Stator having a plug-in coil winding for an electric motor, method for producing a stator, an electric motor having a stator, and a motor vehicle having an electric motor having a stator

Abstract

The invention relates to a stator (1) having a plug-in coil winding (2) for an electric motor for a motor vehicle, the stator comprising plug-in coils, which have conductor elements (7), and comprising a laminated core (4), which forms a wall, and in the wall there are arranged a plurality of stator slots (6) which extend in an axial direction of the stator (1) and in which at least one conductor element (7) is arranged, and slot insulators (5) are arranged on the slot walls (8) delimiting the stator slots (6), and cavities (9) are formed between a slot insulator (5) and the conductor elements (7) and are filled with a cured impregnation material (10). The invention is characterized in that the slot insulators (5) arranged in the stator slots (6) are designed such that liquid impregnation material can be absorbed by the slot insulators before the impregnation material cures, and the slot insulators are arranged in the stator slots (6) such that the slot insulators (5) are penetrated by the cured impregnation material (10) and a distribution of the impregnation material is limited to within a relevant stator slot (6).

Description

[0001] Stator with plug-in coil winding for an electric motor, method for producing a stator, an electric motor with a stator and a motor vehicle with an electric motor with a stator

[0002] The invention relates to a stator with plug-in coil winding for an electric motor according to the preamble of patent claim 1, a method for producing a stator, an electric motor with a stator and a motor vehicle with an electric motor with a stator.

[0003] US 7,034,428 B2 shows an arrangement of rectangular copper hairpin windings for electrical machines, a stator with a substantially cylindrical interior, wherein the stator has a plurality of stator slots and a first plurality of hairpin conductors or hairpin conductor elements arranged in the stator slots in a specific short-pitch arrangement. It is further disclosed that a hairpin plug-in coil insulation is applied to at least one of the first plurality of hairpin plug-in coils before the first plurality of hairpin conductors or hairpin conductor elements are positioned in the stator slots.

[0004] In newer electric motors, particularly those used to power electric vehicles, a stator does not have wire coils wound from copper wire with a circular cross-section to generate magnetic fields. Instead, the magnetic fields in the stator can be generated using a large number of plug-in coils made from flat copper wire, each with a rectangular cross-section, for example. In a stator with plug-in coils, individual conductor elements or copper wires are packed more densely, meaning that an electric motor with a stator with plug-in coils has more copper per volume than an electric motor with a stator with wound wire coils. This increases power and torque for the same motor volume, i.e., power density. Furthermore, a stator with plug-in coils can be cooled more efficiently.The plug-in coils, which can also be referred to as pins, can vary in shape, length, angle and wire cross-section and can be manufactured by bending processes from flat copper wire, i.e. a copper wire with a rectangular or square cross-section. The plug-in coils can have a U-shaped or I-shaped geometry and are inserted into stator slots, particularly in a finished state of the stator. With U-shaped plug-in coils, also called hairpins because of their hairpin-like shape, after insertion all closed sides of the respective hairpins are arranged on one side of the stator and the open ends are on an opposite side of the stator, where they are electrically connected to one another according to a wiring plan, for example by welding.In I-shaped plug-in coils, also called I-pins, which have an elongated rod shape, the ends are connected to each other on both sides of the stator. In a stator with U-shaped plug-in coils, the side on which the closed sides of the plug-in coils are located can be referred to as the winding head. Due to the spatially densely packed arrangement of the plug-in coils, the plug-in coils must be insulated from one another, for example by a current-flow-inhibiting coating or insulation. On the other hand, the plug-in coils must be insulated from a stator laminated core, which forms a wall of the stator, so that current cannot flow through it via the plug-in coils.

[0005] It is an object of the invention to provide a stator for an electric motor of a motor vehicle, a method for producing such a stator, an electric motor with such a stator and a motor vehicle with such an electric motor, so that a particularly high robustness of the stator can be realized.

