Method for producing a stator for an axial flux machine by means of a manufacturing device, stator, axial flux machine, and manufacturing device

Abstract

Method for producing a stator (12) for an axial flow machine (14) by means of a production device (10), comprising the steps: - Providing at least three first coil units (26), wherein one coil unit (26) is substantially circular segment-shaped; - welding the three first coil units (26) to form at least one first circular segment (20) by means of a welding device (28) of the manufacturing device (10), wherein the welding is carried out on a radially viewed inner side (32) of the first circular segment (20); - Providing at least three second coil units (26), wherein one coil unit (26) is substantially circular segment-shaped; - welding the three second coil units (26) to form at least one second circular segment (22) by means of the welding device (28), wherein the welding is carried out on a radially viewed inner side (32) of the second circular segment (22); and - Arranging the first circle segment (20) and the second circle segment (22) in a holding device of the manufacturing device (10) for the stator (12).

Description

[0001] The invention relates to a method for producing a stator for an axial flux machine by means of a production device according to the applicable patent claim 1. Furthermore, the invention relates to a stator, an axial flux machine and a production device.

[0002] Challenges in automating the joining process for laser bonding coil units to the inner and outer switching rings of a stator of an axial flux machine are already known in the state of the art. In particular, complex clamping devices and limited accessibility hamper a reliable, automated process for the bonding / welding process, as well as accessibility for extraction systems or pre-, in-, and post-process quality assurance measures, such as lighting for the Vision Line camera system or optical sensors. The arrangement of the stator's joining partners in a complete circle with inward-facing joints prevents the laser beam from irradiating perpendicularly to the joints of the inner switching ring and the coils.

[0003] GB 25 34 195 A describes a method of assembling an axial-flux stator housing chamber comprising radial walls and inner and outer side walls containing a set of coils wound on respective stator bars arranged circumferentially at intervals around an axis of the machine, with collapsible elements on the radial walls opposing the side walls. The attachment of the side and radial walls comprises controlling one or both of the spacing and a degree of parallelism of the first and second radial walls by controlled collapsing of the collapsible elements and pressure, with laser welding beams directed around the peripheral edge of the end walls. The collapsible elements may be provided at only one end of the radial walls or on the side walls. In alternative embodiments, the stator housing chamber comprises two clamshells with collapsible elements formed on the shells.The radial walls can be made of a high-temperature thermoplastic polymer, such as PPA, and the collapsible elements can be made of a polymer. Alternatively, the collapsible element can be an adhesive, for example, if the walls are made of metal.

[0004] EP 3 745 559 B1 discloses a stator of an axial flux machine, comprising an inner structure, an intermediate structure, and an outer structure, all arranged coaxially around a central axis. The inner structure comprises a plurality of rotationally symmetrically arranged stator elements made of a ferromagnetic core and a coil wound therearound, all of which are of identical design. The intermediate structure comprises a plurality of compression elements, which are pressed radially inward against the stator elements by the outer structure, thereby compressing the coils and mechanically securing the stator elements.

[0005] US 2013 / 0 140 920 A1 discloses a stator assembly structure for an axial-flux electric machine, which, however, has a return iron as a yoke. The special structure of the stator with tooth-like projections enables a connection thereto with a disc-shaped stator seat, wherein the stator seat is made of a material suitable for casting or molding. Using a winding as a coil, the stator is assembled onto the stator seat as a stator assembly. Here, both elements mesh tightly at the contact surfaces of the stator and the stator seat, enabling good transmission and stability.

[0006] In addition, DE 10 2020 113 179 A1 describes a method for monitoring a connection surface during laser welding of copper-containing, bent bar conductors in the form of hairpins for an electric motor, wherein two bar conductors are arranged partially overlapping and are welded together by means of a processing laser beam, wherein a welding bead is formed by which the bar conductors are connected to each other, wherein after the end of the action of the processing laser beam during the cooling of the welding bead at least one measurement variable which changes with the temperature of the welding bead is measured at least a part of the welding bead as a function of time, that from the at least one measured measurement variable a dependent on the heat capacity of the welding bead

[0007] parameter is determined, and that the connection area is determined qualitatively or quantitatively from the parameter.

