Rotor shaft with integrated cooling ducts

Abstract

The present disclosure relates to a rotor shaft for an electric machine rotor. The rotor shaft includes an outer sleeve, an inner sleeve disposed inside the outer sleeve, and two coolant distribution elements, each disposed at one end of the rotor shaft. The outer sleeve has an internal contour with multiple longitudinal grooves. Alternatively or additionally, the inner sleeve has an external contour with multiple longitudinal grooves. The internal contour of the outer sleeve and / or the external contour of the inner sleeve define multiple cooling channels through which coolant can flow from one coolant distribution element to another along the rotor shaft. The present disclosure further relates to an electric machine rotor including the disclosed rotor shaft and an associated electric machine.

Description

[Technical Field]

[0001] 1.Technical Field The present disclosure relates to a rotor shaft for an electric machine, such as an electric motor or generator, having integrated cooling ducts. [Background technology]

[0002] 2. Prior art Rotor shafts of rotating electrical machines, such as electric motors or generators, generate heat during their use. The resulting heat can be transferred to, for example, the stator and / or rotor windings. This can lead to undesirable material deformation and reduce the efficiency of the electrical machine. To prevent this, the heat generation can be counteracted by passive or active cooling. An example of this is air cooling, in which air is guided over and / or through the electrical machine. Another approach is active cooling of the rotor via a liquid cooling medium.

[0003] Various rotor shafts with active cooling are known from the prior art. For example, German Patent Application No. 10 2019 207 325 A1 describes a cooling device for heat-generating rotating components of an electric machine, in which a rotatably mounted hollow shaft connected in a rotationally fixed manner to a rotor shaft has at least one cooling duct for cooling a lubricant, the at least one cooling duct comprising a hollow shaft duct, a supply duct and an outlet duct.

[0004] US Patent Application Publication No. 2020 / 0251963 describes an electric machine with a single-piece hollow rotor shaft through which a liquid coolant can flow and on which a plurality of heat dissipation ribs are arranged.

[0005] German Patent Application No. 10 2016 202 416 A1 discloses a rotor shaft arrangement for a rotor of an electric motor, which comprises a hollow shaft for receiving a rotor body and a heat sink arranged within the hollow shaft, the heat sink having radially extending cooling ribs and being in radial thermal contact with the hollow shaft. The heat sink has an axially continuously open structure, so that a cooling medium can flow axially through the heat sink within the hollow shaft, the open structure being formed by defined ducts.

[0006] German Patent Application Publication No. 10 2017 112 348 A1 relates to an electric machine comprising a rotor rotatable relative to a stator and having at least one rotor shaft, and a duct system through which a coolant can flow to cool the machine. The duct system extends at least partially within the rotor shaft. In this case, the duct system comprises cooling ducts designed to extend at least partially conically in the longitudinal direction of the rotor shaft, so that the coolant can be transported in a direction in which the duct diameter increases due to the rotational movement of the rotor shaft.

[0007] Further rotor shafts known from the prior art are disclosed in DE 11 2010 004 773, US 9,148,041, EP 3 384 581, DE 10 2017 112 348, DE 10 2020 207 431, EP 3 507 889, DE 10 2019 108 943, EP 3 555 992, EP 3 598 611, EP 3 961 875, US 7,579 725, EP 1 953 896, DE 10 2017 202 356, U.S. Pat. No. 9,331,552, EP Pat. No. 3 303 039, EP Pat. No. 3 673 568, EP Pat. No. 3 501 085, DE Pat. No. 10 2016 209 173, EP Pat. No. 3 152 819, DE Pat. No. 10 2016 208 770 and EP Pat. No. 3 433 919. Summary of the Invention [Problem to be solved by the invention]

[0008] 3. Disclosure Overview However, rotor shafts known from the prior art have several drawbacks. In particular, some of the rotor shafts known from the prior art can only be manufactured at high operating costs, material wear, and consequently high costs. Furthermore, the cooling methods known from the prior art are often insufficient for use in small electric motors, especially those with high power densities.

[0009] Some of the known rotor shaft cooling structures are also complex, delicate and / or multi-part designs, which can result in increased waste in production and reduced product life. [Means for solving the problem]

[0010] The present application is therefore based on the problem of at least partially reducing some of the stated drawbacks of the prior art. This problem is at least partially solved by the subject matter of the independent claims. Exemplary embodiments are set out in the dependent claims. Unless otherwise stated, material properties shall be determined in accordance with the relevant standards.

[0011] In one embodiment, the present disclosure provides a rotor shaft for a rotor of an electric machine. The rotor shaft includes a casing tube, an inner tube disposed inside the casing tube, and two cooling medium distribution elements. Each of the cooling medium distribution elements is disposed at one end of the rotor shaft. The casing tube has an inner contour with a plurality of longitudinal grooves, and / or the inner tube has an outer contour with a plurality of longitudinal grooves. Furthermore, the inner contour of the casing tube and / or the outer contour of the inner tube define a plurality of cooling ducts through which cooling medium can flow from one of the cooling medium distribution elements to the other along the rotor shaft.

[0012] The coolant distribution elements may be configured as end plugs in some embodiments, as described below.

[0013] In a further exemplary embodiment, the rotor shaft comprises a casing tube having an inner contour with a plurality of longitudinal grooves, an inner tube disposed inside the casing tube, and first and second cooling medium distribution elements or first and second end plugs, each connected to one end of the casing tube by form-fitting and press-fitting or by form-fitting and integral bonding by engaging with portions of the plurality of longitudinal grooves, and the inner contour of the casing tube and the exterior of the inner tube define a plurality of cooling ducts through which cooling medium can flow along the casing tube.

[0014] Form-fit and press-fit, or form-fit and integrally bonded connections, in the context of this application also include combined form-fit, press-fit and integrally bonded connections.

[0015] The tube-in-tube design described above significantly simplifies the construction and manufacturing of actively cooled rotor shafts while simultaneously improving cooling. Furthermore, high torque can be transmitted through a form-fit and press fit between the contoured casing tubes and the cooling medium distribution elements / end plugs, while cooling ducts can be defined along the longitudinal grooves in the inner contour of the casing tubes and / or the outer contour of the inner tube.

[0016] This simplification of the rotor shaft design has many advantages, including the fact that no additional torque transmission elements are required, resulting in material and weight savings. The dual function of the inner contour of the casing tube - firstly, the definition of the axially extending cooling ducts, and secondly, the form-fitting and press-fitting associated with the cooling medium distribution elements - requires less work and allows the casing tube to be manufactured separately from the other components of the rotor shaft.

[0017] The inner tube and casing tube may be cold-formed, e.g., drawn, metal tubes manufactured from common materials such as, for example, E355 and 42CrMo4, structural steel, heat-treated steel and / or hardened steel.

