Method for sealing and / or calibrating a rotor for an electric motor

Abstract

The present invention relates to a method for sealing and / or caulking a rotor (116) for an electric motor (102), which is in particular designed as an externally excited synchronous motor, the method comprising providing a rotor (116) having a rotor core arrangement that can be fixed to a rotor shaft (119) in a rotationally fixed manner, wherein the rotor core arrangement has several rotor teeth (124) distributed in a circumferential direction, wherein an axial longitudinal groove (128) is formed between adjacent rotor teeth (124), and wherein a rotor winding group (138, 140) is arranged around each of the rotor teeth (124);Forming a closure element (146) for closing an intermediate gap (130) between two opposing pole shoes (126) of two adjacent rotor teeth (124), such that the closure element (146) extends in an axial direction connecting the pole shoes (126) to define an elongated cavity (150) for receiving a groove closure part (170); wherein the closure element (146) is formed from a polymer by means of a forming process using at least one tool element (201, 202, 206, 207) that forms at least a portion of the shape. The present invention further relates to a rotor (116), an electric motor (102), and an at least partially electrified vehicle (100).

Description

[0001] The present invention relates to a method for sealing and / or caulking a rotor for an electric motor. The present invention further relates to a rotor, an electric motor, and an at least partially electrified vehicle.

[0002] 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, which serve as phase strands and are each 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 creates 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 installed.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.

[0003] In the case of an externally or electrically excited synchronous motor, the rotor core assembly typically comprises several rotor teeth distributed around the circumference of the rotor, defining the rotor poles. A conductor or copper wire is wound around each of these teeth to form a rotor coil (or rotor winding). By applying an excitation current to the rotor coils, a magnetic field is generated at the rotor, which interacts with the rotating magnetic field on the stator side. The rotor core assembly can be implemented, in particular, as an axial lamination of sheet metal parts or as one or more stacks of laminated cores. A longitudinal groove is formed between adjacent rotor teeth.

[0004] During operation, the current flowing through the rotor coils generates heat in the rotor. Inadequate cooling can lead to overheating of the rotor and consequently impair the functionality of the entire electric motor. Therefore, effective cooling of the rotor with a coolant is essential. Various cooling concepts for rotors are known in the art. In the so-called "wet runner principle," the entire electric motor is circulated with a liquid coolant, such as oil. This enables direct thermal coupling between the components installed in the electric motor and the coolant, allowing heat to be effectively dissipated from the rotor coils. However, coolant or oil present in the air gap between the stator and the rotor can cause drag losses, which negatively impact torque generation, particularly at higher speeds.

[0005] In the so-called "dry-runner principle," the liquid coolant or oil does not flow through the air gap, thus avoiding drag losses. A known method for achieving this is the so-called "flooded rotor design," in which the coolant is conveyed through the rotor, particularly the laminated core. The circulating coolant thus reaches the vicinity of the rotor windings and ensures effective and uniform heat dissipation.

[0006] It is essential to adequately seal the rotor against the coolant to prevent the coolant from entering the air gap. However, in rotors known from the prior art, this seal is not sufficient, so there is a risk that the liquid coolant or oil can easily enter the air gap and cause drag losses.

[0007] The object of the present invention is therefore to provide a method for sealing and / or caulking the rotor, which at least partially overcomes the aforementioned disadvantages.

[0008] The aforementioned technical problem is solved by a method for sealing and / or caulking a rotor, 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 directed to the method also apply to the rotor, the electric motor, and the vehicle according to the invention.

[0009] In a first aspect of the present invention, a method for sealing and / or caulking 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 configured as stator windings, into each of which a corresponding phase current is 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 is rotatably mounted about an axis of rotation of the electric motor and is magnetically active.The magnetic interaction between the stator and the rotor results in a torque which is transmitted to an axle of the vehicle via a gearbox, such as a reduced / single-stage gearbox.

[0010] The method for sealing and / or calibrating the rotor comprises a first process step in which the rotor is provided. The rotor comprises a magnetically actuated rotor core assembly that can be fixed to a rotor shaft in a rotationally fixed manner and that may be designed as an arrangement of at least one, but preferably several, laminated sheet metal parts or stacks, preferably made of steel. The rotor core assembly comprises several rotor teeth distributed circumferentially, in particular uniformly, around which a rotor winding group (or a rotor winding stack) with several rotor windings is arranged. Two pole shoes are formed on a radial end section of each rotor core, with an intermediate gap arranged between two opposing pole shoes of two adjacent rotor teeth.Thus, a longitudinal groove is formed between adjacent rotor teeth, extending radially outwards from a groove base to the gap between the pole shoes.

[0011] The method for sealing and / or caulking the rotor comprises a further process step in which a sealing element is provided to close the gap between the pole shoes of adjacent rotor teeth. The sealing element is elongated and arranged such that it extends axially between the adjacent rotor teeth. This means that the sealing element extends axially to the length of the rotor teeth and connects the pole shoes of the adjacent rotor teeth circumferentially. This creates an elongated cavity that extends circumferentially between the rotor winding groups attached to the adjacent rotor teeth and radially from the bottom of the longitudinal groove to a radial inner surface of the sealing element. The elongated cavity serves to accommodate a groove sealing component, in particular a groove sealing wedge.

[0012] According to the invention, the closure element is formed from a polymer by means of a forming process using at least one tool element that shapes at least parts of the form. The forming process is designed to produce molded parts from the polymer with a geometric shape defined by the at least one tool element. The at least one tool element is preferably brought close to the pole shoes and the rotor windings, so that a space is formed between the pole shoes that is completely enclosed except for an entry point (or sprue or gate) for introducing the polymer. During the forming process, the polymer is then introduced into the space via the entry point formed in the at least one tool element.

[0013] The shaping tool element can be designed as an end-face tool half and / or as an outer tool core and / or as an inner tool core.

[0014] The polymer used for the closure element is preferably a polymeric molding compound, in particular a thermosetting or thermoplastic polymer, or alternatively a thermoplastic elastomer. These material classes are particularly suitable for molding the closure element due to their easy availability and their electrically insulating, thermally conductive, and mechanically stable properties. These material classes can also be used for a variety of molding processes.

[0015] The method described above, and which will be further specified below, initially relates to a single closure element associated with a longitudinal groove, a rotor core pair, or a pole shoe pair, and which defines an elongated cavity. It is understood that the method according to the invention can be extended to a plurality of closure elements, each associated with a corresponding longitudinal groove, a corresponding rotor core pair, or a pole shoe pair, and each defining an elongated cavity. Preferably, the same process steps are carried out simultaneously for the plurality of closure elements or longitudinal grooves, rotor core / pole shoe pairs, and elongated cavities, so that the sealing and / or cavities can be performed with high process efficiency.

[0016] The method can additionally include the prior provision of the rotor shaft. This is preferably done before the insertion of the locking element, in particular by securing the rotor shaft in the rotor core assembly in a rotationally fixed manner. Alternatively, the rotor shaft can be provided after the insertion of the locking element.

[0017] The method according to the invention makes it possible to form elongated cavities for the secure reception of a slot closure part, in particular a slot closure wedge. The elongated cavities can also serve as coolant channels for guiding a coolant, such as oil. According to the invention, the forming process enables a reliable closure of the respective gaps between the pole shoes of adjacent rotor teeth, thereby achieving improved sealing of the rotor.

[0018] According to an exemplary embodiment, an outer tool core is used to define a radial outer contour of the locking element. Alternatively or additionally, an inner tool core is used to define a radial inner contour of the locking element. In particular, the outer and inner tool cores are positioned simultaneously near the pole shoes of the adjacent rotor teeth, so that the gap between them is limited in the radial direction. This allows for a simple definition of the cross-section of the locking element.

[0019] According to a further exemplary embodiment, an end-face tool arrangement is used, comprising a first end-face tool half and a second end-face tool half. During the forming process, the end-face tool halves are each brought into contact with an end face of the rotor core assembly, in particular a laminated stack of laminations, to axially seal the rotor against the introduced polymer. The first end-face tool half, in which the sprue channel for introducing the polymer is formed, is fixedly positioned on a first end face of the rotor core assembly during the forming process. The second end-face tool half is movably positioned on a second end face of the rotor core assembly opposite the first end face during the forming process. In this way, the sealing element to be formed is also defined with respect to the longitudinal direction.

[0020] According to a further exemplary embodiment, at least one of the end-face tool halves can form a single-piece assembly or a unit composed of the tool half and the tool core in question with one of the tool cores, preferably with the inner tool core.

[0021] According to another exemplary embodiment, the forming process is suitable for optimally matching the axial length of the closure elements to the specific axial length of the rotor core assembly. This enables, for example, the simple and reliable installation of a sealing ring for axial sealing of the rotor and thus increases the axial tightness of the rotor. The forming processes provided for the individual closure elements can each be carried out with a correspondingly adapted set of process parameters, such as process duration, amount of polymer used, and opening size of the inlet point or connection channel.

[0022] According to another exemplary embodiment, the forming process is designed such that the closure element comprises two axial end sections and an intermediate section arranged between them. For this purpose, the forming process includes, for example, a first sub-process with a first set of process parameters for forming the intermediate section and a second sub-process with a second set of process parameters for forming both axial end sections. Preferably, the first sub-process is carried out before the second sub-process. Both sets of process parameters differ at least in the tool cores used. It is also conceivable to apply a separate sub-process with an associated set of process parameters for each of the three sections. This measure enables a multi-component closure element with different mechanical and / or thermal properties between the different sections.The locking element shaped in this way can therefore be adapted to the different application requirements at various points on the rotor.

[0023] According to another exemplary embodiment, the intermediate section is formed from a first polymer, while the axial end sections are formed from a second polymer different from the first. Suitable first polymers include, for example, thermosets or thermosets. Suitable second polymers include, for example, thermoplastic elastomers. It is also conceivable to form the three sections of the closure element from three different polymers. The closure element formed in this way is therefore more adaptable to the different application requirements at various locations on the rotor.

[0024] According to another exemplary embodiment, the forming process comprises a casting process, in particular an injection molding process, and / or a pressing process, in particular an injection compression molding process. The casting process enables the production of complex and precise shapes with a high degree of detail. It also offers high flexibility in material selection, with resins or epoxies being suitable polymers. The injection molding process is particularly advantageous due to its speed (which corresponds to a shorter processing time), precision, flexibility regarding material selection and shape formation, and high repeatability, which is important for the mass production of rotor components in particular. The pressing process is advantageous due to its high precision and repeatability. It also enables particularly high material utilization. It is especially suitable for sealing or...Sealing the rotor is achieved through the injection molding process, which enables high reproducibility and efficiency.

[0025] According to another exemplary embodiment, the closure element forms a lateral positive fit with the pole shoes of the adjacent rotor teeth in terms of its cross-section. This is preferably achieved by recessing an edge region of one pole shoe, and more preferably of both pole shoes of the adjacent rotor teeth. The recess can be formed by punching, laser cutting, and / or etching. During the forming process, the polymer is introduced into the recessed edge region of the respective pole shoe to shape the corresponding lateral edge(s) of the closure element. After cooling or curing of the introduced polymer, a positive-locking connection or interlock is formed between the closure element and the respective pole shoe, which further improves the sealing of the rotor in the radial direction.

[0026] According to another exemplary embodiment, the method further comprises impregnating the rotor winding groups with an impregnating material. The impregnation of the rotor windings preferably takes place after the formation of the sealing element. This creates an elongated cavity extending circumferentially between two opposing impregnation surfaces, within which the rotor winding groups attached to the adjacent rotor teeth are enclosed, and radially between the sealing element and the bottom of the longitudinal groove. A thermosetting material such as resin or a potting compound can be used for the impregnation. A trickle impregnation process or one of the forming processes described above can be used to create the impregnation.In the latter case, the forming process and / or the polymer used for impregnation can differ from the forming process / polymer for the closure element. Alternatively, both separate process steps can use the same forming process or the same polymer. In this way, the rotor windings are mechanically and stably connected to each other, forming a solid winding unit. This improves heat transfer from the rotor windings to the surroundings, particularly to the rotor's laminated core and the components located between adjacent rotor teeth or pole shoes. The impregnation of the rotor winding groups resulting from the forming process also provides electrical insulation.

