Rotor shaft for machine, connecting tube for rotor shaft, machine having rotor shaft of this type, and motor vehicle

Abstract

The invention relates to a rotor shaft (1) for a machine (2), in which an inner tube (5) is arranged coaxially in an outer tube (4), between which tubes an outer tube annulus (10) is formed. A first journal portion (14) of the journal (6) protrudes from the outer tube and a second journal portion (15) of the journal is coaxially arranged in the outer tube, axially spaced apart from the inner tube and sealingly connected to an inner wall (8) of the outer tube. According to the invention, the connecting pipe (3) rests on the outer circumferential side in a sealing manner on a journal inner wall (34) in the first journal portion and extends through the second journal portion, out of the second journal portion and into the inner pipe, and a journal annular space (39) communicating with the outer pipe annular space is formed between the connecting pipe outer wall (35) and the journal inner wall in the second journal portion. The invention also relates to the connecting pipe itself, to a machine and to a motor vehicle.

Description

Technical Field

[0001] The present invention relates to a rotor shaft for a machine, such as an electric traction machine for a motor vehicle. Furthermore, the present invention relates to a machine, in particular an electric traction machine, having such a rotor shaft. Furthermore, the present invention relates to a motor vehicle equipped with such a machine and a connecting pipe for the rotor shaft. Background Art

[0002] To ensure optimal operation of an electric drive or tractor, efficient cooling is essential during tractor operation. In particular, operating states in which the tractor's control system only provides a limited drive torque should be avoided to prevent undesirable overheating of tractor components. If this operating state occurs, the user of the tractor (especially the driver of a motor vehicle equipped with the tractor) can no longer utilize the tractor's usual full power. The user is surprised by the reduction / restriction of drive torque (known as fade) and must suddenly cope with reduced power. This can lead to problems in overtaking maneuvers, hill climbing, towing, and other situations. Therefore, there is a need to avoid these operating states as much as possible, which requires the most efficient cooling of the tractor. Machines whose rotor shafts are cooled internally by a cooling fluid are known from the prior art, for example from DE 949 611 B, DE 10 2012 217 361 A1, or DE 10 2014 204 133 A1. Summary of the Invention

[0003] The object of the present invention is to provide a solution for more efficient cooling of the rotor shaft of a machine, in particular of an electric machine.

[0004] This object is achieved by the subject matter of the independent claims. Further possible embodiments of the invention are disclosed in the dependent claims, the description, and the drawings. The features, advantages, and possible embodiments described within the description for one of the subject matter of an independent claim are to be regarded, across categories and across embodiments, at least in an analogous manner, as the features, advantages, and possible embodiments of the corresponding subject matter of the other independent claims, as well as any possible combination of the subject matter of the independent claims (if necessary in combination with one or more dependent claims).

[0005] According to the present invention, a rotor shaft for a machine is provided, the rotor shaft particularly comprising a connecting pipe (which may also be referred to as a coolant nozzle). The present invention also relates to the connecting pipe itself and a machine comprising the rotor shaft and, therefore, the connecting pipe. Furthermore, according to the present invention, a motor vehicle is provided, comprising the machine and, therefore, the rotor shaft with the connecting pipe. This means that, in a predetermined installation position of the connecting pipe, the connecting pipe forms a component of the rotor shaft, and, in a predetermined installation position of the rotor shaft, the rotor shaft forms a component of the machine. Once the machine is positioned in its predetermined installation position, it forms a component of the motor vehicle. The machine is particularly designed as an electric traction machine for a motor vehicle, meaning that the motor vehicle is designed as a vehicle capable of pure electric or hybrid drive.

