This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Effect of the Ratio Between Connecting-rod Length and Crank Radius on Thermal Efficiency
Technical Paper
2006-32-0098
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Language:
English
Abstract
In reciprocating internal combustion engines, the Otto cycle indicates the best thermal efficiency under a given compression ratio. To achieve an ideal Otto cycle, combustion must take place instantaneously at top dead center, but in fact, this is impossible. Meanwhile, if we allow slower piston motion around top dead center, combustion will be promoted at that period; then both the in-cylinder pressure and degree of constant volume will increase, leading to higher thermal efficiency. In order to verify this hypothesis, an engine with slower piston motion around top dead center, using an ideal constant volume combustion engine, was built and tested. As anticipated, the degree of constant volume increased. However, thermal efficiency was not improved, due to increased heat loss. Accordingly more experiments, which achieved a slower piston motion around top dead center by adopting a larger ratio between the connecting-rod length and the crank radius, were carried out using direct injection stratified charge combustion, which allows selective reduction of heat loss. High thermal efficiency was attained, as expected. On the other hand, an engine with a faster piston motion around top dead center, created by decreasing the ratio between connecting-rod length and crank radius, attained high thermal efficiency with quick burn premixed spark ignition combustion.
Recommended Content
Authors
Citation
Suzuki, M., Iijima, S., Maehara, H., and Moriyoshi, Y., "Effect of the Ratio Between Connecting-rod Length and Crank Radius on Thermal Efficiency," SAE Technical Paper 2006-32-0098, 2006, https://doi.org/10.4271/2006-32-0098.Also In
References
- Ikegami, M. Hamamoto, Y. Japan Society of Mechanical Engineers 83 744 109 114 1980
- Pozniak, D. J. Rydzewski, J. S. “A Study of In-cylinder Air Motion in the General Motors VOLTEC ‘TM’ 4.3 l V-6 Engine” SAE Tech Paper 850510
- Suzuki, M. Ando, R. Ishibashi, Y. “Paradoxical Approach to Improve Fuel Economy for Small Practical Motorcycle” SAE Paper 2004-01-0989
- Miwa, K. Kidoguchi, Y. Yoshikawa, D. Mohammadi, A. “Study on a New Combustion Cycle with the New Internal Combustion Engine Employing Rhombic Z-Crankshaft Mechanism” 25 30 2000
- Suzuki, M. Iijima, S. Moriyoshi, Y. Sano, M. “A Trial of Improving Thermal Efficiency by Active Piston Control -Speed Control Effect of Combustion Chamber Volume Variation on Thermal Efficiency-” SAE Paper 2004-32-0080
- Moriyoshi, Y. Sano, M. Suzuki, M. Iijima, S. “Numerical Examinations of the Effect of Active Piston Movement Control” SAE Paper 2004-32-0065
- Kume, T. Iwamoto, Y. Iida, K. Murakami, M. Akishino, K. Ando, H. “Combustion Control Technologies for Direct Injection SI Engine” SAE Paper 960600
- Nakashima, T. Saito, K. Basaki, M. Furuno, S. “New Concept of a Direct Injection SI Gasoline Engine-Part 4: A Study of Stratified Charge Combustion Characteristics by Radical Luminescence Measurement-” 2000 JSAE Annual Congress Proceedings, 20005141, No.21-00
- Morikawa, K. Kaneko, M. Moriyoshi, Y. Sano, M. “Proposition of a New Gasoline Combustion System with High Compression Ratio and High Thermal Efficiency, ‘2 nd Report An Experimental Verification and Combustion Analysis’” 2005 JSAE Annual Congress Proceedings, 20055149, No.2-05