Rotor for a current-excited synchronous machine for a motor vehicle, and motor vehicle

Abstract

The invention relates to a rotor (10) for a current-excited synchronous machine for a motor vehicle, having a hollow rotor shaft (14) and a laminated core (16) that is seated for conjoint rotation on the rotor shaft (14) and has an annular yoke (42) and a plurality of pole shanks (44) protruding radially from the yoke (42), having at least one star disk (18) that is arranged on an end face of the laminated core (16) and around which a rotor winding (40) of the rotor (10) is placed, wherein the rotor winding (40) is wound around the pole shanks (44) of the laminated core (16), and comprising at least one cooling channel (24) configured to guide a cooling fluid (25) and the first region (26) of which extends through the hollow rotor shaft (14), the second region (28) of which extends radially outward from the rotor shaft (14), wherein the second region (28) is delimited at least by the star disk (1), and the third region (30) of which is delimited by the laminated core (16) and extends in an axial direction (RA) through the laminated core (16).

Description

[0001] Rotor for a current-excited synchronous machine for a motor vehicle as well as motor vehicle

[0002] The invention relates to a rotor for a current-excited synchronous machine for a motor vehicle and to a motor vehicle with a current-excited synchronous machine.

[0003] DE 102022 205 919 A1 discloses a rotor for an asynchronous machine, comprising a laminated core with axially extending short-circuit bars, a rotor shaft with a rotor shaft channel for transporting a coolant, comprising axially extending coolant channels which extend parallel to the short-circuit bars, and axially end-arranged balancing discs. The two axially end-arranged balancing discs are equipped with radial connecting channels which are configured to form a direct or indirect fluid-carrying connection between the rotor shaft channel and the axial coolant channels.

[0004] DE 10 2022 206 147 A1 further discloses an electric machine comprising a laminated core, a short-circuit ring, and a shaft, which in turn includes at least one cooling channel for guiding coolant. The electric machine includes at least one guide element for deflecting coolant exiting a shaft bore, wherein the guide element is formed as part of the short-circuit ring.

[0005] Furthermore, DE 10 2022 003 198 A1 discloses an electric machine with a stator having at least one winding with at least one winding head, and

[0006] 24-0188 ABZ EXA 18.10.2024 with a rotor which has a rotor shaft with at least one cooling channel through which a coolant can flow. The cooling channel has at least one outlet opening through which the coolant can be discharged from the cooling channel, which is overlapped outwards in the radial direction of the electric machine by the winding head.

[0007] The object of the present invention is to provide a solution by which a current-excited synchronous machine for a motor vehicle can be cooled particularly well.

[0008] This problem is solved according to the invention by the subject matter of the independent claims. Further possible embodiments of the invention are disclosed in the dependent claims, the description, and the figures. Features, advantages, and possible embodiments set forth in the description for one of the subject matter of the independent claims are to be regarded, at least analogously, as features, advantages, and possible embodiments of the respective subject matter of the other independent claims, as well as of any possible combination of the subject matter of the independent claims, optionally in conjunction with one or more of the dependent claims.

[0009] The invention relates to a rotor for an electrically excited synchronous machine for a motor vehicle, in particular a car, especially a passenger car. The electrically excited synchronous machine can also be referred to as a separately excited synchronous machine. In the electrically excited synchronous machine, a constantly magnetized rotor is driven synchronously by a rotating magnetic field in the stator of the electrically excited synchronous machine. A running synchronous machine has a motion synchronous with the applied alternating voltage. In the electrically excited synchronous machine, the field in the rotor is generated by electromagnetic external excitation with a field coil on the rotor and current supply via slip rings. The rotor for the electrically excited synchronous machine has a hollow rotor shaft and a laminated core mounted non-rotatably on the rotor shaft. The laminated core has an annular yoke and a plurality of pole pieces projecting from the radial yoke.In particular, the laminated core with a wall that radially limits the yoke inwards rests against an outer side of the rotor shaft.

[0010] 24-0188 ABZ EXA 18.10.2024 The rotor further comprises at least one star disk, which is arranged on an end face of the laminated core and around which a rotor winding of the rotor is wound. It is possible that the rotor has two star disks, a first star disk and a second star disk, which are located on opposite end faces of the laminated core and around which the rotor winding is wound. The rotor winding is wound around the pole legs of the laminated core. The first star disk rests against a first end face of the laminated core, and the second star disk rests against a second end face of the laminated core opposite the first in the axial direction of the rotor. The axial direction runs parallel to a longitudinal extension direction of the rotor's axis of rotation, about which the rotor is rotated relative to the stator during operation.The respective end faces of the lamination stack define the axial boundary of the lamination stack to the opposite sides.

