Rotor for an electrical machine with a solid central rotor element and method for producing such a rotor element

Abstract

The present invention relates to a rotor (1) for an electrical machine having a solid central rotor element. Furthermore, the invention relates to a method for producing such a rotor element. The rotor (1) according to the invention is preferably used in permanent magnet synchronous machines. The central rotor element comprises a rotor shaft (3) extending in an axial direction (Z), a rotor yoke (5), a first end plate (4a), and a second end plate (4b) spaced apart from the first end plate (4a) in the axial direction (Z). The rotor yoke (5) is formed between the two end plates (4a, 4b). The rotor yoke (5) has a plurality of recesses (6) distributed along a circumferential direction, the recesses (6) being open radially outward.wherein a laminated pole piece (7) in the axial direction (Z) and a permanent magnet arrangement with at least one permanent magnet (8) are arranged in the respective recess (6), wherein the at least one permanent magnet (8) of the permanent magnet arrangement is arranged in the radial direction (R) between the rotor yoke (5) and the laminated pole piece (7), wherein the rotor has a fiber bandage (9) for fixing the pole pieces (7) and the permanent magnets (8) in the recesses (6) of the central rotor element, wherein the fiber bandage (9) encloses the arrangement of the central rotor element, permanent magnets (8) and pole pieces (7) radially on the outside.

Description

[0001] The present invention relates to a rotor for an electrical machine with a solid central rotor element. Furthermore, the invention relates to a method for producing such a rotor element. The rotor according to the invention is preferably used in permanent magnet synchronous machines.

[0002] Electrical machines, such as motors and generators, are well known in automotive engineering. In permanent magnet electrical machines, the rotors typically comprise a rotor body, which can be solid or laminated with mutually electrically insulated iron laminations made of ferromagnetic material, e.g., a laminated core. The rotor body has an axis of rotation and an outer circumference, with several permanent magnets arranged in a radial region between the axis of rotation and the outer circumference.

[0003] In principle, it is also known from the prior art, for example from US 2023 / 0179045 A1, to use fiber sleeves to fix permanent magnets and pole pieces in a rotor body. DE102020216244A1, DE102023108508A1, CN1801577A, US 5,191,256, and US 2018 / 0102699 A1 disclose further prior art.

[0004] Electrical machines with a conventional rotor topology using buried permanent magnets typically use a laminated rotor to minimize core losses. Forces are typically transferred between various separate rotor components, such as the rotor shaft, the electrical lamination stack, and the end plates, via a shaft-hub connection based on frictional and / or positive locking. The positive locking is achieved, for example, by a lug on the electrical lamination and a groove in the rotor shaft. Generally, this concept is implemented with a one-sided stop for the rotor lamination stack on the rotor shaft. On the other side, the lamination stack is secured with a shaft nut and a locking washer. When using frictional connections, such as a shrink fit, the undersize must be able to transmit the torque at the maximum speed.

[0005] The use of fiber bandages to secure the permanent magnets and pole pieces requires a tight tolerance on the end plates, which in turn requires mechanical post-processing, such as grinding, of the end plates after they have been mounted on the rotor shaft. This additional manufacturing step is necessary to ensure the required form tolerance and thus ensure that the bandage can be installed properly and that the desired properties of the rotor are maintained.

[0006] The object of the present invention is to provide a rotor that is improved with regard to the use of a fiber sleeve or fiber bandage, which is characterized by simplified assembly. Furthermore, the object of the invention is to provide a manufacturing method for a central rotor element of the rotor according to the invention.

[0007] These problems are solved by the subject matter of the independent patent claims. Advantageous further developments are the subject matter of dependent claims.

[0008] The rotor according to the invention is a rotor for an electrical machine, in particular a rotor for a permanent magnet synchronous machine. The rotor has a central rotor element formed as a solid component, wherein the central rotor element has a rotor shaft extending in an axial direction, a rotor yoke, a first end plate, and a second end plate spaced apart from the first end plate in the axial direction. The rotor yoke is formed between the two end plates. The rotor yoke has a plurality of recesses distributed along a circumferential direction, the recesses being open radially outward. A pole piece laminated in the axial direction and a permanent magnet arrangement with at least one permanent magnet are arranged in the respective recess.wherein the at least one permanent magnet of the permanent magnet arrangement is arranged in the radial direction between the rotor yoke and the laminated pole piece, wherein the rotor has a fiber bandage for fixing the pole pieces and the permanent magnets in the recesses of the central rotor element, wherein the fiber bandage encloses the arrangement of the central rotor element, permanent magnets and pole pieces radially on the outside.

