Rotor of an electric machine

Abstract

The present invention relates to a rotor (1) of an electric machine (10) having a rotor body (2) which extends about a rotor axis (100), in particular a laminated core which has a plurality of magnet pockets (3) which extend through the rotor body (2) in the axial direction (200) relative to the rotor axis (100) and in which magnets (4), in particular permanent magnets, are arranged, characterized in that the respective magnet (4) has two respective strip-shaped raised edge layers (5) on a magnet upper side (4a) and / or magnet underside (4b) and has at least one respective direct cooling surface (6) recessed between the two edge layers (5), a cooling channel (7) is formed in the respective magnet pocket (3) on the respective direct cooling surface (6) of the magnet (4), which is provided for cooling the direct cooling surface (6) of the magnet (4) and through which a cooling fluid can flow from a hollow rotor shaft (8) in the axial direction (200), and the magnets (4) are clamped in the magnet pockets (3) at the edge layers (5), in particular being secured without molding compound.

Description

[0001] R.415550

[0002] - 1 -

[0003] Description

[0004] title

[0005] Rotor of an electric machine

[0006] State of the art

[0007] The present invention relates to a rotor of an electric machine.

[0008] Furthermore, the invention relates to an electric machine with such a rotor.

[0009] Electrical machines, such as permanent magnet synchronous machines, are known from the prior art. These machines, for example, have permanent magnets in their rotors. The permanent magnets must be rigidly fixed within the rotor body, and cooling of the permanent magnets during machine operation must be possible. For example, document JP2019-161750 A discloses a rotor of an electrical machine that can cool a magnet arranged in a rotor core. For this purpose, a rotor shaft is provided with a coolant channel to which a coolant is supplied. A rotor body is mounted on the rotor shaft, which is formed with a plurality of magnet pockets. Cooling channels are provided next to the magnet pockets, with a coolant distribution plate arranged centrally in the rotor body and forming a connecting channel between the rotor shaft and the respective cooling channels.

[0010] Document DE 102016218856 A1 discloses a method for manufacturing a rotor or stator of an electric motor, in which an adhesive coating is applied to individual magnets. The adhesive coating bonds the individual magnets to form a magnetic strip, which can then be inserted into a rotor body. After the adhesive coating has cured, a R.415550

[0011] -2 -

[0012] A material-bonded connection was created between the magnets and the rotor body to fix the magnets in the rotor body.

[0013] Disclosure of the invention

[0014] The rotor according to the invention does not have cooling channels solely within the rotor lamination; instead, the cooling channels are located directly against the magnets. This results in improved cooling performance for the magnets. Furthermore, thermal insulation of the magnets through full-surface bonding or transfer molding is avoided. This also improves the magnet cooling capabilities.

[0015] The rotor of an electric machine according to the invention comprises a rotor body extending around a rotor axis. The rotor body is, in particular, a laminated core. The rotor body has a plurality of magnet pockets extending axially through the rotor body with respect to the rotor axis. At least one magnet is arranged in each magnet pocket. The magnets are, in particular, permanent magnets.

[0016] Each magnet has a top and a bottom surface, which correspond in particular to the largest surface area of ​​the magnet. The magnets are, for example, cuboid or trapezoidal in shape, with the top and bottom surfaces being opposite each other. A narrow side is present between the top and bottom surfaces. In addition, each magnet preferably has axial end faces. Preferably, two strip-shaped raised surface layers are provided on the top and / or bottom surface of the magnet, with at least one direct cooling surface recessed between the two surface layers.

[0017] Within each magnet pocket, a cooling channel is formed at the respective direct cooling surface of the magnet. This channel is designed to cool the direct cooling surface of the magnet. The cooling channel is therefore primarily limited by the direct cooling surface. A cooling fluid flows axially through the cooling channel from a hollow rotor shaft. The cooling channel extends R.415550

[0018] - 3 -

[0019] thus, in particular along the axial direction, at least sectionally, preferably completely, through the rotor body.

[0020] The magnets are clamped in the magnetic pockets on the edge layers. Preferably, the magnets are fixed without molding compound. In one embodiment, the edge layers can also be designed to form a material-bonded connection with the rotor body.

