Abstract

The connecting rods employed in the reciprocating parts of general-purpose engines are manufactured from aluminum alloy, and therefore display lower material strength than steel connecting rods. In terms of operating conditions, general-purpose engines are frequently operated under high load while being held at a comparatively low engine speed, necessitating strength and durability in relation to combustion pressure. Realizing a balance between the rigidity of each part is an important factor in reconciling the achievement of weight reduction in the reciprocating parts while also maintaining strength. The research discussed in this paper developed a structure optimization system to examine shape parameters for reciprocating parts, and studied shapes that would balance the reduction of weight with the maintaining of strength. It was shown from calculation results that the annular stress of a connecting rod originates in piston pin displacement, and in order to achieve both weight reduction and strength retention, results confirmed that reducing the diameter of the piston pin and the formation of thick walls of connecting rod small-end annular sections are effective. This realizes a combination of shapes in which the stress generated on each part is equivalent to or lower than the stress generated on the mass-production shape, while reducing the mass of the piston pins by 20%. Tests were conducted on the reduced-weight shapes, and the effectiveness of this optimization system was verified.

References

1. (1) Suzuki, T., Hojo, H., Inoue, S., Moriyama, H., Fujinaga, Y.: Development of General Purpose OHC Engine with Built-in Timing Belt, HONDA R&D Technical Review, Vol.10, p.122-127 (in Japanese)
2. (2) Kawase, S., Urata, H., Ishijima, Z., Shikata, H.: Development of Powder Metallurgy Forged Ai-Si Alloy for Connecting rod, Honda R&D Technical Review, Vol.9, p.197-205　(in Japanese)
3. (3) Takasaki, M., Yoshimura, Y., Sato, K., Sugimoto, Y., Sato, T.: Development of Alloy for the High Pressure Die Casting Piston, HONDA R&D Technical Review, Vol.13, No.1, p.175-184
4. (4) Goto, T., Endo, H. : CAE Models and Optimization Technology in the Engine Development Process, Journal of Society of Automotive Engineers of Japan, Vol.67, No.5, p.56-61 (2013) (in Japanese)
5. (5) Obayashi, S., D. Sasaki, D.: Visualization and data mining of Pareto solutions using self-organizing map, Proceedings of the 2nd International Conference on Evolutionary Multi-Criterion Optimization, Springer-Verlag Heidelberg, p. 796–809 (2003)
6. (6) Koya, E., Handa, M., Yoshimoto, A., Nakagawa, M., Seto, T., Okutomi, N.: Prediction of Piston Strength by CAE, HONDA R&D Technical Review, Vol.5, p.43-50 (in Japanese)

Author (organization or company)

• Masami OKUBO（Power Products R&D Center）
• Masato SUZUKI（Power Products R&D Center）

Publication Information

Article of Honda R&D Technical Review Vol.26 No.2 (214 - 219)

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Citation Information