Development Of On-line Detection System For A Certain Type Of Aero-engine Oil Metal Debris

As the core component of the aircraft,the aero-engine is critical to ensuring flight safety.Common wear-type faults are one of the main cause of engine failure.The detection of metal debris in the oil can be used to monitor the wear state of the aero-engine.Compared to offline detection,Metal debris on-line detection technology has the advantages of continuous,real-time and comprehensive.The foreign products of aero-engine metal debris on-line detection are expensive and technically blocked,and no mature products are used widely in China.Therefore,The on-line detection system of aero-engine oil metal debris is developed based on on-line detection technology in this paper,which is quite significant.The online detection system designed in this paper consists of three parts: metal debris sensor,signal processing device and upper computer.The magnetic field distribution of a single current-carrying circular wire and a long straight solenoid is derived by Ampere's law and Biosval's law,and then the established sensor mathematical model was analyzed.The software maxwell was used to simulate the static and transient magnetic field distribution of the excitation coil and the whole set of coils in the three-helical coil,verifying the conclusion of theoretical analysis and providing a more reliable theoretical basis for sensor design.Referring to the MetalSCAN sensor,a two-output sensor structure formed by two sets of three-helical coils wound on the same inert tube was proposed,and the resonance component was selected to frequency-selectively amplify the output signal.In this paper,the sensor was designed in detail,including structural parameters and material selection.The structure of the metal debris detecting device is two parallel PCB boards,which are integrated in the aviation chassis to ensure the structural strength and stability while taking into account the volume and weight.Anti-jamming technology was used in the process of designing each module circuit of the metal debris detecting device.In order to ensure the normal operation of the sensor and each circuit,an amplitude and frequency stable excitation sinusoidal signal generating circuit and an EMI power supply filtering circuit were designed.According to the characteristics of the signal,signal processing circuit was designed,including preamplifier conditioning module,detection module,amplification filter module,digital processing module circuit.Combined with the system design of the upper computer and the lower computer,the whole system initially realized the online detection of metal debris in the aviation engine oil.The lower computer software accomplished the mission of configuring the excitation signal generating circuit,AD sampling,identifying the metal debris end algorithm and transmitting data,and the upper computer software realized the function of reading the serial port data and displaying it.As the metal debris material,bearing steel and 62 copper were used in the experiment,and the vibration comparison experiment is added to verify the system function.The results show that the system can detect and display the size,number and properties(ferromagnetic and non-ferromagnetic)information of metal debris in real time.The detection resolution of ferromagnetic debris is 0.125 mm,and the detection resolution of non-ferromagnetic debris is 0.45 mm.The innovation is the structure of the traditional inductive sensor is improved,a dual output structure is proposed,which can reduce the sensor noise and increase the sensitivity by adding the resonant component in this paper.The metal debris detecting device circuit is design reasonably to reduce the circuit noise,which can improve the system metal debris detection capability further,the system has a certain engineering reference value on the aspect of metal debris online detection.