a and 18b slide, and from the sliding surface 24 to the inside of the seat ring 4 main body. It is composed of a taper portion 25 that slides on the peripheral surface. The sliding surface 24 and the valve rod fitting portions 18a, 18 on one side and the other side of the valve body 2
The end surface of b is a spherical surface in which the sliding surface 24 is concave and the end surfaces of the one-side and the other-side valve rod fitting portions 18a and 18b are convex so that they are in close contact with each other, and both have substantially the same size. Is formed.

A ridge 26 is formed between the boss portions 23 on one side and the other side so as to continuously project inward in the circumferential direction.
The protrusion 26 has an inward top 27, a pressure contact surface 28 in the opening direction (the direction in which the valve element 2 moves when the valve is opened), and a closing direction (the direction in which the valve element 2 moves when the valve is closed). The protective surface 29 on the side is formed into a substantially trapezoidal cross section. Since the valve is opened and closed by the rotation of the valve body 2 around the valve shaft 3, the boss portion 2
In the two protrusions 26 between 3, the opening direction and the closing direction are opposite to each other.

The top portion 27 has a constant height in the circumferential direction from the inner circumferential surface of the body of the seat ring 4, is parallel to the flow path direction,
It consists of a part of a cylindrical surface having a constant width in the flow path direction. This top 2
The inner diameter of the cylinder formed by 7 is smaller than the diameter of the valve body 2 so that the peripheral edge portion of the valve body 2 can press-contact the ridge 26. The top portion 27 has a shape that prevents the entire protrusion 2 from being easily deformed when the protrusion 26 is pressed against the peripheral edge of the valve body 2.
From the position (the axis of the ridge) to the closing direction side with a predetermined width.

The pressure contact surface 28 is an inclined surface that slides from the top portion 27 to the inner circumferential surface of the seat ring 4 on the main body opening direction side, and is pressed against the peripheral edge of the valve body 2 in the closing direction. The pressure contact surface 28 is parallel to the flow path direction near the top 27,
The curved surface is inwardly convex, and is formed by gradually changing the gradient in the circumferential direction so that the vicinity of the boss portion 23 is steep and the vicinity of the center between the boss portions 23 is gentle.

Due to this change in gradient, the vicinity of the tip of the press contact surface 28 (the intersection with the inner peripheral surface of the body of the seat ring 4) is proportional to the distance from the valve shaft 3 in the direction orthogonal to the valve shaft 3. Thus, the vicinity of the center between the boss portions 23 has a curved shape that bulges toward the opening direction. When viewed in the valve shaft 3 direction, near the tip of the press contact surface 28, a straight line is formed in which the vicinity of the center between the bosses 23 is inclined toward the opening direction.

The protective surface 29 is an inclined surface with a constant slope that slides from the top portion 27 to the inner peripheral surface of the seat ring 4 main body in the closing direction, and when the pressure contact surface 28 is pressed against the peripheral edge portion of the valve body 2. , The entire ridge 26 is protected from deformation in the closing direction.

Next, the manner in which the ridge of the seat ring seals the valve body will be described. FIG. 5 is a cross-sectional view of an essential part showing a state in which the peripheral edge portion of the valve body presses the ridge, FIG. 6 is a view for explaining the relationship of the pressure contact state near the boss portion and the center between the boss portions, and FIG. It is a figure explaining the relationship between reaction force and fluid pressure.

When the valve body 2 in the open state (X) is rotated around the valve shaft 3 in the closing direction to move to the abutting state (Y), the closing direction side edge portion 30 of the valve body 2 is protruded. Abutting against the press contact surface 28. At this time, the angle (θ) formed by the plate surface of the valve body 2 with respect to the direction orthogonal to the flow path direction is small, and the distance from the inner peripheral surface of the main body of the seat ring 4 to the closing side edge portion 30 of the valve body 2 is small. The inward height (h) is the radius (R1) of the inner peripheral surface of the seat ring 4 body.
Is approximately equal to the difference (R1-R2) between the radius (R2) of the valve body 2 and the radius (R2) of the valve body 2. That is, on the pressure contact surface 28, a portion having a predetermined height (h) from the inner peripheral surface of the main body of the seat ring 4 becomes the contact portion 31.

