Method for producing stator of electric machine and electric machine

Abstract

The invention relates to a method for producing a stator (1) of an electric machine (2), comprising: providing a stator base body (3) having stator slots (4), in which stator slots (4) there are arranged hairpin lines (5), the hairpin lines (5) being arranged in the stator slots (4) in a first slot layer (6), a plurality of inner slot layers (7) and a last slot layer (8), the free first hairpin wire ends (9) of the hairpin wire (5) are separated from each other,-clamping two directly adjacent first hairpin wire ends (9) by means of a common bending tool (10),-jointly bending the first hairpin wire ends (9) by means of the common bending tool (10), and-welding the first hairpin wire ends (9) of the different stator slots (4) in pairs by means of a welding device. The invention also relates to an electric machine (2), in particular for a motor vehicle.

Description

Technical Field

[0001] The invention relates to a method for producing a stator of an electric machine, in particular for a motor vehicle. The invention also relates to an electric machine, in particular for a motor vehicle, having a stator and a rotor arranged coaxially with the stator. Background Art

[0002] A method for producing a stator for an electric motor is known, wherein the stator base body of the stator is filled with a plurality of hairpins (or hairpin winding wires). For this purpose, the stator base body has a plurality of stator slots in which the hairpins are arranged one above the other in a radial direction, so that a first free hairpin end of the hairpin protrudes in an axial direction at a first stator end side of the stator and a second free hairpin end of the hairpin protrudes in an axial direction at a second stator end side of the stator opposite to the first stator end side. Alternatively, the hairpin can also be provided as a U-shaped wire (U-Pin), so that only a hairpin bend of the hairpin is arranged at the second stator end side.

[0003] The free hairpin ends are then distributed in the radial direction. This process is also called "expansion". Patent document DE 10 2018 206 004 A1 shows a device and method for expanding the ends of a hairpin.

[0004] After expansion, bend the free ends of the hairpin in the radial direction In order to orient the hairpin ends to be welded to each other relative to each other. Devices and methods for bending hairpin ends are known from patent documents DE 10 2019 211 713 A1 and US 2018 / 375 409 A1. For this purpose, the free hairpin ends are clamped in a bending tool and bent in such a way that radially adjacent hairpin ends of the stator slots are bent in different directions.

[0005] A disadvantage of the known methods for producing stators is that a separate numerically controlled bending tool is required for the bending of each wire layer in the stator slot. This leads to increased manufacturing costs. In addition, a stator with hairpin wire ends that are bent alternately in different directions requires more construction space. Finally, the hairpin wire ends are usually arranged closely adjacent to each other after the bending, so that additional or particularly complex electrical insulation is required to avoid short circuits during operation of the electric machine. Summary of the invention

[0006] The technical problem to be solved by the present invention is therefore to eliminate or at least partially eliminate the above-mentioned disadvantages in a method for producing a stator of an electric machine, in particular an electric machine for a motor vehicle, and in an electric machine, in particular an electric machine for a motor vehicle. The technical problem of the present invention is in particular to provide a method and an electric machine which have an improved production process in a simple and cost-effective manner, for example by avoiding excessive tool requirements and / or reducing the construction space requirement and / or improving the insulation.

[0007] Accordingly, the technical problem is solved by a method for producing a stator of an electric machine and by an electric machine. Further features and details of the invention are apparent from the description and the drawings. The features and details described here in connection with the method according to the invention are of course also applicable in connection with the electric machine according to the invention, and vice versa, so that the individual inventive aspects always refer to each other or can refer to each other in terms of the disclosure.

[0008] According to a first aspect of the invention, the technical problem is solved by a method for producing a stator for an electric machine, in particular a stator for an electric machine of a motor vehicle. The method comprises:

[0009] - providing a stator base body with stator slots, wherein hairpins are arranged in the stator slots, wherein the hairpins are arranged in the stator slots in a first slot layer, in a plurality of inner slot layers and in a last slot layer, wherein a free first hairpin end of the hairpin protrudes from the stator base body,

[0010] - clamping two first hairpin ends directly adjacent to each other in the radial direction by a common bending tool,

[0011] - bending the first hairpin wire ends together by a common bending tool, and

[0012] - Welding the first hairpin wire ends of different stator slots by means of a welding device.

