Patent ID: 7568400

Claim:
A torque detecting apparatus comprising: a first shaft and a second shaft joined coaxially to each other; a cylindrical magnet arranged for rotating together with the first shaft; a pair of yoke rings arranged for rotating together with the second shaft in a magnetic field induced by the cylindrical magnet; a pair of magnetism collecting rings arranged to surround the two yoke rings respectively from the outer side; and a magnetic sensor disposed between two opposite magnetism collecting projections provided outwardly on the outer side of the magnetism collecting rings respectively, wherein a torque exerted on the first and second shafts is detected from the density of the magnetic flux induced between the two opposite magnetism collecting projections and measured by the magnetic sensor, the magnetism collecting projections are arranged at two or more locations on the circumference of each of the pair of magnetism collecting rings, the magnetism collecting projections being directed substantially in parallel with each other, and the magnetic sensors are disposed between the corresponding pairs of the magnetism collecting projections.