The contact portion 31 has a curved shape in which the gradient of the pressure contact surface 28 gradually changes and the vicinity of the center between the boss portions 23 bulges in the opening direction side, and the side edge of the valve body 2 in the closing direction. The end portion 30 abuts the abutting portion 31 of the press contact surface 28 substantially at the same time. That is,
When viewed in the direction of the valve shaft 3, the contact portion 31 is a straight line that passes through the valve shaft 3 and the vicinity of the center between the bosses 23 is inclined toward the opening direction side. Since the straight lines formed by the portions 30 substantially overlap with each other, the closing direction side edge portion 30 of the valve body 2 contacts the contact portion 31 at substantially the same time.

After that, the valve body 2 is rotated to be in a contact state (Y).
From the closed state (Z) to the valve body 2 when viewed in the direction of the valve shaft 3
The straight line formed by the peripheral edge portion of the is substantially parallel to the axis of the ridge 26, and the ridge 26 is pressed against the peripheral edge portion of the valve body 2 in the closing direction by the pressure contact deformation amount (L). At this time, a part of the ridge 26 is pushed out in the closing direction, and is brought into close contact with the peripheral edge portion of the valve body 2 within the range of the contact height (H) so as to push the valve body 2 back in the opening direction. Seal between 2 and.

In the closed state (Z), the fluid on the upstream side enters the close contact portion between the protrusion 26 and the peripheral portion of the valve body 2 and tries to flow out to the downstream side while spreading the close contact portion. The pressure (P) of this fluid gradually decreases along the contact surface due to the frictional resistance, and this fluid pressure (P) has a magnitude per unit area of the reaction force of the protrusion 26 that pushes back the valve body 2 ( At a position below S), the invasion of the fluid is blocked, and the periphery of the valve body 2 is sealed.

That is, the contact height (H) can be increased to reduce the fluid pressure (P), or the size (S) of the reaction force of the ridge 26 per unit area can be increased to prevent intrusion. The sealing function is improved by increasing the fluid pressure (P).

Since the magnitude (S) of the reaction force of the protrusion 26 that pushes back the valve body 2 per unit area increases in accordance with the pressure contact deformation amount (L), this pressure contact deformation amount (L) and the contact height. By increasing (H) and increasing the cross-sectional area (A) of the extruded portion of the protrusion 26, the sealing function is improved. The cross-sectional area (A) of the extruded portion of the ridge 26 is calculated by (A1) = (L × H / 2) using the pressure contact deformation amount (L) and the contact height (H). expressed.

The pressure contact deformation amount (L) increases as the contact portion 31 expands in the opening direction, and the contact height (H) becomes
It increases according to the gradient of the pressure contact surface 28. Where ridge 2
The pressure contact surface 28 of 6 has a shape in which the contact portion 31 bulges toward the opening side near the center between the boss portions 23 by gradually changing the gradient so that the vicinity of the boss portion 23 becomes steep. And the contact height (H) at the position where the amount of press contact deformation (L) is large.
Is small, and the contact height (H) is large at a position where the amount of press contact deformation (L) is small. Therefore, the cross-sectional areas (A) are substantially the same in the circumferential direction, and the sealing functions are substantially the same in the circumferential direction.

The pressed ridge 26 is deformed so that the peripheral side of the valve body 2 in the closing direction rises, and comes into close contact with the surface of the peripheral side of the valve body 2 in the closing direction. On the other hand, on the opening direction side with respect to the closing direction side edge portion 30, it is pulled toward the closing direction side by some frictional force with the valve body 2, and a slight gap is formed between the edge surface 30 and the end surface of the valve body 2. . Accordingly, the close contact between the surface of the peripheral edge of the valve body 2 on the closing direction and the ridge 26 seals the gap between the valve body 2 and the valve body 2.

According to the above structure, the ridge 26 has the boss portion 2
The contact portion 31 has a shape that bulges toward the opening direction near the center between the three, and the peripheral edge portion of the valve body 2 contacts the contact portion 31 substantially at the same time when the valve is closed. Therefore, the torque required until the entire peripheral portion of the valve body 2 comes into contact with the protrusion 26 becomes small.

The slope of the pressure contact surface 28 of the protrusion 26 is gradually changed so that the slope is steep near the boss portion 23 and is gentle near the center between the boss portions 23.
In the portion having a gentle slope, the contact portion 31 swells toward the opening direction side. Therefore, the portion pushed out at the peripheral portion of the valve body 2 when the valve is closed has a circumferential sectional area (A) determined by the contact height (H) to the peripheral portion of the valve body 2 and the pressure contact deformation amount (L). They are substantially the same, and their sealing functions can be made substantially the same in the circumferential direction.

