JP2001221346A - Shaft seal structure of buttery valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shaft seal structure of a butterfly valve capable of shortening a distance (a moment arm) of the moment acting on a valve rod and reducing the number of part items. SOLUTION: In this shaft seal structure of the butterfly valve where the valve rod 4a is inserted into a valve element boss part 6 to connect and fix a valve element 3 to the valve rod 4a, a bearing member 9 is fitted and fixed to an installing boss 8 arranged outside a valve casing 2 and the valve rod 4a is inserted into a bearing member 9, an inner end part of the bearing member 9 enters the valve casing 2. A ring-shaped thin plate 14 slidably contacting with an end surface of the valve element boss part 6 is installed on an inner end surface of the bearing member 9. An outer peripheral surface of the inner end part of the bearing member 9 is covered with a rubber member 17 brought into close contact with an inner peripheral surface of a hole part 16 penetrating into the valve casing 2 from the installing boss 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft sealing structure for a butterfly valve.

[0002]

2. Description of the Related Art Conventionally, as a butterfly valve of this kind,
For example, as shown in FIG. 5, a cylindrical valve body boss portion 32 is integrally provided at the center of a disc-shaped valve body 31, and the valve body boss portion 32 has an upper valve stem 33 a and a lower valve stem 33. 33b are inserted respectively, and the valve element 31 and both valve rods 33a, 33 are inserted.
and b are integrally connected and fixed. Note that a rubber lining 35 is provided inside the valve box 34.

[0003] The shaft sealing structure of the upper valve stem 33a is configured as follows. That is, as shown in FIG. 6, a cylindrical mounting boss 36 is provided outside the upper part of the valve box 34, and the mounting boss 36 has a cylindrical bearing member 37.
Are fixed to the mounting boss 36 with bolts 38. The upper valve stem 33a is inserted through the bearing member 37, whereby the upper valve stem 33a is rotatably held by the valve box. A thin cylindrical bush 49 is interposed between the inner end (lower end) of the bearing member 37 and the upper valve rod 33a. Further, at the outer end of the bearing member 37, a packing 39 for sealing and a packing presser 40 are provided.
And are attached.

The inner end face of the bearing member 37 and the upper end face of the valve body boss 32 are opposed to each other in the axial direction of the upper valve rod 33a. A ring 41 is integrally fixed via a pin 42. Further, a valve body side ring 43 is integrally fixed to the upper end surface of the valve body boss portion 32 via a pin 44. The bearing ring 41 is provided with a projection 45 that is in sliding contact with the valve body ring 43 over the entire circumference. The outer peripheral surface of the bearing-side ring 41 is in close contact with the inner peripheral surface of a valve stem insertion hole 46 formed in the upper part of the valve box 34.

[0005] As shown in FIG. 7, a lower valve stem 33b is provided.
Is the same as the above-described shaft sealing structure of the upper valve stem 33a. According to this, both valve stems 33
When the valve body 31 is opened and closed by rotating the shafts a and 33b around the axis, the valve body side ring 43 also rotates together with the valve rods 33a and 33b and the valve body 31. 45 slide contact. The fluid in the valve box 34 is separated from the valve body-side ring 43 by
And the projection 45 of the bearing-side ring 41, it is prevented from entering between the valve rods 33a, 33b and the bearing member 37. Furthermore, the fluid in the valve box 34 is sealed by the outer peripheral surface of the bearing-side ring 41 and the inner peripheral surface of the valve rod insertion hole 46 that are in close contact with each other, so that the fluid enters between the bearing member 37 and the mounting boss 36. Is prevented.

As shown in FIGS. 6 and 7, a force in a direction perpendicular to the axis acts on the end position A of the valve body boss portion 32 by the fluid, and the fluid acts on both valve rods 33a and 33b, respectively. A moment is generated. The moment is defined as a fulcrum at a position B which is a fixed distance from the inner end of the bearing member 37 (generally, a distance of H / 3 from the inner end of the bearing member 37 when the entire length of the bush 49 is H). The distance from the position A to the position B is defined as a moment distance L (moment arm).

