Rotor arrangement and method for manufacturing a rotor arrangement

Abstract

A rotor assembly for an electric motor vehicle and a method for manufacturing the rotor assembly are provided. The rotor assembly comprises a hollow rotor shaft that extends axially at least over the length of the rotor assembly and has radially arranged coolant outlet openings. Two rotor lamination stacks and a disc-shaped heat sink arranged between the at least two rotor lamination stacks are also provided, wherein coolant passage channels are formed in the rotor lamination stacks and in the disc-shaped heat sink. The rotor assembly further comprises a first support disk and a second support disk, which are arranged at respective end faces of the rotor assembly and enclose the at least two rotor lamination stacks, wherein the first and the second support disks have outlet openings.The rotor arrangement is characterized in that the disc-shaped cooling element is arranged over the radially arranged coolant outlet openings of the rotor hollow shaft in such a way that a coolant from the rotor hollow shaft flows through the coolant passage channels of the disc-shaped cooling element and the rotor lamination stacks in the direction of the outlet openings of the first and second support disk and exits.

Description

[0001] The present disclosure relates to a rotor assembly for an electric machine and / or a method for manufacturing a rotor assembly for an electric machine. Additionally or alternatively, an electric machine having a rotor assembly according to the disclosure and / or a motor vehicle having the electric machine according to the disclosure are provided.

[0002] Modern motor vehicles, especially automobiles, increasingly incorporate electrical machines (motors and / or generators) that convert electrical energy into kinetic energy (drive) or vice versa (generator operation). In electric, semi-electric, or hybrid motor vehicles, electrical machines are used as prime movers to propel the vehicle by converting electrical energy from the vehicle's energy storage device, often a high-voltage storage device, into torque and motion.

[0003] Electric machines can be cooled via cooling channels in the housing, which corresponds to a "dry machine." Alternatively, the electric machine can be cooled using oil inside the electric machine, which cools the surfaces of the components inside the build space by centrifuging and then pumping, which corresponds to a "wet machine."

[0004] In a "dry machine," the components can only be cooled indirectly via heat conduction due to the spatial separation. In a "wet machine," the cooling medium only reaches the outer surfaces of the components of the rotor and stator assembly. Internal components, such as laminated cores, magnets, and coils, are not cooled by the oil.

[0005] Document US 2019 / 026 7859 A1 relates to a rotor of a rotating electrical machine which is cooled by a coolant.

[0006] Document JP 2019-170150 A relates to a rotor of an electric rotary machine capable of cooling a magnet from the inside of a rotating core.

[0007] Document WO 2020 / 174 176 A1 relates to a rotating electrical machine with a cooling circuit through the rotor shaft, with which the magnets of the rotor can be cooled.

[0008] Against the background of this prior art, it is an object of the present disclosure to provide a rotor arrangement for an electrical machine and / or a method for producing a rotor arrangement of an electrical machine, each of which is suitable for enriching the prior art.

[0009] The problem is solved by the features of the independent claims. The subordinate claims and the dependent claims each contain optional developments of the disclosure.

[0010] The problem is then solved by a rotor arrangement for an electric machine of a motor vehicle.

[0011] The rotor assembly has a hollow rotor shaft which extends axially at least over the length of the rotor assembly and has radially arranged coolant outlet openings.

[0012] Furthermore, the rotor arrangement has at least two rotor lamination stacks and a disc-shaped heat sink arranged between the at least two rotor lamination stacks, wherein coolant passage channels are formed in the rotor lamination stacks and in the disc-shaped heat sink.

[0013] In addition, a first support disk and a second support disk are provided, which are arranged on a respective end face of the rotor arrangement and enclose the at least two rotor laminated cores, wherein the first support disk and the second support disk have outlet openings.

[0014] The disc-shaped heat sink is arranged above the radially arranged coolant outlet openings of the hollow rotor shaft in such a way that a coolant coming from the hollow rotor shaft flows through the coolant passage channels of the disc-shaped heat sink and the rotor laminated cores in the direction of the outlet openings of the first and second support discs and exits.

[0015] For the purposes of the present disclosure, a disc-shaped heat sink can be a body that has the shape of a disc or a flat, round body. The disc-shaped heat sink can have two flat contact and support surfaces. The two flat contact and support surfaces can be in contact with the laminated cores of the rotor assembly. The disc-shaped heat sink can have a central bore for receiving the hollow rotor shaft. Coolant inlet openings can be formed on the inner wall of the central bore. Coolant inlet openings can be openings in the disc-shaped heat sink that are connected to coolant passageways.

