JP2003042308A - Valve element seat for metal seat butterfly valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve element seat for a metal seat butterfly valve capable of ensuring sufficient water stopping performance at the time of loading water pressure by making the valve element seat properly engage into a valve casing seat, widely setting a rotating angle range of the valve element capable of keeping a fully closed state, and reducing a necessary operating torque for opening/closing operation. SOLUTION: In this butterfly valve, a thin-wall cylindrical valve casing seat 31 capable of elastically deforming in a diametrical direction is concentrically provided in the inside of a valve casing at specified intervals, and a valve element 22 rotating about an axis of a valve rod 18 radially inserted in the valve casing and the valve casing seat 31 is disposed in the inside of the valve casing seat 31. A valve element seat 32 sliding with the valve casing seat 31 is provided on an outer periphery of the valve element 22. The valve element seat 32 has an outer peripheral diameter larger than the inner peripheral diameter of the valve casing seat 31, and is shaped in an ellipse having a short axis in the axial direction of the valve rod 18 and a long axis in a direction orthogonal to the valve rod 18. A valve element seat surface 32a is linearly contacted with a valve casing seat surface 13a with making a curved surface.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve seat for a metal sheet butterfly valve, and more particularly to a technique for sealing a gap between a valve body and a valve box in a watertight manner. 2. Description of the Related Art Conventionally, in a butterfly valve 11 as shown in FIGS. 5 and 6, for example, a cylindrical valve box sheet 13 is provided inside a valve box 12 so as to be concentric with the axis of a flow passage and mutually. A predetermined gap S is provided between them. A pair of valve box O-rings 14 is provided between the inner surface of the valve box 12 and the outer peripheral surface of the valve box sheet 13 as a valve box sealing material made of an elastic material at positions upstream and downstream of the valve box sheet 13. The valve box O-ring 14 is mounted in an annular groove 15 formed on the inner surface of the valve box 12. A stopper 16 is provided at the upstream end and the downstream end of the valve box sheet 13.
The stopper 16 locks the valve box sheet 13 in the axial direction of the flow path, and is fixed to the valve box 12 by bolts 17. The valve stem 18 penetrates through the boss 19 of the valve box 12 and the through hole 13a of the valve box sheet 13 in a direction orthogonal to the axial direction of the flow path, and is inserted into the boss 19 of the valve box 12.
At 0, it is held rotatably. A plurality of O-rings 21 are arranged on the inner and outer peripheral surfaces of the bearing 20 to seal between the valve stem 18 and the boss 19. The valve body 22 is provided inside the valve box sheet 13 with the valve stem 1.
8 is rotatably arranged around the axis, and the pin 23 is
It is connected to. The valve body 22 is provided with a valve body sheet 24 at a peripheral portion, and the valve body sheet 24 is made of a metal material.
3 is in sliding contact with the valve box seat surface 13b in a watertight manner. The valve body sheet 24 has a shape inclined at a predetermined angle with respect to the cross section of the valve box flow path. Between the valve body 22 and the bush 20, there is provided a ring-shaped valve body-side seal seal material 25 made of a metal material and a valve box-side shaft seal material 26 made of an elastic material of ethylene tetrafluoride resin.
And are arranged. The valve body-side shaft seal material 25 is made of the valve stem 18.
Are disposed on both sides of the valve element 22 in the axial direction, and the valve element sheet 24 is provided between the two valve element-side shaft sealing materials 25. The valve-box-side shaft-sealing material 26 is inserted into the through hole 13a of the valve-box sheet 13, and the valve-box-side shaft-sealing material 26 and the valve-body-side shaft-sealing material 25 are abutted on both tapered surfaces. are doing. An annular pressing plate 27 is disposed on the other end of the bush 20, and the pressing plate 27 is attached to the boss 19 with a tightening bolt 28. By tightening the tightening bolts 28, the valve box-side shaft seal member 26 is pressed against the valve body-side shaft seal member 25 via the holding plate 27 and the bush 20. In the above-mentioned metal touch butterfly valve, the valve box sheet 13 and the valve body sheet 24 are provided.
