Experimental Investigation on Condition Monitoring of Journal Bearing Lubrication Status Based on On-Rotor Sensing Signal

Condition monitoring of the lubrication status of journal bearings is essential, as lubrication plays a critical role in the stable operation of the journal bearings. In this paper, a novel on -rotor sensing (ORS) technique is used for lubrication condition monitoring of journal bearing. By mounting triaxial accelerometers directly on the shaft end, vibration signals from journal bearing with high signal-to-noise ratio (SNR) can be collected. However, due to the direct mounting of the sensor on the shaft end, the acquired vibration signals are susceptible to the influence of rotational frequency and its harmonics. In this paper, the ORS vibration signals are further decomposed using the 1-dimensional continuous wavelet transform(1-DCWT) to obtain detail coefficients that are strongly corelated with the high-frequency information. The signals that are strongly correlated with the lubrication state are reconstructed by choosing appropriate detail coefficients, and the root-mean-square (RMS) values of the signals are calculated. The RMS values are strongly correlated with the lubrication patterns revealed by the torque values of journal bearing. The experiment results show that the ORS-based technique can reveal the lubrication state of journal bearings to a certain extent.