In spite of many advantages, DISI engines have some problems like difficulty in making frequent mode change between late injection and early injection smoothly and a lot of soot emissions which are maked from local rich mixtures by stratification.
Mitsubishi Motor Corporation suggested split injection strategy not only to solve those problems but also to improve full load performance. Many researchers have studied the split injection strategy but most of researches were done in condition of stoichiometric or rich mixtures.
So it was considered valuable to study the effects of split injection strategy in condition of stratified lean mixtures. This study showed the differences of combustion characteristics and exhaust gas emissions between single injection and split injection in both conditions of lean and stoichiometric mixtures with a swirl injector and in conditions of lean mixtures having different A/F ratios with a slit injector in a single cylinder DISI engine. The experimental results showed that split injection strategy could make power improvements in lean mixtures regardless of injector types and exhibited different exhaust emission characteristics from single injection.
