Electric motor and electric power steering apparatus employing the electric motor
First Claim
Patent Images
1. An electric motor comprising:
- a stator, the stator having a plurality of tooth parts, each tooth part having a radially inner side end and a radially outer side end, the radially inner side end of each tooth part having a magnetic pole portion extending in a circumferential direction and a protruded portion protruding in the circumferential direction from the radially outer side end, the magnetic pole portion and protruded portion defining a coil mounting portion wrapped by an insulating sheet;
a coil provided around each tooth part;
a yoke having a plurality of dovetail grooves extending along a radially inner peripheral surface of the yoke, the yoke containing the tooth parts and coil, the tooth parts, coil and yoke being integrated by molding using a resin having at least one of adhesion and electric insulation characteristics;
a rotor that rotates within the stator, the rotor having an outer peripheral surface; and
a plurality of permanent magnets disposed on the outer peripheral surface of the rotor, each magnet having a radially inner side surface, a radially outer side surface and a pair of opposite ends, the radially inner side surface of each magnet being curved to generally be convex in a radially inward direction and the outer peripheral surface of the rotor having a plurality of curved recess surfaces, each of the curved recess surfaces contacting the radially inner side curved surface of a corresponding magnet.
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Abstract
An electric motor has a rotor for rotation in a stator and a plurality of permanent magnets arranged on an outer peripheral surface of the rotor. A radially inner side surface of each permanent magnet is a curved to generally be convex in a radially inward direction. The outer peripheral surface of the rotor has curved recess surfaces, each of which contacts the radially inner side curved surface of a corresponding permanent magnet so that magnetic flux between adjacent permanent magnets is considerably prevented from locally concentrating within the rotor.
41 Citations
10 Claims
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1. An electric motor comprising:
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a stator, the stator having a plurality of tooth parts, each tooth part having a radially inner side end and a radially outer side end, the radially inner side end of each tooth part having a magnetic pole portion extending in a circumferential direction and a protruded portion protruding in the circumferential direction from the radially outer side end, the magnetic pole portion and protruded portion defining a coil mounting portion wrapped by an insulating sheet; a coil provided around each tooth part; a yoke having a plurality of dovetail grooves extending along a radially inner peripheral surface of the yoke, the yoke containing the tooth parts and coil, the tooth parts, coil and yoke being integrated by molding using a resin having at least one of adhesion and electric insulation characteristics; a rotor that rotates within the stator, the rotor having an outer peripheral surface; and a plurality of permanent magnets disposed on the outer peripheral surface of the rotor, each magnet having a radially inner side surface, a radially outer side surface and a pair of opposite ends, the radially inner side surface of each magnet being curved to generally be convex in a radially inward direction and the outer peripheral surface of the rotor having a plurality of curved recess surfaces, each of the curved recess surfaces contacting the radially inner side curved surface of a corresponding magnet. - View Dependent Claims (2, 3, 4)
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5. An electric motor comprising:
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a stator, the stator having a plurality of tooth parts, each tooth part having a radially inner side end and a radially outer side end; a coil provided around each tooth part, the coil being formed into a predetermined shape by being pressed using a press-forming jig; a yoke having a plurality of dovetail grooves extending along a radially inner peripheral surface of the yoke, the yoke containing the tooth parts and coil, the tooth parts, coil and yoke being integrated by molding using a resin having at least one of adhesion and electric insulation characteristics; a rotor that rotates within the stator, the rotor having an outer peripheral surface; and a plurality of permanent magnets disposed on the outer peripheral surface of the rotor, each magnet having a radially inner side surface, a radially outer side surface and a pair of opposite ends, the radially inner side surface of each magnet being curved to generally be convex in a radially inward direction and the outer peripheral surface of the rotor having a plurality of curved recess surfaces, each of the curved recess surfaces contacting the radially inner side curved surface of a corresponding magnet.
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6. An electric power steering apparatus comprising:
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an electric motor that generates a steering assisting force for supplementing a steering force; and a steering shaft that receives the steering assisting force, the electric motor including; a stator, the stator having a plurality of tooth parts, each tooth part having a radially inner side end and a radially outer side end; a coil provided around each tooth part, the coil being formed into a predetermined shape by being pressed using a press-forming jig; a yoke having a plurality of dovetail grooves extending along a radially inner peripheral surface of the yoke, the yoke containing the tooth parts and coil, the tooth parts, coil and yoke being integrated by molding using a resin having at least one of adhesion and electric insulation characteristics; a rotor that rotates in the stator, the rotor having an outer peripheral surface; and a plurality of permanent magnets disposed on the outer peripheral surface of the rotor, each magnet having a radially inner side surface, a radially outer side surface and a pair of opposite ends, the radially inner side surface of each magnet being curved to generally be convex in a radially inward direction and the outer peripheral surface of the rotor has a plurality of curved recess surfaces, each of the curved recess surfaces contacting the radially inner side curved surface of a corresponding magnet. - View Dependent Claims (7, 8, 9)
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10. An electric power steering apparatus comprising:
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an electric motor that generates a steering assisting force for supplementing a steering force; and a steering shaft that receives the steering assisting force, the electric motor including; a stator, the stator having a plurality of tooth parts, each tooth part having a radially inner side end and a radially outer side end, the radially inner side end of each tooth part having a magnetic pole portion extending in a circumferential direction and a protruded portion protruding in the circumferential direction from the radially outer side end, the magnetic pole portion and protruded portion defining a coil mounting portion wrapped by an insulating sheet; a coil provided around each tooth part; a yoke having a plurality of dovetail grooves extending along a radially inner peripheral surface of the yoke, the yoke containing the tooth parts and coil, the tooth parts, coil and yoke being integrated by molding using a resin having at least one of adhesion and electric insulation characteristics; a rotor that rotates in the stator, the rotor having an outer peripheral surface; and a plurality of permanent magnets disposed on the outer peripheral surface of the rotor, each magnet having a radially inner side surface, a radially outer side surface and a pair of opposite ends, the radially inner side surface of each magnet being curved to generally be convex in a radially inward direction and the outer peripheral surface of the rotor has a plurality of curved recess surfaces, each of the curved recess surfaces contacting the radially inner side curved surface of a corresponding magnet.
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Specification