JPS643531A - Magnetostriction type torque sensor - Google Patents

Abstract

PURPOSE:To improve detection accuracy and to reduce the size of apparatus by providing coils for torque detection to the opposite yokes of a rotating body and detecting the direction and size of torque from a change in the magnetic permeability occurring in the torsion by the torque. CONSTITUTION:Magnetic fluxes phi are generated when excitation current is passed to the coils 22A, 22B provided to the yoke parts facing the collar part of a gear. The magnetic fluxes phi are passed only through the surface part by a skin effect and have 45 deg. angle of inclination with the radial direction of the rotating body. Torque detecting surfaces 24A, 24B on both sides have shape magnetic anisotropy. The detecting surfaces 24A, 24B on both sides have the same magnetic permeability and the electromotive forces of the coils are equaled when the torque is not applied to the gear at this time. Tensile and compressive torsions are generated and the magnetic permeability of the surfaces 24A, 24B change when the torque is applied on the gear. This change is taken out as an electric signal and the direction and value of the torque are detected. The detection accuracy is thereby improved and the size of the apparatus is reduced.