Rotor

Abstract

The invention relates to a rotor (1) for an electric machine, in particular for a separately excited synchronous machine. The rotor (1) comprises a shaft (2), a winding carrier (3) having a plurality of windings (4), and a plurality of closure wedges (6) arranged between the windings (4). At least one of the closure wedges (6) comprises at least two wedge pieces (19a, 19b) which are integrally and / or interlockingly connected to one another to form the closure wedge (6). A flow path (16) is formed in the closure wedge (6), said flow path being at least partially open to the windings (4) adjacent to the closure wedge (6).

Description

[0001] December 16, 2025

[0002] 1

[0003] rotor

[0004] The invention relates to a rotor for an electric machine, in particular for a separately excited synchronous 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 carrier, and several windings. The windings are wound on the winding carrier and arranged around the shaft. Wedges are positioned between the windings, securing and partially compressing them. These wedges reduce the rotor's air resistance and improve heat dissipation from the windings. Cooling channels can also be incorporated into the wedges to cool the windings.

[0006] DE 102019 212 391 A1 discloses a rotor with foldable locking wedges. Each locking wedge has an internal, flow-through cooling channel.

[0007] EP 2 807 726 B1 discloses a rotor with V-shaped locking wedges. The respective locking wedge is arranged in the rotor between windings and closed on one side with a separate locking element, thereby forming a flow-through cooling channel.

[0008] US 7,061,154 discloses a rotor with a slotted locking wedge. The slotted locking wedge has several openings through which a liquid binder can enter the winding area during rotor manufacturing.

[0009] MAHLE internal restricted (CL2) December 16, 2025

[0010] 2

[0011] US Patent 8,729,752 B2 discloses a rotor with a locking wedge that has a central cooling channel. A coolant flows in the cooling channel and is sprayed onto the outer walls of the locking wedge.

[0012] 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.

[0013] This problem is solved according to the invention by the subject matter of independent claim 1. Advantageous embodiments are the subject matter of the dependent claims.

[0014] The rotor according to the invention is designed for an electric machine, in particular for 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. The rotor further comprises several axially aligned windings, which are wound on the winding carrier in a direction of rotation around the axis of rotation. The windings are spaced apart from each other in the direction of rotation, and thus an axially aligned groove is formed between each adjacent winding. The rotor also comprises several axially aligned locking wedges, which are arranged between the windings and close the grooves. At least one of the locking wedges has at least two separate wedge sections, wherein the wedge sections are connected to each other to form the locking wedge by a material bond and / or a form-fit connection.The at least one sealing wedge also includes a flow path through which a cooling fluid can flow, which is at least partially open to the windings adjacent to the sealing wedge.

[0015] MAHLE internal restricted (CL2) December 16, 2025

[0016] 3

[0017] In the rotor according to the invention, the flow path of the at least one sealing wedge to the adjacent windings is at least partially open, so that the windings can be directly exposed to or surrounded by the coolant. This allows the coolant to directly absorb the waste heat from the windings, and the windings can be cooled more intensively, effectively, or rapidly. In other words, the heat transfer between the windings and the coolant does not occur indirectly via the sealing wedge material, but directly, and can therefore be significantly improved or intensified. The at least two-part construction of the sealing wedge simplifies the implementation of different flow path geometries adapted to the cooling of the windings. The coolant can, in particular, be dielectric.The coolant can be, in particular, an oil.

[0018] The at least two wedge sections of the at least one locking wedge can be formed from plastic, preferably a thermoplastic, using a primary forming process, for example, injection molding. The at least two wedge sections of the at least one locking wedge can be materially bonded to the at least one locking wedge, in particular by welding, soldering, or bonding. The at least two wedge sections of the at least one locking wedge can, in particular, be identical to each other.

[0019] The at least two wedge pieces of the at least one locking wedge can be positively connected to one another, in particular by a plug connection, snap connection, or rivet connection, and thereby secured against radial and / or axial displacement relative to each other. The positive-locking connection of the wedge pieces of the at least one

[0020] MAHLE internal restricted (CL2) December 16, 2025

[0021] 4

[0022] The locking wedges can be connected, for example, by a pin-and-pocket connection and / or by a tongue-and-groove connection.