[0011] Furthermore, the rotor is provided to include at least one cooling channel designed to carry a cooling fluid. The cooling fluid is, in particular, a coolant, especially oil. The cooling fluid is designed to absorb and dissipate heat from the rotor, thereby cooling the rotor. The cooling channel is provided to have a first section, a second section, and a third section. The cooling fluid flows through the cooling channel first through the first section, then through the second section, and subsequently through the third section. This means that the second section is located downstream of the first section in the direction of fluid flow through the cooling channel, and the third section is located downstream of the second section in the direction of fluid flow through the cooling channel.It is provided that the first section of the cooling channel extends through the hollow rotor shaft, the second section of the cooling channel extends radially outwards from the rotor shaft with its longitudinal direction and is bounded at least by the first star disk, and the third section of the cooling channel is bounded by the laminated core and extends axially through the laminated core. In particular, the longitudinal direction of the cooling channel in the first section is at least substantially parallel to the axial direction, in the second section at least substantially parallel to the radial direction – and thus perpendicular to the axial direction – and in the third section of the cooling channel at least substantially in the axial direction, although it is possible that the course of the cooling channel in the third section has a radial component. The guiding of the...

[0012] 24-0188 ABZ EXA 18.10.2024 The transfer of cooling fluids from the first to the third section of the cooling channel via the second section of the cooling channel thus occurs, with respect to the axial direction of the rotor, between the laminated core and a winding head resulting from the rotor winding being wrapped around the star disk. This winding head is located on the side of the star disk, particularly the first star disk, facing away from the laminated core in the axial direction. It is possible that the second section of the cooling channel is provided by the first star disk, and that the cooling channel is delimited by the second star disk in a fourth section. The cooling fluid carried in this fourth section can be directed into the rotor's surroundings. The cooling fluid flows through the fourth section after the third section.This means that the fourth section is located downstream of the third section of the cooling channel in the direction of coolant flow. In other words, the first star disk can direct the coolant to the section of the cooling channel that passes through the laminated core, and the second star disk can direct the coolant away from the third section of the cooling channel, which also passes through the laminated core, particularly towards the rotor. The described rotor allows the laminated core of a current-excited synchronous machine to be cooled by means of the cooling channel located within the core. Despite the winding heads being located at the rotor's end face, a reliable supply of coolant from the first section of the cooling channel, located inside the hollow rotor shaft, to the third section of the cooling channel, located within the laminated core, is ensured.This avoids the need to route the cooling fluid through the rotor winding head of the rotor to reach the laminated core.

[0013] It is possible that the rotor comprises several cooling channels, the first sections of which coincide. In other words, these multiple cooling channels share at least one longitudinal section of the hollow rotor shaft as their respective first section. These cooling channels then divide, each having a separate second section and a separate third section. Furthermore, it is possible that each of the cooling channels has a separate fourth section.

[0014] In a possible further development of the invention, it is provided that the second area extends over its entire radially extending length in the axial direction of the rotor between an end face of the laminated core and the area at this end face.

[0015] 24-0188 ABZ EXA 18.10.2024 is arranged adjacent to the star disk. The second section of the cooling channel is circumferentially bounded by both the lamination stack and the star disk. This second section extends radially from the rotor shaft between the lamination stack and the star disk to an inlet opening in the lamination stack, through which the cooling fluid can flow into the third section of the cooling channel. Because the second section of the cooling channel is arranged axially between the star disk and the lamination stack, the rotor can be manufactured particularly easily, especially compared to an arrangement in which the second section extends only within the star disk.

[0016] In this context, it is specifically intended that the second section of the cooling channel is bounded by a groove in the star disk and the end face of the laminated core that abuts this star disk. The end face of the laminated core is designed to be flat. To insert the second section of the cooling channel into the rotor, the groove is machined into the star disk. The groove's path defines the path of the second section of the cooling channel, and its cross-section defines the cross-section of the second section. By machining the groove into the star disk, the second section of the cooling channel can be inserted into the rotor particularly easily. The groove can, for example, be milled into the star disk.

