2003 年 69 巻 686 号 p. 2376-2381
Fuel injection system and mixture formation for direct injection gasoline engine has been studied. Stratified mixture formations with tumble air motion showed better fuel economy and cleaner exhaust emission compared with wall guide system. In this report, combustion stable area of stratified condition with tumble air motion was analyzed experimentally. Mixture visualization results showed combustion stable area has relation with timing of combustible mixture around spark plug. Fuel injection method was proposed ; combustion stable area to be expands by reducing spray speed and introducing fuel-air mixture to a plug twice by injection control which divides injection into 2 times.