[0021] The surface layers and the recessed direct cooling surface between them create a simple and cost-effective cooling channel. This allows for direct magnet cooling without the need for molding compound in the magnet pockets. The surface layers advantageously seal against any cooling fluid flowing within the cooling channel. Furthermore, it is preferred that the surface layers electrically insulate the magnet from the rotor body. The surface layers also allow the magnets to be clamped securely and ensure uniform force distribution during clamping. The magnet can therefore be fixed in the respective magnet pocket with a particularly strong frictional connection.

[0022] By avoiding a full-surface insulating coating, particularly by attaching the magnets without an epoxy coating, thermal insulation of the magnets is avoided or at least minimized. This allows for reliable cooling of the magnets, especially with high cooling capacities.

[0023] The dependent claims describe preferred embodiments of the invention.

[0024] The respective edge layer of the magnets is preferably an adhesive film, adhesive tape, or coating. The adhesive film or tape is preferably applied to the top and bottom surfaces of the magnet. This simplifies the application of the edge layer.

[0025] The respective outer layer is preferably designed to be electrically insulating.

[0026] This allows the magnet to be electrically isolated from the rotor body. This particularly prevents short circuits between individual lamination layers when the rotor body is designed as a laminated core. The outer layer is preferably a plastic, in particular polyimide, polyamide-imide, or PEEK. R.415550

[0027] - 4 -

[0028] The respective edge layer preferably extends at an angle to the narrow side of the magnet. It is particularly advantageous if the edge layer is connected to an edge layer on the opposite top or bottom surface of the magnet. This simplifies the assembly of the edge layers. The edge layers are preferably attached using a tape or film as described, wherein the tape or film is applied to the top or bottom surface of the magnet and then folded over the narrow side to the opposite side of the top or bottom surface. This allows magnets to be provided with edge layers simply and cost-effectively.

[0029] The magnetic pocket advantageously features at least one channel recess on the respective direct cooling surface of each magnet to enlarge the cooling channel. This allows the cooling channel to transport a larger quantity of cooling fluid, resulting in improved cooling performance. The thickness of the surface layers can be minimized in this case, leading to optimal magnetic flux.

[0030] Preferably, several magnets are arranged axially one behind the other in the respective magnet pocket. The axially arranged magnets are preferably connected by the outer layers to form a magnetic unit. It is particularly advantageous that an axial gap is formed between adjacent magnets of the magnetic unit. A spacer element is arranged in this axial gap. The axial gap serves, in particular, as an insulating gap. The magnetic unit can be inserted into the respective magnet pocket easily and with minimal effort, so that the multiple magnets can be easily inserted into the rotor body. If the outer layers are preferably designed as a tape or film, this tape or film can be easily applied, for example, unrolled, onto the axially arranged magnets to combine them into the magnetic unit.

[0031] The clamping of the magnets is achieved in particular by a pre-stressed rotor sleeve. Alternatively or additionally, the clamping of the magnets is preferably achieved by expanding the rotor body, in particular by a rotor shaft or by an expandable material in the surface layers of the R.415550.

[0032] -5 -

[0033] Magnets are reached. This ensures reliable clamping, which reliably holds the magnets in the rotor body.

[0034] The rotor body has, in particular, rotor poles, each with a pole center axis. At least one of the rotor poles contains at least one magnet layer comprising at least one magnet. To form a radial clamping of the magnets, each magnet layer comprises only a single magnet pocket. This magnet pocket preferably has no central rib facing the pole center axis. The magnet pocket thus extends, in particular symmetrically to the pole center axis, between the two pole halves.

[0035] The magnetic pockets are preferably closed by a circumferential rib located on the outer circumference of the rotor body. This ensures a secure hold of the rotor body at the corresponding poles.

[0036] Alternatively, the magnetic pockets are preferably designed to be open towards the outer circumference of the rotor body. This minimizes magnetic stray fluxes.

[0037] The upper and lower surfaces of the magnets are preferably aligned perpendicular to the pole center axis of the respective rotor pole. This allows for optimal clamping of the magnets and thus optimal hold within the rotor body.

[0038] The respective magnet pocket is permeable to the cooling fluid for cooling the rotor, and preferably at least one cooling path is formed within each magnet pocket. Two axially opposing cooling paths are particularly advantageous within each magnet pocket. The cooling path of each magnet pocket can be supplied with cooling fluid via a radial supply path that connects the hollow rotor shaft to the respective magnet pocket. This allows for effective cooling of the magnets. The supply of the cooling fluid is via a hollow shaft and is therefore simple and reliable to implement.