[0018] The cooling medium distribution elements can be manufactured, for example, by forging, additive manufacturing, or machining. As a result, the manufacturing method of the casing tube can be changed in a simple and appropriate manner to manufacture modified embodiments of the casing tube for new rotor shafts, for example, with casing tubes of different lengths, diameters, thicknesses, and / or profiles of different types and depths. In particular, one or both cooling medium distribution elements can be used directly for torque transmission by form-fitting or press-fit connection to the casing tube or the inner profile of the casing tube, significantly simplifying the construction of the rotor shaft.

[0019] To further reduce weight and manufacturing complexity, the casing tube may have a tapered portion at one (or both) ends designed to receive one (or both) of the cooling medium distribution elements inside the casing tube and function as or include a fitting or bearing seat for the rotary bearings of the electric machine (see FIGS. 11-13B). In such an embodiment, the cooling medium distribution element located inside the tapered portion may be manufactured from a lightweight material, such as plastic (e.g., PEEK). The inner tube may also be manufactured from 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. As a result of this arrangement, the manufacture of the other components of the rotor shaft, i.e., the casing tube, the inner tube, the other cooling medium distribution elements and, where appropriate, the cooling medium guide tubes, remains independent of the specific embodiment of the torque transmission element.

[0021] To simplify the manufacture of the casing tube, for example by axial cold forming or cold drawing of the tube, and the connection to the cooling medium distribution elements, the inner contour of the casing tube along its circumference can have periodically repeating ridges and depressions, for example in the form of a sinusoidal wave, which further allows for a uniform distribution of the cooling medium for cooling the rotor shaft.

[0022] The inner tube can engage with some of the longitudinal grooves to achieve a form-fit connection between the inner tube and the casing tube for defining the cooling ducts in a simple manner. As a result of this arrangement, undesired positioning and / or rotation of the inner tube and the casing tube relative to each other is impossible. Furthermore, this arrangement allows the inner tube and the outer tube to be connected in a material- and labor-saving manner. Furthermore, the cooling medium is thus uniformly distributed through the rotor shaft to cool the rotor shaft.

[0023] In other embodiments, one or both of the coolant distribution elements may be rotationally fixedly welded to the casing tube without engaging the longitudinal groove.

[0024] Additionally, the inner tube can have a cross-section with periodically repeating ridges and depressions along its circumference, with the ridges of the inner tube engaging portions of the longitudinal grooves of the inner profile of the casing tube (see also Figures 1A and 3B). Like the possible periodic profile of the casing tube, the periodically repeating ridges of the inner tube allow for uniform distribution of the cooling medium for cooling the rotor shaft. Furthermore, such periodic profiles of the inner tube and casing tube can facilitate assembly because, due to symmetry, there are multiple relative positions where the two profiles engage with each other.

[0025] In one possible embodiment, the casing 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, firstly, ensure high structural stability for transmitting high torque, and secondly, allow for the manufacture of components with reduced material usage. This thickness range allows the same manufacturing method to be used in different embodiments, for example, but not limited to, for tubes of different thicknesses, profiles, or lengths, with slight and appropriate adaptations.

[0026] Furthermore, in one possible embodiment, the inner profile of the casing 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. These ranges of profile depths are distinguished by the fact that the flow behavior of the cooling medium can be advantageously tailored to the respective system requirements, with regard to laminar or turbulent flow dynamics. Furthermore, such profile depths ensure sufficient rotational strength of the cooling medium distribution elements to transmit high torques. In particular, such profile depths ensure that turbulence can be created despite a high cooling medium mass flow rate, thereby optimizing cooling efficiency.

[0027] To improve the connection of the cooling medium distribution elements to the casing tube, in one possible embodiment, one or both cooling medium distribution elements can have an outer contour that engages with the inner contour of the casing tube and / or the cooling medium distribution elements can be pressed onto the casing tube. The interlocking of the outer contour of the cooling medium distribution elements with the inner contour of the casing tube uses an advantageous form-fitting technique that uses the existing contour of the casing tube to define the cooling ducts. This type of form-fitting saves material because no additional fastening means are required, saving labor in production. Alternatively or additionally, the cooling medium distribution elements can be welded to the casing tube.

[0028] To guide the cooling medium through the cooling ducts defined by the inner tube and the casing tube, in some embodiments, the cooling medium distribution elements can each have a cooling medium distribution structure connected to one of the cooling ducts defined through the inner contour of the casing tube and the outside of the inner tube. As a result, no additional cooling medium supply is required, complicating the structure of the rotor shaft, and the manufacture of the casing tube and the inner tube remains largely unaffected by the specific embodiment of the cooling medium supply. Furthermore, the positioning of the cooling medium distribution structure within the cooling medium distribution element allows for different architectures of cooling medium guidance through the rotor shaft (see FIGS. 4A, 4B, and 4C, and FIGS. 12A, 12B, and 12C), and, if appropriate, different architectures of cooling medium guidance with additional elements attached to the rotor shaft, such as elements for electromagnetic power transmission, such as permanent magnets or rotor laminations with rotor windings (see FIGS. 5A and 5B, and FIGS. 13A and 13B).

[0029] In terms of accessibility of the inlet and outlet devices depending on the arrangement of the rotor shaft, in some embodiments it may be advantageous for the cooling medium guidance if one cooling medium distribution element has an inlet for the cooling medium connected to the cooling medium distribution structure and the other cooling medium distribution element has an outlet for the cooling medium connected to the cooling medium distribution structure (see also Figures 4B and 5B, and Figures 12A and 12B).

[0030] Alternatively, in other embodiments, it may also be advantageous in other possible fields of application if the cooling medium guide tube is arranged within the inner tube and connects two cooling medium distribution elements to each other so that the cooling medium can flow from one cooling medium distribution element to the other through the cooling medium guide tube, one of the cooling medium distribution elements having a cooling medium inlet and outlet, the outlet being connected to the cooling medium distribution structure and the inlet being connected to the cooling medium guide tube, or vice versa (see also Figures 4A, 4C and 5A, as well as Figures 12A, 12C and 13A).

[0031] In one possible embodiment of the rotor shaft, the cooling medium distribution element with the cooling medium inlet also has the torque transmission element (see FIGS. 4A, 5A, 12A and 13A). This arrangement can be advantageously combined, for example, if the cooling medium inlet is arranged coaxially inside the torque transmission element. In general, the individual components can therefore be arranged in a space- and material-saving manner.

[0032] In a further embodiment of the rotor shaft, the cooling medium distribution element with the torque transmission element does not have an external inlet or outlet for the cooling medium (see Figures 4C and 12C), allowing for a more compact drive system.

