Protective sleeve for a rotor

Abstract

A protective sleeve (12, 120) for a rotor (1) for an electrical machine, in particular for a gas supply device for supplying air to a fuel cell stack, comprising 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 protective sleeve (12, 120) is designed to support the magnetic body (13) orto protect it from environmental influences, the protective sleeve (12, 120) being designed for this purpose to surround the magnetic body (13) in the axial direction, characterized in that the protective sleeve is constructed from at least two partial sleeves (51, 53).

Description

State of the art

[0001] The invention is based on a protective 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 and protect them. Disclosure of the invention

[0003] The protective sleeve according to the invention, in contrast, has the advantage of simplified production and thus a cost-effective solution for the required thickness of the protective sleeve for a high-speed rotor of an electrical machine. The provision of at least two partial sleeves, i.e. the provision of at least a two-layer structure, reduces the wall thickness of the sleeves to be processed, namely the partial sleeves, by at least 50% compared to a single-layer production of a protective sleeve. The partial sleeves with a small wall thickness can be easily manufactured using standard tube manufacturing processes, for example by rolling a sheet and subsequent longitudinal welding and / or smooth tube drawing, i.e. the seamless drawing of a tube.

[0004] The measures listed in the dependent claims enable advantageous further developments and improvements of the protective sleeve specified in the independent claim. Short description of the drawings

[0005] Embodiments of the invention are illustrated in the drawing and explained in more detail in the following description.

[0006] It shows Fig. 1 a section of a rotor, Fig. 2 a radial cross-section of a protective sleeve and Fig. 3 a perspective view of another protective sleeve. Embodiments of the invention

[0007] 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.

[0008] Each of the end faces 21, 22 lies partially directly on the adjacent shaft body 10, 11. Alternatively, a (in Fig. 1 not shown) cover plate must be provided.

[0009] The magnetic body 13 is surrounded by a sleeve 12 for support and protection against environmental influences.

[0010] 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.

[0011] The shaft bodies 10, 11 are preferably made of a metallic material. The sleeve 12 is made of a non-magnetic, preferably metallic, material.

[0012] 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.

[0013] 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.

[0014] Such a rotor can be produced in a manufacturing process in which the two shaft bodies 10, 11 and the magnetic body 13 are thermally joined in a common process step or in separate process steps, for example, by a material-to-material bond. The joining preferably takes place with the support or protective sleeve 12 included.

[0015] This ensures that the magnetic body is protected against the extremely high centrifugal forces generated by the rotational speeds by means of a pressed-on or shrunk-on metallic, but non-magnetic sleeve. The magnetic body, pressed or shrunk into the protective sleeve, and the shaft bodies are connected by a welded joint.

[0016] The rotor has a connection (not shown in detail) on one or both sides for possible components (compressors, turbines, etc.) in the area of ​​the shaft body. Air bearings and / or rolling bearings are used as the bearing system. When axial bearings are used, and these bearings are designed as air bearings, a rotor typically has a flange area.

[0017] Fig. Figure 2 shows a radial cross-section of a protective sleeve 12 of the rotor 1. The protective sleeve is constructed from a partial sleeve 51 and another partial sleeve 53. Both partial sleeves are made of a high-strength, metallic, non-magnetic material, with the partial sleeve 51 completely and seamlessly surrounding the outer surface of the partial sleeve 53. The two tubes can be connected by shrinking or hydroforming. Internal high-pressure forming can also be used to calibrate the geometry of the partial sleeves before they are joined, if necessary, with regard to suitable dimensioning with respect to the magnetic body surrounding them in the installed state and / or with regard to suitable dimensioning in preparation for their joining to form the final state of the double-tube sleeve. The seamless joining of the two partial sleeves results in a high rigidity of the sleeve 12.

[0018] Fig. 3 shows an alternative protective sleeve 120 for the rotor 1 in perspective view. The protective sleeve 120 is also constructed from at least two partial sleeves 51 and 53, which, however, in contrast to the sleeve according to Fig.2, with the exception of peripheral areas, are arranged at a short distance from one another. The perspective view shows the protective sleeve in section at one end; therefore, some sleeve material is not shown for a better understanding of the sleeve structure, so that it can be seen that the short distance between the two partial sleeves leads to the formation of a closed cavity 60 within the protective sleeve 120. The cavity is enclosed on all sides because the two partial sleeves 51 and 53 are connected to one another at the edges, for example, in an annular connecting area 70, for example, pressed together. The same applies to the other end of the protective sleeve 120, the structure of which is not visible in detail due to the perspective view, but is analogous to the sectional view of the visible end.When choosing the alternative protective sleeve 120 for the rotor 1, for example, a spring effect can be used to clamp the magnetic body. 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] Protective sleeve (12, 120) for - a rotor (1) for an electrical machine, in particular for a gas supply device for supplying air to a fuel cell stack, comprising at least one magnetic body (13) 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 protective sleeve (12, 120) is designed to support the magnetic body (13) or to protect it from environmental influences, - wherein the protective sleeve (12, 120) is arranged for this purpose to surround the magnetic body (13) in the axial direction, characterized by that the protective sleeve is constructed from at least two partial sleeves (51, 53). [2] Protective sleeve according to claim 1, characterized by that the at least one partial sleeve (51) partially or completely surrounds the lateral surface of the at least one further partial sleeve (53). [3] Protective sleeve according to claim 1 or 2, characterized by that the partial sleeves (51, 53) surround a cavity (60) in an axially central region. [4] Protective sleeve according to one of claims 1 or 2, characterized by that the partial sleeves (51, 53) lie on top of one another without any gaps along their entire surface. [5] Protective sleeve according to one of the preceding claims, characterized by that the partial sleeves (51, 53) extend in the axial direction (2) from one end of the protective sleeve to the other end of the protective sleeve. [6] Protective sleeve according to one of the preceding claims, characterized by that the partial sleeves (51, 53) are integrally connected to one another. [7] Protective sleeve according to one of the preceding claims, characterized by that the partial sleeves (51, 53) are made of a non-magnetic material. [8] Protective sleeve according to one of the preceding claims, characterized by that the partial sleeves (51, 53) are made of a metallic material. [9] Method for producing a protective sleeve (12, 120) according to one of the preceding claims, characterized by that at least two partial sleeves (51, 53) are provided and that the at least two partial sleeves (51, 53) are connected to one another. [10] Rotor (1) for an electrical machine, in particular for a gas supply device for supplying air to a fuel cell stack, with 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), with a protective sleeve (12, 120) surrounding the magnetic body (13) according to one of claims 1 to 8.

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