Rotor shaft with integrated cooling channels

Abstract

The present disclosure relates to a rotor shaft for a rotor of an electric machine. The rotor shaft comprises an outer sleeve, an inner sleeve arranged inside the outer sleeve and two coolant distribution elements each arranged on one end of the rotor shaft. The outer sleeve has an internal profile with a multiplicity of longitudinal grooves. As an alternative or in addition, the inner sleeve has an external profile with a multiplicity of longitudinal grooves. The internal profile of the outer sleeve and / or the external profile of the inner sleeve define a multiplicity of cooling channels through which a coolant is able to flow along the rotor shaft from one coolant distribution element to the other coolant distribution element. The present disclosure furthermore relates to a rotor of an electric machine comprising the disclosed rotor shaft and to an associated electric machine.

Description

[0001] Rotor shaft with integrated cooling channels

[0002] 1. Technical area

[0003] The present disclosure relates to a rotor shaft for electrical machines such as electric motors or generators with integrated cooling channels.

[0004] 2. State of the art

[0005] Rotor shafts of rotating electrical machines, such as electric motors or generators, heat up during use. The resulting heat can be transferred to the stator and / or rotor windings, for example. This can lead to undesirable material deformation and reduce the efficiency of the electrical machine. To prevent this, the heating can be counteracted through passive or active cooling. One example is air cooling, in which air is directed over and / or through the electrical machine. Another approach is active cooling of the rotor using a liquid cooling medium.

[0006] Different rotor shafts with active cooling are known from the state of the art.

[0007] For example, DE io 2019 207325 Ai describes a cooling arrangement for a heat-generating rotating component of an electrical machine: A rotatably mounted hollow shaft, which is connected in a rotationally fixed manner to the rotor shaft, has at least one cooling channel for cooling lubricant, wherein the at least one cooling channel comprises a hollow shaft channel, a supply channel and an outlet channel.

[0008] US 2020 / 0251963 Ai describes an electric machine comprising a one-piece hollow rotor shaft through which a liquid coolant can flow and in whose interior a plurality of heat dissipation fins are located. DE io 2016 202416 B4 discloses a rotor shaft arrangement for a rotor of an electric motor, which has a hollow shaft for receiving a rotor body and a heat sink arranged in the hollow shaft, which has radially extending cooling fins and is in radial thermal contact with the hollow shaft. The heat sink has an axially continuously open structure so that a cooling medium in the hollow shaft can flow axially through the heat sink, wherein the open structure is formed by defined channels.

[0009] DE 10 2017112348 Ai relates to an electric machine comprising a rotor rotatable relative to a stator, having at least one rotor shaft, and a channel system through which a coolant can flow for cooling the machine. The channel system extends at least partially within the rotor shaft. The channel system comprises a cooling channel that is conically shaped, at least partially, in the longitudinal direction of the rotor shaft, so that the coolant can be conveyed by a rotational movement of the rotor shaft in the direction of an increasing channel diameter.

[0010] Further from the state of the art known rotor waves are described in DE 11 2010 004773 T5, US 9,148,041 B2, EP 3384581 Bl, DE 10 2017112348 Al, DE 10 2010 2073, Al 3507889 Bl, DE 10 2019 108 943 Al, EP 3555 992 Bl, EP 3 598 611 Al, EP 3 961875 Al, US 7,579,725 B2, EP 1953 896 Bl, DE 2017 Al, 2356 US 9,33L552 B2, EP 3 303 039 Bl, EP 3 673 568 Bl, EP 3 501085 Bl, DE 10 2016 209 173 Ai, EP 3 152 819 Bi, DE 10 2016 2016 EP 3437 und Bl 919 Bi.

[0011] 3. Summary of Revelation

[0012] However, the rotor shafts known from the state of the art have several disadvantages. In particular, some of the rotor shafts known from the state of the art can only be manufactured with considerable labor, resulting in material wear, and consequently high costs. Furthermore, the cooling approaches known from the state of the art are often inadequate, especially for use in compact electric motors with high power density. Furthermore, some of the known rotor shaft cooling structures are complex, delicate, and / or have multiple designs, which can result in increased scrap in production and shorter product lifespans.

[0013] The present application is therefore based on the problem of at least partially mitigating some of the described disadvantages of the prior art. This problem is at least partially solved by the subject matter of the independent claim. Exemplary embodiments are described in the dependent claims. Unless otherwise stated, material properties are to be determined according to the relevant standards.

[0014] In one embodiment, the present disclosure provides a rotor shaft for a rotor of an electric machine. The rotor shaft comprises a casing tube, an inner tube arranged inside the casing tube, and two cooling medium distribution elements. The cooling medium distribution elements are each arranged at one end of the rotor shaft. The casing tube has an inner profile with a plurality of longitudinal grooves and / or the inner tube has an outer profile with a plurality of longitudinal grooves. Furthermore, the inner profile of the casing tube and / or the outer profile of the inner tube defines a plurality of cooling channels through which a cooling medium can flow from one of the cooling medium distribution elements along the rotor shaft to the other cooling medium distribution element.

[0015] The cooling medium distribution elements can, as described below, be designed as end plugs in some embodiments.

[0016] In a further exemplary embodiment, the rotor shaft comprises a casing tube having an inner profile with a plurality of longitudinal grooves, an inner tube arranged inside the casing tube, and first and second cooling medium distribution elements or first and second end plugs, each of which is connected to one end of the casing tube in a form-fitting and friction-fitting manner or a form-fitting and material-fitting manner by engaging in a portion of the plurality of longitudinal grooves; wherein the inner profile of the casing tube and the outer side of the inner tube define a plurality of cooling channels through which a cooling medium can flow along the casing tube. A form-fitting and friction-fitting or a form-fitting and material-fitting connection also includes a combined form-fitting, friction-fitting, and material-fitting connection in the context of this application.

[0017] The tube-in-tube design described above significantly simplifies the design and manufacture of an actively cooled rotor shaft while simultaneously improving cooling. Furthermore, the positive and frictional connection between the profiled casing tube and the cooling medium distribution elements / end plugs allows high torque transmission, while simultaneously defining the cooling channels along the longitudinal grooves of the casing tube's inner profile and / or the outer profile of the inner tube.

[0018] This simplification of the rotor shaft design offers several advantages: No additional element is required for torque transmission, resulting in material and weight savings. The dual function of the inner profile of the casing tube—on the one hand, defining the axially extending cooling channels and, on the other hand, providing positive and frictional engagement through toothing with the cooling medium distribution elements—allows the casing tube to be manufactured with minimal labor and separately from the other components of the rotor shaft.

[0019] The inner tube and casing tube can be cold-formed, e.g. drawn, metal tubes made from common materials such as E355 and 42CrMo4, structural steels, heat-treatable steels and / or case-hardening steels. The cooling medium distribution elements can be forged, additively manufactured or machined, for example. This allows the manufacturing process of the casing tube to be easily and inexpensively modified to produce casing tubes in modified designs for new rotor shafts, for example with different lengths, diameters, thicknesses and / or types and depths of profiling. In particular, one or both cooling medium distribution elements can be used directly for torque transmission thanks to the positive or non-positive connection to the casing tube or the inner profile of the casing tube, which significantly simplifies the design of the rotor shaft.To further save weight and manufacturing effort, the casing tube can have a taper at one end (or both ends) that is configured to receive one of the cooling medium distribution elements (or both) inside the casing tube and to function as a fit or bearing seat for a rotary bearing of the electric machine or to encompass such a fit or bearing seat (cf. Fig. 11 to Fig. 13B). In such embodiments, the cooling medium distribution element, which is arranged inside the taper, can be made of a low-weight material such as a plastic (e.g., PEEK). The inner tube can also be made of such a material.