[0039] The radial supply path advantageously opens via at least one inlet disk of the rotor body into a part of the respective magnet pocket that is central with respect to the pole center axis. From the opening into the magnet pocket, the supply path leads via branch channels into the cooling channels to R.415550.

[0040] - 6 -

[0041] Cooling of the direct cooling surfaces. This allows the cooling fluid to be reliably distributed to the individual cooling channels. The inlet disk is located in the axially central part of the rotor body.

[0042] The rotor pole preferably has a radially inner magnet layer and a radially outer magnet layer in the radial direction with respect to the rotor axis. The radially inner magnet layer has at least two magnets arranged on both sides of the pole's central axis, spaced apart from each other to form an intermediate channel. In particular, the intermediate channel is formed along the pole's central axis. Preferably, the two magnets of the radially inner magnet layer are also arranged symmetrically with respect to the pole's central axis. The radially outer magnet layer has at least one magnet. In this way, the magnetic mass is optimally distributed within the rotor body to achieve maximum magnetic flux with minimal material usage, while simultaneously enabling optimal clamping and cooling of the magnets.

[0043] The radial supply path particularly preferably has a first radial section that leads centrally into the radially inner magnet layer.

[0044] Furthermore, the radial supply path has a second radial section that leads from the intermediate channel centrally into the radially outer magnet layer. This ensures that the cooling fluid is reliably delivered to all magnet layers.

[0045] The rotor body is preferably designed as a stacked laminated core consisting of several standard laminations and several special laminations. The standard laminations form the magnet pockets. In addition to the magnet pockets, the special laminations also form radial sections of the supply path from a rotor shaft to the magnet pockets. The special laminations have, in particular, rotationally symmetrical first radial sections of the supply path, each of which is fluidly connected to a magnet pocket, and second radial sections of the supply path, each of which is connected to a shaft seat for receiving the rotor shaft. It is preferably provided that at least two adjacent special laminations are twisted relative to each other, such that a first radial section is fluidly connected to a second radial section. In this way, the supply path from the rotor shaft to the magnet pocket is formed. R.415550

[0046] - 7 -

[0047] The invention also relates to an electric machine. In particular, the electric machine is a permanent magnet synchronous motor. The electric machine has a rotor as described above. Furthermore, the electric machine has a stator designed to drive the rotor. The stator comprises, in particular, a stator winding that interacts with the magnets of the rotor.

[0048] Brief description of the drawings

[0049] Exemplary embodiments of the invention are described in detail below with reference to the accompanying drawings. The drawing shows:

[0050] Figure 1 shows a schematic representation of an electric machine according to an embodiment of the invention.

[0051] Figure 2 shows a schematic representation of a magnet unit of the electric machine according to the embodiment of the invention.

[0052] Figure 3 shows a schematic representation of a first alternative rotor design of the electric machine according to the embodiment of the invention.

[0053] Figure 4 shows a schematic representation of a second alternative rotor design of the electric machine according to the embodiment of the invention.

[0054] Figure 5 shows a schematic sectional view of the rotor of the electric machine according to the embodiment of the invention.

[0055] Figure 6 is a schematic perspective view of the rotor of the electric machine according to the embodiment of the invention, R.415550

[0056] - 8 -

[0057] Figure 7 shows a schematic representation of a first sheet metal lamella of a rotor body of the rotor of the electric machine according to the embodiment of the invention, and

[0058] Figure 8 shows a schematic representation of a second sheet metal lamella of the rotor body of the rotor of the electric machine according to the embodiment of the invention.

[0059] Embodiments of the invention

[0060] Preferably, all identical components, elements and / or units in all figures are provided with the same reference numerals.

[0061] Figure 1 schematically shows an electric machine 10 according to an embodiment of the invention. The electric machine 10 has a rotor 1 and a stator 11, which is designed to drive the rotor 1.

[0062] The rotor 1 of the electric machine 10 has a rotor body 2 extending around a rotor axis 100, which is in particular a laminated core. The rotor axis 100 is preferably an axis of rotation of the rotor 1 and in particular a central axis of the electric machine 1. An axial direction 100 is defined along the rotor axis 100, and a radial direction 300 is defined perpendicular to it.

[0063] The rotor body 1 has a plurality of magnet pockets 3 extending axially 200 through the rotor body 2 with respect to the rotor axis 100. Magnets 4, which are in particular permanent magnets, are arranged in the magnet pockets 3. The rotor body 2 is mounted on a rotor shaft 8. The rotor shaft 8 is hollow and serves to supply a cooling fluid, which will be explained later. The rotor shaft 8 is supported, in particular, for rotation about the rotor axis 100.