[0006] The rotor shaft has an outer tube, which is configured, for example, to support the rotor assembly of an electric machine on its outer side in a rotationally fixed manner. Therefore, for this machine, the outer circumference of the outer tube and the rotor of the machine are preferably connected in a rotationally fixed manner. Within the hollow interior of the outer tube, the rotor shaft has an inner tube, with the outer and inner tubes being coaxially arranged. In other words, the longitudinal center axis of the outer tube coincides with the longitudinal center axis of the inner tube, or more specifically, with the longitudinal center axis of the rotor shaft. The inner tube is supported within the outer tube in such a manner that an outer tube annular space is formed between the outer tube inner wall of the outer tube and the inner tube outer wall of the inner tube. Furthermore, the inner tube has one or more inner tube wall openings, wherein each inner tube wall opening extends completely through the inner tube wall of the inner tube in a radial direction, parallel to the radius or obliquely relative to the radius. This allows the hollow interior of the inner tube to communicate with the hollow interior of the outer tube, or the hollow interior of the inner tube to communicate with the outer tube annular space. The inner tube, in particular, has a conical inner tube bottom that forms one of its ends and has axial grooves whose bases are radially spaced from the inner wall of the outer tube, forming an axial channel between the inner tube bottom and the inner wall of the outer tube. Furthermore, the inner tube is centrally supported in the outer tube by means of the inner tube bottom, such that the outer diameter of the inner tube at the inner tube bottom—which differs from the rest of the inner tube—is the same size as the inner diameter of the outer tube. Consequently, the hollow interior of the inner tube communicates with the annular space of the outer tube both via the inner tube wall opening and via the grooves or channels in the inner tube bottom.

[0007] Furthermore, the rotor shaft comprises a hollow journal having a first journal portion and a second journal portion that are fixedly connected to one another. In particular, these journal portions are integrally formed. The first journal portion projects from the outer tube and thereby forms the rotor shaft or the driven element of the machine. For example, a spur gear ring is mounted in a rotationally fixed manner on the first journal portion of the hollow journal. This spur gear ring is configured to mesh with a spur gear external to the machine, such as a drive spur gear of a transmission flanged to the machine. The second journal portion of the hollow journal is coaxially disposed within the outer tube, i.e., within its hollow interior, and spaced apart from the inner tube along the longitudinal center axis of the rotor shaft. The second journal portion is sealed and rotationally fixedly connected to the inner wall of the outer tube. Thus, the outer tube annular space is delimited or defined by the outer tube inner wall, the inner tube outer wall, the annular end face of the second journal portion, and the inner tube bottom. At the second journal portion, the journal has one or more journal wall openings, wherein the respective journal wall openings extend completely through the journal wall of the journal in a radial direction, parallel to the radius, or obliquely relative to the radius. As a result, the hollow interior of the journal communicates with an output-side port of the outer tube (from which the first journal portion extends the outer tube).

[0008] The connecting tube of the rotor shaft is preferably constructed from plastic, for example as a plastic injection-molded part, and has a first connecting tube end that rests sealingly on the inner wall of the journal in the first journal portion on its outer circumference. Furthermore, the connecting tube extends through the second journal portion, wherein the connecting tube protrudes from the second journal portion. The connecting tube extends from the second journal portion into the inner tube, wherein a sealed connection exists between the inner tube and the connecting tube. A journal annular space is formed between the outer wall of the connecting tube and the inner wall of the journal in the second journal portion, wherein the journal annular space and the outer tube annular space communicate with or are connected to one another. The longitudinal center axis of the connecting tube and the longitudinal center axes of the outer tube, inner tube, and journal coincide with the longitudinal center axis of the rotor shaft.

