Research On Inductive Oil Wear Particle Detection Sensor

Lubricating oil is the"blood"of mechanical equipment.Wear particles are produced when gears and other components of mechanical equipment are running.These wear particles circulate in the mechanical system with lubricating oil,which cause concentration and size of wear particles increase rapidly.As a consequence,it will accelerate the aging process of equipment,which brings safety risks to industrial production.The metal abrasive particles in oil contains important information such as the location and degree of mechanical wear.Therefore,it is of great significance to monitor and study wear particles in oil for the early warning and life prediction of mechanical equipment.As a typical representative of on-line monitoring,inductive particle sensors can not only measure the size and concentration of metal particles,but also identify the properties of ferromagnetic particles and non-ferromagnetic particles.This paper focus on the problem that the measurement error of the same abrasive particle in different positions of the magnetic induction area is large which is common in the existing inductive sensors,the sensor structure of multi-planar coil in series is proposed to improve the magnetic field uniformity in the induction area so as to reduce this error.Multi-layer dense winding is used instead of single-layer plane structure to improve the magnetic field intensity and enhance the sensor's ability of particle monitoring.In order to improve the measurement accuracy of the sensor and simplify the measurement circuit,we use the inductance digital converter LDC1000 which is based on the principle of resonant frequency measurement is adopted,which greatly reduces the system cost.In this paper,the research status of oil particle monitoring and particle detection technology are introduced in detail.Secondly,the theoretical knowledge of inductive particle detection is expounded.The magnetization effect and eddy current effect of metal particles in the magnetic field of the sensor coil on the magnetic field of the coil and the coil inductance are analyzed.The principle of sensor particle strength measurement and type discrimination is studied.We designed a new sensor structure model which can improve the magnetic field intensity and magnetic field unifonnity in the induction region to solve the problem of large measurement errors in the existing inductive abrasive sensor.We use the finite element simulation software COMSOL Multiphysics to establish the sensor coil model.We analyzed the influence of the coil excitation frequency,coil ampere-turns ratio,coil diameter and other parameters on the sensor's measurement ability and resolution.The optimal parameters of the sensor were determined as 1mm pipe diameter,0.5mm coil radius,45:21:45 coil turns,0.04mm winding diameter,and 4MHz excitation signal frequency.Simulation results show that 60%of the magnetic induction area of the model is approximately uniform,and the magnetic field uniformity in the induction area is greatly improved.Finally,a real coil was made,and the experiment verified that the inductive error measured by the sensor at different positions of the same iron particle in the induction zone did not exceed 6.25%,and that the inductive error measured by the sensor at different positions of the same copper particle in the induction zone did not exceed 1.84%.