On Line Symmetrical Magnetic Excitation Monitoring Technology Of Metal Debris

Hydraulic systems and lubrication systems are widely used in industrial,civil,military and other fields.In order to accurately control the operating efficiency of mechanical equipment,the demand for online fault diagnosis during the operation of mechanical equipment is gradually increasing.The metal debris produced by wear during the operation of mechanical equipment can feedback the characteristics of mechanical equipment failure,and its online monitoring effect directly affects the operating efficiency of mechanical equipment.Aiming at the requirement of on line detection of mechanical transmission system faults,an on-line monitoring sensor for metal debris with symmetrical double-coil magnetic excitation balance magnetic field was developed based on the detection coil to obtain the magnetic field disturbance signal of metal debris passing through the magnetic excitation field.Based on the principle of electromagnetic induction,and based on the spatial magnetic field distribution of the current-carrying line element,an analytical model of the magnetic field distribution of a single-turn current-carrying ring is designed,and it is optimized as a single set of coils made of a current-carrying ring,and a symmetrical double-wire is derived.The coupled magnetic field distribution model of the coil magnetic excitation is simulated and analyzed by numerical method,and the magnetic field distribution inside the sensor is provided with a theoretical basis.Based on the mathematical model of the induction signal,the parameters affecting the metal detection sensitivity of the sensor,including inner diameter and gap,are simulated,and the optimal solution is obtained in combination with the actual use of the sensor.According to the characteristics of abrasive particle output signal,the design of dual excitation signal source,weak signal low-noise amplifier circuit,and abrasive particle signal identification module is completed,and the output signal is effectively processed to extract particle information.Taking the monitoring of metal debris in a large diameter flow channel as an example,the semi physical simulation test of metal debris with different debris sizes and materials is carried out.The experimental results show that the sensor can complete the detection of 100μm ferromagnetic metal debris and 1000μm non-ferromagnetic metal debris in the flow velocity range of 3.03～5.25m/s in an 8mm flow channel.As a metal debris detection sensor,it can also be used for metal debris monitoring of mechanical lubricants such as mechanical transmissions and engines,which is of great significance for preventing hydraulic system failures and prolonging the working life of hydraulic equipment.