Production method for making tight or sealing a rotor with rotor winding groups

Abstract

The invention relates to a method for making tight or sealing a rotor (116), comprising: providing a rotor (116), having a rotor core assembly that can be secured to a rotor shaft (119) for conjoint rotation, wherein the rotor core assembly has multiple rotor teeth (124) distributed in a circumferential direction with an axial longitudinal groove (128) between them, and a rotor winding group (138, 140) wound around each individual rotor tooth; providing a closure element (146) to close each of the gaps between the pole shoes (126) of two adjacent rotor teeth (124) so that the closure element (146) connects the pole shoes (126); impregnating the rotor winding groups (138, 140) with sealing material using at least one core forming an elongate cavity (154); said cavity extends in the circumferential direction between two mutually opposed impregnation surfaces (156, 157) of the impregnation material (158, 162), which are enclosed within the rotor winding groups (138, 140) attached around rotor teeth (124) and in the radial direction between the closure element (146) and the base (132) of the longitudinal groove (128).

Description

[0001] Method for sealing and / or sealing a rotor for an electric motor with improved rotor sealing

[0002] 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.

[0003] Fully electric vehicles and hybrid vehicles are well known from the prior art. These electric vehicles are powered 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 rotating field on the stator side on the other generates a torque that sets the rotor in rotation.

[0004] 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 tooth 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. During operation, the current applied to the rotor coils generates heat in the rotor. Insufficient cooling can lead to overheating of the rotor and consequently to impairment of the functionality of the entire electric motor.Therefore, it is essential to effectively cool the rotor with a coolant. Various cooling concepts for rotors are known from the prior art. In the so-called "wet runner principle," the entire electric motor is supplied 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 have a particularly negative impact on torque generation 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 prior art 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 insufficient, so there is a risk that the liquid coolant or oil can easily enter the air gap and cause drag losses. Furthermore, in rotors known from the prior art, the rotor windings are typically impregnated using a trickle impregnation process. However, the material used for this purpose has a comparatively low thermal conductivity, so heat dissipation from the rotor windings is only partially effective.

[0007] The object of the present invention is therefore to provide a method for sealing and / or caulking the rotor, thereby at least partially overcoming the aforementioned disadvantages. This 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 relating to the method also apply to the rotor, the electric motor, and the vehicle according to the invention.

[0008] 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 comprises a rotor shaft, which defines the axis of rotation, and a magnetically acting rotor core assembly fixed to the rotor shaft. This assembly can be designed as an arrangement of at least one, but preferably several, laminated sheet metal parts or stacks, preferably made of steel. 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, for example a reduced / single-stage gearbox.

[0009] The method for sealing and / or caulking the rotor comprises a first process step in which the rotor is provided. The rotor has a rotor core assembly that can be fixed to a rotor shaft in a rotationally fixed manner. The rotor core assembly comprises several rotor teeth distributed circumferentially, in particular uniformly, around which a rotor winding group (or a rotor winding package) with several rotor windings is arranged. Two pole shoes are formed on a radial end section of each rotor tooth, with an intermediate gap formed between two opposing pole shoes of two adjacent rotor teeth. Thus, a longitudinal groove extending radially outward from a groove base to the intermediate gap between the pole shoes is formed between adjacent rotor teeth.

[0010] The method for sealing and / or sealing 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 sealing element is preferably made of a plastic material, in particular a thermoplastic material.

[0011] Preferably, the locking element has a cross-sectional contour that forms a positive fit with the pole shoes of the adjacent rotor teeth. This positive fit can be achieved, for example, by interlocking teeth between the first teeth of the locking element and the second teeth of the pole shoes. This measure results in improved sealing of the rotor in the radial direction.

[0012] The method for sealing and / or calibrating the rotor comprises a further process step in which the rotor winding groups attached to the adjacent rotor teeth are impregnated with a potting material by a molding process using at least one molded part that radially limits the impregnation. During impregnation, an elongated cavity is formed by a subsequently removable core, extending circumferentially between two opposing impregnation surfaces. The rotor windings of the corresponding rotor winding group are enclosed within each impregnation surface. Furthermore, the elongated cavity extends radially between the sealing element and the bottom of the longitudinal groove. The molding process is designed to form the potting material into a geometric shape defined by the molded part and a core.In this process, at least one core is preferably positioned near the inner walls of the elongated cavity, particularly near the rotor windings of the respective rotor winding group. In this case, a gap forms between the inner walls of the elongated cavity on the one hand and the surface of the core on the other. The potting material is then introduced into this gap using a molding process and also penetrates the interior of the respective rotor winding group, particularly into the spaces between adjacent rotor windings. In this way, the rotor windings are mechanically and stably connected to one another, forming a solid winding unit. This improves heat transfer from the rotor windings to the surrounding environment, especially the rotor's laminated core and the components located between adjacent rotor teeth or pole shoes.The potting material is preferably an insulating material, so that the impregnation of the rotor winding groups resulting from the molding process also has an electrically insulating effect.

[0013] The method described above, and which will be further specified below, relates to a single closure element associated with a longitudinal groove, a rotor tooth 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 tooth 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 tooth / pole shoe pairs, and elongated cavities, so that the sealing and / or cavities can be performed with high process efficiency.

[0014] The method can additionally include providing the rotor shaft. This is preferably done before providing the locking element, in particular such that the rotor core assembly is fixed to the rotor shaft in a rotationally fixed manner. Alternatively, the rotor shaft can be provided after providing the locking element or after impregnating the rotor winding assemblies. 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.By impregnating the rotor windings with the potting material during the molding process, improved heat dissipation is achieved between the rotor windings and their environment, particularly the coolant circulating in the rotor according to the flooded rotor design, thanks to the comparatively high thermal conductivity of the potting material used. This is achieved, for example, compared to the trickle method. Furthermore, according to the invention, improved sealing of the rotor is achieved using the molding process compared to the trickle method.

[0015] According to an exemplary embodiment, the sealing element is a prefabricated component that is inserted, or in particular, slid into, the gap between the pole shoes of adjacent rotor teeth. This measure enables a simplified sealing method for the rotor. In particular, several sealing elements can be inserted or slid into multiple gaps on the pole shoe pairs simultaneously, which increases manufacturing efficiency. Furthermore, the geometric characteristics of the rotor, especially the pole shoes, the longitudinal grooves, and the rotor windings, can be taken into account during the prefabrication of the sealing element. In this way, the design of the sealing element can be selected to provide a reliable seal of the rotor, particularly in the radial direction, against the circulating coolant.

[0016] According to another exemplary embodiment, the closure element is formed by the forming process. For example, the closure element can be formed in parallel with the impregnation of the rotor winding assemblies, with the potting material used for the impregnation in the forming process simultaneously serving to form the closure element. Alternatively, the impregnation of the rotor winding assemblies can take place after the closure element has been formed. In the latter case, the closure element is first formed using the forming process and a corresponding mold part (or a set of corresponding mold parts), after which the impregnation is carried out.In both process steps, the same potting material can be used, or alternatively, two different potting materials can be used to meet the different material requirements of the impregnation on the one hand and the sealing element on the other. This ensures reliable adhesion of the sealing element to the pole shoes of the adjacent rotor teeth. Furthermore, this measure promotes a positive-locking connection between the sealing element and the rotor teeth, which improves the radial sealing of the rotor.

[0017] According to another exemplary embodiment, the forming process comprises a pressing process or an injection molding process. The injection molding process enables the production of complex and precise shapes with a high degree of detail. It is particularly suitable for the impregnation or encapsulation of sensitive electronic components by forming a seamless, protective layer. Furthermore, it offers high flexibility in material selection, with various resins or epoxy molding compounds being suitable as potting materials.

[0018] According to another exemplary embodiment, the shaping process includes vacuum potting. Here, all components are processed in a single step within a mold, simplifying the process. This requires fewer work steps, resulting not only in time efficiency but also in the use of a simple potting compound and protective layers for the rotor windings to be impregnated and the areas of the rotor to be sealed.

[0019] According to another exemplary embodiment, the potting material can comprise a resin material, in particular an epoxy resin. Such potting materials are particularly suitable for the molding process for impregnating the rotor windings and for sealing the rotor due to their comparatively high thermal conductivity in combination with their low viscosity and mechanical properties.

