Motor
First Claim
Patent Images
1. An electric motor comprising:
- a static part including an outer stator;
a field magnet having a cylindrical shape;
an inner rotor part having the field magnet for generating a torque around a central axis of a shaft with respect to the stator;
a bearing part for supporting the inner rotor part rotatably with respect to the static part around the central axis;
a sensor magnet that is a substantially ring-like rare earth anisotropic magnet and magnetized in multiple poles, the sensor magnet secured on the inner rotor part and arranged with the field magnet coaxially;
a flange portion of a magnetic material disposed between the field magnet and the sensor magnet, wherein the flange portion has a radially inside part, wherein the flange portion is fixed on the shaft at the radially inside part, wherein the radially inside part has a height in the axial direction, wherein the sensor magnet is fixed on the flange portion, wherein the flange portion is spaced from the field magnet with a distance more than the height; and
a sensor disposed at a radially outward portion opposed to the sensor magnet, for detecting the position of the sensor magnet.
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Accused Products
Abstract
In a motor, an sensor magnet is attached to a shaft and three Hall sensors for detecting the position of the sensor magnet are mounted on a circuit board. By using neodymium-iron-boron base rare earth magnet having radial anisotropy as a sensor magnet, the detection accuracy for the position of a field magnet via the sensor magnet by the Hall sensor can be improved.
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Citations
18 Claims
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1. An electric motor comprising:
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a static part including an outer stator; a field magnet having a cylindrical shape; an inner rotor part having the field magnet for generating a torque around a central axis of a shaft with respect to the stator; a bearing part for supporting the inner rotor part rotatably with respect to the static part around the central axis; a sensor magnet that is a substantially ring-like rare earth anisotropic magnet and magnetized in multiple poles, the sensor magnet secured on the inner rotor part and arranged with the field magnet coaxially; a flange portion of a magnetic material disposed between the field magnet and the sensor magnet, wherein the flange portion has a radially inside part, wherein the flange portion is fixed on the shaft at the radially inside part, wherein the radially inside part has a height in the axial direction, wherein the sensor magnet is fixed on the flange portion, wherein the flange portion is spaced from the field magnet with a distance more than the height; and a sensor disposed at a radially outward portion opposed to the sensor magnet, for detecting the position of the sensor magnet. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification