JP2003056721A - Structure of shaft seal part of butterfly valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure of a shaft seal part of a butterfly valve capable of reducing factors for damaging a shaft seal material in a valve casing side and impeding the rotating motion of a valve element. SOLUTION: A valve stem 18 is disposed by being inserted into a through-hole 13a of a valve casing seat 13 disposed inside the valve casing 12 and a valve element seat 24 in sliding contact with the valve casing seat 13 is provided in the outer circumference of the valve element 22 rotating around the axis of the valve stem 18. A shaft seal member 32 in the valve element side is disposed in a recess part 22a of the valve element formed in the circumference of the valve stem 18, and the shaft seal material 31 in the valve casing side in sliding contact with the shaft seal member 32 in the valve element side is disposed in the through-hole 13a of the valve casing seat 13. An expanded seal part 31b wider than the seal surface 32a of the shaft seal member 32 in the valve element side is provided in the seal surface 31a of the shaft seal material 31 in the valve casing side having a larger diameter than that of the shaft seal member 32 in the valve element side, a planar surface 24b in sliding contact with the expanded seal part 31b is formed in the valve element seat 24, and the planar surface 24b of the valve element seat 24 and the seal surface 32a of the shaft seal member 32 in the valve element side are formed on a same plane level.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft seal structure of a butterfly valve, and more particularly to a technique for sealing a valve body, a valve box, and a valve stem in a watertight manner. is there. 2. Description of the Related Art Conventional butterfly valves include, for example, FIGS.
There is one as shown in FIG. 5 to 10, the butterfly valve 11 has a cylindrical valve box sheet 13 provided inside a valve box 12 concentrically with the axis of the flow path and with a predetermined gap S therebetween. 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. Between the valve element 22 and the bearing 20, a ring-shaped valve element-side shaft sealing material 25 made of a metal material and a valve box-side shaft sealing material 26 made of rubber elastic material are arranged. The valve body-side shaft seal material 25 is disposed on both sides of the valve body 22 in the axial direction of the valve stem 18, and the valve body sheet 24 is provided between the two valve body-side shaft seal materials 25. The valve body-side shaft seal material 25 is inserted into the recess 22 a of the valve body 22, and the valve box-side shaft seal material 26 is inserted into the through hole 13 a of the valve box sheet 13. 26 and valve body side shaft seal material 2
5 are arranged in contact with each other. An annular pressing plate 27 is arranged on the other end side of the bearing 20, and the pressing plate 27 is attached to the boss 19 with a tightening bolt 28. By tightening the tightening bolt 28, the holding plate 27, the bearing 2
0, the valve-box-side shaft sealing material 26 is pressed against the valve body-side shaft sealing material 25. [0007] By the way, the valve body-side shaft seal material 25, the valve box-side shaft seal material 26, and the valve body sheet 2
4. Valve box sheet 13 on which valve box-side shaft sealing material 26 is arranged
A processing dimension error occurs in the through hole 13a. For this reason, as shown in FIG. 10, a gap A is formed at a portion where the above-mentioned four components face each other. For this reason, the tightening bolt 28 is tightened, and the valve-box-side shaft-sealing seal material 26 is pressed against the valve-body-side shaft-sealing seal material 25 via the holding plate 27 and the bearing 20. Is elastically deformed, and the gap A is eliminated by the overhang. However, when the valve-box-side shaft-sealing material 26 is strongly pressed against the valve-body-side shaft-sealing material 25, the frictional force at the sliding contact surface between the valve-box-side shaft-sealing material 26 and the valve-body-side shaft-sealing material 25 is increased. Becomes large, and hinders the rotational movement of the valve body 22. In addition, the valve box-side shaft sealing material 26 that protrudes into the gap A due to elastic deformation receives the rotational movement of the valve body 22 while being pressed by the edge of the opening peripheral edge of the through hole 13 a of the valve box sheet 13, and is thus damaged. Easier to do. The present invention has been made to solve the above-mentioned problems, and has a structure in which a gap is hardly formed between components in a shaft sealing portion, causes