JPS6314045Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a shaft sealing device for a Stirling cycle engine.

A Stirling cycle engine repeatedly undergoes isothermal compression, isovolume change, and isothermal expansion of a working fluid (helium, hydrogen, nitrogen, or a mixture thereof), and is used as a motor, heat pump, or refrigerator, or as a refrigerator. It can function as both a motor and a prime mover. In order to prevent the output or thermal efficiency of this Stirling cycle engine from decreasing, it is important to
The purpose is to seal the high-pressure working fluid to prevent leakage. In fact, leakage of the working fluid in the closed circuit not only reduces the output and thermal efficiency of the engine, but also causes the engine to stop, making it difficult to maintain stable operation over a long period of time.

On the other hand, Stirling cycle institutions generally
a reciprocatable piston rod, one end of which cooperates with the crosshead or swashplate, extends into the cylinder and is connected to the piston within the cylinder;
A compressor space is defined between the housing and the piston, which constitute a back pressure chamber therein. Various seals for sealing the piston rod are arranged at both ends of the back pressure chamber to prevent the high pressure working fluid in the compression section space from leaking into the low pressure crank chamber via the back pressure chamber.

Conventionally, attempts have been made to employ various types of shaft sealing devices such as roll socks as the shaft sealing device located at the rear end of the back pressure chamber, that is, on the crank chamber side. For Stirling cycle engines used under high pressure conditions, no practical shaft sealing device has yet been proposed that is effective in preventing gas leakage from the back pressure chamber to the crank chamber.

In view of the above, this invention was made for the purpose of providing a shaft sealing device that effectively prevents gas leakage from the back pressure chamber.

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

A piston 2 reciprocating within the cylinder 1 is connected to a piston rod 3, which extends into a crank chamber 5 through a housing 4 provided at an end within the cylinder.

Here, a seal ring 6, which is a front-stage shaft sealing device, and a rear-stage shaft sealing device 7 are provided at both ends of the housing 4, and a back pressure chamber 8 is formed therebetween.

The back pressure chamber 8 communicates with the compression chamber 10 through a check valve 9.

In the above configuration, during the stroke, the high pressure gas whose pressure fluctuates in the compression chamber 10 leaks from the front shaft sealing device and enters the back pressure chamber 8, increasing the pressure in the back pressure chamber. When the atmospheric pressure becomes lower than the atmospheric 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 air pressure in the back pressure chamber is maintained at a value close to the lowest value during the stroke of the compression chamber.

However, in the Starling institution,
Since the pressure inside the back pressure chamber is maintained at a much higher value than the pressure in the crank chamber, that is, the low pressure side, the gas in the back pressure chamber on the high pressure side leaks into the crank chamber through the rear shaft sealing device, and the engine This causes performance deterioration.

The present invention provides a shaft seal device which is effective in preventing gas leakage from the back pressure chamber 8 to the crank chamber 5, and comprises a seal ring body 1 made of synthetic resin which slides against the outer circumferential surface of the piston rod 3 to seal the gap.
The seal ring body 11 is made up of an inner peripheral surface 14 which is in contact with the outer peripheral surface of the piston rod 3, a metal holder ring 12 which holds the seal ring body 11 in contact with the outer peripheral surface of the piston rod 3, and an O-ring 13 which seals between the periphery of the metal holder ring 12 and the casing.
From the high pressure side to the low pressure side and radially inward
An outer peripheral inclined surface 15 inclined at an angle of 40° to 60°
The inner surface 16 faces the high pressure side, and the outer surface 17 faces the low pressure side, forming a trapezoidal cross section.

Further, the metal holder ring 12 has an inner circumferential inclined surface 18 inclined at an inclination angle corresponding to the outer circumferential inclined surface 15 of the seal ring main body 11, and the outer circumference is an O-ring located between the outer circumferential inclined surface 15 and the casing. 13
sealed by.

Here, the metal holder ring has a synthetic resin seat ring 20 on its inner circumferential side so as to fill the gap between it and the outer circumference of the piston rod 3.

When the shaft sealing device for a Stirling cycle engine is configured according to the present invention, even if shaft runout occurs in the piston rod 3 during engine operation,
Seal ring body 11 and metal holder ring 1
2 integrally follows the axial runout of the piston rod 3, and the contact relationship between the inclined surface of the seal ring body 11 and the inclined surface of the metal holder ring 12 is maintained stably. Therefore, the sealing properties of the contact portion between the seal ring body and the holder ring are maintained well.

Therefore, even if axial vibration occurs in the piston rod 3, no deterioration of the sealing property occurs at the contact point between the seal ring body and the holder ring, and good sealing properties are exhibited.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of a Stirling cycle engine having a shaft sealing device according to an embodiment of the present invention. Second
The figure is an enlarged cross-sectional view showing the installed state of the shaft sealing device. In the diagram; 1... cylinder, 2... piston, 3...
... Piston rod, 4 ... Housing, 8 ... Back pressure chamber, 10 ... Compression chamber, 11 ... Seal ring body, 12 ... Metal holder ring, 13 ... O
-Ring, 14... Inner peripheral surface of the seal ring body,
15... Outer peripheral inclined surface of the seal ring main body, 16...
...inner surface, 18...inner peripheral inclined surface of metal holder ring, 20...synthetic resin seat ring.

Claims (1)

[Scope of utility model registration request] A seal ring body made of synthetic resin, a metal holder ring that holds the seal ring body against the outer periphery of the seal ring body, and a metal holder ring that is located on the outer periphery of the holder ring and seals between the holder ring and the casing. A shaft sealing device for a piston rod of a Stirling cycle engine consisting of an O-ring, in which the seal ring body has an inner peripheral surface that contacts the outer circumference of the piston rod, an outer surface that faces the low pressure side, and an inner surface that faces the high pressure side. an inner peripheral inclined surface having a trapezoidal cross section consisting of a side surface and an inclined outer circumferential surface inclined radially inward from the high pressure side to the low pressure side, and on which the metal holder ring is in contact with the inclined outer circumferential surface of the seal ring main body; 1. A shaft sealing device for a Stirling cycle engine, characterized in that a synthetic resin seat ring is provided on the inner peripheral side of a metal holder ring in a gap between the holder ring and the piston rod.