Permanent magnet machine rotor
A rotor for an interior permanent magnet machine has a rotor body having an output shaft and a first cavity filled with magnetic material. Second cavities are disposed inboard of the first cavities and are not filled with magnetic material. Non-magnetic rods extend through the second cavities and protrude beyond end faces of the rotor body. The rods are press-fit in blind bores formed in non-magnetic end plates disposed adjacent the end faces of the rotor body. Shrink disks are shrunk around projecting ends of the output shaft in abutting relation with the end plates. In order to prevent induced voltage from generating current in the cage formed by the rods and end plates, an oxide layer is disposed between the rods and blind bores in the end plates.
1. A rotor for an interior permanent magnet machine, comprising:
a cylindrical body comprising non-magnetic material having an axial shaft projecting therefrom, the cylindrical body having first and second ends and a cylindrical outer surface;
an array of first cavities therein containing permanent magnets and array of second cavities therein that do not contain magnets, the cavities being separated by rotor bridges comprising the non-magnetic material, wherein the array of first cavities are distributed adjacent to each other at a first radial distance from the axial shaft and the second set of cavities are located at a second radial distance from the axial shaft, and wherein the first radial distance is greater than the second radial distance;
an array of rods of non-magnetic material extending through the second cavities in the rotor, and first and second end plates disposed adjacent the first and second ends of the rotor and fixed to the array of rods;
wherein at least one of the end plates has an insulating oxide layer between the rods and end plate.
2. The rotor of claim 1 , wherein the rods and end plates are made of stainless steel or titanium.
3. The rotor of claim 2 , wherein the rods have end protrusions that are received in blind bores in the end plates and wherein the end plates are held adjacent to the ends of the rotor.
4. The rotor of claim 2 , wherein the rods have first and second end protrusions protruding beyond the first and second ends of the rotor and wherein the end plates have blind bores therein, in which blind bores the end protrusions of the rods are retained by press-fit.
5. The magnetic machine rotor of claim 4 , wherein shrink disks are shrunk over ends of the output shaft outboard of the end plates.
6. The magnetic machine rotor of claim 4 , wherein the first cavities are arranged in groups adjacent to the second cavities with a plurality of first cavities extending obliquely away from the second cavities toward the outer cylindrical surface of the rotor.
7. The magnetic machine rotor of claim 1 , wherein the first cavities are arranged in groups adjacent to the second cavities with a plurality of first cavities extending obliquely away from the second cavities toward the outer cylindrical surface of the rotor.