Rotor for an electric machine

Abstract

The invention relates to a rotor (1) for an electric machine. The rotor (1) comprises a plurality of windings (4) and a plurality of slot wedges (6) arranged between the windings (4). Flow paths (14) are formed in the slot wedges (6), wherein in the flow paths (14) the cooling fluid flows around and cools the windings (4) directly.

Description

[0001] November 27, 2025

[0002] 1

[0003] Rotor for an electric machine

[0004] The invention relates to a rotor for an electric machine according to the preamble of claim 1.

[0005] A rotor for an electric machine, particularly a separately excited synchronous machine, typically comprises a shaft, a winding support, and several windings. The windings are wound on the winding support and arranged evenly around the shaft. Wedges are usually positioned between the windings to secure and partially compress them. These wedges reduce the rotor's air resistance and improve heat dissipation from the windings.

[0006] EP 2 985 885 A1 discloses sealing wedges with cavities filled with air. EP 2 807 726 B1 discloses sealing wedges with cavities through which a coolant can flow. US 8729 752 B2 discloses a sealing wedge with openings through which coolant is sprayed onto the inner walls of the sealing wedge. EP 1 317 048 B1 discloses a stator with sealing wedges in which cavities through which coolant can flow are formed.

[0007] The cavities in the sealing wedge allow for better cooling of the rotor windings. These cavities can, for example, be filled with a coolant, thus improving the cooling of the windings. However, the disadvantage is that heat is conducted through the sealing wedge and subsequently absorbed by the coolant, so the sealing wedge must have good thermal conductivity. A material with good thermal conductivity would be, for example, metal, which would then be used during rotor operation.

[0008] MAHLE internal restricted (CL2) November 27, 2025

[0009] 2. Disruptive eddy currents can form in the locking wedge. Furthermore, in this case, the locking wedge must be additionally insulated from the windings. A locking wedge made of plastic often has low thermal conductivity, thus reducing its cooling effect.

[0010] The object of the invention is therefore to provide an improved or at least alternative embodiment for a rotor of the generic type, in which the described disadvantages are overcome.

[0011] This problem is solved according to the invention by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

[0012] The present invention is based on the general idea of ​​providing a rotor with locking wedges with which the windings can be cooled directly, thereby improving the cooling effect, since the heat from the winding no longer has to be conducted through the wall of the locking wedge and, if necessary, an insulating paper.

[0013] The rotor according to the invention is designed or intended for an electric machine, in particular a separately excited synchronous machine. The rotor has a shaft rotatable about an axis of rotation and a winding carrier connected to the shaft in a rotationally fixed manner. Furthermore, the rotor has several axially aligned windings. The windings are wound in a circular direction around the axis of rotation and distributed on the winding carrier. The windings are spaced apart from each other in the circular direction, and thus an axially aligned slot is formed between each adjacent winding. The rotor also has several axially aligned locking wedges that engage between the

[0014] MAHLE internal restricted (CL2) November 27, 2025

[0015] 3

[0016] The rotor windings are arranged and the slots are closed. The rotor also has a cooling unit through which a coolant flows, with at least one flow path for cooling the windings. The at least one flow path is formed in one of the sealing wedges. According to the invention, the at least one flow path to the windings adjacent to the associated sealing wedge is at least partially open, so that the windings adjacent to the associated sealing wedge can be directly exposed to the coolant flowing in the at least one flow path and thus directly cooled.

[0017] In connection with the present invention, the terms "axial," "radial," and "rotating" always refer to the axis of rotation of the shaft. The term "radial" means that the respective element is oriented approximately axially, i.e., from a radially inner side of the rotor to a radially outer side of the rotor. Accordingly, the radial direction in connection with the present invention may deviate from the geometric radial direction. The term "axial" means that the respective element is oriented approximately axially, i.e., from one axial side of the rotor to another axial side of the rotor. Accordingly, the axial direction in connection with the present invention may deviate from the geometric axial direction.

[0018] In the rotor according to the invention, the windings are directly exposed to or surrounded by the cooling fluid, allowing the cooling fluid to directly absorb the waste heat from the windings. In other words, the heat exchange between the windings and the cooling fluid does not occur indirectly via the sealing wedge, but directly, and is therefore significantly improved and intensified. The material of the sealing wedge and its thermal conductivity play a subordinate role in the cooling of the windings. Consequently, the

[0019] MAHLE internal restricted (CL2) November 27, 2025

[0020] 4

[0021] The sealing wedge can also be made of, for example, plastic with low thermal conductivity, without impairing the cooling of the windings. Using a plastic sealing wedge can increase the efficiency of the rotor or the electric machine, as eddy currents cannot form within the wedge.

[0022] The flow path can be axially oriented and extend over the entire or nearly the entire axial length of the sealing wedge. This allows the windings adjacent to the sealing wedge to be cooled over their entire or nearly their entire axial length within the flow path. The cooling fluid can be dielectric or oil.

