ELECTRICAL MACHINE

Abstract

A method for producing a stator for an electrical machine may first include providing a stator having a ring-shaped stator body, from which a plurality of stator teeth arranged spaced apart from one another along a circumferential direction of the stator body, for accommodating stator windings, protrude, wherein a space, in each case, may be embodied between two stator teeth adjacent in the circumferential direction. The method then may include first injection molding at least two stator teeth, which are adjacent in the circumferential direction, with a plastic, arranging at least one stator winding in the space between the at least two stator teeth, and second injection molding the stator winding with the plastic, so that at least one of an air gap and an air trap formed between the at least two stator teeth first injection molded and the stator winding is filled with the plastic.

Claims

1. A method for producing a stator for an electrical machine, comprising: providing a ring-shaped stator body, from which a plurality of stator teeth, which are arranged spaced apart from one another along a circumferential direction of the stator body, for accommodating stator windings protrude, wherein a space is in each case embodied between two stator teeth adjacent in the circumferential direction; first injection molding at least two stator teeth, which are adjacent in the circumferential direction, with a plastic; arranging at least one stator winding in the space; and second injection molding the at least one stator winding arranged in the space with the plastic, so that at least one of an air gap and an air trap formed between the at least two stator teeth first injection molded and the at least one stator winding after arranging the at least one stator winding in the space is filled with the plastic.

2. The method according to claim 1, further comprising using an electrically insulating plastic in response to at least one of the first injection molding and the second injection molding.

3. The method according to claim 1, further comprising: introducing at least one masking into the space between the two stator teeth; and at least partially injection molding each of the at least one masking with the plastic, so that a volume of the space, which is filled by the at least one masking in response to being at least partially injection molded, remains free so as to embody a cooling duct.

4. The method according to claim 3, wherein the at least partially injection molding of the at least one masking takes place one of: in the course of the second injection molding; or separately from the second injection molding.

5. The method according to claim 3 wherein the at least one masking is arranged in an area of at least one of a radially inner end section or a radially outer end section of the space, and the cooling duct is arranged in the at least one of a radially inner end section and a radially outer end section in response to the at least partially injection molding of the at least one masking.

6. The method according to claim 3, wherein a protective coating, which is arranged in the space at least partially limits or surrounds the cooling duct in a cross section perpendicular to an axial direction, is embodied by the at least partially injection molding of the at least one masking.

7. The method according to claim 6, wherein embodying of the protective coating takes place one of: in the course of the second injection molding; or separately from the second injection molding.

8. The method according to claim 6, wherein the protective coating limits the cooling duct at least one of radially on an inside and radially on an outside in the cross section perpendicular to the axial direction.

9. The method according to claim 6, wherein the protective coating limits the cooling duct in the circumferential direction of the stator in the cross section perpendicular to the axial direction.

10. The method according to claim 3, wherein introducing at least one masking into the space includes introducing a first masking and a second masking into the space, so that a first cooling duct and a second cooling duct are formed via at least partially injection molding the first masking and the second masking, wherein the first cooling duct is arranged in a radially inner end section of the space and the second cooling duct in a radially outer end section of the space.

11. The method according to claim 1, wherein the first injection molding includes injecting the plastic onto surface sections of the at least two stator teeth defining the space.

12. The method according to claim 1, wherein: the plastic is applied to a surface section of the stator body limiting the space in the course of the first injection molding.

13. The method according to claim 11, wherein an electrically insulating layer, which covers the surface sections of the at least two stator teeth defining the space is formed from the plastic injected onto the surface sections.

14. The method according to claim 1, wherein at least one phase insulation arranged in the space, which divides the space into a radially inner subspace and a radially outer subspace, is embodied in the course of the injection molding with the plastic, so that first conductor elements of the stator winding, which embody a first phase winding, are arranged in the radially inner subspace, and second conductor elements of the stator winding, which embody a second phase winding, which is electrically insulated with respect to the first phase winding, are arranged in the radially outer subspace.

15. The method according to claim 14, wherein the phase insulation is formed in response to one of the first injection molding or the second injection molding, or in separately from the first and second injection moldings.

16. The method according to claim 14, wherein the phase insulation extends along the circumferential direction and connects an insulation layer of the plastic arranged on adjacent stator teeth to one another.

