Method of manufacturing the rotor assembly for an electric motor

Patent metadata

Field	Value
Publication number	US-9899900-B2
Application number	US-201514598019-A
Country	US
Kind code	B2
Filing date	Jan 15, 2015
Priority date	Jan 15, 2015
Publication date	Feb 20, 2018
Grant date	Feb 20, 2018

Abstract

A method is provided for fabricating a rotor assembly for an electric motor which utilizes pre-fabricated conductive rotor bars and die cast end rings. Containment rings, which may be installed on the end rings either before or after casting, may be used to inhibit end ring creep at high rotational speeds.

First claim

What is claimed is:

1. A method of fabricating a rotor assembly for an electric motor, comprising:
assembling a lamination stack, wherein said lamination stack is comprised of a plurality of lamination discs, wherein each of said lamination discs is comprised of a first plurality of slots, and wherein each of said lamination discs is further comprised of a central bore;
inserting a plurality of pre-fabricated conductive rotor bars into said first plurality of slots corresponding to said lamination stack, wherein a first end portion of each of said plurality of pre-fabricated conductive rotor bars extends beyond a first end surface of said lamination stack, and wherein a second end portion of each of said plurality of pre-fabricated conductive rotor bars extends beyond a second end surface of said lamination stack;
locating a shaft within said central bore of said lamination stack;
locating a first member adjacent to said first end surface of said lamination stack, wherein at least a portion of said first member is encircled by said first end portion of each of said plurality of pre-fabricated conductive rotor bars, and wherein said first member at least partially defines a first end ring of said rotor assembly;
locating a second member adjacent to said second end surface of said lamination stack, wherein at least a portion of said second member is encircled by said second end portion of each of said plurality of pre-fabricated conductive rotor bars, and wherein said second member at least partially defines a second end ring of said rotor assembly;
die casting said first end ring and said second end ring of said rotor assembly, wherein said first end ring is comprised of said first end portion of each of said plurality of pre-fabricated conductive rotor bars, and wherein said second end ring is comprised of said second end portion of each of said plurality of pre-fabricated conductive rotor bars; and
removing said shaft, said first member and said second member from said rotor assembly.

2. The method of claim 1 , further comprising:
fitting a first containment ring around said first end portion of each of said plurality of pre-fabricated conductive rotor bars, wherein said step of fitting said first containment ring is performed prior to said step of die casting said first end ring and said second end ring of said rotor assembly; and
fitting a second containment ring around said second end portion of each of said plurality of pre-fabricated conductive rotor bars, wherein said step of fitting said second containment ring is performed prior to said step of die casting said first end ring and said second end ring of said rotor assembly.

3. The method of claim 2 , further comprising fabricating said first containment ring and said second containment ring from a material selected from the group consisting of a stainless steel, a beryllium copper alloy, and a metal matrix composite.

4. The method of claim 1 , further comprising:
machining said first end ring to remove a first circumferential portion corresponding to said first end ring, wherein said step of machining said first end ring is performed after completion of said die casting step;
fitting a first containment ring around said first end ring, wherein said first containment ring encircles said first end portion of each of said plurality of pre-fabricated conductive rotor bars, and wherein said first containment ring is positioned where said first circumferential portion of said first end ring was removed during said step of machining said first end ring;
machining said second end ring to remove a second circumferential portion corresponding to said second end ring, wherein said step of machining said second end ring is performed after completion of said die casting step; and
fitting a second containment ring around said second end ring, wherein said second containment ring encircles said second end portion of each of said plurality of pre-fabricated conductive rotor bars, and wherein said second containment ring is positioned where said second circumferential portion of said second end ring was removed during said step of machining said second end ring.

5. The method of claim 4 , further comprising fabricating said first containment ring and said second containment ring from a material selected from the group consisting of a stainless steel, a beryllium copper alloy, and a metal matrix composite.

6. The method of claim 4 , further comprising holding said first containment ring in place around said first end ring and holding said second containment ring in place around said second end ring utilizing one of the following steps:
a step of forming a first interference fit between said first containment ring and said first end ring and forming a second interference fit between said second containment ring and said second end ring;
a step of soldering said first containment ring to said first end ring and soldering said second containment ring to said second end ring;
a step of welding said first containment ring to said first end ring and welding said second containment ring to said second end ring; and
a step of bonding said first containment ring to said first end ring and bonding said second containment ring to said second end ring.

7. The method of claim 1 , further comprising fabricating said plurality of pre-fabricated conductive rotor bars from an oxygen-free electrolytic copper.

8. The method of claim 1 , further comprising:
fabricating said shaft, said first member and said second member from steel; and
coating said shaft, said first member and said second member with a non-stick coating to prevent adhesion between said steel and a casting material.

9. The method of claim 1 , further comprising fabricating said shaft and said first member as a single component.

10. The method of claim 1 , said step of assembling said lamination stack further comprising:
stamping each of said plurality of lamination discs from a metal; and
coating each of said plurality of lamination discs with an electrically insulating coating.

11. The method of claim 1 , said step of assembling said lamination stack further comprising:
fabricating each of said plurality of lamination discs from a metal;
fabricating a plurality of electrically insulating spacer discs; and
interposing one of said plurality of electrically insulating spacer discs between adjacent lamination discs of said plurality of lamination discs.

12. The method of claim 1 , said step of assembling said lamination stack further comprising:
locating a first end stack lamination disc at a first end of said lamination stack; and
locating a second end stack lamination disc at a second end of said lamination stack, wherein a first thickness corresponding to said first end stack lamination disc is thicker than a third thickness corresponding to each of said plurality of lamination discs interposed between said first end stack lamination disc and said second end stack lamination disc, and wherein a second thickness corresponding to said second end stack lamination disc is thicker than said third thickness corresponding to each of said plurality of lamination discs interposed between said first end stack lamination disc and said second end stack lamination disc.

13. The method of claim 12 , said first and second end stack lamination discs comprised of a second plurality of slots, wherein each of said second plurality of slots is of an approximately equivalent size to each of said first plurality of slots.

14. The method of claim 12 , said first and second end stack lamination discs comprised of a second plurality of slots, w

Assignees

• Atieva Inc

Inventors

• Mayer Jeremy
• Tang Yifan

Classifications

• H02K15/024 Primary

  Electricity · mapped topic

• H02K19/10

  for multi-phase current · CPC title

• Y10T29/49012

  Rotor · CPC title

• Y10T29/49009

  Dynamoelectric machine · CPC title

• H02K19/04

  for single-phase current · CPC title