METHOD FOR PRODUCING A STATOR FOR AN ELECTRIC MACHINE

Abstract

A method for producing a stator for an electric machine includes providing a stator with an annular stator body, from which a plurality of stator teeth protrude radially inwardly, wherein an intermediate space is formed in each case between two stator teeth that are adjacent in a circumferential direction, encapsulating two stator teeth adjacent in the circumferential direction with a first plastic mass, arranging a stator winding on a stator tooth, fixing the stator winding on the stator tooth by encapsulating said stator winding with a second plastic mass, following the encapsulation with the first plastic mass and before the fixing of the stator winding, a first mask is introduced into the intermediate space between the two stator teeth, such that the volume of the intermediate space that is filled with the first mask remains free from the second plastic mass to form a cooling duct during the encapsulation.

Claims

1. A method for producing a stator for an electric machine, the method comprising: (a) providing a stator, which comprises an annular stator body, from which multiple stator teeth for receiving stator windings that are arranged spaced from one another along a circumferential direction of the stator body protrude radially to the inside, wherein between two stator teeth adjacent in the circumferential direction, an intermediate space is formed in each case; (b) at least partial overmolding at least two stator teeth that are adjacent in the circumferential direction with a first plastic mass; (c) arranging at least one stator winding on at least one stator tooth; (d) fixing the at least one stator winding on the at least one stator tooth through at least partial overmolding of this stator winding with a second plastic mass; and following the overmolding with the first plastic mass according to step (b) and prior to the fixing of the at least one stator winding according to step (d), introducing a first mask into the intermediate space between the two stator teeth, such that the volume of the intermediate space filled out by the first mask for forming a cooling passage remains free of the second plastic mass during the overmolding according to step (d).

2. The method according to claim 1, wherein the first mask covers a surface portion of the stator body bounding the intermediate space radially outside, which can have been partly or completely covered with the first plastic mass in step (b), such that the surface portion during the overmolding according to step (d) is not covered with the second plastic mass.

3. The method according to claim 1, further comprising: introducing the first mask into a radially outer end portion of the intermediate space.

4. The method according to claim 3, wherein the first mask completely fills out the radially outer end portion.

5. The method according to claim 1, further comprising: (e) removing the first mask from the intermediate space following the overmolding with the second plastic mass, such that a hollow space that is present following the removing of the first mask forms a coolant passage for a coolant to flow through.

6. The method according to claim 1, further comprising: (f) overmolding of the second plastic mass bounding the hollow space or the coolant passage and/or of the stator winding fixed to the stator tooth with the second plastic mass and/or of the surface portion of the stator body covered by the first mask prior to the removal of the same with a third plastic mass.

7. The method according to claim 6, further comprising: carrying out the overmolding with the third plastic mass after the removing of the first mask.

8. The method according to claim 6, wherein the coolant passage is bounded by the first and/or the third plastic mass.

9. The method according to claim 1, further comprising: following the overmolding with the first plastic mass according to step (b) and prior to the fixing of the at least one stator winding according to step (d), introducing a second mask in a radially inner end portion of the intermediate space, such that the volume of the intermediate space filled out by the second mask, remains free of the second plastic mass during the overmolding according to step (d) for forming an additional cooling passage.

10. The method according to claim 9, wherein the second mask covers a surface portion of the stator teeth bounding the intermediate space radially inside, which can have been partly or completely covered with the first plastic mass in step (b), such that the surface portion in step (d) is not covered with the second plastic mass.

11. The method according to claim 9, further comprising: (e1) removing the second mask from the intermediate space after the overmolding with the second plastic mass, such that a hollow space that is present following the removing of the second mask, forms an additional coolant passage for a coolant to flow through.

12. The method according to any claim 6, further comprising: carrying out the overmolding with the third plastic mass such that following the overmolding the overmolded hollow space and/or additional hollow space or coolant passage and/or additional coolant passage is not directly bounded by the stator winding and/or by the stator body at any point.

13. The method according to claim 1, further comprising: (g) overmolding at least one outer circumferential side of the stator body with a fourth plastic mass.

14. The method according to claim 1, wherein the first and/or the second and/or the third and/or the fourth plastic mass comprises/comprise a thermosetting plastic or is/are a thermosetting plastic.

