Method for producing a stator of an electric machine

Abstract

The invention relates to a method for producing a stator (1) of an electric machine (2), the method comprising the following step: c. using a shaping device (12) to shape the conductor ends (6e) of the unconnected winding head (10) in the circumferential direction so as to form joining pairs (16) of opposing conductor ends (6e) that are to be interconnected, characterized in that the shaping of the conductor ends (6e) according to step c) comprises the following steps: i. using at least one bending tool (13) of a first shaping device (12.1) to pre-bend the conductor ends (6e) of the winding head layers (11), wherein the bending tool (13), in order to pre-bend the conductor ends (6e) of an individual winding head layer (11), is immersed into a clearance (14) of the respective winding head layer (11) to a penetration depth (T) and moved on a tool circular path (15) corresponding to the respective winding head layer (11), and in the process, with the tool section immersed, bends the conductor ends (6e) of the winding head layer (11) individually and successively in the circumferential direction, ii. completing the bending of the pre-bent conductor ends (6e) of the unconnected winding head (10) by axially pressing a shaping die (20) of a second shaping device (12.2) onto the unconnected winding head (10), so as to reduce a winding head height (10h) of the unconnected winding head (10).

Description

[0001] Description

[0002] title

[0003] Method for manufacturing a stator of an electrical machine

[0004] State of the art

[0005] The invention relates to a method for manufacturing a stator of an electrical machine according to the preamble of the main claim.

[0006] A method for manufacturing a stator of an electric machine is already known from DE102019131995 A1, wherein the method comprises the following steps: in a first step, a stator body comprising stator slots, in particular a stator laminate pack, is provided. In a second step, conductor elements, in particular hairpins or I-pins, of a stator winding to be manufactured are inserted into the stator slots, forming at least one unconnected winding head, the unconnected conductor ends of which are arranged in annular winding head layers. In a third step, the conductor ends of the unconnected winding head are formed circumferentially by a forming device, which is a so-called twisting or forming device for forming the unconnected winding head, such that joining pairs of opposing conductor ends to be electrically connected are formed.In a fourth step, in particular, stripped conductor ends are joined together to form the stator winding, especially by welding.

[0007] A disadvantage is that conventional forming devices for forming an unconnected winding head are very expensive and require complex and costly adaptation to manufacture different stators with different stator windings. Consequently, the stator manufacturing process using such a conventional forming device is also very expensive and inflexible. Advantages of the invention

[0008] The inventive method for manufacturing a stator of an electric machine with the characterizing features of the main claim has the advantage that it can be carried out with two very simple, uncomplicated, and therefore robust forming devices for forming the respective winding head. In contrast to the prior art, the two forming devices according to the invention can be used to manufacture different stators with little or no tooling adjustment. This results in very low acquisition and conversion costs for both forming devices according to the invention. The conversion time for the two forming devices according to the invention is shorter than the conversion time required for the conventional forming device from the prior art.

[0009] Furthermore, the inventive method can be used to produce a winding head that is particularly short in the axial direction of a stator axis.

[0010] This is achieved according to the invention by forming the conductor ends according to step c) comprising the following steps: i. Pre-bending the conductor ends of the winding head layers with at least one bending tool of a first forming device, wherein the bending tool for pre-bending the conductor ends of a single winding head layer is immersed with a penetration depth into a free space of the respective winding head layer and moved on a tool circular path corresponding to the respective winding head layer, thereby bending the conductor ends of the winding head layer individually and successively in the circumferential direction with the immersed tool section, ii. Finish-bending the pre-bent conductor ends of the unconnected winding head by axially pressing a forming punch of a second forming device onto the unconnected winding head, thereby reducing a winding head height of the unconnected winding head.

[0011] After pre-bending all conductor ends of all winding head layers of the respective winding head in step c) i.), a pre-bent winding head is formed, which can then be fully formed by the forming punch. To complete the bending of the conductor ends, the forming punch presses all pre-bent conductor ends of all winding head layers of the respective winding head simultaneously in the axial direction. The winding head, now fully formed, is thus produced in two successive steps c) i) and c) ii) using the different tools of the two forming devices.

[0012] The measures listed in the dependent claims enable advantageous further developments and improvements of the method specified in the main claim.