[0027] According to a further exemplary embodiment, the method further comprises removing the tool core(s) after forming the closure element and inserting the groove closure part, in particular the groove closure wedge, into the elongated cavity.

[0028] Another alternative for providing the groove closure part or wedge is the use of a molding process with a different polymer. For example, a separate molding process can be used for both the closure element and the impregnation, employing either the same polymer as the closure element or a different polymer. This approach allows for a particularly stable arrangement of the groove closure part or wedge, with improved sealing of the rotor.

[0029] According to a further exemplary embodiment, the method also includes attaching a sealing element to the end face of the rotor core assembly after the groove closure part has been inserted into the elongated cavity. The sealing element is attached to the end face of the rotor core assembly as a prefabricated component or produced by dispensing a curable sealant, preferably on both opposing end faces of the rotor core assembly. This measure provides additional axial sealing of the rotor.

[0030] Within the scope of the present invention, a rotor for an electric motor is also proposed, which is sealed and / or sealed by a method according to one of the embodiments of the invention. The rotor thus has at least one structural feature described in connection with the above and following methods. The rotor can comprise an arrangement of laminated sheet metal parts (laminated stacks) made of steel.

[0031] Within the scope of the present invention, 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 configured as an externally or electrically excited synchronous motor (EESM), especially an inductively electrically 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 can have a substantially cylindrical outer contour or a conical outer contour, e.g., for a brake motor.

[0032] 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).

[0033] 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.

[0034] The invention is explained below with reference to examples using the embodiments shown in the figures. The figures show: Fig. 1 a schematic representation of a vehicle comprising an electric axle drive with an electric motor; Fig. 2 a schematic representation of a rotor core arrangement of the electric motor in a cross-sectional view; Fig. 3 a schematic representation of a laminated sheet metal stack of the rotor core assembly in a side view before the formation of a locking element; Fig. 4 a schematic representation of the laminated sheet metal package in a top view, wherein two end-face tool halves of an end-face tool arrangement for forming the closure element are positioned on the end faces of the sheet metal package; Fig. 5 a schematic representation of the laminated sheet metal package in a side view, wherein, in addition to the end-face tool arrangement, an outer tool core and an inner tool core are positioned in the area of ​​an intermediate gap between two pole shoes of two adjacent rotor teeth; Fig. 6 A schematic representation of the laminated sheet metal package in a side view after forming of the closure element, showing an elongated cavity; Fig. 7 a schematic representation of the locking element according to one embodiment in a side view; Fig. 8 a schematic representation of the locking element according to a further embodiment in a side view; Fig. 8 a schematic representation of the locking element according to a further embodiment in a side view; Fig. 9 a schematic representation of the locking element according to a further embodiment in a side view; Fig. 10 a schematic representation of the locking element according to a further embodiment in a side view; Fig. 11 a schematic representation of the closure element in a top view, comprising two axial end sections and an intermediate section arranged between them; Fig. 12 a schematic representation of the rotor in a perspective view, wherein a plurality of tool cores are included in the elongated cavities for the purpose of impregnating rotor windings by means of a forming process; Fig. 13 a schematic representation of the rotor core arrangement in a cross-sectional view after impregnation of the rotor windings, showing an elongated cavity; Fig. 14 a schematic representation of the laminated sheet metal stack, wherein a slot closure wedge is received in the elongated cavity, wherein a sealing ring is attached to the end face of the rotor core assembly; Fig. 15 a schematic representation of the rotor in a perspective view, wherein two end-face balancing discs are axially connected to the rotor core assembly for axial sealing of the rotor.

[0035] The same objects, functional units, and comparable components are identified in the figures by the same reference numbers. These objects, functional units, and comparable components are identical with respect to their technical characteristics unless the description explicitly or implicitly reveals otherwise.

[0036] Fig. Figure 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 here) with several phase strands arranged as stator windings and a rotor 116 (see Figure 1). Fig. 2) comprising several electrically conductive rotor windings. The inverter 106 is connected between the drive battery 106 and the electric motor 102 for the purpose of converting a DC input voltage provided by a drive battery 104 into an AC output voltage. In particular, several preferably sinusoidal, phase-shifted phase currents for the stator phase strands are generated by opening and closing several power switches installed in the inverter 106. The phase currents, each fed into one of the several phase strands of the stator, cause a rotating magnetic field in the interior of the stator. The rotor 116, or the rotor windings, are subjected to an excitation current, resulting in a magnetic field on the rotor 116. A torque is generated based on the interaction between the rotating stator magnetic field and the stationary rotor magnetic field., which is transmitted by means of the transmission 112, which preferably has a reduced transmission, to an axle 110, here by way of example the rear axle of the vehicle 100, and finally to wheels 114, here by way of example rear wheels.

[0037] Fig. Figure 2 shows a schematic cross-sectional view of the rotor 116. The rotor 116 has a rotor core assembly with several rotor teeth 124 distributed in a circumferential direction, defining the poles of the rotor. The rotor core assembly can be designed as a laminated stack of sheet metal parts, for example, made of steel. The rotor teeth 124 each extend radially from an inner ring 122, which is attached to the rotor shaft 119 (not shown in detail here). Fig. 12) is fixed in a rotationally fixed manner, extends outwards, and is radially bounded on the outside by a pole shoe 126, which is formed integrally with the associated rotor tooth 124 and also with the inner ring 122. An axial opening 120 for receiving the rotor shaft 119 is formed in the inner ring 122, the rotor shaft 119 defining an axis of rotation 118 of the electric motor 102. The pole shoes 126 each have an arc shape that is symmetrical with respect to the associated rotor pole 124 (or about a radial center line of the rotor pole 124). A longitudinal groove 128 is formed between adjacent rotor teeth 124, extending radially outwards from a groove base 132 to an intermediate gap 130 between the pole shoes 126 of the associated rotor tooth pair. Laterally, the longitudinal groove 128 is defined by side surfaces 134, 136 of the rotor teeth 124.The rotor teeth 124, including the pole shoes 126, and the inner ring 122 form the rotor core assembly of the rotor 116, which surrounds the rotor shaft 119 in a rotationally fixed manner.

[0038] During operation, the current flowing through the rotor windings generates heat in the rotor 116. This heat must be effectively dissipated to the environment to prevent overheating of the rotor 116 and the resulting impairment of the functionality of the entire electric motor 102. In the so-called "wet runner" principle, the electric motor 102, including the air gap between the stator and the rotor 116, is circulated with a liquid coolant, such as oil. Although this allows for direct thermal coupling between the components installed in the electric motor 102 and the coolant, the coolant or oil entering the air gap causes drag losses, which are problematic for torque generation and transmission. In the so-called "dry runner" principle, the liquid coolant or oil does not flow through the air gap, thus avoiding these drag losses.It is essential to adequately seal the rotor 116 against the coolant both axially and radially to prevent the coolant from penetrating the air gap.

[0039] According to the invention, a method for sealing and / or caulking the rotor 116 is therefore proposed, which is described with reference to the following figures.

[0040] Fig. Figure 3 shows a schematic and purely exemplary representation of a laminated lamination stack 117 of the rotor core assembly in a side view. The laminated lamination stack 117 is shown during a process step in which the rotor 116 or the rotor core assembly is provided. Two rotor teeth 124 are in Fig. 3 shows that each rotor winding group 138, 140 comprises a plurality of rotor windings wound around the respective rotor tooth 124. This increases the volume of the longitudinal groove 128 (see Fig. 2) partially occupied by the rotor windings, whereby a gap 142, narrower than the longitudinal slot 128, is now formed between the two rotor winding groups 138, 140, extending radially outwards from the slot base 132 to the intermediate gap 130 between the pole shoes 126. An end-face winding head of the respective rotor winding group 138, 140 is attached to a winding support 144, which is arranged at an axial end of the rotor core assembly 116.

[0041] Fig. Figure 4 shows a schematic top view of the laminated sheet metal stack 117, with two end-face tool halves 201, 202 of an end-face tool arrangement for forming a closure element 146 positioned on two opposite end faces 182, 184 of the sheet metal stack 117. A first end-face tool half 201, in which a sprue 203 for introducing a polymer is formed, is fixedly positioned on a first end face 182 of the sheet metal stack 117. A second end-face tool half 202 is movably positioned on a second end face 184 of the sheet metal stack 117, axially opposite the first end face 182. The polymer is selected for use in a forming process to form the closure element 146. The forming process is preferably a casting process, such as an injection molding process, and / or a pressing process, such as an injection molding process.The polymer for the closure element 146 is preferably a polymeric molding compound, in particular a thermosetting or thermoplastic plastic, or alternatively a thermoplastic elastomer. The end-face tool halves 201, 202 of the end-face tool arrangement thus define the closure element 146 to be molded in the axial direction or in length.

[0042] Fig. Figure 5 shows a schematic representation of the laminated sheet metal stack 117 in a further side view. In addition to the end-face tool arrangement, an outer tool core 206 and an inner tool core 207 are positioned in the area of ​​the gap 130 between the pole shoes 126 of the adjacent rotor teeth 124. An axially flat radial gap is defined between the outer tool core 206 and the inner tool core 207, which is bounded in the axial direction by the end-face tool halves 201, 202 of the end-face tool arrangement. The polymer is introduced into the radial gap via the sprue 203, with two gates 204, 205, between which the sprue 203 is arranged, also being provided on the first end-face tool half 201.

[0043] Fig. Figure 6 shows a schematic representation of the laminated sheet metal stack 117 in a side view after the forming of the closure element 146 with the polymer and by means of the forming process. The closure element 146 is arranged connectingly between the pole shoes 126 of the associated rotor tooth pair. The closure element 146 has a radial outer surface 151 and a radial inner surface 148. An elongated cavity 150 is defined between the radial inner surface 148 of the closure element 146 and the groove base 132.

[0044] Fig. 7 and Fig. Figure 8 shows the locking element 146 in a schematic side view according to one embodiment. In both embodiments, a lateral positive locking 186 is provided between the locking element 146 and the respective pole shoe 126. The lateral positive locking 186 is achieved by recessing, in particular by punching, laser cutting and / or etching, the pole shoes 126 in an edge region.

[0045] In the Fig. In the embodiment shown in Figure 7, a lateral projection 149 is formed on the locking element 146, which projects into the recessed edge area of ​​the respective pole shoe 126 in a form-fitting and interlocking manner.

[0046] In the Fig. In the alternative embodiment shown in Figure 8, conversely, a nose shape is formed in the edge region of the pole shoes 126, which is positively engaged and interlocked between two lateral projections 149 of the locking element 146. These measures ensure a particularly reliable radial seal against coolant circulating inside the rotor core assembly. Furthermore, this arrangement and shaping of the edge-side nose shape of the pole shoes 126, as well as the two lateral projections 149 that at least partially encompass this nose shape, ensures a secure hold of the locking element 146 on the pole shoes 126, even if the material of the locking element 146 shrinks slightly after the forming process.

[0047] In the Fig. 9 and Fig. In the further alternative embodiments shown in Figure 10, the cross-section of the locking element 146 and the design of the positive locking mechanism 186 each differ from the one shown in Figure 10. Fig. 8. (Execution shown.)

[0048] The closure element 146 can be formed from a single polymer along its entire length. However, this is not a limitation for the present invention.

[0049] Fig. Figure 11 shows a schematic top view of the closure element 146 according to a further embodiment, which comprises two axial end sections 146a, 146b and an intermediate section 146c arranged between them. The intermediate section 146c can be formed from a first polymer that is different from a second polymer from which the axial end sections 146a, 146b are formed. Alternatively or additionally, all three sections 146a, 146b, 146c can each be formed from one of three different polymers. Possible combinations of the polymers are, for example, thermosets, thermoplastics, and thermoplastic elastomers.

