Abstract
In this paper, Discrete Wavelet Transform (DWT) was applied to detect the abnormal combustion and mechanical exciting forces in the internal combustion engine using the vibration acceleration waveform of the engine block. The difference of the wavelet components between the normal and abnormal condition was extracted to examine the timing of the generation of the abnormal exciting force. This method was applied to the two cases of the four cylinder diesel engine; one is the increasing of the combustion pressure and another is the increasing of the clearance between the cylinder liner and piston in the specified cylinder. The calculated results of the difference of the wavelet components in these two cases showed the distinct abnormal event timing and the availability of this method were confirmed.
