Abstract
The influence on noise emissions and combustion noise level of a Diesel engine, of some engine injection parameters, as main injection timing, pilot injection timing, pilot injection duration, has been evaluated. The values of noise emissions have been measured for an in-line, four cylinders, and turbocharged FIAT 1929 cc TDI engine, using an ambient microphone, two accelerometers, and a piezoelectric sensor for the combustion pressure. An high-pressure Common Rail injection system has been used. Experimental results were processed using an ANOVA (analysis of variance) technique, to evaluate the influence of the control parameters on the controlled ones. The timing of the main injection exerts the main influence on noise, while the influence of timing and duration of the pilot injection on noise shows different behavior for different fuel injected quantities. The influence of the injection parameters on the derivative of the combustion pressure was discussed.