Stator of electric motor having antifriction coating at slot slits

Abstract

The invention relates to a method for producing a stator (2) of an electric motor (1), comprising the following steps:-laminating a laminated core (23) having at least one stator bore (30), axially extending slots (8) and slot slits (12) facing the stator bore (30), the slot slits (12) being formed in the stator bore (30) in a circumferential direction, the slot (8) is formed by two directly adjacent tooth shafts (4), a section of the corresponding tooth tip (6), a slot slit (12) and a slot base (9), and wherein the slot slit (12) is formed by two opposite ends (7) of the adjacent tooth tip (6) when viewed in the circumferential direction, coating the ends (7) with a slidable, in particular electrically insulating coating (16), drawing a winding (25), in particular a prefabricated winding, in particular a winding of a coil-shaped round wire harness, into the slot (8) via the slot slit (12), and coating onto the end (7) of the tooth tip (6) by means of a centrifugal process or a nozzle, in particular a rotary nozzle, which is moved axially within the stator bore (30) during the coating, therefore, the friction-reducing coating (16) is provided for one slot slit (12) or a plurality of slot slits (12) at the same time.

Description

Technical Field

[0001] The invention relates to a method for producing a stator for an electric motor, a stator produced thereby and an electric motor provided with such a stator, and the use of such an electric motor. Background Art

[0002] The winding system of an electric motor (such as a low-voltage motor, for example) is implemented by means of round wire winding technology. The round wire bundle is wound into a coil shape by means of a wing winding machine and then pulled into the slot of the stator by means of an insert sheet.

[0003] In this case, the stator is an axially stacked, in particular stamped, laminated core having radially arranged slots into which copper wire strands are drawn as coils.

[0004] Radially inwardly, i.e. towards the rotor, so-called slot teeth are located on the stator, which are designed in a T-shape and which lead to a constriction of the adjacent slots located therebetween, i.e. the slot gap. Thus, a so-called slot gap or slot gap is created between two slot teeth, which represents a constriction compared to the cross section of the other slots. The copper winding must be pushed through this constriction when it is pulled in, and the constriction therefore represents a "bottleneck" of the technology.

[0005] From an electromagnetic point of view, it is sensible to have a slot slit with a very small opening (almost zero, but electrically insulating) in the case of the stator slots, however, from a production engineering point of view, any narrowing of the actual slot geometry leads to difficulties in the handling of the windings described above.

[0006] Hitherto, the slot gap has been reduced to such an extent that this is permitted by the resulting increased draw-in forces on the automatic wire inserting machines and the wire enamels.

[0007] Increasing the sliding properties of the wire enamel is one possibility for reducing the pull-in forces, since the wire crossover can thereby slide off more easily and come loose.

[0008] However, there are limits to increasing the sliding capability without impairing the later impregnation properties of the winding (the adhesive adhesion of the potting material to such surfaces is extremely poor).

[0009] This is made possible by alternative wire-insertion techniques (eg needle winding techniques or hand winding) by using smaller slot gaps. However, this leads to increased manufacturing costs for the stator.

[0010] Likewise, reducing the copper filling in the slots is possible, but is not a wise choice due to the demands in view of the increase in motor efficiency. Summary of the invention

[0011] Based on this, the object of the present invention is to provide a method for producing a stator which allows winding of a stator of an electric motor and creates an electric motor with a relatively high efficiency.

[0012] The above object is achieved by a method for manufacturing a stator of an electric motor, the method comprising the following steps:

[0013] a stacked laminated core having at least one stator bore, an axially extending slot and a slot slit directed toward the stator bore, wherein the slot, when viewed in the circumferential direction / cross section, is formed by two directly adjacent tooth shafts, a section of the corresponding tooth crest, the slot slit and the slot bottom, wherein the slot slit, when viewed in the circumferential direction, is formed by two opposite ends of adjacent tooth crests,

[0014] - coating the ends with a slidable, in particular electrically insulating, coating,

[0015] A winding, in particular a prefabricated winding, in particular a winding of a coil-shaped round wire bundle, is pulled into the slot via the slot slit.

[0016] The abovementioned object is also achieved by a stator of an electric motor, the slot slots of which are coated in the manner according to the invention.

[0017] The above-mentioned object is also achieved by an electric motor having a stator according to the invention, wherein the efficiency of the electric motor is at least 95%.

[0018] The abovementioned objects are also achieved by the use of an electric motor according to the invention for a drive, in particular for drives in continuous operation, such as fans, compressors, pumps or the like.

