JPH056456Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] This invention is installed in valves, pumps, etc. that have a shaft that moves reciprocally or rotates, and prevents fluid leakage by an elastic sealing member around the shaft. This relates to a sealing device for a shaft body that shuts off.

[Conventional technology]

The bonnets of valves, pumps, etc. that have a shaft that moves reciprocatingly or rotationally by being driven by a motor or air pressure have a plurality of elastic seal members that are arranged closely in the axial direction around the shaft. , and a packing box for housing the sealing device, which is designed to prevent fluid from leaking to the outside. Asbestos-based or graphite-based packing is generally used as the sealing member provided in this sealing device, and these are compressed by bolting the packing follower fitted to the open end of the packing box to the bonnet. Fixed.

If this batkin is used for a long period of time, the sealing performance will deteriorate due to the stress relaxation of the packing itself, and the fluid will leak to the outside. Therefore, it is necessary to tighten the port that fixes the packing follower and retighten the packing. It is being done.

However, in this retightening method, the force is not applied uniformly to the entire seal, and the seal close to the bolt is tightened well, but the surface pressure applied to the seal decreases as it goes deeper. .

For example, as disclosed in Japanese Patent Application Laid-Open No. 59-180184, a pair of rings with tapered surfaces facing each other is inserted into the middle part of the packing group, and these rings are engaged with the rack and pinion. A retightening mechanism has been proposed in which the packing is compressed by rotating both rings in the opposite direction and moving the rings apart due to the action of the tapered surfaces.

[The problem that the idea aims to solve]

However, since the retightening mechanism in such conventional shaft body sealing devices uses a rack and pinion as described above, when the fluid pressure is high, the gear diameter increases when trying to overcome the resulting frictional force. The problem was that it was so large that it could not be incorporated into the bonnet and could not be put to practical use.

[Means to solve the problem]

In order to solve these problems, this invention
In the middle of a group of elastic seal members closely arranged in a packing box, there is a pair of seal parts having seal members on the inner and outer diameters, and an annular space between these seal parts and communicating with each other on the inner and outer diameters. A stepped ring consisting of a section is divided in the axial direction and slidably inserted, and a through hole connected to an external pressurizing device is provided in the bonnet with the open end facing the annular space on the outer side. Established.

[Effect]

If fluid leaks due to long-term use, etc., by connecting a pressurizing device to the communication hole in the bonnet and activating it, the pressurized fluid will be delivered to the inner and outer annular spaces provided in the pressurizing part of the stepped ring. The divided pieces of the stepped ring that are divided in the axial direction move up and down to separate them from each other, so the upper and lower packing groups are compressed and retightened with equal force, preventing fluid leakage. Be cut off.

〔Example〕

Figures 1 to 3 show an example in which the shaft sealing device according to the present invention is applied to a valve, and Figure 1 is a longitudinal cross-section of the bonnet of the valve in which the shaft sealing device according to the present invention is applied, with a pressurizing device connected. FIG. 2 is an enlarged vertical sectional view of the vicinity of the ring, and FIG. 3 is a perspective view of the ring. In the figure, a bonnet 2 of a valve 1 is provided with a packing box 3 formed in the shape of a circular hole in the center, and an actuator (not shown) is installed in the center of the packing box 3 at its upper and lower ends. A valve drive shaft 4 connected to the valve body and the valve body is provided so as to be vertically movable therethrough. This valve drive shaft 4
Around the periphery of the packing box 3, a plurality of sealing members 5 formed in an annular shape made of an elastic material are inserted in close contact with each other vertically. A packing follower 6 is fitted in a slidable manner. This packing follower 6 is fixed to the bonnet 2 so as to be adjustable forwards and backwards by a bolt 7 screwed into a screw hole of the bonnet 2 and a nut 8 screwed into the threaded portion of the bolt 7. A compression coil spring 9 for biasing the packing 5 upward is interposed between the bottom surface of the packing box 3 and the bottom surface of the packing box 3 via a spring receiver 10. By doing this, the packing 5 is compressed and fixed by the packing follower 6 and the compression coil spring 9.

In this device, a ring 11 is inserted into the middle part of the packing 5. ring 11
is divided into an upper ring 12 and a lower ring 13 in the axial direction, and each of these upper and lower rings 12, 1
3 is integrally formed with large-diameter seal portions 12a, 13a and small-diameter pressurizing portions 12b, 13b protruding from the end faces thereof, and the upper and lower pressurizing portions 12b, 13b
are pressed together at their end faces. Seal part 12a,
O-rings 14 and 15 as sealing members are inserted into the annular grooves provided on the outer and inner diameters of the pressure parts 12b and 13b. Annular spaces 16 and 17 are formed which are communicated with each other through holes 12c and 13c.

