JPS6140452A - Displacer sealing structure for stirling engine - Google Patents

Abstract

PURPOSE:To enhance the sealing ability of a displacer, by providing a second tension ring for preventing a piston ring on the displacer from vertically moving, in addition to a tension ring for urging the piston ring toward the inner surface of a cylinder. CONSTITUTION:There are provided, in a ring groove 5a formed in a displacer 5, a first tension ring 22 for urging a piston ring 21 toward a cylinder surface, and a U-like cross-sectioned shape and ring-like shape second tension ring 26 having a sealing function for urging the piston ring 21 downward of the ring groove 5a in the displacer 5. The tensions of the first and second tension rings 22, 26 are set such that the resultant force Fa for urging the piston ring 21 downward of the ring groove may be obtained irrespective of the reciprocating motion of the displacer, and the resultant force Fb for urging the piston ring 21 toward the cylinder surface may be contained in such a relationship as Fb>Fa.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a displacer seal structure for a Stirling engine. , [Prior Art] In general, a Stirling engine is an engine in which pressure fluctuations are generated in a cylinder by the reciprocating motion of a displacer, and the pressure fluctuations are applied to a power piston to obtain output. Shown in Figure 1.

FIG. 1 is a block diagram of a displacer type schooling engine, which is one of the typical configurations of a Stirling engine. In the figure, 1 is an expansion cylinder, 2 is a heater tube, 3 is a regenerator, 4 is a Tala tube, 5 is an air supply piston generally called a displacer, 6 is a displacer rod, and 7 is a sliding movement between the expansion cylinder 1 and the rod 6. 10th seal for sealing the gap, 8 is a compression cylinder, 9 is a cap → communication pipe for communicating the compression cylinder 8 and the expansion cylinder, 10 is a power piston, 11
12 is a power piston ring, 12 is a 20th rod seal for sealing the sliding gap between the compression cylinder 8 and the power piston rod 11, and 13 is a first connecting rod for converting the rotational force of the crankshaft into reciprocating motion of the displacer 5. ,
14 is a second connecting rod for converting the reciprocating motion of the power piston 10 into rotational force of the crankshaft; 15 is a crank for causing the reciprocating motion of the displacer 5 and the power piston 10 to be performed with a predetermined phase difference and at the same time obtaining rotational force. axis, 16
．． 17 is a main bearing of the crankshaft 15; 100 is a crankcase for holding the components 1 to 17 at predetermined positions; and 18 is a buffer chamber.

In the Stirling engine configured in this way,
If the heater tube 2 is continuously heated with a burner or the like, and the tara tube 4 is continuously cooled with water or the like, pressure fluctuations occur within the cylinder, which causes the power piston 10 to move up and down, allowing power to be extracted.

Further, FIG. 2 shows a piston ring 21 for sealing between the displacer 5 and the cylinder, and this piston ring 21 is made of a lubricant-free material with a step-cut abutment. FIG. 3 shows the piston ring 21 installed in the ring groove of the displacer 5, where 22 is a tension ring for applying force to press the piston ring 21 against the inner surface of the cylinder, and 5a is a ring provided on the displacer 5. It's a groove.

It has been found that the sealing performance of the air supply piston ring of the Stirling engine constructed in this manner is very poor.

That is, the force (F'l in FIG. 3) due to gas pressure acting on the piston ring 21 is very small due to the action peculiar to the displacer type cooling engine, and therefore the piston ring 21 is normally pressed against the cylinder surface by the tension ring 22. This provides a gas seal between the top and bottom piston rings. However, the piston ring 21 moves up and down within the ring isa of the displacer 5 due to the frictional force with the cylinder surface and the inertial force, and a gap is generated at the step-cut joint of the piston ring. It blows through.

[Summary of the invention]

This invention was made to eliminate the drawbacks of the conventional ones as described above, and in addition to the conventional tension ring for pressing the piston ring against the inner surface of the cylinder, a second tension ring is provided to prevent the piston ring from moving up and down. It is an object of the present invention to provide a displacer seal structure for a Stirling engine that can improve the sealing performance of the displacer by providing the following.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. Fourth
In the figure, the same reference numerals as in FIG. 3 indicate the same functional members.

