Magnetostriction type torque sensor

摘要

A magnetostriction type torque sensor has a magnetostrictive film formed on an outer peripheral surface of a rotary shaft, a coil having a coil centerline extending in a radial direction of the rotary shaft, and a signal processor responsive to coil impedance. Since the coil includes a coil centerline extending in a radial direction of the rotary shaft, magnetic fluxes are formed mainly in a radial direction of the rotary shaft. Accordingly, the magnetic fluxes intruding deep into the rotary shaft are decreased, and the rate of the magnetic fluxes passing through the magnetostrictive film is increased. As a result, the magnetostriction type torque sensor comes to have high sensitivity even when the rotary shaft has high magnetic permeability or high electric conductivity.