damage to a valve box-side shaft sealing material, and hinders rotational movement of a valve body. It is an object of the present invention to provide a butterfly valve shaft sealing structure that can reduce the number of factors. [0011] In order to solve the above-mentioned problems, a shaft seal structure of a butterfly valve according to the present invention comprises a valve box sheet having a cylindrical shape disposed inside a valve box. A valve rod inserted into a through hole formed in a seat, a valve rod is disposed, a valve element that rotates around the axis of the valve rod is disposed in the valve box sheet, and a valve element that slides on the outer periphery of the valve element and contacts the valve box sheet. A seat is provided, an annular concave portion is formed in the valve body along the circumference of the valve stem, a ring-shaped valve body-side shaft seal material is disposed in the recess, and the valve body-side shaft seal material is slidably contacted with each other on the seal surface. In a butterfly valve in which a ring-shaped valve box-side shaft seal material made of an elastic material is disposed in a through hole of a valve box sheet, the valve box-side shaft seal material is formed to have a larger diameter than the valve body-side shaft seal material. Protrudes radially from the outer periphery of the sealing surface of the valve body side shaft sealing seal material to the sealing surface of the valve box side shaft sealing seal material An extended seal portion is provided, and a flat surface slidably contacting the extended seal portion of the valve box-side shaft seal material is formed on the valve body sheet, and the valve body-side shaft seal seal with respect to the flat surface of the valve body sheet and the valve box-side shaft seal material. The sealing surface of the material is formed on the same plane level. [0012] With the above construction, the valve body-side shaft seal material and the valve box-side shaft seal material seal each other between the end faces in the axial direction at both seal surfaces, and the valve box-side shaft seal material is a seal surface. The seal between the flat surface of the valve body sheet and the inner peripheral surface of the through hole of the valve box sheet is sealed on the outer peripheral surface at the expanded seal portion. Therefore, the outer peripheral edge of the sealing surface of the valve box-side shaft sealing seal material is located outside the outer peripheral edge of the valve body-side shaft sealing seal material by a distance corresponding to the extended seal portion, so that the valve body sheet and the valve body side are sealed. The processing dimension error of the shaft seal material and the processing error of the through hole of the valve box sheet and the valve box side shaft seal material do not overlap at the same position in the radial direction of the valve stem, and a gap is formed between parts in the shaft seal portion. It is a structure that is unlikely to occur, and between the end of the valve body sheet, the outer peripheral edge of the valve body side shaft sealing seal material, the opening peripheral portion of the through hole of the valve box sheet, and the outer peripheral edge of the valve box side shaft sealing seal material as in the past. No gaps are generated. Therefore, there is no need to excessively elastically deform the valve-box-side shaft-sealing material so that the valve-box-side shaft-sealing material needs to be extended into the gap as in the prior art. By keeping the pressing force of the side shaft sealing material at an appropriate value, the rotational movement of the valve body is not hindered, and the cause of damage to the valve box side shaft sealing material can be reduced. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a metal sheet butterfly valve according to an embodiment of the present invention will be described with reference to the drawings. 1 to 4, 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 annular valve box-side seal member 31 made of an elastic material such as rubber has a larger diameter than the annular valve body-side shaft seal member 32 made of a metal material. The sealing surface 31a of the member 31 is a portion that projects radially from the outer periphery of the sealing surface 32a of the valve body-side shaft sealing material 32 as an expanded seal portion 31b. The sealing surface 31a of the valve box-side shaft seal material 31 is coated with an ethylene tetrafluoride resin coating at a portion inside the extended seal portion 31b to reduce friction with the seal surface 32a of the valve body-side shaft seal material 32. 3
1c is provided. The valve sheet 24 is made of a valve-box-side shaft sealing material 31.
