Research On Magnetic Core Type Eddy Current Sensor For Detecting Metal Abrasive Particles In Oil

As a typical representative of detecting abrasive particles in hydraulic oil,eddy current sensors have the advantages of simple structure,low production cost,and detailed wear particle information,etc.,which have attracted widespread attention.However,the detection sensitivity of the eddy current sensor is still relatively low,and the stability and reliability of the sensor need to be improved in practical applications,which restricts its further application in the online monitoring of equipment health.Aiming at the problems of too small diameter of the flow channel of the eddy current sensor,low oil throughput and edge effects,this paper designs and develops a magnetic core type eddy current detection sensor.Use a double-layer planar coil parallel structure to improve detection sensitivity;an external magnetic core enhances the magnetic flux density in the detection area to improve the impact of edge effects;design a new microfluidic structure to increase oil throughput,and the detection principle,detection system parameters,and magnetic field uniformity have been studied:(1)A magnetic core eddy current sensor is designed and its detection principle is introduced.The sensor is simulated using COMSOL software to verify the effect of edge effects.(2)The mathematical expressions of the inductor coil change rate of the four structures are deduced,and the optimal structure of the magnetic core eddy current sensor coil is determined.(3)The effects of the excitation signal(frequency,voltage),coil parameters(wire diameter,number of turns,and layers)and metal abrasive particles(particle size,position)on the detection performance of the core-type eddy current sensor were obtained through simulation;The optimal value range of each parameter of the detection system.(4)Set up an experimental platform and design an experiment to detect and extract inductance parameters of abrasive particles with different attributes.(5)Analysis of simulation and experimental results.The results show that the magnetic core eddy current sensor improves the detection performance;the relationship between the particle size of the abrasive particles and the change rate of the coil inductance is obtained;the lower detection limit of the metal abrasive particles by the sensor is determined.The magnetic core eddy current detection sensor designed in this paper realizes the differential detection of metal abrasive particles.The effects of sensor coil parameters,abrasive particles and excitation signals on the change rate of the magnetic core eddy current sensor coil inductance are simulated.Compared with the traditional eddy current sensor,this sensor improves the impact caused by edge effects,improves the accuracy of abrasive particle detection,increases oil throughput,and avoids the occurrence of pollutant deposition and blockage in the flow channel..The experimental results show that the magnetic core type eddy current detection sensor can detect iron abrasive particles with a particle size of 30 ?m and copper abrasive particles with a minimum particle size of 30 ?m when the double-layer coil has 30 turns and the oil throughput is 50 ml/min.