[0019] With regard to the winding being pulled in via the slot slits, the coating of the ends of the tooth tips at the slot slits or in the region of the slot slits provides a protective effect.

[0020] Compared to the prior art, in which the inserting plates of the plate-like tool cover the slot gap during the inserting operation of pulling in the winding, there is in fact a reduction in the slot gap due to the coating, but not to this extent to date.

[0021] The inserting plate, which locally limits the wire bundle of the winding at the slot slit, is designed in this case so that the inserting plate as a side wall is also pushed into the slot gap in order to ensure that the wire is mechanically protected from damage by the slot teeth during insertion. This is necessary because the wire bundle is pulled in almost in the axial direction and the wire bundle is therefore mechanically worn at the edge of the plate (which, like the individual plates, is located perpendicular to the direction of movement).

[0022] During the standard winding insertion process using insert plates, the protective layer of the wire bundle is designed as the side walls of the plate-shaped tool made of 0.3 mm stainless steel, which requires additional tolerances with respect to the slot teeth.

[0023] This problem is solved by the protective side walls of the insert sheet consisting of smooth polished steel, but this also limits the effective slot width by twice the thickness plus the tolerance (typical values ​​in this case are: slot slit: 3.2 mm, narrowing: 2×0.3 mm sheet thickness + 0.4 mm (tolerance and "sheet gap") = 1 mm), that is to say, in this specific case, the taper is about 30%.

[0024] Therefore, in the prior art, the slot gap is reduced specifically as follows. The side wall of the insert plate protruding into the slot gap is 0.3 mm wide on each side, wherein a tolerance of 2×0.1 mm relative to the slot teeth is taken into account. Therefore, a tolerance of 2×0.1 mm relative to the useful teeth can be taken into account. Therefore, the total slot gap loss is recorded here as 0.8 mm+0.2 mm (additional "plate gap"), i.e. 1 mm.

[0025] According to the invention, the protective effect of the sheet-like tool drawn into the sheet body is replaced by a coating applied at the end. The coating can be applied in an additive manner, preferably by spraying, so that the side walls of the sheet-like tool reaching into the slot slit are no longer required at the end.

[0026] According to the invention, a plastic layer is applied to the ends of the slot teeth at least on the end face side before the winding drawing-in method, which plastic layer covers the lamination contour (on the end face side, the individual laminations with lamination edges). It is important here that the applied plastic layer at least covers the lamination edges. A continuous and smooth plastic surface without interruptions is not absolutely necessary, but it is meaningful to reduce sliding wear during the drawing-in method, i.e. to further reduce the drawing-in forces.

[0027] In this case, the coating thickness is a maximum of 50 micrometers. The slot slit is thus reduced to a smaller extent, which simplifies the pulling-in process and in particular reduces the pulling-in force required by the sheet tool. In addition, winding wires with a larger diameter can also be used.

[0028] Therefore, the thickness of the applied coating must be only a few micrometers to a maximum of 50 micrometers in order to statistically ensure that all lamination edges are covered with at least a few micrometers of plastic so that the enameled wire of the winding is not mechanically damaged during the insertion, in particular its insulation is not scratched.

[0029] Typical plastic coatings suitable for this are thermosetting varnishes (e.g. polyetherimide, polyurethane, epoxy resin, polysiloxane, polysilazane, etc.), which can be sprayed on in a thin layer in a diluted manner with the aid of a solvent and harden within a few hours at room temperature by using a two-component material. This time interval can also be shortened by slight heating (e.g. 70° C. for a few hours).

[0030] Another alternative for applying a thin plastic layer is a soluble thermoplastic, such as polyethylene glycol, polyvinyl pyrrolidone or polyvinyl alcohol, which forms a physically dry layer within a short time after the solvent has dried and thus produces a protective film of the above-mentioned thickness. In this case, high molecular weight products are used, which have a molecular weight of at least the subsequent insulation grade of the motor.

[0031] Another possibility to achieve such a layer is to use high melting point waxes and high molecular weight greases, which can then also be sprayed on at high temperatures (eg >250° C.) and provide a protective film by immediate cooling.

[0032] Another possibility is to use high-melting-point thermoplastic hot melt adhesives (e.g. polyamides), which are spun (sprayed) onto the substrate in the form of a spiral through a rotating nozzle, cool and solidify into a layer when it touches the end. A large number of different spray patterns (closed, porous), layer thicknesses and adhesion behaviors are achieved via material temperature, compressed air temperature, pressure, nozzle geometry, etc. The cooled surface then has a sliding ability similar to that of a smooth thermoplastic shell.

