Method for producing a coil for an axial flux machine of an electric drive machine and winding device

Abstract

The invention relates to a method for producing a coil (14) for an axial flux machine of an electric drive motor of an at least partially electrically operated motor vehicle by means of a winding device (12), comprising the steps of: winding a stranded wire (16) around a punch (10) of the winding device (12), wherein the punch (10) has an inner contour of the coil (14); lowering a die (20) onto the punch (10) and thereby applying a compressive force to the wound stranded wire (16) by means of the die (20), wherein the die (20) has an outer contour of the coil (14); raising the die (20); and repeating steps a) to c) until a predetermined number of windings is reached. The invention further relates to a winding device (12).

Description

[0001] The following invention relates to a method for producing a coil for an axial flux machine of an electric drive motor of an at least partially electrically operated motor vehicle by means of a winding device according to the applicable patent claim 1. Furthermore, the invention relates to a corresponding winding device.

[0002] The disc-shaped design of axial flux machines or axial flux motors (AFMs) enables innovative axle drive concepts for motor vehicles. Due to space constraints, the outer diameter of the axial flux machine is relatively limited, especially for coaxial applications in motor vehicles. Therefore, and also for efficiency reasons, an increase in the winding ratio is being sought for future large-scale production. Accordingly, stranded wire is used, particularly for efficiency benefits at high frequencies, to reduce copper losses, such as skin effects and proximity effects.

[0003] However, no stable production process is known for manufacturing coils for axial flux machines from stranded wire. Due to the very low dimensional rigidity of stranded wire, which also depends heavily on the diameter and number of individual wires, winding processes known from flat wire winding are unsuitable for this application. On the other hand, the flexibility of stranded wires can also be specifically utilized in the winding process.

[0004] DE 10 2022 134 667 A1 relates to an electrical coil comprising a winding wire wound into a plurality of coil turns. The winding wire comprises a stranded wire comprising a plurality of thin, twisted individual wires, and the stranded wire is covered with winding insulation. It is provided that the coil turns are wrapped with a fixing band at least at a distance apart, which locally encloses and geometrically fixes the coil turns in a compressed state of the coil.

[0005] The object of the present invention is to provide a method and a winding device by means of which a coil for an axial flux machine can be produced in a simple manner.

[0006] This object is achieved by a method and a winding device according to the independent patent claims. Advantageous embodiments are specified in the subclaims.

[0007] One aspect of the invention relates to a method for producing a coil for an axial flux machine of an electric drive motor of an at least partially electrically powered motor vehicle using a winding device. A stranded wire is wound around a punch of the winding device, wherein the punch has an inner contour of the coil. A die is lowered onto the punch, thereby subjecting the stranded wire to a compressive force by means of the die, wherein the die has an outer contour of the coil. The die is raised, and the steps are repeated until a predetermined number of windings is reached.

[0008] This allows a coil to be manufactured in a simple manner, particularly based on stranded wires. In particular, a triangular or trapezoidal coil shape can be created.

[0009] In particular, an implementation is proposed in which a stranded wire process can be wound safely and optimised even for coils of an axial flux machine and thus in particular in triangular or trapezoidal form, by compressing the stranded wire again after winding in the final form, for example by means of a press matrix.

[0010] The invention relates in particular to the coils of axial flux machines. Here, a stranded wire is wound, the individual wires of which are made, for example, of copper or aluminum or an alloy of these elements. This wire can optionally already be profiled in a rectangular shape. The stranded wires are coated with a layer that has an electrically insulating effect. This layer must also be mechanically robust in order to withstand the forces during forming. If necessary, baking varnish is used as a coating so that the stranded wires can then be baked to create dimensional stability. The contour of the coil to be produced can be triangular or trapezoidal and can optionally have rounded edges. The cross-section of the stranded wires can be circular, but can also have other geometries.

[0011] The winding device, or rather the tool for creating the winding, consists primarily of the punch and the die. These, in turn, are made of a thermally and mechanically robust material. The punch has the inner contour of the coil and a support surface for the wire. Additional features include, for example, a wire guide and fixation. The die, in turn, has the outer contour of the coil and also a support surface for pressing the wire. If necessary, the tool can also be coated with a low-friction coating or other separating layer.

[0012] The invention compensates for the thickening and de-creasing of stranded wire in bends, as well as for bulging of the flanks. The pressing process compresses the layers of stranded wire within the coil. This allows for a better geometric shape of the coil and a corresponding increase in the fill factor. After the pressing process, the individual conductors are not only preferably circular, but can also have any other shape due to the pressing process.

[0013] In particular, the invention enables the production of stranded wire windings for axial flux machine applications. Efficiency advantages in the operation of the axial flux machine are achieved through the use of stranded wire. Furthermore, thermal advantages are realized as a result of increased efficiency, allowing for lower cooling requirements. Furthermore, lower heat radiation within the rotor, and thus greater counter-field stability, is achieved.

[0014] According to an advantageous embodiment, during a first winding of the stranded wire around the punch, the stranded wire is held on the punch by a wire guide.

[0015] It is also advantageous if the punch is fixed in place to wrap the strand around the punch and the strand is guided around the punch.

[0016] Furthermore, it can be provided that in order to wrap the strand around the punch, the strand is fixed and the punch is rotated.