[0023] The at least one locking wedge can have exactly two wedge pieces. The two wedge pieces can then be materially bonded to the at least one locking wedge along a connection plane oriented radially to the axis of rotation and passing through the longitudinal center axis of the at least one locking wedge, in particular by welding or bonding or – especially in the case of wedge pieces made of metallic materials – also by soldering.

[0024] The at least one locking wedge can additionally have at least one stiffening element. The at least one stiffening element can be arranged radially outside the wedge sections of the at least one locking wedge and positively connected to the wedge sections of the at least one locking wedge. The stiffening element can be made of a different material than the wedge sections. In particular, the stiffening element can be made of metal or sheet metal. The stiffening element can increase the stiffness of the at least one locking wedge, especially in the radial direction. This can then also enable a higher operating speed of the rotor.

[0025] The at least one sealing wedge can have two axially aligned surfaces facing the winding adjacent to the at least one sealing wedge. The flow path of the at least one sealing wedge can also have at least two axially aligned connecting channels. At least one of the connecting channels of the flow path can then be formed on each surface of the at least one sealing wedge. The connecting channel of the flow path

[0026] MAHLE internal restricted (CL2) December 16, 2025

[0027] 5 can in particular be configured as at least one axially oriented groove on the surface of the at least one sealing wedge. Each connecting channel of the flow path can then be open on one side to the winding adjacent to the at least one sealing wedge and be bounded to the outside by this winding and thus closed. In the flow path of the at least one sealing wedge, the connecting channels can be configured over the entire axial length of the surface of the sealing wedge, and thus the winding can be directly surrounded and cooled by the cooling fluid flowing in the flow path over its entire or nearly its entire axial length.

[0028] The at least one sealing wedge can have at least two webs oriented transversely to the direction of rotation. At least one of these webs can be formed on each surface of the sealing wedge. The webs can bridge the respective connecting channels of the flow path formed on the surface of the at least one sealing wedge. If several webs are formed on the surface, they can be axially spaced apart from each other. In particular, the at least one sealing wedge can have at least four webs oriented transversely to the direction of rotation. At least two of these webs can then be axially spaced apart from each other on each surface of the sealing wedge. This allows the respective windings adjacent to the sealing wedge to be supported on the webs in the direction of rotation, and the cross-sectional area of ​​the connecting channel of the flow path to remain unobstructed over the entire axial length of the at least one sealing wedge.Since the respective bridge spans the connecting channel of the flow path and does not close or interrupt it, the connecting channel extends further below the bridge and the coolant can flow axially unhindered in the connecting channel of the flow path.

[0029] MAHLE internal restricted (CL2) December 16, 2025

[0030] 6

[0031] The flow path can have at least two collecting chambers, and the collecting chambers can be axially spaced apart from each other within the at least one sealing wedge. The webs formed on the surfaces of the at least one sealing wedge can be arranged in pairs opposite each other in the direction of rotation, and each collecting chamber can then be bounded externally in the direction of rotation by a pair of webs. The connecting channels of the flow path can then be guided fluidically through the at least two collecting chambers.

[0032] The rotor can have two annular collecting chambers. These chambers can be located on both sides of the winding carrier and adjacent to the windings axially. Furthermore, the rotor can have an inlet path formed in the shaft, comprising an axially oriented inlet channel and at least one radially oriented inlet opening. The inlet channel can lead fluidically from the outside to the at least one inlet opening, and the at least one inlet opening can lead from the inlet channel into one of the collecting chambers. The flow path formed in the at least one sealing wedge can then be fluidically connected to the inlet path via one of the collecting chambers. The coolant can then flow into the inlet channel from the outside, i.e., from outside the rotor, and be directed further into the at least one inlet opening. From the inlet opening, the coolant can flow into one of the collecting chambers and then be directed into the flow path formed in the sealing wedge.In the flow path of the sealing wedge, the coolant can flow axially along the sealing wedge and cool the windings adjacent to the sealing wedge. The coolant can then be collected in the other collection chamber and discharged from the rotor to the outside – for example, through at least one drain channel.

