Slot wedge for a rotor in an electric motor with improved electrical insulation and dimensional stability

Abstract

The invention relates to a slot wedge (142) for a rotor (116) in an electric machine (102), comprising a wedge body (148) and a cover element (150), wherein the wedge body (148) extends between a radially inner end (162) and a radially outer end (158) in such a way that a tapering portion (160) is formed which extends from the radially outer end (158) to the radially inner end (162); the cover element (150) is provided on the radially outer end (158) of the wedge body (148); and the wedge body (148) is made of a first material, and the cover element (150) is made of a second material which has a lower degree of rigidity than the first material. The invention also relates to a rotor (116), to an electric machine (102), and to an at least partly electrified vehicle (100).

Description

[0001] August 14, 2025

[0002] 1

[0003] Slotted locking wedge for a rotor in an electric motor with improved electrical insulation and dimensional stability

[0004] The present invention relates to a slotted locking wedge for a rotor in an electric motor. The present invention further relates to a rotor, an electric motor, and an at least partially electrified vehicle.

[0005] Fully electric vehicles and hybrid vehicles are well known from the prior art. These electric vehicles are driven exclusively or partially by one or more electric motors as drive units. The electric motor is generally equipped with a stator and a rotor rotatably mounted within the stator. The stator has several stator windings, known as phase strands, each of which is supplied with a corresponding phase current during operation. The phase currents are phase-shifted from one another, such that the current flowing through the stator windings produces a rotating magnetic field. The rotor has a rotor shaft and a rotor core assembly fixed to the rotor shaft, in which magnetically active components are mounted.The magnetic interaction between the rotor on the one hand and the stator-side rotating field on the other hand therefore generates a torque which sets the rotor in rotation.

[0006] In the case of an externally or electrically excited synchronous motor, the rotor core assembly typically comprises several rotor cores or poles distributed around the circumference of the rotor, each with a rotor coil wound around it to create a rotor winding. By applying a DC excitation current to the rotor coils, a DC magnetic field is generated at the rotor, which interacts with the rotating magnetic field on the stator side. The poles are axially elongated and, when assembled, each have a groove aligning with the adjacent poles. Slot-closing wedges are known in the prior art for closing these elongated grooves; these wedges are inserted into the rotor, particularly into the grooves. Such a slot-closing wedge is known, for example, from US 9,991,755 B2 or US 11,837,921 B1. 14.08.2025

[0007] 2

[0008] However, the slot-locking wedges known from the prior art have a number of disadvantages that impair the functionality of the electric drive. For example, the wedge known from US 9,991,755 B2 is a cast part, which has a limited degree of stiffness. This results in a rotor design with insufficient dimensional stability. A similar situation exists with the wedge or support element known from US 11,837,921 B1, which consists of a thermoplastic material such as polyamide or a mixture of polyamide and glass fibers and bears against a section of a rigid abutment element spanning the slot.

[0009] The object of the present invention is therefore to provide a slot locking wedge for the rotor with which the aforementioned disadvantages are at least partially overcome.

[0010] The aforementioned technical problem is solved by a slotted locking wedge, a rotor, an electric motor, and an at least partially electrified vehicle according to the main claim and the dependent claims. Advantageous embodiments are the subject of the dependent claims. The advantages described in connection with the claims relating to the slotted locking wedge also apply to the rotor, the electric motor, and the vehicle according to the invention.

[0011] In a first aspect of the present invention, a slot locking wedge for a rotor in an electric motor of an at least partially electrified vehicle is proposed. The electric motor comprises a stator and a rotor rotatably mounted in the stator about an axis of rotation. The stator typically has several phase strands designed as stator windings, into each of which an associated phase current is to be supplied. The phase currents are generated based on a DC input voltage by means of a DC / AC inverter, which converts the DC input voltage into an AC output voltage by switching several power switches connected as half-bridges. In this way, a rotating magnetic field is generated in the stator (stator magnetic field). The rotor comprises a 14.08.2025

[0012] 3

[0013] A rotor shaft, defining the axis of rotation, and a magnetically acting rotor core assembly, mounted at the rotational angle to the rotor shaft, which can be designed as an arrangement of several laminated sheet metal parts, preferably made of steel. The magnetic interaction between the stator and the rotor results in a torque, which is transmitted via a gearbox, such as a reduced / single-stage gearbox, to an axle of the vehicle.