[0033] Furthermore, fillers with sliding properties can be added as additives to the aforementioned plastics, which can further improve the sliding wear of the plastic layer and, provided that the additive has a form factor (i.e. in the form of a plate or rod), can bridge the gap between two axially adjacent laminations. In this case, conventional sliding additives such as boron nitride, graphite and polytetrafluoroethylene are possible, which are added to the polymer matrix in a volume percentage of between 1% and 25%.

[0034] As a result of the sprayed-on coating, in principle, regardless of the coating composition, a reduction in the slot size of only 2×50 μm is achieved at most.

[0035] Thus, in the above example, the slot teeth can advantageously be widened to the minimum necessary slot gap determined by the wire used, since the wire bundle can slide over the sprayed-on coating without being damaged at the lamination edges.

[0036] According to the invention, during the process of pulling the winding into the slot through the slot slit, the protection function of the wire harness is achieved by a sliding coating which acts as an insulating layer. It can be significantly thinner and does not require any tolerances for the pull-in sheet extending into the slot slit, without reducing the effective slot slit during the process of pulling the winding using standard tools, whereby the effective slot tooth width can be increased and thus the efficiency of the motor can be increased.

[0037] The method according to the invention for producing a stator for an electric motor therefore now makes it possible to dispense with the pulling in of the side walls of the laminar body, in particular at the slot slits, without having to worry about the enameled wire of the winding being damaged during the pulling in process.

[0038] The coating of the slot slots according to the invention therefore makes correspondingly larger slot teeth, or slot teeth which are wider when viewed in the circumferential direction, possible, which, given a relatively small slot slot width, increases the efficiency of the electric motor by up to one percentage point.

[0039] This is particularly advantageous in the case of drives, in particular drives which are in continuous operation, such as fans, compressors, pumps, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The invention and further advantageous embodiments of the invention are explained in more detail based on a schematically illustrated embodiment, in which:

[0041] Figure 1 shows a schematic longitudinal section of an electric motor,

[0042] Figure 2 shows a schematic cross-sectional view of the stator,

[0043] Figure 3 to Figure 5 shows the pull-in technique according to the prior art,

[0044] Figure 6 and Figure 7 A schematic diagram showing the principle of the spraying method is shown.

[0045] Figures 8 to 10 A schematic diagram showing the principle of the method according to the present invention is shown,

[0046] Fig.11 A partial diagram showing a laminated core,

[0047] Fig.12 A detail view showing a portion of a laminated core,

[0048] Fig.13 A detail view of the slot slit is shown. DETAILED DESCRIPTION

[0049] It should be noted that: just as "axial", "radial", "tangential" etc. refer to the axis 27 used in the respective figures or in the described examples. In other words: the directions axial, radial, tangential always refer to the axis 27 of the rotor 14 and therefore to the corresponding axis of symmetry of the stator 2.

[0050] In this case, "axial" describes a direction parallel to the axis 27, "radial" describes a direction orthogonal to the axis 27, towards it or away from it, and "tangential" is a direction at a constant radial distance from the axis 27 and oriented in a circular manner around the axis 27 with a constant axial position. The expression "in the circumferential direction" is synonymous with "tangential".

[0051] With respect to a surface, eg, a cross-section, the terms "axial", "radial", "tangential" and the like describe the orientation of the surface normal vector, ie, the orientation of the vector perpendicular to the surface in question.

[0052] The expression "coaxial components", such as, for example, rotor 14 and stator 2, is understood here to mean components having the same normal vector, that is, for which the planes defined by the coaxial components are parallel to each other. Furthermore, this expression is also intended to convey that the center points of the coaxial components are located on the same axis of rotation or axis of symmetry. However, the center points may be at different axial positions on this axis and the distance between the mentioned planes is >0 from each other. This expression does not necessarily require that the coaxial components have the same radius.

[0053] The term "complementary" in the context of two "complementary" parts to one another means that the outer shape of the parts is designed so that preferably one part can be arranged completely in its complementary part, so that the inner surface of one part and the outer surface of the other part are in contact ideally without any gaps or over the entire surface area. As a result, in the case of two objects that complement one another, the outer shape of one object is determined by the outer shape of the other object. The term "complementary" can be replaced by the term "inverse".

[0054] For reasons of clarity, in the figures, in some cases in the case of multiple components, not all components shown are generally provided with reference numerals.

