Stator and method for producing a stator

Abstract

The invention relates to a stator (1) of an electric machine (2), in particular of an electric machine for a drive train (3) of a motor vehicle (4), comprising a hollow cylindrical stator body (6) which is formed from a plurality of stator laminations (5) in groups and has a plurality of stator slots (7), the stator body (6) has a stator slot (7) which extends axially through the stator body (6) and has a cross-section with a U-shaped profile having two substantially parallel side walls (8) and a slot base (9) and a slot opening (10) which is arranged radially opposite the slot base (9), a plurality of electrical conductors (11) having a substantially rectangular conductor cross-section are arranged radially above one another in order to form a stator winding (12), the slot opening (10) having a circumferential width (13) that is smaller than a circumferential width (14) of the electrical conductor (11) radially closest to the slot opening (10), such that the electrical conductors (11) are arranged in the respective stator slots (7) in a radially limited manner, the electrical conductor (11) radially closest to the slot opening (10) is plastically deformed in the circumferential direction by pressure fitting in the radial direction towards the slot base (9).

Description

Technical Field

[0001] The invention relates to a stator for an electric machine, in particular for a drive train of a motor vehicle, the stator comprising a hollow cylindrical stator body formed from a plurality of grouped stator laminations and having a plurality of stator slots extending axially through the stator body and having a cross section with a U-shaped profile having two substantially parallel side walls and a slot base and a slot opening arranged radially opposite the slot base, wherein in each stator slot a plurality of electrical conductors with a substantially rectangular conductor cross section are arranged radially above one another to form a stator winding, wherein the slot opening has a circumferential width that is smaller than the circumferential width of the electrical conductor radially closest to the slot opening, so that the electrical conductors are arranged radially confined in the respective stator slot. The invention also relates to a method for producing the stator. Background Art

[0002] Electric motors are increasingly used to drive motor vehicles in order to create an alternative to fossil fuel-intensive internal combustion engines. Considerable efforts have been made to improve the suitability of electric drives for everyday use and also to be able to provide users with the driving comfort they are accustomed to.

[0003] A detailed description of electric drives can be found in the article by Erik Schneider, Frank Fickl, Bernd Cebulski and Jens Liebold in the German automobile magazine ATZ, issue 63, 05 / 20 6, pages 360 to 365, entitled: Hochintegrativ und Flexibel Elektrische Antriebseinheit für E-Fahrzeuge [Highly Integrative and Flexible Electric Drive Unit for E-Vehicles]. The article describes a drive unit for a vehicle axle, which comprises an electric motor arranged coaxially with a bevel gear differential. Such a drive unit is also known as an electric axle.

[0004] In addition to purely electrically operated drive trains, hybrid drive trains are also known. Such drive trains of hybrid vehicles generally comprise a combination of an internal combustion engine and an electric motor and enable, for example, a purely electric operating mode in urban areas while allowing both sufficient range and usability, in particular also when driving off-road. In addition, in certain operating situations, it is also possible to use both the internal combustion engine and the electric motor simultaneously for driving purposes.

[0005] In addition to electric vehicle applications, electric machines are also used, for example, as electric motors for automation or as industrial motors. In particular, various types as well as different numbers and requirements of industrial motors can be obtained. One way to master this diversity is to use common geometries, such as sheet metal segments, in order to then distinguish the products into types with their properties via the interconnection of the individual coils.

[0006] Regarding the development of electric machines, in particular regarding the above-mentioned hybrid and fully electric vehicles or electric machines for wheel drives, various winding techniques for the stator of an electric machine are known.

[0007] An electric machine having a hollow cylindrical stator, i.e., designed as an inner rotor machine and configured to be used as a traction drive in a motor vehicle, typically has a stator winding with a rectangular cross-section in order to achieve a high power density. Thus, the stator winding of an electric machine intended to drive a motor vehicle is usually designed as an axial winding.