[0017] In a further possible embodiment of the invention, the third section of the cooling channel is located within a pole leg of the laminated core. For example, the third section of the cooling channel can be formed by punching out sections in the pole legs of the laminated core stacks, which are stacked in a direction parallel to the axial direction. The arrangement of the third section of the cooling channel within a pole leg of the laminated core enables particularly efficient cooling of the pole leg by means of cooling fluid flowing in the cooling channel. In particular, the rotor can be provided with several cooling channels, with at least one cooling channel running through each pole leg of the rotor. This ensures that all pole legs of the laminated core can be reliably cooled during rotor operation.This allows the rotor to be operated particularly efficiently.

[0018] 24-0188 ABZ EXA 18.10.2024 In this context, it may be provided, in particular, that the third section of the cooling channel, in its cross-section extending perpendicular to the axial direction of the rotor, has a greater length in the radial direction of the rotor than its width in the circumferential direction of the rotor. In other words, the cross-section of the third section of the cooling channel is elongated and extends within a particularly long radial section of the pole leg. Furthermore, it is achieved that the third section of the cooling channel occupies a particularly small portion of the circumferential width of the pole leg, thereby minimizing disturbance to the magnetic field lines running radially through the pole leg by the cooling channel or the cooling fluid flowing in the cooling channel. As a result, the rotor can be operated with particularly high energy efficiency.

[0019] In a further possible embodiment of the invention, the third section of the cooling channel extends within the yoke of the laminated core. It is possible for the rotor to have at least one cooling channel whose third section extends within a pole leg of the laminated core, and at least one further cooling channel whose third section extends within the yoke of the laminated core. Because the third section of the cooling channel extends within the yoke of the laminated core, the yoke of the laminated core can be cooled particularly efficiently by means of the cooling fluid flowing through the cooling channel. In particular, the cooling channel with its third section can be arranged in an area of ​​high heat generation in the rotor, whereby the rotor, and especially the laminated core of the rotor, can be cooled particularly efficiently in this area of ​​high heat generation by means of the cooling fluid flowing through the third section of the cooling channel.

[0020] In this context, it is specifically designed that the third section of the cooling channel, in its cross-section perpendicular to the axial direction of the rotor, has a greater width in the circumferential direction of the rotor than its length in the radial direction. In other words, this third section of the cooling channel, which runs within the yoke of the laminated core, has an elongated cross-section, with the cross-section being wider in the circumferential direction than it is long in the radial direction. This allows for a particularly large contact area between the cooling fluid and the laminated core due to the exceptionally large outer surface area of ​​the cooling channel in this third section, thereby dissipating heat particularly efficiently via the cooling fluid.

[0021] 24-0188 ABZ EXA 18.10.2024 from the yoke of the laminated core. Furthermore, due to the elongated design of the cross-section of the cooling channel in the third area within the yoke of the laminated core, it can be achieved that magnetic field lines running within the cooling channel are disturbed very little by the cooling channel or by the cooling fluid flowing in the cooling channel, thus enabling particularly energy-efficient operation of the rotor.

[0022] In a further possible embodiment of the invention, the rotor is provided with a backwater edge which projects radially from the outside inwards into the cooling channel in the third region. In particular, the backwater edge is arranged in an end region of the third region of the cooling channel. For example, the backwater edge can define a rear end of the third region of the cooling channel with respect to the flow direction of the cooling fluid. In other words, the third region can thus be limited at its rear end with respect to the flow direction by means of the backwater channel. The backwater edge serves to cause a backwater effect of the cooling fluid in the third region of the cooling channel in order to prevent the cooling fluid from merely thinly wetting one wall of the cooling channel in the third region due to unimpeded outflow.The baffle edge is used to adjust the radial height of the cooling fluid level in the third section. This means that, depending on how far the baffle edge projects radially beyond the wall of the cooling channel that radially defines the third section, the desired level of the cooling fluid level in the third section during operation can be set. Without the baffle edge, the centrifugal forces acting on the cooling fluid during operation, when the rotor rotates around its axis, would cause it to flow freely and at high speed axially through the third section, resulting in the cooling fluid forming only a thin film on the wall radially defining the cooling channel.Furthermore, by accumulating the cooling fluid at the stagnation point, turbulent flow of the cooling fluid can be achieved in the third section of the cooling channel, resulting in particularly efficient heat transfer from the laminated core to the cooling fluid flowing in this third section. Consequently, the residence time of the cooling fluid in this third section can be extended, leading to a particularly high and efficient heat transfer from the laminated core to the cooling fluid.

