Rotor for an electric machine

Abstract

The invention relates to a rotor (110) for an electric machine, wherein the rotor (110) has an axially extending rotor shaft (111), wherein the rotor shaft (111) has a first shaft (210) and a second shaft (220), wherein the second shaft (220) is arranged at least partially inside the first shaft (210), wherein at least a first axial end (221) of the second shaft (220) is arranged inside the first shaft (210), wherein the first shaft (210) has a coolant primary channel (225) and a coolant secondary channel (215) in a first axial end (211), wherein the second shaft (220) has at least one coolant channel (250) in a radially outer surface, and wherein the rotor (110) has a coolant distribution element (230) which is located inside the first shaft (210) between the first axial end (221) of the second shaft. (220) and the first axial end (211) of the first shaft (210),wherein a first end (251) of the at least one coolant channel (250) is in fluid communication with the coolant primary channel (225) by means of the coolant distribution element (230) and wherein a second end (252) of the at least one coolant channel (250) is in fluid communication with the coolant secondary channel (215) by means of the coolant distribution element (230).

Description

[0001] The present invention relates to a rotor for an electric machine and to an electric machine with such a rotor. Background of the invention

[0002] Electric machines with a rotor and a surrounding stator can be used in a variety of technical fields, for example in the automotive sector as motors and / or generators. Since a rotor can often be exposed to high temperatures during operation, cooling of the rotor may be desirable. For example, if a maximum permissible temperature is exceeded, the magnetization of permanent magnets used in the rotor can be reduced or even lost, making effective cooling of the rotor crucial. For this purpose, the rotor can be cooled, for example, by means of a coolant, such as oil, which can be supplied and removed via a rotor shaft. Disclosure of the invention

[0003] According to the invention, a rotor for an electric machine and an electric machine with such a rotor, comprising the features of the independent claims, are proposed. Advantageous embodiments are the subject of the dependent claims and the following description.

[0004] The rotor has an axially extending rotor shaft. The rotor shaft can be rotatably mounted in a housing of the electric machine. Furthermore, the rotor can have a rotor body that at least partially or at least sectionally surrounds the rotor shaft. The rotor body can include electromagnetically acting components of the rotor, e.g., permanent magnets. Additionally, a balancing disk can be provided at one or both axial ends of the rotor body. In the electric machine, the rotor body can be surrounded by a stator.

[0005] The rotor body and the stator can conveniently be arranged in a housing of the electric machine.

[0006] The rotor shaft comprises a first, outer shaft and a second, inner shaft. The first shaft is, in particular, designed as a hollow shaft. The second shaft is arranged at least partially or at least sectionally within the first shaft, with at least one first axial end of the second shaft being located within the first shaft. In particular, the first and second shafts are arranged coaxially with each other and are, furthermore, in particular, rotationally fixed or coupled to each other. The rotor body is advantageously arranged on the first, outer shaft or on a radially outer surface of the first shaft and is fixed there in a rotationally fixed manner, for example, by an interference fit.

[0007] The first shaft and the second shaft each have a first axial end and a second axial end. Without loss of generality, the first axial end of the first shaft and the second shaft can, for example, be an A-side or drive-side end of the respective shaft. Similarly, without loss of generality, the second axial end of the first shaft and the second shaft can, for example, be a B-side end of the respective shaft. For example, the second axial end of the first shaft can have an opening through which the second shaft can be inserted into the first shaft. The first axial end of the first shaft can, for example, protrude from the rotor body in the axial direction and be rotatably mounted in a bearing of the electric machine.Accordingly, for example, the second axial end of the second shaft can protrude from the first shaft and the rotor body when viewed in the axial direction, and in particular can also be rotatably mounted in a bearing of the electric machine.

[0008] The first shaft has a primary coolant channel and a secondary coolant channel at its first axial end. These primary and secondary coolant channels can each be located, for example, inside the first axial end of the first shaft. The primary coolant channel can be connected, for example, to a coolant supply located inside or outside the electrical machine. Similarly, the secondary coolant channel can be connected to a coolant outlet, which can also be located inside or outside the electrical machine.

[0009] Although embodiments of the invention are primarily described with the coolant primary channel functioning as a coolant supply and the coolant secondary channel functioning as a coolant discharge, the invention is not limited to this, but can of course also be used in reverse, with the coolant primary channel serving for coolant discharge and the coolant secondary channel serving for coolant supply.

[0010] The second shaft has at least one coolant channel on an outer surface, viewed in a radial direction. This outer surface is advantageously oriented towards the first shaft or an inner surface of the first shaft.