[0006] This object is achieved according to the invention by a stator with plug-in coil winding for an electric motor for a motor vehicle having the features of patent claim 1, a method for producing such a stator having the features of patent claim 5, an electric motor having such a stator having the features of patent claim 6, and a motor vehicle having such an electric motor having the features of patent claim 7. Advantageous embodiments with expedient further developments of the invention are specified in the remaining claims.A first aspect of the invention relates to a stator with a plug-in coil winding for an electric motor for a motor vehicle, with a plurality of plug-in coils, each having at least one conductor element through which electric current can flow, and with a laminated core which forms a wall delimiting a receiving space designed to accommodate a rotor in a circumferential direction, and in the wall a plurality of stator slots distributed in the circumferential direction are arranged, each extending along an axial direction of the stator and in each of which at least one conductor element is arranged, and a slot insulation is arranged on a respective slot wall at least partially delimiting the respective stator slot, and at least one hollow space is formed between a respective slot insulation and the respective at least one conductor element, which hollow space is at least partially filled with a cured impregnation material.

[0007] In other words, at least one conductor element of a plug-in coil is inserted into each stator slot and is electrically insulated from the laminated core containing the stator slots by the respective slot insulations designed to inhibit current flow. In the finished state, the stator slots are each filled with a cured impregnation material.

[0008] The plug-in coils can be U-shaped or I-shaped, whereby a conductor element in a U-shaped plug-in coil is a limb of the U, which can also be referred to as a leg of the plug-in coil. In an I-shaped plug-in coil, the entire I-shaped plug-in coil can be referred to as a conductor element. The laminated core can be a layered arrangement of a plurality of sheets or laminations, each of which can be made of electrical sheet, an iron-silicon alloy, and each can be 0.1 to 1 mm thick. These individual laminations can be electrically insulated from one another, for example by a powder coating and can be glued or baked when stacked on top of one another to form the laminated core. The laminated core can have a wall that encloses the receiving space, and the wall can be closed in a circumferential direction and open on two opposite sides.A rotor can be inserted into the stator or into the laminated core through one or both open sides. The axial direction can run parallel to an axis of rotation of a rotor that can be inserted into the receiving space. The stator slots can extend in this axial direction and, in particular, can completely penetrate the wall in this axial direction. In other words, the stator slots represent openings in the laminated core that run through the wall. The stator slots are each lined with slot insulation that rests against their respective slot wall. The respective slot insulations can be made of a current-flow-inhibiting material, such as paper, and are intended to prevent current flow between the laminated core and the at least one conductor element arranged or inserted in a respective stator slot when current flows through the at least one conductor element.

[0009] To insert the at least one conductor element into a stator slot or, more generally, to insert the conductor elements into the respective stator slots, a degree of play or clearance is required, i.e. a non-exact correspondence between a cross section or a transverse dimension of the at least one conductor element or of a plurality of conductor elements to be inserted into each stator slot and a corresponding transverse dimension of the stator slot. In other words, each stator slot should be designed such that one or more conductor elements, after being inserted or plugged into a stator slot, are movable in a direction transverse to the axial direction along which the stator slot extends. If the at least one conductor element is plugged into a stator slot, cavities or at least one cavity can form between the respective slot insulation and the respective at least one conductor element as a result of the play.For improved electrical insulation between a respective conductor element and the laminated core, as well as for mechanically fixing the respective conductor elements in the respective stator slots, this cavity is filled with a curable impregnation material after the conductor elements have been inserted or inserted. The impregnation material is introduced or injected in a liquid state and then cures. In other words, impregnation with the impregnation material is also intended to improve the mechanical strength of the at least one conductor element in a stator slot. After curing, the at least one cavity in a stator slot is intended to be filled so that a respective conductor element is immobile in a stator slot. An impregnation resin such as epoxy resin or polyester resin can be used as the impregnation material, for example.The stator is characterized in that the slot insulation arranged in a respective stator slot is designed in such a way that liquid impregnation material can be absorbed by it before it hardens and is arranged in the respective stator slot in such a way that the slot insulation is penetrated by the hardened impregnation material at least in some areas and a distribution of the impregnation material is limited to within the stator slot.

[0010] In other words, the impregnation material, which is liquid upon introduction, is intended to be absorbed or absorbed by the slot insulation arranged therein after introduction into a respective stator slot, thus preventing the still-liquid impregnation material from leaking out. The impregnation material is intended to be held or enclosed by the respective slot insulation until it hardens and after hardening. In particular, it is provided that several conductor elements, each from different plug-in coils, are inserted into a stator slot. The motor vehicle is designed, for example, as a motor vehicle, in particular as a passenger car or as a commercial vehicle. The motor vehicle is preferably an electric vehicle or hybrid vehicle.