[0050] Fig. Figure 12 shows a schematic perspective view of the rotor 116. The rotor 116 is shown in a further process step for impregnating the rotor windings by a separate forming process, which is distinct from the forming process used to shape the closure element 146. For this purpose, several molded parts 152, corresponding to the number of elongated cavities 150, which are adapted to the elongated cavities 150 in terms of their shape and volume, are each inserted into one of the elongated cavities 150. In particular, the molded parts 152 penetrate axially through the elongated cavities 150. The molded parts 152 are preferably formed such that their outer dimensions closely approximate the inner dimensions of the elongated cavities 150.Simultaneously, after being inserted into the elongated cavities 150, the molded parts 152 create a gap between them and the respective rotor winding groups 138, 140, the closure element 146, and the groove base 132. Subsequently, the gaps between the molded parts 152 on the one hand and the inner surfaces of the elongated cavities 150 on the other hand are filled with a further molding material by means of the molding process. The molding material for the impregnation is an electrically insulating material (insulating material), preferably a thermosetting material such as resin, or a potting compound. One of the process types already described above with regard to the closure element 146 can be used to form the impregnation 158, 162 (see ). Fig. 13) can be used. Alternatively, a trickle impregnation process can be used instead of the further forming process to impregnate the rotor windings. In this case, however, a tool core 152 is not required.

[0051] Fig. Figure 13 shows a schematic cross-sectional view of the laminated sheet metal stack 117 in this process state, revealing an elongated cavity 154 (exposed after removal of the associated tool core 152 in the case of the forming process). The elongated cavity 154 extends circumferentially between two facing impregnation surfaces 156, 157, within which the rotor winding groups 138, 140 attached to the adjacent rotor teeth 124 are enclosed. In the radial direction, the elongated cavity 154 extends between the closure element 146 and the groove base 132 of the longitudinal groove 128, in particular between an outer surface layer 166 on the closure element 146 and an inner surface layer 168 on the groove base 132 of the longitudinal groove 128, which are created by applying the impregnation material (or the further polymer) to the radial inner surface 148 of the closure element 146 or the groove base 132.The impregnation 158, 162 connects the individual rotor windings of the respective rotor winding group 138, 140 together, so that the rotor windings are formed together to form a winding unit and are simultaneously electrically effectively insulated from each other and from the environment.

[0052] Fig. Figure 14 shows a schematic representation of the laminated sheet metal stack 117, with a slot closure wedge 170 being received in the elongated cavity 154. The slot closure wedge 170 is inserted into the previously formed elongated cavity 154 in a single process step. The slot closure wedge 170 corresponds to the tool core 152 used in terms of its geometric design and external dimensions. A coolant channel 172 for axial coolant guidance is also formed in the slot closure wedge 170.

[0053] Furthermore, a sealing ring 188 is attached to the end face 182, 184 of the rotor core assembly or the laminated lamination stack 117. The sealing ring 188 is positioned or attached to the end face 182, 184 as a prefabricated component, or it is designed as an applicable, curable sealant and applied to the end face 182, 184. This is preferably done on both opposing end faces 182, 184 of the rotor core assembly. This measure provides additional axial sealing of the rotor 116.

[0054] Fig. Figure 15 shows a schematic representation of the rotor 116 in an exemplary perspective view. The rotor 116 is shown in a process step in which two balancing discs 174 are attached to the opposite end faces 182, 184 of the rotor 116 for axial sealing. For the sake of clarity, details of the rotationally symmetrical balancing discs 174 are not shown here. Reference symbol list 100 at least partially electrified vehicles 102 Electric motor (externally excited synchronous motor) 104 drive battery 106 DC / AC inverters 108 Control unit 110 rear axle 112 gearboxes 114 rear wheels 116 Rotor 117 laminated sheet metal package 118 Rotation axis 119 Rotor shaft 120 opening 122 inner ring 124 rotor teeth 126 Polschuh 128 longitudinal groove 130 gap 132 Groove 134 side area 136 side area 138 Rotor winding group 140 Rotor winding group 142 Gap 144 coil carriers 146 Locking element 146a axial end section 146b axial end section 146c Intermediate Section 148 radial inside 149 lead 150 elongated cavity 151 radial outer side 152 Tool core 154 elongated cavity 156 Impregnation surface 157 Impregnation surface 158 Impregnation 162 Impregnation 166 outer surface layer 168 inner surface layer 170 Groove locking wedge 172 Coolant channel 174 Balancing disc 182 Front 184 Front 186 lateral form fit 188 Sealing ring / sealant 201 Tool element, end-face tool half 202 Tool element, end-face tool half 203 Gate channel 204 Section 205 section 206 Tool element, outer tool core 207 Tool element, inner tool core

