유동 및 고주파 점화 특성이 기관성능에 미치는 영향

Abstract

Lean burn combustion became an important concept for improving fuel economy and reducing exhaust emissions. However. lean burning is associated with increased cycle-to-cycle combustion variations due t o the ignition instabilities and reduced propagation rates. Engine stability under lean mixture conditions could be improved by increasing burning rates through enhanced flow characteristics and by securing ignitability with better ignition systems. The effects of flow and ignition characteristics on the combustion performances are investigated in a 4-valve SI engine. Flow characteristics of tumble-swirl were varied with swirl control valve attached at the inlet ports. while ignition energy and its distribution were controlled in a high-frequency ignition system by changing spark duration and spark frequency. The improvement of lean burn performance by the optimum flow and ignition characteristics was discussed.