自在動弁系を用いた高圧縮比高効率ガソリン機関の研究(熱工学,内燃機関,動力など)

概要

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An application of variable mechanisms and novel combustion technologies to a gasoline engine will be a solution to improve its thermal efficiency. The authors performed an experimental study to improve indicated thermal efficiency using an experimental engine with variable valve trains and high compression ratio. High efficiency SI (Spark Ignition) operation was achieved by reducing pumping loss as much as possible and using a high geometric compression ratio. High efficiency SI operation enabled about 10% improvement of indicated thermal efficiency to a conventional SI engine in a range of IMEP_n 300-650kPa. However, the improvement ratio fell with decreasing the engine load. HCCI (Homogeneous Charge Compression Ignition) is a promising operation and possible for this engine utilizing these variable mechanisms effectively. HCCI enabled about 30% improvement of thermal efficiency in a range of IMEP_n 200-400kPa. Furthermore, the improvement ratio was kept high even in the low load. These two operations have quite low pumping loss, but it was revealed that HCCI is a superior cycle in thermal efficiency thermodynamically. The reasons were examined by 0-D cycle simulations.
2008-10-25