Rotor shaft for driving an electric machine, driving electric machine and motor vehicle

Abstract

The present invention relates to a rotor shaft (14) for driving a motor, the rotor shaft comprising a hollow shaft (22) radially surrounding a cavity (24) and a hollow spray bar (26) disposed in the cavity (24) and fixed at both ends to the inner side of the hollow shaft (22), the spray bar (26) having at least one opening (40) in its circumferential wall (38) through which coolant (32) can flow from the spray bar (26) into a region (42) of the cavity (24), the region being radially outwardly defined by the hollow shaft (22) and radially inwardly defined by the spray bar (26).

Description

Technical Field

[0001] The present invention relates to a rotor shaft for a drive motor, a drive motor for a motor vehicle, and a motor vehicle. Background Technology

[0002] A coolant supply system for a drive unit of an electrically operated motor vehicle is known from WO 2023 / 280555 A1. This coolant supply system includes an electric motor, in which a hollow rotor shaft is rotatably supported in bearing openings in an axially opposed housing wall, with a plurality of rotating bearings connected centrally. The coolant supply system has an electric motor hydraulic circuit with a coolant supply line for internal rotor cooling, which, particularly axially, supplies coolant by volumetric flow rate to the internal contour of the hollow rotor shaft on the oil supply side, such that the rotating bearing portion located on the coolant supply side can be cooled radially inward. A cooling medium path is provided in the hollow rotor shaft, extending to the rotating bearing portion axially opposed to the coolant supply side, thereby additionally allowing the rotating bearing portion axially opposed to the coolant supply side to also be cooled radially inward. A tubular coolant spray bar is connected to the coolant supply line, extending axially from the coolant supply side into the internal contour of the hollow rotor shaft. The coolant spray bar and the inner wall of the rotor hollow shaft together define an annular gap through which the coolant flows.

[0003] Furthermore, an electric traction machine for a motor vehicle is known from WO 2025 / 026637 A1. This traction machine includes a stator, a rotor rotatable relative to the stator about a rotation axis, a hollow rotor shaft (on which the rotor is torsionally fitted and within which oil can be guided), and a housing surrounding the stator and rotor. A spray bar, torsionally connected to the rotor shaft, is disposed within the cavity of the rotor shaft. This spray bar is configured to reciprocate oil within the rotor shaft along the inner wall of the defining cavity of the rotor shaft near the rotation axis. Summary of the Invention

[0004] The objective of this invention is to provide a solution that enables a particularly precise arrangement of the spray bar inside the rotor shaft.

[0005] According to the present invention, this task is solved by the technical solution of the independent claim. Other possible embodiments of the invention are disclosed in the dependent claims, the specification, and the drawings. Features, advantages, and possible designs set forth within the scope of the specification for one of the technical solutions of the independent claim can be at least similarly regarded as features, advantages, and possible designs of corresponding technical solutions of other independent claims and any possible combinations of technical solutions of the independent claims, and, if necessary, combined with one or more dependent claims.

[0006] This invention relates to a rotor shaft for a drive motor. The drive motor is particularly configured for use as a traction machine in motor vehicles. The auxiliary system means that the motor vehicle can be electrically driven by means of the drive motor. In addition to the rotor shaft, the drive motor may include a rotor and a stator torsionally fitted onto the rotor shaft, the rotor shaft and rotor being rotatable relative to the stator about an axis of rotation during operation. The rotor shaft currently comprises a hollow shaft radially surrounding a cavity. Furthermore, the rotor shaft includes a hollow spray bar disposed within the cavity and fixed at both ends to the inner sides of the hollow shaft. The spray bar has at least one opening in its circumferential wall through which coolant can flow from the spray bar into a region of the cavity, radially outwardly defined by the hollow shaft and radially inwardly defined by the spray bar. The rotor shaft is particularly rotationally symmetrical about an axis of rotation, about which it can rotate relative to the stator during operation. It is specified that coolant flows into the rotor shaft or into the cavity surrounded by the hollow shaft by means of the spray bar. The coolant can be guided or distributed particularly precisely within the cavity by means of the spray bar. By selecting the arrangement of the at least one opening of the spray bar, precise control can be achieved over how coolant flows into the region between the spray bar and the inner wall of the defining cavity of the hollow shaft, and / or how coolant flows between the outer side of the spray bar and the inner wall of the defining cavity of the hollow shaft. By correspondingly selecting the position of the at least one opening of the spray bar, the rotor shaft can be cooled particularly uniformly by the coolant during operation. This effectively avoids the risk of localized overheating of the rotor shaft, as well as the risk of localized overheating of the rotor when torsionally fitted to the rotor shaft during intended use. Since the spray bar is fixed at both ends to the inner side of the hollow shaft, torsional retention on the hollow shaft is achieved (and thus rotation with the hollow shaft about the axis of rotation during operation), and the spray bar is reliably fixed in its position within the cavity. Therefore, vibration of the spray bar, such as that that might occur when the spray bar is fixed at only one end, can be particularly well avoided. By fixing the spray bar at both ends to the inner side of the hollow shaft, the spray bar is reliably retained on the hollow shaft and reliably fixed in its position within the cavity. Therefore, the coolant can be guided with exceptional precision within the cavity using the spray bar.