[0011] The rotor further comprises a coolant distribution element arranged within the first shaft between the first axial end of the second shaft and the corresponding first axial end of the first shaft. In particular, this coolant distribution element can be arranged between the first axial end of the second shaft and a radial inner surface or an inner radial face of the second shaft. The coolant distribution element is, in particular, arranged coaxially with the first shaft and the second shaft. In particular, the first shaft, the second shaft, and the distribution element are connected or coupled to each other in a rotationally fixed manner.

[0012] A first end of the at least one coolant channel is in fluid communication with the coolant primary channel in the first axial end of the first shaft via the coolant distribution element. A second end of the at least one coolant channel is in fluid communication with the coolant secondary channel in the first axial end of the first shaft via the coolant distribution element.

[0013] A coolant or cooling fluid, e.g., oil, can be supplied (or discharged) via the primary coolant channel to cool the rotor, particularly the rotor body. The coolant distribution element is advantageously designed to distribute the coolant supplied via the primary coolant channel into the coolant channels on the surface of the second shaft (or vice versa). Within the coolant channels, the coolant can flow over the surface of the second shaft. In doing so, the coolant can absorb heat transferred from the rotor body to the coolant via the first shaft. Once this cooling effect is achieved, the heated coolant can be discharged via the secondary coolant channel (or vice versa). For this purpose, the coolant distribution element is also specifically designed to direct heated coolant from the coolant channels into the secondary coolant channel.

[0014] The invention thus provides a cooled, in particular an oil-cooled, rotor, wherein the cooling is effected by means of separate elements in the rotor shaft, particularly advantageously by means of the coolant distribution element and the coolant channels. In particular, the coolant distribution element and the coolant channels enable effective distribution and flow of the coolant between the primary coolant channel and the secondary coolant channel to achieve a particularly effective cooling effect. Specifically, the coolant distribution element allows the coolant to be distributed to the individual coolant channels in a particularly effective and structurally simple manner. The coolant channels enable the cooling fluid to be guided particularly effectively over the surface of the secondary shaft to achieve the best possible cooling effect. The coolant distribution element can be adapted to the available space and dimensions within the rotor shaft in a particularly flexible and structurally simple way.

[0015] Conventionally, rotor cooling is usually achieved without an additional coolant distribution element, with coolant being supplied and discharged via the rotor shaft. Both coolant flow and torque transmission are typically accomplished via the rotor shaft, and thus by means of the same component. In contrast, the invention allows the functions of torque transmission and coolant flow to be separated and implemented by separate elements of the rotor. Torque transmission can be advantageously achieved via the first shaft. The coolant flow functions can be advantageously performed by means of the coolant distribution element and the coolant channels. In particular, this allows for a particularly effective and flexible cooling of the rotor.

[0016] The invention thus makes it particularly advantageous to effectively cool the rotor, especially the rotor body, during operation of the electric machine. Particularly advantageous is the effective cooling of permanent magnets used in the rotor, ensuring that their temperature does not exceed a maximum permissible value. In particular, this prevents the magnetization of the permanent magnets from being reduced or lost.

[0017] According to one embodiment, at least one coolant channel runs between the first end and the second end according to a predetermined pattern on the outer surface of the second shaft. This pattern is specified for each coolant channel in such a way that the coolant can be effectively guided across the surface of the second shaft in the respective channel and thereby effectively absorb heat from the rotor. Particularly advantageously, the at least one coolant channel, according to the respective pattern, runs at least once from the first axial end of the second shaft towards the second axial end of the second shaft and at least once back from the second axial end towards the first axial end. For example, the at least one coolant channel according to the respective pattern can have a meandering, curved, looped, or looped shape.

[0018] According to one embodiment, at least one coolant channel has a first section and a second section between the first end and the second end, wherein the first section extends from the first axial end of the second shaft towards the second axial end of the second shaft, in particular at least partially or at least sectionally in the axial direction. The second section extends back towards the first axial end, in particular at least partially or at least sectionally in the axial direction. Advantageously, these first and second sections of the respective coolant channel run parallel to each other. The coolant can be advantageously directed in the coolant channel, starting from the coolant distribution element, first towards the opposite axial end of the second shaft and from there back to the coolant distribution element.

[0019] According to one embodiment, the at least one coolant channel further comprises a third section, wherein the third section connects the first section to the second section. In particular, this third section extends at least partially or at least sectionally in the circumferential direction of the outer surface of the second shaft.