[0008] The structure of a stator with an axial winding is a stator design in which winding pads are used to form a specific phase winding. To form a distributed winding, the individual winding wires or partial pads are woven together, for example, by a winding or layering process and inserted into the stator slots. The axial winding has a plurality of phases, usually three phases, where for each phase at least two individual wires or windings are typically provided. In each case, one winding is formed by a first winding pad and a second winding pad, where in a preferred embodiment, one winding pad carries current in a clockwise direction and the other winding pad carries current in a counterclockwise direction. The first winding pad extends, for example, counterclockwise from an axially extending phase input pin to an axially extending interconnection pin, or the first winding pad alternatively has said pins. Via the interconnection pin, the first winding pad is connected to the interconnection pin of the second winding pad by means of an interconnection element, which also extends axially and then extends clockwise to an axially extending phase output pin. This means that each phase-specific winding is formed by two winding pads connected in series and is thus a separate winding, which is connected via an interconnection element. In the case of three phases and two or one individual winding for each phase, six or three windings are thus provided. The phase output pins are in turn connected to each other via a common star switching element. The number of windings or wires is at least equal to the number of phases or a multiple of the number of phases. SUMMARY OF THE INVENTION

[0009] The object of the present invention is to provide a stator optimized in terms of manufacturing and assembly costs. The object of the present invention also lies in implementing a simplified method for producing a stator winding.

[0010] This object is achieved by a stator of an electric machine, in particular of a drive train for a motor vehicle, the stator comprising a hollow cylindrical stator body which is formed from a plurality of groups of stator laminations and has a plurality of stator slots which extend axially through the stator body and have a cross-section with a U-shaped profile having two substantially parallel side walls as well as a slot base and a slot opening arranged radially opposite the slot base, wherein in the stator slots a plurality of electrical conductors with a substantially rectangular conductor cross-section are arranged radially above one another to form a stator winding, wherein the slot opening has a circumferential width which is smaller than the circumferential width of the electrical conductor radially closest to the slot opening, such that the electrical conductors are arranged radially restricted in the respective stator slots, and wherein the electrical conductor radially closest to the slot opening is plastically deformed in the circumferential direction by a press-fit in the radial direction towards the slot base.

[0011] This has the advantage that no additional slot locking means, such as slot locking wedges, are required to arrange the electrical conductors restricted in the stator slots. For this purpose, the rectangular wire geometry of the electrical conductors in the stator slots is formed by press-fit without cutting in order to form a width which is greater than the width of the slot opening.

[0012] For example, the stator winding can initially be fixed in the stator slots of the stator body by self-locking. Compared to a complete winding compression, the degree of deformation required for the electrical conductors is very small, such that there is only a very low risk of insulation damage. The fill factor of the stator winding in the stator slots can also be increased. The fact that the entire stator winding can be formed simultaneously in the stator slots of the stator means that the applied pressure can be better distributed in the stator or cancelled out with one another, such that the risk of local deformation is also low.

[0013] First, the individual elements of the subject matter claimed in the present invention are explained in the order in which these elements are mentioned in the claims, and thereafter a particularly preferred embodiment of the subject matter of the present invention is described.

[0014] The stator according to the invention is intended for use in an electric machine. The electric machine serves to convert electrical energy into mechanical energy and / or to convert mechanical energy into electrical energy, and the electric machine generally comprises a stationary part, known as the stator, yoke or armature, and a part, known as the rotor or runner, which is arranged in a movable manner, in particular rotatably, relative to the stationary part. In particular, the electric machine is dimensioned such that vehicle speeds of more than 50 km / h, preferably more than 80 km / h, and in particular more than 100 km / h can be achieved. The electric motor particularly preferably has an output of more than 10 kW, in particular more than 30 kW, preferably more than 50 kW and in particular more than 70 kW. Furthermore, it is preferred that the electric machine provides a speed of more than 5000 rpm, particularly preferably more than 10000 rpm, very particularly preferably more than 12500 rpm. In the case of an external rotor, such as a wheel hub drive, the corresponding electric machine can provide a speed of up to 1500 rpm.