[0013] In step c) i.) the bending tool encounters the individual conductor ends of the respective winding head layer along the movement on the tool's circular path, whereby the respective conductor end is pushed away by the bending tool in the direction of the movement of the bending tool and towards the stator body, forming a pre-bend, until the bending tool can pass the respective conductor end.

[0014] It is advantageous if the winding head layers are pre-bent individually, one after the other, layer by layer, using the bending tool in step c) i.) . This enables a very simple, uncomplicated and therefore robust first forming device for pre-bending the conductor ends of the respective winding head.

[0015] It is particularly advantageous if the penetration depth of the bending tool is selected such that the conductor ends are pre-bent by one to two stator slots in step c) i.). This achieves a degree of pre-bending of the conductor ends that allows the use of the forming punch for step c) ii.).

[0016] It is further advantageous if, in step c) i.), the bending tool makes at least one revolution, and in particular several revolutions, on the respective tool circular path for each winding head layer. In this way, sufficient pre-bending of all conductor ends of all winding head layers of the respective winding head can be achieved, so that the final bending of the conductor ends in step c) ii.) can be carried out with the forming punch. It is very advantageous if the penetration depth of the bending tool in step c) i.) is increased after at least one revolution to further pre-bend the conductor ends. By gradually increasing the penetration depth, the pre-bending of all conductor ends of a winding head layer can be progressively increased per revolution until sufficient pre-bending is achieved.

[0017] After an initial winding of the stator, in steps c) i.) and / or c) ii.), the winding head layers in the unconnected winding head can be supported individually or in pairs in a radial direction with respect to a stator axis, particularly on both sides. When winding head layers are supported in pairs, two adjacent winding head layers are supported. In this way, the conductor ends of the respective winding head layer cannot deflect radially during the respective forming process (pre-bending, final bending), thus ensuring the desired forming of the conductor ends.

[0018] After a second winding of the stator, in steps c) i.) and / or c) ii.), the outermost and / or innermost winding head layer in the unconnected winding head can be supported radially with respect to a stator axis. This prevents the conductor ends of the respective winding head layer from deflecting radially during the respective forming process (pre-bending, final bending), thus ensuring the desired forming of the conductor ends.

[0019] Furthermore, it is advantageous if the conductor ends of a joining pair cross after step c) i.) and after step c) ii.). In this way, a winding head that is short in the axial direction with respect to the stator axis is achieved.

[0020] Furthermore, it is advantageous if, after step c) ii.), the conductor ends of the winding head each have a bending radius at the exit from the stator body, generated by the bending process, which is particularly in the range of 20-30 mm, wherein the ratio of the stator outer diameter to the bending radius is particularly in the range of 5 to 10. The method according to the invention produces a bending radius that differs from the prior art. It is advantageous if the bending tool of the first forming device is provided as a projection, in particular as a tooth, point, or bending finger, especially in a triangular shape, on a rotary device rotatable about a stator axis, in particular a rotary shaft, a rotary table, or a robot arm. In this way, the movement of the bending tool on the tool's circular path can be achieved with simple means. The costs of the first forming device are therefore comparatively low.

[0021] Furthermore, it is advantageous if at least one bending tool of the rotary device is radially adjustable to adapt the circular path to the respective winding head layer to be pre-bent. In this way, all winding head layers of the respective winding head can be pre-bent with the same bending tool. The first forming device is therefore very flexible and can be used to manufacture different stators, for example, when changing the number of winding head layers of the respective winding head and / or changing the radial position of the winding head layers of the respective winding head.

[0022] drawing

[0023] Exemplary embodiments of the invention are shown in simplified form in the drawing and explained in more detail in the following description.

[0024] They show:

[0025] Fig. 1 shows a partial view of an unconnected winding head of a stator of an electric machine and a rotatable bending tool of a first forming device for pre-bending the conductor ends of a single winding head layer of the winding head; Fig. 2 shows a top view of the unconnected winding head and the bending tool according to Fig. 1; Fig. 3A shows a first step of a method according to the invention for manufacturing a stator of an electric machine; Fig. 3B shows a second step of the method according to the invention; Fig. 4 shows several partial steps according to Figs. 4A-4F for pre-bending the conductor ends of a first winding head layer of the respective winding head in a circumferential direction; Fig. 5 shows several partial steps according to Figs. 5A-5F for pre-bending the conductor ends of a second winding head layer of the respective winding head in an opposite circumferential direction.