[0020] According to one embodiment, the at least one coolant channel is designed as a recess, groove, or channel in the outer surface of the second shaft. The first shaft and the second shaft can be sealed against each other, particularly in a fluid-tight manner. The coolant channel can advantageously be sealed by the inner surface of the first shaft facing the outer surface of the second shaft.

[0021] According to one embodiment, the coolant distribution element is manufactured in one piece or monolithically. It can be made of a metal, in particular aluminum or steel.

[0022] According to one embodiment, the coolant distribution element is designed as a disk or at least as a disk-like or disk-shaped element. This disk is, in particular, arranged coaxially to the first and second shafts and is rotationally fixed to or coupled to both shafts. In particular, the radius of the disk can correspond to the radius of the second shaft. Advantageously, this disk has individual openings and / or channels to establish the individual fluid connections between the primary coolant channel, the coolant channels, and the secondary coolant channel.

[0023] According to one embodiment, the coolant distribution element, which is particularly designed as a disc, has at least one radial or at least partially or sectionally extending first fluid connection channel in a radial surface facing the second shaft for establishing the fluid connection between the first end of the at least one coolant channel and the primary coolant channel. These first fluid connection channels are each advantageously provided to be connected to the first end of the respective coolant channel in the outer surface of the second shaft and to the primary coolant channel. For example, these first fluid connection channels can each be formed as a recess in the corresponding radial surface of the coolant distribution element.

[0024] According to one embodiment, the coolant distribution element, which is particularly designed as a disk, has at least one axial or at least partially or sectionally extending second fluid connection channel for establishing the fluid connection between the second end of the at least one coolant channel and the coolant secondary channel. These second fluid connection channels are each provided on an outer surface, or outer face, of the coolant distribution element when viewed in the radial direction. This outer surface is advantageously oriented towards the first shaft or the inner surface of the first shaft. Each of these second fluid connection channels is advantageously provided for connection to the second end of a respective coolant channel. Furthermore, each second fluid connection channel can be connected to the coolant secondary channel.These second fluid connection channels can also each be provided, for example, as a recess in the outer surface of the coolant distribution element.

[0025] According to one embodiment, the coolant distribution element, which is particularly designed as a disc, further comprises at least one radial or at least partially or sectionally extending third fluid connection channel for establishing the fluid connection between the second end of the at least one coolant channel and the coolant secondary channel. This third fluid connection channel is located in a radial surface facing the first axial end of the first shaft or in a radial surface facing away from the second shaft. Each of these at least one radial third fluid connection channel connects to one of the axial second fluid connection channels. Furthermore, each of these third fluid connection channels is designed to be connected to the coolant secondary channel. Advantageously, the third fluid connection channels are also formed as recesses in the corresponding radial surface of the coolant distribution element.

[0026] According to one embodiment, the primary coolant channel and / or the secondary coolant channel are each configured as a bore or cavity within the first axial end of the first shaft. Such a bore can, in particular, extend axially within the first axial end of the first shaft. It is also conceivable that the primary coolant channel and / or the secondary coolant channel are each configured as a separate element arranged within the first axial end of the first shaft. For example, this element can be provided in an axially extending bore within the first axial end of the first shaft.

[0027] According to one embodiment, the first shaft is manufactured in one piece or monolithically. It can be made of a metal, particularly steel or aluminum. The first shaft can be made of steel, in particular. This ensures the stability of the rotor.

[0028] According to one embodiment, the second shaft is multi-part and has a bearing part at its second axial end and a channel part at its first axial end. The channel part has at least one coolant channel. The channel part can be made of a metal, particularly aluminum or steel. The channel part can be made of aluminum. This allows the channels to be manufactured easily. For example, the coolant channels can already be integrated into a tool for manufacturing the channel part, e.g., in a die during extrusion or in a casting mold. The geometry of the coolant channels can therefore be determined by the tooling.

[0029] The bearing element protrudes from the first shaft at its second axial end and is designed to close the cavity of the first shaft at this second axial end, or to seal it against coolant. For example, the bearing element can serve to seal the opening at the second axial end of the first shaft through which the second shaft is inserted into the first shaft. The bearing element can be configured to protrude axially from the first shaft and the rotor body and, in particular, to be rotatably mounted in a bearing of the electric machine. The bearing element can be made of a metal, especially steel or aluminum. The bearing element can be made of steel. This ensures the stability of the rotor.

