Self-compensating magnetoelastic torque sensor system

摘要

An improved magnetic torque transducer arrangement for self-compensating effects of external magnetic sources and temperature offset comprises a shaft with at least one magnetized zone, at least one active magnetic field sensor and at least one passive magnetic field sensor disposed in such a way that active field sensor always in a position with higher magnetic field strength arise from applied torque than that of passive sensor. Passive field sensors may also be placed in both sides of the active field sensor, or on one side of active field sensor only. The transducer output is obtained by subtract the output of passive field sensors from that of active field sensor thus cancel out the effect of interfering magnetic field flux and temperature offset on the torque transducer, and partially filter out temperature sensitivity drift and rotational dependant signal. The sensitivity of active and passive field sensors can also be electrically matched by calibrating them in a uniform magnetic field, thus a completely common mode rejection can be achieved. The sensor arrangements may also be utilized in other type of sensors that extract changes in magnetic fields to indirectly detect direction, speed, presence, force, linear position, or angle to cancel out interfering magnetic field and temperature offset effect.