Wireless Temperature Sensor for Condition Monitoring of Bearings Operating Through Thick Metal Plates

This research presents the first wireless temperature sensor for bearing condition monitoring, capable of operating through thick metal (greater than 18-mm thick) plates. The sensor is a combination of a ring-shaped permanent neodymium magnet and a Hall Effect sensor. Based on the temperature-induced change in the magnetic field, the sensor is able to detect bearing temperature remotely from a distance of 40.5 mm. Additionally, temperature-induced change in magnetic field is detected at a distance of 26 mm through two 9.5-mm-thick copper, stainless steel, and aluminum plates. Furthermore, the sensor concept is experimentally demonstrated by mounting it on a commercially-available bearing and performing dynamic tests at 1500 rpm with 100-150 lb load. Maximum temperature readings for dynamic tests are in the order of 80°C -90°C, and are presently limited by the bearing test rig. However, the presented magnets are rated for operating up to 150 °C with an estimated lifetime of greater than 10000 hours in operation.