Design and Detection Performance of Metal Contaminant Sensor with Triple Coil Structure

In marine engineering, the daily management of mechanical equipment needs to ensure that the oil is normal. Oil plays the role of sealing, cooling, lubrication, and other functions in the equipment, and can also be used as hydraulic fluid to transfer energy. By analyzing the state of the oil, it is possible to obtain information about the operation of the equipment, such as judging the wear or failure of the equipment by detecting impurities in the oil. This paper proposes and designs a wireless triple-coil structure oil detection sensor for detecting metal particles in the oil circuit. The sensor consists of three coils placed concentrically with the same parameters. When the sensor detects metal particles in the oil, the ferromagnetic and non-ferromagnetic particles flowing through the sensor produce magnetization and eddy current effects, resulting in variable inductive signals that complete the detection of metal particles. This paper firstly explains the sensing principle of this triple coil sensor detection by formula derivation. Secondly, the simulation model of the sensor was established by using COMSOL 6.0 simulation software according to the scale of 1:1, and the magnetic field strength distribution law inside the coil of the triple-coil sensor was simulated. The experimental results showed that the sensor was able to detect iron particles at 73 µm and copper particles at 220 µm, moreover the obtained signal characteristics are obvious, with high detection sensitivity. The sensor is wireless and performs contactless detection of metal particles. This is important for the detection of metal particle contaminants in oil.