[0008] The object of the present invention is to provide a method for producing a stator, a stator, an axial flux machine and a manufacturing device by means of which a stator can be produced in an improved manner or by means of which an improved stator can be provided.

[0009] This object is achieved by a method, a stator, an axial flux machine, and a manufacturing device according to the independent patent claims. Advantageous embodiments are specified in the subclaims.

[0010] One aspect of the invention relates to a method for producing a stator for an axial flux machine using a manufacturing device. At least three first coil units are provided, one coil unit being substantially circular segment-shaped. The three first coil units are welded together to form at least one first circular segment using a welding device of the manufacturing device, the welding being performed on a radially viewed inner side of the first circular segment. At least three second coil units are provided, one coil unit being substantially circular segment-shaped. The three second coil units are welded together to form at least one second circular segment using the welding device, the welding being performed on a radially viewed inner side of the second circular segment.The first circle segment and the second circle segment are then arranged in a holding device of the stator manufacturing device.

[0011] In particular, the stator is then manufactured by arranging and, for example, further welding.

[0012] In particular, the invention describes a special connection of the stator to the inner switching ring, which enables a division of the joining process for the stator. In this case, the stator is divided into at least two, preferably three or more circular segments for welding the coils to the inner switching ring. The welded segments are then joined together to form the entire stator. Welding of an outer switching ring can then be carried out.

[0013] In particular, the invention has the advantage that vertical irradiation, for example of a laser, is possible as a welding process onto the joining partners, in particular the inner switching ring and the corresponding coil units. This enables process stabilization and the transfer of the hairpin joining process. Furthermore, simple handling and automation of joining steps are provided. Furthermore, improved accessibility to the joining points can be created, in particular for the clamping and extraction device, so that pre-, in-, and post-process quality assurance can also be provided. This can be provided, for example, in the form of lighting, a vision line, or optical sensors. Furthermore, the division into subgroups reduces rejects in the case of unsatisfactory welds, thus enabling simple rework.In particular, this can reduce the complexity within the clamping device and provide a reduction in risk when implementing a fully automated joining station.

[0014] According to an advantageous embodiment, after the arrangement, a radially outer contact is created between the at least two circular segments. The outer contact is, in particular, an outer contact ring. The outer contact ring is essentially incomplete. Thus, reliable production of the stator can be achieved based on the contact ring.

[0015] It is also advantageous if the radially outer contact of the respective coil units is already created when the respective circular segments are provided. For example, it can be provided that the outer contact of the circular segments is made after the inner contact of the circular segments has been created. The already pre-contacted circular segments are then arranged together to form the stator. This allows the stator to be manufactured in a simple manner.

[0016] It has also proven advantageous to use a laser welding device for welding. The laser welding process, in particular, has the advantage of allowing the contacts to be welded simply, quickly, and reliably.

[0017] Furthermore, it has proven advantageous if the circular segments are moved relative to the welding device for welding. In particular, the welding device, for example a laser device, is thus arranged in a fixed position on the production device. The circular segments can then be reliably moved relative to the welding device, particularly with the holding device. This allows for a simple process for producing the internal contacts.

[0018] Furthermore, it has proven advantageous if at least a third circular segment is created and the stator is manufactured from the at least three circular segments. In particular, the circular segments thus essentially have a 120-degree circular segment surface. These can then be reliably joined together. Particularly with the at least three circular segments, it is particularly advantageous that the inner surface, or the inside, can be reliably reached by the welding device. This allows the stator to be manufactured reliably.

[0019] A further advantageous embodiment provides that at least six coil units are provided for each circular segment and welded from the inside. In particular, the six coil units per circular segment make it possible to create a stator capable of generating high power. Thus, for example, the axial flux machine can be designed as a traction unit within an at least partially electrically powered motor vehicle. It is obvious to those skilled in the art that more than six coil units, in particular a multiple of three coil units, can be provided within the circular segments and welded accordingly.

[0020] A further aspect of the invention relates to a stator which is manufactured according to a manufacturing method according to the preceding aspect.

[0021] Furthermore, the invention also relates to an axial flux machine with at least two rotors and a stator according to the preceding aspect. In particular, the axial flux machine comprises a first rotor, the stator, and then a second rotor. Thus, the axial flux machine can be reliably implemented, for example, in a motor vehicle.

