In Situ Detection of Abrasive Agglomerates Based on Phase–Amplitude Multimodal Analysis

The accurate detection of abrasive particles in mechanical equipment oil is essential for the diagnosis of equipment faults. Current research is focused on improving the detection accuracy of single particles of the sensor, with less research on agglomerated particles. This article addresses the issue of challenging inspection of agglomerated particles. A triple-coil sensor based on the digital phase-locking technique is designed to exploit the different effects of ferromagnetic and nonferromagnetic particles on the impedance characteristics of the detection coil. The digital phase lock-in technique can obtain the amplitude and phase relationship of agglomerated particles in different signal output channels. It was found that the phase of the X-value and the phase of the Y-value of the lock-in amplifier outputs were the same for ferromagnetic and nonferromagnetic particles. The experimental results show that the sensor is capable of detecting iron particles down to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$18~\mu $ </tex-math></inline-formula>m and copper particles down to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$50~\mu $ </tex-math></inline-formula>m and can achieve effective detection of agglomerated particles. The study can achieve accurate detection of oil contaminants by adopting a simple detection method, which is a good reference value for the subsequent research on high-precision detection equipment.