[0023] 24-0188 ABZ EXA 18.10.2024 In a further possible embodiment of the invention, the rotor comprises at least one heat sink which axially covers the star disk on its outer surface facing away from the laminated core. It is possible for the rotor to comprise one heat sink for each star disk, with each heat sink axially covering one star disk on its outer surface facing away from the laminated core. In particular, the heat sink is made of aluminum, which allows heat to be dissipated particularly efficiently from the respective star disk and the rotor winding head associated with that star disk.Furthermore, the rotor is provided with at least one cooling channel, in particular at least one cooling channel for each cooling element, by means of which cooling fluid guided in the rotor shaft can be directed to an outer surface of the cooling element facing away from the star disk, thereby allowing this outer surface of the cooling element to be exposed to the cooling fluid. In other words, the cooling fluid is directed from the rotor shaft to the outer surface of the cooling element by means of the at least one cooling channel, thereby allowing this outer surface of the cooling element to be wetted with the cooling fluid and consequently cooled by the cooling fluid. The outer surface of the cooling element is arranged axially opposite an inner surface of the cooling element facing the star disk. The outer surface of the star disk is arranged axially opposite an inner surface of the star disk facing the laminated core.The rotor's at least one heat sink enables particularly efficient heat dissipation from the star disk, which is axially covered by the heat sink, and from the rotor winding head. The cooling fluid impacting the outer surface of the heat sink allows for highly efficient cooling of the heat sink itself. This highly efficient cooling of the heat sink, as well as the efficient cooling of the star disk and the rotor winding head by means of the heat sink, allows for highly efficient rotor operation and effectively prevents rotor overheating.

[0024] The invention further relates to a motor vehicle with an electrically excited synchronous machine, which comprises a stator and a rotor rotatable relative to the stator about an axis of rotation, as already described in connection with the rotor according to the invention. The particularly efficient cooling of the rotor described above allows the electrically excited synchronous machine to operate more efficiently.

[0025] 24-0188 ABZ EXA 18.10.2024 can be operated particularly efficiently, thereby powering the motor vehicle particularly efficiently using electrical energy. The motor vehicle in question is, in particular, a motor car, especially a passenger car.

[0026] Further features of the invention may become apparent from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features shown below in the description of the figures and / or in the figures themselves, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention.

[0027] The drawing shows in:

[0028] Fig. 1 shows a schematic sectional view of a rotor for a current-excited synchronous machine for a motor vehicle with a rotor shaft, a laminated core, a first star disk and a second star disk;

[0029] Fig. 2 shows a schematic cross-section of the rotor's laminated core along the section line A:A from Fig. 1;

[0030] Fig. 3 shows a schematic longitudinal section of the rotor;

[0031] Fig. 4 shows an enlarged view of the area of ​​the rotor marked “D” in Fig. 3;

[0032] Fig. 5 shows an enlarged view of the area of ​​the rotor marked “E” in Fig. 3;

[0033] Fig. 6 shows an enlarged view of the area of ​​the rotor marked “F” in Fig. 3;

[0034] Fig. 7 a schematic perspective view of the first star disk; and

[0035] Fig. 8 is a schematic perspective view of the second star disk.

[0036] 24-0188 ABZ EXA 18.10.2024 In the figures, identical and functionally equivalent elements are provided with the same reference symbols.

[0037] Figure 1 shows a schematic longitudinal section along an axial direction RA of a rotor 10 for an electrically excited synchronous machine for a motor vehicle. The electrically excited synchronous machine (SSM) is an electric traction machine that can electrically propel the motor vehicle. In addition to the rotor 10, the SSM comprises a stator, relative to which the rotor 10 can be rotated about an axis of rotation 12 during operation. The axis of rotation 12 extends along the axial direction RA. The rotor 10 is rotationally symmetrical with the axis of rotation 12 as its axis of symmetry. A radial direction RR of the rotor 10 is perpendicular to the axial direction RA. The rotor 10 comprises a hollow rotor shaft 14, a laminated core 16 fixed to the hollow rotor shaft 14, a first star disk 18, and a second star disk 20.The first star disk 18 and the second star disk 20 are located on axially opposite end faces of the laminated core 16. The respective star disks 18 and 20 serve as winding aids for winding a rotor winding 40 on the respective end faces of the laminated core 16. Each star disk 18 and 20 has rounded edges on its outer surface facing away from the laminated core 16 to guide the wire of the rotor winding 40.

