JPH0921481A - Shaft seal device for butterfly valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure prescribed sealing performance and surely prevent leakage between a valve rod and a shaft seal member without affected by an inclined attitude of the valve rod. SOLUTION: A ring projecting part 20d pressed against an outer circumferential face of a valve rod 4 is integrally formed in an internal circumferential face of a ring elastic seal material 20 in a shaft seal member 11 pressurizing inward in the axial direction by a presser cylinder 12 which is fittedly held in a bearing cylinder by letting the valve rod 4 to fit outwardly and at the same time an axial internal end face 20e of the elastic seal material 20 is constituted on such a slope face that its axial thickness is gradually increased as approaching to the diametrically internal direction but is flattened in the incorporated state.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a shaft sealing device for a butterfly valve.

[0002]

2. Description of the Related Art Heretofore, as a shaft seal device of this type, one having a structure as shown in, for example, Japanese Utility Model Publication No. 55-50439 is known. As shown in FIG. 5, an annular shaft sealing member 103 is supported in a bearing cylinder 102 of a cylindrical valve box 101, and a valve rod 104 supported by the bearing cylinder 102.
To the outer circumference of the bearing cylinder 102, and a retaining cylinder 105 for the shaft sealing member 103 is externally fitted to the valve rod 104 in the bearing cylinder 102 and screwed to the axially outer end side of the bearing cylinder 102. A bolt 106 that is inserted to displace the pressing cylinder 105 inward in the axial direction is provided. The bearing member 103 includes a metal ring 107 fitted on the valve rod 104 and an annular elastic seal member 108 fitted on the metal ring 107.
Reference numeral 8 is composed of an axially inner end surface of the metal ring 107, that is, a base portion 108a that covers the surface facing the valve body boss portion 109 and a peripheral wall portion 108b that covers the outer peripheral surface of the metal ring 107. .

In the shaft sealing device having the above structure, the bolt 10
When 6 is screwed in and the pressing cylinder 105 is tightened, the pressing cylinder 105 causes the shaft sealing member 103 to move to the valve body boss portion 109.
Since it is pressed to the side, the base portion 108 of the elastic seal material 108 is
While a is pressed against the valve body boss portion 109 to seal this portion, the peripheral wall portion 108b of the elastic seal material 108 is elastically compressed and pressed against the inner peripheral surface of the bearing tube 102, and this portion is It is sealed, and the inner peripheral surface of the base portion 108a of the elastic seal member 108 is also in pressure contact with the outer periphery of the valve rod 104.

[0004]

In the conventional butterfly valve shaft sealing device having the above-described structure, the base portion 108a of the elastic sealing material 108 in the shaft sealing member 103 holds the holding cylinder 105.
Since it is only pressed against the valve body boss portion 109 while being flat as a result of the pressing force of, the tilting of the mounting posture of the valve body (not shown) will be affected and the sealing performance will be affected. The pressure contact force is relatively small because the inner peripheral surface of the elastic seal material 108 only comes into surface contact with the outer peripheral surface of the valve rod 104. Therefore, the shaft sealing member 103 and the valve rod 104 are not in contact with each other. There is a risk that leakage may occur between the gaps, and the sealing function was not sufficient.

The present invention has been made in view of the above circumstances, and it is possible to exert a high sealing performance without being affected by the inclination of the valve body and the like, and to prevent leakage between the shaft sealing member and the valve rod. It is an object of the present invention to provide a shaft sealing device for a butterfly valve that can surely prevent the above.

[0006]

In order to achieve the above object, a shaft sealing device for a butterfly valve according to the present invention is fitted onto a valve rod supported by a bearing cylinder of a valve shaft so as to fit inside the bearing cylinder. The ring-shaped shaft sealing member that is fitted and held, and the valve rod boss side on the valve body boss side by being externally fitted to the valve rod and fitted into the bearing cylinder and receiving a tightening force inward in the axial direction. A ring made of metal, which is fitted onto the valve rod, and the axial sealing inner end face and outer peripheral face of the metal ring. In a shaft sealing device for a butterfly valve, which is composed of an annular elastic seal member fitted to the inner peripheral surface of the elastic seal member, an annular protrusion that is in pressure contact with the outer peripheral surface of the valve rod is integrally formed. In addition, as the axially inner end surface of this elastic seal material reaches its inner peripheral side, Increasing the thickness of the axial gradually, and those which are formed on the inclined surface being planarized in assembled state.