[0033] MAHLE internal restricted (CL2) December 16, 2025

[0034] 7

[0035] 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 directed approximately radially, 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 directed 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] They show, schematically, each one

[0040] MAHLE internal restricted (CL2) December 16, 2025

[0041] 8

[0042] Fig. 1 shows a partial sectional view of a rotor according to the invention with multiple windings and multiple locking wedges;

[0043] Fig. 2 shows a view of the locking wedge of the rotor according to the invention, which is composed of two wedge pieces;

[0044] Fig. 3 shows a view of one of the wedge pieces of the locking wedge of the rotor according to the invention;

[0045] Fig. 4 shows a sectional view of the rotor according to the invention along a cutting plane oriented perpendicular to the axis of rotation of the rotor.

[0046] Fig. 1 shows a partial sectional view of a rotor 1 according to the invention for an electric machine, in particular for a separately excited synchronous machine. The rotor 1 is shown here cut along two radially oriented cutting planes at an angle of less than 180° to each other. The rotor 1 comprises a shaft 2, a winding carrier 3, several windings 4, two balancing disks 5a and 5b, and several locking wedges 6. In total, the rotor 1 has six windings 4 and six locking wedges 6, of which only two are visible in Fig. 1.

[0047] 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 8a and 8b, with the base body 7 arranged axially between the end caps 8a and 8b. Several radially outwardly directed poles 9 – here a total of six – are formed on the winding carrier 3, distributed around the axis of rotation RA and in a direction of rotation UR around the axis of rotation RA.

[0048] MAHLE internal restricted (CL2) December 16, 2025

[0049] 9

[0050] The windings 4 are wound around the poles 9, each winding 4 consisting of several turns of an electrically conductive wire or copper wire. The individual windings 4 extend axially for the most part, except at the winding ends, and are spaced apart from each other in the direction of rotation UR. Several axially oriented grooves 10 – six in total – are formed between the windings 4 adjacent in the direction of rotation UR. The locking wedges 6 are arranged in the grooves 10 and close them. The balancing discs 5a and 5b enclose the winding carrier 3 on the base body 7 from the outside and hold it together.

[0051] The rotor 1 also has an inlet path 12 formed in the shaft 2, with an inlet channel 13 and several – here six – inlet openings 14. The inlet channel 13 is closed at one end in the shaft 2 and axially oriented. The inlet channel 13 leads from outside the rotor 1 to the inlet openings 14. The inlet openings 14 are radially oriented and distributed around the axis of rotation RA. Furthermore, the rotor 1 includes two collecting chambers 15a and 15b, which are formed on both sides of the winding carrier 3 between the winding carrier 3 and the balancing disks 5a and 5b. The collecting chamber 15a is fluidically connected to the inlet openings 14 of the inlet path 12. In each sealing wedge 6, a flow path 16 with axial connecting channels 18 is also formed. The construction of the sealing wedge 6 and the flow path 16 is explained in more detail below with reference to Fig. 2 and Fig. 3.The flow paths 16 are fluidically connected on one side to the collection chamber 15a and on the other side to the collection chamber 15b. Furthermore, the rotor 1 comprises several – here six – discharge channels 17. The discharge channels 17 are fluidically connected to the collection chamber 15b.

[0052] MAHLE internal restricted (CL2) December 16, 2025

[0053] 10

[0054] As indicated by arrows in Fig. 1, the coolant – for example, oil – flows into the rotor 1 through the inlet channel 13 of the inlet path 12. From the inlet channel 13, the coolant is directed into the inlet openings 14 of the inlet path 12 and flows further into the collection chamber 15a. From the collection chamber 15a, the coolant is directed into the individual flow paths 16 formed in the sealing wedges 6. From the flow paths 16, the coolant flows into the collection chamber 15b and out of the rotor 1 via the outlet channels 17.

