Online Monitoring of Engine Oil Quality Based on AE Signal Analysis

This paper studies online condition monitoring of engine oil by analysing the acoustic emission (AE)
signals. The AE signals were measured using an AE sensor mounted on the thrust side between second and third cylinders in a four cylinder diesel engine. The signals were then filtered and
transformed to the frequency domain, where the amplitudes of the different frequency components of the AE waveforms were analysed and compared to the AE baseline signatures. The mean amplitudes
of the spectral components in the frequency band 10kHz to 50kHz were found linearly proportional to
the engine speed and load. It was also found that the RMS values of this frequency band were
affected by the oil viscosity. These results show that it is possible to use AE measurement to predict the quality of lubrication.