To ensure compliance with emerging Diesel emission standards and demands for reduced fuel consumption, the optimization of the engine operation is imperative under both stationary and real operation conditions.
This issue imposes a strict control of the combustion process that requires a closed-loop algorithm able to provide an optimal response of the engine system not only to warm-up, accelerations, changes in the slope of the road, etc., but also to engine aging and variations of fuel properties.
In this paper, with the final purpose of accomplishing an innovative control strategy based on non intrusive measurement, the engine block vibration signal is used to extract useful information able to characterize the in-cylinder pressure development during the combustion process.
In the previous research activity, the same methodology was applied to stationary operation of the engine. In such a condition, it demonstrated to work not only with standard diesel fuel, but also with biodiesel blends. This paper focuses on the application of the technique when the engine is operating under transient conditions.
In the research, a small displacement two-cylinder Diesel engine equipped by high pressure common rail (HPCR) fuel injection systems was used. The results of engine speed and torque transient tests are presented to highlight the reliability of the method in the optimization of the combustion process not only to obtain better engine performance, but also to reduce the smoke emissions.