[0055] Fig. 2 shows a view of the locking wedge 6 of the rotor 1 according to the invention. The locking wedge 6 is composed of two separate and identical wedge pieces 19a and 19b along a connecting plane VE. The wedge pieces 19a and 19b are formed using a primary forming process and are bonded together. In particular, the wedge pieces 19a and 19b can be formed from plastic – for example, thermoplastic – using an injection molding process and welded together. The connecting plane VE is oriented radially to the axis of rotation RA and passes through a longitudinal center axis LMA of the locking wedge 6. The longitudinal center axis LMA is aligned parallel to the axis of rotation RA.

[0056] In the respective sealing wedge 6, as explained above, the flow path 16 is formed with several connecting channels 18. The connecting channels 18 are aligned axially or parallel to the axis of rotation RA and extend over the entire axial length of the sealing wedge 6. The connecting channels 18 are formed as grooves on two opposing surfaces 20a and 20b of the sealing wedge 6. The surfaces 20a and 20b are aligned transversely to the circumferential direction UR and parallel to the axis of rotation RA and are arranged facing the respective windings 4 adjacent to the sealing wedge 6.

[0057] MAHLE internal restricted (CL2) December 16, 2025

[0058] 11

[0059] The sealing wedge 6 is divided into wedge sections 19a and 19b such that one surface 20a is assigned to one wedge section 19a and the other surface 20b to the other wedge section 19b. The connecting channels 18 are open on one side to the adjacent windings 4 of the sealing wedge 6, so that the windings 4 are directly exposed to the coolant flowing in the connecting channels 18. This allows the windings 4 to be effectively cooled regardless of the material of the sealing wedge 6.

[0060] To support the windings 4 on surfaces 20a and 20b, the locking wedge 6 comprises several—here ten—webs 21a and 21b. The webs 21a are located axially spaced from each other on surface 20a of the locking wedge 6, and the webs 21b are located axially spaced from each other on surface 20b of the locking wedge 6. The webs 21a on surface 20a and the webs 21b on surface 20b are positioned opposite each other in the direction of rotation UR. The webs 21a and 21b bridge the connecting channels 18, so that the connecting channels 18 are not interrupted axially. Within the locking wedge 6, several—here five—collecting chambers 22 are also formed, which are bounded on both sides in the direction of rotation UR by the respective opposing webs 21a and 21b. The respective connecting channels 18 pass behind the bridges 21a and 21b through the respective collecting chambers 22.The individual collecting chambers 22 are axially spaced apart from each other and are formed partly in the wedge piece 19a and partly in the wedge piece 19b.

[0061] Fig. 3 shows a view of the wedge piece 19a or 19b of the locking wedge 6 of the rotor 1 according to the invention. As already shown in Fig. 2, the wedge pieces 19a and 19b are materially bonded to the locking wedge 6 along the connection plane VE. In Fig. 3 it can be seen that the connecting channels 18

[0062] MAHLE internal restricted (CL2) December 16, 2025

[0063] The flow path 16 passes through the respective collecting chambers 22. The wedge piece 19a or 19b can be easily demolded in the direction indicated by arrows during the primary forming process. The multi-part design of the closure piece 6 allows for a simple implementation of the flow path 16 geometry adapted to the cooling of the windings 4.

[0064] Fig. 4 shows a sectional view of the rotor 1 according to the invention along a section plane oriented perpendicular to the axis of rotation RA of the rotor 1. In Fig. 4 it is particularly evident that the surfaces 20a and 20b of the locking wedge 6 bear against the adjacent windings 4, and thus the cooling fluid flowing in the connecting channels 18 can directly act upon or flow around the windings 4.

[0065] *****

[0066] MAHLE internal restricted (CL2)

Claims

December 16, 2025 13 Claims 1. Rotor (1 ) for an electric machine, in particular for a separately excited synchronous 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), - wherein at least one of the locking wedges (6) has at least two separate wedge pieces (19a, 19b) and the wedge pieces (19a, 19b) are connected to each other by material bonding and / or form bonding to form the locking wedge (6), and - wherein the at least one sealing wedge (6) has a flow path (16) through which a cooling fluid can flow and the flow path (16) of the sealing wedge (6) to the windings (4) adjacent to the sealing wedge (6) is at least partially open.

