G0701-2-1 Study on Improvement of Combustion Characteristics of Six-stroke Diesel Engine with Common Rail System

Abstract

Six-stroke diesel engine proposed here has six processes in one cycle, i.e. intake, 1st compression, 1st combustion, 2nd compression, 2nd combustion and exhaust. By the direct EGR in the 2nd combustion process, NO emission could be expected to decrease. However, much soot was exhausted by a weak mixing in the 2nd combustion process. In the case of pre-mixed combustion with early injection in the first combustion process, NO was reduced in the first combustion and Soot was also reduced. However, the indicated torque was decreased and CO was increased. The objective of this study is to investigate the effect of compression ratio and valve timing on the characteristics of the six-stroke diesel engine. The result obtained in this study showed that reducing compression ratio caused increases of Soot and CO emission, and indicated torque decreased. Also Soot and CO emission could be reduced by delaying the valve timing.