[0064] In each magnetic pocket 3, several magnets 4 are arranged one behind the other in the axial direction 200. As shown in Figure 2, these magnets 4 are connected to form a magnetic unit 12. For this purpose, the magnets 4 each have two strip-shaped raised edge layers 5 on a magnet top surface 4a and / or magnet bottom surface 4b. The respective edge layer 5 extends

[0065] - 9 -

[0066] The magnet 4 is angled to the narrow side 4c of the respective magnet and is connected to an edge layer 5 on the opposite magnet top 4a or magnet bottom 4b. This results in a U-shape of the two connected edge layers 5 on the magnet top 4a and magnet bottom 4b. The magnets 4 connected to the magnet unit 12 are easy to handle and can be inserted easily and reliably into the respective magnet pocket 3.

[0067] The respective outer layer 5 is, for example, an adhesive film, adhesive tape, or coating. The outer layer 5 is electrically insulating and comprises, in particular, polyimide and / or polyamide-imide and / or PEEK. The magnets 4 are in contact with the rotor body 2 via the outer layers 5. This provides electrical insulation for the magnets 4 from the rotor body 2. A short circuit between the laminations of the rotor body 2, which is designed as a laminated core, is thus prevented.

[0068] Between the outer layers 5 of the magnet's upper surface 4a and between the outer layers 5 of the magnet's lower surface 4b, a recessed direct cooling surface 6 is provided. This serves to directly cool the magnet 4, as shown in particular in Figure 3 and Figure 4.

[0069] Figure 3 shows a first alternative rotor design for rotor 1. Figure 4 shows a second alternative rotor design for rotor 1. In both cases, a cooling channel 7 is formed in the respective magnet pocket 3 at the respective direct cooling surface 6 of the magnet 4. The cooling channel 7 is designed to cool the direct cooling surface 6 of the magnet 4 and is permeable to a cooling fluid flowing from the hollow rotor shaft 8 in the axial direction 200.

[0070] The rotor body basically has two rotor poles 14, each with a pole center axis 14a. Figures 3 and 4 each show a portion of such a rotor pole 14. Each rotor pole 14 comprises several magnet layers 20a, 20b, and, in the radial direction 300 with respect to the rotor axis 100, a radially inner magnet layer 20b and a radially outer magnet layer 20a. The radially outer magnet layer 20a has one magnet 4. The radially inner magnet layer 20b has two spaced-apart magnets 4. Both magnet layers 20a, 20b each comprise only a single magnet pocket 3 to receive the magnets 4.

[0071] - 10 -

[0072] The central web faces the pole center axis 14a. When the description of the magnet layers 20a, 20b refers to one or two magnets, this refers to the cross-section perpendicular to the rotor axis 100. It is irrelevant whether several magnets 4 are arranged one behind the other in the axial direction 200, so that the reference to one or two magnets is not to be understood in relation to the axial direction 200, but only within the cross-section perpendicular to the rotor axis 100.

[0073] The upper surfaces 4a and lower surfaces 4b of the magnets 4 are aligned perpendicular to the pole center axis 14a of the respective rotor pole 14. The magnets 4 are cuboid in shape. This allows for optimal radial clamping of the magnets 4. The magnets 4 are clamped in the magnet pockets 3 at the outer layers 5 and are thus fixed without molding compound. This avoids thermal insulation of the magnets 4 by a molding compound. Furthermore, the magnets 4 can be removed relatively easily from the rotor body 2 for recycling purposes. The clamping of the magnets 4 is achieved, for example, by a pre-tensioned rotor sleeve 13, by expanding the rotor body 2 by the rotor shaft 8, or by an expandable material in the outer layers 5 of the magnets 4.

[0074] By forming the cooling channels 7 directly on the direct cooling surfaces 6, the respective magnet 4 is optimally cooled. Preferably, the outer layers 5 seal the cooling channel 7 against the cooling fluid. The cooling channels 7 can be formed in different ways. The first variant, shown in Figure 3, demonstrates that the respective magnet pocket 3 on the respective direct cooling surface 6 of the respective magnet 4 has at least one channel recess 9 to enlarge the cooling channel 7. This allows for very thin outer layers 5, resulting in optimal magnetic flux.