[0020] According to another exemplary embodiment, the molded part has a wedge-shaped cross-section with a radially inwardly directed taper, the method further comprising axially inserting the molded part into the elongated cavity between the adjacent rotor teeth before impregnating the rotor winding groups. This measure enables the precise formation of a similarly wedge-shaped cavity for receiving the slot closure wedge in a simple manner.

[0021] According to another exemplary embodiment, the core and / or the potting material are selected to create contact, preferably line contact, between the outermost winding layer of the respective rotor winding group and the elongated cavity during the molding process for impregnating the rotor windings. This is achieved, for example, by ensuring that the core's cross-section corresponds to the elongated cavity, particularly in the areas of the rotor windings, except for a minor difference in its external dimensions. Thus, a gap is formed between the molded part and the outermost rotor windings of the respective rotor winding group, the thickness of which varies according to the tolerance of the rotor winding and is minimal when the core is in line contact with the winding. The potting material, from which the impregnation is formed, enters this gap during the molding process.This measure, while simultaneously ensuring electrical insulation of the rotor windings, reduces the thermal resistance of the impregnation to the minimum possible, thus enabling better heat transfer from the impregnated rotor windings to the environment, particularly to the circulating coolant. Furthermore, cost savings are achieved through the reduced quantity of potting material used to impregnate the rotor windings.

[0022] According to another exemplary embodiment, the molded part, the core, and / or the potting material are selected to form a surface layer of the potting material at the base of the longitudinal groove and / or on the inner surface of the closure element opposite the groove base during the molding process. This is achieved, for example, by ensuring that the core's cross-section corresponds to the elongated cavity, particularly in the areas of the groove base and the closure element, except for a minor difference in external dimensions. The surface layer on the closure element ensures a particularly reliable and precise seal of the rotor in the radial direction. Overall, the surface layer on both the closure element and the groove base enables the secure engagement of the groove closure wedge in the elongated cavity. According to another exemplary embodiment, the closure element has a ribbed structure.The rib structure is preferably deformable in the axial direction, and the sealing element is longer than the rotor core assembly to compensate for any potential length difference between the sealing element and the rotor tooth during the forming process for impregnating the rotor windings, thus ensuring a reliable seal to the molded part. The axial force required for the axial deformation is provided by contacting tool surfaces.

[0023] According to a further exemplary embodiment, the method further comprises removing the core after impregnation of the rotor winding assemblies and inserting a slot-locking wedge into the elongated cavity. After removing the core, the elongated cavity is prepared for inserting the appropriate slot-locking wedge. Preferably, the core is adapted to the slot-locking wedge with respect to its geometric design and external dimensions.

[0024] According to another exemplary embodiment, the slot closure wedge is used as a core during the impregnation of the rotor winding groups. Thus, even after the impregnation of the rotor windings of the respective rotor winding group, the core remains in the elongated cavity and fulfills or takes over the function of the slot closure wedge. In this way, the removal of the core and the insertion of a separate slot closure wedge are eliminated, which greatly simplifies the process and significantly reduces the time and costs involved.

[0025] According to a further exemplary embodiment, the locking element can be designed such that its axial length can be adapted to the actual length of the rotor stack formed by the rotor's lamination stacks, for example, by means of deformation zones which can be achieved by means of material weakening and / or sectionally elastic materials in the base body of the locking element. The locking element can be manufactured, for example, by a two-component injection molding process, wherein a hard component forms the base body and a soft component forms the deformation zones. According to a further exemplary embodiment, the locking element can be designed such that a positive fit can be created between the locking element and an outer surface layer of the potting material.For this purpose, the locking element can have features, particularly on its side facing the interior of the rotor when installed, which can be designed, for example, as a longitudinal web with openings and / or as a T-shaped longitudinal web and / or as recesses.

[0026] 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.

[0027] 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 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.

[0028] 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).

[0029] 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.