[0030] In one embodiment, the bearing part is made of a different material than the channel part. In this embodiment, the bearing part is made of steel and the channel part of aluminum. This ensures stability on the one hand and simplifies manufacturing on the other.

[0031] The invention is suitable for a wide variety of technical applications. It is particularly well-suited for use in a (motor) vehicle, where the electric machine can advantageously be provided as a motor and / or a generator.

[0032] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawing.

[0033] The invention is schematically illustrated in the drawing using exemplary embodiments and is described below with reference to the drawing. Brief description of the drawings Fig. Figure 1 schematically shows an embodiment of an electrical machine according to the invention with an embodiment of a rotor according to the invention in a cross-sectional view. Fig. Figure 2 schematically shows an embodiment of a rotor according to the invention in a cross-sectional view. Fig. Figure 3 schematically shows elements of an embodiment of a rotor according to the invention in a side view. embodiment(s) of the invention

[0034] In the figures, identical reference symbols denote identical or equivalent elements.

[0035] In Fig. Figure 1 is an embodiment of an electrical machine according to the invention, shown schematically in a cross-sectional view and labelled 100.

[0036] The electric machine 100 has a rotor 110 with an axially extending rotor shaft 111 and a rotor body 112 that at least partially or at least sectionally surrounds the rotor shaft 111. The rotor shaft 111 and the rotor body 112 are rotationally fixed to each other. The rotor body 112 includes magnetically active components of the rotor 110, e.g., permanent magnets and / or a rotor winding.

[0037] The electric machine 100 further comprises a stator 120 surrounding the rotor 110. The stator 120 may, for example, have a stator winding and / or permanent magnets. The rotor 110 and the stator 120 are arranged within a housing 130 of the electric machine 100. The rotor shaft 111 is rotatably mounted in the housing 130 via bearings (not shown in detail).

[0038] The rotor 110 can be exposed to high temperatures during operation of the electric machine 100. To effectively cool the rotor 110, according to one embodiment of the invention, the rotor 110 is provided with fluid cooling, as described below with reference to the Fig. 2 and Fig. 3 will be explained.

[0039] Fig. Figure 2 shows the rotor 110 according to an embodiment of the invention in a schematic cross-sectional view. The rotor shaft 111 has a first, outer shaft 210 and a second, inner shaft 220. The first shaft 210 has a first axial end 211, in Fig. 2 a right end, and a second axial end 212, in Fig. 2 a left end. Accordingly, the second shaft 220 has a first axial end 221, in Fig. 2 a right end, and a second axial end 222, in Fig. 2 a left end, on. The first end can, for example, be on an A-side of the electric machine 100 and the second end on a B-side.

[0040] The first shaft 210 is designed as a hollow shaft. In this case, the first shaft 210 is manufactured in one piece or monolithically and is made, for example, of steel to provide the necessary stability and strength.

[0041] The second shaft 220 is arranged at least partially, or at least sectionally, within the first shaft 210. At least the first axial end 221 of the second shaft 220 is arranged within the first shaft 210. The second axial end 212 of the first shaft 210 has an opening through which the second shaft 220 is inserted into the first shaft 210. The second shaft 220 is formed in two parts and comprises a bearing part 223 and a channel part 224. For example, the bearing part 223 is made of steel to provide the necessary stability and strength, and the channel part 224 is made of aluminum for ease of machining.

[0042] The first shaft 210 and the second shaft 220 are arranged coaxially and connected to each other in a rotationally fixed manner. In particular, the bearing element 223 is inserted into the first shaft 210 in a rotationally fixed and coolant-tight manner, for example by shrink-fitting. The rotor body 112 is arranged on an outer surface of the first shaft 210 and connected to it in a rotationally fixed manner. A balancing disk 240 is arranged at each of the two axial ends of the rotor body 112.

[0043] A primary coolant channel 225 and a secondary coolant channel 215 are provided in the first axial end 211 of the first shaft 210. For example, the secondary coolant channel 215 can be provided as an axial bore within the first axial end 211 of the first shaft 210. The primary coolant channel 225 can, for example, be provided in a separate component, such as a tube, within the axial bore within the first axial end 211 of the first shaft 210. It is also conceivable that both the primary coolant channel 225 and the secondary coolant channel 215 are each provided as axial bores within the first axial end 211 of the first shaft 210.

[0044] The primary coolant channel 225 can be connected to a coolant supply located inside or outside the electric machine 100. The secondary coolant channel 215 can be connected to a coolant outlet located inside or outside the electric machine 100. The coolant flow through the electric machine is illustrated by a dashed bar 10. However, as explained above, the invention is not limited to the primary coolant channel acting as a coolant supply and the secondary coolant channel acting as a coolant outlet.

