소형 디젤엔진에서 분사전략이 나노입자 배출 특성에 미치는 영향

This research aims to investigate the characteristics of regulated emissions such as particulate materials and vehicle performance by variations of injection strategy and control of air quantity affecting on combustion conditions in a compact diesel engine. In this experiment a 3.0 liter high speed diesel engine is used equipped with CRDI fuel injection system where the injection pressure is 160㎫ and E-VGT is applied. In order to investigate exhaust emissions and variations of power due to injection strategy, main and pilot injection are changed and compared with their engine performance and amounts of emissions which are obtained by a conventional ECU. From the results, the characteristics of torque tend to decrease when the number of injection times increases but the torque increases as air fuel ratio increases, but the torque decreases due to increased back pressure specially in lower engine loads. The nano-particle is not affected by the variation of air-fuel ratio but the amount increase as the number of pilot injection time increases and engine load is lower, and similar emission characteristics are shown both in ranges of low and high speeds. PM emission emitted more in lower engine speed or higher load, and pilot injection gives disadvantage on PM emission since PM increase when the number of pilot injection time increases, but the reduction effect is appeared apparently due to the increase of air quantity. NO X emission increases in accordance with increasing air-fuel ratio in overall ranges but the reduction rate is very effective by pilot injection.