Engine Block Vibration Measures for Time Detection of Diesel Combustion Phases

This work fits into a research program in which the multi-cylinder diesel engine block vibration signal is used with the purpose of developing and setting up a methodology able to monitor and optimize the combustion behavior by means of non-intrusive transducer.

Previously published results have demonstrated the direct relationship existing between in-cylinder pressure and engine block vibration signals in a fixed frequency band. 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, the accelerometer trace has revealed to be able to locate in the crank–angle domain important phenomena characterizing the combustion process. The aim of the present work is to extend the results presented in [9] with the final aim of establishing 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. In this paper, the previously developed steps of the research program are briefly presented. Then, the processing technique is described and the results obtained by applying a wide variation of the engine operating conditions are presented and discussed.