In the shaft sealing structure, the valve body side ring 4
3 and the bearing-side ring 41, there is a problem that the number of parts increases, and another shaft sealing structure has been proposed to solve this problem.

That is, as shown in FIG. 8, a bearing ring 41 is attached and fixed to an inner end face of a bearing member 37, and a projection 45 of the bearing ring 41 slides on an end face 47 of a valve body boss 32. It is configured to touch. According to this, the valve body side ring 43 shown in FIG.
The number of parts is reduced. In opening and closing the valve element 31 by rotating the valve rods 33a and 33b around the axis, the valve element boss 3
The second end surface 47 is in sliding contact with the projection 45 of the bearing-side ring 41. The fluid in the valve box 34 is sealed by the end surface 47 of the valve body boss 32 and the projection 45 of the bearing ring 41, which are in sliding contact with each other, so that the fluid enters between the valve rods 33 a and 33 b and the bearing member 37. Is prevented. further,
The fluid in the valve box 34 is transferred to the bearing-side ring 41
And the inner peripheral surface of the valve stem insertion hole 46, it is prevented from entering between the bearing member 37 and the mounting boss 36.

[0009]

In the conventional shaft sealing structure shown in FIGS. 6 and 7, the two rings 41, 43 are provided between the inner end face of the bearing member 37 and the end face of the valve body boss portion 32. Is inserted, the interval S in the axial direction between the inner end surface of the bearing member 37 and the end surface of the valve body boss portion 32 increases. When the distance S increases, the position B moves outward by that amount, so that the distance L (moment arm) of the moment increases and the moment increases. As a result, at the position B, the valve rods 33a, 33a,
The stress acting on the shaft 33b may increase, and the strength of each of the valve rods 33a and 33b with respect to the moment may be reduced.

Further, in the other conventional shaft sealing structure shown in FIG. 8, the valve body side ring 43 is not required. However, as shown in FIG. 47 slightly protrudes outside the outer peripheral edge of the valve body 31. For this reason, when performing sheet processing on the outer peripheral edge of the valve element 31, there is a problem that the end face 47 of the valve element boss portion 32 hinders turning processing.
Further, similarly to the conventional shaft sealing structure shown in FIGS. 6 and 7, the strength of each of the valve stems 33a and 33b with respect to the moment may be reduced.

According to the present invention, there is provided a butterfly valve capable of shortening the distance of a moment acting on a valve stem (moment arm), further reducing the number of parts, and enabling the outer peripheral edge of a valve body to be turned. An object is to provide a shaft sealing structure.

[0012]

According to a first aspect of the present invention, a valve stem is inserted into a cylindrical valve body boss portion provided integrally with a valve body so that the valve body is connected to the valve body. By connecting and fixing a rod, a cylindrical bearing member is fitted into and fixed to a cylindrical mounting boss provided on the outside of the valve box, and the valve rod is inserted into the bearing member so that the valve rod is a valve. A shaft sealing structure of a butterfly valve rotatably held in a box, wherein a distal end of the bearing member enters the inside of a valve box, and a distal end surface of the bearing member includes a valve body in a rotation direction of a valve stem. A ring-shaped thin plate that is slidable on the end surface of the boss portion is attached, and an outer peripheral surface of a tip portion of the bearing member is in close contact with an inner peripheral surface of a hole portion that penetrates into the valve box from the mounting boss. It is covered with.

According to this, when the valve stem is rotated about the axis to open and close the valve body, the end face of the valve body boss portion comes into sliding contact with the thin plate. Since the fluid in the valve box is sealed by the end face of the valve body boss portion and the thin plate which are in sliding contact with each other, it is prevented from entering between the valve rod and the bearing member. further,
The fluid in the valve box is sealed by the elastic member and the inner peripheral surface of the hole that are in close contact with each other, so that the fluid is prevented from entering between the bearing member and the mounting boss.

Further, since the thin plate is sandwiched between the distal end surface of the bearing member and the end surface of the valve body boss portion as described above, and the distal end portion of the bearing member is inserted into the inside of the valve box, the valve is closed. The distance of the moment acting on the rod (moment arm) is shortened, whereby the above-mentioned moment is reduced, so that the strength of the valve rod with respect to the moment is improved.

