JP2001248738A - Seat structure of eccentric butterfly valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seat structure of an eccentric butterfly valve capable of enhancing a flexibility and a durability by enhancing a followability against a motion of a valve element. SOLUTION: The seat structure of an eccentric butterfly valve is provided with a valve case 1 having a cylindrical passage 1A; a valve rod 2 eccentrically disposed perpendicularly to an axis of a flow passage of the valve case 1; a valve element 3 having a valve element surface at a position left from the valve rod 2 by a predetermined distance and rotated around an axis of the valve rod 2 to open/close the flow passage 1A; an annular recessed portion 4 formed on an inner periphery surface of the valve case 1 and opened opposed to the valve element 3 in the direction of the axis c of the flow passage; an annular valve case seat 6 movably disposed on the annular recessed portion 4 along a direction of the axis c of the flow passage and abutted to a valve element seat 3a formed on a periphery edge of the valve element 3; a bellows 5 urging the valve case seat 6 toward the valve element 3; and an O ring 7 for sealing a space between inner periphery surfaces at both sides of the annular recessed portion 4 and inner and outer periphery surfaces of the valve case seat 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seat structure of an eccentric butterfly valve, and relates to a technique for preventing deformation of a seat member.

[0002]

2. Description of the Related Art Conventionally, in a general eccentric butterfly valve of this kind, a valve body sheet is formed on a peripheral portion of a valve body, and an annular valve box sheet which is in contact with the valve body sheet is disposed in a valve box. When the valve is fully closed, sealing is ensured by pressure contact between the valve body sheet and the valve box sheet.

[0003] Specifically, in the joining / separating operation between the valve body sheet and the valve box sheet at the time of opening / closing operation of the valve body, flexibility is ensured by the elasticity of the valve box sheet, and the seat surface pressure is reduced. It is secured by the elasticity derived from the elastic deformation of the sheet. The valve box sheet includes a rubber soft seal ring and a metal seal ring.

[0004]

However, in the conventional eccentric butterfly valve seat structure, when the valve body moves more than the elastic deformation allowed by the valve box sheet, the valve body excessively bites into the valve box sheet. In particular, in the case of a metal seal ring, the valve box sheet may be plastically deformed, and a sufficient surface pressure may not be secured.

[0005] The present invention is to solve the above problems,
An object of the present invention is to provide a seat structure of an eccentric butterfly valve capable of realizing an improvement in flexibility and durability by improving the followability to the movement of a valve element.

[0006]

In order to solve the above problems, a seat structure of an eccentric butterfly valve according to the present invention comprises a valve box having a cylindrical flow path and a flow path axis in the valve box. A valve stem having a valve body surface at a position spaced a predetermined distance from the valve stem, rotating around the axis of the valve stem to open and close the flow path, and a flow path inner peripheral surface of the valve box An annular concave portion that is formed to face the valve body in the axial direction of the flow path, and is disposed movably along the axial direction of the flow path in the annular concave portion, and is provided on a valve body sheet formed on a peripheral portion of the valve body. An annular valve box sheet to be abutted, an elastic body disposed in the annular recess and pressing the valve box sheet toward the valve body, and a gap between the inner peripheral surfaces on both sides of the annular concave portion and the inner and outer peripheral surfaces of the valve box sheet. And a sealing material for sealing.

According to the above-described structure, in the fully closed state of the valve body, the valve box sheet receives the elasticity of the elastic body without being elastically deformed and abuts on the valve body sheet to secure the surface pressure. . Further, since the valve body sheet follows the movement of the valve body due to the pressure change after the fully closed state by the expansion and contraction of the elastic body, excessive biting of the valve body and plastic deformation of the valve body sheet itself can be prevented.

When the valve element is opened, the valve box sheet which is in contact with the valve element sheet is pushed by the valve element which rotates about the axis of the valve rod, and retreats in the axial direction of the flow path against the elasticity of the elastic body. Since smooth operation of the body is ensured, excessive biting of the valve body and plastic deformation of the valve box sheet itself can be prevented, and excessive operating torque is not generated.