[0030] The invention is explained below with reference to examples using the embodiments shown in the figures. The figures show:

[0031] Fig. 1 shows a schematic representation of a vehicle comprising an electric axle drive with an electric motor;

[0032] Fig. 2 shows a schematic representation of a rotor core arrangement of the electric motor in a cross-sectional view;

[0033] Fig. 3 shows a side view of a laminated sheet metal stack of the rotor core assembly during a process step for providing the rotor core assembly;

[0034] Fig. 4 shows a side view of the laminated lamination stack of the rotor core assembly during a process step for providing a closing element to close an intermediate gap between two pole shoes of adjacent rotor teeth of the rotor core assembly;

[0035] Fig. 5 shows a perspective view of the rotor during a process step for impregnating rotor windings in the rotor core arrangement by a forming process;

[0036] Fig. 6 shows a side view of the laminated sheet metal stack of the rotor core assembly after impregnation, showing an elongated cavity;

[0037] Fig. 7 shows a cross-sectional view of the elongated cavity;

[0038] Fig. 8 shows a side view of the laminated lamination stack of the rotor core assembly during a process step for providing a slot closure wedge in the elongated cavity; Fig. 9 shows a schematic perspective view of the rotor during a process step for attaching two end-face balancing discs for axial sealing of the rotor.

[0039] Fig. 10 shows a further embodiment of a locking element in a perspective view;

[0040] Fig. 11 shows a top view of the rotor of an electric motor with the locking element according to Fig. 10;

[0041] Fig. 12 shows a further embodiment of a locking element in a perspective view;

[0042] Fig. 13 shows a top view of the rotor of an electric motor with the locking element according to Fig. 12;

[0043] Fig. 14 shows a further embodiment of a locking element in a perspective view;

[0044] Fig. 15 shows a representation of the locking element according to Fig. 14 in a different perspective view;

[0045] Fig. 16 shows a further embodiment of a locking element in a perspective view;

[0046] Fig. 17 shows a representation of the locking element according to Fig. 16 in a different perspective view;

[0047] Fig. 18 shows a further embodiment of a locking element in a perspective view.

[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. 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 here) with several phase strands arranged as stator windings and a rotor 116 (see Fig. 2) comprising several electrically conductive rotor windings.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. Specifically, several phase currents, preferably sinusoidal and phase-shifted, are generated for the stator phase strands by opening and closing several power switches integrated into the inverter 106. These phase currents are fed into each of the stator phase strands, creating a rotating magnetic field inside the stator. The rotor 116, or the rotor windings, are energized with 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.

[0049] Fig. 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. The rotor teeth 124 extend radially outwards from an inner ring 122, which is fixedly attached to the rotor shaft 119 (not shown in detail here, see Fig. 9), and are 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 is formed in the inner ring 122 for receiving the rotor shaft 119, the rotor shaft 119 defining an axis of rotation 118 of the electric motor 102. The pole shoes 126 each have an arc shape which is symmetrical with respect to the associated rotor tooth 124 (or about a radial center line of the rotor tooth 124).Between adjacent rotor teeth 124, a longitudinal groove 128 is formed, extending radially outwards from a groove base 132 to an intermediate gap 130 between the associated pole shoes 126. 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 a rotor core assembly of the rotor 116, which surrounds the rotor shaft 120 in a rotationally fixed manner.

[0050] During ferry 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 supplied 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 to prevent the coolant from entering the air gap.

[0051] 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.

[0052] Fig. 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 visible in Fig. 3, each of which has a rotor winding group 138, 140 comprising a plurality of rotor windings attached to or wound around the respective rotor teeth 124. This partially occupies the volume of the longitudinal groove 128 (see Fig. 2), forming a narrower gap 142 between the two rotor winding groups 138, 140, which extends radially outwards from the bottom of the groove 132 to the intermediate gap 130 between the pole shoes 126.A front-end winding head of the respective rotor winding group 138, 140 is attached to and thereby held on a winding carrier 144, which is arranged on the front of the rotor 116.

[0053] Fig. 4 shows a further schematic and purely exemplary representation of the laminated lamination stack 117 of the rotor core assembly in a side view. The laminated lamination stack 117 is shown in a process step in which a sealing element 146 is provided to close an intermediate gap 130 between the pole shoes 126 of the adjacent rotor teeth 124. In the example shown here, the elongated sealing element 146, which is already available as a prefabricated component, is inserted axially into the intermediate gap between the pole shoes 126. The sealing element 146 is adapted to the outer contour of the respective pole shoes 126 in its edge regions facing them, such that a positive-locking connection to the pole shoes 126 is provided after the sealing element 146 is inserted into the intermediate gap 130.The closure element 146 is preferably at least axially compressible, so that if the length of the closure element 146 is selected to be slightly greater than the length of the rotor core arrangement, the closure element 146 can be compressed axially approximately by two opposing tool surfaces in order to achieve a reliable axial seal based on the longitudinal tolerance.

