A Passive Ferro-Particle Sensor of Lube-Oil Based on Single Permanent Magnetic Ring

Inductive particle sensors have been widely used in wear monitoring for mechanical equipment, in which magnetostatic inductive sensor is the preferred choice to detect ferro-particles. However, the existing magnetostatic inductive particle sensors contain iron core components, and most of them are driven by external power supply, which makes it difficult to achieve lightweight and vulnerable to electromagnetic noise. Accordingly, this paper proposes a passive ferro-particle sensor of lube-oil based on single permanent magnetic ring. The corresponding mathematical model is established, and the analytical expression for the ferro-particle induced voltage is derived. To verify the validity of the model, the modeling results are compared with the finite element analysis. And the influence of the relevant parameters of the permanent magnet ring and coil on the induced voltage is discussed. The experimental results indicate that $30\mu $ m ferro-particles can be detected by this sensor at an oil flow rate of 510 ml/min. By comparing with the existing sensors, it can be concluded that the proposed sensor is of great significance to improve lightweight design and high-precision sensing for online ferro-particle monitoring in lube-oil.