LAMINATED CORE AND METHOD FOR PRODUCING A LAMINATED CORE

Abstract

A laminated core (10) is provided for a stator or rotor of an electric machine. The laminated core (10) is formed from multiple laminations (12) that are stacked one on top of another in an axial direction (14) to form a lamination stack (16). A through-opening (18) is formed in the lamination stack (16) and extends parallel to the axial direction (14). A tie rod (20) of plastic is introduced, in particular injection molded, in the through-opening (18) to assemble the laminated core (10).

Claims

1. A laminated core (10) for a stator or rotor of an electric machine, the laminated core (10) comprising: multiple laminations (12) stacked one on top of another in an axial direction (14) to form a lamination stack (16), at least one through-opening (18) extending through the laminations (12) in the lamination stack (16) and aligned parallel to the axial direction (14); and a tie rod (20) of plastic injection molded in the at least one through-opening (18) to assemble the laminated core (10).

2. The laminated core (10) of claim 1, wherein the at least one through opening comprises multiple through-openings (18) formed in the lamination stack (16), each of the through openings (18) extending parallel to the axial direction (14) through the laminations (12), and tie rods (20) of plastic injection molded respectively in the through-openings (18) to assemble the laminated core (10).

3. The laminated core (10) of claim 2, wherein each of the tie rods (20) has opposite axial end portions (30) cross-sectionally widened with respect to the through-opening (18).

4. The laminated core (10) of claim 2, further comprising plastic injection molded around an outer side (23) of the lamination stack (16) to form an outer sheath (34) encapsulating the outer side (23) of the lamination stack (16).

5. The laminated core (10) of claim 4, further comprising plastic injection molded around an inner side (21) of the lamination stack (16) to form an inner sheath (32) encapsulating the inner side (21) of the lamination stack (16).

6. The laminated core (10) as claimed in claim 5, further comprising end disks (36) that cover opposite axial end faces of the lamination stack (16) at least in certain portions, the end disks (36) being connected respectively to at least one of the inner sheath (32) and the outer sheath (34).

7. The laminated core (10) of claim 2, further comprising plastic injection molded around an inner side (21) of the lamination stack (16) to form an inner sheath (32) encapsulating the inner side (21) of the lamination stack (16).

8. A method for producing a laminated core (10) for a stator or rotor of an electric machine, comprising: providing multiple laminations (12); stacking the laminations (12) one on top of another in an axial direction (14) to form a lamination stack (16); assembling the laminations (12) to form a laminated core (10) by a transfer molding process or an injection molding process that includes: introducing a tie rod (20) of plastic into a through-opening (18) formed in the lamination stack (16) and extending parallel to the axial direction (14) through the laminations (12), and at least partially encapsulating the lamination stack (16) by injection molding.

9. The method of claim 8, wherein the laminations have stator teeth (22) on an inner circumferential side of the laminations and stator grooves (24) between the stator teeth (22), the method further comprising introducing one or more groove cores into the stator grooves (24) between the stator teeth (22) on the inner circumferential side (21) of the laminations (12) to align the laminations (12) relative to one another.

10. The method of claim 9, further comprising inserting surface insulation via the groove cores.

11. The method of claim 8, further comprising applying a compressive force in the axial direction (14) to the laminations (12) that are stacked to form a lamination stack (16), the compressive force acting in a ring portion (40) of the laminations (12) that lies on a radially outer edge and/or in a radially inner edge of the laminations (12).

12. The method of claim 11, wherein the compressive force is applied before performing the transfer molding process or the injection molding process

13. A laminated core (10), produced by the method of claim 8.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 a is a plan view of a laminated core and FIG. 1b is a cross section taken along a plane that includes the axis of the laminated core

[0026] FIGS. 2a-d show possible configurations for the encapsulation of the laminated core of FIGS. 1a and 1b by injection molding.

[0027] FIG. 3 is a plan view of the laminated core of FIG. 1a with marked ring portions as possible positions at which a compressive force acts.

DETAILED DESCRIPTION

[0028] FIGS. 1a and 1b illustrate a cut-open side view of a laminated core 10. The example illustrates a laminated core 10 for a stator of an electric machine that is referred to below as “stator laminated core 10”.

[0029] The stator laminated core 10 is formed from multiple laminations 12 that are stacked one on top of another in an axial direction 14 to form a lamination stack 16. In the example, four through-openings 18 are formed in the lamination stack 16 and extend parallel to the axial direction 14 through the laminations 12 or the lamination stack 16, (cf. FIG. 1a). To assemble the stator laminated core 10, a respective tie rod 20 of plastic is introduced, in particular injection molded, in the through-openings 18 (cf. FIG. 1b; for the sake of clarity, only two tie rods 20 are shown).

[0030] The through-openings 18 are distributed uniformly in the circumferential direction of the laminations 12 and are offset in relation to one another by an angle of 90°. Radially inwardly projecting stator teeth 22 are formed on the inner side 21 of the laminations 12, and grooves 24 are between the stator teeth 22. A cross-sectionally widened head 26 is formed on the radially inner end of the stator teeth 22.

[0031] Each tie rod 20 has end portions 30 at each axial end. Each end portion 30 is widened cross-sectionally with respect to the through-opening 18 or that portion 28 of the tie rod 20 that extends in the through-opening 18 (see FIG. 1b).

[0032] FIGS. 2a to 2d illustrate possible configurations for injection molding plastic around the stator laminated core 10.

[0033] FIG. 2a shows a first configuration, in which plastic is injection molded around the lamination stack 16 on the inner side 21. The encapsulation by injection molding forms an inner sheath 32. In addition, plastic is injection molded around the lamination stack 16 on an outer side 23. The encapsulation by injection molding forms an outer sheath 34.

[0034] An end disk 36 is formed at each axial end of the lamination stack 16 and covers the respective end face of the lamination stack 16 at least in certain portions. The end disks 36 are each connected to the inner sheath 32 to provide a virtually complete encapsulation by injection molding, the end disks 36. The outer sheath 34 and the inner sheath 32 are not connected to one another to prevent stress cracks during the demolding (unmolding) operation. The outer sheath 34 and the inner sheath 32 have sleeve-shaped forms and extend in the axial direction 14 (not indicated in FIG. 2 for the sake of clarity). The outer sheath 34 and the inner sheath 32 are concentric to one another.

[0035] FIG. 2b shows a configuration that largely corresponds to the configuration in FIG. 2a, but the end disks 36 are omitted (no end disks are incorporated). The outer sheath 34 and the inner sheath 32 are not connected to one another.

[0036] FIG. 2c shows a configuration that largely corresponds to the configuration in FIG. 2a, but with the outer sheath 34 being omitted. Assembly can take place via the inner sheath 32. The end disks 36 are incorporated in FIG. 2c.

[0037] FIG. 2d shows a configuration similar to FIG. 2a, but with the inner sheath 32 and the outer sheath 34 being connected by the end disks 36.

[0038] FIG. 3 is a plan view of the stator laminated core 10 of FIG. 1a with marked ring portions 40, 42 as possible positions at which a compressive force acts. The method for producing a stator laminated core 10 may proceed as described above. Before or during the assembly, the laminations 12 that are stacked to form a lamination stack 16 may have a compressive force applied to them in the axial direction 14, for example by a corresponding clamping device, as explained above.

[0039] The compressive force may act in a ring portion 40 of the laminations 12 or of the lamination stack 16 that lies on the radially outer edge and/or in a ring portion 42 located at the radially inner end of the stator teeth 22, as explained above.