The identification of piston-cylinder clearance using time-frequency methods

A fault recognition technique for the internal combustion engines using time-frequency representations of vibration signal has been presented in this paper. Engine block vibration results as a sum of many excitations mainly connected with engine speed and their intensity increases with the appearance of a fault or in case ofhigher engine elements wearing. In this paper an application of acceleration signals for the estimation of the influence of piston skirt clearance on diesel engine block vibrations has been described. Engine body accelerations registered for three simulated cases representing piston skirt clearance variations were an object of preliminary analysis. The presented procedures were applied to vibration and pressure signals acquired for a 0.5 dm3 Ruggerini, air cooled diesel engine. reciprocating machines are difficult to diagnose using traditional frequency domain techniques due to the fact they generale transient vibrations. In the experiments that were conducted Gabor Analysis and Adaptive Spectrogram has been chosen The Gabor spectrogram is a powerful tool for on-line monitoring and diagnosis of combustion process. There are important features of the vibration signal that are sensitive to the change of IC engine condition. For that reason the DWT transform was applied. Based on the results, authors propose detection and piston skirt clearance monitoring algorithm.