[0055] The described embodiments can be combined arbitrarily. Likewise, individual features of the respective embodiments can be combined without departing from the essence of the invention.

[0056] Figure 1The principle view of the electric motor 1 is shown in the form of a longitudinal section. The stator 2 formed by axially stacked laminations 11 has a rotor 14 in a stator bore 30 of the stator. The laminated core 23 is stacked from the individual laminations 11, which stacking is particularly stamping stacking. The stator 2 and the rotor 14 are separated from each other by an air gap 15. A groove 8 is provided on the inner side of the cover surface of the stator bore 30, which groove extends essentially axially and forms a slot slit 12 in the direction of the air gap 15.

[0057] The slots 8 of the stator 2 and / or the slots of the rotor 14 extend in an axially parallel manner or they are inclined from one end face to the other end face up to two slot pitches or three slot pitches.

[0058] The rotor 14 is connected to the shaft 26 in a rotationally fixed manner and is mounted so as to be rotatable about an axis 27. During the production of the stator 2, the slot slits 12 of the slot 8 are used to draw the winding system 25, which is in particular formed as a wire bundle of a coil, through the slot slits 12 by means of a cutter tool into the corresponding slot 8. During the drawing-in operation, the wire insulation of the coil is at risk of being scratched at the edges of the slot slits 12, thereby impairing the insulation properties of the wire.

[0059] Figure 2 A principle cross section of a stator 2 is shown, which has a stator bore 30, a yoke back 3 of the stator and a slot 8 pointing toward the axis 27. In this case, the slot 8 has a slot bottom 9, a slot wall 10 and also a slot slit 12. Thus, the slot 8 is created by adjacent teeth 5 when viewed in the circumferential direction. In this case, the slot wall 10 is arranged in the region of the tooth shaft 4, and the tooth top 6, in particular the end 7 of the tooth top, forms the slot slit 12. The winding system 25 is positioned in the slot 8 via the slot slit 12 and therefore along the end 7 of the adjacent tooth top 6. In this region, damage to the insulation of the wire of the winding system 25 can occur during the pull-in process.

[0060] According to the prior art, the winding 25 is for this reason arranged in the following manner as in principle from Figure 1 As seen in FIG. 4 , it is introduced into the groove 8 .

[0061] Firstly, according to FIG. 3 , the side walls of the pull-in sheet or the sheet-like tool 13 are positioned in the slot slit 12 in order to ensure that the wire is protected from the slot teeth, in particular from the ends of the slot teeth, during the pull-in. This is made possible by the fact that the corresponding wire bundle is locally tapered according to FIG. 4 . This is necessary because the wire bundle of the winding system 25 is pulled in through the slot slit 12 for positioning in the slot 8 and is thus pulled in almost axially along the slot teeth 5. Thus, during the pull-in, the pull-in is carried out perpendicularly to the axial stacking of the laminated core 23 or perpendicularly to the direction of movement of the sheet-like tool 13, thereby preventing the insulation of the wire from being damaged.

[0062] This problem is solved by the protective side walls of the insert plate, which are made of smooth polished steel. The disadvantage here is that the effective width of the slot is significantly reduced (typical values ​​are: slot: 3.2 mm, narrowing: 2×0.3 mm plate thickness+0.4 mm (tolerance and “plate gap”)=1 mm), that is, in this specific case, it is reduced by about 30%.

[0063] Therefore, in order to obtain the basis Figure 5 The slot 8 with the winding system 25 according to the present invention (according to Figure 6 The coating 16 is applied to the ends of the tooth tips 6, that is to say in the region of the slot slits 12. This can be performed, for example, by a spraying tool 21 which is moved along one or more slot slits 12 by an axial movement with superimposed rotation.

[0064] according to Figure 7 , the edges of the end 7 are thus coated. In this case, the corners of the end 7 (facing the groove and facing the air gap) and its preferably parallel side walls are coated.

[0065] This coating, which provides a protective effect of pulling into the sheet, is applied in an additive manner, preferably by spraying. The stainless steel sidewalls of the sheet are 0.3 mm, wherein a tolerance of 2 x 0.1 mm is taken into account regarding the tooth tops 6. The total slot loss is therefore recorded as 0.8 mm + 0.2 mm (additional "sheet clearance")

[0066] Therefore, according to Figure 8 For the pulling-in process of the winding 25, the blade of the blade tool 13 thus engages in a positively locking manner with the adjacent tooth top 6, that is, the coated slot slit 12 on the side of the stator bore 30. In this case, the slot 8 is provided with a slot lining 19, that is, a slot box, usually a polyester multilayer composite material with aramid felt, with a thickness of about 300 micrometers.

