JP3092255B2 - Seal ring - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seal ring for preventing the occurrence of cracks by improving the arrangement of carbon fibers filled in a synthetic resin, and more particularly, to a seal ring for a piston rod of a Stirling cycle engine. The present invention relates to a seal ring suitable for sealing working gas leaking along an outer peripheral surface.

[0002]

2. Description of the Related Art The use of a seal ring having a trapezoidal cross section whose outer peripheral surface is held by a metal holder ring for sealing around the outer periphery of a reciprocating piston rod is disclosed, for example, in Japanese Utility Model Publication No. Sho 63-14045. As is disclosed in US Pat.

[0003] As disclosed in the publication, the Stirling cycle engine does not leak high-pressure working gas from a compression section constituting a closed circuit of the working fluid in order to prevent a decrease in output or thermal efficiency. For this reason, the seal ring as described above is arranged around the reciprocating piston rod.

A seal ring having such an important sealing effect is formed by filling a carbon fiber in a base material of a synthetic resin (preferably polytetrafluoroethylene).

When a seal ring of this type is used in a Stirling cycle engine under severe conditions in which high-pressure gas acts on the inner surface of a seal ring filled with carbon fibers, a central through-hole that slides on the outer peripheral surface of the piston rod is formed. Cracks occur radially outward from the inner peripheral surface.

[0006]

When a crack is generated in the radial direction from the inner peripheral surface of the seal ring, the durability of the seal ring is significantly reduced, and an obstacle for stabilizing the output of the engine. It has become.

Therefore, an object of the present invention is to solve the above-mentioned disadvantages of the prior art.

[0008]

In order to solve the above-mentioned problems, the present invention employs means for improving the longitudinal direction of carbon fibers in a synthetic resin. In forming the seal ring, raw materials of polytetrafluoroethylene and carbon fiber are placed in a mold and compression-molded to produce a material of an arbitrary shape. In this material, since the longitudinal direction of the carbon fiber is almost constant, the material is processed into a cylindrical shape by using this direction so that the longitudinal direction of the carbon fiber is in the axial direction. The cylindrical material is cut into a seal ring, and the carbon fibers are directed in the axial direction of the seal ring.

Specifically, the present invention provides a trapezoidal cross section, in which a piston rod reciprocates in a central through hole and a metal holder ring contacts an outer peripheral surface inclined from a high pressure side to a low pressure side, In a seal ring in which carbon fiber is filled in a synthetic resin, the carbon fiber is
Provided is a seal ring characterized by being filled with wt%, wherein the longitudinal direction of the carbon fibers is arranged along the axial direction of the seal ring.

[0010] Preferably, the seal ring is in contact with the cylinder via a metal holder ring via an O-ring, the piston rod is connected to a piston for a Stirling engine, and the inner surface thereof faces the high pressure side.

[0011]

According to the present invention, since the longitudinal direction of the carbon fibers in the synthetic resin is oriented in the axial direction of the seal ring, cracks that run outward in the radial direction are prevented.
Carbon fiber resists and suppresses cracks.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of the seal ring of the present invention will be described below focusing on a preferred application example. A piston rod 3 is connected to a piston 2 that reciprocates in the cylinder 1, and the piston rod 3 extends to a crank chamber 5 through a housing 4 provided at an end in the cylinder. Here, at both ends of the housing 4, a seal ring 6 as a front shaft sealing device is provided.
And a rear shaft sealing device 7, between which a back pressure chamber 8 is provided.
Is formed. The back pressure chamber 8 is connected to the compression chamber 10 through a check valve 9.
Communicate with

In the above structure, during the stroke, the high-pressure gas whose pressure fluctuates in the compression chamber 10 leaks from the shaft sealing device at the front stage and enters the back pressure chamber 8 to increase the pressure in the back pressure chamber. When the pressure in the pressure chamber 10 becomes lower than the pressure in the back pressure chamber 8, the gas in the back pressure chamber is returned to the compression chamber via the check valve 9.

Therefore, the pressure in the back pressure chamber is maintained at a value close to the lowest value during the stroke of the compression chamber.

An effective shaft sealing device for preventing gas leakage from the back pressure chamber 8 to the crank chamber 5 is a synthetic resin seal ring which slides against the outer peripheral surface of the piston rod 3 to seal the gap therebetween. It is composed of a main body 11, a metal holder ring 12 which is in contact with the outer periphery of the seal ring main body 11 and holds the seal ring main body 11, and an O-ring 13 which seals between the periphery of the metal holder ring 12 and the casing. The seal ring main body 11 is inclined at an angle of 40 ° to 60 ° radially inward from the high pressure side to the low pressure side and the inner circumferential surface 14 which is in contact with the outer circumferential surface of the piston rod 3. An outer peripheral inclined surface 15 and an inner surface 16 facing the high pressure side
And an outer surface 17 facing the low pressure side to form a trapezoidal cross section.

The metal holder ring 12 has an inner peripheral inclined surface inclined at an inclination angle corresponding to the outer peripheral inclined surface 15 of the seal ring main body 11, and the outer periphery is an O-ring 13 located between the casing and the casing. Sealed.

The seal ring 11 is preferably made of polytetrafluoroethylene (PTFE) having a diameter of 10 to 50 μm.
m, carbon fiber having a length of 100 to 1000 μm
As shown in FIG. 2, the carbon fibers 8 are arranged so that the longitudinal direction thereof is oriented in the axial direction of the seal ring 11. Such an arrangement resists cracks that try to run radially outward and suppresses the occurrence of cracks.

In order to form the seal ring 11, the longitudinal direction of the carbon fiber is shifted from the axial direction of the seal ring from the raw material obtained by filling polytetrafluoroethylene and carbon fiber as raw materials in a mold, and then compressing the material. What is necessary is just to cut and machine in the cross-sectional shape of FIG.

[0019]

According to the present invention, since only the direction of the carbon fiber is devised, the flexibility of the seal ring is not impaired, and the other filler is particularly used without changing the compounding ratio of the carbon fiber. It is economical because it does not require it.

[Brief description of the drawings]

FIG. 1 is a sectional view of an application example of an example of the present invention.

FIG. 2 is a sectional view of a seal ring according to an example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder 2 Piston 3 Piston rod 11 Seal ring 18 Carbon fiber

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroyuki Katsuta 2-1-1 Asahi-cho, Kariya-shi, Aichi Aisin Seiki Co., Ltd. (72) Inventor Tetsumi Watanabe 2-1-1, Asahi-cho, Kariya-shi, Aichi Aisin Seiki (72) Inventor Yutaka Momose 2-1-1 Asahi-cho, Kariya-shi, Aichi Ai Shin Seiki Co., Ltd. (72) Inventor Naoki 2-1-1 Asahi-cho, Kariya-shi, Aichi Aisin Seiki Co., Ltd. (56) References JP-A-49-15622 (JP, A) JP-A-58-139550 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02G 1/053 F16J 15 / 26

Claims (2)

(57) [Claims] 1. A trapezoidal cross section, a piston rod reciprocates in a central through hole, and a metal holder ring contacts an outer peripheral surface inclined from a high pressure side to a low pressure side, and carbon fibers are filled in a synthetic resin. The sealing ring is filled with 10 to 40% by weight of carbon fiber and
The seal ring, wherein the longitudinal direction of the carbon fibers is arranged along the axial direction of the seal ring. 2. The seal ring according to claim 1, wherein the metal holder ring is in contact with the cylinder via an O-ring, the piston rod is connected to a piston for a Stirling engine, and an inner surface thereof faces the high pressure side.