2. Rotor (1) according to claim 1, characterized in that LE internal restricted (CL2) December 16, 2025 14 - that the at least two wedge pieces (19a, 19b) of the at least one locking wedge (6) are formed in a primary forming process from plastic, preferably from a thermoplastic, and / or - that the at least two wedge pieces (19a, 19b) of the at least one locking wedge (6) are joined to the at least one locking wedge (6) by a material bond, in particular by welding or soldering or gluing.

3. Rotor (1 ) according to claim 1 or 2, characterized in that the at least one locking wedge (6) has exactly two wedge pieces (19a, 19b) which are materially connected to the at least one locking wedge (6) along a connection plane (VE) oriented radially to the axis of rotation (RA) and passing through the longitudinal center axis (LMA) of the at least one locking wedge (6).

4. Rotor (1) according to one of the preceding claims, characterized in that - that the at least one locking wedge (6) has at least one stiffening element, preferably made of metal, and - that the at least one stiffening element is arranged radially outside the wedge pieces (19a, 19b) of the at least one locking wedge (6) and is positively connected to the wedge pieces (19a, 19b) of the at least one locking wedge (6).

5. Rotor (1) according to one of the preceding claims, characterized in that the at least two wedge pieces (19a, 19b) of the at least one locking wedge (6) are positively locked, in particular by a plug connection LE internal restricted (CL2) December 16, 2025 15 or snap connection or rivet connection, are connected to each other and thereby secured against radial and / or axial displacement relative to each other.

6. Rotor (1) according to one of the preceding claims, characterized in that - that the at least one locking wedge (6) has two axially aligned surfaces (20a, 20b) facing the winding (4) adjacent to the at least one locking wedge (6), - that the flow path (16) of the at least one sealing wedge (6) has at least two axially aligned connecting channels (18), - that at least one of the connecting channels (18) of the flow path (16) is formed on each surface (20a, 20b) of the at least one sealing wedge (6), and - that each connecting channel (18) of the flow path (16) is open on one side to the winding (4) adjacent to the at least one sealing wedge (6) and is bounded to the outside by this winding (4) and is thereby closed.

7. Rotor (1 ) according to claim 6, characterized in that the connecting channel (18) of the flow path (16) is formed as at least one axially oriented groove on the surface (20a, 20b) of the at least one sealing wedge (6).

8. Rotor (1) according to claim 6 or 7, characterized in that, - that the at least one locking wedge (6) has at least two webs (21a, 21b) oriented transversely to the direction of rotation (UR), LE internal restricted (CL2) December 16, 2025 16 - that at least one of the webs (21a, 21b) is formed on each surface (20a, 20b) of the locking wedge (6), and - that the webs (21a, 21b) bridge the respective connecting channels (18) of the flow path (16) formed on the surface (20a, 20b) of the at least one sealing wedge (6).

9. Rotor (1) according to claim 8, characterized in that, - that the flow path (16) has at least two collecting chambers (22) and the collecting chambers (22) are axially spaced apart from each other in the at least one sealing wedge (6), - that the webs (21a, 21b) formed on the surfaces (20a, 20b) of the at least one locking wedge (6) are opposite each other in pairs in the direction of rotation (UR) and each collecting chamber (22) is bounded to the outside in the direction of rotation (UR) by a pair of the webs (21a, 21b), and - that the connecting channels (18) of the flow path (16) are guided fluidically through the at least two collecting chambers (22).

10. Rotor (1) according to one of the preceding claims, characterized in that - that the rotor (1 ) has two annular collecting spaces (15a, 15b) and the collecting spaces (15a, 15b) are formed adjacent to the winding carrier (3) on both sides and axially to the windings (4), - that the rotor (1 ) has an inlet path (12) formed in the shaft (2) with an axially oriented inlet channel (13) and at least one radially oriented inlet opening (14), LE internal restricted (CL2) December 16, 2025 17 - that the inlet channel (13) leads fluidically from the outside to the at least one inlet opening (14) and the at least one inlet opening (14) leads from the inlet channel (13) into one of the collection chambers (15a, 15b), and - that the flow path (16) formed in the at least one sealing wedge (6) is fluidically connected to the inlet path (12) via the one collecting chamber (15a, 15b). LE internal restricted (CL2)

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