[0016] For the purposes of the present disclosure, a rotor core may refer to an arrangement of thin, laminated sheet metal plates or strips that can be stacked and bonded together in a specific pattern. These sheet metal plates may consist of or comprise electrically conductive material, such as silicon iron. This can reduce eddy current losses in the electrical machine.

[0017] For the purposes of the present disclosure, a support disk may refer to a structural component configured to provide support, alignment, or stability to the faces of a rotor assembly of an electric machine.

[0018] The rotor arrangement described above offers a number of advantages. Among other things, the rotor arrangement enables particularly effective and direct cooling of hot spots in the rotor arrangement (in particular the rotor) and the stator by means of a disc-shaped heat sink and by means of holes and channels in the rotor lamination and the adjacent components, in particular the stator winding heads. At the same time, the disclosed design and positioning of the holes and channels does not adversely affect the electromagnetic design or other technical disciplines of the design and construction, or even the assembly of the rotor arrangement. Efficient cooling can increase the performance or continuous power of the electrical machine, and in the case of a PSM rotor, manufacturing and service costs can be reduced, since high-temperature-resistant and thus expensive magnets can be dispensed with.In the case of other topologies (e.g., SSM, ASM, SRM, AFM), this efficient cooling also leads to an increase in performance or continuous power, since the electric machine can be supplied with higher currents. The resulting increased heating of the rotor assembly and stator can be cooled more efficiently and effectively using the disclosed rotor assembly design.

[0019] Possible further developments of the device described above are explained in detail below.

[0020] The disc-shaped heat sink can be thermally conductive. The disc-shaped heat sink can optionally be electrically insulating. This prevents potential electrical short circuits between rotating and static components of the electrical machine, which could lead to malfunctions, failures, or damage. Furthermore, the heat generated during operation of the rotor assembly can be efficiently dissipated.

[0021] The disc-shaped heat sink can be designed as a single piece or in multiple pieces. The single-piece design of the disc-shaped heat sink can be manufactured from a single piece, which can simplify production, for example, through 3D sintering. A single-piece disc-shaped insulation body can also be less susceptible to potential weak points. A multi-piece disc-shaped heat sink can offer advantages in terms of customization and flexibility. By using multiple parts, the disc-shaped heat sink can take on more complex shapes or meet more specific requirements. In the multi-piece design of the disc-shaped heat sink, the interfaces of the individual parts can be connected (e.g., glued) and sealed (using a sealing compound) accordingly.

[0022] It can be provided that the radially arranged coolant outlet openings of the hollow rotor shaft extend over the circumference of the hollow rotor shaft and that the disc-shaped heat sink has corresponding coolant inlet openings in the same number and positioning as the coolant outlet openings of the hollow rotor shaft, and the coolant inlet openings are connected to the coolant passageways of the disc-shaped heat sink. The coolant can flow through the interior of the hollow rotor shaft to the coolant outlet openings and there enter the disc-shaped heat sink via the coolant inlet openings. The coolant can thus reach the disc-shaped heat sink via the coolant inlet openings, where it can be distributed according to the design of the disc-shaped heat sink. For example, eight coolant outlet openings can be provided, evenly distributed over the circumference of the hollow rotor shaft.Accordingly, the disc-shaped heat sink can, for example, have eight coolant inlet openings with the same arrangement. This allows the coolant to flow from the hollow rotor shaft to the outer circumference of the disc-shaped heat sink. Precise positioning of the coolant outlet openings of the disc-shaped heat sink over the coolant outlet openings of the hollow rotor shaft can be achieved using a suitable joining tool.

[0023] It can be provided that the coolant passages of the disc-shaped heat sink are designed to extend radially outward and have a corresponding number of openings on both sides for connecting to the coolant passages of the rotor cores. The coolant can flow (or be transported) outward in a star shape via the coolant passages and be evenly distributed between the axially extending coolant passages on both sides of the rotor cores. The coolant can reach both rotor cores (or sub-cores) via these axial coolant passages.

[0024] The coolant passages can be provided along the extension direction and at thermally stressed positions of the rotor cores. The thermally stressed positions of the rotor cores can refer to the areas or locations within the rotor cores where high thermal loads occur due to the heat generated during operation. These locations can be susceptible to elevated temperatures and impair the efficiency, performance, and service life of the electric machine if adequate cooling is not provided. This allows for more efficient heat dissipation.