The bonnet 2 has both open ends connected to the outer diameter side annular space 16 and a screw hole 1 on the outer periphery of the bonnet 2.
A communication hole 19 is provided facing the screw hole 18 , and a pressurizing device, generally designated by the reference numeral 20 , is connected to the screw hole 18 by screwing the threaded portion of the feed pipe 21 . This pressurizing device 20 includes a pressurizing tube 22 to which the threaded portion of the other end of the feeding tube 21 is screwed together, a pressurizing screw 23 screwed into the screw hole of the pressurizing tube 22, and a pressurizing screw 23 screwed into the screw hole of the pressurizing tube 22. Stop valve 26 with handle 25 sliding within threaded bonnet 24
The pressurized air is supplied to the annular spaces 16 and 17.
By feeding the upper and lower rings 12, 13
The upper and lower gaskets 5 are compressed by moving the gaskets 5 away from each other.

The operation of the sealing device configured as above will be explained. The valve drive shaft 4 is activated by the operation of the actuator.
When the valve is moved forward and backward, a valve body attached to the lower end of the valve drive shaft 4 opens and closes, and the flow rate of the fluid is controlled. The gasket 5 is compressed by a compression coil spring 9, and fluid leakage is blocked by the gasket 5 and O-rings 14 and 15.

If fluid leaks due to stress relaxation or damage to the packing 5 due to long-term use, etc., open the stop valve 26 of the pressurizing device 20 and feed pressurized air with the pressure feeding screw 23. This pressurized air will flow through the communication hole 19. Since the air is then introduced into the annular space 16 and the annular space 17 communicated through the holes 12c and 13c, the air pressure causes the upper ring 12 to move upward and the lower ring 13 to move downward. That is, the upper and lower gaskets 5 are compressed with uniform surface pressure, ensuring sealing performance.

FIG. 4 is a longitudinal cross-sectional view of the vicinity of the ring showing another embodiment of the present invention. In this embodiment, the ring 30 includes an upper ring 31, a lower ring 32, and the space between Color 33
The collar 33 is welded to the lower ring 32. The rings 31 and 32 are provided with O-rings 34 and 35, and the collar 33 is provided with a hole 36 and annular spaces 37 and 38, as in the previous embodiment. With this configuration, the annular space 37,
When pressurized air is supplied to 38, the upper ring 31 moves upward, and the lower ring 32 and collar 33 move downward. Therefore, the upper and lower packing 5
is compressed with uniform surface pressure.

In each of the above embodiments, a pressure feeding screw type pressurizing device is illustrated as an example of the pressurizing device, but the communication hole 19 and a pressure cylinder filled with air may be connected by a pipe provided with a stop valve. In addition, as the fluid to be sent by the pressurizing device, air as in the example or water is easily available and easy to handle, but high viscosity fluids such as oil and grease have stronger lingering properties. , the effect is long-lasting.

[Effects of the Invention] As is clear from the above explanation, in the shaft sealing device according to the present invention, a pair of elastic sealing members having sealing members on the inner and outer diameters are provided at the intermediate portion of the group of elastic sealing members closely arranged in the packing box. A stepped ring consisting of a sealing part and a pressure part having an annular space between the sealing parts and communicating with each other on the inner and outer diameters is divided into parts in the axial direction and is slidably inserted. By providing a communication hole in the bonnet with the opening end facing the annular space on the external side and connected to an external pressurizing device, pressurized fluid can be sent into the annular space by the pressurizing device when retightening the seal member. Then, the divided members of the ring move away from each other and compress the upper and lower seal members, so that substantially uniform surface pressure acts on each seal member, improving sealing performance. Further, even if the fluid to be sealed is a high-pressure fluid, there is no need to increase the size of a pressurizing member such as a ring, and it is possible to incorporate it into the inside of the bonnet, which is effective. Furthermore, since seal members are provided on the inner and outer diameters of the ring, fluid will not leak from there even if the ring slides.

[Brief explanation of the drawing]

Figures 1 to 4 show an example in which the shaft sealing device according to the present invention is applied to a valve, and Figure 1 is a longitudinal cross-sectional view showing the bonnet of the valve in which the sealing device of the present invention is applied, with a pressurizing device connected to it. 2 is an enlarged vertical cross-sectional view of the vicinity of the ring, FIG. 3 is a perspective view of the ring, and FIG. 4 is a vertical cross-sectional view of the vicinity of the ring showing another embodiment of the present invention. 2...Bonnet, 3...Patsukin Box,
4... Valve drive shaft, 5... Packing, 11, 30...
... Ring, 12, 31 ... Upper ring, 12a,
13a... Seal part, 12b, 13b... Pressure part, 12c, 13c, 36... Hole, 14, 15,
34, 35...O ring, 16, 17, 37, 3
8... Annular space, 19... Communication hole, 20... Pressure device.

Claims (1)

[Scope of utility model registration request] In a shaft body sealing device in which a plurality of elastic seal members are tightly arranged around a shaft body passing through the center of a packing box of a bonnet, a pair of seal parts each having a seal member on the inner and outer diameters, and a pair of seal parts between these seal parts. A stepped ring consisting of a pressurizing part having an annular space communicating with each other on the inner and outer diameters is formed divided in the axial direction and is slidably inserted into the middle part of the elastic sealing member, and the outer diameter A sealing device for a shaft body, characterized in that the bonnet is provided with a communication hole whose opening end faces the side annular space and is connected to an external pressurizing device.