[0009] This arrangement of the outer tube, inner tube, shaft neck, and connecting pipe creates a coolant path through which coolant, particularly oil, can flow. When a machine equipped with this rotor shaft is in operation, coolant is conveyed into the hollow interior of the shaft neck. To this end, the inlet line of the coolant module or oil module is fluidically coupled to the port of the shaft neck, i.e., to the hollow interior. For example, a hollow connecting pipe can be inserted into the port of the shaft neck, particularly pressed in, with a radial shaft seal provided between the inlet line and the shaft neck port. This radial shaft seal prevents coolant or oil from leaking at the coupling point between the inlet line and the shaft neck. For example, using a pump of the coolant module or oil module, oil is driven through the inlet line and thereby into the shaft neck and, further, into the rotor shaft. The oil flows through the shaft neck and subsequently into the connecting pipe, because the connecting pipe, with its first connecting pipe end, rests sealingly against the inner wall of the shaft neck in the first shaft neck portion, thereby preventing oil from leaking between the shaft neck and the connecting pipe. The oil continues to flow through the connecting tube and then flows out of it, thereby flowing into the inner tube, since the connecting tube opens into the inner tube. The oil then flows out of the inner tube through one or more inner tube wall openings and flows between the inner and outer tubes, that is, into the outer tube annular space. Furthermore, the oil flows from the inner tube into the outer tube annular space via grooves or channels provided in the bottom of the inner tube. The size and number of the corresponding inner tube wall openings or grooves are designed such that the majority of the oil in the inner tube flows through the one or more inner tube wall openings into the outer tube annular space, while a significantly smaller portion of the oil in the inner tube flows through the groove or grooves into the outer tube annular space. The end edge or bottom of the inner tube is spaced apart from the closure element of the rotor shaft, so that the oil flows out of the inner tube at the end edge, into the channel / groove, and from there into the outer tube annular space. In the outer tube annular space, the oil flows along the inner wall of the outer tube, where it absorbs heat generated during machine operation and then dissipates it. When the heated oil flows out of the outer tube annular space, it flows between the outer wall of the connecting tube and the inner wall of the journal, that is, into the journal annular space. From there, the oil flows through an opening in the journal wall or openings and ultimately out of the rotor shaft through the outlet port of the outer tube. The rotor shaft, in particular, leads via its outlet port into the transmission chamber of a transmission flanged to a machine. It is particularly provided that the coolant used to cool the machine is the same as the lubricant used to lubricate the transmission. In other words, the coolant circuit described herein can be part of a lubricant circuit comprising the machine and the transmission assembly.

[0010] The rotor shaft enables particularly efficient guidance of the oil or coolant flow to the rotor shaft or locations / components in the machine with particularly high cooling requirements. This ensures particularly efficient heat dissipation from these components and reliably protects the machine from overheating. This effectively prevents performance degradation of the machine, particularly when used as an electric traction machine in a motor vehicle.

[0011] In one possible development, the connecting pipe has a centering rib arrangement on its outer wall, through which a fluid can flow, along its longitudinal center axis. The connecting pipe is coaxially supported in the second journal section by means of this centering rib arrangement. The centering rib arrangement has three or more centering ribs, wherein each centering rib protrudes radially outward from the outer wall of the connecting pipe. In the rotor shaft, the outer wall of the connecting pipe and the inner wall of the journal are spaced apart at the height of the respective centering ribs, wherein the centering rib arrangement is arranged in the annular space of the journal or at least extends into the annular space of the journal. The centering ribs are evenly spaced apart along the circumference of the connecting pipe, so that, on the one hand, oil can flow between the centering ribs, and, on the other hand, the connecting pipe is particularly securely supported in a centered manner in the journal.

[0012] According to another possible embodiment, the connecting tube includes a docking flange on its outer wall, through which fluid can flow, along its longitudinal center axis. The connecting tube abuts against the annular end face of the second journal portion via this docking flange. This prevents the connecting tube from accidentally dislodging from its intended installation position during machine operation, for example, from excessively migrating into the journal. Furthermore, assembly of the rotor shaft is simplified. The docking flange comprises one or more docking elements, wherein each docking element rests directly against the annular end face of the second journal portion in the axial direction, i.e., along the longitudinal center axis of the rotor shaft. If the docking flange comprises two or more docking elements, they are evenly spaced apart along the outer circumference of the connecting tube. This allows oil to flow between the docking elements, while also providing particularly secure axial fixation of the connecting tube on the journal or its annular end face. The centering rib arrangement and / or the docking flange are preferably integral or monolithic with the connecting tube. This means that the centering rib arrangement and / or the docking flange are integrally formed during the initial forming, in particular injection molding, of the connecting tube.