[0015] In particular, the stator can be supplied by power electronics. The power electronics is preferably a combination of various components for controlling and regulating the current at the stator, which various components preferably include the peripheral components required for this purpose, such as cooling elements or power supply units. In particular, the power electronics comprises one or more power electronic components which are arranged to control or regulate the current. These power electronic components are preferably one or more power switches, such as power transistors. Particularly preferably, the power electronics has more than two independent phases or current paths, and particularly preferably has three independent phases or current paths, each independent phase or current path having at least one independent power electronic component. The power electronics is preferably designed to control or regulate the power per phase, where the peak power, preferably the continuous power, is at least 10 W, preferably at least 100 W, particularly preferably at least 1000 W per phase. The power electronics is preferably connected to the stator winding of the stator via HV terminals (HV = high voltage).

[0016] For the purposes of the present application, a motor vehicle is a land vehicle that is moved by machine power and is not restricted to a railway track. Motor vehicles can be selected, for example, from the group consisting of: passenger cars, trucks, scooters, light motor vehicles, motorcycles, buses / coaches or tractors.

[0017] The stator according to the invention can preferably be configured for a radial flux type machine. The stator of a radial flux type machine typically has a cylindrical or tub-shaped annular structure and generally includes a stator body formed of electrical laminations, which are electrically insulated from one another and are constructed in a layered manner and encapsulated to form a laminated core. With this structure, the eddy currents in the stator caused by the stator field remain low. Stator slots are embedded in the electrical laminations extending parallel to the rotor axis in a circumferentially distributed manner, and the stator slots receive the stator winding or parts of the stator winding. Depending on the construction towards the surface, the slots can be closed with closing elements, such as closing wedges or covers, etc., to prevent the stator winding from separating.

[0018] The stator body is preferably designed as one-piece. The one-piece stator body is characterized by the fact that, when viewed in the circumferential direction, the entire stator body is formed as one piece. The stator body is generally formed by a plurality of stacked piezoelectric sheets (electrical laminations), where each electrical lamination in the electrical laminations closes to form a circular ring-shaped piece. The individual laminations can be held together in the stator body, for example, by adhesive bonding, welding or screwing.

[0019] The stator teeth of the stator are preferably formed in the stator body. The stator teeth are components of the stator body, and these stator teeth are designed as circumferentially spaced tooth-shaped parts that point radially inwards (inner rotor) or radially outwards (outer rotor) of the stator body, and an air gap for the magnetic field and for the rotational movement of the rotor is formed between the free ends of these stator teeth and the rotor body. The non-magnetic gap existing between the rotor and the stator is called the air gap. For example, in a radial flux type machine, the air gap is a substantially annular gap having a radial width that corresponds to the distance between the rotor body and the stator body.

[0020] The stator winding is embedded in the stator slots of the stator according to the invention. The stator winding includes conductive conductors, which have a longitudinal extent that is much greater than their diameter. The stator winding can generally have any cross-sectional shape. A rectangular cross-sectional shape is preferred because these rectangular cross-sectional shapes allow a high packing density and thus achieve a high power density. Particularly preferably, the stator winding is formed of copper. According to the invention, the stator winding is designed as a continuous shaft winding. In addition, the electrical conductors preferably have substantially the same cross-section before being inserted into the stator slots. The electrical conductors can also preferably have an electrical insulation layer.

[0021] Advantageous embodiments of the invention are specified in the dependent claims. The features listed individually in the dependent claims can be combined with one another in a technically meaningful way and can define further embodiments of the invention. In addition, the features indicated in the claims are specified and explained in more detail in the description, where other preferred embodiments of the invention are shown.

[0022] According to an advantageous embodiment of the invention, it can be provided that the stator slots each have a circumferential slot width, wherein the circumferential width of the electrical conductor that is radially closest to the slot opening is smaller than this circumferential slot width. The advantage of this design is that there is still a gap between the slot wall and the electrical conductor at the slot opening, which ensures that the electrical conductor flows into the stator slot and thus ensures sufficient cooling in this area.