17. The method according to claim 1, wherein: the plastic injected onto surface sections of the stator teeth is formed from an electrically insulating first plastic material; the plastic embodying at least one phase insulation, which divides the space into a radially inner subspace and a radially outer subspace, is formed by a second plastic material; and the plastic embodying at least one protective coating, which at least partially surrounds a respective cooling duct in the space, is formed by the second plastic material or by a third plastic material.

18. The method according to claim 17, wherein at least one of: the second plastic material is embodied to be electrically insulating or electrically conductive; and the third plastic material is embodied to be electrically insulating or electrically conductive.

19. The method according to claim 17, wherein at least one of the first plastic material, the second plastic material, and the third plastic material is one of a thermoplastic or a thermoset.

20. The method according to claim 17, wherein at least one of: at least two of the first plastic material, the second plastic material, and the third plastic material have identical heat conductivities; and at least two of the first plastic material, the second plastic material, and the third plastic material have different heat conductivities.

21. The method according to claim 17, wherein at least one of: at least two of the first plastic material, the second plastic material, and the third plastic material are identical materials; and at least two of the first plastic material, the second plastic material, and the third plastic material are different materials.

22. The method according to claim 1, wherein injection molding or filling of the space with the plastic takes place in such a way that an air gap is no longer present in the space after the injection molding or filling.

23. The method according to claim 1, wherein the space is embodied in a substantially gap-free manner by of the plastic.

24. A stator, produced by: providing a ring-shaped stator body, from which a plurality of stator teeth, which are arranged spaced apart from one another along a circumferential direction of the stator body, for accommodating stator windings protrude, wherein a space is in each case embodied between two stator teeth adjacent in the circumferential direction; first injection molding at least two stator teeth, which are adjacent in the circumferential direction, with a plastic; arranging at least one stator winding in the space; and second injection molding the at least one stator winding arranged in the space with the plastic, so that at least one of an air gap and an air trap formed between the at least two stator teeth first injection molded and the at least one stator winding after arranging the at least one stator winding in the space is filled with the plastic.

25. An electrical machine, comprising: a stator produced by: providing a ring-shaped stator body, from which a plurality of stator teeth, which are arranged spaced apart from one another along a circumferential direction of the stator body, for accommodating stator windings protrude, wherein a space is in each case embodied between two stator teeth adjacent in the circumferential direction; first injection molding at least two stator teeth, which are adjacent in the circumferential direction, with a plastic; arranging at least one stator winding in the space; and second injection molding the at least one stator winding arranged in the space with the plastic, so that at least one of an air gap and an air trap formed between the at least two stator teeth first injection molded and the at least one stator winding after arranging the at least one stator winding in the space is filled with the plastic; and a rotor, which is embodied to be rotatable about an axis of rotation relative to the stator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In each case schematically:

[0053] FIG. 1 shows an example of an electrical machine according to the invention in a longitudinal section along the axis of rotation of the rotor,

[0054] FIG. 2 shows the stator of the electrical machine according to FIG. 1 in a cross section perpendicular to the axis of rotation of the rotor,

[0055] FIG. 3 shows a detail illustration of the stator of FIG. 2 in the area of a space between two stator teeth, which are adjacent in the circumferential direction,

[0056] FIG. 4 shows a further development of the example according to FIG. 3 comprising an additional, second cooling duct,

[0057] FIG. 5 shows an option of the example according to FIG. 3, in the case of which the stator windings are not formed by winding rods, but by winding wires formed in a plastic compound.

[0058] FIGS. 6-9 show illustrations illustrating the sequence of the method according to the invention.

[0059] FIG. 10 shows a first further development of the example of FIG. 3,

[0060] FIG. 11 shows a second further development of the example of FIG. 3.

DETAILED DESCRIPTION

[0061] FIG. 1 illustrates an example of an electrical machine 1 according to the invention in a sectional illustration. The electrical machine 1 is dimensioned in such a way that it can be used in a vehicle, preferably in a road vehicle.

[0062] The electrical machine 1 comprises a rotor 3, which is only illustrated in a roughly schematic manner in FIG. 1, and a stator 2. For clarification purposes, the stator 2 is illustrated in FIG. 2 in a cross section perpendicular to the axis of rotation D along the sectional line II-II of FIG. 1 in a separate illustration. According to FIG. 1, the rotor 3 has a rotor shaft 31 and can have a plurality of magnets, which are not illustrated in more detail in FIG. 1, the magnetic polarization of which alternates along the circumferential direction U. The rotor 3 can be rotated about an axis of rotation D, the position of which is determined by the center longitudinal axis M of the rotor shaft 31. The axis of rotation D defines an axial direction A, which extends parallel to the axis of rotation D. A radial direction R is perpendicular to the axial direction A. A circumferential direction U rotates around the axis of rotation D.

