Method for manufacturing a stator for an electric machine and electric motor

Abstract

The present invention relates to a method for manufacturing a stator (1) for an electric machine (2), comprising: - Providing a stator body (3) with stator slots (4), wherein hairpins (5) are arranged in the stator slots (4), wherein the hairpins (5) are arranged in a first slot layer (6), several inner slot layers (7) and a final slot layer (8) in the stator slots (4), wherein free first hairpin ends (9) of the hairpins (5) are separated from each other, - Gripping two directly adjacent first hairpin ends (9) with a common setting tool (10), - Jointly setting the first hairpin ends (9) with the common setting tool (10), and - Welding the first hairpin ends (9) of different stator slots (4) together in pairs using a welding device. Furthermore, the invention relates to an electric machine (2), in particular for a motor vehicle.

Description

[0001] The present invention relates to a method for producing a stator for an electric machine, in particular for a motor vehicle, according to the preamble of independent claim 1. Furthermore, the invention relates to an electric machine, in particular for a motor vehicle, according to the preamble of independent claim 10.

[0002] Methods for producing stators for electrical machines are known in which a stator base body of the stator is equipped with a plurality of hairpins. For this purpose, the stator base body has a plurality of stator slots in which the hairpins are stacked one above the other in the radial direction such that free first hairpin ends of the hairpins protrude in the axial direction on a first stator end face of the stator and free second hairpin ends of the hairpins protrude in the axial direction on a second stator end face of the stator opposite the first stator end face. Alternatively, the hairpins can also be provided as U-pins, so that only hairpin bends of the hairpins are arranged on the second stator end face.

[0003] The free hairpin ends are then distributed radially. This process is also referred to as "expanding." Document DE 10 2018 206 004 A1 describes a device and method for expanding the hairpin ends.

[0004] After expanding, the free hairpin ends are set radially to align the hairpin ends to be welded together. Devices and methods for setting the hairpin ends are known from documents DE 10 2019 211 713 A1 and US 2018 / 375 409 A1. For this purpose, the free hairpin ends are each clamped in a setting tool and set in such a way that adjacent hairpin ends of a stator slot are set in different directions in the radial direction.

[0005] Known methods for manufacturing stators have the disadvantage that a separate, NC-controlled setting tool is required for setting each wire layer in the stator slot. This leads to increased manufacturing costs. Furthermore, stators with hairpin ends set alternately in different directions require more space.

[0006] Finally, the hairpin ends are often arranged very close to one another after cabinet-fitting, so that additional or particularly complex electrical insulation is required to avoid short circuits during operation of the electrical machine.

[0007] It is therefore an object of the present invention to eliminate or at least partially eliminate the disadvantages described above in a method for producing a stator for an electric machine, in particular for a motor vehicle, and in an electric machine, in particular for a motor vehicle. In particular, the object of the present invention is to provide a method and an electric machine that have an improved manufacturing process in a simple and cost-effective manner, for example by avoiding excessive tooling requirements and / or reducing installation space requirements and / or providing improved insulation.

[0008] The above object is achieved by the patent claims. Accordingly, the object is achieved by a method for producing a stator for an electric machine having the features of independent claim 1 and by an electric machine having the features of independent claim 10. Further features and details of the invention emerge from the subclaims, the description, and the drawings. Features and details described in connection with the method according to the invention naturally also apply in connection with the electric machine according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is always made to each other.

[0009] According to a first aspect of the invention, the object is achieved by a method for producing a stator for an electric machine, in particular for a motor vehicle. The method comprises: - Providing a stator base body with stator slots, wherein hairpins are arranged in the stator slots, wherein the hairpins are arranged in a first slot position, several inner slot positions and a last slot position in the stator slots, wherein free first hairpin ends of the hairpins protrude from the stator base body, - Gripping two first hairpin ends directly adjacent in the radial direction with a common setting tool, - Joint setting of the first hairpin ends with the common setting tool, and - Welding the first hairpin ends of different stator slots using a welding device.

[0010] First, the stator base body is provided with a stator longitudinal axis. The stator base body is preferably designed as a laminated core consisting of several coaxially stacked stator disks, for example, made of electrical steel. The stator disks are preferably electrically insulated from one another, for example, by baked enamel, paper, or the like. The stator disks are preferably pressed together. The stator slots are formed in the stator base body and have a slot depth in the radial direction, a slot width in the circumferential direction, and a slot length along the stator longitudinal axis.