[0007] In one possible extension of the invention, the spray bar is configured to be open at its first end, allowing coolant to flow through this first end into the spray bar volume surrounded by the spray bar. Alternatively, the spray bar may be closed at its second end, opposite the first end. For example, the spray bar may be covered and thus closed at its second end by the inner wall of a hollow shaft defining a cavity. This prevents coolant from flowing out at the second end of the spray bar. This ensures that coolant flows out of the spray bar volume only through the at least one opening in the circumferential wall of the spray bar. Therefore, coolant flow out of the spray bar volume by bypassing the at least one opening in the circumferential wall of the spray bar can be particularly well prevented. This allows the coolant to be guided particularly precisely within the cavity by means of the spray bar.

[0008] In another possible design of the invention, the spray bar is held at both ends by press-fitting onto the inside of the hollow shaft. A press-fit is a joining technique in which two components are connected to each other by compression, such that the two components (in this case, the spray bar and the hollow shaft) are joined together with an interference fit. Here, the spray bar is pressed into the hollow shaft. Each end of the spray bar forms a press-fit with the hollow shaft. This ensures that each end of the spray bar is reliably held on the hollow shaft and thus fixed in position relative to the hollow shaft. The corresponding press-fit allows the spray bar to be held particularly reliably on the hollow shaft without the need for additional auxiliary materials, such as adhesives.

[0009] In another possible design of the invention, the hollow shaft is provided with external teeth on one of its ends, through which the hollow shaft can engage with the transmission input shaft. It is also provided that the spray bar radially inwardly covers the external teeth within a length section. Specifically, the spray bar and the hollow shaft form a press fit in the region where the spray bar radially inwardly covers the external teeth of the hollow shaft. Therefore, within a length section of the hollow shaft, the hollow shaft can engage with the transmission input shaft via the external teeth and simultaneously be connected to the spray bar via a press fit. Thus, a length section of the hollow shaft can simultaneously fulfill a particularly large number of different functions. Because the hollow shaft has external teeth, through which it can engage with the transmission input shaft, the spray bar can form a press fit with the particularly smoothly constructed surface of the hollow shaft. This allows for a particularly simple and reliable press fit formation.

[0010] In another possible design of the invention, the hollow shaft is provided with internal teeth on one of its ends, through which the hollow shaft can engage with the transmission input shaft. It is also specified that the spray bar rests against the internal teeth for a length section, thereby holding one end of the spray bar on the hollow shaft via the internal teeth. In other words, the spray bar radially inwards covers the internal teeth. The spray bar thus forms a press fit with the corresponding teeth of the internal teeth of the hollow shaft. Because the rotor shaft has internal teeth, through which it can engage with the transmission input shaft, a transmission input shaft with a particularly small outer diameter can be provided, since the transmission input shaft needs to be inserted into the opening of the hollow shaft to engage with the internal teeth of the hollow shaft in order to engage with it. Therefore, the transmission input shaft can be constructed to be particularly lightweight.

[0011] In another possible embodiment of the invention, the spray bar is held on a hollow shaft at its first end by internal teeth and is provided with a sealing ring. This sealing ring completely covers all the gaps between the teeth of the internal teeth in the axial direction toward the second end of the spray bar and abuts against the radially outer side of the spray bar with its radially inner side. This prevents coolant from flowing into the region of the cavity on the outer side of the spray bar through the gaps between the teeth of the internal teeth, the region being radially outwardly defined by the hollow shaft and radially inwardly defined by the spray bar. Therefore, coolant is prevented from flowing into the region of the cavity, radially outwardly defined by the hollow shaft and radially inwardly defined by the spray bar, by bypassing the volume of the spray bar. Thus, the gaps between the teeth of the internal teeth are sealed in the region of the cavity radially outwardly defined by the hollow shaft and radially inwardly defined by the spray bar, with the sealing ring. Therefore, targeted and precise guidance of coolant by means of the spray bar can be achieved.

