Torque detector and electric power steering system including the torque detector

摘要

A torque detector includes a permanent magnet, a pair of magnetic yokes, and a magnetic sensor. The magnetic yokes include a first magnetic yoke and a second magnetic yoke. The first magnetic yoke has a first ring and a plurality of first teeth extending from the first ring in an axial direction. The second magnetic yoke has a second ring and a plurality of second teeth extending from the second ring in the axial direction. The first teeth extend in the axial direction beyond the second ring of the second magnetic yoke. The second teeth extend in the axial direction beyond the first ring of the first magnetic yoke.

主权项

1. A torque detector comprising:
a permanent magnet attached to one of an input shaft and an output shaft that are connected to each other by a torsion bar so as to be rotated relative to each other in response to torsion of the torsion bar, and magnetized in a circumferential direction of the torque detector; magnetic yokes including a first magnetic yoke having a first ring disposed around an outer periphery of the permanent magnet and a plurality of first teeth extending from the first ring in an axial direction of the torque detector, and a second magnetic yoke having a second ring disposed around the outer periphery of the permanent magnet so as to be opposed to and apart from the first ring in the axial direction and a plurality of second teeth extending from the second ring toward the first ring in the axial direction, the first teeth and the second teeth being alternately arranged in the circumferential direction, and the magnetic yokes being attached to the other one of the input shaft and the output shaft so as to be located in a magnetic field created by the permanent magnet; and a magnetic sensor that detects a magnetic flux density of a magnetic circuit formed of the permanent magnet, the first magnetic yoke and the second magnetic yoke, wherein the first teeth extend in the axial direction beyond the second ring, and the second teeth extend in the axial direction beyond the first ring.