[0013] According to another possible design, the connecting pipe has a first sealing ring seat at the first connecting pipe end. In this embodiment, the rotor shaft includes a first sealing ring, which is secured in the first sealing ring seat and thus between the inner wall of the shaft journal in the first shaft journal section and the outer wall of the connecting pipe. This ensures a particularly reliable fluid-tight connection between the connecting pipe and the hollow interior of the hollow shaft journal. Furthermore, the outlet port of the outer pipe and the shaft journal annular space are particularly reliably sealed from one another.

[0014] Another possible embodiment provides a connecting sleeve, by means of which the connecting pipe and the inner pipe are sealed together. The connecting sleeve surrounds or encloses the second connecting pipe end facing the inner pipe and the inner pipe end facing the connecting pipe on its outer circumference. The outer diameter of the connecting sleeve is smaller than the inner diameter of the outer pipe, so that the inner wall of the outer pipe and the connecting sleeve are radially spaced apart. In this way, the connecting sleeve is arranged in the annular space of the outer pipe and is surrounded by oil on the outside during operation. The connecting sleeve provides a particularly stable and reliable sealing connection between the connecting pipe and the inner pipe.

[0015] According to one possible development, the connecting tube has a second sealing ring seat at the second connecting tube end. In this regard, the rotor shaft has a second sealing ring, which is fixed in the second sealing ring seat. If the rotor shaft has a connecting sleeve as described above, it is particularly provided that the second sealing ring, which fits in the second sealing ring seat, is inserted between the outer wall of the connecting tube and the inner wall of the connecting sleeve. As a result, the fluid-tight connection achieved by the connecting sleeve between the connecting tube and the inner tube is particularly reliable and leak-tight. Due to the first and / or second sealing ring, the outer tube annular space and the shaft journal annular space are particularly reliably sealed relative to the corresponding hollow interiors of the shaft journal, connecting tube, and inner tube, which contributes to particularly efficient cooling of the rotor shaft.

[0016] If, as provided for in another possible embodiment, the outer tube inner wall has a surface-enhancing structure in the outer tube annular space, the rotor shaft can be cooled more effectively during machine operation. The surface-enhancing structure can, for example, comprise a plurality of annular grooves and / or annular grooves that are equidistant from one another or directly adjacent to one another. This creates a plurality of recesses, each extending radially from the outer tube inner wall toward the outer tube outer wall. In this embodiment, the surface-enhancing structure provides the outer tube annular space with a particularly large area of ​​the outer tube inner wall. As a result, a particularly large amount of oil can simultaneously flow directly along the outer tube material during machine operation. This allows a particularly high amount of heat to be removed from the outer tube at a given oil flow rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Further features of the invention can be derived from the claims, the drawings and the description of the drawings. The features and feature combinations mentioned above in the description and the features and feature combinations shown below in the description of the drawings and / or individually in the drawings can be used not only in the respectively indicated combination but also in other combinations or alone without departing from the scope of the invention.

[0018] In the attached figure:

[0019] Figure 1 shows a cross-sectional view of a machine having a rotor shaft with a connecting pipe,

[0020] Figure 2 A cross-sectional view showing the connecting pipe, and

[0021] Figure 3 A perspective view showing the connecting pipe. DETAILED DESCRIPTION

[0022] The following will collectively describe a rotor shaft 1 for a machine 2, a connecting pipe 3 of the rotor shaft 1, the machine 2, and a motor vehicle (not shown) having the machine 2. In the figures, identical and functionally identical elements are provided with the same reference numerals.

[0023] The connecting pipe 3 forms part of the rotor shaft 1, wherein the rotor shaft 1, in its intended installation position (as shown in the figures), forms part of the machine 2. The machine 2 is designed as an electric traction machine, wherein the motor vehicle has the traction machine 2 as a purely electrically or hybridly driven motor vehicle.