[0013] First, a stator base body with a stator longitudinal axis is provided. The stator base body is preferably designed as a laminated core, which consists of a plurality of coaxially stacked stator plates, which are composed of electrical steel sheets, for example. The stator plates are preferably electrically insulated from each other, for example by baking varnish, paper or similar materials. The stator plates are preferably pressed against each other. 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.

[0014] The hairpins are arranged in the stator slots in a plurality of slot layers along the radial direction. Within the scope of the present invention, the slot layer closest to the longitudinal axis of the stator is referred to as the "first slot layer". Within the scope of the present invention, the slot layer farthest from the longitudinal axis of the stator is referred to as the "last slot layer". Within the scope of the present invention, the slot layers arranged between the first slot layer and the last slot layer are referred to as "inner slot layers". The hairpins are preferably arranged in the stator slots in such a way that one hairpin is arranged for each slot layer in each stator slot. The hairpin winding preferably has a hairpin width that corresponds to the slot width or is only slightly smaller than the slot width.

[0015] The free first hairpin wire ends arranged at the first stator end side of the stator base body extend out of the stator base body. The first hairpin wire ends are preferably separated from each other. This means that the hairpin wires are deformed in the radial direction so that the first hairpin wire ends adjacent in the radial direction of the stator slots have a greater distance from each other than in the stator slots. Inside the stator slots, the hairpin wires are preferably arranged directly adjacent (or side by side) and, if necessary, spaced apart from each other by an insulator such as paper.

[0016] For example, two first hairpin wire ends directly adjacent to each other in the radial direction are clamped by a bending tool by pushing and sleeve the bending tool, closing the clamping jaws of the bending tool, etc. Thus, two first hairpin wire ends of adjacent slot layers are clamped. The other first hairpin wire ends of the same two slot layers are preferably clamped by the same bending tool. For example, the pushing and sleeve can be performed along the longitudinal extension of the first hairpin wire end or transverse to the longitudinal extension. The bending tool can, for example, have a bending crown or a similar device. Preferably, the other two first hairpin wire ends directly adjacent to each other in the radial direction are clamped by other bending tools respectively.

[0017] The first hairpin wire ends clamped together are bent together in one direction by the movement of the bending tool along the circumferential direction of the stator matrix. The other first hairpin wire ends of the same two slot layers are preferably bent in the same direction by the same bending tool. The other first hairpin wire ends clamped in pairs are preferably bent together in one direction by the corresponding bending tools. It is preferred that the adjacent pairs of the first hairpin wire ends in the stator slots are bent along different circumferential directions. This makes it possible to achieve a particularly compact construction of the stator.

[0018] Finally, the first hairpin wire ends of different stator slots are welded in pairs by a welding device. Preferably, the pairs of first hairpin wire ends adjacent in the radial direction that are bent together by a bending tool are not welded to each other, but are preferably welded to other first hairpin wire ends adjacent in the radial direction. This forms an electrical conductor that extends through the stator matrix at least twice. If the hairpin wire is provided as a U-shaped wire, continuous electrical conductors are formed in this way, which extend through the stator matrix more times.

[0019] Compared to conventional methods, the method according to the invention for producing a stator of an electric machine has the advantage that the number of bending tools used is reduced by combining the first hairpin ends in pairs in a simple and cost-effective manner. In addition, by bending adjacent first hairpin ends together, the construction space requirement for the stator can be reduced. Finally, after the bending, the pairs of first hairpin ends have an increased distance from the adjacent pairs of first hairpin ends, so that the electrical insulation of the stator is improved or the electrical insulation can be arranged more easily at the stator.