[0063] As can be seen in FIG. 1, the rotor 3 is arranged in the stator 2. The electrical machine 1 shown here is thus a so-called internal rotor. However, a realization as so-called external rotor is also conceivable, in the case of which the rotor 3 is arranged outside of the stator 2. The rotor shaft 31 is supported on the stator 2 in a first shaft bearing 32a and, axially spaced apart therefrom, in a second shaft bearing 32b so as to be rotatable around the axis of rotation D.

[0064] In the known manner, the stator 2 furthermore comprises a plurality of stator windings 6, which can be electrically energized so as to generate a magnetic field. The rotor 3 is set into rotation by means of magnetic interaction of the magnetic field, which is generated by the magnets of the rotor 3, with the magnetic field, which is generated by the electrically conductive stator windings 6.

[0065] It can be gathered from the cross section of FIG. 2 that the stator 2 can have a ring-shaped stator body 7, for example of iron. The stator body 7 can in particular be formed of a plurality of stator body plates (not shown), which are stacked on top of one another along the axial direction A and which are adhered to one another. A plurality of stator teeth 8, which extend along the axial direction A, protrude away from the stator body 7 radially to the inside, and which are arranged spaced apart from one another along the circumferential direction U, are molded on the stator body 7 radially on the inside. Each stator tooth 8 supports a stator winding 6. Together, the individual stator windings 6 form a winding arrangement. Depending on the number of the magnetic poles, which are to be formed by the stator windings 6, the individual stator windings 6 of the entire winding arrangement can be electrically wired together in a suitable manner.

[0066] During operation of the machine 1, the electrically energized stator windings 6 generate waste heat, which has to be dissipated from the machine 1, in order to prevent an overheating and damages to or even destruction of the machine 1 associated therewith. The stator windings 6 are thus cooled with the help of a coolant K, which is guided through the stator 2 and which absorbs the waste heat generated by the stator windings 6 by means of heat transfer.

[0067] To guide the coolant K through the stator 2, the machine 1 comprises a coolant distributor chamber 4, into which a coolant K can be introduced via a coolant inlet 33. Along the axial direction A, a coolant collector chamber 5 is arranged at a distance from the coolant distributor chamber 4. The coolant distributor chamber 4 communicates fluidically with the coolant collector chamber 5 by means of a plurality of cooling ducts 10, of which only a single one can be seen in the illustration of FIG. 1. In a cross section perpendicular to the axial direction A, which is not shown in the figures, the coolant distributor chamber 4 and the coolant collector chamber 5 can each have a ring-shaped geometry. A plurality of cooling ducts 10, which each extend along the axial direction A from the ring-shaped coolant distributor chamber 4 to the ring-shaped coolant collector chamber 5, are arranged at a distance from one another along the circumferential direction U. The coolant K introduced into the coolant distributor chamber 4 via the coolant inlet 33 can thus be distributed to the individual cooling ducts 10. After the flow-through of the cooling ducts 10 and the absorption of heat from the stator windings, the coolant K is collected in the coolant collector chamber 5 and is discharged from the machine 1 again via a coolant outlet 34 provided on the stator 2.

[0068] As can be seen in the illustrations of FIGS. 1 and 2, the stator windings 6 and the coolant ducts 10 are arranged in spaces 9, which are in each case embodied between two stator teeth 8, which are adjacent in the circumferential direction U. Said spaces 9 are also known to the pertinent person of skill in the art as so-called stator grooves or stator slots, which extend along the axial direction A, as do the stator teeth 8.

[0069] The illustration of FIG. 3 will be described below, which shows a space 9 embodied between two stator teeth 8hereinafter also referred to as stator teeth 8a, 8bwhich are adjacent in the circumferential direction U, in a detail illustration.

[0070] As illustrated by FIG. 3, the space 9 has an opening 52 radially on the inside, is thus embodied so as to be open radially on the inside. In the example of FIG. 3, the cooling duct 10 is arranged in the area of a radially inner end section 56a of the space 9 or of the stator groove 54, respectively, thus in the area of the opening 52.