[0054] The attachment of the locking element 146, as shown schematically in Fig. 4, results in an elongated cavity 150, which extends axially between the rotor winding groups 138, 140 and radially between the groove base 132 and an inner surface 148 of the locking element 148.

[0055] Fig. 5 shows a schematic perspective view of the rotor 116. The rotor 116, which has a rotor stack composed of several laminated cores 117, is shown in a process step for impregnating the rotor windings by a forming process. For this purpose, several cores 152, corresponding to the number of elongated cavities 150, which are adapted to the elongated cavities 150 in terms of shape and volume, are each inserted into one of the elongated cavities 150. In particular, the cores 152 penetrate through the elongated cavities 150. The cores 152 are specifically designed such that their outer dimensions closely approximate the inner dimensions of the elongated cavities 150. At the same time, the cores 152, after being inserted into the elongated cavities 150, allow a gap to the respective rotor winding groups 138, 140, the locking element 146 and the groove base 132.The spaces between the cores 152 on the one hand and the inner surfaces of the elongated cavities 150 on the other are then filled with a potting material using a molding process. The potting material is an electrically insulating material, preferably a resin such as epoxy resin. Various molding processes are conceivable, in particular casting, vacuum potting, or pressing, such as injection molding. The potting material introduced in this way also penetrates the interior of the respective rotor winding group 138, 140 and connects the individual rotor windings to one another. This results in an impregnation 158, 162 or encapsulation of the rotor windings, so that the latter are formed together into a winding unit and simultaneously electrically insulated from each other and from the environment.

[0056] After the forming process has been carried out, in particular after the impregnation of the rotor windings, the cores 152 are removed from the rotor 116. Fig. 6 shows a schematic side view of the laminated lamination stack 117 of the rotor core assembly in this process state, showing an elongated cavity 154. Fig. 7 shows another schematic cross-sectional view of the elongated cavity 154. 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 base of the groove 132 of the longitudinal groove 130, specifically between an outer surface layer 166 on the closure element 146 and an inner surface layer 168 at the base of the groove 132 of the longitudinal groove 128. Incidentally, Fig. 7 shows an interlocking connection between the edge regions of the closure element 146 on the one hand and the respective pole shoe 126 on the other. As shown purely by way of example and schematically in Fig. 7, the impregnation surfaces 156, 157 run in sections in a straight line corresponding to the outermost rotor windings 160, 164 (or winding layers) of the respective rotor winding group 138, 140, with a radially inwardly directed taper, such that the elongated cavity 154 has a substantially "Y"-shaped cross-section. This enables line contact between the outermost rotor windings 160, 164 and the elongated cavity 154.

[0057] Fig. 8 shows a schematic representation of the laminated lamination stack 117 of the rotor core assembly in an exemplary side view. The laminated lamination stack 117 is shown during a process step in which a slot closure wedge 170 is inserted into and received in the elongated cavity 154. The slot closure wedge 170 is adapted to the molded part 152 used with regard to its geometric design and external dimensions. The slot closure wedge 170 is preferably dimensioned slightly larger than the core 152, for example by a percentage that corresponds to and does not exceed the degree of deformability of the potting material 150.This allows for a particularly secure fit of the groove closure wedge 170 in the elongated cavity 154, without affecting the impregnation 158, 162 and the material coatings 166, 168, which are formed from the casting material used in the molding process and are located in the area of ​​the groove base 132 and / or the closure element 146. The groove closure wedge 170 also incorporates a coolant channel 172 for axial coolant guidance.

[0058] Fig. 9 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 of the rotor 116 for axial sealing. The axially deformable sealing elements 146, or rather their ribbed structures, ensure a particularly reliable axial seal to the balancing disc 174 after the forming process. For the sake of clarity, details of the rotationally symmetrical balancing discs 174 are not shown here. Although the sealing element 146 is described above as a prefabricated component, it can alternatively be formed using the forming process.This can be done, for example, in parallel with the impregnation of the rotor winding groups 138, 140, by simultaneously using the potting material from which the impregnation 158, 162 is formed in the molding process to form the locking element 146. Alternatively, the impregnation of the rotor winding groups 158, 162 can take place after the formation of the locking element 146. This means that the locking element 146 is first formed with a suitable tool (or a set of suitable tools), after which the impregnation of the rotor windings takes place. In both process steps, the same potting material can be used, or alternatively, two different potting materials can be used to meet the different material property requirements of the impregnation 158, 162 on the one hand and the locking element 146 on the other.

