Rotor for an electric machine

• US 10,587,169 B2
• Filed: 05/25/2017
• Issued: 03/10/2020
• Est. Priority Date: 05/25/2016
• Status: Active Grant

• Current Assignee: Volkswagen AG
• Original Assignee: Volkswagen AG
• Inventors: Gruetzner, Stefan, Riehm, Christian
• Primary Examiner(s): Luks, Jeremy A
• Application Number:
  US15/604,909
• Publication Number:
  US 20170346371A1
• Time in Patent Office: 1,020 Days
• Field of Search: 310 61, 310 60 A, 310216011, 310216013, 310216014
• CPC Class Codes: H02K 1/32 with channels or ducts for flow of cooling medium
• CPC Class Codes: H02K 9/197 in which the rotor or stator space is fluid-tight, e.g. to provide for different cooling media for rotor and stator

Abstract

A rotor for an electric machine is formed of a rotor shaft and a rotor body which is non-rotatably mounted on the rotor shaft. At least sections of the rotor shaft are configured as a hollow shaft. A delivery screw is non-rotatably mounted in the hollow shaft for conveying a cooling fluid in a first direction through the hollow shaft. In order to provide an improved cooling of the rotor, the rotor body is formed with at least one cooling channel which extends in the axial direction. The cooling channel has an end-face inlet opening and an end-face outlet opening positioned on the opposite side for the cooling fluid. The cooling fluid conveyed in the first direction through the hollow shaft can be at least partially directed through the inlet opening into the cooling channel and conveyed in a second direction, which is counter to the first direction, to the outlet opening.

Claims

1. A rotor for an electric machine, the rotor comprising:

a rotor shaft and a rotor body non-rotatably mounted to said rotor shaft, said rotor shaft being a hollow shaft at least in sections thereof;

a delivery screw non-rotatably mounted in said hollow shaft and configured to convey a cooling fluid through said hollow shaft in a first direction being an axial direction extending along an axis of said hollow shaft;

said rotor body being formed with at least one cooling channel for the cooling fluid, said at least one cooling channel extending in an axial direction and including an end-face inlet opening and an end-face outlet opening on mutually opposite sides, wherein the cooling fluid conveyed in the first direction through said hollow shaft is at least partially directed through said inlet opening into said cooling channel and then conveyed in a second direction, counter to the first direction, to said outlet opening; and

wherein said hollow shaft and said at least one cooling channel are fluidically connected, via said end-face inlet opening and said end-face outlet opening, to form an autonomously operating closed cooling circuit within the rotor.

2. The rotor according to claim 1, wherein said hollow shaft delimits an inner chamber and wherein at least one of said inlet opening and said outlet opening of said cooling channel in said rotor body is formed to fluidically communicate with said inner chamber.

3. The rotor according to claim 1, wherein said hollow shaft is formed with at least one first radial opening for an emergence of the cooling fluid, after having been conveyed through said hollow shaft, out of said hollow shaft, and wherein a guide element for guiding the cooling fluid is disposed between said first radial opening in said hollow shaft and said inlet opening of said cooling channel.

4. The rotor according to claim 3, wherein said hollow shaft is formed with at least one second radial opening for an entry of the cooling fluid, after having been conveyed through said cooling channel of said rotor body, into said hollow shaft, and wherein a guide element for guiding the cooling fluid is disposed between said outlet opening of said cooling channel and said second radial opening in said hollow shaft.

5. The rotor according to claim 4, wherein said at least one first radial opening is one of a plurality of first radial openings and/or said at least one second radial opening is one of a plurality of second radial openings evenly distributed in the circumferential direction in said hollow shaft.

6. The rotor according to claim 1, wherein said delivery screw is a right-hand or left-hand single-start or multiple-start helix.

7. The rotor according to claim 6, wherein said at least one cooling channel in said rotor body is a helix that extends in an opposite direction of the helix of said delivery screw.

8. The rotor according to claim 1, wherein said rotor body is a rotor laminated core consisting of a plurality of rotor laminations, and wherein said at least one cooling channel is formed by recesses in said rotor laminations.

9. The rotor according to claim 8, wherein said recesses in adjacent rotor laminations have an offset in a circumferential direction between 3°

and 7°

, and wherein said recesses in the rotor laminations, in combination, form a helical cooling channel.

10. The rotor according to claim 1, wherein said rotor body is formed with a plurality of axially extending cooling channels that are evenly distributed in a circumferential direction.

11. The rotor according to claim 1, wherein said hollow shaft is formed with a plurality of first radial openings and/or a plurality of second radial openings that are evenly distributed in a circumferential direction in said hollow shaft.