[0020] Furthermore, at least one of the two cooling medium distribution elements of the rotor shaft can have a torque transmission element. This arrangement ensures that the production of the other components of the rotor shaft—i.e., the jacket tube, the inner tube, the other cooling medium distribution element, and, if applicable, a cooling medium guide tube—remains unaffected by the specific design of the torque transmission element.

[0021] To simplify the production of the casing tube—for example, through axial cold forming or cold drawing—and the connection to the cooling medium distribution elements, the inner profile of the casing tube can have periodically repeating elevations and depressions—for example, sinusoidal ones—along the circumference of the casing tube. This also allows the cooling medium to be evenly distributed for cooling purposes within the rotor shaft.

[0022] To easily achieve a positive connection between the inner tube and the casing tube to define the cooling channels, the inner tube can engage in some of the plurality of longitudinal grooves. This arrangement prevents any unintentional positioning and / or rotation of the inner tube and the casing tube relative to one another. Furthermore, the inner tube and outer tube can be connected in this arrangement in a material- and labor-saving manner. In addition, the cooling medium is thus evenly distributed over the rotor shaft to cool the rotor shaft. In other embodiments, one or both of the cooling medium distribution elements can be welded to the casing tube in a rotationally fixed manner without engaging the longitudinal grooves.

[0023] Furthermore, the inner tube can have a cross-section with periodically repeating elevations and depressions along its circumference, with the elevations of the inner tube engaging with some of the longitudinal grooves of the inner profile of the casing tube (see also Figs. 1A and 3B). The periodically repeating elevations of the inner tube, like the possible periodic profiling of the casing tube, enable a uniform distribution of the cooling medium for cooling the rotor shaft. Furthermore, such a periodic profiling of the inner tube and the casing tube can facilitate assembly, since the symmetry allows for several relative positions in which the two profiles interlock.

[0024] In one possible embodiment, the outer tube has a maximum wall thickness in the range of 2.00 mm to 10.00 mm and / or the inner tube has a wall thickness in the range of 0.5 mm to 5.00 mm. These thickness ranges allow, on the one hand, to ensure high structural stability for transmitting high torques and, on the other hand, to produce material-saving components. Within this thickness range, the same manufacturing process can be used for various embodiments, for example, but not exclusively, for tubes of different thicknesses, profiles, or lengths, with minor and cost-effective adjustments.

[0025] Furthermore, in one possible embodiment, the inner profile of the jacket tube can have a profile depth in the range of 1.00 mm to 6.00 mm, preferably in the range of 1.5 mm to 3.5 mm, and / or the inner tube can have a profile depth in the range of 0.5 mm to 4.00 mm, preferably in the range of 1.5 mm to 3.5 mm. Profile depths in these ranges are characterized by the fact that the flow behavior of the cooling medium with regard to laminar or turbulent dynamics can be advantageously adjusted according to the requirements of the respective system. In addition, such profile depths can ensure sufficient torsional strength for the cooling medium distribution elements in order to be able to transmit high torques. In particular, such profile depths can ensure that turbulence can develop despite a high mass flow of the cooling medium, which optimizes the cooling efficiency.

[0026] To improve the connection of the cooling medium distribution elements to the casing tube, in one possible embodiment, one or both of the cooling medium distribution elements can have an outer profile that engages with the inner profile of the casing tube and / or the cooling medium distribution elements can be pressed onto the casing tube. The interlocking of the outer profile of the cooling medium distribution elements with the inner profile of the casing tube utilizes an advantageous design of the positive connection by using the existing profiling of the casing tube to define the cooling channels. This type of positive connection saves material, as no additional fastening elements are required, and it also saves labor during production. Alternatively or additionally, the cooling medium distribution elements can also be welded to the casing tube.

[0027] In order to guide the cooling medium to the cooling channels defined by the inner tube and the jacket tube, in some embodiments the cooling medium distribution elements can each have a cooling medium distribution structure that is connected to one of the cooling channels defined by the inner profile of the jacket tube and the outer side of the inner tube. This eliminates the need for an additional cooling medium supply, which would complicate the design of the rotor shaft, and the manufacture of the jacket tube and the inner tube remains largely unaffected by the specific design of the cooling medium supply. In addition, the positioning of the cooling medium distribution structure in the cooling medium distribution elements enables various architectures for the cooling medium line through the rotor shaft (see Fig. 4A, Fig. 4B and Fig. 4C as well as Fig. 12A, Fig. 12B and Fig. 12C) and optionally through further elements attached to the rotor shaft (see Fig. 5A and Fig. 5B as well as Fig. 13A and Fig.13B), such as elements for electromagnetic power transmission, such as a rotor core with permanent magnets or with rotor windings.

[0028] For reasons of accessibility for inlet and outlet devices, depending on the arrangement of the rotor shaft, it may be advantageous for the cooling medium line if, in some embodiments, one of the cooling medium distribution elements has an inlet for the cooling medium that is connected to the cooling medium distribution structure and the other cooling medium distribution element has an outlet for the cooling medium that is connected to the cooling medium distribution structure (see Fig. 4B and Fig. 5B as well as Fig. 12A and Fig. 12B).

[0029] Alternatively, in other possible areas of application, it may also be advantageous if, in other embodiments, a cooling medium guide pipe is arranged within the inner pipe and connects the two cooling medium distribution elements to one another in such a way that the cooling medium can flow from one cooling medium distribution element to the other through the cooling medium guide pipe and one of the cooling medium distribution elements has an inlet and an outlet for the cooling medium, wherein the outlet is connected to the cooling medium distribution structure and the inlet to the cooling medium guide pipe (see Fig. 4A, Fig. 4C and Fig. 5A as well as Fig. 12A, Fig. 12C and Fig. 13A) or vice versa.

[0030] In one possible embodiment of the rotor shaft, the cooling medium distribution element, which has the inlet for the cooling medium, also includes the torque transmission element (see Fig. 4A, Fig. 5A, Fig. 12A, and Fig. 13A). This arrangement can be advantageously combined, for example, if the inlet for the cooling medium is located coaxially inside the torque transmission element. In general, the individual components can be arranged in a space- and material-saving manner.

[0031] In a further embodiment of the rotor shaft, the cooling medium distribution element, which comprises the torque transmission element, has no external inlets or outlets for the cooling medium (see Fig. 4C and Fig. 12C), which enables more compact drive systems.

[0032] The present application further relates to a rotor for an electrical machine, comprising a rotor shaft as described above and an element for electromagnetic force transmission, which is connected in a rotationally fixed, preferably non-positively, manner to a portion of the outer surface of the casing tube. Thus, the element for electromagnetic force transmission is located near the cooling channels in the casing tube, which can have a beneficial effect on the temperature in the element for electromagnetic force transmission. Furthermore, no additional support element is required to secure the element for electromagnetic force transmission. The element for electromagnetic force transmission can thus be cooled via the rotor cooling system, which improves the efficiency of the machine, particularly in non-permanently excited machines, such as asynchronous machines.