[0014] The rotor core assembly comprises several poles distributed circumferentially, and in particular evenly, around each pole, a rotor coil is wound. Preferably, several windings can be assigned to each pole, forming a winding group (or a winding package). Several, for example two, pole shoes are formed at a radial end section of each pole, between which a pole gap or slot is created. Thus, a groove extending radially outwards from a groove base to the air gap is formed between adjacent poles.

[0015] The slot closure wedge serves to at least partially close the slot. For this purpose, the slot closure wedge comprises a wedge body and a cover element. The wedge body extends between a radially inner end and a radially outer end, such that a taper is formed running from the radially outer end to the radially inner end. The wedge body is thus wider at the radially outer end than at the radially inner end. The cover element is arranged or attached to the radially outer end of the wedge body. The cover element is specifically designed to further, and preferably sealingly, close the pole gap between the adjacent pole shoes, between which the slot closure wedge is to be positioned. This achieves an effective reduction in the air resistance of the rotating rotor, particularly at higher speeds.The groove locking wedge is thus designed in two parts, with both the wedge body and the cover element extending axially in the direction of the poles and therefore having an axially elongated shape. 14.08.2025.

[0016] 4

[0017] The wedge body is formed from a first material, while the cover element is formed from a second material that has a lower degree of stiffness than the first material. The wedge body occupies the majority of the elongated groove. Because the wedge body has a higher degree of stiffness than the cover element, greater dimensional stability is achieved for the assembly consisting of the poles, including the pole shoes, and the groove closure wedge. The first material is preferably a metal such as aluminum. The second material is preferably electrically insulating and, for example, comprises a plastic material. Thus, the wedge body can be electrically insulated particularly effectively and reliably from the pole, especially from the arrangement of laminated sheet metal parts, by the cover element. Alternatively or additionally, the first material can have a higher density than the second material.

[0018] According to one embodiment, the cover element is arranged both radially and circumferentially between the pole shoes on the one hand and the wedge body on the other. This measure serves to achieve reliable insulation, particularly electrical insulation, between the wedge body and the pole shoes. Furthermore, this allows for a particularly tight seal of the pole gap between the pole shoes, which increases the shape stability of the rotor.

[0019] According to a further embodiment, the wedge body has first teeth in cross-section on its outer surface, which bears against the cover element, and the cover element has second teeth in cross-section on its inner surface, which bears against the wedge body, wherein the first and second teeth interlock. This interlocking results in a particularly positive-locking connection between the wedge body and the cover element, which, in addition to improved sealing of the pole gap, further improves the shape stability of the rotor.

[0020] According to another embodiment, two outermost second teeth of the cover element in the circumferential direction close off the first teeth of the wedge body circumferentially. 14.08.2025

[0021] 5. This means that the outermost second teeth of the cover element in the circumferential direction are arranged in cross-section and circumferentially outside the first teeth at the radially outer end of the wedge body in order to effectively physically and electrically insulate the wedge body at the radially outer end from the pole shoes.

[0022] According to a further embodiment, a substantially axially extending coolant channel is formed in the slotted wedge for guiding a coolant. The coolant preferably comprises a cooling liquid, more preferably oil. The coolant channel is preferably formed in the wedge body, with the coolant channel preferably being positioned closer to the radially outer end than to the radially inner end of the wedge body. In this way, the coolant channel can be realized with a comparatively large cross-sectional area for the coolant flow, which has a positive effect on the cooling performance.

[0023] According to a further embodiment, the cover element is attached to the radially outer end of the wedge body before the slot closure wedge is installed in the rotor. This attachment is preferably achieved by forming a positive fit, a toothed joint, a dovetail, or by bonding at the interface between the wedge body and the cover element. This measure allows for a slot closure wedge to be prefabricated as a complete unit for installation in the rotor, thus simplifying its manufacture.

