Piezoelectric film transducer sytem for bearings

A monitoring system for in-use monitoring of a rolling element bearing in order to detect pressure waves generated in said bearing as a result of bearing damage and to detect pressure waves generated in said bearing as a result of bearing rotational speed, said monitoring system comprising:

• said rolling element bearing having a support structure and a plurality of rolling elements;
• at least two piezoelectric film transducers coupled to said support structure of said bearing on opposing sides thereof, said transducers receiving and sensing pressure waves generated by said rolling elements in said bearing, said transducers being mechanically responsive to said pressure waves generated within said bearing and said transducers being operable to output corresponding electrical signals in response to said pressure waves;
• and
• detecting means for monitoring said electrical signals and for detecting a specific pressure wave recurring over intervals of time indicative of bearing damage and for detecting a specific pressure wave recurring over intervals of time indicative of rotational speed, said detecting means including electronic circuit means for comparing an electrical signal from one of said transducers with an electrical signal from another of said transducers, said circuit operable to cancel out common background noise in said signals by subtracting said signals from one another thereby resulting in signal spikes indicative of bearing damage and rotational speed when generated.