[0023] In one possible embodiment of the rotor, the cooling unit can have an axially oriented inlet channel and at least one radially oriented inlet opening. The inlet channel can be located in the shaft, and the at least one inlet opening can be formed partially in the shaft and partially in the winding carrier. Each flow path in the sealing wedge can then be fluidically connected to the inlet channel in the shaft via the at least one inlet opening.

[0024] In a possible alternative embodiment, the cooling unit can have an axially oriented inlet channel and at least one radially oriented inlet opening. The inlet channel can be located in the shaft, and the at least one inlet opening can be located partially in the shaft and partially in a base body of the rotor formed by a laminated core. Each flow path in the sealing wedge can then be fluidically connected to the inlet channel in the shaft via the at least one inlet opening.

[0025] MAHLE internal restricted (CL2) November 27, 2025

[0026] 5

[0027] The base body or the laminated core forming the base body can be made of a ferromagnetic material, in particular iron.

[0028] In both embodiments described above, the coolant can be introduced into the cooling unit via the inlet channel and then distributed into the respective flow path through the inlet opening. Since the rotor rotates during operation, the coolant can be displaced from the inlet channel into the inlet opening by centrifugal force and then flow radially outwards into the flow path. The resulting pressure then distributes the coolant within the flow path, allowing it to flow directly around the windings. The coolant can then be discharged radially outwards from the flow path, for example, via at least one outlet channel from the rotor. The outlet channel can advantageously be fluidically connected to the flow path.

[0029] In a possible alternative embodiment, the cooling unit can have at least one diffusion nozzle arranged at an axial longitudinal end of the rotor. This at least one diffusion nozzle can then be located axially spaced opposite at least one of the flow paths and fluidically connected to that flow path. In this embodiment, the coolant can be conveyed from a stator-side delivery device to the diffusion nozzle and then introduced into the flow path via the diffusion nozzle. The diffusion nozzle can, for example, be formed within a bearing shield.

[0030] In a possible alternative embodiment, the cooling unit can have an axially oriented inlet channel, at least one radially oriented inlet opening, and a collection chamber. The inlet channel and the

[0031] MAHLE internal restricted (CL2) November 27, 2025

[0032] 6. At least one inlet opening can be formed in the shaft. The collecting chamber can be formed axially between the windings and a retaining ring of the rotor. Each flow path in the sealing wedge can then be fluidically connected to the inlet channel via the collecting chamber and the at least one inlet opening.

[0033] In this embodiment, the coolant can be introduced into the cooling unit via the inlet channel and then guided through at least one inlet opening into the collection chamber, where it is collected. Since the rotor rotates during operation, the coolant can be displaced from the collection chamber into the respective flow path by the effect of centrifugal force and pressure. The resulting pressure then distributes the coolant within the flow path, allowing it to flow directly around the windings. After passing through the flow path, the coolant can flow out of the rotor via a further collection chamber. This additional collection chamber can be configured axially between the windings and another mounting ring of the rotor, analogous to the collection chamber already described.

[0034] In one possible embodiment of the flow path, the at least one flow path can be formed by an axially oriented flow chamber and several openings oriented in the direction of rotation. The flow chamber can be located inside the sealing wedge, and each opening can lead from the flow chamber through the sealing wedge to the winding adjacent to the sealing wedge. The openings can be arranged axially offset from one another in at least two rows. Then, in at least one of the rows, the openings can lead from the flow chamber to one winding adjacent to the sealing wedge, and in at least one of the other rows, from the flow chamber to the other winding adjacent to the sealing wedge.

[0035] MAHLE internal restricted (CL2) November 27, 2025

[0036] 7. This advantageously allows both windings adjacent to the locking wedge to be cooled.

[0037] In this embodiment of the flow path, the coolant can enter the flow chamber at one axial end of the sealing wedge and exit the flow chamber at another axial end. Within the flow chamber, the coolant can flow along the axially aligned inner walls of the sealing wedge, which are in contact with the adjacent windings, thereby flowing directly around the windings. The openings can advantageously be formed in and penetrate these inner walls facing the windings. This allows the windings to be almost completely flooded with the coolant and thus cooled intensively.

[0038] In another possible embodiment of the flow path, the at least one flow path can be formed by an axially oriented distribution channel, at least one axially oriented collector channel, and several connecting channels oriented transversely to the axis of rotation. The distribution channel can be radially internal, and all collector channels radially external, within the sealing wedge. The distribution channel and all collector channels can then be fluidically connected to each other via the connecting channels. The connecting channel can be open at one end to one of the windings adjacent to the sealing wedge and, transversely to the direction of rotation, partially bounded to the outside by this winding, thereby closing it. In this embodiment, the coolant can be guided precisely along the winding, thus providing intensive cooling of the winding.

[0039] The distribution channel can be located on an outer surface of the locking wedge that is axially aligned and facing the shaft, as an axial

[0040] MAHLE internal restricted (CL2) November 27, 2025

[0041] The distribution channel can be formed with an 8-point aligned groove or slot. The winding carrier can then be partially enclosed and thus partially bounded to the outside. In other words, the connecting channel can be bounded on one side by the sealing wedge and on the other side by the winding carrier. With this design of the distribution channel, the winding carrier can also be directly exposed to the flow of coolant and thus be intensively cooled. Furthermore, the distribution channel can be simplified to a groove.

