Multi-point bearing cage wireless temperature sensor

In this article, a multi-point bearing cage wireless temperature sensor for mechanical health monitoring applications is presented for the first time. Two insulated inductive coils and two temperature sensitive capacitors are attached along the circumference of the cage. The resonant frequencies of these LC circuits shift linearly with temperature as sensed by the capacitors. An interrogator coil placed axially at 3-mm distance is then able to detect the individual resonant frequencies corresponding to a localized temperature sensed by the individual capacitors on the cage. This allows the user to have a more detailed knowledge of the temperature profile along the bearing circumference and allows the detection of localized faults caused by defects such as shaft imbalance, misalignment, and spalls on individual balls.