[0033] The present application also relates to a rotor for an electric machine, comprising a rotor shaft as described above and an electromagnetic power transmission element connected to a portion of the outer surface of the casing tube in a rotationally fixed manner, preferably by press-fitting. The electromagnetic power transmission element is thus located in the vicinity of a cooling duct in the casing tube, which can advantageously influence the temperature within the electromagnetic power transmission element. Furthermore, no additional support elements are required for fastening the electromagnetic power transmission element. The electromagnetic power transmission element can therefore also be cooled by rotor cooling, which improves the efficiency of the machine, particularly in the case of non-permanently excited machines such as asynchronous machines.

[0034] To improve the cooling of the electromagnetic power transmission element, it may be advantageous for the electromagnetic power transmission element to also have at least one cooling duct connected to the cooling medium distribution structures of the two cooling medium distribution elements (see Figures 5A and 5B and Figures 13A and 13B). This can reduce the heat generation of the entire rotor and achieve even higher efficiency.

[0035] The present application further relates to an electric machine comprising a stator and a rotor as described above. [Brief explanation of the drawings]

[0036] [Figure 1A] FIG. 2 is a side view of a rotor shaft component according to an exemplary embodiment of the present disclosure. [Figure 1B] FIG. 1B is a side view of the assembled rotor shaft of FIG. 1A. [Figure 2A] FIG. 1 is a side view of a first end plug according to a possible embodiment of the present disclosure. [Figure 2B] FIG. 2B is a side view of the first end plug of FIG. 2A. [Figure 2C] FIG. 10 is a side view of a second end plug according to a possible embodiment of the present disclosure. [Figure 2D] FIG. 2D is a side view of the second end plug of FIG. 2C. [Figure 3A] 10A and 10B are cross-sectional views of a rotor shaft according to a possible embodiment having a circular, non-profiled inner tube. [Figure 3B] 10 is a cross-sectional view of a rotor shaft according to a possible embodiment having a profiled inner tube, in which the ridges of the inner tube profile engage some of the depressions of the inner profile of the casing tube. [Figure 4A] 10 is a longitudinal cross section through a rotor shaft according to an embodiment having additional coolant guide tubes. [Figure 4B] 1 is a longitudinal cross section through a rotor shaft according to one embodiment without additional coolant guide tubes. [Figure 4C]10 is a longitudinal section through a rotor shaft according to a further embodiment having additional coolant guide tubes. [Figure 5A] 1 shows a longitudinal section of a rotor shaft with coolant guide tubes and additional cooling ducts in the elements for electromagnetic force transmission; [Figure 5B] 4 is a longitudinal section of a rotor shaft without additional coolant guide tubes and additional cooling ducts in the elements for electromagnetic force transmission. [Figure 6] 1 is an electric machine according to a possible embodiment having a rotor and a stator as described herein; [Figure 7A] FIG. 1 is a side view of a rotor shaft component according to an exemplary embodiment of the present disclosure having a press-fit coolant distribution element / end plug, a tapered casing tube, and a coolant distribution element disposed within the tapered portion. [Figure 7B] FIG. 10 is a side view of a rotor shaft component having a welded coolant distribution element / end plug, a tapered casing tube, and a coolant distribution element disposed within the tapered portion according to one embodiment of the present disclosure. [Figure 7C] FIG. 7C is a side view of the assembled rotor shaft of FIG. 7A or FIG. 7B. [Figure 8] FIG. 7C is a side view of the first end plug of FIG. 7B. [Figure 9A] FIG. 10 is a side view of a tapered casing tube according to one embodiment having an inner profile with helically extending longitudinal grooves. [Figure 9B] FIG. 9B is an inside view of the tapered casing tube of FIG. 9A. [Figure 9C] 1 is a plan view of a casing tube according to one embodiment having an inner profile with helically extending longitudinal grooves; FIG. [Figure 10A] FIG. 10 is a cross-sectional view of a rotor shaft according to a possible embodiment having a contoured inner tube with a cross-section having three-fold rotational symmetry, in which the ridges of the inner tube's profile engage with some of the depressions of the inner profile of a casing tube with a cross-section having three-fold rotational symmetry. [Figure 10B]10 is a cross-sectional view of a rotor shaft according to a possible embodiment having hexagonal inner and outer tubes, the inner profile of which is configured to abut its ridges against the outside of the inner tube. [Figure 11] FIG. 10 is a side view of a rotor shaft component having a press-fit end plug, an inner tube having an outer contour, and a tapered outer tube without an inner contour according to one embodiment of the present disclosure. [Figure 12A] 1 is a longitudinal cross section through a rotor shaft according to one embodiment having tapered casing tubes and additional coolant guide tubes. [Figure 12B] 1 is a longitudinal cross section through a rotor shaft according to one embodiment with tapered casing tubes and no additional coolant guide tubes. [Figure 12C] 10 is a longitudinal section through a rotor shaft according to a further embodiment, having tapered casing tubes and additional coolant guide tubes. [Figure 13A] 1 is a longitudinal section of a rotor shaft with tapered casing tubes, coolant guide tubes and additional cooling ducts within the elements for electromagnetic power transmission. [Figure 13B] 4 is a longitudinal section of a rotor shaft with a tapered casing tube without additional coolant guide tubes and additional cooling ducts in the elements for electromagnetic power transmission. DETAILED DESCRIPTION OF THE INVENTION

[0037] 5. Detailed Description of the Embodiments Some exemplary embodiments of the present disclosure will be described below using the example of some exemplary rotor shafts for electric machines. Various combinations of features will be described herein with reference to the illustrated embodiments. Of course, not all features of the described embodiments need to be present to realize the present invention. Furthermore, the embodiments can be modified by combining specific features of one embodiment with one or more features of another embodiment (where this is technically compatible and advantageous) without departing from the disclosure and the scope of protection of the present invention as defined by the claims.

[0038] FIG. 1A shows a side view of components of a rotor shaft 1 according to a possible embodiment of the present disclosure. The rotor shaft 1 includes a casing tube 10 having a wall thickness ranging from 2.00 mm to 10.00 mm, for example, and a periodic inner profile 11 having a plurality of longitudinal grooves extending axially in the illustrated embodiment. The illustrated embodiment further includes an inner tube 20 having a wall thickness ranging from 0.5 mm to 5.00 mm, for example, a first end plug or coolant distribution element 30, a second end plug or coolant distribution element 40, and a coolant 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 coolant distribution structure 42 for the inflow of the coolant, and the first end plug 30 has coolant distribution structures 32, 33 for the outflow of the coolant. 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 driven wheel, a propeller, a transmission, etc. Other corresponding embodiments can, for example, have other inner contours 11 of the casing tube 10 and outer contours 31, 41 of the end plugs 30, 40, other coolant distribution structures 32, 33, 42 and / or other torque transmission elements 34, and / or can omit the use of the coolant guide tube 50.