[0042] The connecting channel can, for example, be formed as a groove or slot oriented transversely to the axis of rotation on an outer surface of the sealing wedge that is axially aligned and facing the winding adjacent to the sealing wedge. Several connecting channels can be formed on the surface of the sealing wedge in the form of parallel grooves. These connecting channels can thus connect the distribution channel to the collector channel over the entire or nearly the entire axial length of the sealing wedge. This allows the winding to be cooled directly over its entire or nearly its entire axial length. Furthermore, the connecting channels can be simplified to simple grooves.

[0043] The collector channel can be formed as an axially oriented groove or slot on an outer surface of the locking wedge, which is axially aligned and faces the winding adjacent to the locking wedge. The collector channel can then be partially bounded and thus closed off by the adjacent winding. With this design of the collector channel, the winding can also be cooled by flow within the collector channel. Furthermore, the collector channel in the form of a groove can be simplified.

[0044] MAHLE internal restricted (CL2) November 27, 2025

[0045] 9. Alternatively, the collector channel can be formed by an axially oriented channel located within the sealing wedge. The collector channel can then be fluidically connected to the individual connecting channels by a bore oriented transversely to the axis of rotation. With this design of the collector channel, the coolant can be reliably collected in the collector channel and discharged from the flow path.

[0046] In this embodiment of the flow path, the distribution channel can be fluidically connected to the inlet channel described above via one or more inlet openings. The distribution channel can be fluidically connected to the inlet channel at one axial end of the sealing wedge or at both ends of the sealing wedge via the inlet openings. From the inlet channel, the coolant can enter the distribution channel via the inlet opening under the influence of centrifugal force and be distributed from the distribution channel into the connecting channels. In the connecting channel, the coolant can then flow between the outer surface of the sealing wedge and the winding to the collector channel under the influence of centrifugal force. In doing so, the coolant can directly flow around or act upon the adjacent winding, thus cooling it.The coolant can be collected in the collector channel and flow out of the collector channel, for example via drain channels, at one axial end of the sealing wedge or at both ends of the sealing wedge.

[0047] In order to cool both windings adjacent to the sealing wedge, at least one flow path can have two axially aligned collector channels. The collector channels can be located on axially aligned surfaces of the sealing wedge that are opposite each other and face the windings adjacent to the sealing wedge.

[0048] MAHLE internal restricted (CL2) November 27, 2025

[0049] 10. The connecting channels can then be formed on the two opposing surfaces of the sealing wedge and fluidically connect the distributor channel to the two collector channels. In particular, several connecting channels can be formed axially one above the other over the entire or nearly the entire axial length of the surface, and thus the winding can be directly surrounded and cooled by the coolant over its entire or nearly its entire axial length.

[0050] In another possible embodiment of the flow path, the at least one flow path can have at least two axially aligned connecting channels. These connecting channels can be formed on opposing outer surfaces of the sealing wedge, which are axially aligned and facing the windings adjacent to the sealing wedge. Each connecting channel can then be open on one side to one of the windings adjacent to the sealing wedge and be partially bounded and thus closed off by this winding transversely to the direction of rotation. The respective connecting channel can, in particular, be designed as an axially aligned groove open to the respective adjacent winding. In this embodiment, the cooling fluid can be guided precisely along the winding, thereby providing intensive cooling.

[0051] In this embodiment, the locking wedge can additionally have at least one rib oriented transversely to the axis of rotation on at least one of its outer surfaces. This rib can interrupt or bridge the respective connecting channels formed on the surface. This allows the width of the respective connecting channel to be maintained along its entire axial length.

[0052] MAHLE internal restricted (CL2) November 27, 2025

[0053] 11

[0054] In another possible embodiment of the flow path, the at least one flow path can have at least one axially oriented flow chamber. The at least one flow chamber can be formed on an outer surface of the sealing wedge that is axially oriented and faces one of the windings adjacent to the sealing wedge. The flow chamber can be open to the winding adjacent to the sealing wedge. Preferably, the at least one flow path can have two axially oriented flow chambers. The flow chambers can be formed on opposing outer surfaces of the sealing wedge that are axially oriented and face the windings adjacent to the sealing wedge. The flow chambers can be open to the windings adjacent to the sealing wedge.In other words, the flow chambers can be bounded on one side, transverse to the direction of rotation, by the outer surfaces of the sealing wedge and on the other side by the windings adjacent to the sealing wedge. This allows the windings adjacent to the sealing wedge to be directly exposed to the coolant flowing in the at least one flow path and thus cooled directly.

[0055] Furthermore, if the sealing wedge has one or more cavities in the axial direction within its interior, these need not be part of the flow path. Such cavities, which do not need to be permeable to the coolant, can be advantageous or necessary for manufacturing the wedge, for example, using injection molding.

