JPH0726591B2 - Shaft sealing mechanism for multi-cylinder Stirling engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a shaft sealing mechanism for a multi-cylinder Stirling engine, and more particularly to a multi-cylinder Stirling engine having an improved Leningrad seal member with which a crosshead rod is slidably engaged. Regarding shaft seal mechanism.

(B) Conventional Technology and Problems FIG. 3 shows an example of a multi-cylinder Stirling engine, and the gas circuit of the engine is conceptually shown in FIG. Although the one shown in FIG. 3 can only see two cylinder chambers, it is actually a four-cylinder chamber, and at the top, four cylinder chambers are grouped together, and only one combustion chamber is required. As shown in FIG. 4, the heating chamber (H),
A heat exchange chamber composed of a regeneration chamber (R) and a cooling chamber (C) and a cylinder chamber having a piston (P) are alternately connected in an annular cascade. The working gas in each cylinder chamber is repeatedly compressed and expanded by mutual positions of pistons and external heating and cooling.

Conventionally, as shown in FIG. 3, pistons are arranged in a plurality of high-pressure cylinder chambers, and the pistons and the machine chamber to which lubricating oil is supplied are connected by a crosshead rod. In a multi-cylinder Stirling engine that synchronizes from the machine room via a shaft seal mechanism with a crossed rod, the purpose is to prevent both gas leakage from the high pressure room to the machine room and oil rise from the machine room to the high pressure room. A so-called Leningrad seal system is often used for the shaft sealing mechanism.

The Leningrad seal system is basically designed such that a pair of seal holders having a tapered cross-section of a resin sealing member of an abbreviated ball shape are sandwiched from above and below to provide a sealing effect, and the sealing member is shown in FIG. The shape was as shown in. However, according to an experiment conducted by the present inventors, the sealing member has a poor gas sealing property, and in terms of preventing oil rising, the performance is conspicuous, and further improvement of these functions has been desired.

(C) Means for Solving the Problems The present invention has been made to solve the above-mentioned problems, and prevents gas and oil from leaking from the shaft sealing mechanism to prevent the gas from the conventional shaft sealing mechanism. In order to improve the sealing performance and the instability of the oil seal performance, 1/3 to 1/2 of the axial length of the rod insertion hole should be placed in the middle of the crosshead insertion hole of the seal member. And a notch having a taper surface with a gradually reduced diameter on the machine chamber side at an angle of 1 to 7 ° with respect to the crosshead rod.

(D) Embodiments Embodiments of the shaft sealing mechanism of the multi-cylinder Stirling engine according to the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 shows a shaft sealing mechanism according to the present invention, and
FIG. 2 shows details of the Leningrad seal member 3 included in the shaft sealing mechanism of FIG. The pistons synchronized from the machine chamber through the crosshead rod 1 cause the gas in the cylinder chamber to change between high pressure and low pressure along with the distribution of the high temperature portion and the low temperature portion of the heat exchange chamber. In order to seal this gas, generally, a rod seal member 2 such as a cap seal is first arranged on the upper part of the shaft sealing mechanism. This rod seal member 2
Is responsible for most of the gas seal.

Referring to FIG. 1, a rod seal member 2 of 1 to 3 stages is first arranged in an upper stage around the crosshead rod 1, and if the cross-sectional shape of the seal member is rectangular, a lower space thereof is provided. Is the average pressure of the cylinder chamber, and when the cross-sectional shape is U-shaped or V-shaped and the opening faces upward, the lower space is kept at the lowest pressure of the cylinder chamber. In any case, the rod seal member 2 is responsible for most of the gas seal, and acts so that static pressure is applied to the Leningrad seal member 3, which is the final gas seal portion. On the other hand, the Leningrad seal member 3 has a final function as a gas seal and a seal function for preventing oil leakage from the lower machine room.