[0033] To improve the cooling of the electromagnetic power transmission element, it may be advantageous if the electromagnetic power transmission element also has at least one cooling channel connected to the cooling medium distribution structure of both cooling medium distribution elements (see Fig. 5A and Fig. 5B as well as Fig. 13A and 13B). This can counteract the heating of the entire rotor and achieve even higher efficiency.

[0034] The present application further relates to an electric machine comprising a stator and a rotor as described above.

[0035] 4. Brief description of the drawings

[0036] The drawings show:

[0037] Fig. 1A is a side view of the components of a rotor shaft according to an exemplary embodiment of the present disclosure;

[0038] Fig. 1B is a side view of the assembled rotor shaft of Fig. 1A;

[0039] Fig. 2A is a side view of a first end plug according to a possible embodiment of the present disclosure;

[0040] Fig. 2B is a side view of the first end plug of Fig. 2A;

[0041] Fig. 2C is a side view of a second end plug according to a possible embodiment of the present disclosure; IO

[0042] Fig. 2D is a side view of the second end plug of Fig. 2C;

[0043] Fig. 3A is a cross-sectional view of a rotor shaft according to a possible embodiment with a round inner tube without profiling;

[0044] Fig. 3ß a cross-sectional view of a rotor shaft according to a possible embodiment with a profiled inner tube, wherein the elevations of the profiling of the inner tube engage in some of the recesses of the inner profile of the casing tube;

[0045] Fig. 4A shows a longitudinal section through a rotor shaft according to an embodiment with an additional coolant guide tube;

[0046] Fig. 4B shows a longitudinal section through the rotor shaft according to an embodiment, without an additional coolant guide tube;

[0047] Fig. 4C shows a longitudinal section through a rotor shaft according to a further embodiment with an additional coolant guide tube;

[0048] Fig. 5A shows a longitudinal section of a rotor shaft with a coolant guide tube and additional cooling channels in an element for electromagnetic power transmission;

[0049] Fig. 5ß a longitudinal section of a rotor shaft without additional coolant guide tube and additional cooling channels in an element for electromagnetic power transmission;

[0050] Fig. 6 shows an electric machine according to a possible embodiment with a rotor as described herein and a stator;

[0051] Fig. 7A is a side view of the components of a rotor shaft according to an exemplary embodiment of the present disclosure with a press-fitted coolant distribution element / end plug, a tapered jacket tube, and a coolant distribution element arranged within the taper;

[0052] Fig. 7ß is a side view of the components of a rotor shaft according to an embodiment of the present disclosure with a welded coolant distribution element / end plug, a tapered jacket tube, and a coolant distribution element arranged within the taper;

[0053] Fig. 7C is a side view of the assembled rotor shaft of Fig. 7A or 7ß;

[0054] Fig. 8 is a side view of the first end plug of Fig. 7B;

[0055] Fig. 9A is a side view of a tapered jacket tube according to a

[0056] Design with an inner profile with helical longitudinal cracks;

[0057] Fig. 9ß an internal view of the tapered jacket tube of Fig. 9A;

[0058] Fig. 9C is a plan view of a jacket pipe according to an embodiment with an inner profile with helical longitudinal cracks;

[0059] Fig. 10A is a cross-sectional view of a rotor shaft according to a possible embodiment with a profiled inner tube having a cross-section with three-fold rotational symmetry, wherein the elevations of the profiling of the inner tube engage in some of the depressions of the inner profile of the jacket tube having a cross-section with three-fold rotational symmetry;

[0060] Fig. 10B is a cross-sectional view of a rotor shaft according to a possible embodiment with a hexagonal inner tube and an outer tube whose inner profile is configured to rest with its elevations against the outer side of the inner tube; Fig. 11 is a side view of the components of a rotor shaft according to an embodiment of the present disclosure with a pressed-in end plug, an inner tube with an outer profile, and a tapered outer tube without an inner profile;

[0061] Fig. 12A shows a longitudinal section through a rotor shaft according to an embodiment with a tapered jacket tube and additional coolant guide tube;

[0062] Fig. 12B shows a longitudinal section through the rotor shaft according to an embodiment with a tapered jacket tube and without an additional coolant guide tube;

[0063] Fig. 12C shows a longitudinal section through a rotor shaft according to a further embodiment with a tapered jacket tube and additional coolant guide tube;

[0064] Fig. 13A shows a longitudinal section of a rotor shaft with a tapered casing tube, a coolant guide tube and additional cooling channels in an element for electromagnetic power transmission;

[0065] Fig. 13B shows a longitudinal section of a rotor shaft with a tapered casing tube, without an additional coolant guide tube and additional cooling channels in an element for electromagnetic power transmission.

[0066] 5. Detailed description of some implementation examples

[0067] In the following, some exemplary embodiments of the present disclosure are described using some exemplary rotor shafts for electrical machines. Various feature combinations are described with reference to the illustrated embodiments. Naturally, not all features of the described embodiments need to be present to implement the present invention. Furthermore, the embodiments can be modified by combining certain features of one embodiment with one or more features of another embodiment—provided this is technically compatible and expedient—without deviating from the disclosure and scope of the present invention, which is defined by the claims.

[0068] Fig. 1A shows a side view of the components of a rotor shaft 1 according to a possible embodiment of the present disclosure. This comprises a casing tube 10, for example with a wall thickness in the range of 2.00 mm to 10.00 mm, with a periodic inner profile 11, which in the illustrated embodiment has a plurality of axially extending longitudinal grooves. The illustrated embodiment also comprises an inner tube 20, for example with a wall thickness of 0.5 mm to 5.00 mm, a first end plug or cooling medium distribution element 30, a second end plug or cooling medium distribution element 40, and a cooling medium guide tube 50. The first end plug 30 can have an outer profile 31 and the second end plug 40 can have an outer profile 41.In the illustrated embodiment, the second end plug 40 has a cooling medium distribution structure 42 for the inlet of the cooling medium, and the first end plug 30 has the cooling medium distribution structure 32, 33 for the outlet of the cooling medium. In the illustrated embodiment, the first end plug 30 further has a torque transmission element 34, via which the rotor shaft 1 can be connected, for example, to a wheel to be driven, propeller, gearbox, or the like. Other corresponding embodiments can, for example, comprise other inner profiles 11 of the casing tube 10 and outer profiles 31, 41 of the end plugs 30, 40, other cooling medium distribution structures 32, 33, 42, and / or other torque transmission elements 34, and / or can dispense with the use of a cooling medium guide tube 50.

[0069] Fig. 1B shows a side view of the rotor shaft 1 according to a possible embodiment, assembled from the components described in Fig. 1A, in which the casing tube 10 is positively and non-positively connected to the first end plug 30 and the second end plug 40, wherein the first end plug 30 can have a torque transmission element 34. The connection between the casing tube 10 and the end plugs 30, 40 can be made, for example, by pressing the end plugs 30, 40 onto the casing tube 10, wherein the first end plug 30 and the second end plug 40 each engage in a part of the plurality of longitudinal grooves of the inner profile 11 of the casing tube 10, for example so that the elevations of the outer profiles 31, 41 engage in the inner profile 11.The inner tube 20 and the cooling medium guide tube 50 are located, not visible in this view, coaxial with the jacket tube 10 inside the jacket tube 10 and at least partially between the first end plug 30 and the second end plug 40.