[0056] In this embodiment, the locking wedge can have several projections formed on its outer surfaces. These projections can extend from the outer surfaces transversely to the

[0057] MAHLE internal restricted (CL2) November 27, 2025

[0058] 12

[0059] The projections extend beyond the axis of rotation. They can project into the flow chambers and abut the windings adjacent to the sealing wedge. In other words, the projections can support the windings adjacent to the sealing wedge, ensuring that the height of the flow chambers, defined perpendicular to the axis of rotation, remains constant or at least nearly constant. This allows for better flow through the flow chambers and, consequently, more intensive cooling of the adjacent windings.

[0060] The projections on the respective outer surface can be axially and / or radially offset from one another. This allows adjacent windings to be supported over the entire axial and / or radial extent of the flow chambers. The projections can divide the flow path within the flow chambers into several labyrinthine sub-paths. The deflection or offset of the projections ensures that each winding is supported by individual projections at sufficiently short intervals, thereby keeping the flow chamber between the sealing wedge and the windings open to a sufficient height. Furthermore, the deflection of the coolant within the flow chambers allows for better and more intensive cooling of the windings.

[0061] The projections can each be designed in the form of an elongated rib. For example, the height of each rib, defined perpendicular to the axis of rotation, can be approximately 2 mm, and the length of each rib, defined along its outer surface, can be approximately 3.5 mm to 4 mm. With this design, the projections can be oriented at an angle to the axis of rotation in order to support several turns of the adjacent winding. Alternatively or additionally, the projections can be attached to the

[0062] MAHLE internal restricted (CL2) November 27, 2025

[0063] 13. The respective outer surfaces, viewed along the axis of rotation, are arranged at least sectionally one above the other. This allows the adjacent windings to be supported over the entire axial extent of the flow chambers.

[0064] As described above, the projections are designed to support the adjacent windings and can, in principle, also have other suitable shapes. For example, the projections can be cylindrical or frustoconical.

[0065] Further important features and advantages of the invention will become apparent from the dependent claims, the drawings and the associated description of the figures based on the drawings.

[0066] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0067] Preferred embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein identical reference numerals refer to identical or similar or functionally identical components.

[0068] They show, schematically, each one

[0069] Fig. 1 shows a sectional view of a rotor according to the invention with locking wedges in a first embodiment with a first flow scheme;

[0070] MAHLE internal restricted (CL2) November 27, 2025

[0071] 14

[0072] Fig. 2 shows a sectional view of the rotor according to the invention with locking wedges in the first embodiment with a second flow scheme;

[0073] Fig. 3 shows a sectional view of the rotor according to the invention with locking wedges in the first embodiment with a third flow scheme;

[0074] Fig. 4 shows a sectional view of the rotor according to the invention with locking wedges in a sixth embodiment with a fourth flow scheme;

[0075] Fig. 5 shows a view of the locking wedge in the first embodiment;

[0076] Fig. 6 shows a view of the locking wedge in a second embodiment;

[0077] Fig. 7 shows a sectional view of the rotor according to the invention with the locking wedges in a third embodiment;

[0078] Fig. 8 shows a view of the locking wedge in the third embodiment;

[0079] Fig. 9 shows a partial sectional view of the rotor according to the invention with the locking wedge in a fourth embodiment;

[0080] Fig. 10 shows a view of the locking wedge in a fifth embodiment;

[0081] Fig. 11 shows a partial sectional view of the rotor according to the invention with the locking wedge in the fifth embodiment;

[0082] MAHLE internal restricted (CL2) November 27, 2025

[0083] 15

[0084] Fig. 12 shows a view of the locking wedge in the sixth embodiment;

[0085] Fig. 13 shows a radial sectional view of the rotor according to the invention with the

[0086] Locking wedge in the sixth embodiment;

[0087] Fig. 14 shows an axial sectional view of the rotor according to the invention with the locking wedge in the sixth embodiment;

[0088] Fig. 15 shows a top view of the rotor according to the invention with the locking wedge in the sixth embodiment.

[0089] Fig. 1 shows a sectional view of a rotor 1 according to the invention for an electric machine, in particular for a separately excited synchronous machine. In a first embodiment, the rotor 1 comprises a shaft 2, a winding carrier 3, several windings 4, two retaining rings 5, and several locking wedges 6. In total, the rotor here has eight windings 4 and eight locking wedges 6, of which only some are visible in Fig. 1.

[0090] The shaft 2 is rotatable about an axis of rotation RA, and the winding carrier 3 is rotationally fixed to the shaft 2. The winding carrier 3 comprises a base body 7 designed as a laminated core and two end caps 8, with the base body 7 arranged axially between the end caps 8. Several—here a total of eight—radially outwardly directed support teeth 9 are formed on the winding carrier 3, which are evenly distributed around the axis of rotation RA and in a direction of rotation UR around the axis of rotation RA. The windings 4 are wound around the support teeth 9, with each winding 4 consisting of several turns of an electrically conductive wire or copper wire. The individual windings 4 extend

[0091] MAHLE internal restricted (CL2) November 27, 2025

[0092] 16 windings are mostly axially aligned, with the exception of winding heads, and are spaced apart from each other in the direction of rotation UR. Between the windings 4 adjacent in the direction of rotation UR, several – here a total of eight – axially aligned grooves 10 are formed. The locking wedges 6 are arranged in the grooves 10 and close them. The retaining rings 5 ​​enclose the winding carrier 3 or the end caps 8 of the winding carrier 3 from the outside and hold them together.