[0038] In the present design, the rotor 10 further comprises two cooling elements 22 (not shown in Fig. 1), each of which axially covers one of the star disks 18, 20. The rotor 10 is further provided to have several cooling channels 24, which are designed to allow a cooling fluid, in particular a coolant, especially oil, to flow through, thereby cooling the rotor 10. Each of the cooling channels 24 has a first section 26, a second section 28, a third section 30, and a fourth section 32, with the first sections 26 of all cooling channels 24 coinciding. As can be seen particularly well in Fig. 1, the cooling fluid 25 flows through all cooling channels 24 first through the first section 26, then through the second section 28, then through the third section 30, and finally through the fourth section 32.The first section 26 of all cooling channels 24 extends through the hollow rotor shaft 14. The flow direction of the cooling fluid 25 within the first section 26 is at least substantially axial RA. ES.

[0039] 24-0188 ABZ EXA 18.10.2024 It can be provided that the cooling fluid 25 is injected into the cavity 36 enclosed by the rotor shaft 14 by means of a lance 34. The first section 26 of the cooling channels 24 extends over an axial length of the rotor 10 that is greater than the axial length of the laminated core 16. The respective second sections 28 of the respective cooling channels 24 extend with their longitudinal direction in the radial direction RR, whereby the cooling fluid 25 flowing through the second section 28 of the respective cooling channel 24 flows radially outwards from the rotor shaft 14. The third section 30 of the respective cooling channel 24 extends with its longitudinal direction at least substantially axially through the laminated core 16. In particular, the third area 30 extends over the entire axial length of the lamination stack 16 through the lamination stack 16.The cooling fluid 25 flowing into the third section 30 of the respective cooling channel 24 thus flows at least substantially in an axial direction through the laminated core 16. The cooling fluid 25 flowing out of the third section 30 can be guided radially outwards into the vicinity of the rotor 10 by means of the fourth section 32 of the respective cooling channel 24. The first section 26, which is the same for all cooling channels 24, is thus circumferentially bounded by the rotor shaft 14. Each of the cooling channels 24 is circumferentially bounded by the laminated core 16 in the respective third section 30. In the second section 28 of the respective cooling channel 24, the respective cooling channel 24 is circumferentially bounded by both the first star disk 18 and the laminated core 16. In the fourth section 32, the respective cooling channel 24 is circumferentially bounded at least by the second star disk 20 and, if applicable, additionally by the laminated core 16.In this context, "circumferential" refers to a circumferential boundary around the flow direction of the fluid in the respective area of ​​the respective cooling channel 24.

[0040] Figure 3 shows a more detailed schematic longitudinal section of the rotor 10. Figure 3 also shows the two cooling sinks 22 and the respective rotor winding heads 38 of the rotor 10.

[0041] In Fig. 2, the laminated core 16 with the rotor winding 40 of the rotor 10 is shown in a schematic sectional view along line A:A from Fig. 1. The laminated core 16 comprises a plurality of rotor laminations stacked on top of each other in the axial direction RA. As can be seen particularly well in Fig. 2, the laminated core 16 is designed to form an annular winding that rotates around the rotor shaft 14.

[0042] 24-0188 ABZ EXA 18.10.2024 yoke 42 and a plurality of pole legs 44 projecting radially from the yoke 42. At the respective radially outer ends of each pole leg 44, pole shoes 46 are arranged. This means that each pole leg 44 is bounded radially outwards by a pole shoe 46. The pole legs 44 thus extend in the radial direction RR from the yoke 42 to the respective pole shoe 46 assigned to that pole leg 44. The respective pole legs 44 are wound with the rotor winding 40. For clarity, only some of the pole legs 44 and some of the pole shoes 46 are provided with the corresponding reference numeral. In this case, it is provided that the third section 30 of the respective cooling channels 24 extends in the axial direction RA through each pole leg 44.In other words, the third section 30 of a cooling channel 24 associated with each pole leg 44 extends axially in the direction RA. For clarity, only some of the cooling channels 24 and some of the third sections 30 are provided with their corresponding reference numerals. In Fig. 2, the axial direction RA extends into the plane of the image, while the radial direction RR extends radially outwards from the axis of rotation 12 and perpendicular to the axial direction RA.

