Axial air gap-type electric motor
A rotor 31 has permanent magnets 31 a disposed on a surface of a disk-shaped back yoke 31 b in such a manner that long sides of each permanent magnet extend in a radial direction and that a South pole and a North pole of the permanent magnet 31 a are arranged in a circumferential direction. The four permanent magnets 31 a are equally spaced from one another in the circumferential direction, and circumferentially-opposed magnetic poles of any two adjacent permanent magnets 31 a are of the same magnetic polarity. Rotor cores 31 c of a generally fan-shape are fixed to the back yoke to generally cover the four permanent magnets 31 a. A flux barrier 31 d for reducing the short-cutting of magnetic flux of the permanent magnet 31 a is provided between any two adjacent rotor cores 31 c, and is disposed at a radially-extending central portion of the permanent magnet 31 a.
1. An axial air gap-type electric motor comprising:
a stator having a plurality of magnetic pole portions provided at a side face thereof and arranged in a circumferential direction, and
a rotor which is disposed in opposed relation to the magnetic pole portions, and is spaced a predetermined distance from the magnetic pole portions, the rotor including a plurality of rotor cores and permanent magnet groups arranged in the circumferential direction, each of the rotor cores made of magnetic material and each of the permanent magnet groups having at least one permanent magnet, wherein
the permanent magnet groups are arranged in such a manner that each permanent magnet has its magnetic polarity oriented in the circumferential direction of the rotor,
opposed magnetic poles of any two circumferentially-adjacent permanent magnet groups are of the same magnetic polarity,
an axial distance between each permanent magnet and the respective magnetic pole portion along a rotation shaft direction is longer than an axial distance between the respective rotor core and the respective magnetic pole portion along the rotation shaft direction,
the rotor includes a disk-like non-magnetic material, and
the rotor core and the permanent magnet groups are mounted on the disk-like non-magnetic material so that magnetic fluxes of the permanent magnet are directed only toward the stator.
2. An axial air gap-type electric motor comprising:
a stator having a plurality of magnetic pole portions provided at a side face thereof and arranged in a circumferential direction, and
a rotor which is disposed in opposed relation to the magnetic pole portions, and is spaced a predetermined distance from the magnetic pole portions, the rotor including a plurality of rotor cores and permanent magnet groups arranged in the circumferential direction, each of the rotor cores made of magnetic material and each of the permanent magnet groups having at least one permanent magnet, wherein
the permanent magnet groups are arranged in such a manner that each permanent magnet has its magnetic polarity oriented in the circumferential direction of the rotor,
opposed magnetic poles of any two circumferentially-adjacent permanent magnet groups are of the same magnetic polarity,
an axial distance between each permanent magnet and the respective magnetic pole portion along a rotation shaft direction is longer than an axial distance between the respective rotor core and the respective magnetic pole portion along the rotation shaft direction,
each permanent magnet includes a stator-facing surface,
at least one permanent magnet group and at least one flux barrier are located between circumferentially-adjacent rotor cores, and
each flux barrier defines a circumferential width along the stator-facing surface of the respective permanent magnet that is smaller than a circumferential width of the permanent magnet.
3. An axial air gap-type electric motor comprising:
a stator having a plurality of magnetic pole portions provided at a side face thereof and arranged in a circumferential direction, and
a rotor which is disposed in opposed relation to the magnetic pole portions, and is spaced a predetermined distance from the magnetic pole portions, the rotor including a plurality of rotor cores and permanent magnet groups arranged in the circumferential direction, each of the rotor cores made of magnetic material and each of the permanent magnet groups having at least one permanent magnet, wherein
the permanent magnet groups are arranged in such a manner that each permanent magnet has its magnetic polarity oriented in the circumferential direction of the rotor,
opposed magnetic poles of any two circumferentially-adjacent permanent magnet groups are of the same magnetic polarity,
an axial distance between each permanent magnet and the respective magnetic pole portion along a rotation shaft direction is longer than an axial distance between the respective rotor core and the respective magnetic pole portion along the rotation shaft direction,
each rotor core includes an inner peripheral surface and an outer peripheral surface, and
at least one insertion port for the permanent magnets is formed on the inner peripheral surface of each rotor core.