[0070] Figure 2A shows a side view of the first end plug or

[0071] Cooling medium distribution element 30 according to a possible embodiment, in which the first end plug 30 has an outer profile 31, a cooling medium distribution structure 32, 33, and a torque transmission element 34. In this exemplary embodiment, the outer profile 31 of the first end plug 30 has longitudinal elevations that run in the axial direction and have different lengths in the axial direction, so that the cooling medium can be introduced from the cooling channels formed by the inner tube 20 and the longitudinal grooves into the cooling medium distribution structure 32, 33. The end plug 30 further has a fit 36 ​​for a rotary bearing (e.g., a rolling bearing) of the electric machine.

[0072] Figure 2B shows another view of the first end plug 30 according to a possible embodiment, viewed along the axial or longitudinal direction of the rotor shaft. The exemplary embodiment has an outer profile 31 consisting of elevations periodically repeated around the circumference of the first end plug 30, with every second elevation being shorter to enable fluid communication between the cooling channels and the cooling medium distribution structure 32, 33.

[0073] Figure 2C shows a side view of the second end plug 40 according to a possible embodiment, in which the second end plug 40 also has an outer profile 41 and a cooling medium distribution structure 42. In this exemplary embodiment, the outer profile 41 of the second end plug 40, similar to that described above for the first end plug 30, has longitudinal elevations in the axial direction, which have different lengths in the axial direction. The end plug 40 further comprises a fit 46 for a rotary bearing (e.g., a rolling bearing) of the electric machine.

[0074] Figure 2D shows another view of the second end plug 40 according to a possible embodiment, viewed along the axial direction. The exemplary embodiment has an outer profile 41 consisting of elevations periodically repeating around the circumference of the second end plug 40, with each second elevation being shorter to enable fluid communication between the cooling channels and the cooling medium distribution structure 42.

[0075] Figure 3A shows a cross-section through a rotor shaft 1 according to a possible embodiment with a round inner tube 20 without profiling in the assembled state. In this exemplary embodiment, the casing tube 10 has a periodically repeating sequence of axially extending elevations and depressions around the circumference of the casing tube 10, which form the inner profile 11 of the casing tube 10. The elevations of the inner profile 11 are in contact with the outer surface of the inner tube 20. The free spaces in the longitudinal grooves or depressions of the inner profile 11, delimited by the casing tube 10 and the inner tube 20, define axially extending cooling channels for receiving a cooling medium, such as cooling water, oil, or even a cooled fuel, which can then be fed to an energy conversion system.

[0076] In another exemplary embodiment, Fig. 3B shows a cross-section through a rotor shaft 1 according to a possible embodiment with a profiled inner tube 20, wherein the elevations of the profiling of the inner tube 20 engage in some of the recesses or grooves of the inner profile 11 of the casing tube 10. In the exemplary embodiment shown, the elevations of the profile of the inner tube 20 are so pronounced that they engage positively in every second recess of the inner profile 11 of the casing tube 10 and thus the cooling channels run in every other second longitudinal groove of the inner profile 11 of the casing tube 10.

[0077] In one possible embodiment of the rotor shaft 1, the inner profile 11 of the casing tube 10 can have a profile depth in the range of 1.00 mm to 6.00 mm, preferably in the range of 1.5 mm to 3.5 mm, and the inner tube 20 can have either no profile at all (see, for example, Fig. 3A) or a profile depth in the range of 0.5 mm to 4.00 mm, preferably in the range of 1.5 mm to 3.5 mm.

[0078] Figure 4A shows a longitudinal section through a rotor shaft 1 according to an embodiment in which the first end plug or the cooling medium distribution element 30 has an inlet 35 and an outlet 33 for the cooling medium. The path of the cooling medium in the rotor shaft 1 is schematically illustrated by arrows. In the exemplary embodiment shown in Fig. 4A, the first end plug 30 has an inlet 35, through which the cooling medium is guided in the direction of the arrow inside the first end plug 30. The cooling medium reaches the cooling medium distribution structure 42 along the arrows shown through the cooling medium guide tube 50, which in the possible embodiment shown connects the inlet 35 of the first end plug 30 with the cooling medium distribution structure 42 of the second end plug 40.This guides the cooling medium in at least partially radially extending channels into the axially extending cooling channels, defined in the free spaces between the casing tube 10 and the inner tube 20. In the exemplary embodiment shown, the cooling channels guide the cooling medium from the second end plug 40 back towards the first end plug 30. The cooling medium distribution structure 32 of the first end plug 30 is connected to the cooling channels and can guide the cooling medium into the interior of the first end plug 30. The second part of the cooling medium distribution structure 33 of the first end plug 30 represents the outlet for the cooling medium. Thus, in this possible embodiment, the inlet and outlet of the cooling medium are located on the same end plug 30, which in some embodiments also has a torque transmission element.

[0079] Figure 4B shows a longitudinal section through the rotor shaft 1 according to another possible embodiment, in which the first end plug 30 has an inlet 35 for the cooling medium, which is connected to the cooling medium distribution structure 32, and the second end plug 40 has an outlet 45 for the cooling medium, which is connected to the cooling medium distribution structure 42 of the second end plug 40. The course of the cooling medium in the rotor shaft 1 is again schematically represented by arrows. In the illustrated embodiment, the cooling medium passes through the inlet 35 in the direction of the arrow into the interior of the first end plug 30. The inlet 35 is connected to the cooling medium distribution structure 32 of the first end plug 30, which guides the cooling medium in at least partially radially extending channels into the axially extending cooling channels defined in the free spaces between the casing tube 10 and the inner tube 20.The cooling channels guide the cooling medium from the first end plug 30 to the second end plug 40, where it is discharged from the cooling medium distribution structure.

[0080] 42 of the second end plug 40 to the outlet 45. Thus, in this possible embodiment, the inlet and outlet of the cooling medium are located at different end plugs.

[0081] Figure 4C shows a longitudinal section through a rotor shaft 1 according to an embodiment in which the second end plug 40 has an inlet 46 and an outlet

[0082] 43 for the cooling medium. The course of the cooling medium in the rotor shaft 1 is again schematically represented by arrows. In the illustrated embodiment, the cooling medium is guided in the direction of the arrow via the inlet 46 into the interior of the second end plug 40. Through the cooling medium guide tube 50, which in the illustrated embodiment connects the inlet 46 of the second end plug 40 with the cooling medium distribution structure 32 of the first end plug 30, the cooling medium passes along the illustrated arrows into the cooling medium distribution structure 32 of the first end plug 30. This cooling medium distribution structure 32 guides the cooling medium in at least partially radially extending channels into the axially extending cooling channels, defined in the free spaces between the jacket tube 10 and the inner tube 20. In the illustrated embodiment, the cooling channels guide the cooling medium from the first end plug 30 back toward the second end plug 40.The cooling medium distribution structure 42 of the second end plug 40 is also connected to the axial cooling channels and can guide the cooling medium into the interior of the second end plug 40. The cooling medium distribution structure 42 of the second end plug 40 guides the cooling medium to an outlet 43, through which the cooling medium exits the second end plug 40. Thus, in this possible embodiment, the inlet and outlet of the cooling medium are located at the second end plug 40. This has the advantage, among other things, that the first end plug 30, which has the torque transmission element 34, does not require any connections for the cooling medium, which can lead, among other things, to improved mechanical properties of the first end plug 30 and space savings for an electric drive system - e.g., a direct drive for motor vehicle wheels or a drive for an aircraft propeller - in which such an actively cooled rotor shaft 1 is used.