[0009] In contrast to an assembled component, which is created by assembling various components, a solid component requires no assembly. A solid component is understood, in particular, to be a one-piece or monolithic body made of a single material. A component consisting of components joined together, for example, by welding, gluing, pressing, or screwing, is not a solid component within the meaning of the present invention. In particular, a laminated component, i.e., a component comprising layered electrical iron sheets, such as laminated pole pieces, does not constitute a solid component.

[0010] By means of the design according to the invention, in particular by using the fiber bandage for fixing the laminated pole pieces and the permanent magnets in the recesses of the solid rotor yoke, it can be achieved that the laminated pole pieces and the central rotor element are not connected to one another via a magnetic material, such as iron webs, which has an advantageous effect on the reduction of the magnetic stray flux within the rotor, which leads to an improved utilization of the magnetic field in the air gap.

[0011] The number of recesses is at least two. It is considered advantageous if the number of recesses, and thus the number of magnetic poles, is an integer multiple of two, for example, six, eight, or ten.

[0012] By using a solid central rotor element and eliminating the laminated rotor yoke, it is possible to create a rotor design that can absorb forces particularly well in the axial direction. This allows for a reduction in the weight and inertia of the rotor, as 3D recesses (variable along the axis) can be implemented.

[0013] The elimination of the laminated rotor yoke and the combination of several typically separate components, such as the rotor shaft, rotor core, and end plates, leads to cost savings and reduces manufacturing effort. This is particularly advantageous because complex sheet metal processing processes (sheet metal punching, stacking, shrink-fitting, etc.) can be avoided for a large part of the rotor assembly.

[0014] The integration of the rotor shaft, end plates, and rotor yoke into a central component eliminates the need for a shaft-hub connection. This increases the stability and robustness of the rotor. The solid design eliminates the need for axial fixation, for example, with a shaft nut. This simplifies assembly and further reduces manufacturing costs.

[0015] It is considered particularly advantageous if the fiber bandage is designed as a carbon fiber bandage, in particular as a tangentially wound carbon fiber bandage with 0-degree fibers. This type of fiber bandage design is particularly effective at absorbing centrifugal forces at high rotor rotation speeds, since the fibers in this case redirect the radial forces into the tangential direction, with the individual fibers exhibiting particularly high tensile strength in this direction.

[0016] The fiber bandage is preferably made up of several layers.

[0017] In a particularly preferred embodiment, the fiber bandage is pressed axially onto the arrangement of the central rotor element, permanent magnets, and pole pieces. The use of the solid central rotor element is particularly advantageous here, since the central rotor element can be reworked before assembly of the rotor, in particular before the permanent magnets and the laminated pole pieces are inserted. In particular, the end plates can be reworked in order to maintain the tolerances required for assembly, in particular for axially pressing on the fiber bandage. In contrast, with an assembled central rotor element, there is the problem that reworking is necessary after the individual components have been assembled in order to maintain the necessary tolerances. This entails increased manufacturing costs.

[0018] In a particularly preferred development, it is provided that the separating webs have a cross-section that tapers radially outwards, preferably being conical.

[0019] In order to reduce the axial magnetic leakage flux in the end region of the rotor and at the same time to minimize the weight, in an advantageous further development the end plates have a plurality of through-openings penetrating the end plates in the axial direction, wherein these through-openings are aligned with the permanent magnets arranged in the recesses in the axial direction and are designed according to the shape and arrangement of the permanent magnets.

[0020] Preferably, the central rotor element consists of a soft magnetic material or a highly permeable iron material.

[0021] Preferably, the central rotor element is a cast part. Cast parts are particularly easy to manufacture and any subsequent machining can be carried out with ease.

