Multi-section permanent magnet rotor

Claim 2

A rotor for a permanent magnet machine comprising: a north and a south arcuate shaped pole piece; a shaft of magnetic material having a central portion with a substantially rhombic cross section, said north pole piece positioned adjacent one corner of said substantially rhombic central portion of said shaft and said south pole positioned adjacent a diagonally opposite corner of said shaft central portion, the major sides of said shaft central portion and the inner faces of said pole piece, defining the thickness in the radial direction of four apertures extending the axial length of the pole pieces; four magnets, each magnet positioned in one of said apertures, respectively, two of said magnets each having its north seeking face adjacent the north pole piece and two of said magnets each having its south seeking face adjacent the south pole piece; two arcuate shaped clamp pieces, each of said clamp pieces located between the north and south pole pieces and positioned to form a cylinder with said pole pieces; and fastening means extending through said clamp pieces into holes formed in diagonally opposite corners of said central portion of the shaft, said clamp pieces having inclined surfaces engaging matching surfaces on said pole pieces to force said pole pieces toward said central portion of said shaft and thereby apply compressive force on said magnets when said fastening means are tightened.

Claim 3

The rotor of claim 1 further comprising nonmagnetic flared keys positioned in an aperture formed in each of said pole pieces, respectively, said keys secured to a diagonally opposite corner, respectively, of said central shaft.

Claim 4

The rotor of claim 1 wherein the inclined surfaces of each of said arcuate shaped clamp pieces form an acute angle with the quadrature flux axis extending in the direction of movement of said fastening means during tightening, said inclined surfaces contacting mating surfaces on said pole pieces thereby causing said pole pieces to be forced toward said shaft when said fastening means are tightened.

Claim 5

The rotor of claim 1 wherein said fastening means are nonmagnetic.

Claim 6

The rotor of claim 1 wherein each of said pole pieces comprises a stack of laminations, respectively, each of said laminations being perpendicular to the axial direction of said rotor.

Claim 7

The rotor of claim 1 wherein each of said keys is secured to said shaft by a weld.

Claim 8

A rotor for a permanent magnet machine comprising: a north and a south arcuate shaped pole piece, two nonmagnetic inserts, one of said inserts being secured centrally on the interior portion of said north pole piece and the other of said inserts being secured centrally on the interior portion of said south pole piece; two nonmagnetic segments, one of said segments secured between one end of said north pole piece and one end of said south pole piece, the other of said segments secured between the other end of said south pole piece and the other end of said north pole piece, the segments and pole pieces thereby forming a hollow cylinder; a shaft of magnetic material having a central portion of substantially rhombic cross section, said shaft positioned in said hollow cylinder, one pair of diagonally opposite corners of the shaft being positioned adjacent said two nonmagnetic inserts, respectively, the other pair of diagonally opposite corners of the shaft positioned adjacent said nonmagnetic segments, respectively, the major sides of said shaft and the inner faces of said pole pieces defining the thickness in the radial direction of four apertures extending the axial length of the pole pieces; four permanent magnets, each of said magnets positioned in one of said apertures, respectively, first and second ones of the magnets each having its north seeking face adjacent said north pole piece and the third and fourth ones of the magnets each having its south seeking face adjacent said south pole piece, the adjacent ends of said first and second magnets being separated from one another by one of said central nonmagnetic inserts, the adjacent ends of said third and fourth magnets being separated from one another by the other of said central nonmagnetic insert, the adjacent ends of said first and fourth magnets being separated from one another by one of said nonmagnetic segments, and the adjacent ends of said second and third magnets being separated from one another by the other of said nonmagnetic segments, respectively; and means securing said magnets in said apertures.

Claim 9

A rotor for a permanent magnet machine comprising: a north and a south arcuate shaped pole piece, two nonmagnetic inserts, one of said inserts being secured centrally on the interior portion of said north pole piece and the other of said inserts being secured centrally on the interior portion of said south pole piece; two nonmagnetic segments, one of said segments secured between one end of said north pole piece and one end of said south pole piece, the other of said segments secured between the other end of said south pole piece and the other end of said north pole piece, the segments and pole pieces thereby forming a hollow cylinder; a shaft of magnetic material having a central portion of substantially rhombic cross section, said shaft positioned in said hollow cylinder, one pair of diagonally opposite corners of the shaft being positioned adjacent said two nonmagnetic inserts, respectively, the other pair of diagonally opposite corners of the shaft positioned adjacent said nonmagnetic segments, respectively, the major sides of said shaft and the inner faces of said pole pieces defining the thickness in the radial direction of four apertures extending the axial length of the pole pieces; four permanent magnets, each of said magnets positioned in one of said apertures, respectively, first and second ones of the magnets each having its north seeking face adjacent said north pole piece and the third and fourth ones of the magnets each having its south seeking face adjacent said south pole piece, the adjacent ends of said first and second magnets being separated from one another by one of said central nonmagnetic inserts, the adjacent ends of said third and fourth magnets being separated from one another by the other of said central nonmagnetic insert, the adjacent ends of said first and fourth magnets being separated from one another by one of said nonmagnetic segments, and the adjacent ends of said second and third magnets being separated from one another by the other of said nonmagnetic segments, respectively; and means securing said magnets in said apertures.

Claim 10

The rotor of claim 7 wherein said shaft is interference fit in said hollow cylinder.

Claim 11

The rotor of claim 7 wherein said north and south pole pieces each comprises two sections separated by and secured to one of said nonmagnetic inserts, respectively.

Claim 12

The rotor of claim 7 further comprising: means securing said nonmagnetic inserts to said shaft.

Claim 13

The rotor of claim 7 including bolt means extending through a hole in each of said nonmagnetic insert respectively into a separate threaded hole, respectively, formed in said shaft.

Claim 14

The rotor of claim 11 further comprising: means securing said nonmagnetic segments to said shaft.

Claim 15

The rotor of claim 12 including bolt means extending through a hole in each of said nonmagnetic segments, respectively, into a separate, additional threaded hole, respectively, formed in said shaft.

Claim 16

The rotor of claim 9 wherein each of said pole piece sections comprises a stack of laminations, the plane of said laminations being perpendicular to the axial direction of said rotor.

Claim 17

The rotor of claim 14 wherein said central nonmagnetic inserts and said nonmagnetic segments are secured to said laminated pole pieces by electron beam welds.

Claim 18

The rotor of claim 7 wherein said means securing said magnets in said apertures comprises an end ring positioned on either end, respectively, of said stack of laminations and secured to a nonmagnetic portion of said rotor.

Claim 19

The rotor of claim 11 wherein said bolt means is nonmagnetic.

Claim 20

The rotor of claim 13 wherein said bolt means is nonmagnetic.