[0025] It can be provided that the outlet openings of the first and second support disks are designed as axial outlet openings and / or radial outlet openings. Efficient and enhanced cooling of the outer regions of the stator winding heads can be achieved via the axial outlet openings. Efficient and enhanced cooling of the inner regions of the stator winding heads can be achieved via the radial outlet openings.

[0026] It can be provided that the disc-shaped heat sink and / or the radially extending insulation body comprise (or consist of) PEEK, PEI, PI, PTFE, PPS, LCP. In other words, the disc-shaped insulation body and / or the radially extending insulation body can be made of a material selected from the group comprising: PEEK, PEI, PI, PTFE, PPS, LCP. PEEK stands for polyetheretherketone and is a high-performance polymer with good mechanical, thermal, and chemical properties. PEI stands for polyetherimide and has high temperature resistance, mechanical strength, and electrical insulation properties. PI stands for polyimide and is a temperature-resistant polymer with good electrical insulation and mechanical strength. PTFE stands for polytetrafluoroethylene and offers good non-stick properties, electrical insulation, and thermal stability.PPS stands for polyphenylene sulfide and is a high-performance polymer with high temperature resistance, chemical resistance, and insulation properties. LCP stands for liquid crystal polymer and is a polymer with a crystalline structure, offering a combination of high temperature resistance, low moisture absorption, and electrical insulation. It can achieve the necessary electrical insulation with good temperature resistance and thermal conductivity.

[0027] The above description can be summarized in other words and in a possible more concrete embodiment of the disclosure as described below, whereby the following description is not to be interpreted as limiting the disclosure.

[0028] The rotor assembly described herein can have a rotor shaft, a disk-shaped heat sink, two rotor laminated cores (or sub-cores), and two support and balancing disks (optionally identical for the A and B sides of the rotor assembly). The rotor shaft can be designed as a hollow shaft and have radial bores. The cooling medium can thus flow through the interior of the rotor shaft to the radial bores and there into the disk-shaped heat sink. The disk-shaped heat sink can have (or consist of) an electrically insulating but thermally conductive material (e.g., PEEK) and can be designed either in one piece (e.g., by means of 3D sintering) or in several parts (e.g., from two half-shells). In the case of a multi-part heat sink, the interfaces can be connected (e.g., glued) and sealed (e.g., with sealing compound) accordingly.The cooling medium can enter the heat sink via radial bores, can then be transported radially outwards in a star shape through its main channels and distributed evenly between the axially running outlet channels on both sides. The cooling medium can reach both rotor laminations via these axial outlet channels. In these rotor laminations, the position of the axially running cooling channels can be selected so that they run as close as possible to the rotor hotspots. In the design described here, the rotor can be a PSM rotor. The hotspots can be the electrical machine used in the electric motor. The coolant can reach the support and balancing disks on both sides (A and B sides) via these axially running cooling channels.From there, it can be thrown off directly via radial and axial holes and channels onto the stator winding heads (stator hotspots) or other components of the electrical machine, which are thus also cooled efficiently. This concept enables particularly effective and direct cooling of the hotspots of the rotor and stator, as the disc-shaped heat sink and the holes and channels are provided in the rotor lamination and the adjoining components, in particular the stator winding heads. All holes and channels can be positioned in such a way that they do not adversely affect the electromagnetic design or other technical disciplines of design and layout, such as CAD, FEM or assembly. Efficient cooling can, on the one hand, improve performance and, on the other hand, reduce the risk of electric shock.Secondly, the continuous power of the drive can be improved and, secondly, in the case of a PSM rotor, costs can be saved because high-temperature-capable and resistant, and thus expensive, magnets can be dispensed with. In the case of other topologies (e.g. SSM, ASM, SRM, AFM), this efficient cooling can also lead to an increase in performance / continuous power because the electric machine can be supplied with higher currents; the resulting greater heating of the rotor assembly and stator can be cooled by the rotor assembly. The assembly concept deviates only slightly from standard assembly in the sense that a disc-shaped heat sink is inserted between two rotor laminated cores (sub-cores).When joining the heat sink to the rotor shaft, the two rotor lamination stacks (sub-packages) to the rotor shaft, and the two support and balancing disks, precise angular positioning is essential to ensure that the radial and axial bores and channels are aligned. This can be achieved using a joining tool.

