Many efforts are being currently devoted to the development of diagnostic techniques based on nonintrusive measurements aimed at defining the injection parameters able to optimize the combustion process.
Previous papers of the authors have demonstrated a direct relationship between in-cylinder pressure and engine block vibration signals. Besides, it was also shown sensitivity of the engine surface vibration to variation of injection parameters, when the accelerometer is placed in sensitive location of the engine block. Moreover, in the accelerometer signal, a frequency band in which such a relationship is very strict has been selected.
The aim of the present work is to establish a reliable relation between the main characteristics of the in-cylinder pressure curve and the vibration trend, by means of a deeper insight into the engine block signal. The final objective is to monitor the combustion behavior by means of a non-intrusive transducer.
In this paper, the experimental apparatus is at first described; then, the processing technique is presented and finally results are reported and discussed.