Design of a Full-Excitation Four-Coil Oil Particle Detection Sensor Based on Wheatstone Bridge

This study addresses the need for micro gear wear particle detection in lubrication systems during the operation of mechanical equipment. The traditional three-coil structure is easy to be disturbed by external noise because of the strong coupling between the excitation coil and the detection coil. Compared with the traditional three-circle structure, the symmetrical coil layout and differential signal detection mechanism can effectively offset the environmental noise, and compensate the impact of environmental changes on the detection results in real time, thus improving the detection accuracy. In addition, the bridge structure optimizes the energy transfer efficiency, reduces coil losses, and improves Q value. The detection accuracy of existing sensor structures is limited by their design, and the response to non-ferromagnetic metal particles is poor. Based on the principle of sensing oil wear particles, the analytical model of coil magnetic field is established. The principle of wear particle detection and coil quality factor are analyzed, and Wheatstone bridge structure sensor for wear particle detection is designed. The influence of composite magnetization coefficient of metal particles on the detection results was investigated by constructing the detection structure model and comparing the quality factors. The finite element magnetic field simulation is carried out, and the signal output is simulated. Through the experimental analysis of sensor data and anti-temperature interference experiment, it is proved that the detection effect is good in 80℃ environment. The detection capability level factor is introduced to complete the sensor design. The feasibility verification and analysis of the sensor structure show that under the proposed measurement standard, the detection level factor of 500μm iron particles is increased by 83.16%, that of 1000μm iron particles is increased by 31.09%, and that of 500μm copper particles is increased by 7.8 times. The structure shows strong performance in detecting small metal particles, especially non-magnetic metal particles, and provides valuable insights for on-line detection of petroleum metal wear particles.