[0024] According to a further embodiment, the cover element is formed by spraying a potting compound onto the wedge body, particularly onto its radial outer surface. The potting compound can be a plastic material. The spraying can be carried out before the slot closure wedge is installed in the rotor, thus enabling the slot closure wedge to be implemented as a prefabricated unit. Alternatively, the spraying can be carried out after the wedge body has been installed in the rotor or the associated slot, resulting in improved adhesion of the cover element to the pole shoes. 14.08.2025

[0025] 6

[0026] According to a further embodiment, the cover element is designed to be positioned between the pole shoes in such a way that it is held against the wedge body under tensile force. Alternatively or additionally, the wedge body is designed to be supported against the pole shoes via the cover element. These measures enable a particularly secure connection between the cover element and the wedge body, ensuring that the groove closure wedge is stably held in the groove.

[0027] According to a further embodiment, in a state where the slot locking wedge is installed in the rotor, at least one winding group comprising a plurality of windings is arranged between the slot locking wedge and one of the poles. Preferably, a winding group is arranged between the slot locking wedge and each of the two poles between which the slot locking wedge is located. The respective winding group is surrounded by electrical insulation, which is preferably in the form of an insulating film, for example, paper. The wedge body is preferably not surrounded by the electrical insulation, or at most only with its radially inwardly directed sides, in particular the two tapered surfaces between the radially outer end and the radially inner end and / or the side surfaces as well as the radially inner end surface of the radially inner end.Alternatively or additionally, the combination of electrical insulation and the cover element completely separates the wedge body in cross-section from the poles between which the slot closure wedge is arranged, including the pole shoes.

[0028] According to a further embodiment, both winding groups, each arranged in a space between the slot locking wedge and one of the two poles between which the slot locking wedge is located, are at least substantially completely surrounded in cross-section by the same insulating film (or insulating films, if several insulating films are used for this purpose). The insulating film preferably extends along a first inner wall side of the first space in which the first winding group is received, and along a second inner wall side of the second space in which the second winding group is received.

[0029] 7

[0030] The winding group is enclosed. Preferably, the insulating film also extends along the bottom of the groove between the two gaps. In this way, both winding groups can be electrically insulated laterally to the groove closure wedge with a single insulating film, which increases the manufacturing simplicity of the rotor. The single insulating film can, for example, have a greater length in cross-section than the sum of the lateral circumferences of the inner walls of the gaps and the width of the groove bottom, such that a first longitudinal end can be connected to a second longitudinal end of the insulating film after it has been wound around the respective winding group, in order to achieve complete enclosure of both winding groups in cross-section.

[0031] According to a further embodiment, the (first) insulating film forms a gap in cross-section at the radially inner end of the wedge body, which is sealed by a further (second) insulating film. With a suitable choice of the length of the first insulating film, the gap is formed between the first and second longitudinal ends. This measure allows the electrical insulation of the winding groups to be provided initially with a comparatively short first insulating film, while the length of the second insulating film for closing the gap can be subsequently determined depending on the positions of the two longitudinal ends of the first insulating film. In this way, material waste due to incorrect length estimation of the insulating films can be reduced.

[0032] Furthermore, a rotor for an electric motor is proposed within the scope of this work, comprising a slotted locking wedge according to any of the embodiments described herein. The rotor can have an arrangement of laminated sheet metal parts (sheet metal stack) made of a ferromagnetic material, in particular an iron-based material such as steel.

[0033] Within the scope of the present application, an electric motor for an at least partially electrified vehicle is further proposed, comprising a rotor according to any of the embodiments disclosed herein and a stator. The electric motor can, in particular, be classified as an externally or electrically excited synchronous motor (EESM). 14.08.2025

[0034] 8. In particular, the electric motor may be an inductively excited synchronous motor (IEESM). The electric motor can function as the sole drive unit or alternatively as one of several drive units, for example in the case of a hybrid electric vehicle (HEV) with a combination of an electric drive unit and an internal combustion engine. The electric motor may have a substantially cylindrical outer contour or a conical outer contour, e.g., for a brake motor.

[0035] Within the scope of the present invention, an at least partially electrified vehicle comprising the electric motor according to the invention is proposed. The at least partially electrified vehicle can be, for example, a purely electric vehicle (EV), such as a battery electric vehicle (BEV), or a hybrid electric vehicle (HEV).

[0036] The aspects mentioned above serve illustrative purposes and are not intended to limit the scope of the invention. Numerous variations of the aspects described above are possible. The various aspects discussed in this disclosure can be combined in any way to produce additional advantages. Furthermore, some of the features can form the basis for one or more divisional applications.

