SQUIRREL CAGE ROTOR FOR AN ASYNCHRONOUS MACHINE

Abstract

A squirrel cage rotor for an asynchronous machine includes a magnetically conductive main body which is mounted for rotation about an axis and includes electric conductors in substantially axially extending slots. The electric conductors are electrically contacted by short-circuit rings which are located on end faces of the magnetic main body and configured as a thermosiphon.

Claims

1.-8. (canceled)

9. A squirrel cage rotor of an asynchronous machine, said squirrel cage rotor mounted for rotation about an axis and comprising: a magnetically conductive main body; a shaft; short-circuit rings provided on end faces of the magnetic main body and thermally linked to the shaft, each said short-circuit ring having a void embodying a thermosiphon; and electrical conductors extending substantially axially in slots of the main body and electrically contacted by the short-circuit rings.

10. The squirrel cage rotor of claim 9, wherein at least one member selected from the group consisting of the short-circuit rings and the main body is connected to the shaft in a torsion-proof manner.

11. The squirrel cage rotor of claim 9, wherein the shaft includes a shaft cooling system.

12. The squirrel cage rotor of claim 9, wherein the short-circuit rings are configured hollow such as to realize evaporation or condensation of a cooling medium in the void of the short-circuit ring.

13. The squirrel cage rotor of claim 12, wherein the void of the short-circuit ring is bounded by a surface in facing relation to the end face of the magnetic main body and/or the shaft, said surface extending at a predetermined angle in relation to the axis or the end face.

14. An asynchronous machine, comprising a squirrel cage rotor as drive for a wheeled or track-based vehicle, for a maritime application, and as drive for aircraft, said squirrel cage rotor mounted for rotation about an axis and comprising a magnetically conductive main body, a shaft, short-circuit rings provided on end faces of the magnetic main body and thermally linked to the shaft, each said short-circuit ring having a void embodying a thermosiphon, and electrical conductors extending substantially axially in slots of the main body and electrically contacted by the short-circuit rings.

15. The asynchronous machine of claim 14, wherein at least one member selected from the group consisting of the short-circuit rings and the main body is connected to the shaft in a torsion-proof manner.

16. The asynchronous machine of claim 14, wherein the shaft includes a shaft cooling system.

17. The asynchronous machine of claim 14, wherein the short-circuit rings are configured hollow such as to realize evaporation or condensation of a cooling medium in the void of the short-circuit ring.

18. The asynchronous machine of claim 17, wherein the void of the short-circuit ring is bounded by a surface in facing relation to the end face of the magnetic main body and/or the shaft, said surface extending at a predetermined angle in relation to the axis or the end face.

19. A method for producing a squirrel cage rotor of an asynchronous machine, said method comprising: inserting electrical conductors into substantially axially extending slots of a magnetically conductive main body; producing short-circuit rings with a void using a 3D printing process, sand casting, or sealing a cast one of the short-circuit rings by a cover such that the void embodies a thermosiphon; and placing the short-circuit ring on end faces of the magnetically conductive main body such as to electrically contact the conductors.

20. The method of claim 19, further comprising setting in the void of the short-circuit ring an operating pressure for an operating temperature of the asynchronous machine to establish an ideal operating point of coolant in the void of the short-circuit ring.

21. The method of claim 19, wherein the operating pressure is a vacuum.

Description

[0020] The invention as well as further advantageous embodiments of the invention will be explained below in greater detail with reference to an exemplary embodiment shown as a basic diagram: In the figures

[0021] FIG. 1 shows a basic longitudinal section of an asynchronous motor,

[0022] FIG. 2 shows a detailed diagram in longitudinal section of a short-circuit ring.

[0023] FIG. 1 shows a basic longitudinal section of an asynchronous motor 1 with a stator 2 embodied from laminated sheets of metal, which has a winding system 3 in slots of the stator 2 not shown in any greater detail, which forms winding heads on the end faces of the stator 2. Via an air gap 4 of the asynchronous machine, by electromagnetic interaction with a squirrel cage rotor there is rotation about an axis 8. The squirrel cage rotor has a magnetically conductive main body 5, which in this case is embodied as an axially layered laminated core, but can also be provided as a one-piece sintered part.

[0024] Here electric conductors 7, which are electrically contacted with short-circuit rings 6 on the end faces of the magnetic main body 5, run in axial slots of the squirrel cage rotor not shown in any greater detail. In this form of embodiment the short-circuit rings 6 on the end faces are in thermal conductive contact both with the end face 21 of the magnetic main body 5 and also with a shaft 9.

[0025] Each short-circuit ring 6 has a void, which is embodied as a thermosiphon 11. According to the invention a condensation or a formation of vapor now takes place in this void such that the recooling again takes place in the area of the radial inner area of the thermosiphon 9, in other words in the area of the shaft 9. The shaft 9 itself is recooled in this case by lance cooling not shown in any greater detail by means of a hole 10 drilled in the shaft and a coolant 12, liquid or air, provided therein.

[0026] Thus the resistance effect losses of the squirrel cage rotor are, inter alia, now at least emitted in part via the thermosiphon 11 of the short-circuit ring 6, which is preferably in direct thermal contact with the end faces 21, to a liquid-cooled or air-cooled shaft 9 and its coolant 12. A further thermally conductive path is produced from the magnetically conductive main body 5 directly to the shaft 9.

[0027] FIG. 2 shows a detailed view of a short-circuit ring 6 with its thermosiphon 11, wherein an electric conductor 7 is electrically contacted with the short-circuit ring 6. The losses arising in the squirrel cage rotor, in particular in the short-circuit ring 6, are now emitted via a coolant 13 on its radial way outwards via the inclined surfaces 18 to the coolant 13, which on its radial way outwards more and more adopts a vaporized state 16. As a result of the overpressure forming in the radially outer area of the thermosiphon 11, the vapor is now pushed radially inwards towards the shaft 9. In this process a condensation occurs once again at the shaft 9, preferably on the surfaces 19 and the circuit can be executed once again. The short-circuit ring 6 is at least linked thermally directly to the shaft 9 by means of a transitional heat zone 20.

[0028] A cover 17 is provided primarily when the void of the short-circuit ring 6 is produced by a metal-cutting work process.

[0029] The respective vacuum openings not shown in any greater detail are preferably located on the short-circuit rings 6 in a direction parallel to the axis.

[0030] The surfaces 18, 19 are designed to be inclined in relation to the axis 8, in order to be able to provide the required surfaces for evaporation or recooling. Additional profilings of these surfaces 18, 19, for example by microscale structures in the mm range, can improve the desired effects even further.

[0031] In order to increase the desired cooling effect, ribs extending axially and radially, starting from the cover side 17 or from the inclined surface 18, are provided in the void of the short-circuit ring 6. Their geometrical extent in the axial and radial direction, depending on the embodiment of the short-circuit ring 6, stretches from a few mm up to the entire possible radial and axial extent within the void. Accordingly a storage structure is formed within the void, of which the segments between the ribs are connected with one another in terms of flow or are self-contained in each case.

[0032] With self-contained segments in terms of flow the respective operating pressure is then naturally to be set for each segment.

[0033] Thus the surfaces for evaporation and recooling are increased. Specific surfaces for evaporation and recooling within the void of the short-circuit ring 6 can also be produced by methods of additive manufacturing for a void in the short-circuit ring 6 generated by a metal cutting method.

[0034] Basically the entire short-circuit ring, even with these types of specific surfaces for evaporation and recooling in the void, can also be produced as follows. In such cases the inventive short-circuit ring with thermosiphon 11 is pressed onto a conventional laminated core of the short circuit rotor with conductor bars and a shaft 9, in particular a hollow shaft. In this case above all the thermal transitions short-circuit ring and end faces of the laminated core and also shaft 9 to short-circuit ring 6 are embodied with low thermal transfer resistances.