[0039] 1B shows a side view of a rotor shaft 1 according to a possible embodiment assembled from the components described in FIG. 1A. The casing tube 10 is connected to a first end plug 30 and a second end plug 40 in a form-fit and press-fit manner. The first end plug 30 may have a torque transmission element 34. The connection between the casing tube 10 and the end plugs 30, 40 may be achieved, for example, by pressing the end plugs 30, 40 onto the casing tube 10, with the first end plug 30 and the second end plug 40 each engaging with a portion of multiple longitudinal grooves in the inner contour 11 of the casing tube 10, for example, such that the ridges of the outer contours 31, 41 engage with the inner contour 11. The inner tube 20 and the coolant guide tube 50, not visible in this view, are positioned coaxially within the casing tube 10 and at least partially between the first end plug 30 and the second end plug 40.

[0040] 2A shows a side view of a first end plug or coolant distribution element 30 according to a possible embodiment, the first end plug 30 having an outer contour 31, coolant distribution structures 32, 33, and torque transmission elements 34. In this exemplary embodiment, the outer contour 31 of the first end plug 30 has longitudinal ridges extending axially and having different axial lengths so that coolant can be introduced from the cooling ducts formed by the inner tube 20 and the longitudinal grooves to the coolant distribution structures 32, 33. The end plug 30 further has a fitting 36 for a rotary bearing (e.g., a rolling bearing) of the electric machine.

[0041] 2B shows a further view of the first end plug 30 according to a possible embodiment, with a viewing direction along the axial or longitudinal direction of the rotor shaft. The exemplary embodiment has an outer contour 31 of periodically repeating ridges around the circumference of the first end plug 30, in each case every other ridge being lower to allow fluid connection between the cooling ducts and the cooling medium distribution structures 32, 33.

[0042] 2C shows a side view of a possible embodiment of a second end plug 40, which also has an outer contour 41 and a coolant distribution structure 42. In this exemplary embodiment, the outer contour 41 of the second end plug 40 has axial longitudinal ridges with different axial lengths, similar to those described above for the first end plug 30. The end plug 40 further includes a mating portion 46 for a rotary bearing (e.g., a rolling bearing) of the electric machine.

[0043] 2D shows a further view of the second end plug 40 according to a possible embodiment, with a viewing direction along the axial direction. The exemplary embodiment has an outer contour 41 of periodically repeating ridges around the circumference of the second end plug 40, in each case the ridges being lower every other ridge to allow fluid connection between the cooling ducts and the cooling medium distribution structure 42.

[0044] 3A shows a cross-section of a rotor shaft 1 according to a possible embodiment, having an unprofiled circular inner tube 20 in the assembled state. In this exemplary embodiment, the casing tube 10 has a series of axially extending ridges and depressions that are repeated periodically around the circumference of the casing tube 10 and form the inner profile 11 of the casing tube 10. The ridges of the inner profile 11 are in contact with the outer surface of the inner tube 20. The free space within the longitudinal grooves or depressions of the inner profile 11 defined by the casing tube 10 and the inner tube 20 defines axially extending cooling ducts for receiving a cooling medium, such as cooling water, oil, or cooled fuel, which can then be supplied to a plant for energy conversion.

[0045] 3B shows a cross-sectional view of a rotor shaft 1 according to a possible embodiment having a profiled inner tube 20, where the ridges of the profile of the inner tube 20 engage with some of the depressions or grooves of the inner profile 11 of the casing tube 10. In the illustrated exemplary embodiment, the ridges of the profile of the inner tube 20 are formed such that they engage in a form-fitting manner with every other depression of the inner profile 11 of the casing tube 10, and thus the cooling ducts extend into every other longitudinal groove of the inner profile 11 of the casing tube 10.

[0046] 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 no profile at all (see, for example, Figure 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.

[0047] FIG. 4A illustrates a longitudinal cross section of a rotor shaft 1 according to one embodiment, in which a first end plug or cooling medium distribution element 30 has a cooling medium inlet section 35 and an outlet section 33. The contours of the cooling medium within the rotor shaft 1 are indicated schematically by arrows. In the exemplary embodiment illustrated in FIG. 4A, the first end plug 30 has an inlet section 35 through which the cooling medium is guided within the first end plug 30 in the direction of the arrow. The cooling medium passes through a cooling medium guide tube 50, which, in the illustrated possible embodiment, connects the inlet section 35 of the first end plug 30 to a cooling medium distribution structure 42 of a second end plug 40 so as to enter the cooling medium distribution structure 42 along the illustrated arrow. The cooling medium distribution structure 42 guides the cooling medium in at least partially radially extending ducts into axially extending cooling ducts defined in the free space between the casing tube 10 and the inner tube 20. In the illustrated exemplary embodiment, the cooling ducts guide the cooling medium from the second end plug 40 back toward the first end plug 30. The cooling medium distribution structure 32 of the first end plug 30 is connected to the cooling ducts and can guide the cooling medium into the interior of the first end plug 30. A second portion of the cooling medium distribution structure 33 of the first end plug 30 represents the cooling medium outlet. Thus, in this possible embodiment, the cooling medium inlet and outlet are located in the same end plug 30, which in some embodiments also has a torque transmission element.

[0048] FIG. 4B shows a longitudinal cross section of a rotor shaft 1 according to another possible embodiment, in which a first end plug 30 has a cooling medium inlet 35 connected to a cooling medium distribution structure 32, and a second end plug 40 has a cooling medium outlet 45 connected to the cooling medium distribution structure 42 of the second end plug 40. The contours of the cooling medium within the rotor shaft 1 are again indicated schematically by arrows. In the illustrated embodiment, the cooling medium passes through the inlet 35 into the interior of the first end plug 30 in the direction of the arrows. The inlet 35 is connected to the cooling medium distribution structure 32 of the first end plug 30, which guides the cooling medium in the at least partially radially extending duct into an axially extending cooling duct defined in the free space between the casing tube 10 and the inner tube 20. The cooling duct guides the cooling medium from the first end plug 30 to the second end plug 40, where it can be guided from the cooling medium distribution structure 42 of the second end plug 40 to the outlet 45. In this possible embodiment, the inlet and outlet of the cooling medium are therefore arranged in different end plugs.

[0049] FIG. 4C shows a longitudinal cross section of a rotor shaft 1 according to one embodiment, in which the second end plug 40 has a cooling medium inlet 46 and outlet 43. The contours of the cooling medium within the rotor shaft 1 are again indicated schematically by arrows. In the illustrated embodiment, the cooling medium is guided into the interior of the second end plug 40 via the inlet 46 in the direction of the arrows. The cooling medium passes through a cooling medium guide tube 50, which in the illustrated embodiment connects the inlet 46 of the second end plug 40 to the cooling medium distribution structure 32 of the first end plug 30 along the illustrated arrows to enter 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 ducts to axially extending cooling ducts defined in the free space between the casing tube 10 and the inner tube 20. In the illustrated embodiment, the cooling ducts guide the cooling medium from the first end plug 30 back toward the second end plug 40. The coolant distribution structure 42 of the second end plug 40 can also be connected to an axial cooling duct to guide the coolant into the interior of the second end plug 40. The coolant distribution structure 42 of the second end plug 40 guides the coolant to the outlet 43, through which the coolant leaves the second end plug 40. Thus, in this possible embodiment, the coolant inlet and outlet are arranged in the second end plug 40. This has the advantage, among other things, that the first end plug 30 with the torque transmission element 34 does not require connections for the coolant, which can result, among other things, in improved mechanical properties of the first end plug 30 and space savings for electric drive systems (e.g., direct drive for the wheels of a car or drive for a propeller of an aircraft) when an actively cooled rotor shaft 1 is used.

