Method and device for the non-contact measurement of torques on shafts

摘要

Prior art, problem A non-contact torque sensor is intended to be small and not to enclose the shaft. Known measuring devices comprise at least one magnetic circuit which is closed via a ferromagnetic layer on the shaft. The torque, which effects an alteration of the relative permeability of the layer, is measured by means of an inductance or of a flux density. Here, a special problem is represented by the fluctuation of the air-gap width between shaft and yoke, which makes impossible an exact measurement of the torque. Solution, invention The problem is solved in that the stray field beside the yoke is measured using at least one additional sensor element. In the case of a suitable geometry, the measured values of core field and stray field can be mutually balanced in a simple way and the torque can be determined. If at least two field coils are used, the sensitivity of the flux density sensor elements can then be calibrated during operation by means of the cyclic excitation of the coils in the same and in opposite directions, and the accuracy of the measuring arrangement can be increased.