[0059] Alternatively or additionally, the cores 152 are not removed after impregnation of the rotor winding groups 138, 140 and are instead used as slot-locking wedges. Thus, the core 152 remains in the associated elongated cavities 154 even after impregnation of the rotor windings of the respective rotor winding group 138, 140 and continues to function as slot-locking wedges. This eliminates the need to insert separate slot-locking wedges into the rotor 116, which greatly simplifies the process and significantly reduces the time and costs involved.

[0060] Figures 10 to 18 show various advantageous embodiments of the locking element 146.

[0061] The closure element 146 shown in a perspective view in Fig. 10 has an elongated base body 176 in the center of which a deformation zone 178 is arranged. The deformation zone 178 can be designed as a weakening of the material, for example as recesses, optionally in combination with ribs, and allows the base body 176 to change in length when an axial force is applied. In modified embodiments not shown here, the deformation zone 178 can also be arranged at other locations on the base body 176 and / or several deformation zones 178 can be arranged in the base body 176. Fig. 11 shows a top view of several closure elements 146 described above in their installed state in a rotor 116.The axial length of the installed locking elements 146 corresponds to the total length of the lamination stacks 117 assembled to form the rotor stack between the winding carriers 144, whereby the deformation area 178 allows the length of the base body 176 to be adjusted to this predetermined total length.

[0062] The closure element 146 shown in a perspective view in Fig. 12 also has an elongated base body 176, at each end of which a deformation area 178 is arranged. In this embodiment, the deformation areas 178 can be made of an elastic material and allow the base body 176 to change length when an axial force is applied. The closure element 146 designed in this way can, for example, be manufactured using a two-component injection molding process, wherein a hard component forms the base body 176 and a soft component forms the deformation areas 178. In modified embodiments not shown here, the deformation areas 178 can also be arranged at other locations on the base body 176 and / or only one such deformation area 178 or more than two such deformation areas 178 can be arranged in the base body 176.

[0063] Fig. 13 shows a top view of several previously described locking elements 146 installed in a rotor 116. The axial length of the installed locking elements 146 corresponds to the total length of the laminated cores 117 assembled to form the rotor stack between the winding carriers 144, with the deformation range 178 allowing the length of the base body 176 to be adjusted to this predetermined total length.

[0064] The closure element 146, shown in two different perspective views in Figures 14 and 15, also has an elongated base body 176, which, on its side facing the interior of the rotor 116 in the installed state, has a longitudinal web 180. The longitudinal web 180 has several openings 182, which, during the impregnation process described in detail above, can be penetrated by the potting material of the outer surface layer 166 shown in Figure 7, thus forming a positive connection between this surface layer 166 and the closure element 146.

[0065] The previously described positive locking between the closure element 146 and the outer surface layer 166 of the potting material is also achieved in the embodiment of the closure element 146 shown in two different perspective views in Figures 16 and 17. Here, the elongated base body 176 has a T-shaped longitudinal rib on its side facing the interior of the rotor 116 in the installed state. During the impregnation process with the potting material of the outer surface layer 166 shown in Figure 7, as described in detail above, this rib is surrounded by the potting material, thus creating this positive locking.

[0066] This positive locking is also achieved with the last embodiment of the closure element 146, shown in a perspective view in Fig. 18, by the fact that the elongated base body 176 of the closure element 146 has several pocket-shaped recesses 186 on its side facing the interior of the rotor 116 in the installed state, which are filled by the potting material during the impregnation process described above with the outer surface layer 166 shown in Fig. 7, thus creating this positive locking.

[0067] It goes without saying that the features of all the previously described embodiments can be combined with each other, provided that this is technically feasible and makes sense.

