Permanent magnet motor

Claim 2

A subfractional reversible synchronous electrical motor comprising: a pair of annular inner stator members mounted together in coaxiaL back-to-back relation, each having n pole pieces equally spaced around the inside of the annulus and projecting outwardly parallel to the axis thereof, with the pole pieces of one inner stator member angularly displaced from the pole pieces of the other by an angle a of approximately 90*/n; a pair of annular electrical coils, each mounted in encompassing relation to the pole pieces of a respective one of said inner stator members; a pair of annular outer stator members of generally U-shaped cross-sectional configuration, mounted in coaxial relation on said inner stator members to enclose said coils, each outer stator member having n pole pieces projecting inwardly parallel to said axis and interleaved one-for-one in an annular array with the pole pieces of a respective one of said inner stator members; the pole pieces on each stator member being tapered in thickness to afford edge portions, facing the pole pieces of the other stator member interleaved therewith, that are substantially smaller in thickness than the base portions of said pole pieces; a shaft, extending coaxially through said stator members; and an annular permanent magnet rotor mounted on said shaft and extending through both sets of pole pieces, in coaxial relation, and having 2n equiangularly spaced magnetic poles.

Claim 3

A subfractional synchronous electrical motor according to claim 1 in which each of said inner stator members includes a number of index protrusions and an equal number of complementary index apertures, the index protrusions of each inner stator member fitting into the index apertures of the other, and in which all of the stator members are mounted together solely by being resin bonded to each other, to afford and maintain accurate angular alignment between the stator members.

Claim 4

A subfractional synchronous electrical motor according to claim 1 in which the taper of each pole piece is in the direction from base to free tip and is of the order of 3:1.

Claim 5

A subfractional synchronous electrical motor according to claim 1 in which the taper of each pole piece is from the central portion to the side edges, and is of the order of 3:1.

Claim 6

A subfractional reversible synchronous electrical motor according to claim 1 in which the width/thickness ratio of each pole piece is at least 2.5.

Claim 7

A subfractional reversible synchronous electrical motor comprising: a pair of annular inner stator members mounted together in coaxial back-to-back relation, each having n pole pieces equally spaced around the inside of the annulus and projecting outwardly parallel to the axis thereof, with the pole pieces of one inner stator member angularly displaced from the pole pieces of the other by an angle a of approximately 90*/n; a pair of annular electrical coils, each mounted in encompassing relation to the pole pieces of a respective one of said inner stator members; a pair of annular outer stator members of generally U-shaped cross-sectional configuration, mounted on said inner stator members in coaxial relation and enclosing said coils, each outer stator member having n pole pieces projecting inwardly parallel to said axis and interleaved one-for-one in an annular array with the pole pieces of a respective one of said inner stator members; the pole pieces on each stator member being tapered in thickness to afford edge portions, facing the pole pieces of the other stator member interleaved therewith, that are substantially smaller in thickness than the base portions of said pole pieces; each of said stator members being formed of mild low-carbon steel annealed after fabrication to obtain maximum flux capacity; a shaft, extending coaxially through said stator members; and an annular permanent magnet rotor mounted on said shaft and extending through both sets of pole pieces, in coaxial relation, and having 2n equiangularly spAced magnetic poles.

Claim 8

A subfractional reversible synchronous electrical motor comprising: a pair of annular inner stator members mounted together in coaxial back-to-back relation, each having n pole pieces equally spaced around the inside of the annulus and projecting outwardly parallel to the axis thereof, with the pole pieces of one inner stator member angularly displaced from the pole pieces of the other by an angle a of approximately 90*/n; a pair of annular electrical coils, each mounted in encompassing relation to the pole pieces of a respective one of said inner stator members; a pair of annular outer stator members of generally U-shaped cross-sectional configuration, mounted on said inner stator members in coaxial relation and enclosing said coils, each outer stator member having n pole pieces projecting inwardly parallel to said axis and interleaved one-for-one in an annular array with the pole pieces of a respective one of said inner stator members; the pole pieces on each stator member being tapered in thickness to afford edge portions, facing the pole pieces of the other stator member interleaved therewith, that are substantially smaller in thickness than the base portions of said pole pieces; each of said stator members being formed of mild low-carbon steel annealed after fabrication to obtain maximum flux capacity; a shaft, extending coaxially through said stator members; and an annular permanent magnet rotor mounted on said shaft and extending through both sets of pole pieces, in coaxial relation, and having 2n equiangularly spAced magnetic poles.

Claim 9

A subfractional reversible synchronous motor according to claim 6, in which the taper of each of said pole pieces is at least 3:1.

Claim 10

A subfractional reversible synchronous motor according to claim 6, in which the width/thickness ratio of each pole piece is at least 2.5.

Claim 11

A subfractional reversible synchronous motor according to claim 8, said motor further comprising: a bearing bracket affixed to one of said outer stator members; an elongated bearing sleeve mounted on said bearing bracket and extending coaxially of said stator members; said shaft being journaled in said bearing sleeve and having a nonmagnetic cantilever hub mounted thereon beyond the end of said sleeve, said magnet being mounted on said hub.

Claim 12

A subfractional synchronous electrical motor according to claim 11 in which each of said inner stator members includes a number of index protrusions and an equal number of complementary index apertures, the index protrusions of each inner stator member fitting into the index apertures of the other, and in which all of the stator members are mounted together solely by being resin bonded to each other, to afford and maintain accurate angular alignment between the stator members.