[0093] The rotor 1 also has a cooling unit 11 through which a cooling fluid – for example, oil – flows for cooling the windings 4. The cooling unit 11 comprises an inlet channel 12, several – here sixteen – inlet openings 13, several – here eight – flow paths 14 and several – here sixteen – outlet channels 15.

[0094] Figure 1 shows the rotor 1 with a first flow diagram. The inlet channel 12 is closed at one end in the shaft 2 and axially aligned. The flow paths 14 are formed in the sealing wedges 6, with each sealing wedge 6 having a single flow path 14. The flow path 14 in the sealing wedge 6 is fluidically connected to the inlet channel 12 in the shaft 2 via two inlet openings 13. The inlet openings 13 are arranged at opposite axial ends 6a and 6b of the sealing wedge 6. The inlet openings 13 extend radially outwards from the inlet channel 12 into the flow path 14 and are formed partly in the shaft 2 and partly in the winding carrier 3. Each flow path 14 also has two outlet channels 15. The drainage channels 15 are formed in the retaining rings 5 ​​and directed radially outwards.The drainage channels 15 are located at the opposite axial ends 6a and 6b of the sealing wedge 6 and are fluidically connected to the flow path 14.

[0095] MAHLE internal restricted (CL2) November 27, 2025

[0096] 17

[0097] Fig. 2 shows a sectional view of the rotor 1 according to the invention with locking wedges 6 in the first embodiment with a second flow pattern. In contrast to the first flow pattern in Fig. 1, here the inlet openings 12 are formed partly in the shaft 2 and partly in the base body 7 or the laminated core of the rotor 1. Each flow path 14 is assigned one inlet opening 12. The respective inlet opening 12 opens approximately centrally into the respective distribution channel 16 of the flow path 14. Otherwise, the first and second flow patterns of the rotor 1 are identical.

[0098] Fig. 3 shows a sectional view of the rotor 1 according to the invention with sealing wedges 6 in the first embodiment with a third flow scheme. In contrast to the first and second flow schemes, here the coolant is supplied to the respective sealing wedge 6 at the respective axial end 6a. For this purpose, the coolant can be sprayed onto the respective sealing wedge 6 via a dispersion nozzle – not shown here – which is formed, for example, in a bearing housing. The coolant is then supplied directly into the distribution channel 19 of the flow path 14. Otherwise, the third and the first / second flow schemes of the rotor 1 are identical.

[0099] Fig. 4 shows a sectional view of the rotor 1 according to the invention with the locking wedges 6 in a sixth embodiment with a fourth flow scheme. Here, the cooling unit 11 comprises the axial inlet channel 12 formed in the shaft 2, the radial inlet openings 13 formed in the shaft 2, and the flow paths 14 formed in the locking wedges 6. Furthermore, the cooling unit 11 comprises two collecting chambers 24, which are axially located between the retaining rings 5 ​​of the rotor 1 and the windings.

[0100] MAHLE internal restricted (CL2) November 27, 2025

[0101] 18

[0102] 4 are formed at the axially opposite ends 6a and 6b of the sealing wedges 6. One collecting chamber 24 is fluidically arranged between the inlet openings 13 and the flow paths 14, and the other collecting chamber 24 is fluidically arranged downstream of the flow paths 14.

[0103] Fig. 5 shows a view of the sealing wedge 6 in the first embodiment. In the first embodiment, the single flow path 14 in the sealing wedge 6 comprises an axially oriented distributor channel 16, two axially oriented collector channels 17, and several radially oriented connecting channels 18.

[0104] The distribution channel 16 is radially internal, and the collector channels 17 are radially external, within the sealing wedge 6. The distribution channel 16 is formed as a groove or slot on an external surface 19a of the sealing wedge 6. Referring to Fig. 1, the surface 19a is axially aligned and facing the shaft 2. The distribution channel 16 is closed or bounded on one side within the rotor 1 by the sealing wedge 6 and on the other side by the winding carrier 3 or the base body 7 of the winding carrier 3, and is fluidically connected to the inlet channel 12 on both sides via the inlet openings 13.

[0105] The collector channels 17 are formed within the sealing wedge 6 as internal channels adjacent to two opposing external surfaces 19b of the sealing wedge 6. Referring to Fig. 1, the surfaces 19b are axially aligned and facing the adjacent windings 4. The collector channels 17 are fluidically connected axially on both sides to the discharge channels 15.