[0020] According to the preferred extended design of the present invention, it can be provided in a method that the first hairpin end of the first slot layer and / or the first hairpin end of the last slot layer are clamped and bent separately by respective bending tools. It is preferred that the bending direction of the first hairpin end of the first slot layer and / or the first hairpin end of the last slot layer is opposite to the bending direction of the adjacent first hairpin end. Multiple or all first hairpin ends of the first slot layer are preferably clamped and bent by respective bending tools. It is further preferred that multiple or all first hairpin ends of the last slot layer are clamped and bent by respective bending tools. Therefore, it is preferred that the first hairpin end of the first slot layer is clamped and bent by the first bending tool, and the first hairpin end of the last slot layer is clamped and bent by the last bending tool. This has the advantage that the full utilization of the existing construction space is improved by simple measures and in a cost-effective manner. A particularly compact construction form of the stator can be achieved thereby. In addition, the electrical insulation of the stator can be further improved thereby.

[0021] According to the present invention, it is preferred that the first hairpin wire ends of the inner slot layer are clamped and bent to each other in pairs by a common bending tool. The first hairpin wire ends of all inner slot layers are preferably clamped and bent to each other in pairs by a common bending tool. Adjacent pairs of first hairpin wire ends are preferably bent in opposite directions. By bending in pairs along different directions, a particularly large distance can be generated between adjacent first hairpin wire ends with different bending directions. This has the advantage that the full utilization of the existing construction space is improved by simple measures and in a cost-effective manner. A particularly compact construction form of the stator can be achieved thereby. In addition, the electrical insulation of the stator can be further improved thereby.

[0022] It is further preferred to provide the following stator matrix, wherein the free second hairpin wire end of the hairpin wire extends from the stator matrix, wherein the first hairpin wire end and the second hairpin wire end are constructed at the opposite ends of the hairpin wire, wherein the two second hairpin wire ends directly adjacent in the radial direction are clamped by a common bending tool and bent together, and wherein the second hairpin wire ends of different stator slots are welded by a welding device. In other words, it is preferred to use a hairpin wire designed as a so-called I-shaped wire. The U-shaped wire has two first hairpin wire ends each extending from the first stator end side of the stator matrix, while the I-shaped wire has a first hairpin wire end and a second hairpin wire end, wherein the first hairpin wire end extends from the first stator end side, and the second hairpin wire end extends from the second stator end side. In order to manufacture the stator winding, it is necessary to bend and weld the hairpin wire on the two stator end sides for the I-shaped wire. It is preferred to use the U-shaped wire and the I-shaped wire in combination, wherein the number of the U-shaped wires is preferably greater than the number of the I-shaped wires. Preferably, an I-shaped wire is used to connect the electric machine to the power electronics on one side of the stator, on which the U-shaped wire is bent by approximately 180°. This has the advantage that the available installation space can be utilized more efficiently by simple measures and in a cost-effective manner. This makes it possible to achieve a particularly compact design of the stator. Furthermore, the electrical insulation of the stator can be further improved as a result.

[0023] In a particularly preferred design of the present invention, it can be provided in a method that the second hairpin wire ends of the first slot layer and / or the last slot layer are clamped and bent separately by respective bending tools. It is preferred that the bending direction of the second hairpin wire ends of the first slot layer and / or the second hairpin wire ends of the last slot layer is opposite to the bending direction of the adjacent second hairpin wire ends. This has the advantage that the full utilization of the existing construction space is improved by simple measures and in a cost-effective manner. This makes it possible to achieve a particularly compact construction form of the stator. In addition, the electrical insulation of the stator can be further improved.

[0024] The second hairpin wire ends of the inner slot layer are preferably clamped and bent to each other in pairs by a common bending tool. The second hairpin wire ends of all inner slot layers are preferably clamped and bent to each other in pairs by a common bending tool. Adjacent pairs of second hairpin wire ends are preferably bent in opposite directions. By bending in pairs along different directions, a particularly large distance can be generated between adjacent second hairpin wire ends with different bending directions. This has the advantage that the full utilization of the existing construction space is improved by simple measures and in a cost-effective manner. A particularly compact construction form of the stator can be achieved thereby. In addition, the electrical insulation of the stator can be further improved thereby.

