Magnetically operated non-contact magnetic torque sensor for shafts

摘要

A torque sensor includes a cylindrical body disposed concentrically around a shaft and having its opposite ends secured to the surface of the shaft through elastic bodies, a layer of soft magnetic alloy having a magnetostriction property and secured to the surface of the cylindrical body, and a coil disposed concentrically around the layer with an air gap between it and the layer. The torque sensor is constructed such that a strain produced on the surface of the cylindrical body by a torque is converted into a change of a relative permeability of the soft magnetic alloy due to a reverse magnetostriction effect which is detected as a change of inductance of the coil. When the shaft thermally expands or deflects, the elastic bodies act to permit only a torque to be transmitted to the cylindrical body, so that a uniform output is provided without the influence of a thermal strain and deflection of the shaft.