Abstract
In diagnosing bearings, acceleration or eddy-current sensors is frequently used. However, sometimes there are objects to which the sensors cannot be applied because of their structures and the cost to be spent. As such an object, there is a sump pump used in a waste liquid transportation in nuclear power plants, where the shaft is put in the waste liquid.
The paper proposes a signal propagation model based diagnosis method which monitors the anomaly of the bearing indirectly by measuring the shaft vibration. The vibration measurement is achieved by using an ultrasonic sensor attached on the casing surface with a magnet, so that the system serves as a portable unit which can reduce the monitoring cost remarkably. The effectiveness of the method is demonstrated with simulations and an experiment.
