Bandage for an electric machine in multi-part design, magnet carrier with bandage, rotor and axial flux machine

Abstract

Magnet carrier (1) for a rotor (2) of an axial flux machine, comprising a main body (3) prepared to receive a plurality of magnets (4) in a magnet receiving area, wherein the main body (3) is radially outside the magnet receiving area, but spaced apart from the outer edge of the main body (3), connected to a bandage insert (5) separate from the main body (3), characterized in that the main body (3) is designed as a plastic body having reinforcing fibers, the bandage insert (5) is designed such that it has a higher elongation at break than an edge section (6) extending from the magnet receiving area to the outer edge of the main body (3), and the edge section (6) has a higher strength than the bandage insert (5) to compensate for the centrifugal forces.

Description

[0001] The invention relates to a magnet carrier for a rotor of an axial flux machine, comprising a main body configured to receive a plurality of magnets in a magnet-receiving area, wherein the main body is formed as a plastic body comprising reinforcing fibers. Furthermore, the invention relates to a rotor for an axial flux motor having a magnet carrier according to the invention, as well as to an axial flux machine having the rotor according to the invention.

[0002] A rotor of an electric rotary machine and an electric rotary machine equipped therewith are known from the prior art, for example from WO 2022 / 073533 A1. The rotor of the electric rotary machine comprises a plurality of magnets and, for fixing the magnets, a magnet carrier with which the magnets are positioned on a circumference relative to a hub of the rotor. The magnet carrier extends radially outward further than the magnets and has a first axial width on the circumference of the positioning of the magnets and forms a widened portion radially outside the magnets, which widened portion has a second axial width that is greater than the first axial width.

[0003] It is the object of the present invention to provide an improved magnet carrier in order to reduce the disadvantages of the known solutions, in particular to increase the rigidity of the magnet carrier or the rotor in the axial direction.

[0004] This object is achieved according to the invention in a generic magnet carrier in that the main body is connected radially outside the magnet receiving area, but spaced from the outer edge of the main body, to a bandage insert / bandage / retainer separate from the main body.

[0005] In other words, the invention relates to the rotor of an electrical machine, in particular an axial flux machine. This type of machine is known from various applications and has several special features and advantages when used, for example, as a traction machine for a vehicle. There are various basic designs or types of axial flux machines, which differ in the arrangement of the rotor and / or stator. The invention described below relates to the I arrangement and H arrangement. The I arrangement is defined by an internal rotor and the H arrangement by two external rotors. Various combinations of the two arrangements exist, with even more rotors and stators. The described invention can, in principle, be used for all arrangements, preferably in high-speed machines with a large diameter in a compact installation space.

[0006] The magnet carrier, also called bandage, already known in WO 2022 / 073533 A1, can also project in places in the axial direction, thereby partially, completely or further overlapping the mechanical air gap of the arrangement.

[0007] In addition, the stiffness of the bandage / magnet carrier affects its stability and / or the stress state of the entire disk at rotational speed. Bandage materials used for high stiffness are high-modulus (HM-CFRP fiber) or ultra-high-modulus (UHM-CFRP fiber) carbon fibers, which are endlessly wound in a matrix around the rotor or pressed onto it as a prefabricated or partially finished component.

[0008] In the solution presented here, to improve the stability / stiffness of the carrier material, a separate bandage insert is inserted radially outside the magnet receiving area but at a distance from the outer edge of the magnet carrier. This results in numerous advantages. Under suitable loading conditions, these materials exhibit above-average fatigue strength and a very high tolerable number of load cycles compared to other composite materials or metals. By inserting a bandage insert made of a HM-CFRP fiber or a UHM-CFRP fiber, the notch sensitivity of the magnet carrier / bandage can be reduced. Furthermore, stiffness jumps or jumps in the load of the wrapped magnets, the surrounding structure, and the magnet carrier can be alleviated or eliminated. Local effects that occur at high speeds and large diameters, i.e., overall at high power density, are reduced.The inherently relatively low stiffness of a disk in the axial direction, i.e., when subjected to centrifugal forces, can counteract disk deformation. By reducing or eliminating disk deformation, required clearances can be reduced, thus increasing the power density and efficiency of the axial flux machine.

[0009] The inventive solution to the problem is to improve the rigidity of the magnet carrier and thus of the entire rotor.

[0010] For this purpose, a magnet carrier for a rotor of an axial flux machine, comprising a main body configured to accommodate a plurality of magnets in a magnet-receiving area, is connected to a bandage insert. The main body is designed as a plastic body comprising reinforcing fibers. The bandage insert is designed as a separate component and is connected to the main body radially outside the magnet-receiving area but spaced apart from the outer edge of the main body.

[0011] The magnet carrier is therefore made of two separate components, which have different properties.

[0012] Advantageous embodiments are claimed in the subclaims and are explained in more detail below.

[0013] Advantageously, the main body is made of a different material than the bandage insert, so that the different material properties lead to different interactions. For example, the stiffness of the material and thus of the rotor can be improved if one of the two materials used has a higher stiffness than the other. Thus, different properties of the magnet carrier can be achieved with different material properties.

[0014] Preferably, the bandage insert is designed such that it has a higher transverse load capacity and / or higher tensile strength and / or higher elongation at break than an edge section extending from the magnet receiving area to the outer edge of the main body. This results in improved load introduction into the main body and the edge section of the main body. This is intended to mitigate local stress peaks and thus even out load introduction, as well as to create a good surface for the main body. The stiffness of the material used is of secondary importance. Only the longitudinal elongation at break of the material used is of great importance. The longitudinal elongation at break is approximately 55% above fiber volume content or 1% above.