[0011] The invention is based on the following findings and observations: It is preferably provided that a plurality of conductor elements of different plug-in coils are arranged in each stator slot. Before the conductor elements are inserted into the respective stator slots, the plug-in coils are braided together. The individual plug-in coils, which are preferably made of flat wire, are varnished before being inserted into the stator or the respective stator slots, i.e. covered with a layer of varnish that inhibits current flow, in order to be electrically insulated from one another. A polyurethane varnish, a polyester-based varnish and / or particularly preferably a polyamideimide varnish can be used as the varnish layer. In order to be able to insert the respective conductor elements better, i.e. particularly efficiently, into the respective stator slots, a cross-section of each stator slot is larger than a cross-section of the conductor elements to be inserted into the respective stator slot.In other words, the conductor elements have play in the stator slot. When the conductor elements are inserted into the respective stator slots, this play can cause cavities so large that an impregnating material introduced in a liquid state cannot be held in the stator slot by capillary action until it hardens. In this case, the impregnating material in the liquid state flows out of the stator slot, for example onto the parts of the conductor elements or plug-in coils that are located outside the stator slots. The impregnating material and a coating or varnish with which the plug-in coils are coated as a whole can have a different temperature behavior than the hardened impregnating material, for example, different thermal expansion coefficients.Particularly during continuous temperature cycling, i.e. when the temperature of the plug-in coils and the impregnation material that may be cured on the plug-in coils, particularly in the area of ​​the winding overhangs outside the stator slots, is heated up and then cooled down again, thermomechanical stresses at the interfaces between the cured impregnation material and the varnish or a varnish layer of the plug-in coils can cause the varnish to tear or flak off the plug-in coils. This can lead to unwanted current flows between the conductor elements and / or between a conductor element and the stator or the laminated core. This can reduce or diminish the efficiency of an electric motor in which the stator may be located.

[0012] The invention thus provides the advantage of providing a particularly robust and / or durable stator. The stator slots can each be slotted on a side facing or toward the receiving space over their entire length in the axial direction—as is known from the prior art—so, for example, they can be open toward the receiving space or fluidly permeable.

[0013] In a further embodiment, the slot insulation is at least partially made of a surface insulating material with an absorbent surface, which is designed to at least partially absorb the impregnating material in a liquid state before the impregnating material hardens, to retain it until hardening, and to at least partially enclose the impregnating material in a hardened state after hardening. In other words, the slot insulation is designed to be able to absorb the liquid insulating material before hardening.For this purpose, the slot insulations can each have, for example, paper as a surface insulation material, which can be covered with felt, textile, fur and / or a sponge on at least one side, preferably on the side facing or pointing towards the stator slot and / or the at least one conductor element arranged in a respective stator slot, i.e. the side facing the conductor element(s) in an assembled state. Alternatively, one or each slot insulation can be made entirely from felt, fur, textile or a sponge, i.e. a sponge-like material, such as a material for kitchen sponges. In the sense of the invention, a sponge is meant to be a plastic material, in particular made of polyurethane or melamine resin foam, with a porous and / or absorbent structure.This results in the advantage that the slot insulation can absorb the impregnation material in the liquid state and store it until it hardens, and in the hardened state can encompass, enclose or firmly enclose it.

[0014] In a further embodiment, it is provided that the surface insulating material has a swellable coating on at least one side of a respective slot insulation facing a respective stator slot and / or the at least one conductor element arranged therein, which coating is designed to swell upon absorption of the liquid impregnation material and thereby increase its volume and to at least partially retain this increased volume in the cured state of the absorbed impregnation material. In other words, the slot insulation should swell upon absorption or absorption of the still liquid impregnation material, i.e., increase its volume and thereby absorb the liquid impregnation material in the increased volume. After the impregnation material has hardened, the slot insulation should retain its increased volume.This results in the advantage that the at least one cavity, i.e. the one or more cavities that can be arranged between a slot insulation and the respective at least one conductor element or between the conductor elements, are at least partially filled by the swollen slot insulation, in particular by the swollen coating, thereby providing mechanical strength and / or electrical insulation to the laminated core. Part of the cavity or cavities that are not completely filled by the swollen coating can be filled by the impregnation material introduced in the liquid state in the cured state. By coating is meant here that, for example, the surface insulating material is a paper that is provided or coated with the coating on at least one side.The coating can be a textile, a sponge, felt, or fur, for example, glued to one side of the paper. The coating itself can be designed as a surface insulation material. Alternatively, the slot insulation can also be made entirely of one of the aforementioned materials.

