Protective sleeve for a rotor

Abstract

Protective sleeve (120) for a rotor (1) for an electric 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 oriented towards the first shaft body (10) and the second end face (22) towards the second shaft body (11), wherein the protective sleeve (120) is designed to support the magnetic body (13) or the second end face (22).for its protection from environmental influences, wherein the protective sleeve (120) is designed to surround the magnetic body (13) on the outside, characterized in that the protective sleeve (120) has a spiral body (122).

Description

State of the art

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

[0002] For example, in mobile fuel cell applications, electrically driven air compressors are required to supply the cathode side of the fuel cells with air, as described in DE 20 2021 103 279 U1. Extremely high-speed electric motors are used in this process. The rotor of such electric motors consists of a shaft with at least one integrated magnet. These magnets must be fixed to the shaft. Due to the high centrifugal forces, a sleeve is fitted over the magnets to hold and protect them.

[0003] Due to functional and thermal requirements, the material pairing of magnet and rotor sleeve, as well as appropriate dimensioning, is crucial for the speed stability and performance of the overall system. The magnet, which is pressed or shrunk into the rotor sleeve, and the rotor ends are joined, for example, by means of a weld; optimal concentricity is essential for the high rotational speeds that occur.

[0004] The requirements for the rotor or protective sleeve are diverse: non-magnetic material, high strength, very similar thermal expansion and contraction behavior to the magnet in a large temperature range from approximately -40°C to > +200°C, suitability for connection with the rotor ends, availability of the raw material in a suitable dimension on the market, manufacturability and, last but not least, cost-effectiveness.

[0005] These requirements severely restrict the design and selection of materials; the currently known materials and their very demanding machining from bar stock lead to very high costs. Disclosure of the invention

[0006] In contrast, the protective sleeve according to the invention has the advantage of avoiding both the correspondingly high material scrap costs and the equally high further processing costs, in contrast to its manufacture from a bar material, by using a spiral-shaped body for its production.

[0007] The measures listed in the dependent claims enable advantageous further developments and improvements of the protective sleeve specified in the independent claim. Brief description of the drawings

[0008] Exemplary embodiments of the invention are shown in the drawing and explained in more detail in the following description.

[0009] They show Fig. 1 a section of a rotor and Fig. 2 a protective sleeve according to the invention. Embodiments of the invention

[0010] Fig. Figure 1 shows a substantially central section of a rotor 1 for an electric 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 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 oriented towards the first shaft body 10, and the second end face 22 is oriented towards the second shaft body 11.

[0011] Each of the end faces 21, 22 lies partially directly on the respective adjacent wave body 10, 11.

[0012] The magnetic body 13 is surrounded by a sleeve 12 for support and protection against environmental influences. The sleeve 12 also provides the mechanical connection between the two shaft ends and contributes significantly to the stability and strength of the shaft.

[0013] In the design of the electric machine 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 on the shaft bodies to the left and right of the magnetic body 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 wave bodies 10, 11 each have a region 24 or 25 with a stepped geometry on their side facing the magnetic body 13, such that the end faces 21, 22 of the magnetic body only partially rest on the respective adjacent wave body 10 or 11. The stepped geometries are rotationally symmetrical with respect to the axial direction 2 and each has a cylindrical wall-shaped projection 27 or 28, wherein a cylindrical end face 30 or 31 of the respective projection can rest directly on the magnetic body 13, or alternatively, a disk-shaped support element (not shown) made of non-magnetic, preferably metallic, material can be arranged between the magnetic body 13 and the wave bodies 10 or 11.

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

[0017] Such a rotor can be provided in a manufacturing process in which the two shaft bodies 10, 11 and the magnetic body 13 are joined thermally or non-thermally in a common process step or in separate process steps, for example by metallurgical bonding. The joining preferably takes place including the support or protective sleeve 12.

[0018] This ensures that the magnetic body is protected against the very high centrifugal forces generated by the rotational speeds by 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 joined by means of a weld.

[0019] Fig. Figure 2 shows a sleeve 120 according to the invention in a cross-sectional side view, as it is used in place of a sleeve 12 consisting of a tube section in a rotor 1 according to Fig. 1 can be built in.

[0020] To avoid both the high material scrap costs and the equally high machining costs associated with manufacturing the rotor sleeve from tubular material or even solid bar stock, this sleeve 120 is manufactured using a spiral spring 122. The coils 123 of this spiral spring, as an example of the usability of a spiral body, preferably lie directly on top of each other, so that a closed sleeve shape is formed which, as such, surrounds an imaginary axis of symmetry 200, in particular in a rotationally symmetrical manner.

[0021] The individual coils are firmly connected to form a sleeve by means of welds or solder joints 130 or solder points 132. Fig. Figure 2 shows a connection at the upper edge made by a weld or solder seam 130 and at the lower edge made by weld or solder points 132. At least one weld or solder seam 130 or at least one series of weld or solder points 132 must be provided, preferably several such weld or solder seams and / or series of weld or solder points. Alternatively, substantially the entire outer circumference of the coil spring can be covered with weld or solder seams and / or weld or solder points.

[0022] In the manufacture of the spiral spring used, a round wire can optionally be used instead of the one described in [reference to previous text]. Fig. As shown in 2, a rectangular wire can also be used. QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] DE 20 2021 103 279 U1

[0002]

Claims

[1] Protective sleeve (120) for - a rotor (1) for an electric 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 oriented towards the first shaft body (10) and the second end face (22) towards the second shaft body (11), - wherein the protective sleeve (120) is designed to support the magnetic body (13) or to protect it from environmental influences, - wherein the protective sleeve (120) is designed to surround the magnetic body (13) on its outer circumference, characterized by , that the protective sleeve (120) has a spiral body (122). [2] Protective sleeve according to claim 1, characterized by that the spiral body is a spiral spring. [3] Protective sleeve according to one of the preceding claims, wherein the turns (123) of the spiral body (122) lie directly on top of each other such that a closed sleeve shape is formed. [4] Protective sleeve according to claim 3, characterized by , that the windings (123) are bonded together. [5] Protective sleeve according to claim 4, characterized by , that the windings (123) are welded and / or soldered together. [6] Protective sleeve according to claim 5, characterized by , that at least one weld and / or brazed joint (130) is provided. [7] Protective sleeve according to claim 5 or 6, characterized by, that at least a number of welding and / or soldering points (132) are provided. [8] Protective sleeve according to claim 6 or 7, characterized by , that the weld or solder seam (130) or the series of weld and / or solder points (132) runs parallel to an axis of symmetry (200) of the protective sleeve. [9] Protective sleeve according to any one of the preceding claims, characterized by that the spiral body is made of a non-magnetic material. [10] Protective sleeve according to any one of the preceding claims, characterized by that the spiral body is made of a metallic material. [11] Method for manufacturing a protective sleeve according to any one of the preceding claims, characterized by , that at least one spiral body (122) is provided. [12] Rotor (1) for an electric 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 oriented towards the first shaft body (10) and the second end face (22) towards the second shaft body (11), with a protective sleeve (120) surrounding the magnetic body (13) according to one of claims 1 to 10. [13] Method for manufacturing a rotor according to claim 12, characterized by, that the protective sleeve is manufactured according to claim 11.

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