[0050] FIG. 5A shows a longitudinal cross section of an embodiment of a rotor shaft 1, in which a first end plug 30 has a cooling medium inlet 35 and outlet 33 and an electromagnetic power transmission element 60 (e.g., a laminated rotor core with permanent magnets or rotor windings) rotationally fixedly connected, preferably by press-fit, to a portion of the outer surface of the casing tube 10. The contours of the cooling medium within the rotor shaft 1 and the electromagnetic power transmission element 60 are again indicated diagrammatically by arrows. The rotor shaft 1 represents the rotor 2 of a rotating electric machine 3, together with the electromagnetic power transmission element 60, which may have a dedicated cooling duct 61. In the possible embodiment shown in FIG. 5A, the cooling medium can enter the first end plug 30 via the inlet 35. The cooling medium passes through a 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 along the arrows. The cooling medium distribution structure 42 guides the cooling medium in the at least partially radially extending ducts into axially extending cooling ducts defined in the free space between the casing tube 10 and the inner tube 20 and into the cooling ducts 61 of the electromagnetic power transmission element 60. The cooling medium can pass through the cooling ducts from the second end plug 40 to the first end plug 30, where it can be received by the cooling medium distribution structure 32 of the first end plug 30 and guided to the outlet 33. In this possible embodiment, the inlet and outlet of the cooling medium are therefore arranged in the same end plug.

[0051] FIG. 5B shows a longitudinal cross section of an embodiment of the rotor shaft 1, in which the first end plug 30 has a cooling medium inlet 35 connected to the cooling medium distribution structure 32 of the first end plug 30, and the second end plug 40 has a cooling medium outlet 45 connected to the cooling medium distribution structure 42 and an electromagnetic power transmission element 60 rotationally fixedly connected, preferably by press-fit, to a portion of the outer surface of the casing tube 10. The contours of the cooling medium within the rotor shaft and the electromagnetic power transmission element are indicated diagrammatically by arrows. The rotor shaft 1 represents the rotor 2, together with the electromagnetic power transmission element 60, which may have its own cooling duct 61. The cooling medium can pass from the first end plug 30 to the second end plug 40 via the cooling duct, where it can be received by the cooling medium distribution structure 42 of the second end plug 30 and guided to the outlet 45. Thus, in this possible embodiment, the cooling medium inlet and outlet are located in different end plugs. An element 60 for electromagnetic power transmission with dedicated cooling ducts 61 can also be combined with the embodiment of FIG. 4C.

[0052] The embodiments shown in Figures 4A, 4B, 4C, 5A, and 5B are possible examples of the present disclosure. Additional possible embodiments can have, for example, a coolant inlet and outlet at second end plug 40, or an inlet at second end plug 40 and an outlet at first end plug 30. Embodiments with multiple inlets and / or multiple outlets, and / or coolant lines running opposite the direction of the arrows shown, as well as other embodiments not mentioned, are also possible.

[0053] 6 shows an electric machine 3 according to a possible embodiment, having a rotor 2 and a stator 4. The rotor 2 comprises a rotor shaft 1 and an element 60 for transmitting electromagnetic forces according to one or another of the exemplary embodiments described above, which is rotationally fixedly connected to the rotor shaft 1, preferably in a press-fit manner, and is rotatable relative to the stator 4 (for example by means of two rolling bearings), and has a torque transmission element 34. In a possible embodiment, one of the end plugs can be used for torque transmission by form-fitting or press-fit connection to the casing tube 10 or to the inner contour 11 of the casing tube 10.

[0054] FIG. 7A shows a side view of components of a possible embodiment of a rotor shaft 1 having a tapered casing tube 10 with an inner contour 11, a contoured inner tube 20, and coolant guide tubes 50. In the possible embodiment shown, the casing tube 10 is tapered at one end, resulting in a smaller radius at one end than the remainder of the length of the casing tube 10. Additionally, the rotor shaft 1 has a first end plug 30 (i.e., a first coolant distribution element) and a second coolant distribution element 40. The first end plug 30 can have an outer contour 31, and the second coolant distribution element 40 can have an outer contour 41. In the exemplary embodiment shown, the second coolant distribution element 40 has a coolant distribution structure 42 for the coolant, and the first end plug 30 has coolant distribution structures 32, 33 for the inflow and outflow of the coolant (see FIG. 12A).

[0055] In the illustrated embodiment, the first end plug 30 further includes a torque transmission element 34, through which the rotor shaft 1 can be connected, for example, to a driven wheel, a propeller, a transmission, etc. The tapered portion 12 can be configured so that a second cooling medium distribution element 40 can be at least partially received within the tapered portion 12 of the casing tube 10. The first end plug 30 in the illustrated embodiment is configured to be pressed into the casing tube 10. As with the other embodiments described herein, each individual component can be constructed of, for example, metal, non-ferrous metal, steel, ceramic, plastic, natural material, and / or combinations thereof. The different components can be constructed of different and / or the same materials to optimize their respective qualities, for example, with respect to component requirements, labor costs, and / or material costs. The formed end of the casing tube, in this exemplary case the tapered portion 12, can not only replace a portion of the second end plug 40 as shown in FIG. 7A compared to FIG. 1A.

[0056] Other possible embodiments of the casing tube 10 can have one or both formed ends that perform the specific function of at least one of the end plugs 30, 40, such that each end plug 30, 40 is an integral part of the casing tube 10 and the corresponding end plug 30, 40 does not exist as a separate component. The ends of the casing tube 10 can be different or identical.

[0057] 7B shows a side view of the components of a possible embodiment of a rotor shaft 1 having a tapered casing tube 10 with an inner contour 11, a contoured inner tube 20, and coolant guide tubes 50. Compared to the embodiment of FIG. 7A, the outer contour of the end plug 30 is significantly reduced, so that the rotationally fixed connection between the end plug 30 and the casing tube 10 is not made by pressing, but by welding or another suitable integrally bonded connection technique.