[0022] Furthermore, the invention also relates to a manufacturing device for producing a stator for an axial flux machine, comprising at least one welding device and a holding device, wherein the manufacturing device is designed to carry out a method according to the preceding aspect. In particular, the stator is manufactured using the manufacturing device.

[0023] Advantageous embodiments of the method are considered to be advantageous embodiments of the stator, the axial flux machine, and the manufacturing device. In particular, the manufacturing device has specific features enabling the stator to be manufactured accordingly.

[0024] Further advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and from the drawings. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures, can be used not only in the respective specified combinations, but also in other combinations or on their own, without departing from the scope of the invention.

[0025] Showing: Fig. 1 is a schematic perspective view of an embodiment of an axial flow machine; Fig. 2 a schematic plan view of an embodiment of a stator; Fig. 3 is a further schematic plan view of an embodiment of a manufacturing device with a stator; and Fig. 4 a further schematic view of an embodiment of a stator.

[0026] In the figures, identical or functionally identical elements are provided with the same reference symbols.

[0027] Fig. 1 shows a schematic view of an embodiment of a manufacturing device 10 for a stator 12 or for an axial flux machine 14. The axial flux machine 14 comprises, in particular, the stator 12, a first rotor 16, and a second rotor 18. In the present embodiment, the axial flux machine 14 is shown purely as an example.

[0028] Fig. 2 shows a schematic plan view of one embodiment of a stator 12. In the present embodiment, the stator 12 has three circular segments 20, 22, and 24. Each circular segment 20, 22, and 24 in turn has at least three coil units 26. In particular, in the present embodiment, each circular segment 20, 22, and 24 has six coil units 26. In the present embodiment, the coil units 26 are welded to one another, in particular, at an inner circular ring 28.

[0029] Fig. 3 shows a further schematic plan view of an embodiment of a manufacturing device 10. In the present exemplary embodiment, the manufacturing device 10 has, in particular, a welding device 28, in this case in particular in the form of a laser welding device 28. The laser welding device 28 can generate a laser beam 30, which in turn welds the coil units 26 on a radially viewed inner side 32.

[0030] In particular, the Fig. 3 shows a method for producing the stator 12 for the axial flux machine 14. At least three first coil units 26 are provided, one coil unit 26 being substantially circular segment-shaped. The three first coil units 26 are then welded together to form at least one circular segment 20, 22, 24, the welding being performed on the radially viewed inner side 32 of the circular segment 20, 22, 24. The further coil units 26 are then provided, in particular from a further circular segment 20, 22, 24, the coil units 26 then being welded together from the radially viewed inner side 32.

[0031] For this purpose, it can be provided, for example, that after the arrangement a radially viewed outer contact 34 ( Fig. 4) is generated between the at least two circular segments 20, 22, 24. Furthermore, a radially viewed external contact 34 of the respective coil units 26 can already be generated by providing the respective circular segments 20, 22, 24.

[0032] As in the Fig. 3, the circle segments 20, 22, 24 can be moved relative to the welding device 28, in particular for welding, which is represented here by an arrow 36.

[0033] As in the Fig. 2 and the Fig. 3, in particular three circle segments 20, 22, 24 can be provided.

[0034] In particular, the invention proposes grouping the single-pole windings, which in this case correspond in particular to the coil units 26, in the axial flux machine 14 into segments / modules for welding, which can each be easily welded from the inside in the segment arrangement and contacting of the windings radially inward between the circular segments 20, 22, 26 is no longer necessary. This means that the welding process, in particular laser welding, can also be carried out in the radial inner region using conventional devices and essentially has no spatial restriction in the beam path. The circular segments 20, 22, 24 are designed in such a way that the windings only need to be contacted in the radial outer region and thus when connecting the circular segments 20, 22, 24 to the stator 12, welding is no longer necessary on the inside, but only from the outside.

[0035] The welding points on the outside of the circular segments 20, 22, 24, in particular within the circular segments 20, 22, 24, can be welded directly during the production / connection of the circular segments 20, 22, 24, so that the circular segments 20, 22, 24 are plated through and only need to be connected, or the individual pole windings, i.e. the coil units 26, can also all be welded together on the outside only after the circular segments 20, 22, 24 have been joined together to form the stator 12 and together with the welding of the segments 20, 22, 24.