[0083] Figure 5A shows a longitudinal section through the embodiment of a rotor shaft 1, in which the first end plug 30 has the inlet 35 and the outlet 33 for the cooling medium and an element for electromagnetic force transmission 60 (such as a rotor laminated core with permanent magnets or with rotor windings), which is connected in a rotationally fixed, preferably force-locking, manner to part of the outer surface of the casing tube 10. The course of the cooling medium in the rotor shaft 1 and in the element for electromagnetic force transmission 60 is again shown schematically by arrows. The rotor shaft 1 together with the element for electromagnetic force transmission 60, which can have its own cooling channels 61, represents a rotor 2 of a rotating electrical machine 3. In the possible embodiment shown in Figure 5A, the cooling medium can reach the first end plug 30 via the inlet 35.Through a cooling medium guide tube 50, which in the illustrated possible embodiment connects the inlet 35 of the first end plug 30 with the cooling medium distribution structure 42 of the second end plug 40, the cooling medium reaches the cooling medium distribution structure 42 of the second end plug 40 along the arrows shown. This guides the cooling medium in at least partially radially extending channels into the axially extending cooling channels, defined in the free spaces between the jacket tube 10 and the inner tube 20 and into the cooling channels 61 of the element for electromagnetic force transmission 60. The cooling medium can pass from the second end plug 40 to the first end plug 30 via the cooling channels, where it can be received by the cooling medium distribution structure 32 of the first end plug 30 and guided to the outlet 33. Thus, in this possible embodiment, the inlet and outlet of the cooling medium are located on the same end plug.

[0084] Figure 5B shows a longitudinal section through the embodiment of the rotor shaft 1, in which the first end plug 30 has an inlet 35 for the cooling medium, which is connected to the cooling medium distribution structure 32 of the first end plug 30, and the second end plug 40 has an outlet 45 for the cooling medium, which is connected to the cooling medium distribution structure 42 and an element for electromagnetic force transmission 60, which is connected in a rotationally fixed, preferably non-positively, manner to a part of the outer surface of the casing tube 10. The course of the cooling medium in the rotor shaft and in the element for electromagnetic force transmission is schematically represented by arrows. The rotor shaft 1 together with the element for electromagnetic force transmission 60, which can have its own cooling channels 61, represents the rotor 2.The cooling medium can flow from the first end plug 30 to the second end plug 40 via the cooling channels, where it can be received by the cooling medium distribution structure 42 of the second end plug 30 and directed to the outlet 45. Thus, in this possible embodiment, the inlet and outlet of the cooling medium are located at different end plugs. An element for electromagnetic force transmission 60 with its own cooling channels 61 can also be combined with the embodiment of Fig. 4C.

[0085] The embodiments illustrated in Fig. 4A, Fig. 4B, Fig. 4C, Fig. 5A, and Fig. 5B are possible examples of the present disclosure. Further possible embodiments may, for example, include an inlet and an outlet for the cooling medium at the second end plug 40, or an inlet at the second end plug 40 and an outlet at the first end plug 30. Designs with multiple inlets and / or multiple outlets and / or designs with the cooling medium conduit opposite to the direction of the arrow shown, as well as other embodiments not mentioned, are also possible.

[0086] Figure 6 shows an electric machine 3 according to a possible embodiment with a rotor 2 and a stator 4. The rotor 2, comprising a rotor shaft 1 and an element for electromagnetic force transmission 60, which is connected to the rotor shaft 1 in a rotationally fixed, preferably non-positively, manner, according to one of the previously described embodiments or according to another embodiment, is rotatable relative to the stator 4 (e.g., using two rolling bearings) and has a torque transmission element 34. In one possible embodiment, one of the end plugs can be used for torque transmission through the positive or non-positive connection to the casing tube 10 or to the inner profile 11 of the casing tube 10. Figure 7A shows a side view of the components of a possible embodiment of a rotor shaft 1 with a tapered casing tube 10 with an inner profile 11, a profiled inner tube 20, and a cooling medium guide tube 50.In the possible embodiment shown, the casing tube 10 tapers at one end so that it has a smaller radius at one end than over the rest of the length of the casing tube 10. End plug In addition, the rotor shaft 1 has a first end plug 30 (i.e. a first cooling medium distribution element) and a second cooling medium distribution element 40. The first end plug 30 can have an outer profile 31 and the second cooling medium distribution element 40 can have an outer profile 41. In the exemplary embodiment shown, the second cooling medium distribution element 40 has a cooling medium distribution structure 42 for the cooling medium and the first end plug 30 has the cooling medium distribution structure 32, 33 for the inlet and outlet of the cooling medium (cf. Fig. 12A).

[0087] In the illustrated embodiment, the first end plug 30 further comprises a torque transmission element 34, via which the rotor shaft 1 can be connected, for example, to a wheel, propeller, gearbox, or the like to be driven. The taper 12 can be configured such that the second cooling medium distribution element 40 can be at least partially received in the taper 12 of the casing tube 10. The first end plug 30 in the illustrated embodiment is designed to be pressed into the casing tube 10. Just like other embodiments described herein, the individual components can each be made of metal, non-ferrous metal, steel, ceramic, plastic, natural material, and / or combinations thereof. Different components can be made of different and / or the same materials in order to optimize the respective properties, for example, with regard to component requirements, labor requirements, and / or material costs.The reshaped end, in this example a taper 12, of the jacket tube can not only replace part of the second end plug 40, as shown in Fig. 7A, but also in comparison to Fig. 1A. Other possible embodiments of the jacket tube 10 can have one or two reshaped ends that assume certain functions of at least one of the end plugs 30, 40, so that the respective end plug 30, 40 is an integral part of the jacket tube 10 and the corresponding end plug 30, 40 is not present as a separate component. The two ends of the jacket tube 10 can be different or identical.

[0088] Figure 7B shows a side view of the components of a possible embodiment of a rotor shaft 1 with a tapered casing tube 10 with inner profile 11, a profiled inner tube 20 and a cooling medium guide tube 50. Compared to the embodiment of Fig. 7A, the outer profile of the end plug 30 is significantly shortened, so that the rotationally fixed connection between the end plug 30 and the casing tube 10 is not achieved by pressing, but by welding or another suitable material-locking connection technology.