[0024] Figure 1 The cross-section of the machine 2 is shown. The rotor shaft 1 of the machine has a connecting tube 3, an outer tube 4, an inner tube 5, and a hollow journal 6. The outer tube 4 and the inner tube 5 are arranged coaxially with respect to the longitudinal center axis 7 of the rotor shaft 1. An outer tube annular space 10 is formed between the outer tube inner wall 8 and the inner tube outer wall 9. The outer tube annular space 10 communicates with the hollow interior 11 of the inner tube by virtue of the inner tube having inner tube wall openings 12, in this case two or more. These inner tube wall openings 12 are located in the vicinity of the conical inner tube bottom 13 of the inner tube 5, by which the inner tube 5 is centrally supported in the outer tube 4. At the conical inner tube bottom 13, which forms the first end of the inner tube 5, the outer diameter of the inner tube 5 is increased relative to the rest of the inner tube 5, specifically to the inner diameter of the outer tube 4, so that the inner tube 5 rests against the outer tube inner wall 8 via its inner tube bottom 13. Inner tube bottom 13 has axially arranged grooves 13a along its outer circumference, with the bases of these grooves radially spaced apart from outer tube inner wall 8. Thus, grooves 13a and outer tube inner wall 8 together form an axial channel. The end edge of inner tube 5, or inner tube bottom 13, is spaced apart from closure element 1a of rotor shaft 1.

[0025] The hollow journal 6 has a first journal portion 14 and a second journal portion 15, which are integrally formed. In this embodiment, the first journal portion 14 carries a rotationally fixed spur gear ring 16, which meshes with a machine-external drive spur gear 17 in a transmission chamber 19 of a transmission 18 flanged to the machine 2. The first journal portion 14 extends from an output-side port 20 of the outer tube 4 and, from there, into the transmission chamber 19. The journal portions 14 and 15 merge into one another at a press-fit element 21 of the journal 6, where the journal 6 is pressed into the outer tube 4. To prevent relative rotation between the journal 6 and the outer tube 4, a wedge tooth 22 is provided between them. The wedge tooth 22 is particularly provided on the second journal portion 15, which is coaxially arranged in the outer tube 4. This ensures a sealed and rotationally fixed connection between the second journal portion 15 and the inner wall 8 of the outer tube. Along the longitudinal center axis 7 of the rotor shaft 1 , the annular end surface 23 of the second journal portion 15 and the inner tube 5 are spaced apart from each other at a linear distance.

[0026] Connecting pipe 3—— Figure 2 and Figure 3 , shown in the respective views, have a first connecting tube end 24 and a second connecting tube end 25. A first sealing ring seat 26 is provided at the first connecting tube end 24, into which a first sealing ring 27 engages in the rotor shaft 1. A second sealing ring seat 28 is provided at the second connecting tube end 25, into which a second sealing ring 29 engages in the rotor shaft 1. In this embodiment, the connecting tube 3 has a centering rib arrangement 30 and a docking flange 31 between the ends 24, 25, each of which is designed to allow a fluid to flow through. The centering rib arrangement 30 has three or more centering ribs 32, in this embodiment four, wherein the docking flange has at least one docking element 33, in this example four docking elements 33.

[0027] exist Figure 1As can be seen in the figure, the connecting tube 3 is arranged between the journal 6 and the inner tube 5. Its first connecting tube end 24 rests sealingly on the journal inner wall 34 of the journal 6 in the first journal part 14 on the outer circumference. A first sealing ring 27, seated in a first sealing ring seat 26, is clamped between the journal inner wall 34 and the connecting tube outer wall 35. In other words, the first sealing ring 27 is secured between the journal inner wall 34 and the connecting tube outer wall 35 in the first journal part 14 via the first sealing ring seat 26. The connecting tube 3 extends through the second journal part 15 and is coaxially supported therein by a centering rib arrangement 30, namely, a centering rib 32. The connecting tube 3 rests with its abutment flange 31 or abutment element 33 against the annular end face 23 of the second journal part 15. Furthermore, the connecting tube 3 projects from the second journal part 15 and thereby bridges the distance between the second journal part 15 and the inner tube 5. The connecting pipe 3, at its second connecting pipe end 25, seals into the inner pipe 5 or into the hollow interior 11 thereof. In this embodiment, the connecting pipe 3 and the inner pipe are sealed to one another via a connecting sleeve 36, which circumferentially surrounds the second connecting pipe end 25 and the inner pipe end 37 facing the connecting pipe 3. A second sealing ring 29 is secured via a second sealing ring seat 28 between the connecting pipe outer wall 35 and the connecting sleeve inner wall 38 of the connecting sleeve 36. In the second journal section 15, a journal annular space 39 is formed between the connecting pipe outer wall 35 and the journal inner wall 34, which communicates with the outer pipe annular space 10. In the first journal section 14, the journal 6 has a journal wall opening 40, here two or more journal wall openings 40, through which the journal annular space 39 communicates with the outlet port 20 of the outer pipe 4. In this embodiment, the output-side port 20 opening into the transmission chamber 19 and the journal annular space 39 are fluid-tightly sealed from one another on the outer circumference of the journal 6 , here by means of press-fit elements 21 .