[0022] Preferably, radially outer surfaces of the central rotor element have slots extending in the circumferential direction in order to reduce eddy current losses in the solid, thus unlaminated, central rotor element.

[0023] Given the particularly high mechanical integrity of the rotor, it is considered advantageous if at least some of the separating webs extend to an inner circumferential surface of the fiber bandage, so that the fiber bandage can be supported on these separating webs. Furthermore, this design facilitates the attachment of the fiber bandage.

[0024] With a view to reducing the weight of the central rotor element, a preferred embodiment provides for the rotor yoke, particularly in the area of ​​the separating webs, to have open and / or closed cavities, for example, in the form of slots or channels. It is also entirely conceivable for the central rotor element to have such cavities in the area of ​​the rotor shaft. The cavities can also be introduced, in particular, for balancing the rotor, or balancing can be achieved by deliberately introducing cavities.

[0025] It is quite conceivable that the design and / or arrangement of the cavities is asymmetrical.

[0026] According to the invention, the central rotor element is manufactured using a casting process or an additive manufacturing process. However, joining individual components of the central rotor element is not planned. Following the casting process or the additive manufacturing process, it is entirely conceivable that the central rotor element could be mechanically reworked to ensure compliance with manufacturing tolerances.

[0027] The additive manufacturing process could, for example, be a metal powder deposition process. The casting process could, for example, be a permanent mold casting process.

[0028] The following figures illustrate the invention in more detail using an exemplary embodiment, without being limited to this embodiment. They show: Fig. 1 a rotor according to the invention in a perspective view, Fig. 2 the rotor according to Fig. 1 in a partially sectioned representation in a perspective view as in Fig. 1, Fig. 3 the rotor according to Fig. 1 in a sectional view in a view along a rotor axis, Fig. 4 a solid, central rotor element of the rotor according to Fig. 1, Fig. 5 laminated pole pieces of the rotor according to Fig. 1 in a perspective view.

[0029] The Fig. 1 to 5 show a rotor 1 according to the invention or components of the rotor 1 according to the invention. The rotor 1 has a central rotor element 2 designed as a one-piece solid component. The central rotor element 2 is in the Fig.4 is shown in more detail. A rotor shaft 3 extending in the axial direction Z, a first end plate 4a, a second end plate 4b formed in the axial direction at a distance from the first end plate 4a, and a rotor yoke 5 formed in the axial direction Z between the two end plates 4a, 4b and circumferentially around the rotor shaft 2 are formed by the central rotor element 2.

[0030] The rotor yoke 5 has six recesses 6 that are regularly distributed along the circumferential direction of the rotor 1 and that are separated from one another in the circumferential direction of the rotor by separating webs 10 of the rotor yoke 5 that extend from radially inward to radially outward. The number of recesses 6 is six in the exemplary embodiment shown in the figures. The separating webs 10 taper from radially inward to radially outward, so that the recesses 6 widen from radially inward to radially outward. A permanent magnet arrangement and a pole piece 7 that is laminated in the axial direction Z are introduced into the respective recess 6. The permanent magnet arrangement comprises two permanent magnets 8 in each case, wherein the permanent magnets 8 of the respective permanent magnet arrangement are arranged in a V-shape.In principle, however, other variants of permanent magnet arrangements are also conceivable, for example, an arrangement with more or fewer than two permanent magnets and / or permanent magnet arrangements with a different arrangement of the permanent magnets instead of a V-shaped arrangement. For example, the permanent magnet(s) can also be arranged in a U-shape or I-shape. The permanent magnets 8 are arranged in the radial direction R between the pole pieces 7 and the rotor element 2.

[0031] In the present case, the laminated pole piece 7 comprises a plurality of iron sheet laminations which have a thickness of typically 0.15 mm to 0.35 mm and are electrically and / or magnetically separated from one another by an insulation layer formed between the individual sheet laminations.

[0032] The rotor 1 comprises a fiber bandage 9, which in this case is designed as a carbon fiber bandage. This fiber bandage 9 serves to fix the pole pieces 7 and the permanent magnets 8 in the recesses 6 of the central rotor element 2, wherein the fiber bandage 9 radially encloses the outer circumference of the arrangement formed by the central rotor element 2, the permanent magnets 8, and the pole pieces 7. In this case, the fiber bandage 8 extends in the axial direction Z over both the first end plate 4a and the second end plate 4b.