[0023] According to a further preferred refinement of the invention, it can also be provided that the electrical conductor that is radially closest to the slot opening has a trough-shaped section on its longitudinal side facing the slot opening, the cross-section of which points in the direction of the slot base, and this trough-shaped section is formed by press-fitting using a convex punch. Thus, a preferred press-fitting of the material in two circumferential directions can be achieved with a relatively low radial compressive force.

[0024] According to an advantageous embodiment of the invention, it can be provided that the defined distance between the pole piece geometry or the air gap and the first electrical conductor is defined by providing a tapered slot geometry and fixing the first conductor at a defined position for press-fitting. This defined distance can both fulfill the function of the necessary air and creepage distances and can be selected such that the losses induced by the rotor magnetic field in the first conductor near the air gap are minimized.

[0025] Furthermore, according to an equally advantageous embodiment of the invention, it can be provided that the electrical conductor has a coating made of an electrically insulating material. The advantage of this design is to provide high dielectric strength and require small gaps and creepage distances. The coating is preferably a PEEK coating.

[0026] In the case of specific requirements for gaps and creepage distances, an advantageous method variant provides an insulating device, such as Nomex insulating paper, that is located on the winding as a surface insulating element and is intended to be press-fitted together with the electrical conductor such that the fixed assembly of the surface insulating element is ensured due to form fit. The form fit can be achieved by clamping on the surface of the slot side or via the designed slot shape of the punch or the resulting slot shape of the conductor. The use of a thinner surface insulating element has advantages in terms of product cost and installation space compared to the commonly used plastic-based solid body used as a slot closing wedge.

[0027] According to another particularly preferred embodiment of the invention, it can be provided that the side walls and the base in each stator slot in the stator slots are in contact with an insulating device. Furthermore, the invention can be further improved in that the insulating device is insulating paper. The advantage of this design is that the insulation between the electrical conductor and the stator body can be further improved.

[0028] The object of the invention is also achieved by a method for producing a stator of an electric machine, in particular for a powertrain of a motor vehicle, the method comprising the following steps:

[0029] · Providing a hollow cylindrical stator body, which is formed by a plurality of stacked stator laminations and has a plurality of stator slots, the stator slots extending axially through the stator body and having a cross-section with a U-shaped profile, the U-shaped profile having two substantially parallel side walls as well as a slot base and a slot opening arranged radially opposite the slot base,

[0030] · Providing a plurality of electrical conductors having a substantially rectangular conductor cross-section for forming a stator winding,

[0031] · Inserting the electrical conductors from the radial direction through each of the slot openings in the direction of the slot base into the stator slots, such that in each case a plurality of electrical conductors are arranged radially above one another in the stator slots, wherein the slot opening has a circumferential width that is greater than the circumferential width of the electrical conductor,

[0032] · Press-fitting the electrical conductor that is radially closest to the slot opening by means of a punch, the punch engaging through the slot opening in the radial direction towards the slot base and plastically deforming the electrical conductor that is radially closest to the slot opening in the circumferential direction, such that the circumferential width of the electrical conductor that is radially closest to the slot opening is greater than the circumferential width of the slot opening and the electrical conductor is arranged radially restricted in the respective stator slot.

[0033] The output wire of the electrical conductor can be a classic rectangular wire, preferably a rectangular wire with a PEEK coating, in order to generate a high dielectric strength and require minimal clearances and creepage distances. In the classic spreading process for a flat wire type shaft winding arranged in a stator slot, the radial connection process does not terminate when the electrical conductor reaches its final position in the stator slot, but rather the forming process of the electrical conductor begins after the insertion process. The wire cross-section of the electrical conductor that is radially closest to the slot opening is thereby changed in the slot opening such that the wire width of the electrical conductor becomes greater than the opening of the stator slot, but preferably has not yet reached the entire slot width. After forming, the assembly punch retracts radially from the stator slot.

[0034] It can also be advantageous to further improve the invention such that the cross-section of the punch has a convex profile facing the electrical conductor. The advantage that can be achieved here is that a preferred material offset can be achieved on both sides of the electrical conductor in the circumferential direction, which reduces the radial compressive force required for press-fitting.