[0028] from Figure 1 As can also be seen, according to this embodiment, outer tube inner wall 8 has a surface enlargement 41 in outer tube annular space 10, which has a plurality of annular grooves 42. Each of the annular grooves 42 forms a recess that extends radially from outer tube inner wall 8 toward outer tube outer wall 43. Since machine 2 is an electric motor, a rotor assembly 44 is fixed to outer tube outer wall 43 in a rotationally fixed manner.

[0029] During operation of the machine 2, a coolant, particularly in the form of oil, is supplied to the journal 6. For this purpose, the inlet line 45 of the coolant or oil module 46 is fluidically coupled to the journal port 47 of the journal 6. In this embodiment, a hollow connecting piece 48 is pressed into the journal port 47, with a radial shaft seal 49 disposed between the inlet line 47 and the journal port 47. The pump of the coolant or oil module 46 drives oil through the inlet line 45 and into the journal 6. The oil then flows through the journal 6 and into the connecting pipe 3. The oil continues to flow through the connecting pipe 3 and then out of the connecting pipe, into the inner pipe 5. The oil then flows out of the inner pipe 5 through the inner pipe wall opening 12 and the channel 13a and into the outer pipe annular space 10. There, the oil flows along the outer pipe inner wall 8, particularly along the surface enlargement 41, absorbing and dissipating the heat generated during the operation of the machine 2. The heated oil flows from the outer tube annular space 10 into the journal annular space 39, from there through the journal wall opening 40 and ultimately out of the rotor shaft 1 through the output-side port 20 of the outer tube 4. Since, in this embodiment, the rotor shaft 1 leads via the output-side port 20 into the transmission chamber 19 of the transmission 18, the oil flowing out of the rotor shaft 1 enters the transmission chamber 19.

[0030] The machine 2 and the motor vehicle each demonstrate how to more efficiently cool the rotor shaft of a machine, particularly an electric machine, through the rotor shaft 1, and in particular its connecting pipe 3. The core concept of the present invention is to ensure targeted flow guidance of the coolant oil in the thermally highly loaded areas of the rotor shaft 1, using the component topology described herein. This allows for targeted and optimized heat removal from the system, thereby preventing rotor overheating and, consequently, reduced performance of the machine 2.