[0029] Furthermore, an electric machine with a stator arrangement and a rotor arrangement according to the disclosure is provided. The above description with reference to the rotor arrangement also applies analogously to the electric machine, and vice versa.

[0030] The electric machine can be designed as an electric traction motor and can include permanent magnet motors, asynchronous motors, and / or brushless DC motors. The electric machine can serve as the primary and / or secondary drive for a motor vehicle. The electric machine can therefore be installed in the motor vehicle either individually or in combination with another drive machine, e.g., an internal combustion engine and / or a hydrogen drive.

[0031] Furthermore, a motor vehicle with the electric machine described above is provided. The above description with regard to the rotor arrangement and the electric machine applies analogously to the motor vehicle, and vice versa. The motor vehicle can be a passenger car, in particular an automobile, or a commercial vehicle, such as a truck.

[0032] Furthermore, a method for producing a rotor arrangement for an electric machine of a motor vehicle is provided. The method comprises providing a hollow rotor shaft which is arranged axially and extends at least over the length of the rotor arrangement and has radially arranged coolant outlet openings; providing at least two rotor laminations and a disc-shaped heat sink arranged between the at least two rotor laminations, wherein coolant passage channels are formed in the rotor laminations and in the disc-shaped heat sink; providing a first support disk and a second support disk which are arranged on a respective end face of the rotor arrangement and enclose the at least two rotor laminations, wherein the first support disk and the second support disk have outlet openings.The method comprises assembling the rotor arrangement so that the disc-shaped heat sink is arranged over the radially arranged coolant outlet openings of the hollow rotor shaft such that a coolant coming from the hollow rotor shaft flows via the coolant passage channels of the disc-shaped heat sink and the rotor laminated cores in the direction of the outlet openings of the first and second support discs and exits.

[0033] What has been described above with reference to the rotor arrangement, the electric machine and the motor vehicle also applies analogously to the method and vice versa.

[0034] Below is an optional embodiment with reference to the Fig. 1 and Fig. 7 described. Fig. 1 schematically shows a motor vehicle with an electric machine according to the disclosure; Fig. 2 shows schematically the rotor arrangement according to the disclosure, which is part of the Fig. 1 shown electrical machine; Fig. 3 shows schematically a hollow rotor shaft of the Fig. 2 shown rotor arrangement according to the disclosure; Fig. 4 shows schematically a disc-shaped heat sink in Fig. 2 shown rotor arrangement according to the disclosure; Fig. 5 shows schematically a rotor core of the Fig. 2 shown rotor arrangement according to the disclosure; Fig. 6 shows a schematic cross-sectional view of the rotor core of the Fig. 5 shown rotor lamination stack according to the disclosure, and Fig. 7 shows schematically a first and second support disc with hidden heat sink and rotor lamination packs of the Fig. 2 shown rotor arrangement according to the disclosure.

[0035] The Fig. 1, the motor vehicle 1 shown only schematically has the disclosed electric machine 3 for driving the motor vehicle 1. In the Fig. 1, only one electric machine 3 is shown, which does not preclude the possibility of a separate electric machine 3 being provided to drive the front axle and / or rear axle. Furthermore, a separate electric machine 3 can be provided to drive each wheel of the motor vehicle 1.

[0036] In Fig. 2 is the rotor arrangement 2 according to the disclosure of the Fig. 1, the electrical machine 3 is shown in perspective. The rotor assembly 2 has a hollow rotor shaft 7, which is arranged axially and extends at least over the length of the rotor assembly 2. A coolant can flow in the axial direction through the hollow configuration of the rotor hollow shaft 7.

[0037] Furthermore, the rotor assembly 2 has at least two rotor lamination stacks 8 and a disk-shaped heat sink 5 arranged between the at least two rotor lamination stacks 8. The at least two rotor lamination stacks 8 are enclosed by the first support disk 4 and the second support disk 6 arranged on the end faces 16 of the rotor assembly 2. The first and second support disks 4, 6 are structurally identical and have outlet openings 9, 11. The rotor assembly 2 can be a PSM rotor assembly.

[0038] In Fig. 3 shows the hollow rotor shaft 7 in perspective and in isolation. The hollow rotor shaft 7, in turn, has radially arranged coolant outlet openings 12. The coolant flows through the interior of the hollow rotor shaft 7 to the coolant outlet openings 12, exiting there radially and flowing radially into the disc-shaped heat sink 5. Eight coolant outlet openings can be provided, evenly distributed around the circumference of the hollow rotor shaft 7.