Next, the Leningrad seal member 3 according to the present invention will be described in comparison with the conventional Leningrad seal member 4 shown in FIG. In both cases, the first seal holder 6 presses the seal member against the second seal holder 7 by the gas pressure and the spring force of the spring member 5. The second seal holder 7 and the seal member are sealed by this pressing force, and the component of the pressing force acts as a hugging force between the sealing member and the crosshead rod 1 to exert a sealing action.

Since the conventional seal member 4 has the taper portion for returning the oil on the upper side of the shaft sealing portion, when the crosshead rod 1 moves downward, it exerts a wedge effect due to viscosity not only on the oil but also on the gas. It was causing the gas leak from the. Moreover, since the shape of the taper part lacks rigidity, the performance tends to vary, and the oil return capacity tends to vary.

The seal member 3 according to the present invention has a length of 1/3 to 1/2 of the axial length of the rod insertion hole in the middle portion of the cross head insertion hole, and 1 to 1 with respect to the cross head rod 1. A notch having a taper surface whose diameter is gradually reduced is provided on the machine room side at an angle of 7 °. Therefore, the contact portion between the seal member 3 and the crosshead rod 1 is left at a place where a component of the pressing force is likely to work, and gas sealing and oil sealing are performed at both upper and lower portions thereof. Since the oil return taper portion is provided in the middle of the contact portion, the gas together with the oil is not sent to the low pressure side due to the wedge effect.

Even if a little oil rises, it accumulates in the taper portion provided in the middle of the seal, and when the crosshead rod 1 moves downward, the oil causes a pressure rising wedge effect and spreads the seal member 3 You will return to the original machine room.
By any chance, the oil leaked to the upper part beyond the Leningrad seal member 3 will be scraped out to the outside by the dedicated oil scraping ring 8. Further, since the taper portion is provided in a highly rigid place, variation in shape is unlikely to occur, and accordingly, the oil return effect is also stably exhibited.

According to a gas leak and oil leak test conducted by the present inventor while keeping the pressure on the Leningrad seal at 50 atg, the conventional product had a gas leak of 25 cc / min per set, but in the case of the present invention, A value of 0.5 cc / min was shown, and a significant improvement in performance was observed as a result of visual observation of oil rising, indicating the superiority of the present invention.

(E) Effect of the invention Since the shaft sealing mechanism of the multi-cylinder Stirling engine according to the present invention is configured as described above, improvement in gas and oil sealing performance was also confirmed in the experiment by the present inventors.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional front view of a shaft sealing mechanism portion of a Stirling engine according to the present invention, and FIG. 2 is a vertical sectional front view of a Leningrad seal member included in the shaft sealing mechanism portion of FIG. 3 is a longitudinal sectional front view of a multi-cylinder Stirling engine, FIG. 4 is a diagrammatic explanatory view of a gas circuit of the Stirling engine of FIG. 3, and FIG. 5 is a longitudinal sectional front view of a conventional Leningrad seal member. is there. 1 ... Cross head rod 2 ... Rod seal member 3 ... Leningrad seal member according to the present invention 4 ... Conventional Leningrad seal member 5 ... Spring member 6 ... First seal holder 7 ... Second seal holder 8 …… Oil oyster ring

Claims (1)

[Claims] 1. A piston is arranged in each of a plurality of high-pressure cylinder chambers, and the piston and a machine chamber to which lubricating oil is supplied are connected by a crosshead rod, and a crosshead rod and a crosshead liner are connected. In a multi-cylinder Stirling engine, a resin seal member having an approximately abbreviated ball shape, a pair of seal holders for holding the seal member, and a spring member for applying a spring force to the seal member and the seal holder are disposed between the seal members. In the shaft-sealing mechanism, the seal member has a length of 1/3 to 1/2 of the axial length of the rod insertion hole at an intermediate portion of the cross-head rod insertion hole and is 1 to the cross-head rod. A shaft sealing mechanism for a multi-cylinder Stirling engine, characterized in that a notch having a taper surface with a gradually reduced diameter is provided on the machine room side at an angle of ~ 7 °.