Has a flat surface 24b at a position where it comes into sliding contact with the extended seal portion 31b. The flat surface 24b of the valve body sheet 24 and the sealing surface 32a of the valve body-side shaft sealing seal material 32 with respect to the valve box-side shaft sealing seal material 31 are formed. They are formed on the same plane level. The flat surface 24b of the valve body sheet 24 and the sealing surface 32a of the valve body-side shaft sealing material 32 are processed as shown in FIG. That is, in a state where the valve body-side shaft sealing material 32 is welded and fixed to the concave portion 22a of the valve body 22, the sealing surface 32a of the valve body-side shaft sealing material 32 has a distance β larger than the distance α that protrudes from the valve body sheet 24. The valve body sheet 24 and the valve body-side shaft sealing material 32 are simultaneously ground by machining. The operation of the above configuration will be described below. The valve-box-side shaft-sealing seal material 31 slides against the sealing surface 32a of the valve-body-side shaft-sealing seal material 32 at the coating portion 31c of the sealing surface 31a, thereby sealing both end faces in the axial direction with each other. The valve seat 2 in the portion 31b
4 and a seal between the outer peripheral surface and the inner peripheral surface of the through hole 13a of the valve box sheet 13. Therefore, the outer peripheral edge of the sealing surface 31a of the valve-box-side shaft-sealing seal material 31 is located outside the outer peripheral edge of the valve-body-side shaft-sealing seal material 32 by a distance corresponding to the extended seal portion 31b, so that the valve body Of the recess 22 a of the valve body 22 and the valve body-side shaft sealing material 32 and the through hole 13 of the valve box sheet 13
a and the processing error of the valve box side shaft seal material 31
8 does not overlap at the same place in the radial direction, and a structure in which a gap is hardly generated between components in the shaft sealing portion. Therefore, as in the prior art, the valve body sheet 24
No gap is generated between the end of the valve body, the outer peripheral edge of the valve body-side shaft sealing seal material 32, the opening peripheral portion of the through hole 13 a of the valve box sheet 13, and the outer peripheral edge of the valve box side shaft sealing seal material 31. There is no need to excessively elastically deform the box-side shaft-sealing seal material 31 to project the valve-box-side shaft seal material 31 into the gap. As described above, according to the present invention, an extended seal portion having a diameter larger than the outer peripheral edge of the valve body-side shaft seal is formed on the seal surface of the valve box-side shaft seal. By forming a flat surface in sliding contact with the expanded seal portion on the body sheet, it is necessary to excessively elastically deform the valve-box-side shaft-sealing material as in the related art, and project the valve-box-side shaft-sealing material into the gap. By keeping the pressing force of the valve box-side shaft seal material against the valve body-side shaft seal material at an appropriate value, the rotational motion of the valve body is not hindered and the valve box-side shaft seal material is damaged. Can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a main part showing a metal sheet butterfly valve according to an embodiment of the present invention. FIG. 2 is a plan view showing a valve body of the metal seat butterfly valve. FIG. 3 is an explanatory view showing a method for processing a valve body sheet of the metal sheet butterfly valve. FIG. 4 is an enlarged view showing a main part 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 of a main part of the metal seat butterfly valve. FIG. 8 is a sectional view showing a valve body of the metal seat butterfly valve. FIG. 9 is a plan view showing a valve body of the metal seat butterfly valve. FIG. 10 is an enlarged view showing a main part of the metal seat butterfly valve. DESCRIPTION OF SYMBOLS 11 Metal sheet butterfly valve 12 Valve box 13 Valve box sheet 13a Through hole 18 Valve rod 20 Bearing 22 Valve element 24 Valve element sheet 24b Flat surface 27 Press plate 28 Tightening bolt 31 Valve box shaft seal material 31a Seal surface 31b Expansion seal portion 31c Coating portion 32 Valve body side shaft seal material 32a Seal surface

Claims (1)

Claims 1. A cylindrical valve box sheet is disposed inside a valve box, and a valve stem is inserted into a through hole formed in the valve box sheet, and a valve stem is disposed therein. A valve body that rotates around the axis of the valve stem is disposed on the valve body, and a valve body sheet that slides on the valve box sheet is provided on the outer periphery of the valve body. A ring-shaped valve body-side shaft-sealing seal material is disposed in the recess, and a ring-shaped valve-box-side shaft-sealing seal material made of an elastic material that slides on the valve body-side shaft-sealing seal material mutually at the sealing surface. In the butterfly valve arranged in the above, the valve box side shaft sealing seal material is formed larger in diameter than the valve body side shaft sealing seal material, and the sealing surface of the valve body side shaft sealing seal material is An extended seal that protrudes radially from the outer circumference is provided, and the flat surface that slides into contact with the extended seal of the valve-side shaft seal A shaft sealing portion structure for a butterfly valve, wherein a flat surface of the valve body sheet and a sealing surface of the valve body side shaft sealing seal material with respect to the valve box side shaft sealing seal material are formed on the same plane level. .