1/4 포트마스킹이 엔진의 부분부하 성능에 미치는 영향

To securing basic data for intake port design, effects of a masking on the part load performance were investigated in a SI engine. For this purpose, 3 kinds of masking, which have different shapes is applied to the engine intake system. The characteristics of the performance were estimated though mixture response test at various engine load and speed. The results show that lean misfire limits is expanded considerably and fuel consumption is improved and Nox emission increases in spite of retarded spake timing due to the stratification which is caused by unequal flow distribution between the two intake ports. The mechanism of stratification by masking is different from axial stratification, and the fuel entering though masked port plays a very important role in this stratification process. In conclusion, the port masking method could be easily applied to engine intake system and be very effective for inducing the stratified charging without the change of port design.