[0089] Figure 7C shows a side view of the rotor shaft 1 according to a possible embodiment, assembled from the components described in Fig. 7A and Fig. 7B, in which the tapered casing tube 10 is connected in a rotationally fixed manner to the first end plug or cooling medium distribution element 30, wherein the first end plug 30 can have a torque transmission element 34. The second cooling medium distribution element 40 is arranged inside the tapered part 12 of the casing tube and is therefore not visible in Figure 7C. The connection between the casing tube 10 and the end plug 30 can be made, for example, by pressing and / or welding, wherein the first end plug 30 engages in some of the plurality of longitudinal grooves of the inner profile 11 of the casing tube 10, for example so that the elevations of the outer profile 31 engage in those of the inner profile 11.The inner tube 20 and the coolant guide tube 50 are located, not visible in this view, coaxial with the casing tube 10 inside the casing tube 10 and at least partially between the first end plug 30 and the second coolant distribution element 40 (also not visible). Since the rotor shaft engages with a rotary bearing of the electric machine at the tapered end 12 of the casing tube, the second coolant distribution element 40—unlike the first end plug 30—does not have to withstand strong mechanical loads and can therefore—like the inner tube and the coolant guide tube—be made of an inexpensive and lightweight material such as a suitable plastic (e.g., PEEK) or aluminum.

[0090] Figure 8 shows a side view of the first end plug 30 according to the exemplary embodiment shown in Fig. 7B. The exemplary first end plug 30 shown has a significantly shortened outer profile compared to the embodiment of Fig. 2A, since the connection of the first end plug 30 to the casing tube 10 is established by welding. Furthermore, the first end plug 30 has a cooling medium distribution structure 32, 33, a fit 36 ​​for a rotary bearing of the electric machine, and a torque transmission element 34.

[0091] Figure 9A shows a possible design of a casing tube 10 with an inner profile 11 and a taper 12 at one end of the casing tube 10. The inner profile is designed such that the longitudinal cracks defined by the inner profile run helically along the longitudinal axis of the casing tube 10. The angle at which the longitudinal cracks are aligned with the axial direction of the casing tube 10 can be any angle at which effective longitudinal transport of the cooling medium occurs.

[0092] Figure 9B shows a side view of the cut-open jacket pipe 10 with taper 12 of Fig. 9A in which the helical course of the longitudinal cracks of the inner profile 11 is visible.

[0093] Figure 9C shows a possible design of a casing tube 10 with an inner profile 11. The inner profile is designed such that the longitudinal cracks defined by the inner profile run helically along the longitudinal axis of the casing tube 10, thus realizing an alternative, effective longitudinal transport of the cooling medium. The angle at which the longitudinal cracks are aligned with the axial direction of the casing tube 10 can be any other angle at which effective longitudinal transport of the cooling medium occurs.

[0094] Figure 10A shows a cross-sectional view through the casing tube 10 and inner tube 20 of a rotor shaft 1 according to a possible embodiment with a profiled inner tube 20 having a cross-section with threefold rotational symmetry. The elevations of the profiling of the inner tube 20 are designed such that they engage with some of the recesses of the inner profile n of the casing tube 10. The casing tube 10 is designed such that it also has a cross-section with threefold rotational symmetry. The deviation from a circular cross-section prevents the relative rotation of the inner tube 20 and the casing tube 10.

[0095] Figure 10B shows a cross-sectional view through the casing tube 10 and inner tube 20 of a rotor shaft 1 according to a possible embodiment with a hexagonal inner tube 20 and an outer tube, the inner profile of which is configured such that its elevations rest against the outside of the inner tube. The exemplary inner profile 11 of the casing tube has a sinusoidal profile along an approximately hexagonal shape of the inside of the casing tube 10. In the illustrated embodiment, every third elevation of the inner profile n of the casing tube 10 is configured to rest against a respective corner of the hexagonal inner tube 20. In addition, each of the elevations that rest against a respective corner of the inner tube 20 has a central recess to accommodate the corner and thus prevent relative rotation of the inner tube 20 and the casing tube 10.

[0096] Fig. ii shows a side view of the components of a rotor shaft i according to a possible embodiment of the present disclosure. This comprises a non-profiled casing tube io with a taper 12 at one end of the casing tube 10, for example with a wall thickness in the range of 2.00 mm to 10.00 mm, with a smooth inside and outside. The illustrated embodiment also comprises a profiled inner tube 20, for example with a wall thickness of 0.5 mm to 5.00 mm, a first end plug 30, a second cooling medium distribution element 40, and a cooling medium guide tube 50. The first end plug 30 can have an outer profile 31, and the second cooling medium distribution element 40 can have an outer profile 41.

[0097] In the illustrated embodiment, the second cooling medium distribution element 40 has a cooling medium distribution structure 42 for the cooling medium, and the first end plug 30 has the cooling medium distribution structure 32, 33. In the illustrated embodiment, the first end plug 30 further has a torque transmission element 34, via which the rotor shaft 1 can be connected, for example, to a wheel to be driven, propeller, gearbox, or the like. Other corresponding embodiments can, for example, comprise other outer profiles 31, 41 of the end plugs 30, 40, other cooling medium distribution structures 32, 33, 42, and / or other torque transmission elements 34, and / or can dispense with the use of the cooling medium guide tube 50. At least one of the end plugs 30, 40 can be connected, for example, by welding, to the casing tube 10, the inner tube 20, and / or the cooling medium guide tube 50.The taper 12 can be configured such that the second cooling medium distribution element 40 can be at least partially received in the taper 12 of the jacket tube 10. The first end plug 30 in the illustrated embodiment is designed to be welded and / or pressed to the jacket tube 10 to establish a rotationally fixed connection.

[0098] Figure 12A shows a longitudinal section through a rotor shaft 1 according to an embodiment in which the first end plug or the cooling medium distribution element 30 has an inlet 35 and an outlet 33 for the cooling medium. The course of the cooling medium in the rotor shaft 1 is schematically represented by arrows. In the embodiment shown, the first end plug 30 is as shown in Figure 4A. In the exemplary embodiment shown in Figure 12A, the first end plug 30 has an inlet 35, through which the cooling medium is guided in the direction of the arrow inside the first end plug 30. The cooling medium flows into the cooling medium distribution structure 42 along the arrows shown through the cooling medium guide tube 50, which in the possible embodiment shown connects the inlet 35 of the first end plug 30 to the cooling medium distribution structure 42 of the second end plug 40 (also described herein as a cooling medium distribution element).The second cooling medium distribution element 40 is located inside the taper 12 of the casing tube 10, which has a fit for a rotary bearing of the electrical machine.

[0099] The cooling medium distribution structure 42 directs the cooling medium in at least partially radially extending channels into the axially extending cooling channels, defined in the free spaces between the casing tube 10 and the inner tube 20. In the exemplary embodiment shown, the cooling channels direct the cooling medium from the second end plug 40 back towards the first end plug 30. The cooling medium distribution structure 32 of the first end plug 30 is connected to the cooling channels and can direct the cooling medium into the interior of the first end plug 30. The second part of the cooling medium distribution structure 33 of the first end plug 30 represents the outlet for the cooling medium. Thus, in this possible embodiment, the inlet and outlet of the cooling medium are located on the same end plug 30, which in some embodiments also has a torque transmission element 34.

