Study Of LC Multi-Parameter Sensing For Bearings

LC-type passive wireless sensors are based on magnetic coupling principle,which can transform the measured parameters into electrical quantities,such as sensor’s resonant frequency,and detect it wirelessly through a readout coil.Moreover,LC sensor is only composed of passive components and does not need to replace the battery regularly,so it is very suitable for bearing environment monitoring.However,a typical LC-type sensor consists of only one resonant tank,and its resonant frequency can only be used to characterize a single parameter to be measured.In smart bearings,in order to monitor the health of the bearing under working conditions,it is often necessary to measure and characterize the internal temperature,stress and vibration of the bearing at the same time.Multi parameter integration is also one of the challenges faced by LC passive wireless sensor,and it is also the main research goal of this paper.The main research contents and innovations of this paper include:(1)A strain sensor for bearing environment is designed.Including a sawtooth-shaped strain gauge structure,which is made by SOI process,the size is within 5mm,and can be attached to the surface of the inner ring of the bearing.It is a capacitive strain sensor suitable for the bearing rotating environment.The use of cantilever-type fork fingers can greatly improve the sensitivity,and the fork fingers are designed into a sawtooth shape,so that the structure will not have large deformation under extremely high acceleration.Measurement results show that,under 1000με,the gauge factor(GF)of the strain sensor reaches 430 and the measured resonant frequency shows only 0.4%deviation under 1000m/s~2 centrifugal acceleration.(2)An LC multi-parameter sensing system applied to the bearing is built,which can be installed on the surface of the inner ring of the bearing.We adopt a dual-resonance circuit with Q value,and obtain three parameters by reading the real part of the impedance of the system.The system has two resonance peaks,which are used to characterize stress and vibration respectively,and the quality factor Q of the resonance peaks is used to characterize temperature,so temperature,stress and vibration can be monitored simultaneously.And a display system based on Labview is built on PC side,which can communicate with instrument and process and display data in real time.This paper focuses on the application of LC multi-parameter passive wireless sensor on bearings,and builds a dual-resonance circuit with Q value,and designs a strain sensor for bearing rotating environment.The fabricated sensor system can monitor three parameters of temperature,strain and acceleration in the simulated bearing environment.