Experimental investigation on the effect of multiple injection strategies on emissions, noise and brake specific fuel consumption of an automotive direct injection common-rail diesel engine

Abstract

High-pressure common-rail injection systems nowadays allow a very high degree of flexibility in the timing and quantity control of multiple injections, which can be used to obtain significant reductions in engine noise and emissions. The aim of this study is to develop a better understanding of the relationship between injection strategies and the combustion and emission formation process. Some multiple injection strategies (pilot-pilot-main and pilot-main-after) have therefore been analysed to highlight their influence on the soot, NO x combustion noise and b.s.f.c. (brake specific fuel consumption) of a passenger car direct injection diesel engine prototype. Finally, the main combustion characteristics were determined, for each operating condition, on the basis of a heat release analysis and a correlation was attempted between the combustion parameters and emissions, noise and b.s.f.c.