Abstract
Lean combustion is effective to increase thermal efficiency for gasoline internal combustion engines. This study focused on nitrogen oxides emission of homogeneous lean charge spark ignition combustion. The effect of high tumble intake port and high-energy spark ignition system on NOx emission was already shown. This paper reports analysis of cycle-to-cycle variation of NOx emission and combustion characteristics. Larger stretch of spark plasma cycle creates higher concentration NO emission. Shorter combustion duration cycle creates lower concentration NO emission. Cycle-to-cycle NO emissions on lean limit condition include less than 10ppm NO emission cycles considering NO emission by spark ignition.