[0036] To make this possible, the individual pole windings must have different contact points in order to be contacted from the inside and the outside. Fig. 4, in particular, four different coil units 26, in particular designated 26a to 26d here. As already mentioned, the coil units 26a to 26d can be represented differently, which are then arranged in particular in the at least two circular segments 20, 22, 24, whereby there is no longer any internal contact between the two circular segments 20, 22, 24 and therefore no contacting / welding is required here. Depending on the winding design, the type / number / differences between the designs of the individual pole windings can also vary, so this is only one exemplary embodiment.

[0037] Depending on the design, the connections of the individual pole windings can also be made directly, for example with a long overhang of the winding wires and thus particularly with a single welding process, or via interconnection components, such as additional conductors, which enable spatial bridging and therefore arrangement and handling, but must be connected at both ends and thus require two welding processes. The key advantage here is the free beam paths for the internal welding when the individual stator windings are designed as at least two circular segments 20, 22, 24, which are contacted radially to one another within the circular segments 20, 22, 24, but across the circular segments 20, 22, 24, contact only takes place externally.

[0038] The Fig.4 shows, particularly on the right-hand side, the windings, which are also more or less provided with long projections 38, but these are intended for contacting the switching ring, which distributes the three phases over the inner and outer circumference.

[0039] This switching ring does not have to have a circumferential busbar, but serves to facilitate spatial contact between the windings and is designed according to the connection points.

[0040] In particular, since in axial flux machines 14 the windings do not have to be welded axially but radially next to them, which makes the beam path very difficult, especially radially inward, this invention solves the problem by dividing the winding into the circular segments 20, 22, 24, in that the circular segments 20, 22, 24 are pre-contacted by carrying out the welding at the contact points that will later be located radially inward before joining them in a ring shape, and therefore the access is not yet restricted. List of reference symbols 10 Manufacturing device 12 Stator 14 axial flux machine 16 first rotor 18 second rotor 20 first circle segment 22 second circle segment 24 third circle segment 26 Coil unit 28 Welding device 30 laser beam 32 Inside 34 Contact ring 36 Arrow 38 overhang

Claims

[1] Method for producing a stator (12) for an axial flow machine (14) by means of a manufacturing device (10), comprising the steps: - Providing at least three first coil units (26), wherein one coil unit (26) is substantially circular segment-shaped; - welding the three first coil units (26) to form at least one first circular segment (20) by means of a welding device (28) of the manufacturing device (10), wherein the welding is carried out on a radially viewed inner side (32) of the first circular segment (20); - Providing at least three second coil units (26), wherein one coil unit (26) is substantially circular segment-shaped; - welding the three second coil units (26) to form at least one second circular segment (22) by means of the welding device (28), wherein the welding is carried out on a radially viewed inner side (32) of the second circular segment (22); and - Arranging the first circle segment (20) and the second circle segment (22) in a holding device of the manufacturing device (10) for the stator (12). [2] Method according to claim 1 characterized by that after the arrangement, a radially external contact is created between the at least two circular segments (20, 22, 24). [3] Method according to claim 1 characterized by that a radially viewed outer contact of the respective coil units (26) is already generated when the respective circular segments (20, 22, 24) are provided. [4] Method according to one of the preceding claims, characterized bythat the welding is carried out using a laser welding device. [5] Method according to one of the preceding claims, characterized by that the circular segments (20, 22, 24) are moved relative to the welding device (28) for welding. [6] Method according to one of the preceding claims, characterized by that at least a third circular segment (24) is produced and the stator (12) is manufactured from the at least three circular segments (20, 22, 24). [7] Method according to one of the preceding claims, characterized by that for each circular segment (20, 22, 26) at least six coil units (26) are provided and welded from the inside. [8] Stator (12) manufactured by a manufacturing method according to one of claims 1 to 7. [9] Axial flux machine (14) with at least two rotors (16, 18) and a stator (12) according to claim 8. [10] Manufacturing device (10) for producing a stator (12) for an axial flux machine (14), with at least one welding device (28) and a holding device, wherein the manufacturing device (10) is designed to carry out a method according to one of claims 1 to 7.

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