[0026] Fig. 6 shows the unconnected winding head after pre-bending the conductor ends of all winding head layers according to the invention, as well as a forming die of a second forming device for finishing the unconnected winding head; Fig. 7 shows the finished winding head after application of the forming die according to Fig. 6.

[0027] Fig. 8 shows the welding of conductor ends of the winding head to form the stator winding.

[0028] Description of the exemplary implementations

[0029] Fig. 1 shows a partial view of an unconnected winding head of a stator of an electrical machine and a rotatable bending tool of a first forming device for pre-bending the conductor ends of a single winding head layer of the winding head.

[0030] The inventive method for manufacturing a stator 1 of an electrical machine 2 comprises first a step a) of providing a stator body 3, in particular a stator laminate pack, with stator slots 4 (Fig. 3A) and a step b) of inserting conductor elements 6, in particular hairpins or I-pins, of a stator winding 7 to be manufactured into the stator slots 4 of the stator body 3 (Fig. 3B).

[0031] After the conductor elements 6 are inserted into the stator slots 4, at least one unconnected winding head 10 protruding from the stator body 3 is formed according to Fig. 1, the unconnected conductor ends 6e of which are arranged in annular winding head layers 11. Fig. 2 shows a top view of the unconnected winding head and the bending tool according to Fig. 1.

[0032] Furthermore, the inventive method comprises a step c) of forming the conductor ends 6e of the unconnected winding head 10 with a forming device 12 in the circumferential direction with respect to a stator axis 5 such that joining pairs 16 of opposing conductor ends 6e to be connected are formed.

[0033] To form the stator winding 7, a portion of the winding head layers 11 must be pre-bent in one circumferential direction, and the other portion must be pre-bent in the opposite circumferential direction. Figures 4A-4F therefore show the pre-bend of the conductor ends 6e in a first winding head layer 11.1 of the respective winding head 10 in one circumferential direction. Figures 5A-5F also show the pre-bend of the conductor ends 6e of a second winding head layer 11.2 of the respective winding head 10 in the opposite circumferential direction.

[0034] As a final step, the method according to the invention comprises a step d) of joining, in particular welding, of in particular stripped conductor ends 6e to form the stator winding 7.

[0035] According to the invention, the forming of the conductor ends according to step c) comprises two steps c) i.) and c) ii.).

[0036] According to the first step c) i.) according to the invention, the conductor ends 6e of the winding head layers 11 are pre-bent with at least one bending tool 13 of a first forming device 12.1.

[0037] The pre-bending of the conductor ends 6e according to the first step c) i.) is shown schematically in figures 4A-4F for a first winding head layer 11.1 and in figures 5A-5F for a second winding head layer 11.2 to be pre-bent in the opposite direction in several partial steps.

[0038] The bending tool 13 for pre-bending the conductor ends 6e of a single winding head layer 11 is immersed to a penetration depth T into a free space 14 of the respective winding head layer 11 and moved along a tool circular path 15 corresponding to the respective winding head layer 11. During movement along the tool circular path 15, the immersed section of the bending tool 13 bends the conductor ends 6e of the winding head layer 11 individually and successively in the circumferential direction. The pre-bending of the conductor ends 6e can also include an elastic component, which leads to a partial springback of the conductor ends 6e.

[0039] The penetration depth T of the bending tool 13 into the free space 14 of the respective winding head layer 11 is chosen such that the conductor ends 6e are pre-bent in the circumferential direction by one to two stator slots 4 in step c) i.)

[0040] The bending tool 13 of the first forming device 12.1 can, for example, be provided as a projection, in particular as a tooth, point, or bending finger, especially in a triangular shape, on a rotary device rotatable about a stator axis 5, for example a rotary shaft, a rotary table, or a robot arm. The rotary device can be moved continuously or in steps. The bending tool 13 has, for example, a chamfer 13s on both circumferential sides, since it is moved in both circumferential directions for the pre-bending of the different winding head layers 11.

[0041] At least one bending tool 13 of the rotary device can be designed to be adjustable in the radial direction in order to adapt the tool circular path 15 to the winding head layer 11 to be pre-bent.

