Method for producing a magnetostrictive torque sensor, and an electric power steering system

摘要

PROBLEM TO BE SOLVED: To provide a method for manufacturing a magnetostrictive torque sensor in which signal amplitude of the detected torque does not shift even under operating environment temperature.;SOLUTION: This is the method for manufacturing the magnetostrictive torque sensor 3 for detecting torque applied to a shaft 21 by electrically detecting distortion of magnetostrictive films 3a and 3b prepared on surface of the shaft 21, which includes a plating process to form these magnetostrictive films 3a and 3b on surface of the shaft 21 by plating, and a heat treatment process to heat treat the films 3a and 3b. This heat treatment process further includes a process for conducting heat treatment to eliminate desorption of a first mode hydrogen contained in these films 3a and 3b which has peak of hydrogen desorption at about 120°C. In such a collateral heat treatment process, time and temperature for heat treatment are defined as to make the desorption quantity of the hydrogen desorbed in the heat treatment process equal to the desorption quantity of hydrogen heat-treated at 110°C for 400 hours.;COPYRIGHT: (C)2010,JPO&INPIT