A Novel Sensitivity Improvement Method for the Electromagnetic Micro-Debris Detector Using Nanocrystalline Iron Cores

A sensitivity improvement method for electromagnetic debris detectors by adding nanocrystalline iron cores with specific structures to the sensor coils is proposed in the article. The research shows that the optimal core clearance length concentrates the magnetic field in the detector and enhances the magnetic perturbation induced by wear debris; the thinner nanocrystalline iron core for excitation coils more benefits for improving the measurement performance of the detectors since it boosts the local magnetic field in the detector and reduces the energy loss in iron cores; meanwhile, that moving the axial position of the core clearance toward the induction coil at a certain degree greatly improve the detection sensitivity of the debris detector.The experimental results show that the proposed wear debris detector with nanocrystalline iron cores can detect ferromagnetic wear particles up to about <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$60~\mu $ </tex-math></inline-formula>m in diameter, and the nonferromagnetic about <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$200~\mu $ </tex-math></inline-formula>m in diameter. Compared with the traditional debris detector without the iron cores, the amplitude of the induction electromotive force increases by approximately 42.5%.