An Experimental Analysis on Cycle-by-cycle Combustion Variations in a Gasoline Engine

Abstract

Gasoline engines have a few too-quick combustion per a hundred cycles preventing advanced ignition timings, which eventually constraints the fuel efficiency of gasoline engine. To improve this situation, we investigated the cause of combustion variation in cycles through two experimental analyses. One is the analysis on the initial flame propagation by visualizing the inside of cylinder with a bore scope, and another analysis is on the effect from fuel and EGR gas concentrations around the ignition plug during initial flame propagation. These experimental analyses revealed that flame propagation significantly differs by each cycle, and the concentration of fuel and EGR gas do not effect on the initial flame development.