[0012] In another possible design of the invention, the at least one opening of the spray bar is provided to radially overlap with a region of the hollow shaft that is radially covered outward by the axial center of the rotor when the rotor shaft is used in a drive motor as specified. In other words, when the rotor shaft is used in a drive motor as specified, the at least one opening of the spray bar covers the axial center of the rotor in a radial direction toward the axis of rotation. Therefore, when coolant flows radially from the opening of the spray bar, the coolant flows directly to the region of the hollow shaft where the axial center of the rotor is located. Thus, when the rotor is torsionally fitted onto the hollow shaft, particularly efficient cooling of the central region of the rotor can be achieved.

[0013] In another possible design of the invention, the spray bar has a cross-sectional contraction downstream of the at least one opening in the direction of coolant flow through the spray bar. This cross-sectional contraction allows coolant to flow primarily out of the at least one opening of the spray bar, and the risk of coolant flowing past the opening without flowing out is kept particularly low. Therefore, it is possible for coolant flowing within the spray bar volume to reliably pass through the at least one opening of the spray bar and flow from the spray bar volume into the region of the cavity radially outward by the hollow shaft and radially toward the axis of rotation defined by the spray bar.

[0014] Furthermore, the present invention relates to a drive motor, particularly for motor vehicles, having a stator, a rotor rotatable relative to the stator about a rotational axis, and a rotor shaft (as already described in conjunction with the rotor shaft according to the invention), the rotor being torsionally fitted onto the rotor shaft. The drive motor is particularly a radial flux motor. Designing the drive motor using the aforementioned rotor shaft according to the invention enables particularly efficient cooling of the rotor shaft and the rotor, thereby allowing the drive motor to operate with exceptionally high efficiency.

[0015] Furthermore, the present invention relates to a motor vehicle, particularly an automobile, especially a passenger car, which has a drive motor (as already described in conjunction with the drive motor according to the invention). The drive motor is particularly a traction machine for a motor vehicle, configured to drive the motor vehicle by means of electrical energy.

[0016] Other features of the invention can be derived from the claims, drawings, and description of the drawings. The features and combinations thereof mentioned above in the specification, as well as the features and combinations thereof shown separately in the description and / or drawings below, may be used not only in the given combinations, but also in other combinations or individually without departing from the scope of the invention. Attached Figure Description

[0017] The attached image is as follows:

[0018] Figure 1 A schematic cross-sectional view of the rotor and rotor shaft for a motor vehicle drive motor is shown in a first embodiment; and

[0019] Figure 2 A schematic cross-sectional view of the rotor and rotor shaft used to drive the motor is shown in a second alternative embodiment. Detailed Implementation

[0020] In the accompanying drawings, identical and functionally identical elements are given the same reference numerals.

[0021] exist Figure 1 and 2The diagram shows a schematic cross-sectional view of an arrangement 10, which includes a rotor 12, a rotor shaft 14, and a transmission input shaft 16. The arrangement 10 is specifically configured as part of a motor vehicle drive motor, particularly a radial flux motor. The rotor 12 is torsionally mounted on the rotor shaft 14. The rotor 12 and rotor shaft 14 are configured to rotate about a rotational axis relative to the stator of the drive motor during operation. The rotor 12 currently includes a rotor base 18, on which balance discs 20 are respectively provided on each end face.

[0022] exist Figure 1 and 2 The rotor shaft 14 is shown in two different embodiments. What these two embodiments have in common is that the rotor shaft 14 includes a hollow shaft 22 that radially surrounds the cavity 24. Furthermore, the rotor shaft 14 includes a hollow spray bar 26 disposed within the cavity 24 and fixed at both ends to the inner side of the hollow shaft 22. It is specified that the spray bar 26 is held at both ends on the inner side of the hollow shaft 22 by press-fit 28. Figure 1 and 2 As can be seen particularly clearly in both embodiments, the spray bar 26 is configured to be open at its first end 30, thereby allowing coolant 32 to flow through this first end 30 into the spray bar volume 34 surrounded by the spray bar 26. It is also specified that the spray bar 26 is closed at its second end 36, opposite the first end 30. This prevents coolant 32 from flowing into or out of the spray bar volume 34 via the second end 36. Instead, the spray bar 26 has at least one opening 40 in its circumferential wall 38 through which coolant 32 can flow from the spray bar volume 34 into a region 42 of the cavity 24, which is radially outwardly defined by the hollow shaft 22 and radially inwardly, or radially toward the axis of rotation of the rotor shaft 14, defined by the spray bar 26, and particularly by its circumferential wall 38. In the present embodiment, the spray bar 26 has at least two openings 40 in its circumferential wall 38 through which coolant 32 can flow into the region 42 of the cavity 24. In two embodiments of the rotor shaft 14, the spray bar 26 is provided to have a cross-sectional contraction 44 downstream of the at least one opening 40 in the flow direction of the coolant 32 through the spray bar volume 34.

