Simulation Analysis And Experimental Research On Oil Metal Abrasive Particle Sensor

In the combustion engine,the function of lubricant oil includes lubrication,cleaning,cooling,sealing,anti-oxidation and so on.With the operation of combustion engine,lubricant oil is also being contaminated.Among all kinds of pollutants,metal abrasive particles are extremely easy to cause the wear of combustion engine,and even cause the failure of combustion engine,so it is very important to detect metal abrasive particles in the combustion engine.Based on the principle of electromagnetic induction,an inductive metal abrasive particle sensor was designed,the main contents of this paper include:A mathematical model of the sensor for detecting metal abrasive particles was established,and the mathematical relationship between inductance conversion rate of particles' size,metal's relative permeability,coil turns of and other parameters was established.The basic structure of the sensor was designed,and two methods were introduced for the detection of metal abrasive particles.Through the simulation software of Ansoft Maxwell,the finite element simulation of the sensor was designed,including the simulation of the static magnetic field and the transient magnetic field.The simulation results showed that the variation of the internal magnetic induction in the radial direction was less than 6.8mTesla,and the variation in the axis direction was less than 11 mTesla,and the distribution of magnetic induction was symmetrical and approximately uniform;the EMF peak caused by metal abrasive particles in 50~400?m range was between 3.3248~2147.9nV;the frequency response(frequency change rate)of the sensor on ferrum abrasive particles and copper abrasive particles was-0.3694%~-0.001109% and 0.0005751%~0.1029% respectively.the grain size statistical error caused by abrasive's velocity and radial position was less than 50?m;the EMF peak was directly proportional to the number of turns of the coil,and the frequency change rate decreased with the increase of coil turns.According to the principle of the capacitance of the three-point oscillation circuit,the detection circuit of inductance sensor was designed.Based on LabVIEW software and Keysight 53230 A frequency meter which was taken as the main hardware,data acquisition system of the sensor was established.Wavelet transform was the main method of signal processing output signal of the sensor signal processing.The noise signal collected near the reference frequency could be reduced and the signal of small particles were expressed with wavelet denoising.The experimental research on the sensor was carried out,which included the metal abrasive particle calibration test and the engine oil circulation test.Metal abrasive calibration test showed that the minimum size of ferrum abrasive particles detected by the sensor was 50?m,the minimum size of the copper abrasive particles detected by the sensor was 100?m;in the ferrum calibration test,the error between test and simulation experimental results was 1.1529%~3.7413%,and in the copper calibration test,the error between test and simulation experimental results was 2.6786%~7.3904%.The circuit test of TOYOTA 8A engine showed that the data acquisition and signal processing system worked well;and the sensor could detect metal abrasive particles in the engine's lubricant,and distinguished ferrum particles and copper particles in the lubricant effectively;as the detected metal particles were in 0~150?m size range,the engine currently belonged to normal abrasive stage.