[0011] The hairpins are arranged in the stator slots in a radial direction in several slot positions. A slot position closest to the stator longitudinal axis is referred to in the invention as the "first slot position". A slot position furthest from the stator longitudinal axis is referred to in the invention as the "last slot position". The slot positions arranged between the first slot position and the last slot positions are referred to in the invention as "inner slot positions". The hairpins are preferably arranged in the stator slots such that one hairpin is arranged in each stator slot per slot position. The hairpins preferably have a hairpin width that corresponds to the slot width or is only slightly smaller than the slot width.

[0012] Free first hairpin ends arranged on the first stator end face of the stator base body protrude from the stator base body. The first hairpin ends are preferably separated from one another. This means that the hairpins are formed in the radial direction such that the adjacent first hairpin ends of a stator slot are spaced apart from one another by a greater distance in the radial direction than within the stator slot. Within the stator slot, the hairpins are preferably arranged directly next to one another and, if necessary, spaced apart from one another by an insulator, such as paper.

[0013] A setting tool is used to grip two first hairpin ends that are directly adjacent in the radial direction, for example by sliding the setting tool on, closing the clamping jaws of the setting tool, or the like. This grips two first hairpin ends of adjacent groove layers. Preferably, the other first hairpin ends of the same two groove layers are also gripped by the same setting tool. Sliding can occur, for example, along a longitudinal extension of the first hairpin ends or transversely to the longitudinal extension. The setting tool can, for example, have a setting crown or the like. Preferably, two further first hairpin ends that are directly adjacent in the radial direction are each gripped by a different setting tool.

[0014] By moving the setting tool in the circumferential direction of the stator base body, the jointly gripped first hairpin ends are set together in one direction. Preferably, the other first hairpin ends of the same two slot positions are set in the same direction by the same setting tool. Preferably, the other paired first hairpin ends are set together in one direction by the respective corresponding setting tool. It is preferred that adjacent pairs of first hairpin ends in the stator slots be set in different circumferential directions. In this way, a particularly compact stator design can be achieved.

[0015] Finally, the first hairpin ends of different stator slots are welded in pairs using the welding device. It is preferred that a pair of radially adjacent first hairpin ends, which are set together using a setting tool, are not welded to each other, but rather preferably to each other radially adjacent first hairpin end. In this way, electrical conductors are formed that extend at least twice through the stator base body. If the hairpins are provided as U-pins, continuous electrical conductors are formed that extend through the stator base body even more often.

[0016] A method according to the invention for producing a stator for an electric machine has the advantage over conventional methods that the number of setting tools used is reduced using simple means and in a cost-effective manner by combining the first hairpin ends in pairs. Furthermore, the space required for the stator can be reduced by setting adjacent first hairpin ends together. Finally, after setting, the pairs of first hairpin ends have an increased distance from adjacent pairs of first hairpin ends, so that electrical insulation of the stator is improved and can be arranged more easily on the stator.

[0017] According to a preferred further development of the invention, a method can be provided in which the first hairpin end of the first groove layer and / or the first hairpin end of the last groove layer is / are each individually gripped and set using its own setting tool. In this case, it is preferred that the setting direction of the first hairpin end of the first groove layer and / or the first hairpin end of the last groove layer is opposite to the setting direction of the adjacent first hairpin end. Preferably, several or all of the first hairpin ends of the first groove layer are gripped and set by the own setting tool. Further preferably, several or all of the first hairpin ends of the last groove layer are gripped and set by the own setting tool.Thus, it is preferred that the first hairpin ends of the first slot position be gripped and set by a first setting tool, and the first hairpin ends of the last slot position be gripped and set by a last setting tool. This has the advantage of improving the utilization of the available installation space using simple means and in a cost-effective manner. This allows for a particularly compact stator design. Furthermore, the electrical insulation of the stator can be further improved.

[0018] According to the invention, it is preferred that the first hairpin ends of the inner slot layers are gripped and set with one another in pairs using a common setting tool. Preferably, the first hairpin ends of all inner slot layers are gripped and set with one another in pairs using a common setting tool. The setting of adjacent pairs of first hairpin ends preferably takes place in opposite directions. By setting in pairs in different directions, a particularly large distance can be achieved between adjacent first hairpin ends of different setting directions. This has the advantage that the utilization of the available installation space is improved using simple means and in a cost-effective manner. A particularly compact design of the stator can thus be achieved. Furthermore, the electrical insulation of the stator can be further improved as a result.

