Triple-Coil Inductive Debris Sensor with Special Shielded Coils for Depressing Interference of Dielectric Components

摘要

Dielectric contents, such as air bubbles and water droplets in the lubricating oil, can severely interfere with the performance of inductive debris sensor due to the effect of coil parasitic capacitance. This study proposes a special mesh screen that can effectively eliminate the interference to a triple-coil inductive sensor to avoid false alarms and increase productivity. Experimental results show that the sensor can detect 353μm (D) ferrous particles and 706μm (D) nonferrous particles in a pipe with a diameter of 50 mm. Comparison experiments indicate that a water droplet with a volume of 697 mm3can generate an interference signal equivalent to that of a ferrous particle with a diameter of 560μm for the sensor without screen, while no interference is generated for the sensor with the screen.