MOTOR AND POWER STEERING APPARATUS

Abstract

A motor with a rearranged bearing configuration for reducing an axial length, hence dimensions thereof, is to be provided. In a motor including a stator fixed to an inner circumferential wall of a housing, a rotating shaft rotatably supported by the housing via bearings, and a rotor fixed to the rotating shaft, the rotor includes a disk-shaped portion disposed coaxially with the rotating shaft and a cylindrical portion extending parallel to the rotating shaft from a circumferential edge of the disk-shaped portion, such that the rotor constitutes a cylindrical shape with the disk-shaped portion closing an end portion. Locating a portion of the bearing and of a rotation detector inside the cylindrical portion of the rotor allows reducing the axial length of the motor.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing an outline of a structure of a motor according to a first embodiment of the present invention;

FIG. 2 is a schematic diagram showing a structure of an electric power steering apparatus including the motor according to the present invention; and

FIG. 3 is a cross-sectional view showing an outline of a structure of a motor according to a second embodiment of the present invention.

Claims

1. A motor, comprising: a stator disposed in a housing; a rotating shaft rotatably supported by a bearing secured to the housing; and a rotor fixed to the rotating shaft and provided with a magnet fixed to an outer circumferential surface thereof over an entire length thereof in an axial direction thereof; wherein a part of the bearing is located between ends of the rotor in an axial direction of the rotating shaft.

2. The motor according to claim 1, wherein the rotor includes: a disk-shaped portion disposed coaxially with the rotating shaft; and a cylindrical portion extending parallel to the rotating shaft from a circumferential edge of the disk-shaped portion, and the bearing is located radially inside the cylindrical portion.

3. The motor according to claim 1, further comprising another bearing, a part of the another bearing being located between the ends of the rotor in the axial direction of the rotating shaft.

4. The motor according to claim 1, further comprising another bearing, an entirety of the another bearing being located between the ends of the rotor in the axial direction of the rotating shaft.

5. The motor according to claim 1, further comprising a rotation detector partially or entirely disposed between the ends of the rotor in the axial direction of the rotating shaft, to thereby detect a rotational position of the rotor.

6. The motor according to claim 2, further comprising a rotation detector partially or entirely disposed between the ends of the rotor in the axial direction of the rotating shaft, to thereby detect a rotational position of the rotor.

7. A motor, comprising: a stator disposed in a housing; a rotating shaft rotatably supported by a bearing secured to the housing; and a rotor fixed to the rotating shaft and provided with a magnet fixed to an outer circumferential surface thereof over an entire length thereof in an axial direction thereof; wherein an entirety of the bearing is located between the ends of the rotor in the axial direction of the rotating shaft.

8. The motor according to claim 7, wherein the rotor includes: a disk-shaped portion disposed coaxially with the rotating shaft; and a cylindrical portion extending parallel to the rotating shaft from a circumferential edge of the disk-shaped portion, and the bearing is located radially inside the cylindrical portion.

9. The motor according to claim 7, further comprising a rotation detector partially or entirely disposed between the ends of the rotor in the axial direction of the rotating shaft, to thereby detect a rotational position of the rotor.

10. The motor according to claim 8, further comprising a rotation detector partially or entirely disposed between the ends of the rotor in the axial direction of the rotating shaft, to thereby detect a rotational position of the rotor.

11. A power steering apparatus, comprising: a steering shaft having an end to be connected to a steering wheel for exerting a steering torque thereon and another end to be connected to a steering mechanism for transmitting a steering torque modified by the power steering apparatus to the steering mechanism;a torque sensor that detects the steering torque exerted on the steering shaft;the motor according to claim 1 that provides an assisting rotational force to the steering shaft according to the steering torque detected by the torque sensor for modifying the steering torque; anda controller for accepting the steering torque detected by the torque sensor, and driving the motor based on the accepted steering torque.