[0035] According to another preferred embodiment of the object of the invention, it can be provided that each of the stator slots has a circumferential slot width, wherein the press-fitting is set such that after the plastic deformation has been carried out, the circumferential width of the electrical conductor that is radially closest to the slot opening is less than the circumferential slot width.

[0036] This allows gaps to be maintained on both sides of the electrical conductor facing the slot walls. For example, cooling fluid can flow through the gaps, which can contribute to particularly efficient heat dissipation from these areas. This can also reduce the risk of mechanical damage to the insulating medium.

[0037] Finally, the invention can also be advantageously implemented such that before inserting the electrical conductor, insulating means are arranged on the side walls and the base of the stator slots, which further improves the electrical insulation of the electrical conductor relative to the stator body. Description of the Drawings

[0038] The invention will now be described in more detail with reference to the drawings without limiting the general concept of the invention.

[0039] In the drawings:

[0040] Figure 1 A motor vehicle having an electric drive train is shown schematically in a block diagram,

[0041] Figure 2 A motor is shown schematically in a cross-sectional view,

[0042] Figure 3 A detailed view of a stator slot is shown in a cross-sectional view,

[0043] Figure 4 Four consecutive assembly states during the insertion of the electrical conductor into the stator slot are shown in cross-sectional views in each case,

[0044] Figure 5 Four consecutive assembly states during the press-fitting of the electrical conductor into the stator slot are shown in cross-sectional views in each case,

[0045] Figure 6 Three consecutive assembly states during the press-fitting of the electrical conductor using a second embodiment of the punch are shown in cross-sectional views. Detailed Description

[0046] The invention will be described in more detail with reference to the stator 1 of the motor 2 of the drive train 3 for a motor vehicle 4, as also Figure 1 sketched schematically in.

[0047] The stator 1 consists of a plurality of groups of stator laminations 5, which form a hollow cylindrical stator body 6. A rotor 16 is mounted inside the stator body 6 such that the rotor can rotate coaxially with the stator body. In the illustrated embodiment variant, the motor 2 is designed as an internal rotor.

[0048] The stator body 6 is provided with a plurality of stator slots 7 that extend axially through the stator body 6 and are arranged equidistantly around the circumference. The plurality of stator slots have a cross-section with a U-shaped profile, which has two substantially parallel side walls 8, a slot base 9, and a slot opening 10 arranged radially opposite to the slot base 9, which can be easily understood from Figure 2 It can be easily understood from the figure. The stator teeth 18 extend radially inwards from the circular annular stator yoke such that the stator slots 7 are defined between the stator teeth 18.

[0049] In each stator slot 7, a plurality of electrical conductors 11 having a substantially rectangular conductor cross-section are arranged radially above one another to form a stator winding 12. The slot opening 10 has a circumferential width 13 that is smaller than the circumferential width 14 of the electrical conductor 11 that is radially closest to the slot opening 10, such that the electrical conductors 11 are arranged radially restricted in the respective stator slots 7, as shown in Figure 3 It is shown in the figure.

[0050] The electrical conductor 11 that is radially closest to the slot opening 10 is plastically deformed in the circumferential direction by press-fitting in the radial direction towards the slot base 9. Figure 3 It is also shown that each stator slot 7 has a circumferential slot width 19, wherein the circumferential width 14 of the electrical conductor 11 that is radially closest to the slot opening 10 is smaller than the circumferential slot width 19. In the illustrated embodiment, the electrical conductors 11 have a coating made of an electrically insulating material. Figure 3 It is also shown that in each of the stator slots 7, the side walls 8 and the slot base 9 are in contact with an insulating device 17. In the illustrated embodiment variant, the insulating device 17 is insulating paper.

[0051] Now referring to Figures 4 to 6 More specifically, an explanation will be given of a possible method for producing a stator known from Figures 2 to 3 It is known.