[0075] In the second alternative according to Figure 4, the boundary layers 5 are thicker, and there are no channel recesses 9 as in Figure 3. Therefore, an additional recess in the rotor body 2 is not required. R.415550

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[0077] In all cases, a cooling channel 7 is preferably formed on both the upper surface 4a and the lower surface 4b of the magnet. This ensures reliable cooling of the magnets 4, thereby reducing the risk of overheating.

[0078] In the illustrated embodiment, the magnetic pockets 3 are closed by a circumferential web 15 located on the outer circumference 2a of the rotor body 2. This increases the stability of the rotor body 2. Alternatively, the magnetic pockets 3 can also be open towards the outer circumference 2a of the rotor body 2, in which case the rotor body 2 is held together in particular by the rotor sleeve 13.

[0079] As shown in Figures 5 and 6, the respective magnet pockets 3 are permeable to the cooling fluid for cooling the rotor 1. For this purpose, two cooling paths 16 opposite each other in the axial direction 200 are formed. The cooling paths 16 begin, in particular, at an axial center of the rotor body 2 and extend axially outwards. Each cooling path 16 of the respective magnet pocket 3 can be supplied with cooling fluid via a radial supply path 17. The radial supply path 17 connects the hollow rotor shaft 8 to the respective magnet pocket 3.

[0080] The radial supply path 17 preferably opens via at least one inlet disk 18 of the rotor body 2 into a part of the respective magnet pocket 3 that is central with respect to the pole center axis 14a. From there, the supply path 17 leads via branch channels into the cooling channels 7 for cooling the direct cooling surfaces 6. The inlet disk 18 is arranged in an axially central part of the rotor body 2 and is formed, for example, by several stacked special lamellae 21, as will be explained later with reference to Figure 7.

[0081] The supply path 17 has a first radial section 19a that opens centrally into the radially inner magnet layer 20b. As previously described, the radially inner magnet layer 20b has two magnets 4 arranged at a distance from each other on both sides of the pole center axis 14a to form an intermediate channel 18. The magnets 4 of the radially inner magnet layer 20b are mounted symmetrically with respect to the pole center axis 14a in the two pole halves 14b.

[0082] - 12 -

[0083] The radial supply path 17 also has a second radial section 19b. The second radial section 19b extends from the intermediate channel 18 and opens centrally into the radially outer magnet layer 20a. Thus, each magnet pocket 3 can be supplied with the cooling fluid.

[0084] The rotor body 2 is designed, for example, as a stacked laminated core consisting of several standard laminations 22 and several special laminations 21. A special lamination 21 is shown in Figure 7, and a standard lamination 22 is shown in Figure 8. The standard laminations 22 have pocket recesses 23 which, when the laminations 21, 22 are stacked, form the magnet pockets 3. There are two separate pocket recesses 23 per rotor pole 14 to form the two magnet pockets 3 for the radially inner magnet layer 20b and the radially outer magnet layer 20a.

[0085] The special lamellae 21 have, in addition to the pocket recesses 23, first radial recesses 24, second radial recesses 25, and third radial recesses 26. The first radial recesses 24 extend radially outwards from the rotor shaft 8. The second radial recesses 25 extend radially inwards from the inner pocket recess 23. The third radial recess 26 runs radially between two pocket recesses 23, in particular the inner pocket recess 23 and the outer pocket recess 23 of the respective rotor pole 14.

[0086] The special lamellae 21 are all identical and rotationally symmetrical. If the special lamellae 21 are stacked in a twisted position, a first radial recess 24 of one special lamella 21 is always fluidly connected to a second radial recess 25 of an adjacent special lamella 21 in the stack. In this way, the first radial section 19a of the supply path 17 from the rotor shaft 8 to the magnet pocket 3 is formed. The third radial recesses 26 form the second radial section 19b of the supply path 17.

Claims

R.415550 - 13 - Claims 1. Rotor (1) of an electric machine (10) comprising a rotor body (2) extending about a rotor axis (100), in particular a laminated core comprising a plurality of magnet pockets (3) extending axially (200) through the rotor body (2) with respect to the rotor axis (100) and in which magnets (4), in particular permanent magnets, are arranged, characterized by the fact that - the respective magnet (4) has two strip-shaped raised edge layers (5) on a magnet top (4a) and / or magnet bottom (4b) and at least one direct cooling surface (6) recessed between the two edge layers (5), - a cooling channel (7) is formed in the respective magnet pocket (3) at the respective direct cooling surface (6) of the magnet (4), which is provided for cooling the direct cooling surface (6) of the magnet (4) and through which a cooling fluid can flow from a hollow rotor shaft (8) in the axial direction (200) and - the magnets (4) are clamped in the magnetic pockets (3) at the edge layers (5), in particular fixed without molding compound.

