JPH0446121Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention is applicable to pistons and cylinders, piston rods and cylinder covers, or swivel joints in hydraulic circuits, which are assembled concentrically with each other in the axial direction. This invention relates to a gasket used as a sealing means for mechanical elements that move relative to each other or rotate relative to each other.

(Prior Art) As a sealing means for piston rods, cylinder covers, etc., as shown in FIG. A seal ring 3 made of a synthetic resin material and a back ring 4 that biases the seal ring 3 are provided.
A packing is widely used in which the piston rods are inserted in a concentric combination so that the seal ring 3 urged by the back ring 4 slides sealingly on the circumferential surface of the piston rod 1. (Refer to Japanese Utility Model Publication No. 59-8035) Nitrile rubber is mainly used as the material for the back ring 4 because it has excellent elastic force for urging the seal ring 3 and excellent pressure resistance against the pressure of the working fluid. There is.

(Problems to be solved by the invention) The nitrile rubber material used as the material for the back ring 4 in the conventional packing described above has the property of hardening at high temperatures and becoming brittle at low temperatures, thereby losing its elasticity. Therefore, in high and low temperature environments, the biasing force of the back ring 4 against the seal ring 3 may decrease, resulting in a decrease in sealing performance.

The object of the present invention is to solve the above-mentioned problems and to present a packing structure that does not reduce sealing performance even in high and low temperature environments.

(Means for solving the problem) As a means to prevent deterioration of sealing performance in high and low temperature environments, a silicone rubber material that does not harden in high temperature environments and does not become brittle in low temperature environments is used as a backling material. Although it is possible to use silicone rubber materials, although they are highly resistant to heat and cold, they have poor pressure resistance, and this, along with the high operating pressures seen in recent pressure equipment, does not necessarily provide a complete solution. It can't be.

In view of the problems with the packing according to the conventional technology described above, the present invention provides an annular seal having at least a circular cross-sectional shape in a back ring that urges a seal ring that seals and slides on one of the circumferential surfaces of the two relatively moving members. An inner ring is formed with a hollow space, is made of a rubber-like elastic material with high heat resistance and cold resistance, and has a cross-sectional shape substantially the same as the annular hollow space, and is enclosed within the annular hollow space. It is something.

(Function) In the packing of the present invention having the above configuration, the inner ring made of a rubber material with heat resistance and cold resistance is hardened in a high temperature environment or brittle in a low temperature environment. The outer cover of the back ring made of a rubber material with high pressure resistance protects the inner ring made of a rubber material with poor pressure resistance. As the pressure increases, it is strongly compressed in the axial direction, pressing the back ring in the radial direction and strengthening the sealing function of the seal ring.

(Embodiment) In the embodiment shown in FIG. 1, the seal ring 3 is inserted into the seal mounting groove provided in the cylinder cover 2 together with the seal ring 3 assembled concentrically, and the seal ring 3 is brought to the circumferential surface side of the piston rod 1. The biasing back ring 4 is composed of two annular bodies that are divided by a joint surface having a substantially doglegged cross-sectional shape and combined with each other to form an annular cavity with a circular cross section, and is heat resistant. An inner ring 5 made of a silicone rubber material having a high temperature and cold resistance and having a circular cross section is enclosed within the annular cavity.

In the embodiment shown in FIG. 2, the joint surfaces of the back ring 4 divided into two parts are formed into a stepped shape that engages with each other, and in the embodiment shown in FIG. The cross-sectional shape of the back ring 4 is approximately semicircular, and an opening for inserting the inner ring 5 is provided on the side of the back ring 4.

In the illustrated embodiment, a packing formed by combining a seal ring 3 and a back ring 4 is shown to be inserted into a packing mounting groove 3 on the side of the cylinder cover 2 and to slide sealingly against the circumferential surface of the piston rod 1. However, it goes without saying that the present invention can be applied to a packing that is attached to a piston inserted into a cylinder and slides sealingly against the inner peripheral surface of the cylinder.

(Effect of the invention) As described above, the seal ring of the present invention is attached to one of the relative movement 2 members together with the concentrically assembled seal ring, and the seal ring is moved into the relative movement 2 member.
The back ring that urges the other circumference of the member,
It has a structure formed by an inner ring made of a rubber-like elastic material with high heat resistance and cold resistance, and an outer cover made of a rubber-like elastic material with high pressure resistance. As a result, the elastic force of the inner ring prevents the elastic force of the back ring from decreasing due to hardening in high-temperature environments or embrittlement in low-temperature environments, and the influence of high pressure on the inner ring is reduced to the outer cover. This protects the seal and maintains the sealing performance of the packing well under all temperature environments.Furthermore, as the fluid pressure increases, the internal ring contained in the back ring is strongly compressed in the axial direction, which protects the back ring. Press in the radial direction to strengthen the sealing function of the seal ring.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of one embodiment of the present invention, FIGS. 2 and 3 are partial cross-sectional views of other embodiments of the present invention, and FIG. 4 is a conventional technology. It is a partial sectional view of an example of a packing. 1... Piston rod, 2... Cylinder cover, 3... Seal ring, 4... Back ring,
5...Inner ring.

Claims (1)

[Scope of utility model registration request] The two members 1 and 2 are made of synthetic resin material and have a cylindrical shape, and are inserted into a gasket mounting groove provided in one of two members 1 and 2 that are concentrically combined with each other to make relative movement. 2, and a back ring 4 made of a rubber-like elastic material and concentrically assembled with the seal ring 3 to urge the seal ring 3. In the packing, the back ring 4 is formed with an annular cavity having at least a circular cross-sectional shape, and is made of a rubber-like elastic material with high heat resistance and cold resistance, and is approximately equivalent to the annular cavity. The packing includes an inner ring 5 having a cross-sectional shape in the annular cavity.