[0067] Preferably, adjacent sheets and coated slot slits 12 have the same width.

[0068] Then, according to Fig. 9 , the pulling-in process of the winding 25 into the slot 8 is performed via the relatively wide slot slit 12 .

[0069] The coating 16 remains at the slot slit 12. After the winding 25 is pulled in through the slot slit 12, according to Fig.10 , the slot 8 is covered by the covering slide plate 20. Then, winding heads are formed at both end surfaces of the stator 2 and the stator 2 is cast.

[0070] The laminated core 23 of the stator 2 has a stacking tolerance which is evident in the relatively small gaps and edges between the individual laminated cores 11 , but also in the tooth tips 6 at the end 7 .

[0071] according to Fig.11 The coating 16 compensates for these gaps and edges or possible stacking tolerances and covers the lamination edges. This significantly reduces the roughness of the macroscopic surface, which ideally, but not necessarily, forms a continuously smooth surface. Fig.11 and Fig.12 The profile can also form gentle curves in the area of ​​gaps and edges. The reduction in microscopic surface roughness is determined by the choice of polymer and its filler additives.

[0072] Therefore, at a time before the winding insertion process, a plastic layer is applied to at least the end face 7 of the tooth 6, which plastic layer covers the lamination contour (at the end face, the individual laminations with lamination edges). It is important here that the applied plastic layer covers at least the lamination edges for the subsequent insertion operation in the winding 25. A continuous and smooth plastic surface without interruptions is not absolutely necessary here, but is meaningful in order to improve the sliding wear during the insertion process, i.e. to further reduce the insertion forces.

[0073] In this case, the maximum thickness of the coating 16 in the above-mentioned region is 50 micrometers. Therefore, the narrowing of the slot slit 12 is to a smaller extent, which simplifies the pulling-in process and in particular reduces the pulling-in force required by the sheet tool. In addition, winding wires with larger diameters can also be used.

[0074] Therefore, the thickness of the applied coating 16 must be only a few micrometers to a maximum of 50 micrometers in order to statistically ensure that all lamination edges are coated with at least a few micrometers of plastic so that the wires of the winding 25 that slide over, in particular the enameled wires of the winding, are not subjected to any mechanical damage during the pulling in process, in particular their insulation is not scratched.

[0075] Suitable plastic coatings in this case are thermosetting varnishes (e.g. polyetherimide, polyurethane, epoxy resin, polysiloxane, polysilazane, etc.) which can be sprayed on in a thin layer in a diluted manner with the aid of a solvent and harden within a few hours at room temperature by using a two-component material. This time interval can also be shortened by slight heating (e.g. 70° C. for a few hours).

[0076] Another variant for applying a thin plastic layer is to use a soluble thermoplastic, such as polyethylene glycol, polyvinyl pyrrolidone or polyvinyl alcohol, which after drying of the solvent forms a physically dry layer within a short time and thus produces a protective film of the above-mentioned thickness. In this case, a high molecular weight product is used, the molecular weight of which is at least the subsequent insulation grade of the motor 1.

[0077] Another possibility to obtain such a layer is to use high melting point waxes and high molecular weight greases, which can then also be sprayed on at high temperatures (eg >250° C.) and provide a protective film by immediate cooling.

[0078] Another possibility is to use high-melting-point thermoplastic hot melt adhesives (e.g., polyamides), which are centrifuged (sprayed) onto the substrate in the form of a spiral through a rotating nozzle of the spraying tool 21, cooled and solidified into a layer when it touches the end. A large number of different spray patterns (closed, porous), layer thicknesses and adhesion behaviors are achieved via material temperature, compressed air temperature, pressure, nozzle geometry, etc. The cooled surface then has a sliding ability similar to that of a smooth thermoplastic shell.

[0079] Furthermore, it is possible to add sliding-capable filler additives to the aforementioned plastics, which further improve the sliding wear of the coating 16 and, provided that the additive has a form factor (i.e. is in the form of a plate or rod), bridges the gap between two axially adjacent laminations 11 in the laminated core 23. In this case, possible sliding additives are boron nitride, graphite and polytetrafluoroethylene, which are added to the plastic matrix in a volume percentage of between 1% and 25%.