[0058] FIG. 7C shows a side view of a rotor shaft 1 according to a possible embodiment assembled from the components described in FIGS. 7A and 7B , in which the tapered casing tube 10 is rotationally fixedly connected to a first end plug or cooling medium distribution element 30, which may have a torque transmission element 34. The second cooling medium distribution element 40 is not visible in FIG. 7C because it is located inside the tapered portion 12 of the casing tube. The connection between the casing tube 10 and the end plug 30 can be achieved, for example, by pressing and / or welding, and the first end plug 30 engages with some of the multiple longitudinal grooves in the inner profile 11 of the casing tube 10, for example, so that the ridges of the outer profile 31 engage with the ridges of the inner profile 11. The inner tube 20 and the cooling medium guide tube 50 are not visible in this view but are located inside the casing tube 10 coaxially with the casing tube 10 and at least partially between the first end plug 30 and the second cooling medium distribution element 40 (also not visible). Since the rotor shaft engages the 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 any strong mechanical loads and can therefore, like the inner tube and the coolant guide tube, also be manufactured from an advantageous, lightweight material such as a suitable plastic (e.g. PEEK) or aluminum.

[0059] Figure 8 shows a side view of the first end plug 30 according to the exemplary embodiment shown in Figure 7B. The illustrated exemplary first end plug 30 has a significantly reduced outer profile compared to the embodiment of Figure 2A, since the connection of the first end plug 30 to the casing tube 10 is made by welding. Furthermore, the first end plug 30 has coolant distribution structures 32, 33, a fitting 36 for a rotary bearing of the electric machine, and a torque transmission element 34.

[0060] 9A shows a possible embodiment of a casing tube 10 having an inner profile 11 and a tapered portion 12 at one end of the casing tube 10. In this case, the inner profile is designed such that the longitudinal grooves defined by the inner profile extend helically along the longitudinal axis of the casing tube 10. The angle at which the longitudinal grooves are oriented relative to the axial direction of the casing tube 10 can be any desired angle that effectively provides longitudinal transport of the cooling medium.

[0061] FIG. 9B shows a side view of the casing tube 10 cut open with the tapered portion 12 of FIG. 9A, in which the helical profile of the longitudinal grooves of the inner profile 11 is visible.

[0062] 9C shows a possible embodiment of a casing tube 10 having an inner contour 11. In this case, the inner contour is designed such that the longitudinal grooves defined by the inner contour extend helically along the longitudinal axis of the casing tube 10, thus realizing an alternative and effective longitudinal transport of the cooling medium. The angle at which the longitudinal grooves are oriented relative to the axial direction of the casing tube 10 can be any other desired angle at which an effective longitudinal transport of the cooling medium is achieved.

[0063] 10A shows a cross section through the casing tube 10 and inner tube 20 of a rotor shaft 1 according to a possible embodiment, with the inner tube 20 contoured with a cross section of three-fold rotational symmetry. The ridges of the contour of the inner tube 20 are configured to engage with some of the recesses of the inner contour 11 of the casing tube 10. The casing tube 10 is also designed with a cross section of three-fold rotational symmetry. The deviation from a circular cross section prevents relative rotation between the inner tube 20 and the casing tube 10.

[0064] 10B shows a cross-section through the casing tube 10 and inner tube 20 of a rotor shaft 1 according to a possible embodiment having hexagonal inner and outer tubes, the inner contour of which is configured to abut its ridges against the outside of the inner tube. The exemplary inner contour 11 of the casing tube has a contour similar to the curvature of the casing tube 10's interior, generally hexagonal shape. In the illustrated embodiment, every third ridge of the inner contour 11 of the casing tube 10 is configured to abut a corner of the hexagonal inner tube 20. Furthermore, each of the ridges that abut a corner of the inner tube 20 has a central recess to accommodate the corner and thus prevent relative rotation between the inner tube 20 and the casing tube 10.

[0065] FIG. 11 shows a side view of components of a rotor shaft 1 according to a possible embodiment of the present disclosure. The rotor shaft comprises a non-contoured casing tube 10 having a smooth interior and exterior, e.g., a wall thickness in the range of 2.00 mm to 10.00 mm, with a tapered portion 12 at one end of the casing tube 10. The illustrated embodiment further comprises a contoured inner tube 20 having a wall thickness of e.g., 0.5 mm to 5.00 mm, a first end plug 30, a second coolant distribution element 40, and a coolant guide tube 50. The first end plug 30 can have an outer contour 31, and the second coolant distribution element 40 can have an outer contour 41.

[0066] In the illustrated embodiment, the second coolant distribution element 40 has a coolant distribution structure 42 for the coolant, and the first end plug 30 has coolant distribution structures 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 to, for example, a driven wheel, a propeller, a transmission, etc. Other corresponding embodiments can, for example, have other outer contours 31, 41 of the end plugs 30, 40, other coolant distribution structures 32, 33, 42, and / or other torque transmission elements 34, and / or can omit the use of the coolant guide tube 50. At least one of the end plugs 30, 40 can be connected to the casing tube 10, the inner tube 20, and / or the coolant guide tube 50, for example, by welding. The tapered portion 12 can be configured such that the second coolant distribution element 40 can be at least partially received within the tapered portion 12 of the casing tube 10. The first end plug 30 in the illustrated embodiment is configured to be welded and / or pressed onto the casing tube 10 to create a rotationally fixed connection.

[0067] FIG. 12A shows a longitudinal cross section of a rotor shaft 1 according to one embodiment, in which a first end plug or coolant distribution element 30 has a coolant inlet section 35 and an outlet section 33. The contours of the coolant within the rotor shaft 1 are indicated schematically by arrows. In the illustrated embodiment, a first end plug 30 is present, similar to FIG. 4A. In the exemplary embodiment shown in FIG. 12A, the first end plug 30 has an inlet section 35 through which the coolant is guided inside the first end plug 30 in the direction of the arrow. The coolant passes through a coolant guide tube 50, which in the illustrated possible embodiment connects the inlet section 35 of the first end plug 30 to a coolant distribution structure 42 (also referred to herein as a coolant distribution element) of a second end plug 40, such that the coolant enters the coolant distribution structure 42 along the illustrated arrow. The second coolant distribution element 40 is disposed inside the tapered section 12 of the casing tube 10, which is adapted to the rotary bearing of the electric machine.

[0068] The cooling medium distribution structure 42 guides the cooling medium in the at least partially radially extending duct to an axially extending cooling duct defined in the free space between the casing tube 10 and the inner tube 20. In the illustrated exemplary embodiment, the cooling duct guides the cooling medium from the second end plug 40 back toward the first end plug 30. The cooling medium distribution structure 32 of the first end plug 30 is connected to the cooling duct and can guide the cooling medium into the interior of the first end plug 30. The second portion of the cooling medium distribution structure 33 of the first end plug 30 represents the cooling medium outlet. Therefore, in this possible embodiment, the cooling medium inlet and outlet are located in the same end plug 30, which in some embodiments also has the torque transmission element 34.