[0042] The movement of the bending tool 13 along the tool circular path 15 is also shown in Fig. 2.

[0043] During pre-bending in the first step c) i.) along the tool's circular path 15, the bending tool 13 encounters the individual conductor ends 6e of the respective winding head layer 11, whereby the respective conductor end 6e is pushed away by the bending tool 13 in the direction of the movement of the bending tool 13 and circumferentially towards the stator body 3, forming a pre-bending, until the bending tool 13 can pass the respective conductor end 6e. Figures 4A to 4D show the pre-bending of the first winding head layer 11.1 during a first revolution of the bending tool 13. Figures 4E and 4F show the pre-bending of the first winding head layer 11.1 during the second revolution of the bending tool 13. Figures 5A to 5D show the pre-bending of the second winding head layer 11.2 during a first revolution of the bending tool 13. Figures 5E and 5F show the pre-bending of the second winding head layer 11.2 during the second revolution of the bending tool 13.

[0044] In the first step c) i.) the bending tool 13 makes at least one revolution, in particular several revolutions, on the respective circular path 15 for each winding head layer 11. In the first step c) i.) the penetration depth T of the bending tool 13 can be increased after at least one revolution (as shown in Fig. 5E) in order to achieve a progressively stronger pre-bending of the conductor ends 6e of the respective winding head layer 11 with each revolution.

[0045] After an initial forming of the stator winding 7, in steps c) i.) and / or c) ii.), the winding head layers 11 in the unconnected winding head 10 can be supported individually or in pairs in a radial direction with respect to a stator axis 5, in particular on both sides. This can be done, for example, with ring-shaped support tools 21 that are applied to the circumference of the respective winding head layers 11. When winding head layers 11 are supported in pairs, two adjacent winding head layers 11 are supported. The adjacent winding head layers 11 thus form layer pairs. In the unconnected winding head 10, radial gaps are formed between the layer pairs before pre-bending, so that sufficient clearance is provided in the winding head 10 for a means of radial support, for example, a support wall on the respective forming device 12.1, 12.2.

[0046] After a second execution of the stator winding 7, in step c) i.) and / or c) ii.), the radially outermost and / or radially innermost winding head layer 11 in the unconnected winding head 10 can be supported in the radial direction with respect to the stator axis 5. This can be done, for example, with ring-shaped support tools 21 that are applied to the circumference of the respective winding head layers 11. In this way, the conductor ends 6e of the respective winding head layer 11 cannot deflect in the radial direction during pre-bending and / or final bending, so that the desired deformation of the conductor ends can be achieved.

[0047] In step c) i.), the winding head layers 11 are pre-bent individually one after the other using the bending tool 13. Alternatively, several winding head layers 11 can be pre-bent simultaneously using several bending tools 13.

[0048] Fig. 6 shows the unconnected winding head 10 after the pre-bending of the conductor ends 6e of all winding head layers 11 according to the invention.

[0049] After pre-bending all winding head layers 11 according to step c) i.) the conductor ends 6e of the respective joining pair 16 cross each other.

[0050] According to the second step c) ii.) of the invention, the pre-bent conductor ends 6e of the unconnected winding head 11 are fully bent by axially pressing a forming punch 20 of a second forming device 12.2 onto the unconnected winding head 10. The intersection of the conductor ends 6e of the joining pairs 16 is retained.

[0051] Fig. 6 also shows the forming die 20 of the second forming device 12.2, which is placed on the unconnected winding head 10 for the final forming of the unconnected winding head 10 and applies a pressing force to the winding head 10 for the final bending of the pre-bent conductor ends 6e. During the final bending of the pre-bent conductor ends 6e, the winding head height 10h of the unconnected winding head 10 is reduced.

[0052] The forming die 20, which is for example ring- or disc-shaped, acts, for example, with a ring- or disc-shaped die side on a ring-shaped top side of the unconnected winding head 10.

[0053] Fig. 7 shows the finished winding head after application of the forming die according to Fig. 6.

[0054] After final bending in step c) ii.), the conductor ends 6e of the winding head 10 each have a bending radius R at the exit from the stator body 3, which is generated by the bending process and is particularly in the range of 20-30 mm. According to the invention, the ratio of the stator outer diameter D to the bending radius R can be in the range between 5 and 10.