15. The method according to claim 1, wherein the first and/or the second and/or the third and/or the fourth plastic mass comprises a thermoplastic or is a thermoplastic.

16. The method according to claim 1, wherein: the plastic material of the first, second, and third plastic mass comprises the same thermosetting plastic or consists of the same thermosetting plastic, and the plastic material of the fourth plastic mass is a thermoplastic that is distinct from the thermosetting plastic of the first, second, and third plastic mass.

17. The method according to claim 16, wherein the heat conductivity of the fourth plastic mass is lower than the heat conductivity of the first and/or second and/or third plastic mass, and/or in that the strength of the fourth plastic mass is higher than the strength of the first and/or second and/or third plastic mass.

18. The method according to claim 1, wherein: the plastic material of the first and of the third plastic mass comprises the same thermosetting plastic or consists of the same thermosetting plastic and is distinct from the plastic material of the second and the fourth plastic mass, and the plastic material of the second plastic mass is distinct from the plastic material of the fourth plastic mass.

19. The method according to claim 18, wherein: a coolant resistance of the first and/or third plastic mass is higher than the coolant resistance of the second and/or fourth plastic mass, and/or the heat conductivity of the first and/or of the third plastic mass is lower than the heat conductivity of the second plastic mass, and/or the strength of the fourth plastic mass is higher than the strength of the first and/or the second and/or the third plastic mass.

20. The method according to claim 18, wherein a layer thickness of the third and/or first plastic mass bounding the respective cooling passage amounts to a maximum of 0.8 mm, or a maximum of 0.3 mm.

21. The method according to claim 1, wherein the plastic materials of the first, second, third, and fourth plastic mass comprise different thermoplastics or thermosetting plastics or consist of different thermoplastics or thermosetting plastics.

22. The method according to claim 21, wherein: a coolant resistance of the first and/or third plastic mass is higher than a coolant resistance of the second plastic mass, and/or the heat conductivity of the second plastic mass is higher than the heat conductivity of the first and/or third and/or fourth plastic mass, and/or the strength of the fourth plastic mass is higher than the strength of the first and/or second and/or third plastic mass.

23. The method according to claim 1, wherein the method further comprises: (h1) providing a coolant distribution space and a coolant collector space on and/or in the stator, which via the at least one coolant passage and/or via the at least one additional coolant passage fluidically communicate with one another; and (h2) overmolding and/or spraying of the second plastic mass bounding the coolant distribution space and/or the coolant collection space and/or the axial end portions of at least one stator winding, or of all stator windings, with an electrically insulating insulation material, or an electrically insulating varnish, and/or with the third plastic mass and/or with the fourth plastic mass.

24. The method according to claim 23, wherein the overmolding or spraying according to step (h2) is carried out in such a manner that following the overmolding or spraying, neither the second plastic mass nor the axial end portions of the at least one stator winding, or of stator windings, bound the coolant distribution space or the coolant collection space.

25. The method according to claim 23, wherein in step (d), the axial end portions of the at least one stator winding are also fixed to the at least one stator tooth with the second plastic mass.

26. A stator produced with the method according to claim 1.

27. An electric machine comprising: the stator produced with the method according to claim 1; and the rotor configured to be rotatable about an axis of rotation relative to the stator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The disclosure will now be described with reference to the drawings wherein:

[0061] FIGS. 1A and 1B show a stator provided in step a) of the method in different representations,

[0062] FIGS. 2A, 2B, and 2C show the stator shown in FIGS. 1A and 1B following the carrying out of step b) in different representations,

[0063] FIGS. 3A, 3B, and 3C show the stator shown in FIGS. 2A, 2B, and 2C following the carrying out of step c) in different representations,

[0064] FIGS. 4A, 4B, and 4C show the stator shown in FIGS. 2A, 2B, and 2C following the carrying out of step d) in different representations,

[0065] FIGS. 5A, 5B, and 5C show the stator shown in FIGS. 2A, 2B, and 2C following the carrying out of step e) in different representations,

[0066] FIGS. 6A and 6B show the stator shown in FIGS. 2A, 2B, and 2C following the carrying out of step e) in different representations, and

[0067] FIGS. 7A and 7B show two versions that are alternative to one another illustrating the method step h).

DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0068] FIG. 1A illustrates in perspective representation a stator 1 with an annular stator body 2, provided in step a) of the method according to an aspect of the disclosure. As is evident from FIG. 1A, multiple stator teeth 3 for receiving stator windings (not shown in FIG. 1) which are arranged spaced from one another along a circumferential direction U of the annular stator body 2 protrude from the stator body 2 radially to the inside.

[0069] Between two stator teeth 3 that are adjacent in the circumferential direction U, an intermediate space 4 is formed in each case, which is also familiar to a person skilled in the art under the term stator slot. FIG. 1B shows a detail representation of the stator body 2 of FIG. 1A in a detailed representation in the region of two stator teeth 3 that are adjacent in the circumferential direction U and in a plan view along an axial direction A, which extends along a center longitudinal axis M of the stator body 2 and thus runs perpendicularly to the circumferential direction U. A radial direction R extends perpendicularly away from the center longitudinal axis and thus runs orthogonally both to the axial direction A and also to the circumferential direction U.

[0070] At an end portion facing away from the stator body 2, each stator tooth 3 can include an extension 12a and 12b protruding from the stator tooth 3 in the circumferential direction U and also against the circumferential direction U, such that in each case two extensions 12a and 12b located opposite one another in the circumferential direction U of two stator teeth 3 adjacent in the circumferential direction U partly bound the intermediate space 4 while forming a passage slot 13 radially inside.

[0071] In a further method step b), the stator teeth 3 are overmolded with a first plastic mass K1. FIGS. 2A and 2B show the stator body 2 following the carrying out of the method step b) in a representation corresponding to the FIGS. 1A and 1B. For illustration, FIG. 2C shows a detailed representation of FIG. 2A, multiple adjacent stator teeth 3.

[0072] Following the overmolding with the first plastic mass K1 according to step b) and prior to fixing of the stator windings 5 according to step d), a first mask 6a is introduced in each case between the two stator teeth 3 into a radially outer end portion 10a of the intermediate spaces 4. Typically, the first mask 6a completely fills out the radially outer end portion 10a. Thus, the volume of the intermediate space 4 filled out by the first mask 6a for forming a cooling passage 9 remains free of this second plastic mass K2 in the step d) still to be carried out later on, i.e., during the overmolding with the second plastic mass K2.

[0073] Practically, the first mask 6a can cover a surface portion 7 of the stator body 2 bounding the intermediate space 4 radially outside, which in step b) can have been partly or completely covered with the first plastic mass K1. In this way it is prevented that the surface portion, in the method step d) still to be carried out later on, is covered with the second plastic mass K2.

[0074] In a further method step c), stator windings 5 are arranged on the stator teeth 3. This is rough-schematically shown in the FIGS. 3A, 3B, and 3C, which show the stator body 2 following the carrying out of the method step c) in a representation corresponding to the FIGS. 2A, 2B, and 2C.

[0075] In a further method step d), the stator windings 5 are fixed to the stator teeth 3 through at least partial overmolding with a second plastic mass K2. This is rough-schematically shown in the FIGS. 4A, 4B, and 4C, which shows the stator body 2 in a representation corresponding to the FIGS. 3A, 3B, and 3C. The volume filled out by the first masks 6a remains, as explained above, free of second plastic mass K2. The first masks 6a cover a surface portion 7 of the stator body 2 which bounds the intermediate space 4 radially outside, which in step b) can have already been partly or completely covered with the first plastic mass K1. In this way it is prevented that the surface portion 7, in the step d) still to be carried out later on, is covered with the second plastic mass K2. Following the overmolding with the second plastic mass K2, the first masks 6a are again removed from the intermediate spaces 4 in a method step e), so that following the removal of the masks 6a a hollow space 8 that is present in each case can form a coolant passage 9 for coolant to flow through.