[0043] The present design provides that the respective cooling channels 24 in the third region 30 extending within the pole leg 44 have a cross-section perpendicular to the axial direction RA, which is elongated. As can be seen particularly well in Fig. 2, the cooling channels 24 in the respective third regions 30 are designed to have a greater length in the radial direction RR of the rotor 10 than their width in the circumferential direction of the rotor 10. This ensures that the magnetic field lines 48 running through the pole legs 44, which are indicated by dashed lines in Fig. 2, are minimally affected by the respective cooling channels 24 or the cooling fluid 25 flowing in the cooling channels 24. For the sake of clarity, only some of the magnetic field lines 48 are indicated in Fig. 2.It is possible that the respective third sections 30 of the respective cooling channels 24 alternatively extend within the yoke 42 of the laminated core 16 in the axial direction RA, or that the rotor 10 has additional cooling channels 24 not shown in Fig. 2, the respective third sections 30 of which extend through the yoke 42 of the laminated core 16 in the axial direction RA. It may be provided that these cooling channels 24 extending within the yoke 42 have a larger, circumferential cross-section in their respective third sections 30, perpendicular to the axial direction RA of the rotor 10.

[0044] 24-0188 ABZ EXA 18.10.2024 of the rotor 10 have a width extending in the radial direction RR of the rotor 10. This means that the magnetic field lines 48 are particularly little affected by the cooling channels 24 extending through the yoke 42 or by the cooling fluid 25 flowing in these cooling channels 24.

[0045] Figures 4, 5, and 6 show enlarged views of the respective areas of the rotor 10 labeled D, E, and F in Figure 3. Figure 4 shows an enlarged view of area D, Figure 5 shows an enlarged view of area E, and Figure 6 shows an enlarged view of area F. Figure 4 shows an enlarged view of the transition of one of the cooling channels 24 from its second section 28 to its third section 30. Figure 5 shows an enlarged view of the transition of one of the cooling channels 24 from its third section 30 to its fourth section 32.

[0046] As can be seen particularly well in Fig. 4, the second section 28 is arranged in the axial direction RA between the first star disk 18 and the lamination stack 16 along its entire radial length RR. As can also be seen particularly well in Fig. 4, the second section 28 of the cooling channel 24 is formed by a first groove 50 in the first star disk 18, the longitudinal extension of which runs in the radial direction RA. This first groove 50 on the side of the first star disk 18 facing the lamination stack 16 is at least partially covered in the axial direction by the end face of the lamination stack 16 facing the first star disk 18, whereby the end face of the lamination stack 16, together with the walls of the first star disk 18 that define the first groove 50, circumferentially delimits the cooling channel 24 in the second section 28.

[0047] In Fig. 5, the transition of the cooling channel 24 from the third region 30 to the fourth region 32 can be seen. In the fourth region 32, the cooling channel 24 is defined by a second groove 52 in the second star disk 20. Here, the fourth region 32 of the cooling channel 24 can be bounded circumferentially, at least partially, by the walls of the second star disk 20 that define the second groove 52, as well as by the cooling element 22 that axially covers the second star disk 20 outwards and / or the end face of the laminated core 16 that abuts the second star disk 20.

[0048] As can be seen particularly well in Figures 4 and 5, it is provided here that the rotor 10 has a first jamming edge 54 and a second jamming edge 56.

[0049] 24-0188 ABZ EXA 18.10.2024. The baffle edges 54, 56 each project radially from the outside inwards, and thus from the outside inwards in the direction of the axis of rotation 12, into the cooling channel 24 in the third section 28. By means of the respective baffle edges 54, 56, a radially oriented height of the cooling fluid level of the cooling fluid 25 can be set during operation of the rotor 10 in the third section 30 of the cooling channel 24. For this purpose, the first baffle edge 54 is located in an initial section of the third section 30 through which the cooling fluid 25 flows when entering the third section 30, and the second baffle edge 56 is located in an outlet section of the third section 30 through which the cooling fluid 25 flows when exiting the third section 30.By means of the damming edges 54, 56, the cooling fluid 25 is thus dammed up in the third area 30 of the cooling channel 24 during operation in order to achieve, firstly, a particularly long residence time of the cooling fluid 25 in the third area 30 of the cooling channel 24, secondly, a particularly large wetting of the walls of the sheet metal stack 16 bounding the third area 30 of the cooling channel 24 and, furthermore, to establish a turbulent flow of the cooling fluid 25 in the third area 30, thereby enabling a particularly high heat transfer.In this case, both the first stagnation edge 54 and the second stagnation edge 56 are each provided by the lamination stack 16, so that the force acting on the accumulated cooling fluid 25 due to centrifugal forces acts only on the wall of the lamination stack 16 that radially outwards delimits the cooling channel 24 in the third area 30, and as far as possible not in a contact area of ​​the respective star disks 18, 20 with the end faces of the lamination stack 16. A radial escape of cooling fluid 25 along a contact surface of the respective star disk 18, 20 and the respective associated end face of the lamination stack 16 in radial direction RR from the rotor 10 can thus be particularly well prevented.