[0069] FIG. 12B shows a longitudinal cross section of a rotor shaft 1 according to another possible embodiment, in which the first end plug 30 has a cooling medium inlet 35 connected to the cooling medium distribution structure 32, and the second end plug 40 has a cooling medium outlet 45 connected to the cooling medium distribution structure 42 of the second end plug 40. In the illustrated embodiment, similar to FIG. 4B, a first end plug 30 is present. The contours of the cooling medium within the rotor shaft 1 are again indicated schematically by arrows. In the illustrated embodiment, the cooling medium passes through the inlet 35 into the interior of the first end plug 30 in the direction of the arrows. The inlet 35 is connected to the cooling medium distribution structure 32 of the first end plug 30, which guides the cooling medium in an at least partially radially extending duct into an axially extending cooling duct defined in the free space between the casing tube 10 and the inner tube 20. The cooling ducts guide the cooling medium from the first end plug 30 to the second end plug 40, where it can be guided from the cooling medium distribution structure 42 of the second end plug 40 to the outlet 45. In this possible embodiment, the inlet and outlet of the cooling medium are therefore arranged in different end plugs. The second cooling medium distribution element 40 is arranged inside the tapered section 12 of the casing tube 10, which tapered section 12 is adapted to the rotary bearing of the electric machine.

[0070] FIG. 12C shows a longitudinal cross section of a rotor shaft 1 according to one embodiment, in which the second end plug 40 has a cooling medium inlet 46 and outlet 43. The contours of the cooling medium within the rotor shaft 1 are again indicated schematically by arrows. In the illustrated embodiment, the cooling medium is guided into the interior of the second end plug 40 via the inlet 46 in the direction of the arrows. The cooling medium passes through a cooling medium guide tube 50, which in the illustrated embodiment connects the inlet 46 of the second end plug 40 to the cooling medium distribution structure 32 of the first end plug 30 along the illustrated arrows to enter 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 ducts to axially extending cooling ducts defined in the free space between the casing tube 10 and the inner tube 20. In the illustrated embodiment, the cooling ducts guide the cooling medium from the first end plug 30 back toward the second end plug 40 (also described herein as the cooling medium distribution element). The cooling medium distribution structure 42 of the second end plug 40 can also be connected to the axial cooling ducts and guide the cooling medium into the interior of the second end plug 40. The second cooling medium distribution element 40 is arranged inside the tapered portion 12 of the casing tube 10, which tapered portion 12 fits into the rotary bearing of the electric machine. The cooling medium distribution structure 42 of the second end plug 40 guides the cooling medium to the outlet portion 43, through which the cooling medium leaves the second end plug 40. Thus, in this possible embodiment, the inlet and outlet portions of the cooling medium are arranged in the second end plug 40. This has the advantage, inter alia, that the first end plug 30 with the torque transmission element 34 does not require a connection for a cooling medium, which can result, inter alia, in improved mechanical properties of the first end plug 30 and space savings in electric drive systems (e.g., direct drive for the wheels of a car or drive for a propeller of an aircraft), and where an actively cooled rotor shaft 1 is used.

[0071] FIG. 13A shows a longitudinal cross section of an embodiment of a rotor shaft 1, in which a first end plug 30 has a cooling medium inlet 35 and outlet 33 and an electromagnetic power transmission element 60 rotationally fixedly connected, preferably by press-fit, to a portion of the outer surface of the casing tube 10. The contours of the cooling medium within the rotor shaft 1 and the electromagnetic power transmission element 60 are again indicated diagrammatically by arrows. The rotor shaft 1 represents the rotor 2 of a rotating electric machine 3, together with the electromagnetic power transmission element 60, which may have its own cooling duct 61. In the possible embodiment shown in FIG. 13A, the cooling medium can enter the first end plug 30 via the inlet 35. The cooling medium passes through a cooling medium guide tube 50, which, in the illustrated possible embodiment, connects the inlet 35 of the first end plug 30 to the cooling medium distribution structure 42 of the second end plug 40 along the illustrated arrows and enters the cooling medium distribution structure 42 of the second end plug 40. The second cooling medium distribution element 40 is arranged inside the tapered section 12 of the casing tube 10, which is adapted to the rotary bearing of the electric machine. The cooling medium distribution structure 42 guides the cooling medium in the at least partially radially extending duct into an axially extending cooling duct defined in the free space between the casing tube 10 and the inner tube 20 and into the cooling duct 61 of the element for electromagnetic power transmission 60. The cooling medium can pass through the cooling duct from the second end plug 40 to the first end plug 30, where it can be received by the cooling medium distribution structure 32 of the first end plug 30 and guided to the outlet 33. Therefore, in this possible embodiment, the inlet and outlet of the cooling medium are arranged in the same end plug.

[0072] FIG. 13B shows a longitudinal cross section of an embodiment of the rotor shaft 1, in which the first end plug 30 has a cooling medium inlet 35 connected to the cooling medium distribution structure 32 of the first end plug 30, and the second end plug 40 has a cooling medium outlet 45 connected to the cooling medium distribution structure 42 and an electromagnetic power transmission element 60 rotationally fixedly connected, preferably by press-fit, to a portion of the outer surface of the casing tube 10. The contours of the cooling medium within the rotor shaft and the electromagnetic power transmission element are indicated diagrammatically by arrows. The rotor shaft 1 represents the rotor 2, together with the electromagnetic power transmission element 60, which may have its own cooling duct 61. The cooling medium can pass through all the cooling ducts from the first end plug 30 to the second end plug 40, where it can be received by the cooling medium distribution structure 42 of the second end plug 30 and guided to the outlet 45. Therefore, in this possible embodiment, the cooling medium inlet and outlet are located in different end plugs. The second cooling medium distribution element 40 is arranged inside the tapered portion 12 of the casing tube 10, which tapered portion 12 fits over the rotary bearing of the electric machine.

[0073] 12A-13B, the first end plug 30 has the same structure as in FIGS. 4A-5C and is connected to the casing tube 10 by pressing, but the embodiments differ in the design of the coolant distribution element 40. This can be realized as an end plug 40 (FIGS. 4A-5C) or as a coolant distribution element 40 that is at least partially received by the tapered portion 12 of the casing tube 10.

[0074] Further Exemplary Embodiments Further possible embodiments are described below.

[0075] 1. A rotor shaft for a rotor of an electric machine, comprising: a casing tube having an inner profile with a plurality of longitudinal grooves; an inner tube disposed inside the casing tube; first and second end plugs, each connected to one end of the casing tube by form-fitting and press-fitting or form-fitting and integral coupling by engaging portions of the plurality of longitudinal grooves; The inner contour of the casing tube and the outside of the inner tube define a plurality of cooling ducts through which a cooling medium can flow along the casing tube, the rotor shaft.

[0076] 2. A rotor shaft as described in embodiment 1, wherein at least one of the two end plugs has a torque transmission element.

[0077] 3. The inner contour of the casing tube along the circumference of the casing tube has periodically repeated ridges and depressions; 3. A rotor shaft according to any one of embodiments 1 or 2.