Further, since the elastic body is arranged in the annular concave portion formed on the inner peripheral surface of the flow path of the valve box, the elastic body does not come into direct contact with the fluid, and the durability is excellent.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3, the valve box 1 has a cylindrical flow path 1A. A circular valve element 3 that rotates around the axis of a valve stem 2 that is perpendicular and eccentric to the flow path axis c is disposed in the flow path 1A.
Has a valve body surface at a position separated from the valve stem 2 by a predetermined distance, and rotates around an axis with the rotation operation of the valve stem 2 to open and close the flow path 1A.

On the inner peripheral surface of the flow passage 1A of the valve box 1, there is formed an annular concave portion 4 which is opened facing the valve body 3 in the direction of the flow passage axis c. A bellows 5 forming a bellows-like elastic body is disposed in the annular concave portion 4 so as to be elastically expandable and contractable in the direction of the flow path axis c, and a metal seal is provided on the opening side of the annular concave portion 4. An annular valve box sheet 6 made of a ring or the like is movably disposed along the direction of the flow channel axis c, and the valve box sheet 6 is pressed toward the valve element 3 by the bellows 5. The valve box sheet 6 abuts the concave or spherical tapered sealing surface formed on the inner peripheral edge of the front end with the convex spherical or tapered valve body sheet 3a formed on the peripheral edge of the valve element 3. As a result, a sealing property is exhibited, and an O-ring 7 seals between the inner peripheral surfaces of both sides of the annular recess 4 and the inner and outer peripheral surfaces of the valve box sheet 6.

According to the above-described configuration, in the fully closed state of the valve body 3, the valve box sheet 6 receives the elastic force of the bellows 5 without elastic deformation of itself, and comes into contact with the valve body sheet 3a to come into contact with the valve body sheet 3a. Ensure pressure.

Further, the valve box sheet 6 moves in the direction of the flow axis c by following the expansion and contraction of the bellows in response to the movement of the valve element 3 caused by the pressure change after the valve is fully closed.
Excessive biting of the valve body 3 and plastic deformation of the valve box sheet 6 can be prevented.

When the valve body 3 rotates to the fully open position as shown by the imaginary line in FIG. 1, the valve box sheet 6 abutting on the valve body sheet 3a pushes the valve body 3 rotating about the axis of the valve stem 2. And retreats in the direction of the flow path axis c against the elasticity of the bellows 5,
Since smooth operation of the valve body 3 is ensured, excessive biting of the valve body 3 and plastic deformation of the valve box sheet 6 can be prevented, and excessive operating torque is not generated. The bellows 5 has an annular recess 4.
Since it is arranged inside, it is excellent in durability without directly contacting the fluid.

[0015]

As described above, according to the present invention, the valve box sheet closely adheres to the valve body while moving following the movement of the valve body, so that the valve box sheet has a sufficient surface without elastic deformation. The pressure can be secured, and the valve body does not excessively bite into the valve box sheet, and the valve box sheet itself is not plastically deformed and surface pressure loss is prevented. For this reason, the flexibility of the valve box sheet with respect to the movement of the valve body can be improved, and the sealing performance and durability can be improved over many years.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an eccentric butterfly valve showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the eccentric butterfly valve.

FIG. 3 is an enlarged view of a main part of the eccentric butterfly valve.

[Explanation of symbols]

 c Flow path axis 1 Valve box 1A Flow path 2 Valve rod 3 Valve element 3a Valve element sheet 4 Annular recess 5 Bellows 6 Valve box sheet 7 O-ring

Claims (1)

[Claims] A valve body having a cylindrical flow path, a valve stem disposed perpendicular to an axis of a flow path in the valve case, a valve body surface at a position spaced a predetermined distance from the valve stem, and a valve. A valve body that rotates about the axis of the rod to open and close the flow path, an annular recess formed on the inner peripheral surface of the flow path of the valve box, and opened to face the valve body in the flow axis direction, and an annular recess. An annular valve box sheet that is movably disposed along the flow path axis direction and abuts on a valve element sheet formed on the peripheral edge of the valve element, and is disposed in an annular concave portion, and the valve box sheet faces the valve element. An eccentric butterfly valve seat structure, comprising: an elastic body to be pressed; and a seal member for sealing between inner peripheral surfaces on both sides of an annular concave portion and inner and outer peripheral surfaces of a valve box sheet.