2. Rotor (1) according to claim 1, characterized in that the respective edge layer (5) is an adhesive film, an adhesive tape or a coating.

3. Rotor (1) according to one of the preceding claims, characterized in that the respective outer layer (5) is electrically insulating, in particular comprising polyimide, polyamideimide or PEEK.

4. Rotor (1) according to one of the preceding claims, characterized in that the respective edge layer (5) extends angularly to the narrow side (4c) of the respective magnet (4) and is in particular connected to an edge layer (5) on the opposite magnet top (4a) or magnet bottom (4b). R.415550 - 14 - 5. Rotor (1) according to one of the preceding claims, characterized in that the magnet pocket (3) has at least one channel recess (9) for enlarging the cooling channel (7) on the respective direct cooling surface (6) of the respective magnet (4).

6. Rotor (1) according to one of the preceding claims, characterized in that several magnets (4) are arranged one behind the other in the respective magnet pocket (3) in the axial direction (200) and are connected by the edge layers (5) to form a magnet unit (12).

7. Rotor (1) according to one of the preceding claims, characterized in that the clamping of the magnets (4) is achieved by a pre-tensioned rotor sleeve (13) or by expanding the rotor body (2) by a rotor shaft (8) or by an expandable material in the outer layers (5) of the magnets (4).

8. Rotor (1) according to one of the preceding claims, characterized in that the rotor body (2) has rotor poles (14) each with a pole center axis (14a), wherein at least one magnet layer (20a, 20b) comprising at least one magnet (4) is provided in at least one of the rotor poles (14), wherein the respective magnet layer (20a, 20b) comprises only a single magnet pocket (3) to form a radial clamping of the magnets (4), which in particular does not have a central web facing the pole center axis (14a).

9. Rotor (1) according to one of the preceding claims, characterized in that the magnet pockets (3) are closed by a circumferential web (15) located on the outer circumference (2a) of the rotor body (2) or are open towards the outer circumference (2a) of the rotor body (2).

10. Rotor (1) according to claim 8 or 9, characterized in that the upper surfaces (4a) and lower surfaces (4b) of the magnets (4) are aligned perpendicular to the pole center axis (14a) of the respective rotor pole (14). R.415550 - 15 - 11. Rotor (1) according to one of the preceding claims, characterized in that the respective magnet pocket (3) is permeable to the cooling fluid for cooling the rotor (1), wherein at least one cooling path (16), in particular two cooling paths (16) opposite in the axial direction (200), are formed in the respective magnet pocket (3), wherein the cooling path (16) of the respective magnet pocket (3) can be supplied with cooling fluid via a radial supply path (17) which connects the hollow rotor shaft (8) to the respective magnet pocket (3).

12. Rotor (1 ) according to claim 11 , characterized in that the radial supply path (17) opens into a part of the respective magnet pocket (3) central with respect to the pole center axis (14a) via at least one inflow disk (18) of the rotor body (2), which is arranged in particular in an axially central part of the rotor body (2) and leads from there via branch channels into the cooling channels (7) for cooling the direct cooling surfaces (6).

13. Rotor (1) according to claim 11 or 12, the rotor pole (14) in the radial direction (300) with respect to the rotor axis (100) comprises a radially inner magnet layer (20b) and a radially outer magnet layer (20a), wherein the radially inner magnet layer (20b) has at least two magnets (4) which are arranged to form an intermediate channel (18) at a distance from each other on both sides of the pole center axis (14a), in particular symmetrically to the pole center axis (14a), and wherein the radially outer magnet layer (20a) has at least one magnet (4).

14. Rotor (1) according to claim 13, characterized in that the radial supply path (17) has a first radial section (19a) which opens centrally into the radially inner magnet layer (20b), and a second radial section (19b) which opens centrally from the intermediate channel (18) into the radially outer magnet layer (20a).

15. Electric machine (10) comprising a rotor (1) according to one of the preceding claims and a stator (11) designed to drive the rotor (1).

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