[0050] Figure 6 shows a schematic sectional view of the rotor shaft 14 and the cooling element 22, which is radially attached to the outside of the rotor shaft 14 and which axially covers the first star disk 18. It can be seen that the rotor 10 includes a cooling element channel 58, which is partially bounded by the rotor shaft 14 and partially by the cooling element 22. This channel is designed to guide the cooling fluid 25 flowing in the cavity 36 of the rotor shaft 14 to an outer surface 60 of the cooling element 22 facing away from the first star disk 18. This allows the outer surface 60 of the cooling element 22 to be exposed to the cooling fluid 25, and in particular to be wetted by the cooling fluid 25, thus enabling particularly efficient cooling of the cooling element 22. The cooling element 22 covers the

[0051] 24-0188 ABZ EXA 18.10.2024 first star disk 18 axially outwards to its outer side facing away from the sheet metal package 16.

[0052] Fig. 7 shows a schematic perspective view of the first star disk 18, and Fig. 8 shows a schematic perspective view of the second star disk 20. In Fig. 7, the multiple first grooves 50 are particularly visible. These grooves extend radially RR VOH from the edge of the first star disk 18, which faces the axis of rotation 12 of the rotor 10 and forms its inner boundary, and radially RR outwards in their longitudinal direction. In this case, the first star disk 18 has a first groove 50 for each cooling channel 24, with one cooling channel 24 being provided for each pole leg 44 of the laminated core 16. As shown in Fig.As can be seen in Figure 8, the second star disk 20 has a second groove 52 for each cooling channel 24, which extends radially in its longitudinal direction towards the axis of rotation 12 of the rotor 10, starting from an edge of the second star disk 20 that defines its radial outer boundary. Both the first grooves 50 and the second grooves 52 each extend only over a portion of the shortest path from an inner edge of the respective star disk 18, 20 that defines its radial outer boundary to the axis of rotation 12, to an outer edge that defines the respective star disk 18, 20 radially outwards.

[0053] As can be seen particularly well in Figures 7 and 8, the respective star disks 18 and 20 are designed to be rotationally symmetrical. In the rotor 10 shown in the figures, cooling channels 24 are punched into the lamination stack 16 of the rotor 10. Such cooling channels 24 can be implemented by punching at least substantially no additional cost. In their third section 30, which extends through the lamination stack 16, the respective cooling channels 24 have a cross-section perpendicular to the axial direction RA, which is at least substantially elongated. The longitudinal direction of this shape runs at least substantially parallel to the electromagnetic flux in the respective section, thus ensuring that the respective cooling channel 24 presents only the smallest possible obstacle to the electromagnetic flux in the respective section.

[0054] 24-0188 ABZ EXA 18.10.2024 In the rotor 10 shown in the figure, the cooling fluid 25 is guided through the hollow rotor shaft 14, with a portion of the cooling fluid flow being used to cool the outer surface 60 of the cooling element 22, which axially covers the first star disk 18. The remainder of the cooling fluid flow is guided radially outwards between the first star disk 18 and the laminated core 16. The respective second sections 28 of the cooling channels 24 can be implemented in a forging process of the first star disk 18 at least substantially no additional cost. The cooling fluid 25 flows out of the rotor 10 in an axial direction behind the second star disk 20.

[0055] Overall, the invention demonstrates how rotor lamination slot cooling can be implemented in a current-excited synchronous machine of a motor vehicle.