[0015] To compensate for centrifugal forces, especially centrifugal force, the edge section preferably has a higher rigidity and / or higher strength than the bandage insert. This reduces the deformability of the magnet carrier / bandage in the radial direction, so that even at high speeds and large radii, the magnet carrier has high strength, ensuring the efficiency of the axial flux machine.

[0016] The edge section preferably has a T-shaped or rectangular cross-section. In the case of a T-shaped cross-section of the edge section, the magnet carrier receives an increased area moment of inertia on the radial outer side. This counteracts deformations resulting from the centrifugal forces acting on the rotor. This means that the magnet carrier is stiffened on its radial outer side by a T-shaped formation. This has the advantage of reducing the technical air gap between the rotor and stator, thus achieving a higher power density.

[0017] In an advantageous embodiment, the magnet receiving area is defined by the main body which is formed with two walls.

[0018] Advantageously, the main body and / or the bandage insert is provided by means of a glass and / or carbon fiber-permeated epoxy resin or vinyl resin matrix.

[0019] A carbon fiber that achieves a composite stiffness in the range of 250 GPa to 400 MPa, particularly preferably 350 MPa, and longitudinal tensile strengths in the range of 700 MPa to 1,200 MPa, particularly 1,130 MPa in longitudinal tensile strength and 800 MPa in split-disc strength, is preferred. Due to these properties, the longitudinal elongation at break is below 1%.

[0020] Preferably, the edge portion of the main body has a maximum height of 50% of the height of the magnet carrier in the radial direction.

[0021] The invention also relates to a rotor for an axial flux machine with a magnet carrier according to the invention.

[0022] Furthermore, the invention relates to an axial flux machine with a rotor according to the invention, which interacts with a stator during operation. Due to the design of the magnet carrier and the rotor, the air gap between the rotor and stator can be reduced to improve the efficiency of the axial flux machine. This results in a high power density of the axial flux machine.

[0023] The invention is explained in more detail below with the help of a drawing.

[0024] They show: Fig. 1 a rotor with a first embodiment of a magnet carrier according to the invention in a sectional view, and Fig. 2 a cross section through the magnet carrier Fig. 1 along line 2.

[0025] The figures are merely schematic and serve only to clarify the invention. The same elements are designated by the same reference numerals.

[0026] In the Fig. 1 shows a cross-sectional view of a rotor 2 according to the invention with a magnet carrier 1 according to the invention. The rotor 2 is designed, as is known, as the rotor 2 of an axial flux machine in an I-shape and thus as a round disk. The magnet carrier 1 has a rotation axis 7 and extends in a radial direction perpendicular to the rotation axis 7. The magnet carrier 1 has recesses in which magnets 4 are arranged. A bandage insert 5 is arranged radially outwardly delimiting the magnets 4. The bandage insert 5 is connected at its radially outer region to an edge section 6 of a main body 3. The edge section 6 of the main body 3 is T-shaped or has a T-shaped cross-section, which increases the rigidity of the magnet carrier 1.The T-shaped configuration of the edge region 6 of the main body 3 is designed such that the edge region 6 has a greater axial width at its radially outer edge and an axially smaller width at its side facing / connected to the bandage insert 5.

[0027] Fig. 2 shows a detailed view along a section line 2 of the sectional view of the rotor 2. The detailed view shows that the main body 3, or the edge region 6 of the main body 3, is made of a different material than the bandage insert 5. The bandage insert 5 can be used as a manufacturing aid for winding. List of reference symbols 1 magnetic carrier 2 rotors 3 main bodies 4 Magnet 5 bandage insert 6 Edge section 7 Rotation axis 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] WO 2022073533 A1 [0002, 0006]

Claims

[1] Magnet carrier (1) for a rotor (2) of an axial flux machine, comprising a main body (3) which is prepared to receive a plurality of magnets (4) in a magnet receiving area, wherein the main body (3) is designed as a plastic body comprising reinforcing fibers, characterized by that the main body (3) is connected radially outside the magnet receiving area, but spaced from the outer edge of the main body (3) to a bandage insert (5) separate from the main body (3). [2] Magnetic carrier (1) according to claim 1, characterized by that the bandage insert (5) is made of a different material than the main body (3). [3] Magnetic carrier (1) according to claim 1 or 2, characterized bythat the bandage insert (5) is designed in such a way that it deliberately has a higher transverse load capacity and / or higher tensile strength and / or a higher elongation at break than an edge section (6) extending from the magnet receiving area to the outer edge of the main body (3). [4] Magnetic carrier (1) according to claim 3, characterized by that the edge section (6) for compensating the centrifugal forces has a higher rigidity and / or higher strength than the bandage insert (5). [5] Magnetic carrier (1) according to claim 4, characterized by that the edge section (6) has a T-shaped or rectangular cross-section. [6] Magnetic carrier (1) according to one of claims 1 to 5, characterized by that the magnet receiving area is defined by the main body (3) which has a double wall there. [7] Magnetic carrier (1) according to one of claims 1 to 6, characterized bythat the main body (3) and / or the bandage insert (5) is provided by means of a glass and / or carbon fiber-permeated epoxy resin or vinyl resin matrix. [8] Magnetic carrier (1) according to one of claims 1 to 7, characterized by that the edge section (6) has a maximum of 50% of the magnet carrier height (1) in the radial direction. [9] Rotor (2) for an axial flux machine, with a magnet carrier (1) according to one of the preceding claims. [10] Axial flux machine with the rotor (2) according to claim 9, which cooperates with a stator during operation.

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