Design Of A New Oil Debris Sensor

Lubricating oil is an important lubricating and cooling medium for the power and transmission system of aero engine.It can take away the debris produced by the abrasion of the transmission system during the operation process of the engine.The debris often contains important information about the operation and wear condition of the engine.Therefore,research on oil detection technology for power and transmission system of aero engine is important for its fault diagnosis and prediction.Traditional off-line analysis methods such as spectroscopy and ferrography have poor real-time performance and high cost.So,it is necessary to study on-line detection technology of metal abrasive particles and develop on-line detection sensors with higher sensitivity and better stability.In this paper,based on Biot-Savart law,the mathematical model of electromagnetic solenoid sensor is established,the magnetic field characteristic of solenoid with finite length is analyzed and the basic principle of detecting metal abrasive particles by using solenoid with finite length is described.Based on the study of the influence of three-coil parallel structure on the output characteristic of the sensor,theoretical model of four-coil inner-outer structure sensor with higher detection sensitivity is proposed.The sensor model is simulated by COMSOL Multiphysics finite element analysis software.The effects of pipe radius,excitation frequency,coil length and iron abrasive radius on the output voltage are studied.Finally,according to the theoretical analysis and simulation results,four-coil inner and outer sensors are designed and fabricated.The excitation source circuit and signal conditioning circuits for the amplification,rectification and filtering of the detection signal are designed and fabricated,and the abrasive particle detection experimental system is built.The simulation model is validated by testing iron debris with different mass and collecting the output voltage of the sensor.On the basis of calibrating the performance of the experimental system with experimental data,several iron debris with different mass are selected to be measured.It is verified that the detection error of the sensor is less than 5%,which can basically meet the need of engineering application.