[0056] 24-0188 ABZ EXA 18.10.2024 Reference List

[0057] 10 Rotor

[0058] 12 Rotation axis

[0059] 14 hollow rotor shaft

[0060] 16 sheet metal packages

[0061] 18 first star disc

[0062] 20 second star disc

[0063] 22 heat sinks

[0064] 24 Cooling channel

[0065] 25 Cooling fluid

[0066] 26 first section of the cooling channel

[0067] 28 second section of the cooling channel

[0068] 30 third section of the cooling channel

[0069] 32 fourth section of the cooling channel

[0070] 34 lance

[0071] 36 cavity

[0072] 38 Rotor winding head

[0073] 40 Rotor winding

[0074] 42 yoke

[0075] 44 Polish thigh

[0076] 46 Pole shoe

[0077] 48 Magnetic field line

[0078] 50 first groove

[0079] 52 second groove

[0080] 54 first jam edge

[0081] 56 second jam edge

[0082] 58 Heat sink cooling channel

[0083] 60 Outside of the heat sink 22

[0084] RA axial direction

[0085] RR radial direction

[0086] 24-0188 ABZ EXA 18.10.2024

Claims

Patent claims 1. Rotor (10) for a current-excited synchronous machine for a motor vehicle, comprising a hollow rotor shaft (14), a laminated core (16) fixed to the rotor shaft (14) and comprising an annular yoke (42) and a plurality of pole arms (44) projecting radially from the yoke (42), with at least one star disk (18) arranged on an end face of the laminated core (16) and around which a rotor winding (40) of the rotor (10) is wound, the rotor winding (40) being wound around the pole arms (44) of the laminated core (16), and with at least one cooling channel (24) designed for guiding a cooling fluid (25), the first region (26) of which extends through the hollow rotor shaft (14), the second region (28) of which extends radially outwards from the rotor shaft (14), the second region (28) being bounded at least by the star disk (18),and whose third region (30) is bounded by the laminated core (16) and extends in the axial direction (RA) through the laminated core (16).

2. Rotor (10) according to claim 1, characterized in that the second region (28) is arranged in the axial direction (RA) of the rotor (10) over its entire radially extending length (RR) between an end face of the laminated core (16) and the star disk (18) abutting this end face.

3. Rotor (10) according to claim 2, characterized in that the second area (28) of the cooling channel (24) is limited by a groove (50) in the star disk (18) and the end face of the laminated core (16) abutting this star disk (18).

4. Rotor (10) according to one of the preceding claims, characterized in that the third area (30) of the cooling channel (24) extends within a pole leg (44) of the laminated core (16). 24-0188 ABZ EXA 18.10.2024 5. Rotor (10) according to claim 4, characterized in that the third region (30) of the cooling channel (24) has a cross-section perpendicular to the axial direction (RA) of the rotor (10) that has a greater length extending in the radial direction (RR) of the rotor (10) than its width extending in the circumferential direction of the rotor (10).

6. Rotor (10) according to one of the preceding claims, characterized in that the third area (30) of the cooling channel (24) runs within the yoke (42) of the laminated core (16).

7. Rotor (10) according to claim 6, characterized in that the third region (30) of the cooling channel (24) has a cross-section perpendicular to the axial direction (RA) of the rotor (10) that has a greater width in the circumferential direction of the rotor (10) than a length in the radial direction (RR) of the rotor (10).

8. Rotor (10) according to one of the preceding claims, characterized in that the rotor (10) has a stagnation edge (56) which projects radially from the outside to the inside into the cooling channel (24) in the third region (30), whereby a height of a cooling fluid level of the cooling fluid (25) in the third region (30) of the cooling channel (24) can be set by means of the stagnation edge (56) in a radial direction (RR).

9. Rotor (10) according to one of the preceding claims, characterized in that the rotor (10) comprises at least one cooling element (22) which axially covers the star disk (18) on its outer side facing away from the laminated core (16), and has at least one cooling element cooling channel (58) by means of which cooling fluid (25) guided in the rotor shaft (14) is guided to an outer side (60) of the cooling element (22) facing away from the star disk (18). 24-0188 ABZ EXA 18.10.2024 can be made possible, allowing the cooling fluid (25) to flow onto this outer surface (60) of the heat sink (22).

10. Motor vehicle with an electrically excited synchronous machine comprising a stator and a rotor (10) rotatable relative to the stator about an axis of rotation according to one of the preceding claims. 24-0188 ABZ EXA 18.10.2024

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