Sleeve for a rotor

Abstract

Sleeve for a rotor (1) for an electrical machine, in particular for a gas supply device for supplying air to a fuel cell stack, wherein the rotor has at least one magnetic body (13) which is arranged in an axial direction (2) between a first (10) and a second shaft body (11) of the rotor, wherein the first shaft body (10), the magnetic body (13) and the second shaft body (11) are arranged one behind the other in the axial direction of the rotor, wherein the at least one magnetic body (13) has end faces (21, 22) arranged one behind the other in the axial direction (2), wherein the first end face (21) is aligned with the first shaft body (10) and the second end face (22) is aligned with the second shaft body (11), wherein the sleeve is designed to support orto protect against environmental influences, characterized in that the sleeve (12) has at least one opening (55).

Description

State of the art

[0001] The invention is based on a sleeve according to the class of the independent claim.

[0002] For example, in mobile fuel cell applications, air compressors are required to supply air to the cathode side of the fuel cells, as described in DE 20 2021 103 279 U1. Extremely fast-rotating electric motors are used. The rotor of such electric motors consists of a shaft with integrated magnets. These must be fixed to the shaft. Due to the high centrifugal forces, a sleeve is placed over the magnets to hold them in place.

[0003] On the one hand, such a sleeve should be as thin as possible in order to keep the air gap of the electrical machine small and the permeability high, and on the other hand, it should have a minimum thickness and a minimum degree of strength in order to securely hold the magnets at the extremely high speeds. Disclosure of the invention

[0004] The sleeve according to the invention with the characterizing features of the independent claim has the advantage, in contrast, of improving the magnetic flux flow when used in a rotor, so that a magnetic body surrounded by the sleeve in the rotor can be made smaller. In addition, less material is required for its manufacture than if the sleeve were designed as a solid tube.

[0005] The measures listed in the dependent claims enable advantageous further developments and improvements of the sleeve specified in the independent claim.

[0006] Advantageously, the sleeve is produced using a three-dimensional printing process, in which several such sleeves can be printed in parallel, particularly with regularly spaced perforations. The provision of such perforations also shortens the printing time required.

[0007] In particular when using a nickel-based alloy, especially Inconel, the advantages of the invention are particularly evident, since alloy material, especially Inconel, which is associated with considerable costs, can be saved in the manufacture of the sleeve. Short description of the drawings

[0008] Embodiments of the invention are illustrated in the drawing and explained in more detail in the following description.

[0009] It shows Fig. 1 a section of a rotor and Fig. 2 a support sleeve for such a rotor. Embodiments of the invention

[0010] Fig. 1 shows a substantially central section of a rotor 1 for an electrical machine, in particular for a gas supply device or an electric air compressor for supplying air to a fuel cell stack, with a magnetic body 13, which is arranged in an axial direction 2 between a first (10) and a second shaft body 11 of the rotor. The first shaft body 10, the magnetic body 13, and the second shaft body 11 are arranged one behind the other in the axial direction of the rotor, wherein the at least one magnetic body 13 has end faces 21, 22 arranged one behind the other in the axial direction 2. The first end face 21 is aligned with the first shaft body 10, and the second end face 22 is aligned with the second shaft body 11.

[0011] Each of the end faces 21, 22 partially rests directly on the adjacent shaft body 10, 11.

[0012] The magnetic body 13 is surrounded by a sleeve 12 for support and protection against environmental influences.

[0013] When the electric machine is designed as an electric air compressor for fuel cell applications, a compressor impeller for the air to be compressed and / or a turbine wheel for energy recovery from flowing exhaust gas of the fuel cell stack is arranged to the left and right of the magnetic body on the shaft bodies in a manner not shown in detail.

[0014] The shaft bodies 10, 11 are preferably made of a metallic material. The sleeve 12 is made of a non-magnetic, preferably metallic, material.

