An improved rotation angle detecting device that detects a rotation angle of a first member relative to a second member is proposed. The rotation angle detecting device includes a magnet unit fixed to the first member and a pair of magnetic sensors fixed to the second member to provide output signals whose phase is different from each other at 90 degrees in angle. The magnet unit includes a pair of disk plates that has the same magnetic poles at the same circumferential positions and is disposed at a prescribed axial distance and a shaft that is made of magnetic material to support the disk plates at the center thereof. The magnetic unit provides a uniform magnetic field in a space around the shaft between the pair of disk plates, and a pair of magnetic sensors is disposed in the space.

Rotation angle detecting device

A torque detecting apparatus according to the present invention comprises a first shaft (1) and a second shaft (2) connected coaxially to each other through a connecting shaft (3), a permanent magnet (5) fixed to the first shaft, a plurality of soft magnetic members (4a, 4b) having a collar (25) provided therein, fitted by pressing with the second shaft (2) and disposed in a magnetic field of the permanent magnet (5) to form a magnetic circuit, and a detector (6) for detecting magnetic flux generated from the soft magnetic members (4a, 4b), wherein the soft magnetic members are integrally molded with a mold body made of synthetic resin, and when a torque is applied to the first shaft or the second shaft, the torque is detected based on an output of the detector (6). The collar is made of a non-magnetic material.

Torque detecting apparatus and electric power steering apparatus

An inventive torque detection device includes: a magnetic circuit forming member having a tubular magnet provided at a first rotating body, and a magnetic ring that is located circumferentially of the tubular magnet and rotated together with a second rotating body connected to the first rotating body; a magnetic flux collecting ring part for collecting a generated magnetic flux; a detection part for detecting, based on a density of the collected magnetic flux, a torque applied to the first or second rotating body; and a molded body that is molded at an outer circumferential portion of the first rotating body, and is joined to longitudinal both sides of the tubular magnet so as to fix the tubular magnet to the first rotating body. A molding pressure, generated when the tubular magnet is molded, is applied in the longitudinal direction of the tubular magnet.

Torque Detection Device

A torque detecting apparatus detects torque applied upon a torsion bar of an electric power steering apparatus, as two sensors, which have ratiometric characteristics and have the same characteristics, simultaneously detect the amount of torsion of the torsion bar. With a gain of one of the two sensors set to the positive polarity and a gain of the other sensor set to the negative polarity, a control circuit calculates the torque applied upon the torsion bar by multiplying a difference between detection outputs from the two sensors by a predetermined coefficient. A torque detecting apparatus which is capable of detecting the torsional angle of a rotation shaft, namely, torque applied upon the rotation shaft easily and accurately using two sensors is thus realized.

Torque detecting apparatus

Device for determining a torque exercised on a shaft, wherein the shaft comprises a first shaft section and a second shaft section, wherein the two shaft sections can be rotated relative to another, with a multi-pole magnetic ring which surrounds the first shaft section and is connected thereto, and a stator holder which is mounted to the second shaft section, wherein two stator elements are mounted to a stator holder and each stator element comprises fingers projecting in an axial or radial direction which are distributed uniformly at least over part of the periphery with gaps between them, wherein the fingers of each stator element are interconnected via a magnetic flux ring, wherein the magnetic flux rings have a mutual separation and a magnetic field sensor is disposed between the magnetic flux rings, wherein at least one magnetic flux concentrator is associated with the magnetic field sensor, wherein the magnetic flux concentrator surrounds the magnetic flux rings.

Device for determining the torque exercised on a shaft

An angular position sensor is provided which is designed to an angular position of a rotary shaft. The angular position sensor has a magnet affixed to the rotary shaft. The magnet has an N-pole and an S-pole and is so geometrically shaped as to produce magnetic flux which is substantially uniform in amount within a range extending around each of centers of the N-pole and the S-pole. This improves the linearity of a change in sensor output upon rotation of the rotary shaft.

Angular position sensor working to measure high linearity magnetic flux density

A torque sensor (1) comprises: a torsion bar (4) coaxially aligned with the input and output shafts (2, 3), an annular magnet (5) attached to an axial end of the input shaft, a pair of magnet yokes (6) attached to an axial end of the output shaft and a magnetic sensor (7) for detecting the magnetic flux density generated between the pair of magnetic yokes Each of the magnet yokes is equipped with claws (6a) which are arranged with constant intervals therebetween in the circumferential direction and the number of which is equal to the N or S poles which are arranged alternately in the circumferential direction in the magnet Each claw centerline coincides with a boundary between immediately adjacent N and S poles of the magnet when the torsion bar is not rotated The magnetic sensor is inserted into an axial gap between the pair of magnetic yokes without touching the magnetic yokes

Torque sensor for electrical power steering system has elastic part between two shafts, ferromagnetic part, weakly magnetic part forming variable flux density magnetic circuit and magnetic sensor

A torque sensor has a torsion bar coaxially in alignment with input and output shafts, a ring shaped magnet fixed to an axial end of the input shaft, a pair of magnetic yokes fixed to an axial end of the output shaft, and a magnetic sensor for detecting magnetic flux density generated between the pair of magnetic yokes. Each of the magnetic yokes is provided with claws, which are circumferentially spaced at constant intervals, and whose number is equal to that of each of N and S poles alternately arranged circumferentially in the magnet. Each center of the claws coincides with a boundary between immediately adjacent N and S poles of the magnet, when the torsion bar is not twisted. The magnetic sensor is inserted into an axial gap between the pair of magnetic yokes without contacting the magnetic yokes.

Electric power steering system having a torque sensor

PROBLEM TO BE SOLVED: To provide a magnetic circuit successfully serving linearity of magnetic flux density variation for any rotation angle, and a rotation angle sensor equipped with algorithm of less rotation angle operation load by using the magnetic circuit. SOLUTION: In this device, the thickness h of a magnet 3 in the axial direction gradually decreases in a peripheral direction from a boundary section 3c between north pole 3a and south pole 3b toward the peripheral center of these two poles. Consequently, the amount of magnetic flux radially generated from any area around the peripheral center of the north pole 3a and the south pole 3b can be reduced into less than the amount of magnetic flux generated from any area around the peripheral center of the north pole 3a and the south pole 3b on the magnet 3 with circumferentially even thickness h. Thus, the amount of magnetic flux generated from any area around the peripheral center of the north pole 3a and the south pole 3b on the magnet 3 can be established as a nearly constant value. Since the rotation of this magnet 3 allows magnetic flux density variation in a gap 41 to be nearly triangular waveform, the magnetic sensor 5 can obtain output signals of better linearity. COPYRIGHT: (C)2004,JPO&NCIPI

Kenji Takeda

Papers

Angular position sensor working to measure high linearity magnetic flux density

Torque sensor for electrical power steering system has elastic part between two shafts, ferromagnetic part, weakly magnetic part forming variable flux density magnetic circuit and magnetic sensor

Electric power steering system having a torque sensor

Rotation angle sensor and rotation angle sensing device equipped therewith

Angular position pick up for measuring high linear flux density