JPS6255446A - Power piston seal mechanism for stirling engine - Google Patents

Abstract

PURPOSE:To achieve the stabilizing of sealing performance and engine output by providing cuts on the upper surface facing to the compression chamber of piston rings being fitted in he ring grooves of a power piston. CONSTITUTION:In the ring grooves of a power piston 5, inner rings 13 are arranged in the inner circumference of grooves, and upper and lower plain rings 6 are arranged on the outer circumference thereof. On the upper surfaces facing to a compression chamber 10 of inner rings 13, many cuts are provided in the radial direction, and the lower surfaces facing to a buffer chamber 12 thereof are made to be flat surface. Thus, when the compression chamber 10 has a higher pressure, since each of inner rings 13 is pressed down toward the bottom surface to be sealed by the flat surface, secure sealing can be obtained, and when the buffer chamber 12 has a higher pressure, while each of the inner rings 13 is pressed toward the upper surface, the gas inside the buffer chamber flows into an operating chamber through the cuts, and accordingly leak gas quantity can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a sealing mechanism for a power piston of a Stirling engine.

[Conventional technology]

FIG. 3 is a diagram showing a schematic configuration of a conventional displacer type cooling engine. In this figure, 1 is a heater, 2 is a regenerator, 3 is a cooler, 4 is a displacer, and 5 is a
is a power piston. In this power piston 5,
20 is a ring groove provided at the top and bottom, and 21 is a ring land. Further, 6 is a plain ring provided in the ring groove 20 and slides on the inner wall of the cylinder 11, 7 is an inner ring provided inside this plain ring 6, and 8 is a plain ring provided on the inner wall of the cylinder 11 by stretching these rings 6 and 7. It is a tension ring for pressing. Also, 9 is an expansion chamber, 1
0 is a compression chamber, and 12 is a buffer chamber.

In such a configuration, the plain ring 6 and the inner ring 7 are stretched by the tension ring 8 and pressed against the cylinder 11 to seal gas between the compression chamber 10 and the buffer chamber 12.

[Problem that the invention seeks to solve]

In the power piston sealing mechanism of such a conventional Stirling engine, foreign objects,
Due to the intervention of dust etc., the upper surface of the piston ring
The leakage resistance on the underside changes slightly, which can cause the seal to become directional and result in non-uniform sealing performance. As a result, the pressure difference between the compression chamber 10 and the buffer chamber 12 fluctuates, and the pressure in the compression chamber 10 fluctuates between each cycle. In particular, the time-averaged pressure level in the compression chamber 10 fluctuates, causing engine output to fluctuate. There was a problem.

This invention was made to solve the above-mentioned problems, and it not only makes the sealing performance of the piston ring uniform during engine operation, but also eliminates pressure fluctuations in the compression chamber and buffer chamber between each cycle, making it stable. It is an object of the present invention to provide a sealing mechanism for a power piston of a Stirling engine, which can stabilize the time-average pressure level of a compression chamber and stabilize the engine output.

[Means for solving problems]

The sealing mechanism for the power piston of a Stirling engine according to the present invention forcibly gives directionality to the seal using an inner ring having a notch on one side, and seals the plain ring by the gas pressure difference between the compression chamber and the buffer chamber. It is made to seal against gas by stretching it.

[Effect]

In this invention, the seal is given directionality by inserting the inner ring having a notch in a certain direction into the piston groove, and the resulting gas pressure difference between the compression chamber and the buffer chamber causes the plain ring to move above the ring groove. Alternatively, it is pressed against the lower surface, suppressing uneven sealing performance of the piston ring, improving gas sealing performance, and stabilizing the pressures in the compression chamber and buffer chamber.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, the same reference numerals as in FIG. 3 indicate the same or corresponding parts. 13 is an inner ring provided inside the plain ring 6, and as shown in detail in FIG. 2, notches 30 are formed intermittently on one surface of the inner ring. Both the upper and lower inner rings 13 have their notches 30.
is arranged so that it is on top.

Next, the effects will be explained.

As shown in FIG. 1, when the inner ring 13 of the piston ring is installed with its notch 30 facing upward, when the pressure in the compression chamber 10 becomes higher than the buffer chamber 12, the piston ring moves into the ring groove 20. Pressed against the bottom surface. At this time, since there is no notch on the lower surface of the inner ring 13, gas leakage from the compression chamber 10 toward the buffer chamber 12 is almost zero due to this and the plain ring 6.

That is, this means that gas leakage resistance is high.

On the other hand, when the pressure in the compression chamber 10 becomes lower than the pressure in the buffer chamber 12, the piston ring is pressed against the upper surface of the ring groove 20, but at this time, a notch 30 is formed on the upper surface of the inner ring 13. Blow-through occurs from the buffer chamber 12 to the compression chamber 10 via the notch and the abutment of the plain ring 6. That is, this means that gas leakage resistance is low.

