Magnet retention channel arrangement for high speed operation

• US 6,492,754 B1
• Filed: 10/31/2001
• Issued: 12/10/2002
• Est. Priority Date: 10/31/2001
• Status: Active Grant

• Current Assignee: Electric Boat Corporation (General Dynamics Corporation)
• Original Assignee: Electric Boat Corporation (General Dynamics Corporation)
• Inventors: Weiglhofer, John, Peil, Stewart
• Primary Examiner(s): Ramirez, Nestor
• Assistant Examiner(s): NGUYEN, HANH N
• Application Number:
  US09/998,973
• Time in Patent Office: 405 Days
• Field of Search: 310/156-1-1, 310/261, 310/262
• US Class Current: 310/156.08
• CPC Class Codes: H02K 1/2773 consisting of tangentially magnetized radial magnets

Abstract

In the magnet retention channel arrangement for a high speed rotor described in the specification, a rotor has an array of radially projecting, angularly spaced pole pieces and a magnet retention channel arrangement inserted between each adjacent pair of pole pieces. Each magnet retention channel arrangement has ferromagnetic side walls and a nonmagnetic alloy cap and nonmagnetic alloy dovetail feet affixed to opposite edges of the ferromagnetic side walls by welding or by a hot isostatic pressed powder metallurgy technique. The channels contain permanent magnets and the ferromagnetic side walls couple the flux from the magnets to the pole pieces with substantially no magnetic discontinuities and the nonmagnetic alloy cap and nonmagnetic core avoids magnetic shorting.

Claims

1. A magnet retention channel arrangement comprising:

a pair of spaced, parallel ferromagnetic side walls;

a nonmagnetic alloy cap bonded to a first edge of each of the ferromagnetic side walls; and

a pair of nonmagnetic alloy feet each bonded to a second, opposed edge of the two ferromagnetic side walls, respectively.

2. A magnet retention channel arrangement according to claim 1 wherein the nonmagnetic alloy cap and the nonmagnetic alloy feet are bonded to the ferromagnetic side walls by a hot isostatic pressed powder metallurgy technique.

3. A magnet retention channel arrangement according to claim 1 wherein the nonmagnetic alloy cap and the nonmagnetic alloy feet are bonded to the ferromagnetic side walls by welding.

4. A magnet retention channel arrangement according to claim 3 wherein the nonmagnetic alloy cap and the nonmagnetic alloy feet are bonded to the edges of the ferromagnetic side walls by electron beam welding.

5. A magnet retention channel arrangement according to claim 1 including at least one permanent magnet contained in the space between the ferromagnetic side walls.

6. A high speed rotor comprising:

a central shaft;

a nonmagnetic core;

a plurality of radially projecting, angularly spaced pole pieces made of ferromagnetic material and supported from the core; and

a plurality of magnet retention channel arrangements;

each channel arrangement being mounted between an adjacent pair of pole pieces and including;

a pair of spaced ferromagnetic side walls adjacent to the pole pieces;

a nonmagnetic alloy cap bonded to radially outer edges of the ferromagnetic side walls and a pair of nonmagnetic alloy feet bonded to radially inner edges of the ferromagnetic side walls and supported from the nonmagnetic core; and

at least one permanent magnet disposed in the space between the ferromagnetic side walls so that the ferromagnetic side walls provide flux paths between the magnet and the adjacent pole pieces having substantially no magnetic discontinuities and the nonmagnetic alloy cap inhibits magnetic shorting.

7. A high speed rotor arrangement according to claim 6 wherein the nonmagnetic alloy feet have dovetail projections received in corresponding recesses in a nonmagnetic core member affixed to the rotor shaft at a location outside the path of magnetic flux from the permanent magnet to the adjacent pole pieces.

8. A high speed rotor arrangement according to claim 7 wherein the ferromagnetic side walls are bonded to the nonmagnetic alloy cap and to the nonmagnetic alloy feet by a hot isostatic pressed powder metallurgy technique.

9. A high speed rotor arrangement according to claim 7 wherein ferromagnetic side walls are bonded to the nonmagnetic alloy cap and to the nonmagnetic alloy feet by welding.

10. A high speed rotor arrangement according to claim 9 wherein the ferromagnetic side walls are bonded to the nonmagnetic alloy cap and to the nonmagnetic alloy feet by electron beam welding.

11. A high speed rotor arrangement according to claim 6 wherein the ferromagnetic side walls of the channel arrangement have magnetic characteristics compatible to those of the adjacent pole pieces.