Rotor, stator and motor
A rotor with four axially stacked rotor cores, and a plurality of field magnets interposed between them. Each rotor core includes a rotor-side claw-shaped magnetic pole. Each rotor-side claw-shaped magnetic poles are respectively extending from and formed on each rotor core at equal angle intervals. Tip end surfaces of the first and third rotor-side claw-shaped magnetic pole abut against or are closely opposed to each other axially. Tip end surfaces of the second and fourth rotor-side claw-shaped magnetic poles abut against or are closely opposed to each other in the axial direction. The plurality of field magnets are magnetized in the axial direction such that the field magnets causes the first and third rotor-side claw-shaped magnetic poles to function as first magnetic poles, and cause the second and fourth rotor-side claw-shaped magnetic poles to function as second magnetic poles.
1. A motor comprising:
a shaft extending along an axial direction of the motor;
a rotor including a first rotor core having a plurality of first rotor claw-shaped magnetic poles arranged at equal intervals from one another in a circumferential direction of the motor, a second rotor core having a plurality of second rotor claw-shaped magnetic poles arranged at equal intervals from one another in the circumferential direction, and an annular field magnet placed between the first and second rotor cores and magnetized in the axial direction, the first and second rotor claw-shaped magnetic poles being alternately placed in the circumferential direction, and the field magnet is configured so as to cause the first and second rotor claw-shaped magnetic poles to function as magnetic poles which are different from each other; and
a stator including a first stator core having a plurality of first stator claw-shaped magnetic poles arranged at equal intervals from one another in the circumferential direction, a second stator core having a plurality of second stator claw-shaped magnetic poles arranged at equal intervals from one another in the circumferential direction, and a coil portion placed between the first and second stator cores and wound in the circumferential direction, the first and second stator claw-shaped magnetic poles being placed alternately in the circumferential direction and being opposed to the first and second rotor claw-shaped magnetic poles, and the coil portion is configured so as to cause the first and second stator claw-shaped magnetic poles to function as magnetic poles which are different from each other based on energization to the coil portion, and cause polarities of the first and second stator claw-shaped magnetic poles to switch to each other, wherein
the shaft extends through one of the rotor and the stator,
the first and second rotor cores and the first and second stator cores have an equal number of claw-shaped magnetic poles,
each of the plurality of first and second stator claw-shaped magnetic poles includes a radially extending base portion and a plurality of axially extending magnetic pole pieces, the magnetic pole pieces including a central magnetic pole piece and side magnetic pole pieces, the central magnetic pole piece being located at a circumferentially central position of the claw-shaped magnetic pole, the side magnetic pole pieces being located at opposite sides of the central magnetic pole piece in the circumferential direction,
each of the central and side magnetic pole pieces includes a flat inner surface portion and a flat outer surface portion, the flat inner surface portion of the central magnetic pole piece facing toward a rotation axis of the motor, the flat inner surface portions of the side magnetic pole pieces extends parallel to the flat inner surface portion of the central magnetic pole piece, the flat outer surface portion of the central magnetic pole piece facing away from the rotation axis of the motor, the flat outer surface portions of the side magnetic pole pieces extend parallel to the flat outer surface portion of the central magnetic pole piece,
the central and side magnetic pole pieces are arranged to be a staircase pattern along the circumferential direction so that the flat inner surface portion of the central magnetic pole piece is located radially further from the rotation axis of the motor as compared to the flat inner surface portions of the side magnetic pole pieces and the flat outer surface portion of the central magnetic pole piece is located radially further from the rotation axis of the motor as compared to the flat outer surface portions of the side magnetic pole pieces in each of the first and second stator claw-shaped magnetic poles.
2. The motor according to claim 1 , further comprising a non-magnetic portion arranged between the field magnet and the first and second rotor claw-shaped magnetic poles, wherein the non-magnetic portion positions the field magnet in a radial direction of the motor.
3. The motor according to claim 1 , further comprising auxiliary magnets respectively attached to an upper surface and a lower surface of the rotor.
4. The motor according to claim 1 , wherein
each of the plurality of first rotor claw-shaped magnetic poles includes an extending portion extending in a radial direction of the motor, and a claw extending in the axial direction from a radial outer end of the extending portion,
each of the second rotor claw-shaped magnetic poles includes an extending portion extending in the radial direction, and a claw extending in the axial direction from a radial outer end of the extending portion,
the field magnet is placed between the extending portion of the first claw-shaped magnetic pole and the extending portion of the second claw-shaped magnetic pole,
a first axial end surface of the field magnet is exposed from a gap between the mutually adjacent extending portions of the first rotor claw-shaped magnetic poles, and a second axial end surface of the field magnet is exposed from a gap between the mutually adjacent extending portions of the second rotor claw-shaped magnetic poles.
5. The motor according to claim 1 , wherein
the rotor is one of a plurality of single rotors stacked along the axial direction,
the first rotor core includes a first core base and the plurality of first rotor claw-shaped magnetic poles, the plurality of first rotor claw-shaped magnetic poles are configured separately from the first core base, and are fixed to the first core base,
the second rotor core includes a second core base and the plurality of second rotor claw-shaped magnetic poles, the plurality of second rotor claw-shaped magnetic poles are configured separately from the second core base, and are fixed to the second core base,
at least the first rotor claw-shaped magnetic poles of the single rotors which are adjacent to each other in the axial direction are integrally connected to each other, and at least the second rotor claw-shaped magnetic poles of the single rotors which are adjacent to each other in the axial direction are integrally connected to each other.
6. The motor according to claim 1 , wherein
the stator includes a core back portion which connects the first stator core and the second stator core to each other and which configures an outer periphery of the stator,
the stator core comprises an integrally formed punched material including the first stator core, the plurality of first stator claw-shaped magnetic poles, the second stator core, the plurality of second stator magnetic poles and the core back portion, and
the stator core is formed by forming the punched material into an annular shape and by connecting both ends of the punched material to each other.
7. The motor according to claim 1 , further comprising a cylindrical housing, which accommodates the first and second stator cores, wherein
a housing-side positioning portion is arranged on an inner peripheral surface of the housing,
the first stator core and the second stator core respectively include outer peripheral portions, the outer peripheral portions connect the first stator core and the second stator core to each other, which are opposed in the axial direction,
the plurality of first stator claw-shaped magnetic poles and the plurality of second stator claw-shaped magnetic poles are respectively arranged on an inner peripheral portion of the first stator core and an inner peripheral portion of the second stator core, and
stator-side positioning portions which engage with the housing-side positioning portion in the circumferential direction are respectively formed on an outer peripheral portion of the first stator core and an outer peripheral portion of the second stator core.
8. The motor according to claim 1 , wherein
cut out portions are respectively formed in the first stator core and the second stator core, a winding lead-out hole is configured by bringing circumferential positions of the cut out portions into line with each other, and
an end of the coil portion is pulled out from the winding lead-out hole.