Here, the pressure in the compression chamber 10 is determined by the amount of gas leakage from the compression chamber 10 to the buffer 12 during one cycle and the
As a result, in the above configuration, the lowest pressure in the compression chamber and the pressure in the buffer chamber are approximately equal, and the piston ring is approximately at the piston ring land. It is in a state where it is strongly pressed downward, making it easier to prevent foreign objects, dirt, etc. from intervening, and maintaining stable sealing performance over a long period of time.

As a result, engine output can be stabilized.

Also, cut the inner ring 13 of the piston ring into the notch 3.
When installed so that 0 is at the bottom, the maximum pressure of the compression chamber 10 and the pressure of the buffer chamber 12 are approximately equal.

That is, a stable pressure state opposite to the above can be created, and in this case also, the same stability of sealing performance as in the above embodiment can be ensured, and the engine output can be stabilized.

In the above embodiment, a three-piece piston ring consisting of two plain rings and an inner ring was described, but the present invention is similar to that shown in FIGS. 4(a) and 4(b).
As shown in the figure, it can also be used in the case of a one-piece piston ring. That is, in this embodiment, a plurality of grooves 15 are provided in the one-piece piston ring 14 in the radial direction, so that the leakage resistance of the seal is directional as in the above embodiment.

Also, as a modification of this Fig. 4, Figs. 5(a) and (b)
), a plurality of protrusions 16 may be provided in the radial direction of the cliff (the same effect as in the above embodiment can be achieved).

Further, in each of the above embodiments, a case was explained in which a groove (notch) or a protrusion was provided in the piston ring as a means for imparting directionality to the seal, but this means is not limited to the above embodiments. For example, a configuration as shown in FIGS. 6 and 7 may be used.

That is, in the embodiment shown in FIG.
has been established. In this case, if a piston ring similar to the conventional piston ring is used, the same effect as in the case where the piston ring is provided with a notch can also be obtained with this embodiment.

Further, in the embodiment shown in FIG. 7, a plurality of protrusions are provided in the radial direction on the upper inner surface of the upper and lower ring grooves 20 of the power piston 5, and this embodiment also provides the same effect as the above embodiment. It will be done.

Furthermore, in the above embodiment, the case where the piston rings are provided in two stages has been described, but this may be in any number of stages.
The same effects as in the above embodiment are achieved.

〔Effect of the invention〕

As described above, according to the power piston sealing mechanism according to the present invention, by attaching an inner ring having a notch on one side to each piston ring groove in a fixed direction,
Since the piston ring has a predetermined seal direction,
This has the effect of stabilizing sealing performance and providing stable engine output.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional configuration diagram showing a sealing mechanism of a power piston of a Stirling engine according to an embodiment of the present invention, and FIG.
The figure shows an inner ring used in the sealing mechanism, FIG. 3 shows a conventional sealing mechanism, and FIGS. 4 and 5 show another example of the present invention in which a piston ring is provided with seal directionality imparting means. Embodiment Figures 6 and 7 are diagrams showing other embodiments of the present invention in which a ring groove is provided with seal directionality imparting means. 5... Power piston, 6... Plain ring, 8...
...Tension ring, 10...Compression chamber, 12...
Buffer chamber, 13...inner ring, 14...1
Piece-type piston ring, 15.17...Groove, 16.
18...Protrusion, 20...Ring groove, 30...Notch. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (4)

[Claims] (1) A piston ring installed in the power piston of a Stirling engine that separates a compression chamber and a buffer chamber; A sealing mechanism for a power piston of a Stirling engine, characterized in that it is equipped with means for imparting seal directionality to vary leakage resistance. (2) The piston ring is composed of a plain ring and an inner ring provided inside the plain ring, and the seal directionality imparting means is intermittently provided on one side of the inner ring and is provided on one side of the plain ring. A sealing mechanism for a power piston of a Stirling engine according to claim 1, characterized in that the sealing mechanism is a notch communicating with a joint. (3) The seal directionality imparting means is formed of a plurality of grooves provided in the radial direction on either the lower or upper inner surface of the piston ring groove of the power piston and communicating with the abutment of the piston ring. A sealing mechanism for a power piston of a Stirling engine as claimed in claim 1. (4) The seal directionality imparting means is provided in a radial direction on either the lower or upper inner surface of the piston ring groove of the power piston, and the space between the adjacent two communicates with the abutment of the piston ring. A sealing mechanism for a power piston of a Stirling engine according to claim 1, characterized in that the sealing mechanism is composed of a plurality of protrusions.