[0017] A further aspect of the invention relates to a winding device for producing a coil for an axial flux machine of an electric drive motor of an at least partially electrically powered motor vehicle, comprising at least one punch and a die, wherein the winding device is configured to produce the coil using the preceding method. In particular, the method is also carried out using the winding device.

[0018] Advantageous embodiments of the method are to be regarded as advantageous embodiments of the winding device. The winding device has specific features for this purpose in order to be able to carry out corresponding method steps.

[0019] Further advantages, features, and details of the invention will become apparent from the following description of a preferred embodiment 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 combinations specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0020] Showing: Fig. 1 is a schematic perspective view of an embodiment of a punch of an embodiment of a winding device; Fig. 2 a schematic plan view of the stamp from Fig. 1; Fig. 3 a schematic perspective view of an embodiment of the stamp from the Fig. 1 and Fig. 2 and an embodiment of a die of the winding device; Fig. 4 a schematic flow diagram according to an embodiment of the manufacturing method.

[0021] In the figures, identical or functionally identical elements are provided with the same reference symbols.

[0022] Fig. 1 shows a schematic perspective view of an embodiment of a punch 10 of a winding device 12 ( Fig. 3) for producing a coil 14 for a non-illustrated axial flux machine of a non-illustrated motor vehicle, wherein the motor vehicle is designed in particular as an at least partially electrically operated motor vehicle.

[0023] In the present exemplary embodiment, a stranded wire 16 is already wound in several layers around the punch 10. In the present exemplary embodiment, the punch 10 has a wire guide 18. Furthermore, it is shown that the punch 10 has a triangular contour with rounded corners. In particular, the triangular contour corresponds to the inner geometry / inner contour of the coil 14.

[0024] Fig. 2 shows the coil 14 with the punch 10 again from a top view.

[0025] Fig. 3 shows a schematic perspective view of the winding device 12. In particular, the punch 10 and a die 20 are shown. In particular, it is provided that the punch 10 of the winding device 12 is wound with the stranded wire 16, wherein the punch 10 has an inner contour of the coil 14. The die 20 is then lowered onto the punch 10, thereby applying a compressive force to the stranded wire 16 by means of the die 20, wherein the die 20 has an outer contour of the coil 14. The die 20 is then raised again. The aforementioned steps are repeated until a predetermined number of windings is reached.

[0026] In particular, it is provided that when the stranded wire 16 is wound around the punch 10, the punch 10 is fixed and the stranded wire 16 is guided around the punch 10. Alternatively, it can be provided that for winding the stranded wire 16 around the punch 10, the stranded wire 16 is fixed and the punch 10 is rotated.

[0027] Fig.4 again shows a schematic flow diagram according to an embodiment of the manufacturing method for producing the coil 14. In particular, in a first step S1, it can be provided that the stranded wire 16 is inserted into the wire guide 18. This can then be fixed so that it can no longer move relative to the tool itself, in particular formed from the punch 10 and the die 20. In a second step S2, the stranded wire 16 is bent around the punch 10 in the xy plane. For this purpose, the punch 10 can rotate and the stranded wire 16 can be firmly guided, or the stranded wire 16 can be guided around the spatially fixed punch 10. In a third step S3, the die 20 is placed on the punch 10 and pressed in the z-direction. This compresses the stranded wire 16 in the z-direction. The walls of the die prevent expansion in the x- or y-direction.This step can be performed after performing a bend, bending a layer, or bending the entire coil 14 with the desired number of layers or windings. In a fourth step S4, the dimensional stability of the wound coil 14 is achieved. Various options exist for this: Stranded wires 16 coated with baking varnish can be baked. With other coatings, the coil 14 can be potted or glued. This process step is carried out in the die and under the action of force in the z-direction in order to achieve the desired geometry. The elastic deformation that causes the springback must be taken into account. In a fifth step S5, as soon as the coil 14 is dimensionally stable, the die 20 can be removed in order to release the coil 14 from the punch 10. List of reference symbols 10 stamps 12 Winding device 14 coil 16 stranded wire 18 Wire guide 20 die S1 - S5 steps of the procedure QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2022 134 667 A1

[0004]

Claims

[1] Method for producing a coil (14) for an axial flux machine of an electric drive machine of an at least partially electrically operated motor vehicle by means of a winding device (12), comprising the steps: a) winding a stranded wire (16) around a stamp (10) of the winding device (12), the stamp (10) having an inner contour of the coil (14); b) lowering a die (20) onto the punch (10) and thereby applying a compressive force to the wound stranded wire (16) by means of the die (20), wherein the die (20) has an outer contour of the coil (14); c) lifting the die (20); and d) Repeat steps a) to c) until a specified number of windings is reached. [2] Method according to claim 1, characterized by that during a first winding of the stranded wire (16) around the punch (10), the stranded wire (16) is held on the punch (10) by a wire guide (18). [3] Method according to claim 1 or 2, characterized by that in order to wrap the stranded wire (16) around the punch (10), the punch (10) is fixed and the stranded wire (16) is guided around the punch (10). [4] Method according to claim 1 or 2, characterized by that in order to wrap the stranded wire (16) around the punch (10), the stranded wire (16) is fixed and the punch (10) is rotated. [5] Winding device (12) for producing a coil (14) for an axial flux machine of an electric drive machine of an at least partially electrically operated motor vehicle, with at least one punch (10) and a die (20), wherein the winding device (12) is designed to produce the coil according to a method according to one of claims 1 to 4.

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