22 is a first tension ring for pressing the piston ring 21 against the cylinder surface; 26 is the piston ring 2;
This is an annular second tension ring having a sealing function for pressing the displacer 1 downward into the ring groove 5a of the displacer 5, and its cross-sectional shape is U-shaped.

Next, in such a configuration, the force and direction acting on the piston ring 21 will be explained. In FIG. 4, F2 is a force (radial force) that presses the piston ring 21 against the cylindrical surface, and this force is the force given by the first tension ring 22. F3. F4 is a piston ring 21 generated as the displacer 5 reciprocates.
The sum of the frictional force and the inertial force generated on the piston ring 21 is shown.

F5. F6 is a force generated by the seal pressure difference generated between the upper and lower sides of the piston ring 21, and F7 is a force generated by the seal error # that presses the piston ring 21 against the cylinder surface. Further, F8 is the force by which the second tension ring 26 presses the piston ring 21 downward into the ring groove 5a.

The above-mentioned forces act on the piston ring 21, but in this embodiment, the resultant force Fa, B that presses the piston ring 21 downward in the ring groove, Fa=FB - (F5
+F3'') is obtained regardless of the reciprocating motion of the displacer 5, and the resultant force Fb that presses the piston ring 21 against the cylinder surface, that is, Fb-F2 +l'7, is always such that Fb>Fa is obtained regardless of the reciprocating motion of the displacer 5. The first and second tension rings 22.2
The tension is set at 6.

According to the configuration of this embodiment, the amount of gas leaking from the displacer piston ring can be reduced to about 1/20 compared to the conventional one, and even if the contact portion of the piston ring with the cylinder surface is worn out. The self-expanding action of the piston ring also provides a long-lasting, high-performance seal, making it possible to provide a practical Stirling engine.

In the above embodiment, the case where the second tension ring is installed between the top surface of the piston ring and the ring groove is explained, but the second tension ring is installed between the bottom surface of the piston ring and the ring groove. However, if the tension is set based on the same concept as in the above embodiment, the same effects as in the above embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the displacer seal structure for a Stirling engine according to the present invention, the piston ring mounted on the displacer is pressed against the cylinder surface by the first tension ring, and the piston ring is pressed against the cylinder surface by the second tension ring. Since the displacer is pressed downward or upward into the groove, the sealing performance of the displacer can be greatly improved compared to the conventional displacer 1, which is an effect that will be very effective for practical use of Stirling engines.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram showing a typical configuration example of a Stirling engine, Fig. 2 is a perspective view of a piston ring attached to a displacer of the Stirling engine, and Fig. 3 is a diagram showing a seal structure of a conventional displacer. , FIG. 4 is a diagram showing a displacer seal structure for a Stirling engine according to an embodiment of the present invention. 1... Expansion cylinder, 5... Displacer, 5a
...Ring groove, 10...Power piston, 21...
Piston ring, 22... first tension ring,
26...Second tension ring. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent: Ken Hayase, Patent Attorney - Figure 1 Figure 2 Figure 4

Claims (3)

[Claims] (1) A displacer seal structure for a Stirling engine in which pressure fluctuations are generated in the cylinder by the reciprocating motion of the displacer and the pressure fluctuations are applied to the power piston to obtain output, and the piston ring is attached to the displacer. a first tension ring for pressing the piston ring against the cylinder surface; and a second tension ring for pressing the piston ring either below or above the ring groove in which the piston ring is installed. Stirling engine displacer seal structure featuring: (2) Force Fb that the piston ring receives when it is pressed by the first and second tension rings
, Fa is always Fa<
The displacer seal structure for a Stirling engine according to claim 1, wherein the displacer seal structure is set to be Fb. (3) The second tension ring is formed in an annular shape with a U-shaped cross section, and is installed between the top or bottom surface of the piston ring and the ring groove so as to seal therebetween. A displacer seal structure for a Stirling engine according to claim 1 or 2, characterized in that: