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DE-102024133064-A1 - Rotor shaft, rotor and separately excited synchronous machine with such a rotor

DE102024133064A1DE 102024133064 A1DE102024133064 A1DE 102024133064A1DE-102024133064-A1

Abstract

The present invention relates to a rotor shaft (1) for a separately excited synchronous machine (12), with a first, hollow shaft section (2) which is at least partially made of a first material with a magnetic permeability of µr ~ 1. This eliminates the need for previously often required shielding or a physical distance between the rotor and the transformer.

Inventors

  • Mario Mohler
  • Christoph Steinmetz
  • Leonard Lorenz
  • Hans Christian Uibeleisen

Assignees

  • MAHLE INTERNATIONAL GMBH

Dates

Publication Date
20260513
Application Date
20241112

Claims (13)

  1. Rotor shaft (1) for a separately excited synchronous machine (12), with a first, hollow shaft section (2) which is at least partially made of a first material with a magnetic permeability of µr ~ 1.
  2. Rotor shaft (1) after Claim 1 , characterized in that - a second shaft section (3) is provided connected to the first, hollow shaft section (2), - the second shaft section (3) consists of an alloyed or unalloyed steel as the second material, in particular with a magnetic permeability of µr >> 1.
  3. Rotor shaft (1) after Claim 1 or 2 , characterized in that the first material is an austenitic steel.
  4. Rotor shaft (1) after Claim 2 or 3 , characterized in that the second material has a strength of at least 500 N/mm 2 , in particular is a hardenable steel.
  5. Rotor shaft (1) according to one of the Claims 2 until 4 , characterized in that the first wave section (2) and the second wave section (3) are materially bonded to each other, in particular welded, glued or soldered together.
  6. Rotor shaft (1) according to one of the Claims 2 until 4 , characterized in that the first wave section (2) and the second wave section (3) are pressed together.
  7. Rotor shaft (1) according to one of the Claims 2 until 6 , characterized in that the second wave section (3) is hollow.
  8. Rotor shaft (1) according to one of the Claims 2 until 7 , characterized in that an output contour (9), in particular a splined connection, is arranged on the second shaft section (3).
  9. Rotor shaft (1) according to one of the Claims 2 until 8 , characterized in that the first wave section (2) and the second wave section (3) are connected to each other via a butt joint.
  10. Rotor shaft (1) according to one of the Claims 2 until 8 , characterized in that the first wave section (2) and the second wave section (3) are inserted into each other.
  11. Rotor (11) for a separately excited synchronous machine (12) with a rotor shaft (1) according to one of the preceding claims.
  12. Rotor (11) after Claim 11 , characterized in that a transformer (8), in particular a ferrite core or an electronic component, in particular a rectifier, is arranged in a cavity (6) of the first shaft section (2).
  13. separately excited synchronous machine (12) with a rotor (11) according Claim 11 or 12 .

Description

The present invention relates to a rotor shaft for a separately excited synchronous machine. The invention also relates to a rotor for a separately excited synchronous machine with such a rotor shaft, and to a separately excited synchronous machine with such a rotor. From the EP 1 309 066 A2 A stamped sheet metal component for the rotor of a synchronous machine is known, featuring a plurality of circumferentially arranged recesses into which two permanent magnets can be inserted, and in which an intermediate sheet segment is arranged between the permanent magnets. The recesses are shaped such that, when the permanent magnets are inserted radially outward within the respective recess, an air gap exists between the radially centered surface of the intermediate sheet segment and a radially outward-facing edge of the recess. This is intended to achieve the necessary damping of leakage flux. From the DE 10 2010 061 778 A1 A spoked rotor for an electric machine with a rotor shaft rotatable about a rotor axis is known. The spoked rotor also has a base body arranged concentrically around the rotor axis and a permanent magnet arranged in a spoke-like manner within a recess in the base body. The rotor shaft and/or a connecting sleeve located between the rotor shaft and the base body, which fixes the base body to the rotor shaft, are made of a diamagnetic material or a paramagnetic material with a permeability µr < 20. This is intended to create an electric machine in which stray losses are further reduced. There are separately excited synchronous machines with contactless current transmission to a rotor via a rotary transformer. In this design, part of the rotary transformer can be integrated into the rotor shaft. Such contactless synchronous machines offer the significant advantage of eliminating wear-prone sliding contacts. Conventional rotor shafts for such separately excited synchronous machines are often made of steel, which has a high magnetic permeability µr of approximately 40–950. This allows the magnetic field generated in the rotor to penetrate inwards and remain present within the rotor shaft. This has a particularly negative impact on the properties of the transformer/core integrated into the rotor shaft. The transformer core of a contactless transformer is preferably designed to conduct the transformer's magnetic flux. However, if an additional flux is introduced from the outside, e.g., by the magnetic field of the rotor coils, the transformer core of the rotor shaft must be dimensioned larger to conduct this additional flux without saturation. This negatively affects both the entire transformer package and the associated costs. To counteract this, it is known to provide an air gap or a plastic casing between the rotor shaft and the transformer, which, however, reduces the installation space available for the transformer and also makes manufacturing more complex. The present invention therefore deals with the problem of providing a rotor shaft for a separately excited synchronous machine with which the disadvantages known from the prior art can be overcome, at least in part. This problem is solved according to the invention by the subject matter of independent claim 1. Advantageous embodiments are the subject matter of the dependent claims. The present invention is based on the general concept of constructing a rotor shaft not from steel, as previously done, and with a plastic sleeve between the rotor shaft and a transformer arranged therein, but rather of constructing the rotor shaft in the transformer region from a paramagnetic material. This prevents the magnetic field generated in the rotor from penetrating inwards, since in this case the rotor shaft acts as a kind of shield between the rotor coils and the transformer arranged in a cavity of the rotor shaft. The rotor shaft according to the invention for a separately excited synchronous machine therefore has a first, hollow shaft section, which is at least partially constructed from a first material with a magnetic permeability of µr ~ 1. This design of the rotor shaft according to the invention allows the transformer, for example a ferrite core or a rectifier, to be arranged inside the rotor shaft, even though rotor coils generating a magnetic field are present in the same axial region outside the rotor shaft. By using the first material in the first shaft section of the rotor shaft according to the invention with a magnetic permeability of µr ~ 1, the magnetic conductivity in this first shaft section can be significantly reduced, whereby the magnetic field generated, for example, by the rotor coils radially outside the first shaft section does not enter a cavity of the first shaft section. penetrates and negatively affects a transformer located there, for example a rectifier or a ferrite core. In particular, there is no longer any need to fear that an additional magnetic flux caused by the rotor winding will lead to saturation of the transformer o