Patent ID: 8915150

Claim:
A torque sensor comprising: a torsion bar for coaxially coupling between a first shaft and a second shaft and for transforming a torque applied between the first shaft and the second shaft into a torsional displacement: a multi-pole magnet fixed to the first shaft or one end side of the torsion bar and having a plurality of N pole and a plurality of S poles magnetized alternately along a circumferential direction of the multi-pole magnet at every predetermined magnetizing angle; a pair of yokes fixed to the second shaft or the other end side of the torsion bar, disposed on an outside of the multi-pole magnet in a radial direction of the multi-pole magnet, facing each other with a gap in an axial direction of the multi-pole magnet, and providing a magnetic circuit in a magnetic field generated by the multi-pole magnet; and a pair of magnetic sensors arranged along the circumferential direction, wherein: each magnetic sensor includes a magnetism sensing part for detecting a magnetic flux density generated in the magnetic circuit; each magnetic sensor outputs a detection signal detected by the magnetism sensing part to an external computing device; the pair of magnetic sensors output the detection signals to the external computing device in such a way that the computing device calculates a sum of outputs or a difference of outputs of the pair of magnetic sensors so as to cancel a variation of the outputs produced by a magnetic flux generated from the multi-pole magnet and directly reaching the magnetism sensing parts; the pair of magnetic sensors are arranged in such a way that an angle interval between the magnetism sensing parts is equal to or odd number times larger than the magnetizing angle of the multi-pole magnet, and the magnetism sensing parts are arranged at a same height from the one end side of the torsion bar in the axial direction; and the pair of magnetic sensors output the detection signals to the computing device in such a way that the computing device computes the sum of the outputs of the pair of magnetic sensors.