JPH0249429Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field The present invention relates to a ball valve that is attached to a fluid piping and used to control the flow of fluid, and in particular, the invention relates to a ball valve that is attached to a fluid piping and used to control the flow of fluid. Regarding the shaft seal structure.

2. Description of the Related Art A conventional valve shaft sealing structure of a ball valve will be described with reference to FIG. This is achieved by forming a flange 53 on the valve shaft 52 that rotates the valve ball 51, arranging several packings 54 on the flange 53, and screwing a holder 55 to the valve casing to compress the packings 54. It spreads in the radial direction and seals.

Problems that the present invention aims to solve In this case, if a leak occurs and the holder is tightened, the packing will be further crushed and spread in the radial direction, and the leak will be stopped, but this will cause unnecessary force on the valve stem. There is a problem in that the shaft torque, that is, the force for rotating the shaft becomes extremely large.

The technical problem of the present invention is to prevent the shaft torque from increasing even if the holder is tightened even if the holder is tightened to prevent leakage from the valve shaft.

Means for Solving the Problems The technical means of the present invention taken to achieve the above technical problem is to insert a valve shaft provided with a flange into a valve casing, and to create a gap between the lower surface of the flange and the valve casing. A disc spring is arranged, a flat packing member is arranged on the upper surface of the flange, a holder is attached thereon, and the inner periphery of the valve casing that contacts the lower outer periphery of the holder or that part is formed into a tapered surface. A packing member having a tapered surface corresponding to the tapered surface described above is arranged.

Further, a plurality of the above-mentioned flat packing members are arranged in the vertical direction.

Effect The operation of the above technical means is as follows.

When the holder screwed to the valve casing is tightened, the reaction force of the disc spring placed on the bottom surface of the valve stem flange presses the flat packing member against the top surface of the valve stem flange, creating a seal with the valve stem surface. . The seal with the valve casing is achieved by a packing member placed between the outer periphery of the lower part of the holder and the valve casing.

When the holder is retightened, the packing member between the lower holder outer circumference and the valve casing is compressed, causing
Close contact due to the wedge effect of the tapered surface. At the same time, the upper part of the flange surface and the packing member thereon are brought into close contact with each other, improving the sealing effect.

As mentioned above, a single flat packing member has a sufficient sealing effect, but by stacking a plurality of flat packing members, the shaft torque is further reduced and wear of the sealing member is suppressed. In other words, with one sheet, the metal and the seal member slide due to high frictional resistance, but with multiple sheets, the holder and the seal member at the top end, and the top surface of the valve shaft flange and the seal member at the bottom end contact and rotate simultaneously, causing the center Since the seal members slide against each other, the frictional resistance is lower than that of the former, so there is less wear and the shaft torque is also reduced.

Effect of invention The present invention produces the following specific effects.

When the packing member between the valve casing and the valve casing is tightened, it compresses and expands in the radial direction, but since there is a holder between the valve shaft and the valve shaft, the valve shaft is not directly compressed. Therefore, no matter how much tightening is done, the shaft torque does not increase, the initial torque can be maintained, and the sealing performance can also be maintained.

At the same time, the packing member is pressed against the upper surface of the flange, but since it is a flat plate, compression has almost no effect on the axial direction. In addition, due to the effect of the disc spring on the lower surface of the flange, even when the holder is tightened, as long as it is within the elastic limit of the disc spring, excessive pressure will not be applied, and there will be no abnormal wear on the packing, resulting in a long life.

Example An example showing a specific example of the above technical means will be described.

First Embodiment (See Figure 1) An end member 2 is attached to a main body 1 to form a valve casing. A valve chamber 3 is formed inside the valve casing, and a valve ball 4 is rotatably arranged. A groove into which the valve shaft 7 is fitted is provided in the upper part of the valve ball 4. Valve seats 5 and 6 are placed between the flow port of the valve ball 4 and the valve casing.
Place.

A valve shaft insertion hole 8 communicating with the valve chamber 3 is provided on the upper side of the main body 1.
will be established. This hole 8 has a tapered surface 10 in the middle, and has an internal thread in the upper part. Insert the valve stem 7 into the hole 8
The valve ball 4 is rotatably inserted into the valve ball 4, and the lower protrusion 9 formed into a single letter is fitted into the upper groove of the valve ball 4.

A flange 11 is formed on the valve shaft 7, and a disc spring 12 is interposed between the lower surface of the flange and the valve casing. Two flat packings 13 are arranged on the top surface, and a holder 15 having an annular protrusion from the top to the bottom is screwed together and pressed. A packing 16 having a tapered surface on the lower outer periphery is interposed on the outside of the holder lower protrusion so that the tapered surface matches the tapered surface 10 of the casing. An O-ring 17 for secondary sealing is arranged inside the protrusion to further prevent leakage on the inside of the shaft.

Second Embodiment (See Figure 2) In Embodiment 1, a tapered surface was formed on the valve casing side, but in this embodiment, a tapered surface 2 was formed on the holder 20 side.
1, and a packing 22 having a tapered surface that fits that surface is interposed between the packing 22 and the casing. Since the other structures are the same as those in FIG. 1, their explanation will be omitted.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the valve stem of a ball valve according to an embodiment of the present invention, Fig. 2 is a sectional view of the valve stem of a ball valve of another embodiment, and Fig. 3 is a sectional view of the valve stem of a conventional ball valve. FIG. 1... Main body, 4... Valve ball, 5, 6... Valve seat, 7... Valve stem, 12... Belleville spring, 13... Flat packing, 15... Holder, 16, 22...
...Packaging member.

Claims (1)

[Claims for Utility Model Registration] 1. A valve shaft provided with a flange is inserted into a valve casing, a disc spring is arranged between the lower surface of the flange and the valve casing, a flat packing member is arranged on the upper surface of the flange, A ball valve in which a holder is mounted on the holder, the inner periphery of the valve casing that contacts the lower outer periphery of the holder or that part is formed into a tapered surface, and a packing member having a tapered surface corresponding to the tapered surface is arranged between them. Valve shaft sealing structure. 2. A valve shaft sealing structure for a ball valve according to claim 1 of the utility model registration, in which a plurality of flat packing members on the upper surface of the valve shaft flange are arranged in the vertical direction.