[0039] In Fig. 4, the disc-shaped heat sink 5 of the rotor assembly 2 according to the disclosure is shown schematically in isolation. The disc-shaped heat sink 5 is in the illustrated embodiment of the Fig. 4 is constructed in one piece. Alternatively, the disc-shaped heat sink 5 can be constructed in multiple parts. The disc-shaped heat sink 5 can be electrically insulating and thermally conductive. A material selected from the group consisting of PEEK, PEI, PI, PTFE, PPS, and LCP can be used for its manufacture.

[0040] The disc-shaped heat sink 5 has coolant inlet openings 13. The same number of coolant inlet openings 13 and the same positioning (equal distances from each other around the circumference) to the coolant outlet openings 12 of the hollow rotor shaft 7 (see also Fig. 3). The coolant inlet openings 13 are connected to coolant passage channels 14 of the disc-shaped heat sink 5. The disc-shaped heat sink 5 has, in the illustrated embodiment, the Fig. 4 has eight coolant inlet openings 13 for the radial entry of the coolant from the hollow rotor shaft 7.

[0041] The disc-shaped heat sink 5 also has the coolant passage channels 14, which extend radially outward from the coolant inlet openings 13. Each of the eight coolant passage channels 14 of the disc-shaped heat sink 5 in the illustrated embodiment of the Fig. 4 has three openings 15. The openings 15 are formed on both sides of the disc-shaped heat sink 5. The coolant can flow through the openings 15 in equal amounts into the rotor cores 8 in the axial direction toward the first support disc 4 and the second support disc 6. The disc-shaped heat sink 5 has a central opening 18 for accommodating the hollow rotor shaft 7. The central opening 18 is formed as an oversize.

[0042] In Fig. 5, the rotor lamination stack 8 of the rotor assembly 2 according to the disclosure is shown schematically in isolation. The at least two rotor lamination stacks 8 of the rotor assembly 2 are structurally identical, so that only one of the two rotor lamination stacks 8 is described in detail, whereby this description applies analogously to the other of the two rotor lamination stacks 8. The rotor lamination stack 8 has the coolant passages 10 running in the axial direction. The coolant passages 10 are formed at thermally stressed positions of the rotor lamination stacks 8. The thermally stressed positions can be magnets 17 of the rotor assembly. The coolant flows into the first and second support disks 4, 6 via the coolant passages 10. The rotor lamination stack has a central opening 19 for receiving the hollow rotor shaft 7. The central opening 19 is formed as an oversize. In Fig. 6 is a schematic cross-sectional view of the rotor core 8. In the Fig. Figure 6 shows the axially extending coolant passages 10 that extend through the rotor core 8. The coolant passages 10 run along the joined magnets 17.

[0043] In Fig.Figure 7 schematically shows the first support disk 4 and the second support disk 6 with the heat sink 5 and rotor cores 8 hidden away of the rotor arrangement 2 according to the disclosure. The first and second support disks 4, 6 close off the rotor arrangement 2 at the end faces 16 of the rotor arrangement 2. The first and second support disks 4, 6 are structurally identical. The coolant flows axially from the coolant passages 10 of the rotor cores 8 into the first and second support disks 4, 6. The first and second support disks 4, 6 have outlet openings 9, 11. The outlet openings 9, 11 are designed as axial outlet openings 9 and radial outlet openings 11. The outer regions of the stator winding heads can also be cooled via the axial outlet openings 9. The radial outlet openings can be used to cool the inner areas of the stator winding heads.The first and second support discs 4, 6 have a central opening 20 for receiving the hollow rotor shaft 7. The central opening 20 is designed as an oversize. The first and second support discs 4, 6 have a groove 21 (alternatively: chamfer), which can be used as a positioning aid for the drill for balancing holes. List of reference symbols 1 motor vehicle 2 Rotor arrangement 3 electric machine 4 first support disc 5 disc-shaped heat sink 6 second support disc 7 Rotor hollow shaft 8 rotor laminations 9 axial outlet opening 10 coolant passage rotor lamination packages 11 radial outlet opening 12 coolant outlet openings rotor hollow shaft 13 Coolant inlet openings heat sink 14 Coolant passage heat sink 15 openings 16 Front side of the rotor assembly 17 magnets 18 centric opening in the disc-shaped heat sink 19 centric opening in the rotor core 20 centric opening in the support discs 21 grooves 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 2019 / 026 7859 A1