[0031] Reference Signs List

[0032] 1 rotor shaft

[0033] 1a Closing element

[0034] 2 machines

[0035] 3 Connecting pipe

[0036] 4 outer tube

[0037] 5 Inner tube

[0038] 6 Journal

[0039] 7 Longitudinal center axis

[0040] 8 Inner wall of outer tube

[0041] 9 outer wall of inner tube

[0042] 10 Outer tube annular space

[0043] 11Inner space of inner tube

[0044] 12 Inner tube wall opening

[0045] 13 inner tube bottom

[0046] 13a groove

[0047] 14 First journal part

[0048] 15 Second journal part

[0049] 16 spur gear ring gear

[0050] 17 driving spur gear

[0051] 18 transmission

[0052] 19 Transmission cavity

[0053] 20 Output side port

[0054] 21 Press-fit components

[0055] 22 wedge teeth

[0056] 23 Annular end face

[0057] 24 First connecting pipe end

[0058] 25 Second connecting pipe end

[0059] 26 First sealing ring seat

[0060] 27 First sealing ring

[0061] 28 Second sealing ring seat

[0062] 29 Second sealing ring

[0063] 30 Centering rib arrangement structure

[0064] 31 Docking flange

[0065] 32 Centering rib

[0066] 33 Docking components

[0067] 34 Shaft neck inner wall

[0068] 35 outer wall of connecting pipe

[0069] 36 Connecting sleeve

[0070] 37 Inner tube end

[0071] 38 Connecting sleeve inner wall

[0072] 39 Journal annular space

[0073] 40 Journal wall opening

[0074] 41 Surface enlargement structure

[0075] 42 ring groove

[0076] 43 outer wall of outer tube

[0077] 44 rotor assembly

[0078] 45 Inflow pipe

[0079] 46 Coolant module or oil module

[0080] 47 Journal port

[0081] 48 Takeover

[0082] 49 radial shaft seals

Claims

1. A rotor shaft (1) for a machine (2), the rotor shaft comprising: - an outer tube (4), - an inner tube (5) which is coaxially arranged in the outer tube (4), wherein An outer tube annular space (14) is formed between the inner wall (8) of the outer tube and the outer wall (9) of the inner tube, and the inner tube (5) has an inner tube wall opening (12). a hollow journal (6), a first journal portion (14) of which projects from the outer tube (4), wherein a second journal portion (15) of the journal (6) is coaxially arranged in the outer tube (4), spaced apart from the inner tube (5) along the longitudinal center axis (7) of the rotor shaft (1), and connected to the inner wall (8) of the outer tube in a sealed and rotationally fixed manner, and having a journal wall opening (40), - a connecting pipe (3), the first connecting pipe end (24) of which rests sealingly on the inner wall (34) of the journal in the first journal part (14) on the outer circumference, wherein the connecting pipe (3) extends through the second journal part (14), protrudes from the second journal part (15) and thereby opens in a sealed manner into the inner pipe (5), wherein a journal annular space (39) communicating with the outer pipe annular space (10) is formed between the connecting pipe outer wall (35) and the inner wall (34) of the journal in the second journal part (15).

2. The rotor shaft (1) according to claim 1, characterized in that The connecting pipe (3) has a centering rib arrangement structure (30) on its connecting pipe outer wall (35), through which fluid can flow along the longitudinal center axis (7). By means of the centering rib arrangement structure, the connecting pipe (3) is coaxially supported in the second journal part (15).

3. The rotor shaft (1) according to claim 1 or 2, characterized in that The connecting pipe (3) has a butt joint flange (31) on its outer wall (35), through which fluid can flow along the longitudinal center axis (7). With the help of the butt joint flange, the connecting pipe (3) rests on the annular end face (23) of the second journal part (15).

4. The rotor shaft (1) according to any one of the preceding claims, characterized in that The connecting pipe (3) has a first sealing ring seat (26) at a first connecting pipe end (24), a first sealing ring (27) being fixed in the first sealing ring seat (26) and thereby fixed between an inner wall (34) of the journal in the first journal part (14) and an outer wall (35) of the connecting pipe.

5. The rotor shaft (1) according to any one of the preceding claims, characterized in that The connecting pipe (3) and the inner pipe (5) are connected to each other in a sealing manner by means of a connecting sleeve (36), which surrounds the second connecting pipe end (25) facing the inner pipe (5) and the inner pipe end (37) facing the connecting pipe (3) on the outer circumference.

6. The rotor shaft (1) according to any one of the preceding claims, characterized in that The connecting pipe (3) has a second sealing ring seat (28) at the second connecting pipe end (25), in which a second sealing ring (29) is fixed, in particular between the connecting pipe outer wall (35) and the connecting sleeve inner wall (38) of the connecting sleeve (36) according to claim 5.

7. The rotor shaft (1) according to any one of the preceding claims, characterized in that The inner wall (8) of the outer tube has a surface enlargement structure (41) in the outer tube annular space (10).

8. A machine (2), in particular an electric traction machine (2) for a motor vehicle, comprising a rotor shaft (1) according to any one of claims 1 to 7.

9. A motor vehicle comprising a machine (2) according to claim 8.

10. A connecting pipe (3) for a rotor shaft (1) according to any one of claims 1 to 7.

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