The present invention is not limited to the above-mentioned embodiment, and appropriate modifications can be made within the scope of the present invention. For example, the top 27 of the ridge 26
In addition to keeping the width constant, the width may be changed so that the vicinity of the center between the boss portions 23 is expanded toward the opening direction. In this case, the peripheral edge portion of the valve body 2 can be brought into contact with the protrusions 26 substantially at the same time without changing the gradient of the pressure contact surface 28.

Further, the top portion 27 of the ridge 26 not only makes the height of the seat ring 4 from the inner peripheral surface of the main body constant, but also changes the height so that the peripheral edge of the valve body 2 is closed. The cross-sectional areas of the portions pressed against each other and pushed out in the closing direction may be substantially the same in the circumferential direction. In this case, the pressure contact surface 2
The sealing function can be made substantially the same in the circumferential direction without changing the gradient of 8.

[0053]

As is apparent from the above description, according to the present invention, the ridge that is pressed against the peripheral portion of the valve body has a shape in which the contact portion bulges in the opening direction side. The peripheral portion can be brought into contact with the ridge substantially at the same time. As a result, it is possible to eliminate the pressure contact until the contact of the peripheral edge of the valve element with the ridge is completed, and it is possible to eliminate unnecessary torque that does not contribute to sealing. Further, when the valve body is rotated around the valve shaft to reduce the flow rate, the peripheral edge portion of the valve body near the valve shaft is prevented from coming into contact with the ridge, and the durability thereof can be improved.

Further, by gradually changing the gradient of the pressure contact surface,
By increasing the contact height of the portion where the press contact deformation amount is small, it is possible to make the cross-sectional areas of the portion pressed and pressed in the closing direction at the peripheral portion of the valve body 2 at the time of valve closing in the circumferential direction substantially the same. The sealing function can be made substantially the same in the circumferential direction to eliminate unnecessary pressure contact.

[Brief description of drawings]

FIG. 1 is a front view of a butterfly valve of the present invention.

FIG. 2 is a sectional view taken along line AA.

FIG. 3 is a sectional view of the seat ring in the valve axis direction.

FIG. 4 is a sectional view of the seat ring in the direction perpendicular to the valve axis.

FIG. 5 is a cross-sectional view of a main portion showing a state in which the peripheral edge portion of the valve body presses against the ridge.

FIG. 6 is a diagram for explaining the relationship of the pressure contact state near the boss portion and near the center between the boss portions.

FIG. 7 is a diagram illustrating a relationship between a reaction force of a pressure contact surface and a fluid pressure.

FIG. 8 is a sectional view of a main part of a conventional seat ring.

[Explanation of symbols]

1 valve box 2 valve body 3 valve shaft 4 seat ring 23 Boss 26 ridges 27 top 28 Pressure contact surface 29 Protective surface 31 abutment

Claims (4)

[Claims] 1. A butterfly valve mounted on an inner peripheral surface of a valve box,
A seat ring that seals between the inner peripheral surface of the valve box and the valve body when the valve is closed, and two valve shaft holes for penetrating the valve rod are formed to face each other in the radial direction of the flow path. Between the bosses around the shaft hole, there is formed a ridge that continuously projects inward in the circumferential direction and is pressed against the rim of the valve body in the closing direction when the valve is closed. The seat ring, wherein the abutting portion that abuts has a curved shape in which a portion apart from the boss portion in the circumferential direction bulges toward the opening direction so that the peripheral edge portion of the valve body abuts substantially simultaneously. 2. The seat according to claim 1, wherein the ridges have substantially the same cross-sectional area in the circumferential direction at the portion pressed against the peripheral edge of the valve body and pushed out in the closing direction when the valve is closed. ring. 3. The protrusion has an inclined surface on the opening side which is pressed against the peripheral edge of the valve body when the valve is closed, and the inclined surface has a steep slope near the boss portion and a gentle slope at a portion away from the boss portion. The seat ring according to claim 1 or 2, wherein the seat ring is formed by changing the slope in the circumferential direction so as to have a slope. 4. A butterfly valve, comprising the seat ring according to claim 1, 2, or 3.