[0045] The second shaft 220, in particular the channel section 224, further comprises a plurality of coolant channels 250 on an outer surface viewed in the radial direction. This outer surface of the second shaft 220 faces, in particular, an inner surface of the first shaft 210. These coolant channels 250 are, in particular, each provided as recesses in the outer surface of the second shaft 220.

[0046] The rotor 110 further comprises a coolant distribution element 230, which is arranged within the first shaft 210 between the first axial end 221 of the second shaft 220 and the first axial end 211 of the first shaft 210. This coolant distribution element 230 is, for example, designed as a disk that is arranged coaxially with the first shaft 210 and the second shaft 220 and is rotationally fixed to these two shafts 210, 220. The radius of the disk-shaped coolant distribution element 230 corresponds (in particular approximately) to a radius of the second shaft 220. The coolant distribution element 230 can, in particular, also be made of aluminum to facilitate machining.

[0047] A first end 251 of each coolant channel 250 is in fluid communication with the coolant primary channel 225 in the first axial end 211 of the first shaft 210 by means of the coolant distribution element 230. Furthermore, a second end 252 of each coolant channel 250 is in fluid communication with the coolant secondary channel 215 in the first axial end 211 of the first shaft 210 by means of the coolant distribution element 230.

[0048] To establish this fluid connection between the respective first end 251 of the individual coolant channels 250 and the coolant primary channel 225, the coolant distribution element 230 has a plurality of radial or radially extending first fluid connection channels 231. These first fluid connection channels 231 are each provided as a recess in a radial surface of the coolant distribution element 230 facing the second shaft 220. Each of these first fluid connection channels 231 connects the respective first end 251 of one of the coolant channels 250 to the coolant primary channel 225.

[0049] To establish the fluid connection between the respective second end 252 of the individual coolant channels 250 and the coolant secondary channel 215, the coolant distribution element 230 has a plurality of axial second fluid connection channels 232 and a plurality of radial third fluid connection channels 233. These second fluid connection channels 232 are each provided as a recess in a radially outer surface of the coolant distribution element 230. The third fluid connection channels 233 are each provided as a recess in a radial surface of the coolant distribution element 230 facing the first axial end 211 of the first shaft 210. Every second fluid connection channel 232 is connected to the respective second end 252 of one of the coolant channels 250. Every third fluid connection channel 233 connects to one of the second fluid connection channels 232.Furthermore, every third fluid connection channel 233 is connected to the coolant secondary channel 215.

[0050] The individual coolant channels 250 can extend between their respective first and second ends 251, 252 in a predetermined pattern on the outer surface of the second shaft 220 or the channel section 224, in particular such that, viewed in the direction of coolant flow, each coolant channel 250 extends at least once from the first axial end 221 of the second shaft 220 towards the second axial end 222 of the second shaft 220 and at least once again from the second axial end 222 back towards the first axial end 221, as shown below by reference to Fig. 3 will be explained.

[0051] Fig. Figure 3 schematically shows the second shaft 220, including the bearing part 223 and the channel part 224, and the coolant distribution element 230 of the rotor 110 according to an embodiment of the invention in a side view. As in Fig.As can be seen in Figure 3, each of the coolant channels 250 can, for example, have a first section 310, a second section 320, and a third section 330 between its respective first end 251 and its respective second end 252. These first sections 310 each extend axially from the first axial end 221 of the second shaft 220 towards the second axial end 222 of the second shaft 220. The second sections 320 each extend axially back from the second axial end 222 to the first axial end 221. The third sections 330 each extend circumferentially and connect the respective first section 310 with the respective second section 320 of the respective coolant channel 250.

[0052] The invention thus provides a particularly advantageous fluid- or oil-cooled rotor 110, wherein the cooling is effected by means of separate elements in the rotor shaft 111, in particular by means of the coolant distribution element 230 and the channel section 224 or the coolant channels 250. These elements can, in particular, be made of a different material than the torque-bearing parts of the rotor shaft. The coolant distribution element 230 enables optimal distribution of fresh coolant from the interior of the second shaft 220 to the individual coolant channels 250 and easy transfer of heated coolant from the coolant channels 250 to the coolant outlet (or vice versa). By means of the coolant channels 250, the cooling fluid can be guided particularly effectively over the surface of the second shaft 220 to achieve optimal cooling of the rotor 110.The functions of torque transmission and coolant guidance can be separated and realized by separate elements of the rotor, whereby the torque transmission can be carried out by means of the first shaft 110 and the bearing part 223 and the coolant guidance by means of the coolant distribution element 230 and the channel part 224 or the coolant channels 250.