[0037] The invention is explained below with reference to examples using the embodiments shown in the figures. The figures show:

[0038] Fig. 1 shows a schematic representation of a vehicle comprising an electric axle drive with an electric motor;

[0039] Fig. 2 shows a schematic representation of a rotor of the electric motor in a cross-sectional view;

[0040] Fig. 3 shows a schematic representation of a slot locking wedge for installation in the rotor, in particular in an elongated slot between adjacent poles of the rotor, in a perspective view; 14.08.2025

[0041] 9

[0042] Fig. 4 shows a schematic representation of the groove locking wedge in a cross-sectional view;

[0043] Fig. 5A is a schematic representation of a wedge body of the

[0044] Groove locking wedge in a cross-sectional view;

[0045] Fig. 5B a schematic representation of a cover element of the

[0046] Groove locking wedge in a cross-sectional view;

[0047] Fig. 6 shows a schematic representation of the slot closure wedge in a cross-sectional view, wherein the slot closure is installed between the adjacent poles of the rotor and is received in the elongated slot.

[0048] The same objects, functional units, and comparable components are identified by the same reference numbers in the figures. These objects, functional units, and comparable components are identical with respect to their technical characteristics unless the description explicitly or implicitly discloses otherwise.

[0049] Fig. 1 shows a schematic representation of a vehicle 100 that is at least partially electrified. The vehicle 100 can be a purely electric vehicle or a hybrid vehicle. The vehicle 100 is equipped with an electric axle drive comprising an electric motor 102, a DC / AC inverter 106, and a gearbox 112. The electric motor 102 is designed here as an externally excited synchronous motor (EESM). The electric motor 102 comprises a stator (not shown in detail) with several phase strands arranged as stator windings and a rotor 116 (see Fig. 2) comprising one or more electrically conductive rotor coils. The inverter 106 is connected between the drive battery 106 and the electric motor 102 to convert a DC input voltage provided by a traction battery 104 into an AC output voltage.In particular, several circuit breakers installed in the inverter 106 are preferably switched on at 14.08.2025.

[0050] Ten sinusoidally shaped, phase-shifted phase currents are generated for the phase strands of the stator. Each phase current, fed into one of the stator's phase strands, creates a rotating magnetic field within the stator. The rotor 116, or rotor coil, is supplied with a DC excitation current, resulting in a stationary magnetic field on the rotor 116. Based on the interaction between the rotating stator magnetic field and the stationary rotor magnetic field, a torque is generated. This torque is transmitted via the gearbox 112, which preferably has a reduced gear ratio, to an axle 110 (here, for example, the rear axle of the vehicle 100) and finally to wheels 114 (here, for example, rear wheels).

[0051] Fig. 2 shows a schematic cross-sectional view of the rotor 116. The rotor 116 has a rotor shaft 120, which defines an axis of rotation 118 of the rotor 116. Additionally, the rotor 116 has several poles 124 arranged circumferentially. The poles 124 each extend radially outwards from an inner ring 122, which is fixedly attached to the rotor shaft 120. A pole shoe 126 is formed integrally with the pole 124 on the outside of each pole 124. The pole shoes 126 each have an arc shape that is symmetrical with respect to the corresponding pole 124 (or about a radial center line of the pole 124). Between adjacent poles 124 a groove 128 is formed, which extends radially outwards from a groove base 132 to a pole gap 130 between the associated pole shoes 126.The groove 128 is defined laterally by side surfaces 134, 136 of the poles 124, between which the groove 128 is located, and by inner surfaces 138, 140 of the associated pole shoes 126. The poles 124, including the pole shoes 126, and the inner ring 122 form a rotor core assembly of the rotor 116, which surrounds the rotor shaft 120 in a rotationally fixed manner.

[0052] Fig. 3 shows a schematic perspective view of a slot closure wedge 142 for installation in the rotor 116, in particular in the elongated slot 128 between the adjacent poles 124 of the rotor 116. The slot closure wedge 142 serves to close the slot, at least partially, in order to reduce the air resistance of the rotor.