[0025] According to a preferred embodiment of the present invention, a stator matrix having eight hairpins for each stator slot is provided, wherein five bending tools are used, wherein the first hairpin ends of the outer slot layer are clamped and bent by one of the bending tools, respectively, and the first hairpin ends of the adjacent inner slot layer are clamped and bent in pairs by one of the bending tools. Alternatively, a stator matrix having four hairpins for each stator slot can be provided, wherein three bending tools are used. In this case, the first hairpin ends of the outer slot layer are clamped and bent by one of the bending tools, respectively, and the two first hairpin ends of the inner slot layer are clamped and bent in pairs by one of the bending tools. Alternatively, a stator matrix having six hairpins for each stator slot can be provided, wherein four bending tools are used. In this case, the first hairpin ends of the outer slot layer are clamped and bent by one of the bending tools, respectively, and the first hairpin ends of the adjacent inner slot layer are clamped and bent in pairs by one of the bending tools. This has the advantage that a stator having a particularly compact and economically expedient design can be produced by simple measures and in a cost-effective manner.

[0026] The first hairpin wire ends clamped in pairs by means of one of the bending tools are particularly preferably separated from each other in the radial direction. The separation is preferably performed as follows so that the distance between the corresponding first hairpin wire ends in the radial direction increases. According to this preferred embodiment, the separation is performed after bending together. According to the present invention, it is preferred that the first hairpin wire ends of the hairpin wires located further outward in the radial direction are bent outward in the radial direction, and / or the first hairpin wire ends of the hairpin wires located further in the radial direction are bent inward in the radial direction. This has the advantage that the full utilization of the existing construction space is improved by simple measures and in a cost-effective manner. A particularly compact construction form of the stator can thereby be achieved.

[0027] According to the present invention, it is further preferred that the first hairpin end located further inside in the radial direction is formed in the direction of the stator longitudinal axis of the stator base body, and / or the first hairpin end located further outside in the radial direction is formed away from the stator longitudinal axis. It is particularly preferred that the first hairpin end located further inside is formed toward the stator longitudinal axis, and the first hairpin end located further outside in the radial direction is formed away from the stator longitudinal axis. This has the advantage that the full utilization of the existing construction space is improved by simple measures and in a cost-effective manner. This makes it possible to achieve a particularly compact construction of the stator.

[0028] According to a second aspect of the invention, the technical problem is solved by an electric machine, in particular an electric machine 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 produced by the method according to the invention.

[0029] Accordingly, the stator has a stator base body having a stator longitudinal axis. The stator base body is preferably designed as a laminated core, which consists of a plurality of coaxially stacked stator plates, which are composed, for example, of electrical steel sheets. The stator plates are preferably electrically insulated from one another, for example by baking varnish, paper or the like. The stator plates are preferably pressed against one another. 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.

[0030] The hairpins are arranged in the stator slots in a plurality of slot layers along the radial direction. The hairpins are preferably arranged in the stator slots in such a way that one hairpin is arranged in each stator slot for each slot layer. The hairpins preferably have a hairpin width that corresponds to the slot width or is only slightly smaller than the slot width. The hairpins are preferably arranged directly adjacent to each other in the stator slots and, if necessary, are spaced apart from each other by an insulator such as paper.

[0031] The first hairpin wire ends arranged at the first stator end side of the stator base body extend out of the stator slot of the stator base body, the first hairpin wire ends are separated from each other, at least partially bent in pairs and bent together with each first hairpin wire end of another stator slot. The adjacent pairs of the first hairpin wire ends in the stator slot are preferably bent along different circumferential directions.