[0019] Further preferably, a stator base body is provided in which free second hairpin ends of the hairpins protrude from the stator base body, wherein the first hairpin ends and the second hairpin ends are formed at opposite ends of the hairpins, wherein two second hairpin ends directly adjacent in the radial direction are gripped with a common setting tool and set together, and wherein the second hairpin ends of different stator slots are welded with the welding device. In other words, hairpins are preferably used which are designed as so-called I-pins. While U-pins each have two first hairpin ends, both of which protrude from the first stator end face of the stator base body, I-pins each have a first hairpin end and a second hairpin end, wherein the first hairpin end protrudes from the first stator end face and the second hairpin end protrudes from the second stator end face.To produce the stator winding, I-pins require hairpins to be bent and welded on both stator faces. Preferably, U-pins and I-pins are used in combination, with the number of U-pins preferably being greater than the number of I-pins. Preferably, the I-pins are used to interconnect the electric machine with power electronics, preferably on one side of the stator on which the U-pins are bent by approximately 180°. This has the advantage of improving the utilization of available installation space using simple means and in a cost-effective manner. This allows for a particularly compact stator design. Furthermore, the electrical insulation of the stator can be further improved.

[0020] In a particularly preferred embodiment of the invention, a method can be provided in which the second hairpin end of the first slot position and / or the last slot position is individually gripped and set using a separate setting tool. In this case, it is preferred that the setting direction of the second hairpin end of the first slot position and / or the second hairpin end of the last slot position is opposite to the setting direction of the adjacent second hairpin end. This has the advantage that the utilization of the available installation space is improved using simple means and in a cost-effective manner. A particularly compact design of the stator can thus be achieved. Furthermore, the electrical insulation of the stator can be further improved as a result.

[0021] Preferably, the second hairpin ends of the inner slot layers are gripped and set together in pairs using a common setting tool. Preferably, the second hairpin ends of all inner slot layers are gripped and set together in pairs using a common setting tool. The setting of adjacent pairs of second hairpin ends preferably takes place in opposite directions. By setting in pairs in different directions, a particularly large distance can be achieved between adjacent second hairpin ends with different setting directions. This has the advantage that the utilization of the available installation space is improved using simple means and in a cost-effective manner. This allows a particularly compact design of the stator. Furthermore, the electrical insulation of the stator can be further improved as a result.

[0022] According to a preferred embodiment of the invention, the stator base body is provided with eight hairpins per stator slot, wherein five setting tools are used, wherein the first hairpin ends of the outer slot layers are each gripped and set with one of the setting tools and the first hairpin ends of adjacent inner slot layers are each gripped and set in pairs with one of the setting tools. Alternatively, the stator base body can be provided with four hairpins per stator slot, wherein three setting tools are used. In this case, the first hairpin ends of the outer slot layers are each gripped and set with one of the setting tools and the two first hairpin ends of the inner slot layers are each gripped and set in pairs with one of the setting tools. Alternatively, the stator base body can be provided with six hairpins per stator slot, wherein four setting tools are used.In this case, the first hairpin ends of the outer slot layers are each gripped and set with one of the setting tools, and the first hairpin ends of adjacent inner slot layers are each gripped and set in pairs with one of the setting tools. This has the advantage of allowing a stator with a particularly compact and economically viable design to be manufactured using simple means and in a cost-effective manner.

[0023] Particularly preferably, the first hairpin ends gripped in pairs by means of one of the setting tools are separated from one another in the radial direction. The separation preferably takes place in such a way that a distance in the radial direction between the respective first hairpin ends is increased. According to this preferred embodiment, the separation takes place after the joint setting. In this case, it is preferred according to the invention that the first hairpin ends of the hairpin located further outwards in the radial direction are bent radially outwards and / or the first hairpin ends of the hairpin located further inside in the radial direction are bent radially inwards. This has the advantage that the utilization of the available installation space is improved using simple means and in a cost-effective manner. A particularly compact design of the stator can thus be achieved.

[0024] It is further preferred according to the invention that the first hairpin end located further inward in the radial direction is shaped in the direction of a stator longitudinal axis of the stator base body and / or that the first hairpin end located further outward in the radial direction is shaped away from the stator longitudinal axis. Particularly preferably, the first hairpin end located further inward is shaped toward the stator longitudinal axis, and the first hairpin end located further outward in the radial direction is shaped away from the stator longitudinal axis. This has the advantage that the utilization of the available installation space is improved using simple means and in a cost-effective manner. Thus, a particularly compact design of the stator can be achieved.