Claims

[1] Rotor (110) for an electric machine (100), wherein the rotor (110) has a rotor shaft (111) extending in an axial direction, wherein the rotor shaft (111) has a first shaft (210) and a second shaft (220), wherein the second shaft (220) is arranged at least partially inside the first shaft (210), wherein at least a first axial end (221) of the second shaft (220) is arranged inside the first shaft (210), wherein the first shaft (210) has a coolant primary channel (225) and a coolant secondary channel (215) at a first axial end (211) of the first shaft (210), wherein the second shaft (220) has at least one coolant channel (250) on an outer surface viewed in the radial direction, wherein the rotor (110) has a coolant distribution element (230) which is arranged inside the first shaft (210) between the first axial end (221) of the second shaft (220) and the first axial end (211) of the first shaft (210), wherein a first end (251) of the at least one coolant channel (250) is in fluid communication with the coolant primary channel (225) by means of the coolant distribution element (230) and wherein a second end (252) of the at least one coolant channel (250) is in fluid communication with the coolant secondary channel (215) by means of the coolant distribution element (230). [2] Rotor (110) according to claim 1, wherein the least one coolant channel (250) runs between the first end (251) of the at least one coolant channel (250) and the second end (252) of the at least one coolant channel (250) according to a predetermined pattern in the outer surface of the second shaft (220). [3] Rotor (110) according to claim 1 or 2, wherein the at least one coolant channel (250) between the first end (251) of the at least one coolant channel (250) and the second end (252) of the at least one coolant channel (250) has a first section (310) and a second section (320), wherein the first section (310) extends from the first axial end (221) of the second shaft (220) towards a second axial end (222) of the second shaft (220) and wherein the second section (320) extends back towards the first axial end (221) of the second shaft (220). [4] Rotor (110) according to claim 3, wherein the at least one coolant channel (250) further comprises a third section (330), wherein the third section (330) connects the first section (310) with the second section (320). [5] Rotor (110) according to one of the preceding claims, wherein the at least one coolant channel (250) is formed as a recess in the outer surface of the second shaft (220). [6] Rotor (110) according to one of the preceding claims, wherein the coolant distribution element (230) is designed as a disk. [7] Rotor (110) according to one of the preceding claims, wherein the coolant distribution element (230) for establishing the fluid connection between the first end (251) of the at least one coolant channel (250) and the coolant primary channel (225) has at least one radial first fluid connection channel (231) in a radial surface facing the second shaft (220). [8] Rotor (110) according to one of the preceding claims, wherein the coolant distribution element (230) for establishing the fluid connection between the second end (252) of the at least one coolant channel (250) and the coolant secondary channel (215) has at least one axial second fluid connection channel (232) in an outer surface viewed in a radial direction. [9] Rotor (110) according to claim 8, wherein the coolant distribution element (230) for establishing the fluid connection between the second end (252) of the at least one coolant channel (250) and the coolant secondary channel (215) further comprises at least one radial third fluid connection channel (233) adjoining the at least one axial second fluid connection channel (232) in a radial surface facing the first axial end (211) of the first shaft (210). [10] Rotor (110) according to one of the preceding claims, wherein the coolant primary channel (225) and / or the coolant secondary channel (215) is each formed as a bore within the first axial end (211) of the first shaft (210) and / or in a separate element arranged within the first axial end (211) of the first shaft (210). [11] Rotor (110) according to one of the preceding claims, wherein the first shaft (210) is formed in one piece or monolithically, in particular from steel. [12] Rotor (110) according to one of the preceding claims, wherein the second shaft (220) is formed in multiple parts and has a bearing part (223) at the first axial end (221) of the second shaft (220) and a channel part (224) at the second axial end (222) of the second shaft (220). [13] Rotor (110) according to claim 12, wherein the channel part (224) has the at least one coolant channel (250) and is in particular made of aluminium and / or wherein the bearing part (223) is connected to the first shaft (210) in a rotationally fixed manner and is in particular made of steel. [14] Rotor (110) according to claim 12 or 13, wherein the bearing part (223) is made of a different material than the channel part (224). [15] Electric machine (100) with a rotor (110) according to one of the preceding claims.

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