Wireless Method for Measuring the Rotational Speed of Roller Bearing in a High-Temperature Environment

Abstract

Roller bearings are important rotating components of engines and have been widely used in the commercial, aerospace, railway transportation, and military fields. The inner race of a bearing that operates at high speeds can attain a temperature of almost 200 °C. Therefore, accurately measuring the speed of bearing inner race under a high-temperature thermal load is vital to ensure that engine is working properly. Herein, we propose a wireless method for measuring the bearing speed. The proposed method has a higher temperature application range and better accuracy than previous used methods. It measures the bearing’s inner race speed based on the eddy current effect and impedance matching. Adding a silver/copper layer to the surface of the bearing substrate changes its conductivity, magnetic permeability, and the equivalent impedance of the antenna. After passing through the coupler and detection circuit, the signal is output to the oscilloscope as a periodic voltage. The rotational speed of the bearing’s inner ring is measured by calculating the periodicity of the waveform. A bearing speed test platform is built and used for multiple groups of bearing speed measurements at 20 °C, 100 °C, and 200 °C on the platform. The results indicate that the method provides excellent stability and accuracy in the range of 0–1000 rpm, with a stable relative error of less than 1.64% and a maximum hysteresis of 1.72%. The maximum repeatability is 1.63658% (1000 rpm, 200 °C), and the maximum uncertainty is 0.66782 (1000 rpm, 200 °C).