Claims

Claims 1. Method for manufacturing a stator (1) of an electrical machine (2), the method comprising the steps: a. providing a stator body (3), in particular a stator lamination stack, with stator slots (4), b. inserting conductor elements (6), in particular hairpins or I-pins, of a stator winding (7) to be manufactured into the stator slots (4) forming at least one unconnected winding head (10), the unconnected conductor ends (6e) of which are arranged in annular winding head layers (11), c. forming the conductor ends (6e) of the unconnected winding head (10) circumferentially with a forming device (12) such that joining pairs (16) of opposing conductor ends (6e) to be joined are formed, d. Joining, in particular welding, of in particular stripped conductor ends (6e) to form the stator winding (7), characterized in that the forming of the conductor ends (6e) according to step c) comprises the steps: i.ii. Pre-bending the conductor ends (6e) of the winding head layers (11) with at least one bending tool (13) of a first forming device (12.1), wherein the bending tool (13) is immersed with a penetration depth (T) into a free space (14) of the respective winding head layer (11) for pre-bending the conductor ends (6e) of a single winding head layer (11) and is moved on a tool circular path (15) corresponding to the respective winding head layer (11) and thereby bends the conductor ends (6e) of the winding head layer (11) individually and successively in the circumferential direction with the immersed tool section, ii. Finish bending of the pre-bent conductor ends (6e) of the unconnected winding head (10) by axially pressing a forming punch (20) of a second forming device (12.2) onto the unconnected winding head (10) while reducing a winding head height (10h) of the unconnected winding head (10).

2. Method according to claim 1, characterized in that the bending tool (13) in step c) i.) along the movement on the tool circular path (15) encounters the individual conductor ends (6e) of the respective winding head layer (11), wherein the respective conductor end (6e) is pre-bent by the bending tool (13) in the direction of the Movement of the bending tool (13) and is pushed away towards the stator body (3) until the bending tool (13) can pass the respective conductor end (6e).

3. Method according to one of the preceding claims, characterized in that the winding head layers (11) are pre-bent individually one after the other by means of the bending tool (13) in step c) i.) per layer (11).

4. Method according to one of the preceding claims, characterized in that the penetration depth (T) of the bending tool (13) is selected such that the conductor ends (6e) are pre-bent by one to two stator slots (4) in step c) i.).

5. Method according to one of the preceding claims, characterized in that the bending tool (13) in step c) i.) makes at least one revolution, in particular several revolutions, on the respective tool circular path (15) per winding head layer (11).

6. Method according to claim 5, characterized in that the penetration depth (T) of the bending tool (13) is increased in step c) i.) after at least one revolution for further pre-bending of the conductor ends (6e).

7. Method according to one of the preceding claims, characterized in that in step c) i.) and / or c) ii.) a. the winding head layers (11) in the unconnected winding head (10) are supported individually or in pairs in a radial direction with respect to a stator axis (5), in particular on both sides, or b. the outermost and / or innermost winding head layer (11) in the unconnected winding head (10) is supported in a radial direction with respect to a stator axis (5).

8. Method according to one of the preceding claims, characterized in that the conductor ends (6e) of a joining pair (16) cross after step c) i.) and after step c) ii.).

9. Method according to one of the preceding claims, characterized in that the conductor ends (6e) of the winding head (10) after step c) ii.) each have a bending radius (R) generated by bending at the exit from the stator body (3), which is particularly in the area of 20-30mm, with the ratio of stator outer diameter (D) to bending radius (R) being particularly in the range between 5 and 10.

10. Method according to one of the preceding claims, characterized in that the bending tool (13) of the first forming device (12.1) is provided as a projection, in particular as a tooth, point or bending finger, especially in a triangular shape, on a rotary device rotatable about a stator axis (5), in particular a rotary shaft, a rotary table or a robot arm.

11. Method according to claim 10, characterized in that the at least one bending tool (13) of the rotary device is adjustable in the radial direction to adapt the tool circular path (15) to the winding head layer (11) to be pre-bent.

12. Stator (1) of an electrical machine (2) manufactured according to a method according to one of the preceding claims.

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