[0032] All the advantages already described with respect to the method for manufacturing a stator according to the first aspect of the invention are achieved in the motor according to the invention. Accordingly, the motor according to the invention has the advantage, compared to conventional motors, that the number of bending tools used is reduced by combining the first hairpin ends in pairs by simple measures and in a cost-effective manner. In addition, the construction space requirement for the stator can be reduced by bending adjacent first hairpin ends together. Finally, after the bending, the pair of first hairpin ends has an increased distance from the adjacent pair of first hairpin ends, so that the electrical insulation of the stator is improved or the electrical insulation can be arranged more easily at the stator. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The electric machine according to the invention and the method according to the invention are explained in more detail below with reference to the accompanying drawings. In the drawings:

[0034] Figure 1 An electric machine according to a preferred first embodiment of the present invention is shown in a perspective exploded view;

[0035] Figure 2 A preferred embodiment of the stator is shown in a detail view during bending; and

[0036] Figure 3 A flow chart shows a preferred specific embodiment of the method according to the invention.

[0037] exist Figures 1 to 3 In the drawings, elements having the same function and operating principle are respectively provided with the same reference numerals. DETAILED DESCRIPTION

[0038] exist Figure 1 Schematically, an electric motor 2 according to a preferred first embodiment of the present invention is shown in a three-dimensional exploded view. The electric motor 2 has a stator 1, which is manufactured by means of a method according to the present invention. The stator 1 has a stator base body 3, in which a plurality of stator slots 4 are formed. A plurality of hairpins 5 are arranged adjacent to each other in the stator slots 4. The first hairpin ends 9 of the hairpins 5 are bent, wherein the first hairpin ends 9 of different stator slots 4 are welded to each other in pairs. The hairpins 5 thus form the stator winding of the stator 1.

[0039] Furthermore, the electric motor 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 by two housing covers 13 of the electric motor 2. In order to energize the stator winding, the electric motor 2 has power electronics 14 which are held on the motor housing 12 and are electrically coupled to the stator winding.

[0040] Figure 2A preferred embodiment of the stator 1 during bending is schematically shown in a detail view. A portion of a stator base body 3 is shown in this view, which extends around the stator longitudinal axis L. Eight hairpins 5 are arranged in the stator slots 4 in different slot layers. The hairpins 5 arranged closest to the stator longitudinal axis L are arranged in the first slot layer 6. The hairpins 5 arranged farthest from the stator longitudinal axis L are arranged in the last slot layer 8. The hairpins 5 arranged between the first slot layer 6 and the last slot layer 8 are arranged in the inner slot layer 7. A hairpin 5 is arranged in each slot layer of the stator slot 4.

[0041] The first hairpin ends 9 of the hairpins 5 protrude from the stator slots 4 along the stator longitudinal axis L and are partially separated along 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 separated individually and clamped by bending tools 10 respectively. The first hairpin ends 9 of the hairpins 5 of the inner slot layer 7 are separated in pairs and clamped in pairs by a common bending tool 10. The bending is achieved, for example, in such a way that the first hairpin ends 9 of the first slot layer 6 are bent into the drawing surface and are alternately bent out of the drawing surface and bent into the drawing surface by adjacent bending tools 10. As a result, the first hairpin ends 9 of the last slot layer 8 are bent back into the drawing surface.

[0042] exist Figure 3 Schematically shown in the flowchart of a preferred embodiment of the method according to the present invention. In a first method step 100, a stator base body 3 having stator slots 4 is provided. A plurality of, for example, eight, hairpins 5 are arranged in the stator slots 4. The hairpins 5 are arranged in the stator slots 4 in the first slot layer 6, in a plurality of inner slot layers 7 and in the last slot layer 8. The free first hairpin ends 9 of the hairpins 5 are at least partially separated from each other. In a second method step 200, two directly adjacent first hairpin ends 9 of the inner slot layer 7 are clamped by a common bending tool 10.

