Magnetic geared rotating machine and power generation system
A magnetic geared rotating machine, includes: a stator which includes a plurality of stator magnets arranged so as to be aligned in a circumferential direction; a rotor which includes a plurality of rotor magnets arranged so as to be aligned in the circumferential direction, and in which the number of magnetic poles of the plurality of rotor magnets is less than the number of magnetic poles of the plurality of stator magnets; and a magnetic pole piece rotor which includes a plurality of magnetic pole pieces arranged so as to be aligned in the circumferential direction. Each of the magnetic pole pieces has: a first face opposed to the rotor in a radial direction; and a second face opposed to the stator in the radial direction and having a circumferential length longer than a circumferential length of the first face.
1. A magnetic geared rotating machine, comprising:
a stator which includes a plurality of stator magnets arranged so as to be aligned in a circumferential direction;
a rotor which includes a plurality of rotor magnets arranged so as to be aligned in the circumferential direction, and in which a number of magnetic poles of the plurality of rotor magnets is less than the number of magnetic poles of the plurality of stator magnets; and
a magnetic pole piece rotor which includes a plurality of magnetic pole pieces arranged so as to be aligned in the circumferential direction, wherein
each of the magnetic pole pieces has:
a first face opposed to the rotor in a radial direction; and
a second face opposed to the stator in the radial direction and having a circumferential length longer than a circumferential length of the first face,
the magnetic pole piece rotor includes a plurality of non-magnetic holders arranged in the circumferential direction alternately with the plurality of magnetic pole pieces,
each of the non-magnetic holders includes a holder surface extending in a direction approaching a circumferential midpoint of the non-magnetic holder as the holder surface goes inward in the radial direction,
each of the magnetic pole pieces has:
a third face opposed to and in contact with the holder surface; and
a fourth face located opposite to the third face in the circumferential direction,
a length in the circumferential direction from the third face to the fourth face is longer than the circumferential length of the second face,
θ A ≤0.67θ B , where
θ A is an angle defined as a value obtained by dividing an area of a region surrounded by an outer contour of the magnetic pole pieces in a radial cross section of the magnetic pole pieces by a length of the magnetic pole pieces in the radial direction and a length from a rotation center to a midpoint of the magnetic pole pieces in the radial direction, and
θ B is an angle defined, in regard to each of the two magnetic pole pieces adjacent in the circumferential direction, as a positive difference value of an angular position of each of the two magnetic pole pieces with respect to the rotation center.
2. The magnetic geared rotating machine according to claim 1 , wherein θ A ≥0.54θ B .
3. The magnetic geared rotating machine according to claim 1 , wherein 0.25L2<L1<0.75L2, where
L1 is the circumferential length of the first face, and
L2 is the circumferential length of the second face.
4. The magnetic geared rotating machine according to claim 1 , wherein
the magnetic pole piece rotor includes a connecting bar extending in an axial direction inside an axial hole disposed so as to penetrate the magnetic pole pieces in the axial direction, and
a radial position of a center of the axial hole is closer to the second face than a midpoint of the magnetic pole pieces in the radial direction.
5. The magnetic geared rotating machine according to claim 4 , wherein
the magnetic pole piece rotor includes a plurality of non-magnetic holders for sandwiching each of the plurality of magnetic pole pieces therebetween in the circumferential direction,
each of the non-magnetic holders includes a holder surface extending in a direction approaching a circumferential midpoint of the non-magnetic holder as the holder surface goes inward in the radial direction,
each of the magnetic pole pieces has:
a third face opposed to and in contact with the holder surface; and
a fourth face located opposite to the third face in the circumferential direction,
a length in the circumferential direction from the third face to the fourth face is longer than the circumferential length of the second face, and
a radial length from an inner side face of the first face or the second face located on an inner side in the radial direction to the center of the axial hole is longer than a maximum radial length from an outer side face located opposite to the inner side face to the third face.
6. The magnetic geared rotating machine according to claim 1 , wherein
the first face is exposed to a side of the rotor, and
the second face is exposed to a side of the stator.
7. A power generation system, comprising:
a prime mover; and
the magnetic geared rotating machine according to claim 1 , which serves as a magnetic geared generator driven by an input from the prime mover to generate power.