[0052] First, a hollow cylindrical stator body 6 formed by a plurality of groups of stator laminations 5 and having a plurality of stator slots 7 is provided. The stator slots extend axially through the stator body 6 and have a cross-section with a U-shaped profile, which has two substantially parallel side walls 8, a slot base 9, and a slot opening 10 arranged radially opposite to the slot base 9. In addition, a plurality of electrical conductors 11 having a substantially rectangular conductor cross-section are provided to form a stator winding 12.

[0053] Before the electrical conductors 11 are inserted, an insulating device 17 is provided on the side walls 8 and the slot base 9 of the stator slots 7. Then, the electrical conductors 11 are inserted into the stator slots 7 from the radial direction through each of the slot openings 10 in the direction of the slot base 9, such that in each case, a plurality of electrical conductors 11 are arranged radially above one another in the stator slots 7, wherein the slot opening 10 has a circumferential width 13 that is greater than the circumferential width 14 of the electrical conductors 11. These production states can be seen inFigure 3 as seen in FIGS. a to d. When the conductor 11 is inserted, the conductor and the punch 15 are guided radially outside the stator slot 7 through the tool 21. Then the punch 15 presses the electrical conductor 11 radially from the inside to the outside into the stator slot 7.

[0054] After the electrical conductor 11 is fully positioned in the stator slot 7, then the conductor 11 that is radially closest to the slot opening 10 is press-fitted by means of the punch 15. The punch engages through the slot opening 10 in the radial direction towards the slot base 9 and plastically deforms the conductor 11 that is radially closest to the slot opening 10 in the circumferential direction such that the circumferential width 14 of the conductor 11 that is radially closest to the slot opening 10 is greater than the circumferential width 13 of the slot opening 10, and the conductor 11 is arranged radially restricted in the respective stator slot 7. This can be seen in Figure 5 FIGS. e to f.

[0055] After the press-fitting, the punch 15 is radially pulled out of the stator slot 7 and the tool 21 is removed, resulting in Figure 4 the assembled state shown in FIG. g. Subsequently, the insulating device 17 can be folded inwards into the stator slot 7 at the end facing the slot opening 10, as can be seen in Figure 4 FIG. h.

[0056] Figure 6 An embodiment of the punch 15 is shown in which the cross-section of the punch 15 has a convex profile facing the conductor 11. Thereby, a grooved section 20 with a cross-section pointing in the direction of the slot base 9 can be pressed on the longitudinal side 22 facing the slot opening 10 of the conductor 11 that is radially closest to the slot opening 10.

[0057] Figures 4 to 5 It is also shown that the stator slots 7 each have a circumferential slot width 19, wherein the press-fitting is set such that after the plastic deformation has been carried out, the circumferential width 14 of the conductor 11 that is radially closest to the slot opening 10 is less than the circumferential slot width 19.

[0058] In Figures 2 to 6 the embodiment shown, an unequal number of conductors 11 are arranged in the stator slots 7. It should be understood that, for example, if the stator winding 12 is designed as an axial winding, the number of conductors 11 in the stator slots 7 can also be uniform.

[0059] The present invention is not limited to the embodiments shown in the drawings. The above description should therefore not be considered restrictive but rather illustrative. The appended claims should be understood to mean that the stated features are present in at least one embodiment of the invention. This does not exclude the presence of other features. Where the claims and the above description define a "first" feature and a "second" feature, such designations are used to distinguish between two features of the same type and do not define a priority order.

[0060] List of reference numerals

[0061] 1 Stator

[0062] 2 Electric machine

[0063] 3 Powertrain

[0064] 4 Motor vehicle

[0065] 5 Stator sheet

[0066] 6 Stator body

[0067] 7 Stator slot

[0068] 8 Side wall

[0069] 9 Slot base

[0070] 10 Slot opening

[0071] 11 Electric conductor

[0072] 12 Stator winding

[0073] 13 Width

[0074] 14 Width

[0075] 15 Punch

[0076] 16 Rotor

[0077] 17 Insulating device

[0078] 18 Stator tooth

[0079] 19 Slot width

[0080] 20 Grooved section

[0081] 21 Tool

[0082] 22 Longitudinal side.