[0043] In the third method step 300, the first hairpin wire ends 9 clamped together by the common bending tool 10 are bent together by the common bending tool 10. The bending is preferably performed in such a way that adjacent bending tools 10 bend alternately in different directions. In the fourth method step 400, the first hairpin wire ends 9 of different stator slots 4 are welded in pairs by a welding device. The stator winding is thus formed.

[0044] Reference numerals list

[0045] 1 Stator

[0046] 2 Motor

[0047] 3. Stator matrix

[0048] 4 stator slots

[0049] 5 Card issuing line

[0050] 6First slot layer

[0051] 7 internal slot layers

[0052] 8 Final slot layer

[0053] 9 End of the first hairpin line

[0054] 10 Bending tools

[0055] 11 Rotors

[0056] 12 Motor housing

[0057] 13 Shell cover

[0058] 14 Power Electronic Devices

[0059] 100 First Method Steps

[0060] 200 Second method step

[0061] 300 Third Method Step

[0062] 400 Fourth Method Step

[0063] L stator longitudinal axis

[0064] R radial direction

Claims

1. A method for producing a stator (1) of an electric machine (2), the method comprising: - a stator base body (3) having stator slots (4) is provided, wherein: A hairpin (5) is arranged in the stator slot (4), wherein the hairpin (5) is arranged in the stator slot (4) in a first slot layer (6), in a plurality of inner slot layers (7) and in a last slot layer (8), wherein a free first hairpin end (9) of the hairpin (5) protrudes from the stator base body (3), - clamping two first hairpin ends (9) directly adjacent to each other in the radial direction (R) by means of a common bending tool (10), - jointly bending the first hairpin ends (9) by means of a common bending tool (10), and - Welding the first hairpin ends (9) of the different stator slots (4) by means of a welding device.

2. The method according to claim 1, It is characterized in that The first hairpin end (9) of the first slot layer (6) and / or the first hairpin end (9) of the last slot layer (8) are clamped and bent individually by respective bending tools (10).

3. The method according to claim 1 or 2, It is characterized in that The first hairpin ends (9) of the inner groove layer (7) are clamped and bent in pairs by a common bending tool (10).

4. The method according to at least one of the preceding claims, It is characterized in that A stator base body (3) is provided, wherein a free second hairpin end of a hairpin (5) extends from the stator base body (3), wherein a first hairpin end (9) and a second hairpin end are constructed at opposite ends of the hairpin (5), wherein two second hairpin ends directly adjacent in a radial direction (R) are clamped by a common bending tool (10) and bent together, and wherein the second hairpin ends of different stator slots (4) are welded by a welding device.

5. The method according to claim 4, It is characterized in that The second hairpin cord end of the first slot layer (6) and / or the second hairpin cord end of the last slot layer (8) are clamped and bent individually by respective bending tools (10).

6. The method according to claim 4 or 5, It is characterized in that The second hairpin wire ends of the inner groove layer (7) are clamped and bent in pairs by a common bending tool (10).

7. The method according to at least one of the preceding claims, It is characterized in that A stator base body (3) having eight hairpins (5) for each stator slot (4) is provided, wherein five bending tools (10) are used, wherein the first hairpin ends (9) of the outer slot layers (8) are clamped and bent by one of the bending tools (10), and the first hairpin ends (9) of the adjacent inner slot layers (7) are clamped and bent in pairs by one of the bending tools (10).

8. The method according to at least one of the preceding claims, It is characterized in that The first hairpin ends (9) clamped in pairs by one of the bending tools (10) are separated from each other along the radial direction (R).

9. The method according to claim 8, It is characterized in that The first hairpin end (9) located further inwardly along the radial direction (R) is formed along the direction of the stator longitudinal axis (L) of the stator base body (3), and / or the first hairpin end (9) located further outwardly along the radial direction (R) is formed away from the stator longitudinal axis (L).

10. An electric machine (2), comprising a stator (1) and a rotor (11) arranged coaxially with the stator (1), It is characterized in that The stator (1) is produced by a method according to one of the preceding claims.

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