METHOD FOR PRODUCING A SKEWED STATOR

Abstract

A method for producing a skewed stator having a stator winding composed of shaped conductors includes providing a stator core including a plurality of slots extending from a first end-face to an opposing second end-face and have a skew in the circumferential direction. An arrangement is provided having at least one shaped conductor having two straight leg portions oriented parallel to one another and connected by a connecting portion. Also included is inserting the arrangement into the stator core with the skewed slots at the first end-face by relative movement in the axial direction between the stator core and the arrangement, so that the leg portions of the at least one shaped conductor are bent as a result of the relative movement in such a way that the shape of the leg portions inserted into the stator core acquires a skew which corresponds to the skew of the slots.

Claims

1. A method for producing a skewed stator which has a stator winding composed of shaped conductors, comprising the following steps: providing a stator core which comprises a plurality of slots which extend from a first end face of the stator core to an opposing second end face of the stator core and have a skew in the circumferential direction, providing at least one arrangement having at least one shaped conductor which has two straight leg portions oriented parallel to one another and a connecting portion connecting the two leg portions, inserting the arrangement, of which the shaped conductor comprises the straight leg portions, into the stator core with the skewed slots at the first end face by means of a relative movement in the axial direction between the stator core and the arrangement, so that the leg portions of the at least one shaped conductor are bent as a result of the relative movement in such a way that the shape of the leg portions inserted into the stator core acquires a skew which corresponds to the skew of the slots.

2. The method as claimed in claim 1, wherein the skew of the slots is helical.

3. The method as claimed in claim 1, wherein the arrangement has as much shaped conductors as the leg portions of the shaped conductors, radially layered, fill all slots of the stator core.

4. The method as claimed in claim 1, wherein multiple arrangements are provided which are inserted successively into the stator core, wherein the leg portions of the shaped conductors of the multiple arrangements, radially layered, fill all slots of the stator core.

5. The method as claimed in claim 4, wherein a respective arrangement has as much shaped conductors as the leg portions of the shaped conductors radially layered, fill the slots of the stator core in an angular region in the circumferential direction of maximum 180°, preferably maximum 120°, particularly preferably maximum 90°, and/or radially layered in the slots, fill at most half, preferably at most a third, particularly preferably at most a quarter of the radial extent of a respective slot.

6. The method as claimed in claim 1, wherein before performing the relative movement, a guide tool is arranged on the first end face of the stator core, wherein during performing of the relative movement, a respective leg portion abuts on the guide tool before reaching the slot and is thereby bent so that the skew is formed.

7. The method as claimed in claim 6, wherein for each leg portion, the guide tool has a surface on which the leg portion abuts and is bent tangentially, and/or a surface on which the leg portion abuts and is bent in the radial direction.

8. The method as claimed in claim 6, wherein the guide tool is formed from a plurality of segments, wherein during the bending, the segments are in a radially engaged position on the stator core and are moved radially outward for removal of the guide tool.

9. The method as claimed in claim 1, wherein the stator core is provided with electrically isolating slot liners which are arranged in a respective slot of the stator core, or an electrically isolating slot liner is inserted in the respective slot.

10. The method as claimed in claim 9, wherein the relative movement is performed such that free ends of the leg portions do not touch the slot liners.

11. The method as claimed in claim 2, wherein the arrangement has as much shaped conductors as the leg portions of the shaped conductors, radially layered, fill all slots of the stator core.

12. The method as claimed in claim 2, wherein multiple arrangements are provided which are inserted successively into the stator core, wherein the leg portions of the shaped conductors of the multiple arrangements, radially layered, fill all slots of the stator core.

13. The method as claimed in claim 2, wherein before performing the relative movement, a guide tool is arranged on the first end face of the stator core, wherein during performing of the relative movement, a respective leg portion abuts on the guide tool before reaching the slot and is thereby bent so that the skew is formed.

14. The method as claimed in claim 7, wherein the guide tool is formed from a plurality of segments, wherein during the bending, the segments are in a radially engaged position on the stator core and are moved radially outward for removal of the guide tool.

15. The method as claimed in claim 2, wherein the stator core is provided with electrically isolating slot liners which are arranged in a respective slot of the stator core, or an electrically isolating slot liner is inserted in the respective slot.

16. The method as claimed in claim 3, wherein multiple arrangements are provided which are inserted successively into the stator core, wherein the leg portions of the shaped conductors of the multiple arrangements, radially layered, fill all slots of the stator core.

17. The method as claimed in claim 3, wherein before performing the relative movement, a guide tool is arranged on the first end face of the stator core, wherein during performing of the relative movement, a respective leg portion abuts on the guide tool before reaching the slot and is thereby bent so that the skew is formed.