[0106] The connecting channels 18 are radially oriented and connect the distribution channel 16 with the two collector channels 17. The connecting channels 18

[0107] MAHLE internal restricted (CL2) November 27, 2025

[0108] The connecting channels 19 are arranged axially one above the other and parallel to each other on the outer surfaces 19b of the locking wedge 6, almost completely covering both surfaces 19b of the locking wedge 6. Each connecting channel 18 is formed as a groove or slot on the surface 19b. The connecting channel 18 opens into the distributor channel 16 on one side and into the collector channel 17 via a bore 20 on the other. Referring to Fig. 1, the connecting channels 18 are arranged in the rotor 1 facing the windings 4 and are partially bounded to the outside by the windings 4, thus closing them transversely to the direction of rotation UR.

[0109] Referring to Fig. 1, the coolant in the cooling unit 11 flows through the rotor 1 under the influence of centrifugal force as the rotor 1 rotates, thereby cooling in particular the windings 4 of the rotor 1. In Fig. 1, the flow of the coolant is indicated by arrows. First, the coolant flows into the inlet channel 12 and is distributed axially within it. From the inlet channel 12, the coolant flows radially outwards through the inlet openings 13 under the influence of centrifugal force into the distribution channels 16 of the individual flow paths 14. In each distribution channel 16, the coolant is distributed axially and flows radially outwards through the connecting channels 18 into the collector channels 17 under the influence of centrifugal force. From the collector channels 17, the coolant then flows out of the rotor 1 through the outlet channels 15.

[0110] Fig. 6 shows a view of the locking wedge 6 in a second embodiment. In the second embodiment of the locking wedge 6, the collector channels 17 are formed on the surfaces 19b of the locking wedge 6 in the form of grooves or slots. If the locking wedge 6 is installed in the rotor 1, the collector channels 17 are closed on one side by the adjacent winding 4.

[0111] MAHLE internal restricted (CL2) November 27, 2025

[0112] 20

[0113] Otherwise, the first embodiment and the second embodiment of the locking wedge 6 are identical.

[0114] Fig. 7 shows a sectional view of the rotor 1 according to the invention with the sealing wedge 6 in a third embodiment. Fig. 8 shows a view of the sealing wedge 6 in the third embodiment. In the third embodiment, the flow path 14 in the sealing wedge 6 has an axially oriented flow chamber 21 with several openings 22 oriented in the direction of rotation UR. The flow chamber 21 is formed internally within the sealing wedge 6, and the openings 22 lead from the flow chamber 21 through the sealing wedge 6 to the adjacent windings 4. Referring to Fig. 7, the openings 22 are closed on one side by the windings 4, so that the cooling fluid flowing in the flow chamber 21 can flow directly around the windings 4.

[0115] Fig. 9 shows a partial sectional view of the rotor 1 according to the invention with the locking wedge 6 in a fourth embodiment. In the fourth embodiment, the flow chamber 21 is radially wider than in the third embodiment. The openings 22 also have a greater radial width compared to the third embodiment. As a result, the windings 4 are exposed to the cooling fluid over a larger area and can be cooled more intensively.

[0116] Fig. 10 shows a view of the sealing wedge 6 in a fifth embodiment. In the fifth embodiment, the flow path 14 has axially aligned connecting channels 18. No distributor channel 16 and no collector channel 17 are provided. Furthermore, the sealing wedge 6 has several webs 23 on its outer surfaces 19b, oriented transversely to the axis of rotation RA, which bridge the respective connecting channels 18.

[0117] MAHLE internal restricted (CL2) November 27, 2025

[0118] 21

[0119] Fig. 11 shows a partial sectional view of the rotor 1 according to the invention with the locking wedge 6 in the fifth embodiment. Here it is particularly evident that the connecting channels 18 are designed as slots or grooves open to the windings 4, so that the cooling fluid flowing in the flow path 14 can directly flow around and cool the windings 4.

[0120] Fig. 12 shows a view of the sealing wedge 6 in the sixth embodiment. This embodiment is already shown in Fig. 4. In the sixth embodiment, the flow path 14 comprises two axially aligned flow chambers 25 formed on the surfaces 19b of the sealing wedge 6. The flow chambers 25 are open to the adjacent windings 4, as can be seen particularly in Figs. 14 and 15. The sealing wedge 6 includes several projections 26 that extend from the surfaces 19b transversely to the axis of rotation RA into the flow chambers 25.

[0121] Fig. 13 shows a radial sectional view of the rotor 1 according to the invention with the locking wedge 6 in the sixth embodiment, through one of the flow chambers 25. As can be seen particularly well in Fig. 13, the projections 26 are designed as elongated ribs and are oriented at an inclination angle NW to the axis of rotation RA. The inclination angle NW is in particular greater than 0° and less than 90°. Furthermore, the projections 26 are spaced axially and radially apart from one another and are offset. It can also be seen that the projections 26 are arranged section by section one above the other or overlapping when viewed along and transversely to the axis of rotation RA. This supports the winding 4 over its entire radial and axial extent transversely to the axis of rotation RA, so that

[0122] MAHLE internal restricted (CL2) November 27, 2025

[0123] 22 the flow chamber 25 between the sealing wedge 6 and the windings 4 remains permeable. The projections 26 divide the flow path 14 within the flow chambers 25 into several labyrinthine partial flow paths 27 – only two of which are indicated here by arrows as examples.

