JPH0449422Y2 - - Google Patents

Description

[Detailed description of the invention] Purpose of the invention (industrial application field) The invention is particularly applicable to valves such as ball valves and butterfly valves that are opened and closed by the rotation of the valve body when the handle is operated. This invention relates to an improvement of a shaft sealing device for a stem.

(Prior art) As a conventional shaft sealing device of this type, for example, the
- There is one shown in Publication No. 5833.

Although not specifically shown in the drawings, in this conventional device, an enlarged-diameter flange is integrally formed on the upper part of the stem connected to the valve body, and an annular-shaped flange is formed on the inner wall of the fitting hole formed in the shaft mounting part of the valve body. A stopper ring is fitted into the groove, and a restricting action of the stopper ring on the upper surface of the enlarged diameter flange prevents the stem from protruding outward from the valve body. A sealing packing material and a disc spring are arranged vertically between the lower surface of the expanded diameter flange of the stem and the corresponding wall of the fitting hole, and the sealing packing material is expanded by the spring pressure of the disc spring. By pressing against the lower surface of the diameter flange,
The stem is configured to be sealed to the fitting hole of the valve body.

(Problem to be solved by the invention) However, in the conventional shaft sealing device, a sealing packing material and a disc spring are arranged on the lower surface of the enlarged diameter flange of the stem, and the spring pressure of the disc spring is simply applied. The configuration in which the packing material is pressed against the lower surface of the enlarged diameter flange is such that even if the lower surface of the enlarged diameter flange is tapered and the packing material is also given a tapered shape that matches the shape, the sealing material cannot be sealed during use. sex may decrease,
Moreover, if used for a long period of time under high temperature and high pressure, the sealing material itself may undergo plastic deformation, or the disc spring may deteriorate, resulting in poor pressure contact between the packing material and the lower surface of the enlarged diameter collar of the stem. This had a major problem in that the sealing performance was significantly reduced.

Structure of the Invention (Means for Solving the Problems) The present invention was developed to effectively solve the problems of the conventional shaft sealing device. A device for sealing a shaft into a fitting hole formed in a shaft mounting portion of a valve body, which is equipped with a retightening gland that is screwed into the upper end opening of the fitting hole, and the bottom surface of the retightening gland is connected to the bottom surface of the retightening gland. A packing material is provided between the upper surface of the expanded diameter collar of the stem, and a disc spring is provided between the lower surface of the expanded diameter collar and the corresponding wall of the fitting hole, so that the spring pressure of the disc spring causes the stem to The enlarged diameter flange portion is biased in the direction of the additional tightening gland and is hermetically sealed with the above-mentioned packing material. Furthermore,
A secondary seal was formed by an O-ring installed between the stem and the gland, and a metal touch between the receiving surface of the shaft mounting part and the step formed on the gland.

(Function) Accordingly, in the present invention, the expanding diameter flange of the stem is urged in the direction of the retightening gland by the spring pressure of the disc spring, and is hermetically sealed with the above-mentioned packing material. The primary sealing of the stem shaft sealing part is performed reliably, and the secondary sealing is achieved by the metal touch between the O-ring installed between the stem and the gland, and the step formed on the receiving surface of the shaft mounting part and the gland. As a result, even if the sealing material itself becomes deformed or the disc spring deteriorates due to long-term use under high temperature and high pressure, the shaft seal of the stem is reliable. The packing material can always be compressed into an ideal seal between the bottom surface of the gland and the top surface of the enlarged diameter flange of the stem.
There is no need to worry about the sealing performance being significantly reduced due to deformation of the packing material itself or deterioration of the disc spring, as was the case in the past.

(Example) Hereinafter, the present invention will be described in detail based on an illustrative example.

The illustrated embodiment is applied to a ball valve, and as shown in FIG. The ball 3 is rotatably disposed, and the ball 3 is supported by a stem 5 that extends through and is supported in the support hole 4 of the valve body 1, and an operating handle is attached to the upper end of the stem 5 via a bolt 6. 7 is fixed.

In this embodiment, when the stem 5 is sealed to the shaft mounting part on the valve body 1 side, the enlarged diameter flange part 8 is integrally formed on the upper part of the stem 5 as in the conventional case. However, the feature is that, as shown in FIGS. 1 and 2, a female screw portion 11 is formed on the inner wall surface on the upper end side of the fitting hole 10 formed in the shaft mounting portion 9, The male thread part 12a of the retightening gland 12 is screwed into the thread part 11, and the center insertion hole 12b is inserted into the thread part 11.
The upper part of the stem 5 is inserted into the upper part of the stem 5, and the retightening gland 12 is attached to the opening at the upper end of the fitting hole 10, and a mountain-shaped cross section is formed between the lower surface of the gland 12 and the upper surface of the enlarged-diameter flange 8. While the packing material 13 is stacked and arranged, a disc spring 15 is provided via a plate 14 between the lower surface of the enlarged diameter collar part 8 and the corresponding wall surface of the fitting hole 10, and the spring pressure of the disc spring 15 A configuration is adopted in which the stem 5 is biased toward the ground 12 and the laminated packing material 13 forms a primary seal.

In addition, in this embodiment, the fitting hole 1 of the shaft mounting part 9
A receiving surface part 16 that is continuous from the female thread part 11 is formed on the inner wall of the gland 12, and a step part 17 that makes surface contact with the receiving surface part 16 is formed on the lower edge of the gland 12, so that the male thread part 12a and the female thread part When the gland 12 is screwed into the fitting hole 10 via the step part 1
7 and the receiving surface portion 16 are metal-touched to seal the surface contact portion, and a recessed groove 18 is formed above the enlarged diameter flange portion 8 of the stem 5, and the recessed groove 18
An O-ring 19 is disposed inside to further seal between the inner circumferential surface of the gland 12 and the outer circumference of the stem 5, thereby achieving a secondary sealing function.