[0076] Optionally, following the overmolding with the first plastic mass K1 according to step b) and prior to the fixing of the stator windings 5 according to step d), a second mask 6b can also be introduced into a radially inner end portion 10b of the respective intermediate space 4. Thus, the volume of the intermediate space 4 filled out by the second mask 6b for forming an additional cooling passage 9 during the overmolding according to step d) remains free of the second plastic mass K2. Analogously to the first masks 6a, the second masks 6b can each cover a surface portion 7 of the two stator teeth 3 bounding the intermediate space 4 radially inside which in step b) can already have been partly or completely covered with the first plastic mass K1. Thus, it is prevented that the surface portion 7 in step d) is not covered with the second plastic mass K2.

[0077] Analogously to the first masks 6a, the second masks 6b, following the overmolding with the second plastic mask K2, can be again removed from the passage slots 13, such that hollow spaces 8 formed after the removal of the respective second mask 6b each form an additional coolant passage 9 for coolant to flow through.

[0078] In a further method step f), the second plastic mass K2 bounding the hollow space 8 or coolant passage 9, the stator windings 3 fixed to the stator teeth 2 with the second plastic mass K2 and the surface portions 7 of the stator body 2 covered by these prior to the removal of the first masks 6a are overmolded with a third plastic mass K3. Step f) is carried out after the removal of the first masks 6a. Typically, the overmolding with the third plastic mass K3 as part of step f) is carried out in such a manner that the hollow spaces 8 or coolant passages 9 after the overmolding with the third plastic mass K3 are exclusively bounded by the third or first plastic mass K3 and K1.

[0079] In this case, formed hollow spaces 8 or coolant passages 9 are exclusively bounded by the first or third plastic mass K1 and K3, such that the desired electrical insulation of the stator body 2 relative to the coolant flowing through the coolant passages 9 is ensured. It is possible, in particular, that the additional coolant passages 9 are exclusively bounded by the third and the first plastic mass K3 and K1.

[0080] During the course of the production method explained here, the second plastic mass K2 bounding the additional coolant passages 9, the stator windings 5 fixed to the stator teeth 3 with the second plastic mass K2 and the surface portions 7 of the stator teeth 3 covered by the second masks 6b prior to the removal of the same, can be overmolded with a third plastic mass K3. Here, the overmolding is carried out in such a manner that the additional coolant passages 9, after the overmolding with the third plastic mass K3, are exclusively bounded by the third and the first plastic mass K3 and K1.

[0081] Analogously to the coolant passages 9, the additional coolant passages 9 are also exclusively bounded by the first or third plastic mass K3. It is possible, in particular, that the additional coolant passages 9 are exclusively bounded by the third plastic mass K3.

[0082] In other words, the overmolding with the third plastic mass K3 is particularly practically carried out in such a manner that following the overmolding, the hollow spaces 8 and 8 or the coolant passages 9 and 9 are not directly bounded by the stator windings or by the stator body 2 at any point. In a further method step, at least one outer circumferential side 16 of the stator body 2 can be overmolded with a fourth plastic mass K4. This is shown in the FIGS. 6A and 6B, the representations of which correspond to the FIGS. 5A and 5B. During the course of the overmolding with the fourth plastic mass K4, axially extending extensions 18 provided on the outer circumferential side 16 of the stator body 2 as indicated in the FIGS. 6A and 6B, from which axially on the end side in each case threaded rods 19 for fastening a respective bearing shield to the stator body 2 protrude, can likewise be overmolded with the fourth plastic mass K4.

[0083] In a further optional method step, two bearing shields can be fastened to the stator body along the axial direction A located opposite with the overmolded threaded rods 19. This is shown for two versions that are alternative to one another in the FIGS. 7A and 7B. In both versions, a first bearing shield 20a thus seals a first hollow space 21 provided in the third and fourth plastic mass K3 and K4, which forms a coolant distributor 22a and for this purpose fluidically communicates with the cooling passages 9 and 9 that are present in the stator 1. A second bearing shield (not shown) seals a second hollow space (not shown) formed in the third and fourth plastic mass K3 and K4, which forms a coolant collector (not shown) and for this purpose fluidically communicates with the cooling passages 9 and 9 formed in the stator 1. The two bearing shields according to FIGS. 7A and 7B lie opposite one another along the axial direction A and axially bound the stator body 2 of the stator 1.