[0023] As in Figure 1 and 2It can also be seen particularly clearly that the opening 40 of the spray bar 26 is arranged radially overlapping the area below the hollow shaft 22, which is radially outwardly covered by the axial center of the rotor 18. In other words, the rotor 12 can be particularly well cooled in its axial center by allowing the coolant 32 flowing out of the opening 40 to flow directly into the area of ​​the hollow shaft 22 that radially inwardly covers the region of the rotor 12. The coolant 32 flowing in region 42 can flow radially outward along the wall of the cavity 24 of the hollow shaft 22 to the corresponding outflow opening 46, through which the coolant 32 can flow out of the cavity 24. After the coolant 32 flows out of the cavity 24 through the outflow opening 46, the coolant 32 can flow through at least one of the balance discs 20 to cool the balance discs 20.

[0024] exist Figure 1 In the embodiment of the rotor shaft 14 shown, the hollow shaft 22 has internal teeth 48, through which the hollow shaft 22 can mesh with the transmission input shaft 16. (As in...) Figure 1 As can also be seen, the spray bar 26 is specified to rest against the internal toothed portion 48, particularly forming a press fit 28 with the internal toothed portion 48. Thus, the spray bar 26 is held at one end, with its first end 30, via the internal toothed portion 48 on the hollow shaft 22. Furthermore, in Figure 1 In the illustrated embodiment, the rotor shaft 14 includes a sealing ring 50, which is currently configured as an O-ring. The sealing ring 50 completely covers all the gaps between the teeth of the internal teeth 48 in the axial direction A toward the second end 36 of the spray bar 26. Furthermore, the sealing ring 50 rests radially inward against the radially outward side of the spray bar 26. This prevents coolant 32 from flowing into the region 42 of the cavity 24 along the outer side of the spray bar 26 through the gaps between the teeth of the internal teeth 48.

[0025] exist Figure 2 In the illustrated embodiment, the hollow shaft 22 has an external tooth 52 on one of its ends, through which the hollow shaft 22 meshes with the transmission input shaft 16. Here, the spray bar 26 radially covers the external tooth 52 in a length section extending along the axial direction A. The radial direction R is perpendicular to the axial direction A. The axial direction A extends parallel to the longitudinal extension direction of the rotation axis of the rotor shaft 14.

[0026] This invention is based on the understanding that cooling of the stator lamination assembly and rotor lamination assembly is becoming increasingly important in the development of drive motors. Efficient cooling can optimize drive motors in terms of continuous power, weight, and efficiency.

[0027] To ensure uniform cooling of sides A and B of rotor 12, the coolant 32 should be distributed as symmetrically as possible within rotor shaft 14. For this purpose, a spray bar 26 is currently used in rotor shaft 14. This spray bar is currently constructed as a thin-walled sleeve pressed into hollow shaft 22. The spray bar 26 is currently a centrally perforated metal sleeve, which is fixed in hollow shaft 22 by press fit. The spray bar 26 has multiple openings 40 at the height of the middle of rotor 12, particularly at the middle of the rotor lamination assembly. These openings are currently constructed as discharge holes and enable symmetrical distribution of coolant 32. Currently, oil is used as the coolant 32. The coolant 32 flowing from rotor shaft 14 can be guided through an abutting balance disc 20, through which it can be used directly to cool the stator winding heads, or guided through special channels in the rotor lamination assembly to cool the magnets of rotor 12.

[0028] If the hollow shaft 22 has internal teeth 48 for transmitting torque to the transmission input shaft 16, the spray bar 26 is pressed into the tip circle diameter of the internal teeth 48 at its first end 30. The spray bar 26 can be pressed into a defined hole in the hollow shaft 22 at its second end 36. Alternatively, the spray bar 26 can be supported in the hollow shaft 22 by means of an O-ring at its second end 36. The spray bar 26 can be made of plastic. To seal oil in the area of ​​the internal teeth 48, a groove in which a sealing ring 50 is provided can be used.

