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Description
The design and implementation of a contactless pressure and temperature measurement system for an automotive brake assembly, utilizing glass-coated magnetic microwires, is presented. Amorphous microwires, produced by the Taylor-Ulitovsky method, possess distinctive magnetic characteristics - most notably, magnetic bistability, a pronounced Barkhausen jump, and the influence of pressure on the value of the critical switching field. These properties facilitate the detection of pressure and temperature changes through corresponding shifts in the critical switching field, which are measured by a dedicated pickup coil.
The experimental set-up consists of genuine brake components (including a brake master cylinder, brake booster, brake lines, and a brake caliper with a rotor) rigidly mounted to a support structure. Two coils (an excitation coil and a pickup coil) are employed. The excitation coil generates a triangular AC magnetic field that provokes the microwire’s magnetization reversal, while the pickup coil records the resulting voltage impulses. Pressures of up to 60 bar were applied and monitored, and the brake fluid temperature was altered by an external heating mechanism to assess the microwire’s response to thermal changes.
The measured dependences confirm that glass-coated microwires can reliably track changes within the brake system without the need for direct modification of the hydraulic assembly. This technology thus holds potential for high-accuracy and safe measurement of pressure and temperature in automotive applications, particularly where contactless sensing and robust performance under mechanical stress are essential. In addition, the results outline several areas for further research, such as improving sensor sensitivity and minimizing interference from external magnetic fields in real-world environments.
