TORQUE SENSOR AND MOTOR-DRIVEN POWER STEERING DEVICE EQUIPPED WITH THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a torque sensor 1 whose structure is simple, which does not have an electrical contact part and whose accuracy is satisfactory near a neutral point. SOLUTION: The torque sensor 1 is constituted of a torsion bar 4 which connects an input shaft 2 and an output shaft 3 on the same axis, a ring-shaped magnet 5 which is attached to the end part of the input shaft 2, one set of magnetic yokes 6 (6A, 6B) which are attached to the end part of the output shaft 3 and magnetometric sensor 7 which detects the density of magnetic fluxes generated in the magnetic yokes 6. In the magnetic yokes 6, claws 6a whose numbers (12 pieces) are equal to those of N-poles and S-poles of the magnet 5 are installed at equal intervals on the whole circumference. The magnetic yokes 6 and the magnet 5 are arranged in such a way that centers of the claws 6a installed at the magnetic yokes 6 agree with boundaries between the N-poles and the S-poles of the magnet 5 in a state that the torsion bar 4 is not twisted. The magnetometric sensor 7 is inserted into a gap installed between the magnetic yoke 6A and the magnetic yoke 6B facing in the axial direction so as to detect the density of the magnetic fluxes.