Claims

1. A stator (1) of an electric machine (2), in particular of an electric machine for a powertrain (3) of a motor vehicle (4), said stator comprising: a hollow cylindrical stator body (6) formed by a plurality of groups of stator laminations (5) and having a plurality of stator slots (7) which extend axially through the stator body (6) and have a cross-section with a U-shaped profile having two substantially parallel side walls (8) and a slot base (9) and a slot opening (10) arranged radially opposite the slot base (9), wherein, in each stator slot (7), a plurality of electrical conductors (11) having a substantially rectangular conductor cross-section are arranged radially above one another to form a stator winding (12), wherein the slot opening (10) has a circumferential width (13) which is smaller than the circumferential width (14) of the electrical conductor (11) which is radially closest to the slot opening (10), such that the electrical conductor (11) is arranged radially confined in the respective stator slot (7), characterized in that the electrical conductor (11) which is radially closest to the slot opening (10) is plastically deformed in the circumferential direction by means of a press fit in the radial direction towards the slot base (9).

2. The stator (1) according to claim 1, characterized in that each of the stator slots (7) has a circumferential slot width (19), wherein the circumferential width (14) of the electrical conductor (11) which is radially closest to the slot opening (10) is smaller than the circumferential slot width (19).

3. The stator (1) according to claim 1 or 2, characterized in that the electrical conductor (11) which is radially closest to the slot opening (10) has a grooved section (20) on the longitudinal side (22) of the conductor facing the slot opening (10), the cross-section of which points in the direction of the slot base (9).

4. The stator (1) according to any one of the preceding claims, characterized in that the electrical conductor (11) has a coating made of an electrically insulating material.

5. The stator (1) according to any one of the preceding claims, characterized in that in each of the stator slots (7), an insulating means (17) is in contact with the side wall (8) and the slot base (9).

6. The stator (1) according to claim 5, characterized in that the insulating means (17) is insulating paper.

7. A method for producing a stator (1) of an electric machine (2), in particular of an electric machine for a powertrain (3) of a motor vehicle (4), the method comprising the following steps: providing a hollow cylindrical stator body (6) formed by a plurality of groups of stator laminations (5) and having a plurality of stator slots (7) which extend axially through the stator body (6) and have a cross-section with a U-shaped profile having two substantially parallel side walls (8) and a slot base (9) and a slot opening (10) arranged radially opposite the slot base (9), providing a plurality of electrical conductors (11) having a substantially rectangular conductor cross-section to form a stator winding (12), Insert the electrical conductors (11) from the radial direction through each of the slot openings (10) in the direction of the slot base (9) into the stator slots (7) such that, in each case, a plurality of electrical conductors (11) are arranged radially above one another in the stator slots (7). wherein the slot openings (10) have a circumferential width (13) that is greater than the circumferential width (14) of the electrical conductors (11). Press-fit the electrical conductor (11) that is radially closest to the slot opening (10) by means of a punch (15) that engages through the slot opening (10) in the radial direction towards the slot base (9) and plastically deforms the electrical conductor (11) that is radially closest to the slot opening (10) in the circumferential direction such that the circumferential width (14) of the electrical conductor (11) that is radially closest to the slot opening (10) is greater than the circumferential width (13) of the slot opening (10), and the electrical conductor (11) is arranged radially confined in the respective stator slot (7).

8. The method according to claim 7, characterized in that the punch (15) has a convex cross-sectional profile facing the electrical conductor (11).

9. The method according to claim 7 or 8, characterized in that the stator slots (7) each have a circumferential slot width (19), wherein the press-fit is set such that, after the plastic deformation has been carried out, the circumferential width (14) of the electrical conductor (11) that is radially closest to the slot opening (10) is less than the circumferential slot width (19).

10. The method according to any one of claims 7 to 9, characterized in that before inserting the electrical conductors (11), an insulating device (17) is provided on the side walls (8) and the slot base (9) of the stator slots (7).

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