18. The method as claimed in claim 3, wherein the stator core is provided with electrically isolating slot liners which are arranged in a respective slot of the stator core, or an electrically isolating slot liner is inserted in the respective slot.

19. The method as claimed in claim 4, wherein before performing the relative movement, a guide tool is arranged on the first end face of the stator core, wherein during performing of the relative movement, a respective leg portion abuts on the guide tool before reaching the slot and is thereby bent so that the skew is formed.

20. The method as claimed in claim 4, wherein the stator core is provided with electrically isolating slot liners which are arranged in a respective slot of the stator core, or an electrically isolating slot liner is inserted in the respective slot.

Description

[0038] Further advantages and details of the present invention can be derived from the exemplary embodiments described below and by means of the drawings. The latter are schematic illustrations in which:

[0039] FIG. 1 shows a flowchart for an exemplary embodiment of the inventive method;

[0040] FIG. 2 shows a front view of a stator core used in the method;

[0041] FIG. 3 shows a schematic sketch of a shaped conductor used in the method;

[0042] FIG. 4 shows a schematic sketch of a slot with leg portions of the shaped conductor arranged therein;

[0043] FIG. 5 shows a schematic sketch of a process of inserting an arrangement of shaped conductors in the stator core during the method;

[0044] FIGS. 6 and 7 each show a perspective illustration of a guide tool used during the inventive method; and

[0045] FIG. 8 shows a schematic sketch of an exemplary vehicle with an example of an electrical machine having a stator obtained with the inventive method.

[0046] FIG. 1 is a flow chart of an exemplary embodiment of an inventive method for production of a skewed stator.

[0047] The method comprises a first step S10 in which a stator core 1 is provided, which in particular is configured as a laminated core.

[0048] FIG. 2 is a front view of the stator core 1.

[0049] The stator core 1 in the present case comprises for example 54 slots 2 which extend from a first end face 3 shown in FIG. 2 to an opposite second end face 4 (see FIG. 3). The slots 2 have a helical skew around a slot pitch. Accordingly, an axial opening of a respective slot 2 at the first end face 3 is situated at an angular position in the circumferential direction at which an axial opening of a directly adjacent slot at the second end face 4 is situated (see FIG. 3).

[0050] The step S10 of providing the stator core 1 in this exemplary embodiment comprises five substeps S11 to S15:

[0051] In the first substep S11, a plurality of stator core elements 5 is provided which in particular are each formed as an individual lamination or stator lamination, e.g. with a thickness of 0.27 mm to 0.5 mm, and have passage openings for forming the slots 2. FIG. 2 shows the axially outermost stator core element 5. Typically, the stator core elements 5 are formed by punching. In the next substep S12, the stator core elements 5 are arranged axially layered one upon the other, so that the passage openings of the stator core elements 5 extend straight in the axial direction. In the next substep S13, the skew of the stator core 1 is created in that the passage openings are collectively offset to one another. For this, an offset tool extending along all layered stator core elements 5 is inserted radially from the inside into one or more slots 2 and pivoted to create the skew. In the next substep S14, the stator core elements 5 are joined together so that they are connected together rotationally fixedly. For this, several axial weld seams are created on the outside of the stator core 1 thus provided. This is done preferably by laser welding. In substep S15, an electrically isolating slot liner 6 (see FIG. 4) of insulating paper is inserted in each slot 2 and extends completely between the end faces 3, 4 in the axial direction and fully lines the slot 2 in the circumferential direction.

[0052] According to an alternative exemplary embodiment, step S13 is omitted if the stator core elements 5 are already axially layered with the offset to one another forming the skew.

[0053] FIG. 3 shows a schematic sketch of a shaped conductor 7 used in the method.

[0054] FIG. 4 shows a schematic sketch of a slot 2 with shaped conductors 7 received therein.

[0055] The shaped conductor 7 comprises two straight leg portions 8, which extend equidistantly, and a connecting portion 9, which connects the leg portions 7 electrically conductively. The connecting portion 8 is configured such that when the leg portions 7 are inserted in the slots 2, they are arranged in different slots 2 and in different radial layers within a respective slot 2, in particular by form fit. FIG. 4 shows that eight leg portions 8 in eight layers of a slot 2, which is lined by the slot liner 6, fill around 80% of the cross-sectional area of the slot 2. As shown, the leg portions 8 have a rounded rectangular cross-section. Each shaped conductor 7 is made of copper, wherein the leg portions 8 are formed integrally with the connecting portion 9.

[0056] FIG. 5 shows a schematic sketch of a process of inserting an arrangement 10 of shaped conductors 7 into the stator core 1 during the method.