[0071] To improve the heat transfer of the waste heat generated by the stator windings 6 to the coolant K flowing through the cooling ducts 10, an electrically insulating and heat conducting plastic 11 is arranged in addition to a cooling duct 10 and a stator winding 6 in the spaces 9 in accordance with FIG. 3.

[0072] The plastic 11 is preferably introduced into the space 9 by means of injection molding.

[0073] As can be seen in FIG. 3, the plastic 11 is arranged on surface sections 50a, 50b, 50c of two stator teeth 8, which are adjacent in the circumferential direction U and which, together, limit the space 9. It is ensured in this way that the cooling duct 10 arranged in the space 9 as well as the stator winding 6 arranged in the same space 9 is in each case electrically insulated relative to the stator teeth 8 by means of the electrically insulating plastic 11. The stator winding 6 is furthermore connected to the cooling duct 10 in a heat conducting manner via the plastic 11, so that waste heat generated in or by the stator winding 6, respectively, can be transferred to the coolant K flowing through the cooling duct 10 via the plastic 11 and can thus be discharged from the stator winding 6.

[0074] A surface section 50a of the two stator teeth 8a, 8b, which are adjacent in the circumferential direction U, located radially opposite the opening 52hereinafter identified as fist surface section and additionally provided with reference numeral 50aforms a so-called groove base of the stator groove 54 formed by the space 9. A first front side, which limits the space 9 in the circumferential direction U, of a first one of the two adjacent stator teeth 8hereinafter additionally identified with 8aembodies a second surface section 50b. A second front side, which also limits the space 9 in the circumferential direction U, of a second one of the two adjacent stator teeth 8hereinafter additionally identified with 8bembodies a third surface section 50c, which is located opposite the second surface section 50b in the circumferential direction U.

[0075] The plastic 11 arranged on the three surface sections 50a, 50b, 50c embodies an electrically insulating and heat conducting insulating layer 51, which covers the surface sections 50a, 50b, 50c. A layer thickness d of the insulating layer 51 can, for example, be between 0.2 mm and 0.5 mm.

[0076] It can be seen that the plastic 11 does not only embody the electrical insulating layer 51, but also a first protective coating 75, which is arranged in the space 9 and which surrounds and limits the cooling duct 10 in this way. The provision of a tube body or the like for the fluid-tight limitation of the cooling duct 10 in such a way that no coolant K can escape therefrom, is thus superfluous.

[0077] In the example scenario of FIG. 3, the first protective coating 75 closes the opening 52 of the space 9, which is embodied so as to be open, or of the stator groove 54, respectively. As can further be seen in FIG. 3, the stator winding 6 is also not only electrically insulated relative to the cooling duct 10 via the plastic 11, which forms the first protective coating 75, but is also connected thereto in a heat conducting manner, so that waste heat generated in or by the stator winding 6, respectively, can also be transferred to the coolant K flowing through the cooling duct 10 via the first protective coating 75.

[0078] According to FIG. 3, the plastic 11 cannot only embody the first protective coating 75 and the insulating layer 51, butalternatively or additionallyalso a phase insulation 58 arranged in the space 9 or in the stator groove 54, respectively. The phase insulation 58 divides the space 9 into a radially inner and into a radially outer subspace 59a, 59b.

[0079] The phase insulation 58 advantageously extends along the circumferential direction U. The phase insulation 58 preferably connects the second surface section 50b to the third surface section 50c.

[0080] The first conductor elements 60a are arranged in the radially inner subspace 59a and the second conductor elements 60b in the radially outer subspace 59b.

[0081] The first cooling duct 10 arranged in the area of the radially inner end section 54a is arranged in the radially inner subspace 59a, which is formed of plastic 11 by means of the phase insulation 58.

[0082] As can be seen in FIG. 3, the stator winding 6 arranged in the space 9 comprises first conductor elements 60a and second conductor elements 60b, which are arranged next to one another and at a distance from one another along the radial direction R in the space 9. An air gap 61, which can preferably extend along the circumferential direction U, is embodied between two conductor elements 60, 60b, which are each adjacent along the radial direction R. The plastic 11 thereby embodies a gap filling 62, with which the air gap 61 is filled completely.