According to the present invention, when the push cylinder is tightened inward in the axial direction, the ring-shaped shaft seal member is pressed by the push cylinder toward the valve body boss portion, and the elastic seal material of the shaft seal member is elastic. Compressed. At this time, since the annular projection is integrally formed on the inner peripheral surface of the base portion of the elastic seal material, the inner peripheral surface of the elastic seal material makes line contact with the outer peripheral surface of the valve rod. On the other hand, since the axial inner end surface of the base portion of the elastic seal member is formed as an inclined surface whose thickness in the axial direction gradually increases as it goes radially inward, the pushing cylinder and the valve body boss portion Due to the large elastic reaction force when compressed between the two, the pressure contact force against the valve body boss increases and even if the valve body tilts,
It is possible to secure good sealing performance at this portion. Further, since the base portion of the elastic seal member is compressed to bulge the protrusion, a large pressure contact force can be obtained even with respect to the outer peripheral surface of the valve shaft, so that the space between the valve shaft and the shaft sealing member is increased. It is possible to effectively prevent the leakage of

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical cross-sectional front view showing a butterfly valve to which a shaft sealing device according to an embodiment of the present invention is applied.

In FIG. 1, reference numeral 1 is a cylindrical valve box, and 2 is a disk-shaped valve body disposed in the valve box 1. Above valve box 1
Bearing cylinders 3, 3 that communicate with the inside of the valve box 1 are formed in the upper and lower portions of the valve box 1. The upper and lower bearing cylinders 3, 3 are connected to the upper and lower portions of the valve body 2. The valve rods 4 and 4 are respectively supported. The upper valve rod 4 projects above the bearing sleeve 3 and is rotationally driven by, for example, a deceleration rotation drive mechanism (not shown). Shaft sealing devices 5 and 5 are provided at the bearing portions of the upper and lower valve rods 4 and 4, respectively. Since the upper and lower shaft sealing devices 5 and 5 have the same configuration, the upper shaft sealing device 5 will be described as a representative in FIG.

In FIG. 2, reference numeral 11 denotes an annular shaft sealing member, which is fitted and held in the bearing cylinder 3 by being externally fitted to the valve rod 4. Reference numeral 12 is a holding cylinder for the shaft sealing member 11, and a flange 12a is integrally formed at the outer end in the axial direction, and is fitted into the bearing cylinder 3 by being externally fitted to the valve rod 4. Reference numeral 13 denotes a bush arranged on the inner peripheral surface side of the pressing cylinder 12. The bolt insertion hole 14 formed in the flange 12a of the pressing cylinder 12 is screwed into a screw hole portion 15 formed on the axially outer end surface side of the bearing cylinder 3 to move the pressing cylinder 12 in the axial direction. A bolt 16 for tightening in one direction is inserted. Reference numeral 17 denotes a valve body boss portion formed so as to surround the valve rod 4, and reference numeral 18 denotes a ring fixed to the boss portion 17 so as to be positioned axially outward of the valve body boss portion 17.

As shown in FIGS. 3 and 4, the annular shaft sealing member 11 has a metal ring 19 fitted on the valve rod 4.
And an annular elastic seal member 20 made of rubber or the like fitted to the metal ring 19. The elastic sealing material 20 covers the axially inner end surface of the metal ring 19, that is, the base surface 20 a that covers the surface facing the valve body boss 17.
And a peripheral wall portion 20b which covers the outer peripheral side of the metal ring 19 and slightly protrudes from the outer end of the ring 19 in the axial direction, are integrally formed to have a substantially L-shaped cross section. 20
c is formed on the peripheral wall portion 20b and is formed of the metal ring 1
9 is a locking projection that engages with the engagement recess 19a of the reference numeral 9. On the inner peripheral surface of the base portion 20a of the elastic sealing material 20, an annular protrusion 20d is formed integrally with the outer peripheral surface of the valve rod 4 in pressure contact, and the axial inner end surface 20 of the base portion 20a is formed.
e is configured as a sliding surface for the valve body boss portion 17, and in the state before assembly, as shown in FIG. 4, an inclination such that the thickness in the axial direction gradually increases as it goes inward in the radial direction. Is formed on the surface. The metal ring 19
As shown in FIG. 3, a plurality of axial holes 21 are formed at equal intervals in the circumferential direction on the axial outer end surface of the axial hole 21. The connecting shaft 23 to be fitted is planted.

In FIG. 2, 24 is a V packing interposed between the pressing cylinder 12 and the valve rod 4, 25 is a packing pressing member, and 26 is provided in the pressing cylinder 12 and the packing pressing member 25 is a nut. It is a stud bolt tightened with 27.

