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Technology for Realization of Gasoline Engine Brake Thermal Efficiency of 45%

Article of Honda R&D Technical Review Vol.27 No.2

Summary

Seeking to achieve a brake thermal efficiency of 45% in gasoline engines, the development project discussed in this paper conducted research to increase the compression ratio in order to boost theoretical thermal efficiency and to realize an EGR technology making it possible to control knocking and reduce cooling loss.
At the same time, the basic framework of the engine was optimized in order to help realize these combustion targets. Based on the use of a long stroke to realize a stroke/bore ratio of 1.5, which is higher than that of mass-production engines, thermal efficiency was increased by reducing time loss and cooling loss through the selection of an optimal combustion chamber shape. With this engine framework as the basis, a variety of measures were applied, including the selection of an intake port shape that would enhance in-cylinder flow, the adjustment of the effective compression ratio by means of intake valve timing, control of in-cylinder fuel distribution, and high-energy sparking. These measures made it possible to realize Minimum advance for Best Torque operation at a compression ratio of 17 and stable operation at an external EGR rate of 35%, helping to enable the achievement of a maximum brake thermal efficiency of 45% in an actual single-cylinder engine.

Reference

(1) Nogawa, S., Nakata, K., Kanda, M., Improvement of Thermal Efficiency by Lean Boosted Engine, The proceedings of the 21st Internal Combustion Engine Symposium, A7-4, p.533-538 (2010) (in Japanese)
(2) Hirose, I., Kudo, H., Kihara, T., Yamakawa, M., Hitomi, M.: Introduction of SKYACTIV-G 2.0L Gasoline Engine, The proceedings of the 22nd Internal Combustion Engine Symposium, p.37-42 (2011) (in Japanese)
(3) Ogawa, H., Kimura, K., Sasaki, K., Sato, Y., Sako, T.: Performance Improvements in a Spark Ignition Gas Engine with Longer Strokes, The proceedings of the 20th Internal Combustion Engine Symposium, p.325-330 (2009) (in Japanese)
(4) Yamada, T., Takahashi, M., Ikeya, K., Takegata, N.: Intake Design for Reduction of Duration of Combustion, Honda R&D Technical Review, Vol. 27, No. 2, p. 71-79
(5) Takazawa, M., Sasagawa, T., Ohta, A., Takegata, N.: Optimization of Combustion Chamber Shape in High-efficiency Stoichiometric Combustion Gasoline Engine, Honda R&D Technical Review, Vol. 27, No. 2, p. 61-70

Author (organization or company)

Ryutaro TAGISHI(Automobile R&D Center)、Kenichiro IKEYA(Automobile R&D Center)、Masanobu TAKAZAWA(Automobile R&D Center)、Taketo YAMADA(Automobile R&D Center)

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