[0005] JP 2019-170150 A

[0006] WO 2020 / 174 176 A1

[0007]

Claims

[1] Rotor arrangement (2) for an electric machine (3) of a motor vehicle (1), the rotor arrangement (2) comprising: - a hollow rotor shaft (7) which extends axially at least over the length of the rotor arrangement (2) and has radially arranged coolant outlet openings (12); - at least two rotor lamination stacks (8) and a disc-shaped heat sink (5) arranged between the at least two rotor lamination stacks (8), wherein coolant passage channels (10, 14) are formed in the rotor lamination stacks (8) and in the disc-shaped heat sink (5); - a first support disc (4) and a second support disc (6) which are arranged on a respective end face (16) of the rotor arrangement (2) and which enclose at least two rotor lamination stacks (8), wherein the first support disc (4) and the second support disc (6) have outlet openings (9, 11), characterized by , that - the disc-shaped heat sink (5) is arranged above the radially arranged coolant outlet openings (12) of the hollow rotor shaft (7) in such a way that a coolant coming from the hollow rotor shaft (7) flows via the coolant passage channels (10, 14) of the disc-shaped heat sink (5) and the rotor laminated cores (8) in the direction of the outlet openings (9, 11) of the first and second support discs (4, 6) and exits. [2] Rotor arrangement (2) according to claim 1, characterized by that the disc-shaped heat sink (5) is thermally conductive. [3] Rotor arrangement (2) according to claim 1 or 2, characterized by that the disc-shaped heat sink (5) is formed in one part or in several parts. [4] Rotor arrangement (2) according to at least one of the preceding claims, characterized by , that: - the radially arranged coolant outlet openings (12) of the hollow rotor shaft (7) extend over the circumference of the hollow rotor shaft (7), - the disc-shaped heat sink (5) has corresponding coolant inlet openings (13) in the same number and position as the coolant outlet openings (12) of the hollow rotor shaft (7), and - the coolant inlet openings (13) are connected to the coolant passage channels (14) of the disc-shaped heat sink (5). [5] Rotor arrangement (2) according to at least one of the preceding claims, characterized by that the coolant passage channels (14) of the disc-shaped heat sink (5) are designed to run radially outwards and have a corresponding number of openings (15) on both sides for connecting to the coolant passage channels (10) of the rotor laminated cores (8). [6] Rotor arrangement (2) according to at least one of the preceding claims, characterized by that the coolant passage channels (10) are formed along the direction of extension and at thermally stressed positions of the rotor laminated cores (8). [7] Rotor arrangement (2) according to at least one of the preceding claims, characterized by that the outlet openings (9, 11) of the first and second support discs (4, 6) are designed as axial outlet openings (9) and / or radial outlet openings (11). [8] Electric machine (3), characterized by that the electrical machine (3) comprises a stator arrangement and a rotor arrangement (2) according to at least one of the preceding claims. [9] Motor vehicle (1), characterized by that the motor vehicle (1) comprises the electric machine (3) according to claim 8. [10] Method for producing a rotor arrangement (2) for an electric machine (3) of a motor vehicle (1), comprising: - Provide: - a hollow rotor shaft (7) which extends axially at least over the length of the rotor arrangement (2) and has radially arranged coolant outlet openings (12); - at least two rotor lamination stacks (8) and a disc-shaped heat sink (5) arranged between the at least two rotor lamination stacks (8), wherein coolant passage channels (10, 14) are formed in the rotor lamination stacks (8) and in the disc-shaped heat sink (5); - a first support disc (4) and a second support disc (6) which are arranged on a respective end face (16) of the rotor arrangement (2) and which enclose at least two rotor lamination stacks (8), wherein the first support disc (4) and the second support disc (6) have outlet openings (9, 11), and - Assembling the rotor arrangement (2) so that the disc-shaped heat sink (5) is arranged above the radially arranged coolant outlet openings (12) of the hollow rotor shaft (7) in such a way that a coolant coming from the hollow rotor shaft (7) flows via the coolant passage channels (10, 14) of the disc-shaped heat sink (5) and the rotor laminated cores (8) in the direction of the outlet openings (9, 11) of the first and second support discs (4, 6) and exits.

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