[0015] In detail, the shaft bodies 10, 11 each have, on their side facing the magnetic body 13, a region 24 or 25 with a stepped geometry such that the end faces 21, 22 of the magnetic body only partially rest on the adjacent shaft body 10 or 11. The stepped geometries are rotationally symmetrical to the axial direction 2 and each have a cylindrical wall-shaped projection 27 or 28, with a cylindrical end face 30 or 31 of the respective projection resting directly on the magnetic body 13.

[0016] Furthermore, the stepped geometries 24, 25 each comprise an outer circumferential step 33 or 34 such that the sleeve 12 can rest flush on the shaft bodies at its ends facing the shaft bodies 10, 11, so that the Fig. 1 shown section of the rotor 1 has a continuous cylinder surface.

[0017] In an alternative embodiment, such a rotor can also provide axially arranged cover disks between the shaft bodies and the magnetic body, so that the magnetic body is covered by such a cover disk in the axial direction towards the shaft bodies.

[0018] Fig.Figure 2 shows, in an upright position, the structure of a sleeve 12, which is rotationally symmetrical about its axial direction 2. It has a radially symmetrical recess in the form of a groove 51 at each edge of its outer circumference, which, during manufacture of the rotor, spring-actingly ensures rapid, preliminary fixing to the two shaft bodies before further joining of the assembled rotor components. A key feature of the sleeve is the provision of openings 55 in the outer surface of the sleeve, which, as shown in the present example, are preferably evenly distributed over the outer surface of the sleeve, preferably precisely in the area that surrounds the magnetic body 13 in the assembled state of the rotor.

[0019] This sleeve is preferably manufactured using a three-dimensional printing process. To ensure sufficient roundness for the stated application, the sleeve is printed vertically. The construction occurs layer by layer, whereby several sleeves can be printed simultaneously in a given print space of the 3D printing machine. The time and quantity of sleeve material required are reduced by the provision of the openings compared to a sleeve without openings. The design of the openings is determined by the required strength and the optimization of the magnetic flux in the installed state.

[0020] Alternatively, the sleeve can also be machined from a solid raw material. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 20 2021 103 279 U1

[0002]

Claims

[1] Sleeve for a rotor (1) for an electrical machine, in particular for a gas supply device for supplying air to a fuel cell stack, wherein the rotor has at least one magnetic body (13) which is arranged in an axial direction (2) between a first (10) and a second shaft body (11) of the rotor, wherein the first shaft body (10), the magnetic body (13), and the second shaft body (11) are arranged one behind the other in the axial direction of the rotor, wherein the at least one magnetic body (13) has end faces (21, 22) arranged one behind the other in the axial direction (2), wherein the first end face (21) is aligned with the first shaft body (10) and the second end face (22) is aligned with the second shaft body (11), wherein the sleeve is designed to surround the magnetic body (13) for support or protection against environmental influences, characterized bythat the sleeve (12) has at least one opening (55). [2] Sleeve according to claim 1, characterized by that the sleeve has several openings (55). [3] Sleeve according to claim 2, characterized by that the openings are arranged symmetrically. [4] Sleeve according to one of the preceding claims, characterized by that the opening(s) are arranged in an area intended to surround the magnetic body. [5] Sleeve according to claim 4, characterized by that the opening(s) are only arranged in the area. [6] Sleeve according to one of the preceding claims, characterized by that radial constrictions (51) are provided at the ends. [7] Sleeve according to one of the preceding claims, characterized by that it is made of a nickel-based alloy, in particular Inconel. [8] Method for producing a sleeve according to one of the preceding claims, characterized bythat the process is a printing process. [9] Method according to claim 8, characterized by that the printing process is three-dimensional. [10] Method according to claim 9, characterized by that the three-dimensional construction in the printing process takes place in a standing state of the sleeve. [11] Method according to one of claims 8 to 10, characterized by that several sleeves are produced at the same time. [12] Rotor (1) for an electrical machine, in particular for a gas supply device for supplying air to a fuel cell stack, with a sleeve according to one of claims 1 to 7. [13] Electrical machine, in particular a gas supply device for supplying air to a fuel cell stack, with a rotor (1) according to claim 12.

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