Stratified Mixture Formation of Direct Injection Gasoline Engine

摘要

The effects of spray characteristics on stratified combustion in a direct injection gasoline engine have been researched. A high-performance piezoelectric (PZT) injector was used in the research, and a hole nozzle and a swirl nozzle were studied over a wide range of fuel pressures. The hole nozzle aims to form a stratified air-fuel mixture by vaporizing fuel on the piston, while the swirl nozzle forms a stratified mixture in the space above the piston, utilizing the low penetration and high dis-persibility of the spray. Both nozzles achieved stable stratified combustion. The stability depends mainly on the combination of the spray characteristics and the piston cavity. The hole nozzle requires high fuel pressure, while the swirl nozzle performs well at lower pressure. Stratified combustion demonstrates superior stability even with high-volume EGR, making it useful for reducing exhaust emissions, particularly NOx.