Further, the number of parts can be reduced as compared with the conventional case where two types of rings are used. In the second invention, the end face of the valve body boss is recessed inward from the outer peripheral edge of the valve body in the axial direction of the valve stem.

According to this, when the outer peripheral edge of the valve element is subjected to sheet processing, the end face of the valve element boss does not hinder the turning operation, so that the outer peripheral edge of the valve element can be processed by the turning operation. Become.

[0017]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described with reference to FIG. As shown in FIG. 4, reference numeral 1 denotes a butterfly valve, which is mainly composed of a valve box 2, a valve body 3, a pair of upper and lower valve rods 4 a, 4 b, and a valve element 3 formed by rotating the valve rods 4 a, 4 b. And a drive device 19 that opens and closes.
A rubber lining 5 is provided inside the valve box 2. A cylindrical valve body boss 6 is integrally provided at the center of the disc-shaped valve body 3. In addition, as shown in FIG.
The upper and lower end faces 7 of the valve body boss 6 are recessed inward from the outer peripheral edge of the valve body 3. A rubber lining (not shown) is provided on the outer surface of the valve body boss portion 6.

The inner end of the upper valve stem 4a is inserted into the upper part of the valve body boss 6, and is connected and fixed by bolts (not shown) or the like. Similarly, the inner end of the lower valve stem 4b is inserted into the lower portion of the valve body boss 6, and is connected and fixed by bolts (not shown) or the like.

The shaft sealing structure of the upper valve stem 4a is configured as follows. That is, as shown in FIG. 1, a cylindrical mounting boss 8 is integrally provided on the upper outer side of the valve box 2, and a hole 16 penetrating from the upper end of the mounting boss 8 to the upper inner side of the valve box 2 is formed. Is formed. A cylindrical bearing member 9 is fitted into the mounting boss 8, and is fixed to the mounting boss 8 with a plurality of bolts 10. The bearing member 9
The upper valve stem 4 a is inserted through the valve stem 2, whereby the upper valve stem 4 a is rotatably held by the valve box 2. A thin cylindrical bush 13 is interposed between the inner end (lower end) of the bearing member 9 and the upper valve stem 4a. Further, a packing 11 for sealing and a packing presser 12 are attached to the outer end of the bearing member 9.

The inner end of the bearing member 9 enters the inside of the valve box 2 and faces the upper end of the valve body boss 6. A ring-shaped thin plate 14 slidably contacting the upper end surface 7 of the valve body boss 6 in the rotation direction of the upper valve rod 4 a is mounted and fixed to the inner end surface of the bearing member 9 by a plurality of screws 15. I have. The thin plate 14 is made of a material having a low coefficient of friction (such as a fluororesin).

The outer peripheral surface of the inner end of the bearing member 9 is covered (lined) with a rubber member 17 (an example of an elastic member) which is in close contact with the inner peripheral surface of the hole 16. still,
As shown in FIG. 2, the shaft sealing structure of the lower valve stem 4b is the same as the shaft sealing structure of the upper valve stem 4a described above.

The operation of the above configuration will be described below. When the drive device 19 is driven to rotate the two valve rods 4a and 4b to open and close the valve body 3, as shown in FIGS.
The upper and lower end surfaces 7 of the valve body boss 6 are in sliding contact with the thin plate 14, respectively. The fluid in the valve box 2 is sealed by the end face 7 of the valve body boss 6 and the thin plate 14 which are in sliding contact with each other as described above, so that the fluid intrudes between the valve rods 4a and 4b and the bearing member 9. Is prevented. Further, the fluid in the valve box 2 is
Since the rubber member 17 and the inner peripheral surface of the hole 16 which are in close contact with each other are sealed, it is possible to prevent the rubber member 17 from entering between the bearing member 9 and the mounting boss 8.

As shown in FIGS. 1 and 2, a force in the direction perpendicular to the axis acts on the end position A of the valve body boss portion 6 by the fluid, and the fluid is applied to both valve rods 4a and 4b, respectively. Moment acts. This moment is defined as a fulcrum at a position B which is a fixed distance from the inner end of the bearing member 9 (generally, a distance of H / 3 from the inner end of the bearing member 9 when the entire length of the bush 13 is H). The distance from A to the position B is defined as a moment distance L (moment arm).

