Friction in marine engineering machinery produces abrasive particles containing valuable information. By employing oil detection technology, we can analyze these particles to monitor and diagnose mechanical system faults. This paper introduces an inductive oil detection sensor and wireless signal transmission circuit. The sensor utilizes two opposing solenoid coils of the same specifications, with the detection coil connected to a chip capacitor to form an LC resonant unit. The designed wireless transmission circuit wirelessly transmits a sensing signal from a detection coil to a receiving coil to detect metal particles in oil. This paper deduces the sensor’s inductance principle and simulates the magnetic field distribution using finite element simulation software. Through experiments, the optimal excitation frequency, coil spacing, and oil sample flow path location were determined. The sensor successfully detected 55 μm iron particles and 138 μm copper particles in a 1 mm microfluidic channel. With its simple structure, distinct signal characteristics, and high sensitivity, the sensor is suitable for detecting metal abrasive particles in hydraulic oil, providing a new approach for wireless transmission in oil detection sensors.

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.