金属颗粒形态对电感式传感器输出特性影响的研究

Research on the influence of metal particle morphology on the output characteristic of micro solenoid inductive sensor

基于电感测量技术与微流体技术的油液检测芯片,不仅可以区分出铁磁性和非铁磁性金属颗粒,还可以对油液中的颗粒进行计数统计和颗粒大小测量,从而判断金属颗粒污染物的来源及设备的磨损状态。通过理论分析、数值模拟及实验验证,分析不同形态铁磁颗粒退磁场,研究铁磁颗粒形态对电感式传感器的输出影响。建立理论模型描述不同形状颗粒的退磁因子、磁化场,以及磁化的金属颗粒产生磁场从而导致线圈电感发生变化。基于模型计算并验证同体积下球形、不同轴长比的圆柱、椭球颗粒的磁场和电感输出,分析结果显示颗粒越细长、退磁因子越小则越容易磁化,因此细长颗粒引起传感器的电感变化更大,另外圆柱形颗粒的电感变化大于旋转椭球型颗粒。

Based on the inductance measurement principle and microfluidic technology,the oil detection microfluidic chip is supposed to be used to distinguish the ferrous and non-ferrous metal particles. Meanwhile,the source of the metal particles and wear condition of the equipment can also be evaluated through counting the number and measuring the size of the particles in the oil. Concerning about the particle morphology,through related theoretical analysis,numerical simulation and experimental verification,this paper analyzes the magnetization field of the ferrous particles with different morphologies,studies the influence of the ferrous particle morphology on the output of the inductive sensor,and establishes the mathematical model to describe the change of the imaginary part of impedance（ inductance） caused by the magnetic flux density,the demagnetizing factor and the magnetic field generated by different wear particle morphologies. The magnetic field distribution and the coil inductance generated by several kinds of spherical,ellipsoidal and cylindrical metal particles with same volume were obtained based on theoretical calculation and verified by experiment. Analysis results conclude that high magnetization intensity and large changing rate of coil inductance are obtained for slender wear debris and lower demagnetization factor because the metal particles are easier to be magnetized. And the inductance change caused by cylindrical metal particle is higher than that caused by ellipsoidal metal particle.