Here, as described above, the thin plate 14 is sandwiched between the inner end surface of the bearing member 9 and the end surface 7 of the valve body boss portion 6 to seal the inner end portion of the bearing member 9 inside the valve box 2. , The distance S in the axial direction between the inner end surface of the bearing member 9 and the end surface 7 of the valve body boss portion 6 is reduced as compared with the related art, and the position B is shifted inward by the reduced amount. (Position A side), whereby the distance L (moment arm) of the moment acting on the upper valve stem 4a becomes shorter than before. Therefore, since the above-mentioned moment is reduced, the strength of the upper valve stem 4a with respect to the moment is relatively improved. The same effect can be obtained for the lower valve stem 4b.

Further, the number of parts can be reduced as compared with the conventional case using two types of rings. Further, as shown in FIG.
Is recessed inward from the outer peripheral edge of the valve body 3,
When the sheet processing is performed on the outer peripheral edge of the valve body, both end surfaces 7 of the valve body boss portion 6 do not hinder the turning processing.
By turning, the outer peripheral edge of the valve element 3 can be processed.

In the above embodiment, as shown in FIGS. 1 and 2, the thin plate 14 is attached and fixed to the inner end face of the bearing member 9, but instead of providing the thin plate 14, the inner end face of the bearing member 9 is fixed. The bearing member 9 may be coated with a fluororesin to form a fluororesin layer on the inner end surface.

[0027]

As described above, according to the present invention, the distance of the moment acting on the valve stem (moment arm) is shortened, whereby the moment is reduced, and the strength of the valve stem with respect to the moment is improved. Further, the number of parts can be reduced as compared with the case where two types of rings are used as in the related art. Further, the outer peripheral edge of the valve body can be processed by turning.

[Brief description of the drawings]

FIG. 1 is a sectional view of a shaft sealing structure of a valve stem at an upper portion of a butterfly valve according to an embodiment of the present invention.

FIG. 2 is a sectional view of a shaft sealing structure of a valve stem below a butterfly valve.

FIG. 3 is a perspective view of an end of a valve body boss of the butterfly valve.

FIG. 4 is a sectional view showing the overall configuration of the butterfly valve.

FIG. 5 is a cross-sectional view showing the overall configuration of a conventional butterfly valve.

FIG. 6 is a cross-sectional view of a shaft sealing structure of a valve stem at an upper part of a conventional butterfly valve.

FIG. 7 is a cross-sectional view of a shaft sealing structure of a lower valve stem of a conventional butterfly valve.

FIG. 8 is a cross-sectional view of another type of shaft sealing structure in a valve stem above a conventional butterfly valve.

FIG. 9 is a perspective view of an end of a valve body boss of the conventional butterfly valve in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Butterfly valve 2 Valve box 3 Valve body 4a, 4b Valve rod 6 Valve body boss part 7 End face 8 Mounting boss 9 Bearing member 14 Thin plate 16 Hole part 17 Rubber member (elastic member)

Claims (2)

[Claims] [Claim 1] A valve stem is inserted into a cylindrical valve body boss portion provided integrally with a valve body, and the valve body and the valve stem are connected and fixed, and a cylindrical shape provided outside the valve box is provided. A shaft sealing structure of a butterfly valve in which the valve stem is rotatably held in a valve box by fitting and fixing a cylindrical bearing member to the mounting boss, and inserting the valve stem through the bearing member, The distal end of the bearing member enters the inside of the valve box, and a ring-shaped thin plate that is slidably attached to the end surface of the valve body boss portion in the rotation direction of the valve rod is attached to the distal end surface of the bearing member, A shaft sealing structure for a butterfly valve, wherein an outer peripheral surface of a tip portion of the bearing member is covered with an elastic member which is in close contact with an inner peripheral surface of a hole penetrating from the mounting boss into the valve box. 2. The shaft sealing structure for a butterfly valve according to claim 1, wherein an end face of the valve body boss is recessed inward from an outer peripheral edge of the valve body in an axial direction of the valve stem.