In the shaft sealing device having the above structure, the shaft hole 21
After the shaft sealing member 11 having the connecting shaft 23 installed therein is externally fitted to the valve rod 4 in the bearing cylinder 3 and retained therein, the presser cylinder 12 is inserted into the bearing cylinder 3 and the presser cylinder 12 side The shaft hole 22 is fitted into the connecting shaft 23. In this state, the holding cylinder 1
When the bolt 16 on the side of the flange 12a of 2 is screwed in and the holding cylinder 12 is tightened inward in the axial direction, the shaft sealing member 11 is pressed, so that the base portion 2 of the elastic sealing material 20 is pressed.
The inclined surface 20e of the valve body 0a
It is pressed against 7 and is elastically compressed and deformed from the state shown by the chain line in FIG. 3 to be flattened as shown by the solid line in FIG. Since a large pressure contact force acts due to the elastic reaction force at this time, even if the mounting posture of the valve body 2 is inclined, this portion can be reliably sealed. Further, since the peripheral wall portion 20b of the elastic sealing material 20 is axially compressed by the pressing cylinder 12 to become thick, it is strongly pressed against the inner peripheral surface of the bearing cylinder 3, and this portion is also effectively sealed. In particular, the annular protrusion 20 formed on the inner peripheral surface of the base portion 20a of the elastic sealing material 20.
d comes into contact with the outer peripheral surface of the valve rod 4, and the base portion 20
By compressing the sliding surface 20e of a in the assembled state,
This further bulges the protrusion 20d inward in the radial direction. Therefore, a high contact pressure can be obtained with respect to the valve rod 4, and leakage between the outer peripheral surface of the valve rod 4 and the inner peripheral surface of the holding cylinder 12 can be reliably prevented. The cross-sectional shape of the protrusion 20d is not limited to a hemispherical shape, and any shape such as a triangular shape can be selected.

By the way, the protrusion 2 of the elastic sealing material 20
If the inner diameter φd of 0d is equal to or larger than the diameter φD of the valve rod 4, the workability of assembling the elastic seal member 20 is poor, and the protrusion 20d may be damaged. Therefore, if the inner diameter φd is larger than the diameter φD by several mm (about 1 to 1.5 mm), the assembling property is improved and the protrusion 20d is prevented from being damaged. In this case, the effect of the protrusion 20d being pressed against the outer peripheral surface of the valve rod 4 is sufficiently exerted by increasing the tightening force for the shaft sealing member 11.

[0015]

As described above, according to the present invention, the inner peripheral surface of the elastic seal member of the annular shaft sealing member which is externally fitted to the valve rod and held in the bearing cylinder is pressed against the valve rod. Forming an annular protrusion, and the thickness of the elastic sealing member gradually increases in the axial direction as the axial inner end surface of the base portion of the elastic sealing member faces radially inward, and the inclined surface is flattened in the assembled state. Since it is formed in the above-mentioned manner, it is possible to exhibit excellent sealing performance with the valve body boss portion regardless of the inclination of the valve body. In addition, the sealing performance between the outer peripheral surface of the valve rod and the inner peripheral surface of the holding cylinder is improved, and leakage at this portion can be reliably prevented.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing a butterfly valve to which a shaft sealing device according to an embodiment of the present invention is applied.

FIG. 2 is a vertical sectional front view showing the shaft sealing device according to the embodiment.

FIG. 3 is a half-longitudinal sectional front view showing a shaft sealing member in the coaxial sealing device in an assembled state.

FIG. 4 is a half-vertical front view showing the coaxial sealing member in a state before assembly.

FIG. 5 is a vertical cross-sectional front view showing a conventional shaft sealing device for a butterfly valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Valve box 3 Bearing cylinder 4 Valve rod 11 Shaft sealing member 12 Holding cylinder 17 Valve body boss part 19 Metal ring 20 Elastic seal material 20d Annular protrusion 20e Sloping surface

Claims (1)

[Claims] 1. An annular shaft sealing member externally fitted to a valve rod supported by a bearing cylinder of a valve shaft and fitted and held in the bearing cylinder, and externally fitted to the valve rod in the bearing cylinder. A press-fitting cylinder that presses the shaft-sealing member toward the valve body boss when receiving a tightening force inward in the axial direction, and the shaft-sealing member is externally fitted to the valve rod. In a shaft sealing device for a butterfly valve, which is composed of a metal ring and an annular elastic seal member fitted to the ring in a state of covering the inner end surface and the outer peripheral surface in the axial direction of the metal ring, An annular protrusion that is in pressure contact with the outer peripheral surface of the valve rod is integrally formed on the inner peripheral surface of the elastic seal member, and the axial inner end surface of the elastic seal member extends in the axial direction as it reaches the inner peripheral side. It is formed on an inclined surface whose thickness gradually increases and is flattened in the assembled state. Shaft sealing device of the butterfly valve according to claim.