[0080] As a result of the sprayed-on coating 16 , basically independently of the coating composition, only a reduction of the slot 12 by a maximum of 2×50 μm is achieved.

[0081] Thus, in the above example, the tooth top 6 can be widened to the minimum necessary width of the slot slit 12, which includes but is not limited to being determined by the wire used, because the wire can slide over the sprayed coating 16 without being damaged at the lamination edges.

[0082] According to the invention, during the drawing of the winding into the slot 8 via the slot slit 12, the protection function of the wire harness is achieved by a coating 16 which acts as an insulating layer. It can be significantly thinner and does not require any tolerances for the drawing-in sheet extending into the slot slit 12, without reducing the effective slot slit during the drawing-in of the winding using standard tools, whereby the effective slot tooth width can be increased and thus the efficiency of the motor can be increased.

[0083] Fig.13According to the example, a slot slit 12 is shown which is formed by the ends 7 of adjacent tooth tips 6 when viewed in the circumferential direction. In this case, the maximum possible width of the slot slit 12 is 17. The sheet body that reaches into the slot slit 12 through the sheet-like tool reduces the width of the slot slit 12 to the sheet body width 29. In contrast, the coating 16 according to the invention only reduces the width of the slot slit 12 to the coating width 28.

[0084] In the method according to the invention for producing a stator 2 for an electric motor 1 , it is therefore possible to dispense with inserting the side walls of the laminae, in particular in the slot slits 12 , without having to worry about any damage to the wire enamel of the winding during pulling in.

[0085] The coating 16 according to the invention of the slot slots 12 therefore allows correspondingly larger tooth tips 6 or wider tooth tips when viewed in the circumferential direction, which, in the case of relatively small slot slot widths, increases the efficiency of the electric motor 1 by up to one percentage point.

Claims

1. A method for producing a stator (2) of an electric motor (1), the method comprising the following steps: - a stacked laminated core (23) having at least one stator bore (30), an axially extending slot (8) and a slot slit (12) directed toward the stator bore (30), in, When viewed in the circumferential direction, the groove (8) is formed by two directly adjacent tooth shafts (4), a section of the corresponding tooth top (6), the groove slit (12) and the groove bottom (9), wherein the groove slit (12) is formed by two mutually opposite ends (7) of adjacent tooth tops (6) when viewed in the circumferential direction, - coating the end portion (7) with a friction-reducing coating (16), in particular an electrically insulating coating, - pulling a winding (25), in particular a prefabricated winding, in particular a coil-shaped round wire bundle, into the slot (8) via the slot slit (12), - The application to the end (7) of the tooth tip (6) is carried out by means of a centrifugal process or a nozzle, in particular a rotating nozzle, wherein the centrifugal device or the spraying device is moved axially in the stator bore (30) during the application and thereby one or more slots (12) with the anti-friction coating (16) are provided.

2. The method for producing a stator (2) of an electric motor (1) according to claim 1, It is characterized in that The anti-friction coating (16) is sprayed onto the end (7) as a diluted thermosetting varnish.

3. The method for manufacturing a stator (2) of an electric motor (1) according to claim 1, It is characterized in that The friction-reducing coating (16) is applied as a soluble thermoplastic at the end (7).

4. The method for manufacturing a stator (2) of an electric motor (1) according to claim 1, It is characterized in that The anti-friction coating (16) is sprayed on the end (7) by means of high melting point wax or grease.

5. The method for manufacturing a stator (2) of an electric motor (1) according to claim 1, It is characterized in that The friction-reducing coating (16) is applied to the end portion (7) by means of a thermoplastic hot melt adhesive.

6. Method for producing a stator (2) for an electric motor (1) according to any one of the preceding claims, It is characterized in that The winding (25) is pulled into one or more slots (8) by means of a sheet-like tool (13), wherein the sheet-like tool (13) engages on the side of the slot slit (12) facing the stator bore (30).

7. A stator (2) of an electric motor (1), said stator being manufactured according to any one of claims 1 to 6, It is characterized in that The slot (12) is coated.

8. The stator (2) of the electric motor (1) according to claim 7, It is characterized in that The slot slit (12) corresponds to x times the wire diameter of the winding (25), wherein x>1。 9. An electric motor (1) having a stator (2) according to claim 7 or 8, It is characterized in that The efficiency of the electric motor (1) is at least 95%.

10. Use of an electric motor (1) according to claim 9 for a drive, in particular for a drive in continuous operation, such as a fan, a compressor, a pump or the like.

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