[0083] An air gap 61, which can preferably extend along the radial direction R, is embodied in a similar manner between the first and second conductor elements and the electrical insulating layer 51 arranged on the surface sections 50a, 50b, 50c of the stator teeth 8, 8a, 8b. The plastic 11 thereby embodies a gap filling 62, with which the air gap 61 is filled completely.

[0084] All first and second conductor elements 60a, 60b are thus surrounded by the electrically insulating and heat conducting plastic 11 in the cross section perpendicular to the axial direction A as illustrated in FIG. 3.

[0085] The first and second conductor elements 60a, 60b, each as first or second winding rods 65a, 65, respectively, are made of an electrically conductive and mechanically stiff material.

[0086] In the cross section perpendicular to the axial direction A. the first and second winding rods 65a, 65b each have the geometry of a rectangle 66 comprising two narrow sides 67 and two broad sides 68. The two broad sides 68 of two adjacent winding rods 65a or 65b, respectively, are located opposite one another with respect to the radial direction R and limit the respective air gap 61 in the radial direction R in this way.

[0087] FIG. 4 shows a further development of the example of FIG. 3. The example of FIG. 4 differs from that of FIG. 3 in that a cooling duct 10 is arranged in the area of a radially outer end section 56a of the space 9 or of the stator groove 54, respectively, which is located opposite to the radially inner end section 56a with respect to the radial direction R of the space 9.

[0088] In the example of FIG. 4, the plastic 11analogously to the first protective coating 75 of the coolant 10embodies a second protective coating 75, which is arranged in the space 9 and which limits and thus surrounds the additional cooling duct 10. As can be seen in FIG. 4, the additional cooling duct 69, which is arranged in the radially outer end section 56b, is arranged in the radially outer subspace 59b of the space 9 or of the stator groove 54, respectively, which is formed by means of the phase insulation 58 formed by the plastic 11.

[0089] In the event that the plastic 11 cracks due to thermal overload or is damaged in another way, an unwanted electrical short-circuit of the stator winding 6 can be avoided in this way by means of the material of the stator body 7 or of the stator teeth 8 or 8a, 8b, respectivelytypically iron or another suitable, electrically conductive material.

[0090] FIG. 5 shows an option of the example of FIG. 3. In the example of FIG. 5, the plastic forms a plastic compound, into which the stator winding is embedded. In the example of FIG. 5, the conductor elements 65 of the stator winding 6 are formed by means of winding wires 72, which are part of a distributed winding.

[0091] Reference will be made below to FIG. 1 again. According to FIG. 1, the stator 2 comprising the stator body 7 and the stator teeth 8 is axially arranged between a first and a second end shield 25a, 25b.

[0092] As can be seen in FIG. 1, a portion of the coolant distributor chamber 4 is arranged in the first end shield 25a and a portion of the coolant collector chamber 5 in the second end shield 25b. The coolant distributor chamber 4 and the coolant collector chamber 5 are thus each partially formed by a hollow space 41a, 41b, which is provided in the plastic 11. By means of a hollow space 42a embodied in the first end shield 25a, the first hollow space 41a is thereby supplemented to form the coolant distributor chamber 4. The second hollow chamber 41b is accordingly supplemented to form the coolant collector chamber 5 by means of a hollow space 42b embodied in the second end shield 25b. In the case of the above-described embodiment option, the plastic 11 thus at least partially limits the coolant distributor chamber 4 as well as the coolant collector chamber 5.

[0093] A coolant supply 35, which fluidically connects the coolant distributor chamber 4 to a coolant inlet 33, which is provided on the first end shield 25a on the outside, in particular circumferentially as illustrated in FIG. 1, can further be embodied in the first end shield 25a. A coolant discharge 36, which fluidically connects the coolant collector chamber 5 to a coolant outlet 34, which is provided on the end shield 25b on the outside, in particular circumferentially as illustrated in FIG. 1, can accordingly be embodied in the second end shield 25b. This provides for an arrangement of the coolant distributor chamber 4 or of the coolant collector chamber 5, respectively, radially outside on the first or second end section 14a, 14b, respectively, of the respective stator winding 6 and also in the extension of these end sections 14a, 14b along the axial direction A. The end sections 14a, 14b of the stator windings 6, which are particularly loaded thermally during operation of the machine 1, are cooled particularly effectively by means of this measure.