[0025] According to a second aspect of the invention, this object is achieved by an electric machine, in particular for a motor vehicle. The electric machine has a stator and a rotor arranged coaxially with the stator. According to the invention, the stator is manufactured by a method according to the invention.

[0026] Accordingly, the stator comprises a stator base body with a stator longitudinal axis. The stator base body is preferably designed as a laminated core consisting of several coaxially stacked stator disks, for example, made of electrical steel. The stator disks are preferably electrically insulated from one another, for example, by means of baked enamel, paper, or the like. The stator disks are preferably pressed together. The stator slots are formed in the stator base body and have a slot depth in the radial direction, a slot width in the circumferential direction, and a slot length along the stator longitudinal axis.

[0027] The hairpins are arranged in the stator slots in a radial direction in several slot positions. The hairpins are preferably arranged in the stator slots such that one hairpin is arranged in each stator slot per slot position. The hairpins preferably have a hairpin width that corresponds to the slot width or is only slightly smaller than the slot width. Within the stator slot, the hairpins are preferably arranged directly next to one another and, if necessary, spaced from one another by an insulator, such as paper.

[0028] First hairpin ends arranged on the first stator end face of the stator base body protrude from the stator slots of the stator base body, are separated from each other, are at least partially set in pairs, and each have a first hairpin end of a different stator slot. Preferably, adjacent pairs of first hairpin ends in the stator slots are set in different circumferential directions.

[0029] The electric machine according to the invention provides all the advantages already described for a method for producing a stator for a motor according to the first aspect of the invention. Accordingly, the electric machine according to the invention has the advantage over conventional electric machines that the number of setting tools used is reduced using simple means and in a cost-effective manner by combining the first hairpin ends in pairs. In addition, the installation space required for the stator can be reduced by setting adjacent first hairpin ends together. Finally, after setting, the pairs of first hairpin ends have an increased distance from adjacent pairs of first hairpin ends, so that electrical insulation of the stator is improved and can be arranged more easily on the stator.

[0030] An electric machine according to the invention and a method according to the invention are explained in more detail below with reference to the drawings. They show schematically: Fig. 1 shows an exploded perspective view of an electric machine according to a preferred first embodiment of the invention, Fig. 2 shows a detailed view of a preferred embodiment of a stator during the winding process, and Fig. 3 shows a flow chart of a preferred embodiment of a method according to the invention.

[0031] Elements with the same function and mode of action are listed in the Fig. 1 to 3 are each provided with the same reference numerals.

[0032] In Fig. 1 schematically shows an electric machine 2 according to a preferred first embodiment of the invention in a perspective exploded view. The electric machine 2 has a stator 1, which is manufactured using a method according to the invention. The stator 1 has a stator base body 3, in which a plurality of stator slots 4 are formed. Several hairpins 5 are arranged next to one another in each of the stator slots 4. First hairpin ends 9 of the hairpins 5 are offset, with first hairpin ends 9 from different stator slots 4 being welded together in pairs. The hairpins 5 thus form a stator winding of the stator 1.

[0033] Furthermore, the electric machine 2 has a rotor 11 arranged coaxially with the stator 1 and a motor housing 12, which can be arranged around the stator 1 and can be closed in the axial direction via two housing covers 13 of the electric machine 2. To energize the stator winding, the electric machine 2 has power electronics 14, which is held on the motor housing 12 and electrically coupled to the stator winding.

[0034] Fig. 2 shows a preferred embodiment of a stator 1 during setting, schematically in a detailed view. This view shows part of the stator base body 3, which extends around the stator longitudinal axis L. Eight hairpins 5 are arranged in different slot positions in a stator slot 4. A hairpin 5 arranged closest to the stator longitudinal axis L is arranged in a first slot position 6. A hairpin 5 arranged furthest from the stator longitudinal axis L is arranged in a last slot position 8. The hairpins 5 arranged between the first slot position 6 and the last slot position 8 are arranged in inner slot positions 7. One hairpin 5 is arranged in each slot position of the stator slot 4.

[0035] First hairpin ends 9 of the hairpins 5 protrude from the stator slot 4 along the stator longitudinal axis L and are partially separated in the radial direction R. The first hairpin ends 9 of the hairpins 5 of the first slot layer 6 and the last slot layer 8 are each individually separated and each gripped by a setting tool 10. The first hairpin ends 9 of the hairpins 5 of the inner slot layer 7 are each separated in pairs and gripped in pairs by a common setting tool 10. Setting is carried out, for example, in such a way that the first hairpin end 9 of the first slot layer 6 is set into the drawing plane and, with the adjacent setting tools 10, is alternately set out of the drawing plane and into the drawing plane. The first hairpin end 9 of the last slot layer 8 is thus set back into the drawing plane.