Note that when adopting a configuration in which the packing material 13 is compressed between the lower surface of the gland 12 and the upper surface of the enlarged-diameter flange portion 8, an O-ring is attached to the metal touch surface in the above embodiment, and a secondary It is also possible to perform sealing.

Therefore, in the case of a ball valve equipped with a shaft sealing device having such a configuration, even if fluid pressure is transmitted to the stem 5 and the stem 5 attempts to protrude from the valve body 1, the shaft of the retightening gland 12 is By screwing the fitting part 9 into the fitting hole 10, it is possible to reliably prevent the stem 5 from popping out.

In addition, in this embodiment, the spring pressure of the disc spring 15 is obtained, and between the gland 12 and the enlarged diameter flange 8,
Needless to say, primary sealing is performed by the laminated packing materials 13, 13 having a mountain-shaped cross section, and the sealing performance is greatly improved.

Moreover, in this embodiment, the sealing packing material 13
In addition, the stepped portion 17 of the gland 12 and the fitting hole 10
Since a secondary sealing state is obtained by the metal touch by the receiving surface portion 16 and the O-ring 19, it is possible to completely prevent fluid leakage.

In addition to the above, due to the O-ring 19 and the O-ring (not shown) attached to the metal contact surface, for example, the sealing material 13 itself may be plastically deformed or the plate may become damaged due to long-term use under high temperature and high pressure. Even if the spring 15 deteriorates, by adjusting the amount of screwing of the retightening gland 12 into the fitting hole 10,
Place the packing material 13 on the bottom surface of the gland 12 and the stem 5.
Since it can always be compressed to an ideal state between the upper surfaces of the enlarged diameter flange portion 8, there is no fear that the sealing performance will deteriorate significantly due to deformation of the packing material 13 itself or deterioration of the disc spring 15.

Although the above embodiment is applied to a ball valve, the present invention is not limited thereto, and can be easily applied to butterfly valves and the like based on the same principle. .

In addition, in the above embodiment, the stem 5 has a concave groove 1.
8 and by placing an O-ring 19 in the groove 18, the inner circumferential surface of the gland 12 and the stem 5
Although the O-ring 19 is not used, only the compression seal of the packing material 13 and the metal touch seal of the receiving surface part 16 and step part 17 prevent fluid leakage. As such, the use of O-ring 19 is optional depending on the implementation.

Effects of the invention As described above, the present invention includes a retightening gland that is screwed into the upper end opening of the fitting hole, and a packing material is provided between the lower surface of the retightening gland and the upper surface of the expanded diameter flange of the stem. At the same time, a disc spring is arranged between the lower surface of the expanded diameter flange and the corresponding wall of the fitting hole, and the spring pressure of the disc spring urges the expanded diameter flange of the stem in the direction of the gland for additional tightening. The packing material is characterized by exhibiting sealing properties, so the packing material can be reliably sealed, and even if it is used for a long period of time under high temperature and pressure, the sealing material itself will be damaged. Even if the disc spring is plastically deformed or the disc spring deteriorates, by adjusting the amount of screwing of the retightening gland into the fitting hole, the secondary seal between the metal touch and the O-ring will prevent deformation of the packing material itself, as in the past. This has useful effects such as there is no risk that the sealing performance will deteriorate due to deterioration of the disc spring or the like.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of essential parts of a shaft sealing device according to an embodiment of the present invention, and FIG. 2 is a sectional view showing a ball valve equipped with a coaxial sealing device. DESCRIPTION OF SYMBOLS 1... Valve body, 5... Stem, 8... Expanded diameter flange part, 9... Shaft mounting part, 10... Fitting hole, 11...
Female thread part, 12...Gland for additional tightening, 12a...
...Male thread part, 13... Packing material, 15... Belleville spring, 16... Receiving surface part, 17... Step part, 19...
O-ring.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In a device for sealing a stem formed with an enlarged diameter flange portion into a fitting hole formed in a shaft mounting portion of a valve body, the upper end opening of the fitting hole A gland for additional tightening is provided, and a packing material is provided between the lower surface of the gland for additional tightening and the upper surface of the enlarged diameter flange of the stem, and a corresponding wall between the lower surface of the enlarged diameter flange and the fitting hole. A disc spring is disposed in between, and the spring pressure of the disc spring urges the enlarged diameter flange of the stem in the direction of the tightening ground, and the stem shaft sealing part is hermetically sealed with the packing material. Shaft sealing device for valve stems. (2) In a device for sealing a stem formed with an enlarged diameter flange into a fitting hole formed in a shaft mounting portion of a valve body, a gland for retightening is screwed into the upper end opening of the fitting hole. A packing material is disposed between the lower surface of the retightening gland and the upper surface of the enlarged diameter flange of the stem, and a disc spring is disposed between the lower surface of the enlarged diameter flange and the corresponding wall of the fitting hole. Then, the expanding diameter flange of the stem is urged in the direction of the gland for retightening by the spring pressure of the disc spring, so that a primary seal is formed with the packing material, and the outer circumferential surface of the stem is connected to the gland. A shaft sealing device for a valve stem, which is configured to form a secondary seal by an O-ring installed between the inner circumferential surface of the shaft mounting part and a stepped part formed on the receiving surface of the shaft mounting part and the ground.