Research on Online Synchronous Sensing Method for Debris and Moisture in Lubricating Oil

Considering issues such as limited integration, insufficient oil sample throughput, inadequate detection accuracy, and incomplete information perception, the current online oil sensors fail to meet the real-time monitoring requirements of mechanical equipment for debris size, debris type, and water content in lubricating oil. This article proposes an online synchronous sensing technology for detecting lubricating oil debris/moisture based on the principles of inductance and imaging. Additionally, an integrated detection unit comprising both inductance and moisture sensors is developed for accurate measurement of lubricating oil debris/moisture levels. The performance of the sensor was analyzed using finite element software, taking into account the influence of its structural design, excitation signal characteristics, and permalloy coating. This analysis led to the determination of optimal structural parameters. The experimental results demonstrate the effective detection capability of the sensor developed in this study for ferromagnetic iron debris larger than
$48~\mu $
m and nonferromagnetic copper debris larger than
$200~\mu $
m when applied to an 8-mm pipe diameter. Additionally, it exhibits rapid detection ability for lubricating oil with water content ranging from 0 wt% to 1 wt%. The sensor device is easy to operate, exhibits high sensitivity toward different types of abrasive materials and moisture content, and enables online synchronous sensing of abrasives and moisture.