[0033] In the area of ​​the separating webs 10, the rotor yoke 5 can have a plurality of cavities 11, which extend essentially along the axial direction Z through the rotor yoke 5. These cavities 11 can certainly have a cross-section that changes along the axial direction Z.

[0034] In addition, the respective end plate 4a, 4b has a plurality of through-openings 12 passing through the respective end plate 4a, 4b in the axial direction Z, wherein these through-openings 12 are aligned with the permanent magnets 8 arranged in the recesses 6 in the axial direction Z and are designed according to the shape and arrangement of the permanent magnets 8, namely in the present case V-shaped. List of reference symbols 1 rotor 2 central rotor element 3 Rotor shaft 4a first end plate 4b second end plate 5 Rotor yoke 6 recess 7 Pole piece 8 permanent magnet 9 Fiber bandage 10 Divider 11 Cavity 12 passage opening Z axial direction R radial direction 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] US 2023 / 0179045 A1

[0003] DE 102020216244A1

[0003] DE 102023108508A1

[0003] CN 1801577A

[0003] US 5,191,256

[0003] US 2018 / 0102699 A1

[0003]

Claims

[1] Rotor (1) for an electrical machine, wherein the rotor (1) has a central rotor element (2) designed as a solid component, wherein the central rotor element (2) has a rotor shaft (3) extending in an axial direction (Z), a rotor yoke (5), a first end plate (4a) and a second end plate (4b) spaced apart from the first end plate (4a) in the axial direction (Z), wherein the rotor yoke (5) is formed between the two end plates (4a, 4b), wherein the rotor yoke (5) has a plurality of recesses (6) distributed along a circumferential direction, wherein the recesses (6) are open radially outwards, wherein a pole piece (7) laminated in the axial direction (Z) and a permanent magnet arrangement with at least one permanent magnet (8) are arranged in the respective recess (6),wherein the at least one permanent magnet (8) of the permanent magnet arrangement is arranged in the radial direction (R) between the rotor yoke (5) and the laminated pole piece (7), wherein the rotor (2) has a fiber bandage (9) for fixing the pole pieces (7) and the permanent magnets (8) in the recesses (6) of the central rotor element (2), wherein the fiber bandage (9) encloses the arrangement of the central rotor element (2), permanent magnets (8) and pole pieces (7) radially on the outside. [2] Rotor according to claim 1, wherein the fiber bandage (9) is designed as a carbon fiber bandage, in particular as a tangentially wound carbon fiber bandage with 0-degree fibers. [3] Rotor according to claim 1 or 2, wherein the fiber bandage (9) is pressed axially onto the arrangement of central rotor element, permanent magnets and pole pieces. [4] Rotor according to one of claims 1 to 3, wherein the fiber bandage (9) extends in the axial direction (Z) over the first end plate (4a) and / or the second end plate (4b). [5] Rotor according to one of claims 1 to 4, wherein the end plates (4a, 4b) have a plurality of through-openings (12) passing through the end plates (4a, 4b) in the axial direction (Z), wherein these through-openings (12) are aligned with the permanent magnets (8) arranged in the recesses (6) in the axial direction (Z) and are designed according to the shape and arrangement of the permanent magnets (8). [6] Rotor according to one of claims 1 to 5, wherein the central rotor element (2) consists of a soft magnetic material or a highly permeable iron material. [7] Rotor according to one of claims 1 to 6, wherein the central rotor element (2) is a cast part. [8] Rotor according to one of claims 1 to 7, wherein radially outer surfaces of the central rotor element (2) have circumferentially extending slots to reduce eddy current losses. [9] Rotor according to one of claims 1 to 8, wherein the rotor yoke (5), in particular in the region of the separating webs (10), has open and / or closed cavities (11). [10] Method for producing a central rotor element (2) of a rotor (1) according to one of claims 1 to 9, wherein the central rotor element (2) is produced by means of a casting process or by means of an additive manufacturing process.

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