[0068] Reference symbol list: at least partially electrified vehicle, electric motor (externally excited synchronous motor), traction battery

[0069] DC / AC inverter

[0070] Control unit

[0071] rear axle

[0072] transmission

[0073] rear wheels

[0074] Rotor laminated sheet metal package

[0075] axis of rotation

[0076] Rotor shaft

[0077] opening

[0078] inner ring

[0079] Rotor tooth

[0080] Polschuh

[0081] longitudinal groove

[0082] gap

[0083] Groove base

[0084] side surface

[0085] side surface

[0086] Rotor winding group

[0087] Rotor winding group

[0088] gap

[0089] Wrap carrier

[0090] Closure element radial inner side elongated cavity

[0091] Core elongated cavity

[0092] Impregnation surface Impregnation surface Impregnation outermost rotor winding Impregnation outermost rotor winding outer surface layer inner surface layer Groove locking wedge Coolant channel Balancing disc Base body Deformation area Longitudinal web Opening T-longitudinal web Recess

Claims

1. 23 Patent claims 1. 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) comprising a rotor core assembly which 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), wherein a rotor winding group (138, 140) is arranged around each of the rotor teeth (124); - Providing a closing element (146) for closing an intermediate gap (130) between two opposing pole shoes (126) of two adjacent rotor teeth (124), such that the closing element (146) extends in an axial direction connecting the pole shoes (126); - Impregnating the rotor winding groups (138, 140) with a potting material by a forming process using at least one core (152) to form an elongated cavity (154) which extends in a circumferential direction between two mutually facing impregnation surfaces (156, 157) of an impregnation (158, 162) within which the rotor winding groups (138, 140) attached to the adjacent rotor teeth (124) are enclosed, and in a radial direction between the closure element (146) and a groove base (132) of the longitudinal groove (128).

2. Method according to claim 1, wherein the closure element (146) is a prefabricated component which is inserted, in particular pushed into, the gap (130) between the pole shoes (126) of the adjacent rotor teeth (124).

3. Method according to claim 1, wherein the closure element (146) is formed by the forming method.

4. Method according to claim 1, wherein the shaping method comprises a casting method, in particular a vacuum casting method and / or a pressing method, in particular an injection molding method.

5. Method according to claim 1 or 2, wherein a polymeric mass, in particular a thermosetting molding compound, is used as the potting material.

6. Method according to claim 1 or 2, wherein the potting material comprises a resin material, in particular an epoxy resin, for example an epoxy molding compound.

7. Method according to one of the preceding claims, wherein the core (152) has a wedge-shaped cross-section with a tapering direction directed radially inwards, wherein the method further comprises inserting the core (152) axially into an elongated cavity (150) between the adjacent rotor teeth (124) prior to impregnating the rotor winding groups (138, 140).

8. Method according to one of the preceding claims, wherein the core (152) and / or the potting material are selected to generate a contact, in particular a line contact, of an outermost winding layer (160, 164) of the respective rotor winding group (138, 140) to the elongated cavity (154) in the forming process.

9. Method according to one of the preceding claims, wherein the core (152) and / or the casting material are selected to form a surface layer (166, 168) of the casting material in the forming process at a groove base (132) of the longitudinal groove (128) and / or at an inner side (148) of the closure element (146) opposite the groove base (132).

10. Method according to any of the preceding claims, wherein the closure element (146) has a rib structure, and / or wherein the closure element (146) is at least axially deformable.

11. Method according to claim 10, wherein the closure element (146) can be manufactured using a two-component injection molding process.

12. Method according to one of the preceding claims, wherein the closure element (146) has a contour in the cross-section of its base body (176) which forms a positive fit with the pole shoes (126) of the adjacent rotor teeth (124).

13. Method according to one of the preceding claims, wherein the closure element (146) has in the cross-section of its base body (176) a shape, for example a contour or an undercut, which forms a positive fit with the casting material.

14. Method according to one of the preceding claims, wherein the method further comprises removing the core (152) after impregnating the rotor winding groups (138, 140) and inserting a slot closure wedge (170) into the elongated cavity (154).

15. Method according to one of the preceding claims, wherein the core (152) is used as a slot locking wedge (170) after impregnation of the rotor winding groups (138, 140).

16. 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 15. 26 17. 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 16.

18. At least partially electrified vehicle (100) comprising an electric motor (102), in particular an externally excited synchronous motor, according to claim 17.

Images