Patent ID: 7562590

Claim:
A torque detecting device comprising: a yoke assembly comprising: one set of two yoke rings each having a plurality of pole claws, the set of two yoke rings each being positioned so that the plurality of pole claws are arranged equally on an inner circumference thereof, said yoke rings including a first yoke ring having a positioning hole passing through the yoke ring in an axial direction at a position aligned with the pole claw and a second yoke ring having a positioning hole passing through the yoke ring in an axial direction at a position aligned with a space between adjacent pole claws; and a retaining cylinder made of a resin, molded integrally with the plurality of pole claws and having a pin hole extending in an axial direction, wherein said pole claws of each of said first and second yoke rings are alternatingly arranged along the inner circumference, said retaining cylinder extends fully between said first and second yoke rings and between adjacent ones of said alternatingly arranged pole claws along the inner circumference, and said retaining cylinder is integrally retained by said first and second yoke rings at a predetermined positioning to form said yoke assembly, at which the positioning holes of said first and second yoke rings and the pin hole of the retaining cylinder are connected along a common axis to form an empty, unobstructed hole; and a cylindrical magnet having a plurality of magnetic poles arranged on an outer circumference thereof, wherein said cylindrical magnet and said yoke assembly are fixed respectively to a first shaft and a second shaft connected coaxially to each other, and rotational torque applied to said first shaft and second shaft is detected based on a change in magnetic flux generated in each of said first and second yoke rings according to a relative angle displacement in a magnetic field produced by said cylindrical magnet.