JPH0223907Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention is a packing or flange that is placed around a shaft that rotates or reciprocates, such as a valve shaft or a drive shaft of a pump, or on the outer periphery of a piston that slides inside a cylinder. The present invention relates to a sealing structure such as an O-ring disposed between a flange and a flange, and particularly relates to a sealing structure such as a packing or an O-ring using a material with large thermal expansion/contraction such as synthetic resin or synthetic rubber.

If an annular space is provided between two parts to be sealed, and a sealing member such as packing or O-ring made of synthetic resin or synthetic rubber is placed in the space, the sealing member may heat up. When cooling is repeated, when the temperature is high, it expands and the compression allowance becomes large, and when the temperature is low, it contracts and becomes smaller. Therefore, it is necessary to ensure that sufficient sealing force can be obtained even during low-temperature shrinkage.

BACKGROUND ART Conventionally, a sealing member has been urged against a sealing surface using an elastic member. An example of this is shown in Japanese Utility Model Publication No. 47-13278. This is a sealing member made of Teflon (registered trademark) that is biased against the sealing surface by a strong spring. By biasing the sealing member with the elastic member, the sealing member is strongly pressed against the sealing surface even at low temperatures, and pressure contact force can be ensured.

Problems that the invention attempts to solve However, in this case, leakage occurs within a short period of time after use. That is, the sealing member is pressed against the sealing surface under a large external force by an elastic member so that the sealing member can be sealed even at low temperatures. Therefore, at high temperatures, the sealing member expands and receives a strong biasing force from the elastic member, so that the compression allowance becomes larger than necessary, and permanent strain accumulates, making it impossible to seal.

The technical problem of the present invention is to maintain a good sealing effect for a long period of time even when the sealing member is repeatedly heated and cooled.

Means for Solving the Problems The technical means of the present invention taken to solve the above technical problems is to form a synthetic resin, synthetic rubber, etc. in the annular space formed between the two members to be sealed. A holding member made of bimetal absorbs the thermal expansion and contraction of the sealing member. The tapered surface of a disc spring is placed in contact with one end of the bimetal.

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

The sealing member expands and contracts in response to temperature changes.
On the other hand, the bimetal expands and contracts and moves on the tapered surface of the disc spring. Therefore, the expansion and contraction of the sealing member is absorbed by the expansion and contraction of the bimetal via the elastic force of the disc spring.

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

Since the bimetal absorbs the expansion and contraction of the sealing member through the disc spring through the disc spring, wear and permanent deformation do not occur, resulting in a long life.

In addition, by deforming the bimetal on the tapered surface of the disc spring, it is possible to absorb the expansion and contraction of the sealing member while maintaining the large elastic force of the disc spring. Even if it is a member, it can be reliably sealed.

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

Example 1: See FIG. 1 This example is applied to a packing structure for a valve stem.

A rotatably operated valve shaft 2 is installed in a concave groove of a valve casing 1. A flange 3 having a tapered lower surface is formed on the valve shaft 2. An annular space 6 is formed between the inner peripheral wall 4 and bottom wall 5 of the groove, and the lower surfaces of the valve shaft 2 and flange 3. An annular packing 7 having a trapezoidal cross section is accommodated in the annular space 6. A corner of the outer periphery of the lower end of the packing 7 is cut off and an O-ring 8 is placed thereon.
The upper end of the flange 3 is fixed with a snap spring 9.

A seat bell 10, a disc spring 11, and a bimetal 12 are arranged between the packing 7 and the bottom wall 5. The bimetal 12 is formed by bonding two rectangular metal plates with different coefficients of thermal expansion and bending them to form a cylindrical shape with ends, with the outer side having higher expansion than the inner side.

The packing 7 seals the tapered surface of the flange 3, and the O-ring 8 seals between the packing 7 and the inner peripheral wall 4.

The bimetal 12 contracts and closes on the bottom wall 5 at high temperatures and expands at low temperatures in response to temperature changes. and,
The position of the upper surface of the bimetal 12 in contact with the lower surface of the disc spring 11 changes, causing the disc spring 11 to move up and down. When the temperature is high, the disc spring 11 is lowered and the annular space between the tapered surface of the flange 3 and the seat cap 10 is widened, and when the temperature is low, the disc spring 11 is raised and the annular space is narrowed.

Embodiment 2: See FIG. 2 This embodiment is also applied to a packing structure for a valve stem, and components corresponding to those in FIG. 1 are given the same reference numerals and detailed explanations will be omitted.

Inner peripheral wall 4 and top wall 21 of valve casing 1 and valve shaft 2
An annular space 6 is formed between the upper surface of the flange 3 and the upper surface of the flange 3. The lower surface of the flange 3 is fixed with a snap spring 9. A packing 7 having a square cross section is housed in an annular space 6, and an O-ring 8 is disposed therein. Packing 7
A seat ring 10, a disc spring 11, and a cylindrical bimetal 12 with an end are arranged between the flange 3 and the flange 3. The deformation effect of the bimetal 12 with respect to temperature changes is similar to that in FIG.

Embodiment 3: See Fig. 3 This embodiment also has a packing structure for the valve stem, and the flange formed on the valve stem is the same as in Fig. 2.
Components corresponding to those in FIG. 2 are given the same reference numerals and detailed explanations will be omitted.

Inner peripheral wall 4 and top wall 21 of valve casing 1 and valve shaft 2
An annular space 6 is formed between the flange 3 and the flange 3.
A packing 7 having a square cross section is housed in an annular space 6, and an O-ring 8 is disposed therein. A bimetal 12 having a cylindrical shape with an end and a disc spring 11 are arranged between the lower surface of the flange 3 and a snap spring 9 attached to the inner circumferential wall 4.

The inside of the bimetal 12 has a higher expansion side than the outside. Then, expand, contract, and close the top surface of the disc spring 11.
The flange 3 moves up and down.

[Brief explanation of the drawing]

1 to 3 are cross-sectional views showing an embodiment of the seal structure of the present invention. 1: Valve casing, 2: Valve stem, 3: Flange,
6: Annular space, 7: Packing, 11: Belleville spring,
12: Bimetal.

Claims (1)

[Scope of utility model registration request] An annular sealing member made of synthetic resin, synthetic rubber, etc. is arranged in an annular space formed between two members to be sealed, and thermal expansion and contraction of the sealing member is absorbed by a holding member made of bimetal. A seal structure in which a bimetal is formed in a cylindrical shape so as to expand and contract in response to temperature changes, and the tapered surface of a disc spring is placed in contact with one end of the bimetal.