Fig.14 Improved piston drive mechanism

　

Also, this paper does not discuss manufacturing accuracy and endurance of the piston drive mechanism. A detail analysis related to mechanical loss and an endurance test is needed in the next step.

　

4.3 HERMETIC GENERATOR SET

The rotating rod seal at the output shaft has large mechanical loss as described above (see Fig.10). The seal can be omitted, if the electric generator is put in the pressurized crankcase, because the shaft does not penetrate the crankcase in that case. It is considered that the mechanical loss decreases remarkably, and the shaft power increases fairly with the hermetic generator set. Figure 15 shows the developed hermetic generator set. It was operated under light load condition. However, the measurement of the characteristics of the generator set was not done yet. Also, the electric generator shown in Fig.15 had big size, because it needed enough capacity for the experiments at wide-range speed condition. It can realize a more compact size generator set, if the engine works only at rated operation in practical use.

　

(a) Schematic view of the hremetic generator set

(b) The hermetic generator set on a test bench

Fig.15 Hermetic generator set

　

5. CONCLUSION

　

In this paper, a prototype Stirling engine was developed with purposes to get a compact and low cost Stirling engine. The prototype engine was experimented using air in atmospheric condition and with no load. Also, mechanical loss under pressurized condition was measured. It was discussed how to get higher performance based on the experimental and calculated results. As the results, it was continned that the development of higher performance heat exchangers and decreasing of mechanical loss were required.

On the other hand, it was considered that a compact Stirling engine was optimized by detailed measurements for a heat balance. As the next step, the author aims to get the target power, 50 W, and will investigate the detail of heat balance.

This research aimed at the development of a compact Stirling engine with low production cost. When the compact, low cost and high performance Stirling engine is developed, it will contribute to solution of environmental pollution and energy utilization.

　

REFERENCES

　

[1] Iwamoto, S., Hirata, K. and Toda, F.," Performance of Stirling Engines (Arrangement for Experimental Results and Performance Prediction Method) (in Japanese)", Transactions of the Japan Society of Mechanical Engineers, No. 65, Vol. 635, B, p. 361-368 (1999).

[2] Endo, N., Hasegawa, Y., Shinoyama, E., Tanaka, A., Tanaka, M., Yamada, Y., Takahashi, S. and Yamashita, I., "Test and Evaluation Method of the Kinematic Stirling Engines and Their Application Systems Used in the Moon Light Project", Proc. of 4th International Conference on Stirling Engines, p. 315-320 (1988).

[3] Hirata, K., Kagawa, N., Yamashita, I. and Iwamoto, S., "Basic Study on Development of Stirling Engine for Small Portable Generator (1st Report, Engine Design, Manufacturing and Performance) (in Japanese)", Transactions of the Japan Society of Mechanical Engineers, Vol. 64, No. 621, B, p. 1600-1607 (1998).

[4] Hirata, K., Hamaguchi, K. and Iwamoto, S., "Basic Study on Development of Stirling Engine for Small Portable Generator (2nd Report, Engine Performance Prediction by Simulation Model) (in Japanese)", Transactions of the Japan Society of Mechanical Engineers, Vol. 64, No. 621, B, p. 1608-1615 (1998).

[5] Hargreaves, G. M., "The Philips Stirling Engine", p. 130-141 (1991), Elsevier.

[6] Yamashita, I., Hamaguchi, K., Kagawa, N., Hirata, K. and Momose, Y., "Theory and Design of Stirling Engines (in Japanese)", (1999), Sankaido.

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