[0100] Figure 12B shows a longitudinal section through the rotor shaft 1 according to another possible embodiment, in which the first end plug 30 has an inlet 35 for the cooling medium, which is connected to the cooling medium distribution structure 32, and the second end plug 40 has an outlet 45 for the cooling medium, which is connected to the cooling medium distribution structure 42 of the second end plug 40. In the embodiment shown, the first end plug 30 is as shown in Figure 4B. The path of the cooling medium in the rotor shaft 1 is again schematically represented by arrows. In the embodiment shown, the cooling medium flows through the inlet 35 into the interior of the first end plug 30 in the direction of the arrow.The inlet 35 is connected to the cooling medium distribution structure 32 of the first end plug 30, which guides the cooling medium in at least partially radially extending channels into the axially extending cooling channels defined in the free spaces between the jacket tube 10 and the inner tube 20. The cooling channels guide the cooling medium from the first end plug 30 to the second end plug 40, where it is discharged from the cooling medium distribution structure.

[0101] 42 of the second end plug 40 to the outlet 45. Thus, in this possible embodiment, the inlet and outlet of the cooling medium are located at different end plugs. The second cooling medium distribution element 40 is located inside the taper 12 of the casing tube 10, which has a fit for a rotary bearing of the electric machine.

[0102] Figure 12C shows a longitudinal section through a rotor shaft 1 according to an embodiment in which the second end plug 40 has an inlet 46 and an outlet

[0103] 43 for the cooling medium. The course of the cooling medium in the rotor shaft 1 is again schematically illustrated by arrows. In the illustrated embodiment, the cooling medium is guided in the direction of the arrow via the inlet 46 into the interior of the second end plug 40. Through the cooling medium guide tube 50, which in the illustrated embodiment connects the inlet 46 of the second end plug 40 with the cooling medium distribution structure 32 of the first end plug 30, the cooling medium passes along the illustrated arrows into the cooling medium distribution structure 32 of the first end plug 30. This cooling medium distribution structure 32 guides the cooling medium in at least partially radially extending channels into the axially extending cooling channels, defined in the free spaces between the casing tube 10 and the inner tube 20.In the illustrated embodiment, the cooling channels guide the cooling medium from the first end plug 30 back towards the second end plug 40 (also described herein as a cooling medium distribution element). The cooling medium distribution structure 42 of the second end plug 40 is also connected to the axial cooling channels and can guide the cooling medium into the interior of the second end plug 40. The second cooling medium distribution element 40 is located inside the taper 12 of the casing tube 10, which has a fit for a rotary bearing of the electrical machine. The cooling medium distribution structure 42 of the second end plug 40 guides the cooling medium to an outlet 43, via which the cooling medium exits the second end plug 40. Thus, in this possible embodiment, the inlet and outlet of the cooling medium are located at the second end plug 40. This has, among other things,the advantage that the first end plug 30, which has the torque transmission element 34, does not require any connections for the cooling medium, which can lead, among other things, to improved mechanical properties of the first end plug 30 and space savings for an electric drive system - e.g. a direct drive for motor vehicle wheels or a drive for an aircraft propeller - in which such an actively cooled rotor shaft 1 is used.

[0104] Fig. 13A shows a longitudinal section through the embodiment of a rotor shaft 1, in which the first end plug 30 has the inlet 35 and the outlet 33 for the cooling medium and an element for electromagnetic force transmission 60, which is connected in a rotationally fixed, preferably force-locking, manner to part of the outer surface of the casing tube 10. The course of the cooling medium in the rotor shaft 1 and in the element for electromagnetic force transmission 60 is again schematically represented by arrows. The rotor shaft 1 together with the element for electromagnetic force transmission 60, which can have its own cooling channels 61, represents a rotor 2 of a rotating electrical machine 3. In the possible embodiment shown in Figure 13A, the cooling medium can reach the first end plug 30 via the inlet 35.Through a cooling medium guide tube 50, which in the illustrated possible embodiment connects the inlet 35 of the first end plug 30 with the cooling medium distribution structure 42 of the second end plug 40, the cooling medium flows along the arrows shown into the cooling medium distribution structure 42 of the second end plug 40. The second cooling medium distribution element 40 is located inside the taper 12 of the jacket tube 10, which has a fit for a rotary bearing of the electric machine. The cooling medium distribution structure 42 guides the cooling medium in at least partially radially extending channels into the axially extending cooling channels defined in the free spaces between the jacket tube 10 and the inner tube 20 and into the cooling channels 61 of the electromagnetic force transmission element 60.The cooling medium can flow from the second end plug 40 to the first end plug 30 via the cooling channels, where it can be received by the cooling medium distribution structure 32 of the first end plug 30 and directed to the outlet 33. Thus, in this possible embodiment, the inlet and outlet of the cooling medium are located on the same end plug.

[0105] Figure 13B shows a longitudinal section through the embodiment of the rotor shaft 1, in which the first end plug 30 has an inlet 35 for the cooling medium, which is connected to the cooling medium distribution structure 32 of the first end plug 30, and the second end plug 40 has an outlet 45 for the cooling medium, which is connected to the cooling medium distribution structure 42 and an element for electromagnetic force transmission 60, which is connected in a rotationally fixed, preferably non-positively, manner to a part of the outer surface of the casing tube 10. The course of the cooling medium in the rotor shaft and in the element for electromagnetic force transmission is schematically represented by arrows. The rotor shaft 1 together with the element for electromagnetic force transmission 60, which can have its own cooling channels 61, represents the rotor 2.The cooling medium can flow from the first end plug 30 to the second end plug 40 via all cooling channels, where it can be received by the cooling medium distribution structure 42 of the second end plug 30 and directed to the outlet 45. Thus, in this possible embodiment, the inlet and outlet of the cooling medium are located at different end plugs. The second cooling medium distribution element 40 is located inside the taper 12 of the casing tube 10, which has a fit for a rotary bearing of the electric machine. In the exemplary embodiments of Figures 12A to 13B, the first end plug 30 is structurally identical to Figures 4A to 5C and is connected to the casing tube 10 by pressing, while the embodiments differ in the design of the cooling medium distribution element 40.This can be realized either as an end plug 40 (Figures 4A - 5C) or as a cooling medium distribution element 40, which is at least partially received by the taper 12 of the jacket tube 10.

[0106] Further exemplary embodiments

[0107] Further possible embodiments are described below:

[0108] 1. A rotor shaft for a rotor of an electrical machine, comprising: a casing tube having an inner profile with a plurality of longitudinal grooves; an inner tube arranged inside the casing tube; and first and second end plugs, each of which is positively and non-positively connected or positively and materially connected to one end of the casing tube by engaging in a portion of the plurality of longitudinal grooves; wherein the inner profile of the casing tube and the outer side of the inner tube define a plurality of cooling channels through which a cooling medium can flow along the casing tube.

[0109] 2. Rotor shaft according to embodiment 1, wherein at least one of the two end plugs has a torque transmission element.

[0110] 3. Rotor shaft according to one of embodiments 1 or 2, wherein the inner profile of the casing tube has periodically repeating elevations and depressions along the circumference of the casing tube.

[0111] 4- Rotor shaft according to one of embodiments 1 to 3, wherein the inner tube engages in a portion of the plurality of longitudinal grooves. 5. Rotor shaft according to embodiment 4, wherein the inner tube has a cross-section with periodically repeating elevations and depressions along its circumference, and the elevations engage in the portion of the longitudinal cracks of the inner profile of the casing tube.

