Sleeve for an electrical machine

Patent metadata

Field	Value
Publication number	US-10122228-B2
Application number	US-201615047094-A
Country	US
Kind code	B2
Filing date	Feb 18, 2016
Priority date	Mar 13, 2015
Publication date	Nov 6, 2018
Grant date	Nov 6, 2018

Abstract

A sleeve for retaining magnets around a rotor of an electrical machine. The sleeve is cylindrical and hollow, having axial length and having radial thickness between its inner surface and outer surface. The sleeve defines a plurality of axially spaced, circumferentially extending grooves. Each groove has radial depth which is less than the radial thickness of the sleeve.

First claim

The invention claimed is:

1. A sleeve for retaining magnets around a rotor of an electrical machine, the sleeve comprising:
a body that is cylindrical and hollow, the body having an inner surface and an outer surface, the body having an axial length and a radial thickness between the inner surface and the outer surface; and
a first plurality of axially spaced, circumferentially extending grooves formed in the inner surface of the body, each groove of the first plurality of grooves having a radial depth less than the radial thickness of the sleeve and extending circumferentially through less than 360°.

2. The sleeve as claimed in claim 1 , wherein a radial bridge is a difference between the radial thickness of the sleeve and the radial depth of each groove of the first plurality of grooves, the radial bridge being greater than or equal to ⅓ of an electrical skin depth of the sleeve.

3. The sleeve as claimed in claim 2 , wherein the radial depth of each radial bridge of each groove of the first plurality of grooves is equal to ⅓ of the radial thickness of the sleeve where the electrical skin depth is greater than the radial thickness of the sleeve.

4. The sleeve as claimed in claim 1 , wherein the grooves of the first plurality of grooves have the same radial depth.

5. The sleeve as claimed in claim 1 , wherein each groove of the first plurality of grooves extends circumferentially through at least 60°.

6. The sleeve as claimed in claim 1 , wherein a circumferential bridge is defined between circumferential ends of one or two circumferentially aligned grooves of the first plurality of grooves, and axially adjacent circumferential bridges are circumferentially offset.

7. The sleeve as claimed in claim 6 , wherein two or more circumferential bridges are axially aligned and circumferentially spaced.

8. The sleeve as claimed in claim 7 , wherein the axially aligned grooves of the first plurality of grooves have equal circumferential extent.

9. The sleeve as claimed in claim 1 , further comprising a second plurality of grooves extending around the outer surface of the sleeve.

10. The sleeve as claimed in claim 9 , wherein at least one groove of the first plurality of grooves is radially aligned with at least one groove of the second plurality of grooves.

11. The sleeve as claimed in claim 9 , wherein a combined radial depth including the radial depth of the first plurality of grooves and a radial depth of the second plurality of grooves is less than the radial thickness of the sleeve.

12. The sleeve as claimed in claim 1 , wherein the sleeve is metal.

13. An electrical machine rotor comprising:
a rotor shaft;
a plurality of permanent magnets located in a circumferential array around a surface of the rotor shaft; and
the sleeve as claimed in claim 1 , the sleeve being affixed radially outside the plurality of permanent magnets to retain them to the rotor shaft.

14. An electrical machine rotor comprising:
a rotor shaft;
at least one electrical coil located on a surface of the rotor shaft; and
the sleeve as claimed in claim 1 , the sleeve being affixed radially outside the at least one electrical coil to retain the at least one electrical coil to the rotor shaft.

15. An electrical machine comprising the electrical machine rotor as claimed in claim 13 .

16. A method of fabricating the sleeve as claimed in claim 1 , the method comprising steps to:
form the cylindrical sleeve; and
cut the first plurality axially spaced, circumferentially extending grooves into the inner surface of the sleeve.

17. A method as claimed in claim 16 , wherein the step to cut the grooves is performed by water jet machining.

Assignees

• Rolls Royce Plc

Inventors

• Chong Ellis F H
• Jones Martyn A
• Jewell Geraint W

Classifications

• H02K1/28 Primary

  Means for mounting or fastening rotating magnetic parts on to, or to, the rotor structures · CPC title

• H02K1/274 Primary

  the rotor consisting of two or more circumferentially positioned magnets · CPC title

• Y02E10/725

  Cross-Sectional Technologies · mapped topic

• H02K15/14

  Casings; Enclosures; Supports · CPC title

• Y02E10/72

  Wind turbines with rotation axis in wind direction · CPC title