[0124] Fig. 14 shows an axial sectional view and Fig. 15 shows a top view of the rotor 1 according to the invention with the locking wedge 6 in the sixth embodiment. As can be seen in Figs. 14 and 15, the projections 26 abut the adjacent windings 4 in the direction of rotation UR or transversely to the axis of rotation RA, so that the windings 4 are supported by the projections 26. This ensures that the height of the flow chambers 25, defined transversely to the axis of rotation RA, is maintained over their entire radial and axial extent. Furthermore, it can be seen in Figs. 14 and 15 that the flow chambers 25 are open to the adjacent windings 4.

[0125] In summary, as the coolant flows through the flow paths 14 formed in the sealing wedges 6, it directly surrounds the windings 4. This allows the windings 4 to exchange heat directly with the coolant and thus be cooled. In particular, the heat exchange between the coolant and the windings 4 does not occur via the material of the sealing wedge 6, thereby improving and intensifying the cooling of the windings 4.

[0126] *****

[0127] MAHLE internal restricted (CL2)

Claims

November 27, 2025 23 Claims 1. Rotor (1 ) for an electric machine, - wherein the rotor (1 ) has a shaft (2) rotatable about an axis of rotation (RA) and a winding carrier (3) rotatably connected to the shaft (2), - wherein the rotor (1 ) has several axially aligned windings (4) and the windings (4) are wound in a direction of rotation (UR) around the axis of rotation (RA) distributed on the winding carrier (3), - wherein the windings (4) are spaced apart from each other in the direction of rotation (UR) and thereby an axially oriented groove (10) is formed between the adjacent windings (4), - wherein the rotor (1 ) has several axially aligned locking wedges (6) and the locking wedges (6) are arranged between the windings (4) and close the slots (10), and - that the rotor (1 ) has a cooling unit (11 ) through which a cooling fluid flows, with at least one flow path (14) for cooling the windings (4), and the at least one flow path (14) is formed in one of the sealing wedges (6), characterized in that the at least one flow path (14) to the windings (4) adjacent to the associated sealing wedge (6) is at least partially open, so that the windings (4) adjacent to the sealing wedge (6) can be directly exposed to the cooling fluid flowing in the at least one flow path (14) and thus be directly cooled.

2. Rotor (1) according to claim 1, LE internal restricted (CL2) November 27, 2025 24 characterized by this, - that the cooling unit (11 ) has an axially oriented inlet channel (12) and at least one radially oriented inlet opening (13), - that the inlet channel (12) is formed in the shaft (2) and the at least one inlet opening (13) is formed partly in the shaft (2) and partly in the winding carrier (3), and - that each flow path (14) in the sealing wedge (6) is fluidically connected to the inlet channel (12) in the shaft (2) via the at least one inlet opening (13).

3. Rotor (1) according to claim 1, characterized in that, - that the cooling unit (11 ) has an axially oriented inlet channel (12) and at least one radially oriented inlet opening (13), - that the inlet channel (12) is formed in the shaft (2) and the at least one inlet opening (13) is formed partly in the shaft (2) and partly in a base body (7) of the rotor (1) formed by a laminated core, and - that each flow path (14) in the sealing wedge (6) is fluidically connected to the inlet channel (12) in the shaft (2) via the at least one inlet opening (13).

4. Rotor (1) according to claim 1, characterized in that, - that the cooling unit (11 ) has a dispersion nozzle arranged at an axial longitudinal end of the rotor (1 ), and - that the at least one dispersion nozzle is axially spaced opposite at least one of the flow paths (14) and is fluidically connected to the at least one flow path (14). LE internal restricted (CL2) November 27, 2025 25 5. Rotor (1) according to claim 1, characterized in that, - that the cooling unit (11 ) has an axially oriented inlet channel (12), at least one radially oriented inlet opening (13) and a collection chamber (24), - that the inlet channel (12) and the at least one inlet opening (13) are formed in the shaft (2) and the collecting space (24) between the windings (4) and a retaining ring (5) of the rotor (1), and - that each flow path (14) in the sealing wedge (6) is fluidically connected to the inlet channel (12) via the collection chamber (24) and the at least one inlet opening (13).

6. Rotor (1 ) according to one of claims 1 to 5, characterized in that, - that at least one flow path (14) is formed through an axially oriented flow space (21) and several openings (22) oriented in the direction of rotation (UR), and - that the flow chamber (21 ) is formed inside the sealing wedge (6) and the respective opening (22) leads from the flow chamber (21 ) through the sealing wedge (6) to the winding (4) adjacent to the sealing wedge (6).

7. Rotor (1) according to claim 6, characterized in that the openings (22) are arranged axially offset from each other in at least two rows, wherein the openings (22) in at least one of the rows are from the flow space (21) to the winding (4) adjacent to the locking wedge (6) and the openings (22) in at least one of the other rows are from LE internal restricted (CL2) November 27, 2025 26 lead from the flow space (21) to the other winding (4) adjacent to the locking wedge (6).

