Induction motor rotor and a method of manufacturing the same

Patent metadata

Field	Value
Publication number	US-10951101-B2
Application number	US-201615357647-A
Country	US
Kind code	B2
Filing date	Nov 21, 2016
Priority date	Dec 8, 2015
Publication date	Mar 16, 2021
Grant date	Mar 16, 2021

Abstract

A method of manufacturing an induction motor rotor assembly, the method includes the steps of: providing a rotor; machining a plurality of re-entrant slots axially along an outer surface of the rotor; positioning a sleeve concentrically over the outer surface of the rotor; applying a friction stir welding process to the sleeve along each re-entrant slot axially along the outer surface of the rotor to cause the sleeve material to plasticise and flow into the axial re-entrant slot to form an axial re-entrant slot bar; and providing an electrical connection at each of the opposing axial ends of the rotor between respective ones of opposing ends of each of the axial re-entrant slot bars to thereby form the induction motor rotor.

First claim

What is claimed is:

1. A method of manufacturing an induction motor rotor assembly, the method comprising the steps of:
providing a rotor that includes a first axial end, a second axial end, and an outer peripheral surface that extends between the first axial end and the second axial end;
machining a plurality of re-entrant slots axially along the outer peripheral surface of the rotor such that the re-entrant slots open at the outer peripheral surface and extend radially inward from the outer peripheral surface;
positioning a sleeve concentrically over the outer peripheral surface of the rotor, the sleeve being located radially outward of the outer peripheral surface of the rotor;
applying a friction stir welding process to the sleeve along each re-entrant slot axially along the outer peripheral surface of the rotor to cause the sleeve material to plasticise and flow radially inwardly into the axial re-entrant slot to form an axial re-entrant slot bar; and
providing an electrical connection at each of the first and second axial ends of the rotor between respective ones of opposing ends of each of the axial re-entrant slot bars to thereby form the induction motor rotor assembly.

2. The method as claimed in claim 1 , wherein the step of providing an electrical connection at each of the opposing axial ends of the rotor between respective ones of opposing ends of each of the axial re-entrant slot bars to thereby form the induction motor rotor assembly, comprises the step of:
attaching an end ring to each of the opposing axial ends of the rotor to connect together respective ones of opposing ends of each of the axial re-entrant slot bars to thereby form the induction motor rotor assembly.

3. The method as claimed in claim 1 , wherein the step of providing an electrical connection at each of the opposing axial ends of the rotor between respective ones of opposing ends of each of the axial re-entrant slot bars to thereby form the induction motor rotor assembly, comprises the steps of:
machining a re-entrant slot circumferentially around the outer peripheral surface of the rotor at each axial end of the rotor; and
applying a friction stir welding process to the sleeve along each re-entrant slot circumferentially around the outer peripheral surface of the rotor to cause the sleeve material to plasticise and flow into the circumferential re-entrant slot to form a circumferential re-entrant slot bar, to connect together respective ones of opposing ends of each of the axial re-entrant slot bars to thereby form the induction motor rotor assembly.

4. The method as claimed in claim 1 , further comprising the additional step of:
machining an outer surface of the sleeve to produce a machined surface.

5. The method as claimed in claim 1 , wherein each of the re-entrant slots has a cross-sectional profile selected from the group comprising dovetails, ellipses, circles, teardrops and other re-entrant geometries.

6. The method as claimed in claim 5 , wherein each of the re-entrant slots is a dovetail slot.

7. The method as claimed in claim 6 , wherein each side of a base of each dovetail slot is provided with a base radius.

8. The method as claimed in claim 6 , wherein an upper corner of each dovetail slot is provided with an upper corner radius.

9. An induction motor rotor assembly comprising:
a rotor, comprising a first axial end, an opposite second axial end, and an outer peripheral surface that extends between the first axial end and the second axial end;
a sleeve; and
first and second electrical connection portions,
the rotor further comprising a plurality of axial, re-entrant slots machined axially along the outer peripheral surface of the rotor such that the re-entrant slots open at the outer peripheral surface and extend radially inward from the outer peripheral surface, the sleeve extending circumferentially around the outer peripheral surface of the rotor, the sleeve being located radially outward of the outer peripheral surface of the rotor, the sleeve comprising a plurality of axial re-entrant slot bars extending radially inwardly from the sleeve, each re-entrant bar having a first end and an opposite second end, each axial re-entrant slot bar being accommodated in a respective one of the axial re-entrant slots, and each re-entrant slot bar being formed by material of the sleeve that has been filled into a respective one of the re-entrant slots,
the first electrical connection portion being attached to the first axial end of the rotor and connecting together the first ends of each of the axial re-entrant slot bars,
the second electrical connection portion being attached to the second axial end of the rotor and connecting together the second ends of each of the axial re-entrant slot bars.

10. The induction motor rotor assembly as claimed in claim 9 , wherein each of the first electrical connection portion and the second electrical connection portion is formed as an end ring attached to each of the first and second ends of the rotor respectively, each respective end ring connecting corresponding first ends and second ends of the axial re-entrant bars.

11. The induction motor rotor assembly as claimed in claim 9 , further comprising a re-entrant slot machined circumferentially around the outer peripheral surface of the rotor at each of the first end and the second end of the rotor, and additional circumferential re-entrant slot bars being accommodated in each of the circumferential slots, each of the additional circumferential re-entrant slot bars connecting together corresponding first ends and second ends of the axial re-entrant slot bars.

12. The induction motor rotor assembly as claimed in claim 9 , wherein each of the re-entrant slots has a cross-sectional profile selected from the group comprising dovetails, ellipses, circles, teardrops and other re-entrant shapes.

13. The induction motor rotor assembly as claimed in claim 9 , wherein each of the re-entrant slots is a dovetail slot.

14. The induction motor rotor assembly as claimed in claim 13 , wherein each side of a base of each dovetail slot is provided with a base radius.

15. The induction motor rotor assembly as claimed in claim 13 , wherein an upper corner of each dovetail slot is provided with an upper corner radius.

16. An induction motor comprising an induction motor rotot assembly as claimed in claim 9 .

17. The induction motor rotor assembly as claimed in claim 9 , wherein the axial re-entrant slots extend axially along the outer peripheral surface of the rotor at a skew angle to an axis of rotation of the rotor.

18. The induction motor rotor assembly as claimed in claim 17 , wherein the skew angle is in the range of 0° to 10° relative to the axis of rotation of the rotor.

19. The method as claimed in claim 1 , wherein the axial re-entrant slots extend axially along the outer peripheral surface of the rotor at a skew angle to an axis of rotation of the rotor.

20. The method as claimed in claim 19 , wherein the skew angle is in the range of 0° to 10° relative to the axis of rotation of the rotor.

Assignees

• Rolls Royce Plc

Inventors

• EMBERTON James
• Lambourne Alexis
• Cullen John J A

Classifications

• H02K15/021

  Magnetic cores · CPC title

• H02K15/023 Primary

  Cage rotors · CPC title

• H02K17/168

  having single-cage rotors · CPC title

• B23K20/122

  using a non-consumable tool, e.g. friction stir welding · CPC title

• H02K1/265

  Shape, form or location of the slots · CPC title