Patent ID: 7752923

Claim:
A magnetostrictive torque sensor for detecting a torque, comprising: an operating shaft adapted to be applied with an external torque; at least one magnetically insulating layer provided on an outer peripheral surface of the operating shaft; and at least one magnetostrictive film provided on an outer peripheral surface of the magnetically insulating layer, wherein said at least one magnetically insulating layer is formed as a hollow shaft from a nonmagnetic material, the nonmagnetic material comprising a good conductor, and said hollow shaft being pressure fitted on said operating shaft, wherein said at least one magnetostrictive film is formed by plating on an outer peripheral surface of the hollow shaft of said at least one magnetically insulating layer before said hollow shaft is pressure fitted on said operating shaft, wherein the nonmagnetic material has a lower volume resistivity than that of the magnetostrictive film and has a melting point higher than the Curie temperature of the magnetostrictive film, and wherein after the hollow shaft is press-fitted to operating shaft the magnetostrictive film is heat treated to a temperature less than its Curie temperature.