Claims

A method for sealing and / or caulking a rotor (116) for an electric motor (102), which is in particular designed as an externally excited synchronous motor, comprising: - providing a rotor (116) having a rotor core assembly that can be fixed to a rotor shaft (119) in a rotationally fixed manner, wherein the rotor core assembly has several rotor teeth (124) distributed in a circumferential direction, wherein an axial longitudinal groove (128) is formed between adjacent rotor teeth (124), and wherein a rotor winding group (138, 140) is arranged around each of the rotor teeth (124); - forming a sealing element (146) for closing and sealing an intermediate gap (130) between two opposing pole shoes (126) of two adjacent rotor teeth (124), such that the sealing element (146) extends in an axial direction connecting the pole shoes (126) to form an elongated cavity (150) to define for the purpose of receiving a slot closure part (170);wherein the closure element (146) is formed from a polymer by means of a forming process using at least one tool element (201, 202, 206, 207) that forms at least part of the shape. Method according to claim 1, wherein the forming tool element is designed as an end-face tool half (201, 202) and / or as an outer tool core (206) and / or as an inner tool core (207). Method according to claim 2, wherein at least one of the end-face tool halves (201, 202) forms a unit with one of the tool cores (206, 207), preferably with the inner tool core (207). Method according to claim 2 or 3, wherein an inner tool core (207) or end-face tool halves (201, 202) is / are used to define a radial inner contour of the closure element (146), and / or wherein an outer tool core (206) or end-face tool halves (201, 202) is used to define a radial outer contour of the closure element (146). Method according to one of claims 2 to 4, wherein end-face tool halves (201, 202) are used in combination with the tool cores (206, 207), wherein the end-face tool halves (201, 202) are brought into contact with an end face (182, 184) of the rotor core arrangement, in particular a laminated sheet metal stack (117), during the forming process for axial sealing of the rotor (116) against the introduced polymer. Method according to one of the preceding claims, wherein the forming process is designed such that the closure element (146) comprises two axial end sections (146a, 146b) and an intermediate section (146c) arranged between the axial end sections (146a, 146b). Method according to claim 6, wherein the intermediate section (146c) is formed from a first polymer, wherein the axial end sections (146a, 146b) are formed from a second polymer different from the first polymer. Method according to one of the preceding claims, wherein the forming process comprises a casting process, in particular an injection molding process, a vacuum casting process and / or a pressing process, in particular an injection molding process. Method according to one of the preceding claims, wherein the closure element (146) forms a lateral positive fit with the pole shoes (126) of the adjacent rotor teeth (124) with respect to the cross-section, wherein the method preferably further comprises recessing an edge region of a pole shoe (126), and more preferably of two pole shoes (126) of adjacent rotor teeth (124), in order to introduce the polymer into the recessed edge region during the forming process for shaping the closure element (146). Method according to one of the preceding claims, further comprising impregnating the rotor winding groups (138, 140) with an impregnating material. Method according to one of the preceding claims, further comprising: - removing the tool core (152) after forming the closure element (146); and - inserting a groove closure part (170) into the elongated cavity (150). Method according to one of the preceding claims, further comprising forming a groove closure part (170) for closing the elongated cavity (150) with a further polymer by a further forming process. Method according to one of the preceding claims, further comprising attaching a sealing ring or a sealing compound (188) to the end face of the rotor core assembly after inserting a groove closure part into the elongated cavity (150). Rotor (116) for an electric motor (102), in particular an externally excited synchronous motor, wherein the rotor (116) is sealed and / or sealed by means of the method according to one of claims 1 to 13. Electric motor (102), in particular an externally excited synchronous motor, for an at least partially electrified vehicle (100), comprising the rotor (116) according to claim 14. At least partially electrified vehicle (100) comprising an electric motor (102), in particular an externally excited synchronous motor, according to claim 15.

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