[0112] 6. Rotor shaft according to one of the preceding embodiments 1 to 5, wherein the jacket tube has a wall thickness in the range of 2.00 mm to 10.00 mm; and / or wherein the inner tube has a wall thickness in the range of 0.5 mm to 5.00 mm.

[0113] 7. Rotor shaft according to one of the preceding embodiments 1 to 6, wherein the inner profile of the jacket tube has a profile depth in the range of 1.00 mm to 6.00 mm, preferably in the range of 1.5 mm to 3.5 mm, and / or wherein the inner tube has a profile depth in the range of 0.5 mm to 4.00 mm, preferably in the range of 1.5 mm to 3.5 mm.

[0114] 8. Rotor shaft according to one of the preceding embodiments 1 to 7, wherein one or both of the end plugs has an outer profile which fits into the

[0115] inner profile of the casing pipe; and / or wherein the end plugs are pressed onto the casing pipe; and / or wherein the end plugs are welded to the casing pipe.

[0116] 9. Rotor shaft according to one of the preceding embodiments 1 to 8, wherein the end plugs each have a cooling medium distribution structure which is connected to one of the cooling channels defined by the inner profile of the jacket tube and the outer side of the inner tube.

[0117] 10. Rotor shaft according to embodiment 9, wherein one of the end plugs has an inlet for the cooling medium which is connected to the cooling medium distribution structure and the other end plug has an outlet for the cooling medium which is connected to the cooling medium distribution structure.

[0118] 11. The rotor shaft according to embodiment 9, further comprising a cooling medium guide tube arranged within the inner tube and connecting the two end plugs to each other such that the cooling medium can flow from one end plug to the other through the cooling medium guide tube; and wherein one of the end plugs has an inlet and an outlet for the cooling medium, wherein the outlet is connected to the cooling medium distribution structure and the inlet is connected to the cooling medium guide tube.

[0119] 12. Rotor shaft according to embodiment 2 and embodiment io or embodiment n, wherein the end plug having the inlet for the cooling medium also has the torque transmission element.

[0120] 13. A rotor for an electric machine comprising: a rotor shaft according to one of the preceding embodiments 1 to 12; and an element for electromagnetic force transmission, which is connected in a rotationally fixed, preferably non-positively, manner to a part of the outer surface of the casing tube.

[0121] 14. Rotor according to embodiment 13 comprising a rotor shaft according to one of embodiments 9 to 12, wherein the element for electromagnetic force transmission has at least one cooling channel which is connected to the cooling medium distribution structure of both end plugs.

[0122] 15. An electric machine comprising: a stator; and a rotor according to one of the preceding embodiments 13 or 14.

Claims

Patent claims 1. A rotor shaft (1) for a rotor of an electrical machine (3), comprising: a casing tube (10); an inner tube (20) arranged inside the casing tube; and two cooling medium distribution elements (30, 40), each arranged at one end of the rotor shaft; wherein the casing tube has an inner profile (11) with a plurality of longitudinal grooves and / or the inner tube has an outer profile with a plurality of longitudinal grooves; and wherein the inner profile of the casing tube and / or the outer profile of the inner tube define a plurality of cooling channels through which a cooling medium can flow along the rotor shaft from one cooling medium distribution element to the other cooling medium distribution element.

2. Rotor shaft according to claim 1, wherein at least one of the two cooling medium distribution elements has a torque transmission element (34).

3. Rotor shaft according to one of the preceding claims, wherein the inner profile of the casing tube along the circumference of the casing tube and / or the outer profile of the inner tube along the circumference of the inner tube has periodically repeating elevations and depressions.

4. Rotor shaft according to one of the preceding claims, wherein the inner tube engages in a part of the plurality of longitudinal grooves of the inner profile of the casing tube.

5. Rotor shaft according to the preceding claim 4, wherein the inner tube has a cross-section with periodically repeating elevations and depressions along its circumference and the elevations engage in the part of the longitudinal grooves of the inner profile of the casing tube.

6. Rotor shaft according to one of the preceding claims, wherein the jacket tube has a wall thickness in the range of 2.00 mm to 10.00 mm; and / or wherein the inner tube has a wall thickness in the range of 0.5 mm to 5.00 mm.

7. Rotor shaft according to one of the preceding claims, wherein the inner profile of the casing tube has a profile depth in the range of 1.00 mm to 6.00 mm, preferably in the range of 1.5 mm to 3.5 mm, and / or wherein the inner tube has a profile depth in the range of 0.5 mm to 4.00 mm, preferably in the range of 1.5 mm to 3.5 mm.

8. Rotor shaft according to one of the preceding claims, wherein the cooling medium distribution elements are each connected to one end of the casing tube in a form-fitting and non-positive manner or in a form-fitting and material-fitting manner by engaging in a part of the plurality of longitudinal grooves.

9. Rotor shaft according to claim 8, wherein one or both of the cooling medium distribution elements have an outer profile (31, 41) that engages the inner profile of the casing tube; and / or wherein one or both of the cooling medium distribution elements are pressed onto the casing tube; and / or wherein one or both of the cooling medium distribution elements are welded to the casing tube.

10. Rotor shaft according to one of the preceding claims, wherein the cooling medium distribution elements each have a cooling medium distribution structure (32, 33, 42) which is connected to one or more of the cooling channels defined by the inner profile of the jacket tube and / or by the outer profile of the inner tube.

11. Rotor shaft according to claim 10, wherein one of the cooling medium distribution elements has an inlet (35) for the cooling medium, which is connected to the associated cooling medium distribution structure and the other cooling medium distribution element has an outlet (45) for the cooling medium, which is connected to the associated cooling medium distribution structure.

12. The rotor shaft according to claim 10, further comprising a cooling medium guide tube (50) arranged within the inner tube and connecting the two cooling medium distribution elements to one another such that the cooling medium can flow from one cooling medium distribution element to the other through the cooling medium guide tube; and wherein one of the cooling medium distribution elements has an inlet (35) and an outlet for the cooling medium, wherein the outlet is connected to the associated cooling medium distribution structure and the inlet is connected to the cooling medium guide tube.

13. Rotor shaft according to claim 2 and claim 11 or 12, wherein the cooling medium distribution element, which has the inlet for the cooling medium, also has the torque transmission element.

14. Rotor shaft according to claim 2 and claim 12, wherein the cooling medium distribution element comprising the torque transmission element has neither an inlet nor an outlet for the cooling medium.

15. Rotor shaft according to one of the preceding claims, wherein the casing tube has a fit for a rotary bearing of the electric machine at at least one end.

16. The rotor shaft of claim 15, wherein the casing tube has a taper at at least one end configured to receive the cooling medium distribution element inside the casing tube and to function as the running surface for the rotary bearing of the electric machine.

17. A rotor for an electrical machine comprising: a rotor shaft according to one of the preceding claims 1 to 16; and an element for electromagnetic force transmission, which is connected in a rotationally fixed, preferably non-positively, manner to a part of the outer surface of the casing tube.

18. Rotor according to claim 17, comprising a rotor shaft according to one of the preceding claims 10 to 16, wherein the element for electromagnetic force transmission has at least one cooling channel which is connected to the cooling medium distribution structure of both cooling medium distribution elements.

19. An electrical machine comprising: a stator; and a rotor according to one of claims 17 or 18.

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