Patent ID: 7225686

Claim:
A torque sensor comprising: a substantially tubular magnetostrictive rod having a magnetostrictive member and fixed to a stationary part at one end; a shaft passing through an inner bore of the magnetostrictive member, capable of transmitting torque to the magnetostrictive member and including a protruded part located at the other end of the magnetostrictive rod and having a larger diameter than the inside diameter of the magnetostrictive rod detecting means for detecting changes in magnetic permeability or remnant magnetization of the magnetostrictive member; and a resilient member for biasing the protruded part of the shaft toward the other end of the magnetostrictive rod, wherein torque is transmitted from the shaft to the magnetostrictive rod by a frictional force generated between the protruded part of the shaft and the magnetostrictive rod and changes in torque of the shaft are detected as changes in magnetic permeability or remnant magnetization of the magnetostrictive member based on deformation of the magnetostrictive member.