[0057] In a step S20 of the method, the arrangement 10 is provided from a plurality of shaped conductors 7, wherein the leg portions are straight and oriented parallel to one another. The step S20 in this exemplary embodiment comprises three substeps S21 to S23:

[0058] In substep S21, a rod of copper is provided. In substep S22, this is bent so as to form firstly the connecting portion 9 and secondly the leg portions 8, which run straight and parallel to one another. The connecting portions 9 are bent such that the leg portions 8 of the shaped conductor 7 achieve an offset by several slots in the circumferential direction and an offset by one or more layers in the radial direction. The connecting portion 9 is formed by rotary draw bending, for example by means of a 3D bending device.

[0059] In substep S23, sufficient shaped conductors 7 for the arrangement 10 in the form of a shaped conductor basket are arranged so that the leg portions of the shaped conductors, radially layered, completely or almost completely fill all slots 2 of the stator core 1. In the arrangement 10, all connecting portions 9 lie at one axial end of the arrangement 10, and all free ends of the leg portions 8 lie at the other axial end of the arrangement 10.

[0060] FIGS. 6 and 7 each show a perspective illustration of a guide tool 11 used in the inventive method. The guide tool 11 is formed from a plurality of segments 11a, which correspond in number to half the number of slots 2 of the stator core 1. The segments 11a are in an engaged position in FIG. 6 and in a released position in FIG. 7. Each segment 11a has two radial protrusions 11b. In the present exemplary embodiment, the guide tool 11 is made for example of steel and has a higher mechanical strength than the shaped conductors 7.

[0061] In a step S30, the guide tool 11 is arranged on the first end face 3 of the stator core 1. For this, the segments 11a are arranged in their engaged position on the stator core 1 such that every second slot 2 sits between the protrusions 11b of a respective segment 11a and the other slots 2 between the protrusions 11b of two adjacent segments 11a. The guide tool 11 or a respective segment 11a here fixes the slot liners 6.

[0062] As FIG. 5 shows, in a step S40, a relative movement is performed in the axial direction between the stator core 1 and the arrangement 10. Only a linear movement in the axial direction of the arrangement 10 is performed, wherein the stator core 1 remains unmoved. The relative movement causes the insertion of the shaped conductors 7 into the slots 2. A respective leg portion 8 here abuts on a surface 12 (see FIG. 7) of the guide tool 11 and is bent tangentially. A respective surface 12 slopes more steeply relative to the centre axis of the stator core 1 than the skew angle of the slots 2, so the leg portions 8 can spring back after bending. The surfaces 12 are also formed smoother than the surfaces of the stator core 1 inside the slots 2, so that the leg portions 8 can slide easily over the surfaces 12. In some cases, the relative movement in the axial direction may be overlaid by a relative movement in the circumferential direction.

[0063] The relative movement is performed until the free ends of the leg portions 8 on the second end face 4 protrude out of the stator core 1. The relative movement takes place such that the free ends of the leg portions 8 do not touch the slot liners 6, in order to avoid damaging the slot liners 6. For this, as described above, the slot liners 6 are fixed by the guide tool 11. Also, the surface 12 is axially further out than the slot liners 6.

[0064] In further exemplary embodiments, it is possible that during the relative movement, the arrangement 10 remains unmoved and the stator core 1 is moved in the axial direction. It is furthermore possible that during the relative movement, both the arrangement 10 and also the stator core 1 are moved.

[0065] In a next step S50, the guide tool 11 is removed from the stator core 1. For this, as shown in FIG. 7, the segments 11a are moved radially outward.

[0066] In a next step S60, the free ends of the leg portions 8 at the second end face 4 are bent so that the free ends of two different leg portions lie against one another. In a next step S70, the free ends lying against one another are connected together electrically conductively by substance bonding by means of laser welding.

[0067] According to an alternative exemplary embodiment, in step S20, multiple arrangements 10 are provided or arranged in substep 23 as shaped conductor part baskets. A respective arrangement 10 here comprises sufficient shaped conductors 7 for their leg portions, radially layered, to fill slots 2 of the stator core 1 in a predefined angular region in the circumferential direction of maximum stator core elements 90° and/or, radially layered in the slots 2, to fill a quarter of the radial extent of a respective slot 2. These arrangements 10 are inserted successively in the slots 2 in step S40.

[0068] FIG. 8 shows a schematic sketch of a vehicle 100 with an electrical machine 101, which has a stator 103, produced using the above-described method.

[0069] An unskewed rotor 102 is mounted rotatably relative to the stator 103 inside the stator 103 of the electrical machine 101, which in the present case is configured as a permanently excited synchronous motor. It is evident that only connecting portions 9 of the shaped conductors 7 are situated on the first end face 3 of the stator core 1, and only the welded free ends of the leg portions 8 of the shaped conductors 7 are situated on the second end face 4 of the stator core 1.

[0070] The electrical machine 101 is designed to drive the vehicle 100. This is configured as a partly or fully electrically driven vehicle, for example a battery electric vehicle (BEV) or as a hybrid vehicle.