[0053] To reduce the resistance of the rotating rotors 116 and thereby achieve higher mechanical stability, the slot closure wedge 142, corresponding to the elongated slot 128, also has an elongated shape with a wedge-shaped cross-section. The slot closure wedge 142 is formed in two parts and comprises a wedge body 148 and a cover element 150. The wedge body 148 is formed from a first material, while the cover element 150 is formed from a second material that has a lower degree of stiffness than the first material. The first material is preferably a metal, such as aluminum. The second material is preferably a plastic material, such as polymer. As shown in Fig.As shown in Figure 3 by way of example, the cover element 150 extends beyond the wedge body 148 at two opposite longitudinal ends, such that the wedge body 148 is arranged longitudinally between a first end section 152 and a second end section 154 of the cover element 150. A coolant connection 144, 146 is formed at each end section 150, 152, which are connected to each other by a coolant channel 156 (not shown in detail in Figure 3, see, for example, Figure 4). The coolant channel 156 is designed to guide a preferably liquid coolant such as oil for the purpose of cooling the rotor 116.

[0054] Fig. 4 shows a schematic cross-sectional view of the groove closure wedge 142. The two components of the groove closure wedge 142, namely the wedge body 148 and the cover element 150, are shown schematically in Fig. 5A and Fig. 5B, respectively. It can be seen that the coolant channel 156 is located in an upper region of the wedge body 148. The wedge body 148 comprises three sections that follow one another along the radial direction: a radially outer end 158, a tapered section 160, and a radially inner end 162. Several first teeth 164 are formed at the radially outer end 158, in particular on an outer surface 166, of the wedge body 148. On an inner side 175 of the cover element 150, second teeth 174, 176 are formed, extending from a main section 173 of the cover element 150.The first teeth 164 and the second teeth 174, 176 are designed to fit together in such a way that, when assembled, the first teeth 164 and the second teeth 174, 176 interlock. 14.08.2025.

[0055] 12

[0056] In this way, a positive-locking connection or interlocking is achieved between the wedge body 148 and the cover element 150. As can be seen in Fig. 3, the first teeth 164 of the wedge body 148 are arranged between and thus enclosed by two outermost second teeth 176 of the cover element 150 in the circumferential direction. This increases the dimensional stability of the groove closure part 142 in the assembled state. Furthermore, the outermost second teeth 176 of the cover element 150 are shaped such that they each allow a flush transition to a tapered surface 168 of the wedge body 148. However, this is not a limitation for the present invention. It is also conceivable that the second teeth 174, 176 of the cover element 150 are arranged between two first teeth 164 of the wedge body 148 that are outermost on the circumference, the latter having a flush transition to the tapered surfaces 168 of the wedge body 148.The tapered section 160 extends between the radially outer end 158 and the radially inner end 162, wherein the tapered section 160 is wider on the radial outer side than on the radial inner side. At the radially inner end 162, the wedge body 148 has a nose shape with two opposing side surfaces 170 and an end face 172.

[0057] Fig. 6 shows the slot closure wedge 142 in a state in which the slot closure wedge 142 is inserted into the rotor 116, in particular into the elongated slot 128 between two adjacent poles 124a, 124b. It can be seen that, in the inserted state of the slot closure wedge 142, the cover element 150 essentially closes the pole gap 130 (see Fig. 2) between the pole shoes 126a, 126b of the poles 124a, 124b, by forming a positive fit with the pole shoes 126a, 126b both radially and circumferentially. In particular, the cover element 150 is arranged both radially and circumferentially between the respective pole shoe 126a, 126b on the one hand and the wedge body 148 on the other.This provides not only physical but also electrical insulation between the pole shoes 126a, 126b on the one hand and the wedge body 148 on the other, provided the cover element 150 is made of an electrically insulating material such as plastic or polymer. 14.08.2025.

[0058] 13

[0059] As shown purely by way of example in Fig. 6, the pole shoes 126a, 126b each have a stepped inner surface 138, 140. The step shape is chosen such that it positively engages the outermost second teeth 176 of the cover element 150 from the outside. Each of the poles 124a, 124b is assigned a (first or second) winding group 180a, 180b comprising a plurality of rotor windings 178a, 178b, wherein the winding groups 180a, 180b are each accommodated in a space between the associated pole 124a and the slot locking wedge 142. The winding groups 180a, 180b are in cross-sectional view essentially completely surrounded by an insulating film 182, i.e. by the same insulating film 182 which provides electrical insulation.The insulating foil 182 comprises a first foil section 182a, which substantially encloses the first winding group 180a, and a second foil section 182b, which substantially encloses the second winding group 180b. The first foil section 182a extends from a first longitudinal end 184a along an inner wall side of the first space accommodating the first winding group 180a, namely along a first side surface 170 and a first tapered surface 168 of the wedge body 148, the inner surface 138 of the first pole shoe 126a, the side surface 134 of the first pole 124a to the groove bottom 132 of the elongated groove 128.Similarly, the second foil section 182b extends from a second longitudinal end 184b along an inner wall side of the second space accommodating the second winding group 180b, namely along a first side surface 170 and a first tapered surface 168 of the wedge body 148, the inner surface 140 of the second pole shoe 126b, the side surface 136 of the second pole 124b to the groove base 132 of the elongated groove 128. At the groove base 132, the first foil section 182a and the second foil section 182b merge into one another. The insulating foil 182 is in a form-fitting manner against the respective sections of the inner wall side of both spaces and against the surface of the groove base 132. In this way, the rotor windings 178a, 178b of the winding groups 180a, 180b are particularly securely positioned in the spaces between and thus in the rotor 116. As shown in Fig.As can be further seen in Figure 6, the two longitudinal ends 184a, 184b of the insulating film 182 form a gap in the region of the radially inner end 162 of the wedge body 148, which is closed by another insulating film 186. Thus, the longitudinal ends 184a, 184b are closed by the 14.08.2025.

[0060] Fourteen further insulating films 186 are connected to one another and are positively attached to the side surfaces 170 and the end face 172 of the wedge body 148. On the side surfaces 170 of the radially inner end 162 of the wedge body 148, both insulating films 182, 186 are arranged overlapping each other, which ensures reliable electrical insulation between the wedge body 148 and the rotor windings 178a, 178b, as well as a reliable connection between the two insulating films 182, 186. The use of the same insulating film 182 for the essentially complete insulation of the rotor windings 178a, 178b from the wedge body 148 simplifies the manufacture of the rotor 116, since only the single insulating film 182 needs to be guided along the gaps. The use of the additional insulating film 186 is not limiting for the present invention.It is also conceivable to select the (first) insulating foil 182 with respect to length such that the longitudinal ends 184a, 184b of the insulating foil 182 can be joined overlapping each other and thus the insulating foil 182 is able to provide full insulation of the winding groups 180a, 180b independently.

[0061] The cover element 150 can be attached to the radially outer end 158 of the wedge body 148 before the slot closure wedge 142 is installed in the rotor 116 or in the elongated slot 128. Alternatively, the cover element 150, for example as an injection-molded potting compound, can be applied to the outer surface 166 of the wedge body 148 before the slot closure wedge 142 is installed. Furthermore, the cover element 150 is preferably designed to be arranged between the pole shoes 126, 126a, 126b in such a way that the cover element 150 is held against the wedge body 148 under tensile force. The wedge body 148 is further preferably designed to be supported against the pole shoes 126, 126a, 126b via the cover element 150. These measures lead to improved positional and dimensional stability of the slot locking wedge 142 in the rotor 116, which has a positive effect on the functionalities of the electric motor 102. 8.2025

[0062] 15

[0063] Reference numeral list: at least partially electrified vehicle, electric motor (externally excited synchronous motor), traction battery, DC / AC inverter, control unit, rear axle, gearbox, rear wheels, rotor, axis of rotation, rotor shaft, inner ring, pole, a first pole, b second pole, pole shoe, a first pole shoe, b second pole shoe, elongated groove, pole gap, groove base, 136, side surfaces, 140, inner surfaces, groove locking wedge, 146, coolant connections, wedge body, cover element, 154, end sections, coolant channel, radial outer end, 8.2025, tapered section, radial inner end, first teeth, outer surface, tapered surfaces, side surfaces, end face, main section, second teeth, inner surface, outermost second teeth, a first rotor windings, b second rotor windings, a first winding group, b second winding group, first insulating film, a first film section, b second film section, a first longitudinal end, b second longitudinal end, second insulating film

Claims

August 14, 2025 17 Patent claims 1. Slot locking wedge (142) for a rotor (116) of an electric machine (102), comprising a wedge body (148) and a cover element (150), wherein the wedge body (148) extends between a radially inner end (162) and a radially outer end (158) such that a tapered section (160) extending from the radially outer end (158) to the radially inner end (162) is formed, wherein the cover element (150) is arranged at the radially outer end (158) of the wedge body (148), wherein the wedge body (148) is formed from a first material, and wherein the cover element (150) is formed from a second material having a lower degree of stiffness than the first material.

