自在動弁系を用いた高坮縮比高効率ガソリン檆関の研究

摘要

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 IMEPn 300-650 kPa. 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 IMEPn 200 400 kPa. 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.%近年，モータリゼーションの発展とともに地球温暖rn化問題や石油枯渇問題，また大気環境汚染が深刻化しrnており，自動車用エンジンには熱効率の向上や排気エrnミッションの低減がますます求められるようになってrnいる．現在の自動車用エンジンの主流の一つであるガrnソリンSI（Spark Ignition）エンジンは，高精度な理論rn空燃比制御と理論空燃比条件下で高い浄化率を発揮すrnる三元触媒の適用により，低エミッション化が進めらrnれてきた．