[0084] In the longitudinal section of the stator 1 along the axial direction A according to FIG. 7A, the coolant distributor 22a and the coolant collector each have a U-shaped geometry which partly surround a respective axial end portion 23 of the stator windings 5 in the axial extension and radially outside and radially inside. In the longitudinal section of the stator 1 along the axial direction A according to FIG. 7, the coolant distributor 22a and the coolant collector each have an I-shaped geometry, which partly surround a respective axial end portion of the stator windings 5 in the axial extension and radially outside. The fastening of the bearing shields 28 to the stator body 2 is carried out with the already mentioned threaded rods 19 provided on the stator body 2 together with threaded nuts 24 matched to these threaded rods 19. The first and the second masks 6a and 6b can each be formed as an insert 17a and 17b formed plate-like or platelet-like, or of a steel.

[0085] In a first version of the example, the plastic material of the first and second and third plastic mass K1, K2, and K3 include thermosetting plastics or consist of the same thermosetting plastics. Compared with this, the plastic material of the fourth plastic mass K4 is a thermoplastic that is distinct from the thermosetting plastics of the first, second and third plastic mass. The heat conductivity of the fourth plastic mass K4 in this version is lower than the heat conductivity of the first, second, and third plastic mass K1, K2, and K3. Apart from this, the strength of the fourth plastic mass K4 in this exemplary embodiment is higher than the strength of the first, second, and third plastic mass K1, K2, and K3.

[0086] In a second version of the example, the plastic material of the first and of the third plastic mass K1 and K3 includes the same thermosetting plastic or consists of the same thermosetting plastic, whereas it is distinct from the plastic material of the second and of the fourth plastic mass K2 and K4. In this version, the plastic material of the second plastic mass K2 is distinct from the plastic material of the fourth plastic mass K4. In this version, a coolant resistance of the first and third plastic mass K1 and K3 is greater in each case than a coolant resistance of the second plastic mass K2. Furthermore, the heat conductivity in this version of the first and third plastic mass K1 and K3 is lower in each case than the heat conductivity of the second plastic mass K2. Finally, alternatively or additionally, the strength of the fourth plastic mass K4 in this version of the example is higher than the strength of the first, second, and third plastic mass K1, K2, and K3. A layer thickness of the third and first plastic mass K3 and K1 in this version of the example amounts to a maximum of 0.8 mm, typically a maximum of 0.3 mm.

[0087] In this version, a coolant resistance of the first and third plastic mass K1 and K3 is higher in each case than a coolant resistance of the second and the third plastic mass K2 and K4. Apart from this, the heat conductivity of the second plastic mass K2 in this further development is higher than the heat conductivity of the first, third and/or fourth plastic mass K1, K3, and K4. Alternatively or additionally, the strength of the fourth plastic mass K4 in this further development is higher than the strength of the first and/or second and/or third plastic mass K1, K2, and K3.

[0088] According to an optional method step, the second plastic mass K2 initially bounding the coolant distribution space 22a and the coolant collector space 22b can be overmolded and/or sprayed with an electrically insulating insulation material. Likewise, axial end portions of the stator windings 6, which can protrude on both sides from the respective intermediate space 4 along the axial direction A, can be overmolded and/or sprayed with the electrically insulating insulation material. Practically, an electrically insulating varnish is used for this purpose. However, it is also conceivable to use the third plastic mass K3 and/or the fourth plastic mass K4 or another suitable plastic mass. The overmolding, spraying is carried out in such a manner that following the overmolding or spraying, neither the second plastic mass K2 nor the axial end portions of the stator windings 5 directly bound the coolant distribution space 22a or the coolant collector space 22b. In this way, an undesirable electrical connection of the electrically conductive stator windings 6 with the coolant that is present in the coolant distribution space 22 or coolant collection space 22b is excluded.

[0089] During the course of step d) or offset in time thereto, i.e., prior to the carrying out of step d) or after the carrying out of step d), the axial end portions of the stator windings 5 can also be fixed to the respective stator tooth 3 with a plastic mass, in particular with the second plastic mass K2.

[0090] It is understood that the foregoing description is that of the exemplary embodiments of the disclosure and that various changes and modifications may be made thereto without departing from the spirit and scope of the disclosure as defined in the appended claims.