Is not deformed so much in the fully closed state.
3b and the valve element seat surface 24a are pressed against each other with a predetermined surface pressure to exhibit a sealing function. In order to secure a clearance angle of the valve body sheet 24, as shown in FIG.
In the fully closed state orthogonal to the axis of the valve body 3, the valve body sheet 24 slides on the valve body sheet surface 13b of the valve body sheet 13 over the entire surface of the valve body seat surface 24a formed on the outer peripheral surface thereof. The posture is inclined at a predetermined angle with respect to the flow path cross section. Therefore, the valve body 22 corresponding to the fully closed position
Becomes extremely small, and it is difficult to appropriately hold the valve body 22 at the fully open position. Further, since the valve box sheet 13 expands in the radial direction when a hydraulic pressure is applied, a gap α is formed between the valve body sheet surface 24a and the valve box seat surface 13b.
May occur and the sealing property may be impaired. For this reason, it is required that the valve body 22 is tightened excessively in advance from the fully closed position in consideration of the swelling at the time of hydraulic pressure load so that the valve body sheet 24 bites into the valve box sheet 13. In order to widen the rotation angle range of the valve body 22 that can maintain the state, the valve body sheet 24 is fully closed.
Is required to be arranged in a posture parallel to the cross section of the valve box flow path. In this case, when the valve body sheet 24 having an outer diameter larger than the inner diameter of the valve box sheet is rotated inside the valve box sheet 13 so that the valve body sheet 24 bites into the valve box sheet 13, During the rotation of the valve 22 from the fully open state to the fully closed state, the bite sheet 24 bites into the valve box sheet 13 from a portion closest to the valve stem 18 and gradually to a portion farthest from the valve stem 18, that is, the valve stem. The process is completed at a position shifted by 90 ° in the circumferential direction from 18. Since the portion of the valve box sheet 13 close to the valve rod 18 is held by the valve body-side shaft sealing seal member 25 and the bearing 20 via the valve box-side shaft sealing member 26, it is free in the radial direction. The degree of swelling under hydraulic load is small,
A portion of the valve box sheet 13 which is shifted by 90 ° in the circumferential direction from the valve rod 18 has a large degree of freedom in the radial direction and a large swelling under a hydraulic load. For this reason, it is difficult to make the valve body sheet 24 bite into the valve box sheet 13 over the entire circumference of the valve body sheet 24 at the same level. When the amount is secured, the valve stem 1
In the vicinity of 8, excessive bite occurs and the valve stem 18
If the necessary operating torque required for the rotation operation of the valve becomes large, and if an appropriate bite amount is secured near the valve rod 18, the bite amount will be too small at a position shifted 90 ° in the circumferential direction from the valve rod 18, resulting in a hydraulic load. Sometimes sufficient water stopping performance cannot be secured. The present invention has been made to solve the above-mentioned problems, and by ensuring that a valve body sheet bites into a valve box sheet, sufficient water stopping performance can be ensured at the time of hydraulic pressure load, and a fully closed state can be maintained. It is an object of the present invention to provide a valve seat for a metal seat butterfly valve that can set a wide rotation angle range of a valve body and can reduce an operation torque required for opening and closing operations. [0015] In order to solve the above-mentioned problems, a seat structure of a metal seat butterfly valve according to the present invention is a thin-cylindrical valve box seat which is elastically deformable in a radial direction. The valve body is provided concentrically and with a predetermined gap in the inside of the box, and a valve element that rotates around the axis of a valve rod radially inserted through the valve box and the valve box sheet is arranged in the valve box sheet, In a butterfly valve provided with a valve body sheet slidably in contact with a valve box sheet on the outer periphery of the body, the valve body sheet has an outer diameter larger than the inner diameter of the valve box sheet, and the axial direction of the valve stem has a short axis. In addition, the direction perpendicular to the valve stem has an elliptical shape whose major axis is the long axis, and the valve element seat surface has a curved surface and is in line contact with the valve box seat surface. With the above configuration, in a fully closed state, the valve body sheet surface that forms a curved surface in a posture in which the valve body sheet is perpendicular to the axis of the valve box sheet is in line contact with the valve box sheet surface at its maximum outer diameter position. Then, the valve box sheet is pressed outward and bites in, and the reaction force derived from the elastic deformation of the valve box sheet acts as a sealing pressure to exert a sealing function when the valve body sheet surface and the valve box sheet surface are pressed against each other. . At this time, the valve body sheet has an elliptical shape, and its diameter decreases as it approaches the valve stem in the circumferential direction, and increases as it moves away from the valve stem in the circumferential direction.
The maximum diameter is obtained at a position shifted 90 ° in the circumferential direction from the valve stem. For this reason, in the valve box sheet, a portion close to the valve stem and having a small degree of freedom in the radial direction corresponds to the short axis side of the valve body sheet. The portion having a large degree corresponds to the long axis side of the valve body sheet. Therefore, the operation torque required for opening and closing the valve body can be reduced by preventing the valve body sheet from excessively biting into the valve box sheet at a part close to the valve stem, and at a part shifted 90 ° in the circumferential direction from the valve stem. By securing a predetermined bite amount, sufficient water stopping performance can be secured even when a hydraulic pressure is applied. Further, in the fully closed state, the valve seat is in a posture orthogonal to the axis of the valve box sheet, and the curved valve body sheet surface comes into line contact with the valve box seat surface. The rotation angle range of the valve body that can be maintained can be set widely,
Smooth opening and closing operation of the valve body can be ensured by line contact. Hereinafter, a metal sheet butterfly valve according to an embodiment of the present invention will be described with reference to the drawings. 1 to 3, a metal seat butterfly valve 1 is shown.
1 has the same basic structure as that described above, and members performing the same operation are denoted by the same reference numerals and description thereof is omitted. The valve box sheet 31 has a cylindrical shape made of a thin metal material, and a valve body sheet 32 slidingly contacting the valve box sheet 31 is concentrically formed on the outer periphery of the valve body 22 disposed therein. Is provided between the two valve body-side shaft seal members 25 at the center in the thickness direction. The valve body sheet 32 has a semicircular or semielliptical curved surface whose outer peripheral surface is curved outward in a cross-sectional shape along the radial direction, and the outer peripheral surface forming the curved surface forms a valve body seat surface 32a. ing. The valve body sheet surface 32a has a maximum outer diameter slightly larger than the inner diameter of the valve box seat surface 31a of the valve box sheet 31, and the axial direction A of the valve stem 18 is short as shown in FIG. Along with the axis, a direction B orthogonal to the valve stem 18 has an elliptical shape with a long axis, and the valve body seat surface 32a is curved and linearly contacts the valve box seat surface 31a. The operation of the above configuration will be described below. As shown in FIG. 2, in the fully closed state where the valve body 22 rotates around the axis of the valve stem 18 and the valve body 22 is in a posture orthogonal to the axis of the valve box sheet 31, the valve body sheet 32 is closed. Is also in a posture orthogonal to the axis of the valve box sheet 31. In this state, the valve body sheet 32 comes into line contact with the valve case sheet surface 31a of the valve case sheet 31 at the maximum outer diameter position of the curved valve body sheet surface 32a, and presses the valve case sheet 31 outward. And elastically deform it for a small distance to bite it. The reaction force derived from the elastic deformation of the valve box sheet 31 acts as a sealing pressure, so that the valve body sheet surface 32
a and the valve box seat surface 31a are pressed against each other to exert a sealing function. As described above, the valve body sheet 32 exerts a sealing function by being in line contact with the valve box seat surface 31a on the curved valve body seat surface 32a, so that the valve body seat surface 32a at the time of opening / closing operation is formed. Since the sealing function is maintained by maintaining the pressure contact state while continuously shifting the line contact position, a smooth opening and closing operation of the valve body 22 can be ensured, and the rotation angle range of the valve body 22 corresponding to the fully closed position is large. Therefore, it becomes easy to appropriately hold the valve body 22 at the fully open position. The valve seat 32 has an elliptical shape, and its diameter decreases as it approaches the valve stem 18 in the circumferential direction, and increases as it moves away from the valve stem 18 in the circumferential direction. Since the maximum diameter is obtained at a position shifted by 90 °, the portion of the valve box sheet 31 close to the valve stem 18 and having a small degree of freedom in the radial direction corresponds to the short axis side of the valve body sheet 32, and the circumferential direction from the valve stem 18. A portion having a large degree of freedom in the radial direction shifted by 90 ° corresponds to the long axis side of the valve body sheet 32. Therefore, since the valve body sheet 32 does not bite excessively into the valve box sheet 31 at a position close to the valve rod 18, the operating torque required for opening and closing the valve body 22 can be reduced, as shown in FIG. And 90 from the valve stem 18 in the circumferential direction.
By securing a predetermined bite amount at a part shifted by a degree, sufficient water stopping performance can be secured even when a hydraulic pressure is applied. As shown in FIG. 4, the valve body sheet 32 can be provided in a posture inclined with respect to the center plane of the valve body 22. As described above, according to the present invention, the valve body sheet has an elliptical shape, and the valve box sheet is close to the valve stem and has a small degree of freedom in the radial direction. Corresponding to the shaft side,
By displacing 90 ° in the circumferential direction from the valve stem and corresponding to the long axis side of the valve seat at a portion where the degree of freedom in the radial direction is large, the valve seat is excessively increased relative to the valve box seat at a portion close to the valve stem. The required operating torque required for opening and closing the valve body can be reduced by preventing biting, and by ensuring a predetermined bite amount at a position 90 ° in the circumferential direction from the valve rod, sufficient water stopping performance even under hydraulic pressure load The valve seat is in a position perpendicular to the axis of the valve box seat in the fully closed state, and the valve seat sheet surface, which forms a curved surface, is in line contact with the valve box seat surface to maintain the fully closed state. The rotation angle range of the valve body that can be set can be set wide, and the smooth opening and closing operation of the valve body can be ensured by line contact.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing a main part of a metal sheet butterfly valve according to an embodiment of the present invention. FIG. 2 is a plan sectional view of the metal seat butterfly valve. FIG. 3 is a schematic view showing a main part of the metal seat butterfly valve. FIG. 4 is a plan sectional view of the metal seat butterfly valve. FIG. 5 is a cross-sectional view showing a conventional metal seat butterfly valve. FIG. 6 is a plan sectional view of the metal seat butterfly valve. FIG. 7 is an enlarged view showing a main part of the metal seat butterfly valve. [Description of Signs] 11 Butterfly valve 12 Valve box 18 Valve rod 22 Valve element 31 Valve box sheet 31a Valve box sheet surface 32 Valve element sheet 32a Valve element sheet surface

Claims (1)

Claims: 1. A valve box sheet having a thin cylindrical shape and elastically deformable in a radial direction provided concentrically and with a predetermined gap in a valve box. In a butterfly valve, a valve body that rotates around an axis of a valve rod radially inserted through a box sheet is disposed in the valve box sheet, and a valve body sheet that slides on the valve box sheet is provided on the outer periphery of the valve body. The body sheet has an outer diameter larger than the inner diameter of the valve box sheet, and has an elliptical shape in which the axial direction of the valve stem forms a short axis and the direction orthogonal to the valve stem forms a long axis,
A valve seat for a metal seat butterfly valve, wherein the valve seat has a curved surface and is in line contact with the valve box seat.