2. Slot locking wedge (142) according to claim 1, wherein the first material comprises a metal, preferably aluminium; wherein the second material is electrically insulating, preferably a plastic material, wherein the wedge body (148) is electrically insulated by the cover element (150) against pole shoes (126, 126a, 126b), in particular against a laminated lamination stack of the rotor (116), wherein the cover element (150) is configured to close a pole gap (130) between two pole shoes (126, 126a, 126b) of the rotor (116), preferably sealing.

3. Groove locking wedge (142) according to claim 2, wherein the cover element (150) is arranged both along a radial direction and along a circumferential direction between the pole shoes (126, 126a, 126b) on the one hand and the wedge body (148) on the other.

4. Groove locking wedge (142) according to one of the preceding claims, wherein the wedge body (148) has first teeth (164) in cross-section on an outer surface (166) acting upon the cover element (150), wherein the cover element (150) has second teeth (174, 176) in cross-section on an inner surface (175) acting upon the wedge body (148), wherein the first teeth (164) and the second teeth (174, 176) interlock. August 14, 2025 18 5. Groove locking wedge (142) according to claim 4, wherein two outermost second teeth (176) of the cover element (150) circumferentially enclose the first teeth (164) of the wedge body (148).

6. Groove locking wedge (142) according to one of the preceding claims, wherein a substantially axially extending coolant channel (156) is formed for guiding a coolant in the groove locking wedge (142), wherein the coolant preferably comprises a cooling liquid, more preferably oil, wherein the coolant channel (156) is preferably formed in the wedge body (148).

7. Groove locking wedge (142) according to one of the preceding claims, wherein the cover element (150) is attached to the radially outer end (158) of the wedge body (148) before the groove locking wedge (142) is installed in the rotor (116).

8. Groove locking wedge (142) according to one of the preceding claims, wherein the cover element (150) is formed by spraying a potting compound onto the wedge body (148).

9. Groove locking wedge (142) according to one of the preceding claims, wherein the cover element (150) is configured to be arranged between the pole shoes (126, 126a, 126b) in such a way that the cover element (150) is held against the wedge body (148) under a tensile force, and / or wherein the wedge body (148) is configured to be supported on the pole shoes (126, 126a, 126b) via the cover element (150).

10. Slot locking wedge (142) according to one of the preceding claims, wherein, in a state of the slot locking wedge (142) installed in the rotor (116), a winding group (180a, 180b) comprising a plurality of windings (178a, 178b) is arranged between the slot locking wedge (142) and one of several poles (124, 124a, 124b) of the rotor (116), wherein preferably a winding group (180a, 180b) is arranged between the slot locking wedge (142) and the two poles (124, 124a, 124b) between which the slot locking wedge (142) is arranged, wherein August 14, 2025 19 the winding group (180a, 180b) is surrounded by an electrical insulation (182, 186), which is in particular an insulating film, for example as paper.

11. Slot locking wedge (142) according to claim 10, wherein both winding groups (180a, 180b), each of which is arranged in an intermediate space between the slot locking wedge (142) and one of the two poles (124, 124a, 124b) between which the slot locking wedge (142) is arranged, are at least substantially completely surrounded in cross-section by the same insulating film (182).

12. Groove locking wedge (142) according to claim 11, wherein the insulating film (182) forms a gap in cross-section at the radially inner end (162) of the wedge body (148), which is sealed by a further insulating film (186).

13. Rotor (116) for an electric machine (102), in particular an externally excited synchronous motor, comprising a slot locking wedge (142) according to any one of claims 1 to 12.

14. Electric machine (102), in particular an externally excited synchronous motor, for an at least partially electrified vehicle (100), comprising a slot locking wedge (142) according to one of claims 1 to 12 or the rotor (116) according to claim 13.

15. At least partially electrified vehicle (100) comprising an electric machine (102), in particular an externally excited synchronous motor, according to claim 14.

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