[0078] 4. The inner tube engages with a portion of the plurality of longitudinal grooves; The rotor shaft according to any one of the first to third embodiments.

[0079] 5. A rotor shaft as described in embodiment 4, wherein the inner tube has a cross-section with periodically repeating ridges and depressions along its circumference, the ridges engaging with portions of longitudinal grooves in the inner contour of the casing tube.

[0080] 6. The casing tube has a wall thickness in the range of 2.00 mm to 10.00 mm, and / or The inner tube has a wall thickness ranging from 0.5 mm to 5.00 mm. The rotor shaft according to any one of the first to fifth embodiments.

[0081] 7. 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 7. The rotor shaft according to any one of the preceding embodiments 1 to 6, 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.

[0082] 8. One or both of the end plugs have an outer contour that engages the inner contour of the casing tube, and / or The end plugs are pressed against the casing tube, and / or The end plugs are welded to the casing tube. The rotor shaft according to any one of the first to seventh embodiments.

[0083] 9. The end plugs each have a cooling medium distribution structure connected to one of the cooling ducts defined through the inner contour of the casing tube and the outside of the inner tube; The rotor shaft according to any one of the first to eighth embodiments.

[0084] 10. One end plug has an inlet for the cooling medium connected to the cooling medium distribution structure, and the other end plug has an outlet for the cooling medium connected to the cooling medium distribution structure; A rotor shaft according to embodiment 9.

[0085] 11. Further comprising a cooling medium guide tube disposed within the inner tube and connecting the two end plugs to each other so that the cooling medium can flow from one end plug to the other end plug through the cooling medium guide tube; One of the end plugs has an inlet and an outlet for the cooling medium, the outlet being connected to the cooling medium distribution structure and the inlet being connected to the cooling medium guide tube. A rotor shaft according to embodiment 9.

[0086] 12. A rotor shaft according to embodiment 2 and embodiment 10 or embodiment 11, wherein the end plug having an inlet for a cooling medium also has a torque transmission element.

[0087] 13. A rotor for an electric machine, comprising: The rotor shaft according to any one of the first to twelfth embodiments, an element for transmitting electromagnetic force, which is rotationally and fixedly connected to a portion of the outer surface of the casing tube, preferably by press-fitting; Prepare the rotor.

[0088] 14. A rotor as described in embodiment 13, comprising a rotor shaft as described in any one of embodiments 9 to 12, wherein the element for electromagnetic force transmission has at least one cooling duct connected to the cooling medium distribution structure of the two end plugs.

[0089] 15. An electric machine, a stator; A rotor according to any one of the preceding embodiments 13 or 14; and An electric machine comprising:

Claims

1. A rotor shaft (1) for a rotor of an electric machine (3), comprising: a casing tube (10); an inner tube (20) disposed inside the casing tube; two cooling medium distribution elements (30, 40) each disposed at one end of the rotor shaft; the casing tube has an inner contour (11) with a plurality of longitudinal grooves, and / or the inner tube has an outer contour with a plurality of longitudinal grooves, The inner contour of the casing tube and / or the outer contour of the inner tube define a plurality of cooling ducts through which a cooling medium can flow from one cooling medium distribution element to another along the rotor shaft.

2. The rotor shaft of claim 1 , wherein at least one of the two coolant distribution elements comprises a torque transmission element (34).

3. the inner contour of the casing tube along its circumference and / or the outer contour of the inner tube along its circumference has periodically repeating ridges and depressions; The rotor shaft according to claim 1 or 2.

4. the inner tube engages with some of the longitudinal grooves of the inner contour of the casing tube; The rotor shaft according to claim 1 or 2.

5. 5. The rotor shaft of claim 4, wherein the inner tube has a cross section with periodically repeating ridges and depressions around its circumference, the ridges engaging the portions of the longitudinal grooves of the inner contour of the casing tube.

6. the casing tube has a wall thickness in the range of 2.00 mm to 10.00 mm; and / or the inner tube having a wall thickness in the range of 0.5 mm to 5.00 mm; The rotor shaft according to claim 1 or 2.

7. the inner profile of the casing tube has a profile depth in the range of 1.00 mm to 6.00 mm; and / or A rotor shaft according to claim 1 or 2, wherein the inner tube has a profile depth in the range of 0.5 mm to 4.00 mm.

8. 3. The rotor shaft according to claim 1, wherein each of the cooling medium distribution elements is connected to one end of the casing tube by integral bonding through form-fitting and press-fitting or form-fitting and engaging with a portion of the plurality of longitudinal grooves.

9. one or both of the cooling medium distribution elements have an outer contour (31, 41) that engages with the inner contour of the casing tube; and / or one or both of the cooling medium distribution elements are pressed against the casing tube, and / or one or both of the cooling medium distribution elements are welded to the casing tube; The rotor shaft of claim 8 .

10. each of the cooling medium distribution elements has a cooling medium distribution structure (32, 33, 42) connected to one or more of the cooling ducts defined through the inner contour of the casing tube and / or the outer contour of the inner tube; The rotor shaft according to claim 1 or 2.

11. one of the cooling medium distribution elements has an inlet (35) for the cooling medium connected to the associated cooling medium distribution structure, and the other cooling medium distribution element has an outlet (45) for the cooling medium connected to the associated cooling medium distribution structure; The rotor shaft of claim 10.

12. a cooling medium guide tube (50) disposed within the inner tube and connecting the two cooling medium distribution elements to each other so that the cooling medium can flow from one cooling medium distribution element to the other cooling medium distribution element through the cooling medium guide tube; one of the cooling medium distribution elements has an inlet (35) and an outlet for the cooling medium, the outlet being connected to the associated cooling medium distribution structure and the inlet being connected to the cooling medium guide tube; The rotor shaft of claim 10.

13. 3. The rotor shaft of claim 2, wherein the cooling medium distribution element having an inlet for the cooling medium also comprises the torque transmission element.

14. 3. The rotor shaft of claim 2, wherein the coolant distribution element with the torque transmission element has no inlet or outlet for the coolant.

15. 3. A rotor shaft according to claim 1, wherein the casing tube has at least one end a fitting for a rotary bearing of the electric machine.

16. 16. A rotor shaft according to claim 15, wherein the casing tube has at least one end a tapered portion designed to receive the coolant distribution element in the interior of the casing tube and to serve as a running surface for the rotary bearings of the electric machine.

17. 1. A rotor for an electric machine, comprising: A rotor shaft according to claim 10; an element for transmitting electromagnetic force, rotationally fixedly connected to a portion of the outer surface of the casing tube; A rotor comprising:

18. A rotor as described in Claim 17, wherein the element for transmitting electromagnetic force has at least one cooling duct connected to the cooling medium distribution structure of the two cooling medium distribution elements.

19. 1. An electric machine comprising: a stator; A rotor according to claim 17; An electric machine comprising:

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