8. Rotor (1 ) according to one of claims 1 to 5, characterized in that, - that the at least one flow path (14) is formed by an axially oriented distribution channel (16) and at least one axially oriented collector channel (17) and several connecting channels (18) oriented transversely to the axis of rotation (RA), - that the distribution channel (16) is radially internal and all collector channels (17) are radially external in the sealing wedge (6) and are fluidically connected to each other via the connecting channels (18), and - that the connecting channel (18) is open on one side to one of the windings (4) adjacent to the locking wedge (6) and is partially bounded to the outside by this winding (4) transversely to the direction of rotation (UR) and is thereby closed.

9. Rotor (1 ) according to claim 8, characterized in that the connecting channel (18) is formed on an outer surface (19b) of the locking wedge (6), which is axially aligned and facing the winding (4) adjacent to the locking wedge (6), as a groove oriented transversely to the axis of rotation (RA).

10. Rotor (1 ) according to claim 8 or 9, characterized in that, - that the collector channel (17) is located on an outer surface (19b) of the sealing wedge (6), which is axially aligned and which is restricted to the LE internal (CL2) November 27, 2025 27 The locking wedge (6) is facing the adjacent winding (4) and is formed as an axially oriented groove, and - that the collector channel (17) is partially limited to the outside by the adjacent winding (4) and is therefore closed.

11. Rotor (1) according to claim 8 or 9, characterized in that, - that the collector channel (17) is formed by an axially oriented channel located within the sealing wedge (6), and - that the collector channel (17) is fluidically connected to the individual connecting channels (18) by a bore (20) oriented transversely to the axis of rotation (RA).

12. Rotor (1) according to one of claims 8 to 11, characterized in that, - that the distribution channel (16) is formed as an axially oriented groove on an outer surface (19a) of the locking wedge (6), which is axially oriented and facing the shaft (2), and - that the distribution channel (16) is partially limited to the outside by the winding carrier (3) and is therefore closed.

13. Rotor (1 ) according to one of claims 8 to 12, characterized in that, - that the at least one flow path (14) has two axially aligned collector channels (17) and the collector channels (17) are formed on opposing outer surfaces (19b) of the sealing wedge (6), which are axially aligned and facing the windings (4) adjacent to the sealing wedge (6), and LE internal restricted (CL2) November 27, 2025 28 - that the connecting channels (18) are formed on both outer surfaces (19b) and fluidically connect the distribution channel (16) with the two collector channels (17).

14. Rotor (1 ) according to one of claims 1 to 5, characterized in that, - that the at least one flow path (14) has at least two axially aligned connecting channels (18) and that the connecting channels (18) are formed on opposing outer surfaces (19b) of the sealing wedge (6), which are axially aligned and facing the windings (4) adjacent to the sealing wedge (6), and - that each connecting channel (18) is open on one side to one of the windings (4) adjacent to the locking wedge (6) and is partially bounded to the outside by this winding (4) transversely to the direction of rotation (UM) and is thereby closed.

15. Rotor (1 ) according to claim 14, characterized in that, - that the locking wedge (6) has at least one rib (23) oriented transversely to the axis of rotation (RA) on at least one of the outer surfaces (19b), and - that the bridge (23) interrupts or bridges the respective connecting channels (18) formed on the surface (19b).

16. Rotor (1 ) according to one of claims 1 to 5, characterized in that, - that at least one flow path (14) has two axially aligned flow chambers (25), LE internal restricted (CL2) November 27, 2025 29 - that the flow chambers (25) are formed on opposing outer surfaces (19b) of the sealing wedge (6), which are axially aligned and facing the windings (4) adjacent to the sealing wedge (6), and - that the flow chambers (25) are open to the windings (4) adjacent to the locking wedge (6).

17. Rotor (1 ) according to claim 16, characterized in that, - that the locking wedge (6) has several projections (26) formed on the outer surfaces (19b) and the projections (26) extend from the outer surfaces (19b) transversely to the axis of rotation (RA), and - that the projections (26) extend into the flow chambers (25) and are in contact with the windings (4) adjacent to the sealing wedge (6).

18. Rotor (1 ) according to claim 17, characterized in that, - that the projections (26) are each formed in the form of an elongated rib, and / or - that the projections (26) on the respective outer surface (19b) are axially and / or radially offset from each other, and / or - that the projections (26) on the respective outer surface (19b) are axially and / or radially spaced apart from each other, and / or - that the projections (26) are each formed in the form of an elongated rib and are oriented at an angle of inclination (NW) to the axis of rotation (RA), and / or LE internal restricted (CL2) November 27, 2025 30 - that the projections (26) are each formed in the form of an elongated rib and are arranged at least sectionally one above the other on the respective outer surface (19b) along the axis of rotation (RA), and / or - that the projections (26) divide the flow path (14) within the respective flow chamber (25) into several labyrinthine sub-flow paths (27). LE internal restricted (CL2)

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