배기가스재순환 및 분사방법이 직접분사식 가솔린엔진에 미치는 영향

Abstract

By applying EGR(Exhaust Gas Recirculation) to DISI(Direc-injection spark ignition) engine, the level of NOx is decreased by the dilution effect of mixture. However, the level of THC is increased and the engine performance is decreased. Split injection technique is known to have effects on decreasing THC levels and increasing performance at high load condition but do not have a positive effect on NOx emission level. This shows that the simultaneous application of split-injection and EGR makes the expectation of the improvement in emission level and engine performance compared to the situation of single-injection with EGR and non-EGR cases. The characteristics between single-injection and split-injection techniques with EGR were investigated with various EGR rate and air-fuel ratios at optimal injection and ignition timings. The relations between combustion characteristics and exhaust emissions were also considered. The results showed that the split injection with EGR could make better emission characteristics and engine performance than the single injection with EGR at air-fuel ratio of 24.