[0094] According to FIG. 1, the plastic 11 can also be arranged on an outer circumferential side 30 of the stator body 7 and can thus embody a plastic coating 11.1 on the outer circumferential side 30. The stator body 7 of the stator 2, which is typically formed of electrically conductive stator plates, can thus be electrically insulated against the surrounding area. The provision of a separate housing for accommodating the stator body 7 can thus be forgone.

[0095] The method according to the invention will be described below in an exemplary manner:

[0096] According to FIG. 6, the stator 2 comprising the two stator teeth 8a, 8b, which are adjacent in the circumferential direction U, and the space 9 limited by these two stator teeth 8a, 8b is arranged in a first step a).

[0097] According to a second step b), the two stator teeth 8a, 8b, which are adjacent in the circumferential direction U, are injection molded with the electrically insulating and heat conducting plastic 11. In the course of the injection molding of the stator teeth 8a, 8b, electrically insulating plastic 11 is injected onto the surface sections 50b, 50c of the two adjacent stator teeth 8a, 8b, which limit the space 9. An electrically insulating layer 51, which covers the surface sections 50b, 50c of the two adjacent stator teeth 8, 8a, 8b, which limit the space 9, is formed by means of the plastic 11, which is injected onto the surface sections 50b, 50c of the stator teeth 8a, 8b. The insulating layer 51 likewise covers a surface section 50a of stator body 7, which limits the space 9 radially on the outside.

[0098] As furthermore illustrated in FIG. 6, a phase insulation 58, which divides the space 9 into a radially inner and into a radially outer subspace 59a, 59b, can be formed in the space 9 in the course of the injection molding with the plastic 11 or by means of injection molding with the plastic 11, respectively. First conductor elements of the stator winding 6, which embody a first phase winding 70a, can then later be arranged in the radially inner subspace 59a. Second conductor elements of the stator winding 6, which embody a second phase winding 70b, which is electrically insulated with respect to the first phase winding 70b, can accordingly be arranged in the radially outer subspace 59b.

[0099] The phase insulation 58 advantageously extends along the circumferential direction U of the stator 2, so that it connects the two insulating layers 51 of the plastic 11, which are arranged on the adjacent stator teeth 8a, 8b, to one another.

[0100] In a further, third method step c), stator windings 6 are arranged on the stator teeth 8, 8a, 8b. This means that, as shown in FIG. 7, at least one stator winding 6 is partially arranged in the space 9.

[0101] As can be seen in FIG. 7, the stator winding 6 arranged in the space 9 has first conductor elements 60a and second conductor elements 60b. The first and second conductor elements 60a, 60b are arranged next to one another and at a distance from one another in the space 9 along the radial direction R of the stator 2 or of the stator body 7, respectively.

[0102] In step c), the first conductor elements 60a of the stator winding 6 are arranged in the radially inner subspace 59a, and the second conductor elements 60b of the stator winding 6 are arranged in the radially outer subspace 59b. The first conductor elements 60a can thus be electrically connected to one another for connection to a common first phase of an electrical current source (not shown). The second conductor elements 60-b can accordingly be electrically connected to one another for connection to a common second phase of the electrical current source.

[0103] The first and second conductor elements 60a, 60b are embodied as winding rods 65a, 65b of an electrically conducting material and so as to be mechanically stiff. After the arrangement in the space 9, the winding rods 65a, 65b have the geometry of a rectangle 66 comprising two narrow sides 67 and comprising two broad sides 68 in the cross section perpendicular to the axial direction A.

[0104] For the later embodiment of a cooling duct 10, a masking 57 can be introduced into the space 4 between the two stator teeth 8a, 8b, namely in the area of a radially inner end section 56a of the space 9, as shown for example in FIG. 7.

[0105] As can be seen in FIG. 7, a respective air gap 61, in which in particular no plastic 11 is present, can be created after the arrangement of the stator winding 6 comprising the first and second conductor elements 60a, 60b in the space 9 between two respective adjacent conductor elements 60a, 60b. This air gap 61 can also be created between the conductor elements 60a, 60b and the insulating layer 51 arranged on the surface sections 50a, 50b, 50c. Instead of an air gap 61, the embodiment of one or of a plurality of air traps (not shown) is also conceivable.