[0015] In a further embodiment, the wall of the laminated core is rotationally symmetrical about an imaginary central axis extending along the axial direction through the receiving space. In other words, the wall of the laminated core can have the shape of a hollow cylinder that is open at an imaginary base and cover surface so that a rotor can be guided or pushed into the receiving space. The imaginary central axis can be an axis of rotation of the accommodated rotor. This results in the advantage that an electric motor that comprises the stator and additionally a rotor enclosed by the stator or accommodated in the receiving space can be operated particularly efficiently if the receiving space is circular.

[0016] A second aspect of the invention relates to a method for producing a stator, in particular according to the first aspect of the invention. Advantages and advantageous developments or refinements of the first aspect of the invention are to be regarded as advantages and advantageous developments of the second aspect of the invention, and vice versa.

[0017] The method is characterized by the following method steps: lining the stator slots with a slot insulation made at least partially from a surface insulating material with an absorbent surface; arranging at least one conductor element in each stator slot; introducing liquid and curable impregnation material into each stator slot; at least partially absorbing the liquid impregnation material in each stator slot by the slot insulations arranged in the respective stator slots and curing the impregnation material introduced into the stator slots and at least partially absorbed by the respective slot insulations.

[0018] In other words, after arranging or inserting the respective conductor elements into the respective stator slots, impregnating material in a liquid state is to be introduced into the stator slots, where it is to be held at least partially by the respective slot insulation, wherein a part of the liquid impregnating material is held by a capillary effect in the cavities or the cavity between the one or more conductor elements and the respective slot insulation as well as between the conductor elements until the impregnating material hardens.

[0019] A third aspect of the invention relates to an electric motor with a stator, in particular according to the first and second aspects of the invention. Advantages and advantageous developments or refinements of the first and second aspects of the invention are to be regarded as advantages and advantageous developments of the third aspect of the invention, and vice versa.

[0020] A fourth aspect of the invention relates to a motor vehicle having an electric motor with a stator, in particular according to the first, second, and third aspects of the invention. Advantages and advantageous developments or refinements of the first, second, and third aspects of the invention are to be regarded as advantages and advantageous developments of the fourth aspect of the invention, and vice versa.

[0021] Also disclosed is a laminated core for a stator according to the first, second, third, and fourth aspects of the invention. Advantages and advantageous developments or refinements of the first, second, third, and fourth aspects of the invention are to be regarded as advantages and advantageous developments of the disclosed laminated core, and vice versa.

[0022] The laminated core has a wall which delimits a receiving space designed to receive a rotor in a circumferential direction, in which wall a plurality of stator slots are arranged which are distributed in the circumferential direction and each extend along an axial direction of the stator and in each of which at least one conductor element can be arranged, and a slot insulation is arranged on a respective slot wall which at least partially delimits the respective stator slot, wherein the slot insulations each arranged in a respective stator slot are designed in such a way that liquid impregnation material can be absorbed through them before it hardens and are each arranged in the stator slots in such a way that the hardened impregnation material can penetrate the slot insulation at least in some regions and a distribution of the impregnation material can be limited to within the stator slot.Further features of the invention emerge from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures, can be used not only in the respective specified combination, but also in other combinations or on their own.

[0023] The invention will now be explained in more detail using preferred embodiments and with reference to the drawings. They show:

[0024] Fig. 1 is a schematic perspective view of a stator with

[0025] plug-in coil winding;

[0026] Fig. 2 is a schematic sectional view of a slotted stator slot with

[0027] Conductor elements and slot insulation before applying liquid impregnation material

[0028] Fig. 3 is a schematic sectional view of a slotted stator slot with

[0029] Conductor elements and slot insulation after the introduction and curing of impregnation material.