[0036] In Fig.3, a preferred embodiment of a method according to the invention is shown schematically in a flow diagram. In a first method action 100, a stator base body 3 with stator slots 4 is provided. Several, for example eight, hairpins 5 are arranged in each of the stator slots 4. The hairpins 5 are arranged in the stator slots 4 in a first slot position 6, several inner slot positions 7, and a last slot position 8. Free first hairpin ends 9 of the hairpins 5 are - at least partially - separated from one another. In a second method action 200, two directly adjacent first hairpin ends 9 of the inner slot positions 7 are gripped with a common setting tool 10.

[0037] In a third process step 300, the first hairpin ends 9, which are jointly gripped by the common setting tool 10, are jointly set with the common setting tool 10. The setting preferably occurs such that adjacent setting tools 10 alternately set in different directions. In a fourth process step 400, the first hairpin ends 9 of different stator slots 4 are welded in pairs using a welding device. This forms a stator winding. List of reference symbols 1 stator 2 electric machine 3 Stator base body 4 Stator slot 5 Hairpin 6 first groove layer 7 inner groove position 8 last groove layer 9 first hairpin end 10 setting tools 11 Rotor 12 engine housing 13 Housing cover 14 Power electronics 100 first procedural action 200 second procedural action 300 third procedural action 400 fourth procedural action L Stator longitudinal axis R radial direction 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 2018 206 004 A1

[0003] DE 10 2019 211 713 A1

[0004] US 2018 / 375 409 A1

[0004]

Claims

[1] Method for producing a stator (1) for an electric machine (2), comprising: - Providing a stator base body (3) with stator slots (4), wherein hairpins (5) are arranged in the stator slots (4), wherein the hairpins (5) are arranged in a first slot position (6), several inner slot positions (7) and a last slot position (8) in the stator slots (4), wherein free first hairpin ends (9) of the hairpins (5) protrude from the stator base body (3), - gripping two first hairpin ends (9) directly adjacent in the radial direction (R) with a common setting tool (10), - Joint setting of the first hairpin ends (9) with the common setting tool (10), and - Welding the first hairpin ends (9) of different stator slots (4) with a welding device. [2] Method according to claim 1, characterized bythat the first hairpin end (9) of the first groove layer (6) and / or the first hairpin end (9) of the last groove layer (8) is individually gripped and set with a separate setting tool (10). [3] Method according to claim 1 or 2, characterized by that the first hairpin ends (9) of the inner groove layers (7) are gripped and set together in pairs using a common setting tool (10). [4] Method according to at least one of the preceding claims, characterized bythat a stator base body (3) is provided, in which free second hairpin ends of the hairpins (5) protrude from the stator base body (3), wherein the first hairpin ends (9) and the second hairpin ends are formed at opposite ends of the hairpins (5), wherein two second hairpin ends directly adjacent in the radial direction (R) are gripped with a common setting tool (10) and set together, and wherein the second hairpin ends of different stator slots (4) are welded with the welding device. [5] Method according to claim 4, characterized by that the second hairpin end of the first groove layer (6) and / or the last groove layer (8) is individually gripped and set with its own setting tool (10). [6] Method according to claim 4 or 5, characterized bythat the second hairpin ends of the inner groove layers (7) are gripped and set together in pairs using a common setting tool (10). [7] Method according to at least one of the preceding claims, characterized by that the stator base body (3) is provided with eight hairpins (5) per stator slot (4), wherein five setting tools (10) are used, wherein the first hairpin ends (9) of the outer slot layers (8) are each gripped and set with one of the setting tools (10) and the first hairpin ends (9) of adjacent inner slot layers (7) are each gripped and set in pairs with one of the setting tools (10). [8] Method according to at least one of the preceding claims, characterized by that the first hairpin ends (9) gripped in pairs by means of one of the setting tools (10) are separated from one another in the radial direction (R). [9] Method according to claim 8, characterized bythat the first hairpin end (9) located further inside in the radial direction (R) is shaped in the direction of a stator longitudinal axis (L) of the stator base body (3) and / or the first hairpin end (9) located further outside in the radial direction (R) is shaped away from the stator longitudinal axis (L). [10] Electric machine (2), comprising a stator (1) and a rotor (11) arranged coaxially to the stator (1), characterized by that the stator (1) is manufactured by a method according to one of the preceding claims.

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