[0029] If the hollow shaft 22 is as follows Figure 2 As shown, the nozzle 26, which has an external toothed portion 52 for transmitting torque to the transmission input shaft 16, is pressed into the defining hole of the hollow shaft 22 with its second end 36 and into the inlet of the hollow shaft 22 with its first end 30.

[0030] In summary, the present invention demonstrates how to realize a rotor shaft 14 having an integrated spray bar sleeve and thus a spray bar 26.

[0031] List of reference numerals

[0032] 10 Arrangement Device

[0033] 12 rotors

[0034] 14 rotor shafts

[0035] 16-speed transmission input shaft

[0036] 18 rotor base

[0037] 20 balance discs

[0038] 22 Hollow Shaft

[0039] 24 cavity

[0040] 26 spray boom

[0041] 28 pressure fit

[0042] 30 First end

[0043] 32 coolant

[0044] 34 spray bar volume

[0045] 36 Second end

[0046] 38 Zhou Xiangbi

[0047] 40 opening

[0048] Area 42

[0049] 44 contraction section

[0050] 46 outflow opening

[0051] 48 Internal teeth

[0052] 50 sealing ring

[0053] 52 External teeth

[0054] Axial direction

[0055] R radial direction

Claims

1. A rotor shaft (14) for driving a motor, the rotor shaft comprising: A hollow shaft (22) radially surrounds the cavity (24). A hollow spray bar (26) is disposed in the cavity (24) and fixed at both ends to the inside of a hollow shaft (22). The spray bar (26) has at least one opening (40) in its circumferential wall (38) through which coolant (32) can flow from the spray bar (26) into the following region (42) of the cavity (24), which is radially outwardly defined by the hollow shaft (22) and radially inwardly defined by the spray bar (26).

2. The rotor shaft (14) according to claim 1, characterized in that, The spray bar (26) is configured to be open at its first end (30), through which coolant (32) can flow into the spray bar volume (34) surrounded by the spray bar (26), and the spray bar (26) is closed at its second end (36) opposite to the first end (30).

3. The rotor shaft (14) according to claim 1 or 2, characterized in that, The spray bar (26) is held on the inside of the hollow shaft (22) at both ends by press fit (28).

4. The rotor shaft (14) according to any one of the preceding claims, characterized in that, The hollow shaft (22) has an external tooth (52) on one of its ends, through which the hollow shaft (22) can engage with the transmission input shaft (16), and the spray bar (26) covers the external tooth (52) radially inward in the length section.

5. The rotor shaft (14) according to any one of claims 1 to 3, characterized in that, The hollow shaft (22) has an internal tooth (48) on one of its ends, through which the hollow shaft (22) can engage with the transmission input shaft (16), and the spray bar (26) rests against the internal tooth (48) in the length section, thereby holding one end of the spray bar (26) on the hollow shaft (22) through the internal tooth (48).

6. The rotor shaft (14) according to claim 5, characterized in that, The spray bar (26) is held on the hollow shaft (22) by its first end (30) through the internal teeth (48) and is provided with a sealing ring (50) which completely covers all the gaps between the teeth of the internal teeth (48) in the axial direction toward the second end (36) of the spray bar (26) and abuts its radially inner side against the radially outer side of the spray bar (26), thereby preventing coolant (32) from flowing into the region (42) of the cavity (22) on the outer side of the spray bar (26) through the gaps between the teeth of the internal teeth (48), the region being radially outwardly defined by the hollow shaft (22) and radially inwardly defined by the spray bar (26).

7. The rotor shaft (14) according to any one of the preceding claims, characterized in that, The at least one opening (40) of the spray bar (26) is arranged to radially overlap with the following region of the hollow shaft (22), which is radially outwardly covered by the axial center of the rotor (12) when the rotor shaft (14) is used in the drive motor as specified.

8. The rotor shaft (14) according to any one of the preceding claims, characterized in that, The spray bar (26) has a cross-sectional contraction (44) downstream of the at least one opening (40) in the direction of coolant (32) flow through the spray bar (26).

9. A drive motor having a stator, a rotor (12) rotatable relative to the stator about a rotation axis, and a rotor shaft (14) according to any one of the preceding claims, the rotor being torsionally fitted on the rotor shaft.

10. A motor vehicle having a drive motor according to claim 9.

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