[0030] Fig. 1 shows a stator 1 with a plug-in coil winding 2 made of U-shaped plug-in coils. A plug-in coil can have two conductor elements 7, which can also be referred to as legs of a plug-in coil. In U-shaped plug-in coils, the two conductor elements can be connected to one another. In particular, the U-shaped plug-in coils are each made from a single piece of flat copper wire, for example by forming and / or bending processes. The U-shaped plug-in coils can also be referred to as hairpins. The plug-in coils can be made from flat copper wire, which means that the cross-section of a conductor element can have a square or rectangular shape. The U-shaped plug-in coils can be provided with or coated with a current-flow-inhibiting or electrically insulating coating or varnish. The plug-in coil winding can be inserted into stator slots 6, which can be lined with slot insulation 5.The stator slots can extend in an axial direction through a wall of the laminated core 4. The stator slots 6 can each have a slot arranged facing a receiving space for a rotor. On a side opposite the side having a winding overhang 3, the individual conductor elements 7 can be welded to one another after penetrating the respective stator slots 6 according to a wiring diagram, for example, by a laser welding process. The side with the winding overhang 3 refers to the side on which the respective connecting pieces of the conductor elements of the U-shaped plug-in coils are arranged.

[0031] Fig. 2 shows a schematic sectional view of a slotted stator slot 6 with four conductor elements 7 arranged in the stator slot 6. The stator slot can be lined with slot insulation 5 along a slot wall 8 and across an opening in a slot. Cavities 9 can be formed between the slot insulation 5 and the conductor elements 7 and / or between the conductor elements 7. Fig. 2 shows a cross-section of the stator slot 6 before the curable impregnation material is introduced in a liquid state. The slot insulation 5 can, for example, have paper as surface insulation that is coated on both sides with an absorbent felt. The felt can be attached to the paper, for example, by gluing or adhesive bonding. The slot insulation 5 can be arranged over the entire length of each stator slot in the manner shown in Fig. 2, i.e., for example, along the slot wall and across the opening of the slot (see Fig. 1).In Fig. 2, the conductor elements 7 may have a rectangular cross-section.

[0032] Fig. 3 shows a schematic sectional view of a slotted stator slot 6 with four conductor elements 7 and a slot insulation 5 after the introduction and curing of impregnation material. In this exemplary embodiment, epoxy resin and / or polyester resin can be used as the impregnation material. As shown in Fig. 3, the slot insulation 5 can be swollen after the impregnation material has cured, i.e. the volume of the slot insulation 5 can be increased, particularly into the stator slot. For this purpose, the slot insulation 5 can be made of a surface insulating material such as paper, which can be coated on at least one side facing the stator slot and / or the conductor elements 7 with, for example, a sponge layer, for example made of polyurethane or melamine resin foam, for example by gluing the sponge layer to the paper. Alternatively, the slot insulation 5 can be made only of felt or a sponge layer.The cavities 9 can be filled with cured impregnation material 10 after the impregnation material has hardened. In liquid form, the impregnation material can be held in the cavities 9 by a capillary effect until it hardens. The impregnation material can be introduced into the stator slots 6 in a liquid state, for example, by a trickle impregnation process and / or by a dip impregnation process. As shown in Fig. 3, after the impregnation material has hardened, the conductor elements 7 can be mechanically fixed by the swollen slot insulation 5 in conjunction with the cavities 9 filled with cured impregnation material 10. In other words, the conductor elements 7 can no longer move in each stator slot 6 after the impregnation material has hardened. In Fig.3 it can be seen that the swollen slot insulation 5 can partially protrude into the cavities 9 or can expand into the cavities 9 by swelling.

[0033] A particularly preferred embodiment is described below.

[0034] The following can occur with a GEN5 stator protection (GEN5: 5th generation): Damage to the insulation, which can also be referred to as varnish or coating, preferably made of polyamide-imide, of the winding heads 2 or the plug-in coils in the area of ​​the winding head 3 of stators 1 during continuous temperature cycling at locations with excess impregnation resin, which can also be referred to as impregnation material. Due to thermomechanical stresses at interfaces between a copper enamel wire, i.e., a copper wire coated with varnish, in particular a copper flat wire, and an undesired impregnation resin coating, a pre-aged PAI coating (PAI: polyamide-imide) of the wire can crack and detach from a wire, which can also be referred to as a copper flat wire.

