Ferromagnetic Metal Particle Detection Including Calculation of Particle Magnetic Permeability Based on Micro Inductive Sensor

摘要

As the working medium of machine, lubrication oil system is a very important component, which can be used to judge the operating conditions ofmachine, moreover, lubricating oil detection can eliminate the need for costlymachine shutdowns for inspection. Metal particle is themost important parameter in lubrication oil detection. Inductance detection is one of the commonly used metal particle detection methods, with the development of micro fabrication technology, which can measure the sizes of metal particles and count the particles. In this paper, the model of ferromagnetic metal particle detection is established based onmicro inductive sensor. It is obtained that the inductancechangerate is proportional to the magnetic permeabilityof themetal particle and the cube of the particle size ofmetal particle. The tests about themetal particleswith five different diameters are carried out, it is obtained that the theoretical values are in good agreement with the experimental values, the relative errors are less than 9.47%. And combined with experimental research, the magnetic permeability of ferromagneticmetal particles mu 3.907x10(4) H/m, 4.246 x 10(4) H/m, 4.092 x 10(4) H/m, 3.718 x 10(4) H/m, 4.07 x 10(4) H/m and 4.4289 x 10(4) H/m is obtained when the radii of particles are 25 mu m, 50 mu m, 100 mu m, 200 mu m, 500 mu m and 1 mm, the relative errors E-r = |1- mu/mu(AVG)| are less than 8.82%.