[0106] According to FIG. 8, a further injection process now takes place. In the course of a second injection molding according to a fourth method step d), the stator winding 6, which is arranged in the space 9 and which comprises the first and second conductor elements 60a, 60b, is injection molded with the plastic 11, so that at least one air gap 61, preferably all air gaps and air traps, which are present in the space 9, are filled with the plastic 11. After the filling of the air gap 61 with the gap filling 62 of the plastic 11, the first and second conductor elements 60a, 60b are in each case completely surrounded by the electrically insulating and heat conducting plastic in the cross section perpendicular to the axial direction A. The injection molding or filling, respectively, of the space 9 with the plastic 11 in particular takes place in such a way that an air gap 11 or air trap, respectively, is no longer present in the space 9 after the injection molding or filling, respectively.

[0107] According to FIG. 8, the injection molding of the masking 57 can also take place in the course of the second injection molding. In the course of this injection process, the masking 57 is injection molded with the plastic 11, so that the volume of the space 9 filled by the masking 57 remains free so as to embody a cooling duct 10 in response to this injection molding. It is conceivable in one option that the injection molding of the masking 57 is performed in a separate method step.

[0108] After the removal of the masking 57, the desired cooling duct 10 is formed, which is illustrated in FIG. 9.

[0109] In one option of the example, the masking 57 cannot be arranged in the area of the radially inner end section 56a, but in the area of a radially outer end section 56b of the space 9 (not shown in FIG. 8/9). The cooling duct 10 is then created accordingly in the radially outer end section 56b (not shown in FIG. 8/9).

[0110] The combined use of two maskings 57 in the radially inner as well as radially outer end section 56a, 56b is also conceivable according to FIG. 10, so that two cooling ducts 10 are created accordingly, so that a first cooling duct 10 is created in the radially inner end section 56a and a second cooling duct 10 in the radially outer end section 56b. The first cooling duct 10 is thus arranged in the radially inner subspace 59a comprising the first conductor elements 60a. The second cooling duct 10 is accordingly arranged in the radially outer subspace 59b comprising the second conductor elements 60b.

[0111] The phase insulation 58 (see FIG. 6) can be formed in response to the injection molding of the stator teeth 8, 8a, 8b or, alternatively, in response to the injection molding of the stator winding 6 or, alternatively, in a separate method step.

[0112] To ensure an optimal electrical insulation of the cooling duct 10 relative to the stator teeth 8a, 8b or the stator winding 6, respectively, a protective coating 75, which is arranged in the space 9 and which limits or surrounds the cooling duct 10, respectively, in the cross section perpendicular to the axial direction A, can be embodied in a further development according to FIG. 11 by means of additional injection molding of the masking 57 with plastic 11.

[0113] The protective coating 75 advantageously limits the at least one cooling duct 10 radially on the inside and radially on the outside in the cross section perpendicular to the axial direction A. It is likewise advantageous when said protective coating 75 limits the cooling duct 10 in the circumferential direction U of the stator 2 in the cross section perpendicular to the axial direction A.

[0114] The protective coating 75 can be formed in response to the injection molding of the stator teeth or in response to the injection molding of the stator winding orthis is the case in FIG. 11in a separate method step.

[0115] The space 9 can have the geometry of a trapezoid, preferably of a rectangle, in the cross section perpendicular to the axial direction A.

[0116] The plastic 11, which is injected onto the surface sections 50a, 50b, 50c of the stator teeth 8a, 8b, is formed by means of a first plastic material K1. The plastic 11 embodying the phase insulation 58 is formed by means of a third plastic material K3. The plastic embodying the first and second gap filling 62 is formed by means of a second plastic material K2. The plastic 11 embodying the protective coating 75 is formed by means of the second plastic material K2 or by means of the third plastic material K3.

[0117] The three plastic materials K1, K2, K3 can be identical materials. It is also conceivable, however, that at least two of the three plastic materials K1, K2, K3thus also all three plastic materials K1, K2, K3are different materials. In the example scenario, the first as well as the second and the third plastic material are embodied so as to be electrically insulating. Each of the three plastic materials K1, K2, K3 can generally be a thermoplastic or a thermoset. The three plastic materials K1, K2, K3 can also have identical heat conductivities. Alternatively, at least two of the three plastic materials K1, K2, K3thus also all three plastic materials K1, K2, K3can each have different heat conductivities. The three plastic materials K1, K2, K3 can furthermore be identical materials. Alternatively, at least two of the three plastic materials K1, K2, K3thus also all three plastic materials K1, K2, K3can each be different materials.