[0035] For the assembly of a hairpin winding, which can also be referred to as a plug-in coil winding 2, a joining clearance, which can also be referred to as play, is required between the wires and the slot, which can also be referred to as the stator slot 6. Due to the shape and position tolerances of the wires, this leads to irregular spacing between the wires and the stator slot 6, so that the play can concentrate locally in some places and lead to larger cavities 9. The stator slots 6 are usually lined with a thin, solid surface insulating material, which can be enclosed by a slot insulation 5, which has a constant thickness and cannot fill the joining clearance or the cavities.When trickle-impregnating the active part of a winding, which can also be referred to as a plug-in coil winding 2, the capillary action is no longer sufficient, so that larger cavities 9 are not filled and a portion of the impregnating resin, which may still be in a liquid state, flows out of the slots and onto the winding heads 3. The active part can be referred to as the part of a plug-in coil winding that is arranged in the stator slots 6. The play between the wires and the stator slot is filled by a soft, absorbent layer of slot insulation. This enables the winding to be installed despite the small play and improves the capillary action, whereby less resin or impregnating material flows out of the slot in a liquid state.

[0036] For this purpose, the respective slot insulation 5 can comprise a surface insulating material with a soft, absorbent surface (for example, sponge, felt, fur, and / or textile). This can result in the advantage that cavities 9 are partially filled without hindering the joining process, i.e., the introduction of the respective conductor elements 7 into a respective stator slot 6. As a further advantage, this slot insulation 5 can easily absorb the impregnation resin. Additionally or alternatively, the surface insulating material can be provided or coated with a swelling coating, for example, made of a compressed sponge, felt, fur, and / or textile. This can result in the advantage that the coating is solid and does not get in the way when the hairpins are joined, and / or the coating swells during impregnation and fills the cavities 9.

[0037] List of reference symbols

[0038] stator

[0039] Plug-in coil winding

[0040] Wrap heads

[0041] Sheet metal package

[0042] Slot insulation

[0043] Stator slot

[0044] Ladder element

[0045] Groove wall

[0046] Cavity cured impregnation material

Claims

Patent claims 1. Stator (1) with plug-in coil winding (2) for an electric motor for a motor vehicle, comprising a plurality of plug-in coils, each having at least one conductor element (7) through which electric current can flow, and comprising a laminated core (4) which forms a wall delimiting a receiving space designed to accommodate a rotor in a circumferential direction, and in which wall a plurality of stator slots (6) are arranged distributed in the circumferential direction, each extending along an axial direction of the stator (1) and in each of which at least one conductor element (7) is arranged, and a slot insulation (5) is arranged on a respective slot wall (8) at least partially delimiting the respective stator slot (6), and at least one hollow space (9) is formed between a respective slot insulation (5) and the respective at least one conductor element (7), which hollow space is at least partially filled with a cured impregnation material (10).characterized in that the slot insulation (5) arranged in a respective stator slot (6) is designed in such a way that liquid impregnation material can be absorbed by it before it hardens and is arranged in the respective stator slot (6) in such a way that the slot insulation (5) is penetrated at least in regions by the hardened impregnation material (10) and a distribution of the impregnation material is limited to within the stator slot (6).

2. Stator (1) according to claim 1, characterized in that the slot insulations (5) are at least partially made of a surface insulating material with an absorbent surface, which is designed to absorb the impregnating material in a liquid state before the impregnating material hardens by suction and to retain it for up to to keep it stored after curing and to at least partially enclose the impregnating material in a cured state after curing.

3. Stator (1) according to claim 2, characterized in that the surface insulating material has a swellable coating on at least one side of a respective slot insulation (5) facing a respective stator slot (6) and / or the at least one conductor element (7) arranged therein, which coating is designed to swell when the liquid impregnating material is absorbed and thereby increase its volume and to at least partially retain this increased volume in the cured state of the absorbed impregnating material.

4. Stator (1) according to one of the preceding claims, characterized in that the wall of the laminated core (4) is rotationally symmetrical about an imaginary central axis extending along the axial direction through the receiving space.

5. A method for producing a stator (1) according to one of claims 1 to 4, characterized by the following method steps: • lining the stator slots (6) with a slot insulation (5) made at least partially from a surface insulating material with an absorbent surface; • Arranging at least one conductor element (7) in each stator slot (6); • Introducing liquid and hardenable impregnation material into each stator slot (6); • At least partial absorption of the liquid impregnation material in each stator slot (6) by the slot insulations (5) arranged in the stator slots (6); and • Hardening of the impregnation material introduced into the stator slots (6) and at least partially absorbed by the respective slot insulations (5).

6. Electric motor with a stator (1) according to one of claims 1 to 4.

7. Motor vehicle with at least one electric motor according to claim 6.

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