Holding device for hairpin and method for producing hairpin stator

Abstract

The invention relates to a holding device for holding a hairpin end region of a hairpin of a hairpin stator of an electric machine of a motor vehicle for a welding process, in which the hairpin is arranged in a radial direction from outside to inside with a first hairpin layer, a second hairpin layer, a third hairpin layer and a fourth hairpin layer, the retaining device has an outer ring for circumferentially surrounding the hairpin end region and at least one first inner ring which is designed separately from the outer ring and is arranged within the outer ring in such a way that the hairpin end regions of the first and second hairpin layers are arranged between the outer ring and the first inner ring, wherein the outer ring and the first inner ring are designed, in the assembled state, to form recesses for accommodating in pairs the hairpin end regions of the first and second hairpin layers, respectively, and wherein the outer ring has a first alignment device for alignment with respect to the stator base body of the hairpin stator, and a second alignment device for alignment with respect to the stator base body of the hairpin stator, the outer ring and the first inner ring are configured to be continuously arranged on the stator base body.

Description

Technical Field

[0001] The invention relates to a holding device for holding a hairpin end region of a hairpin of a hairpin stator of an electric motor of a motor vehicle for a welding process. The invention also relates to a method for producing a hairpin stator of an electric motor of a motor vehicle. Background Art

[0002] A clamping device is known in which the fixed hairpin end regions of the hairpins of a hairpin stator are joined in pairs and held together for a subsequent welding process. The clamping device has a plurality of recesses for accommodating the hairpin end regions in pairs and is designed to be placed as a complete unit on the stator base body of the hairpin stator in the axial direction in such a way that the hairpin end regions engage in pairs in the recesses and protrude again from the recesses.

[0003] In principle, a distinction should be made between a number of different tensioning concepts. In a radial tensioning concept, the hairpin end region is tensioned in the radial direction against a fixed stop. In this case, no targeted alignment of the hairpin end region in the tangential direction takes place. In a tangential tensioning concept, the hairpin end regions are tensioned against each other in the tangential direction, wherein no targeted alignment of the hairpin end regions in the radial direction takes place. Furthermore, mixed tensioning concepts are also known, in which the hairpin end regions are tensioned in the radial direction and in the tangential direction.

[0004] Document DE 10 2017 123 670 A1 discloses a device and a method for aligning the hairpin end regions of a hairpin of an electric machine. The device has a plurality of tensioning jaws that can be adjusted in the radial direction on a support configured as a gear in order to thereby fix the hairpin end regions in pairs. Document DE 10 2021 129 436 A1 discloses a system and a method for fastening a hairpin for connection by welding. The system has a plurality of ring segments that can be moved relative to each other in the radial direction in order to align the hairpin end regions to be welded.

[0005] Known tensioning devices have the disadvantage that they usually require a very complex mechanism and the investment costs can be very high. In addition, such mechanisms have a relatively high complexity with many individual components, which makes susceptibility to failure very high and maintenance particularly cumbersome. Finally, many tensioning devices have the problem that, when removing the tensioning device, welding burrs can get stuck at the edges of the recess, thereby increasing the resistance during removal and the wear of the tensioning device. In addition, this can damage the welded connection. Summary of the invention

[0006] The object of the present invention is therefore to eliminate or at least partially eliminate the above-described disadvantages in a holding device for holding the hairpin end regions of a hairpin of a hairpin stator of an electric machine for a welding process. In particular, the object of the present invention is to create a holding device and a method for producing a hairpin stator of an electric machine for a motor vehicle, which ensure in a simple and cost-effective manner that the hairpin end regions are held together in pairs and / or can be easily removed from the hairpin end regions welded to each other.

[0007] The above-mentioned object is achieved by the patent claims. The object is therefore achieved by a holding device for a hairpin end region of a hairpin for holding a hairpin stator of an electric motor of a motor vehicle for a welding process, having the features of independent claim 1, and by a method for producing a hairpin stator of an electric motor of a motor vehicle, having the features of parallel claim 10. Further features and details of the invention are derived from the dependent claims, the description and the drawings. Here, of course, the features and details described in conjunction with the holding device according to the invention also apply in conjunction with the method according to the invention, and vice versa, respectively, so that with respect to the disclosure of the individual inventive aspects, reference is always made to one another or can be made to one another.

[0008] According to a first aspect of the invention, the object is solved by a holding device for holding a hairpin end region of a hairpin of a hairpin stator of an electric motor of a motor vehicle for a welding process. The hairpin of the hairpin stator is arranged in a radial direction from the outside to the inside with a first hairpin layer, a second hairpin layer, a third hairpin layer and a fourth hairpin layer. The holding device has an outer ring for circumferentially surrounding the hairpin end region and at least one first inner ring configured separately from the outer ring for being arranged in the outer ring so that the hairpin end regions of the first hairpin layer and the second hairpin layer are arranged between the outer ring and the first inner ring. The outer ring and the first inner ring are configured to form recesses for accommodating the hairpin end regions of the first hairpin layer and the second hairpin layer in pairs in the assembled state, wherein the outer ring has a first alignment device for alignment relative to the stator base body of the hairpin stator. The outer ring and the first inner ring are configured to be arranged continuously at the stator base body.

[0009] The holding device is designed to hold the hairpin end regions of the hairpins of the hairpin stator together in pairs, which can be designed, for example, as I-shaped pins or U-shaped pins, so that the hairpin end regions can be connected to each other in a materially bonded and electrically conductive manner via a welding device, such as a laser welding device. In this case, usually only the fixed ends of the hairpin end regions are welded. In this way, a multi-phase stator winding can be produced by hairpins welded to each other.

[0010] The hairpins are arranged in stator slots of the stator base body of the hairpin stator and protrude from the stator base body in the axial direction. The hairpins are arranged in the stator slots in a plurality of hairpin layers. The outer hairpin layer farthest from the stator longitudinal axis is called the first hairpin layer. The next hairpin layer toward the stator longitudinal axis is the second hairpin layer, the third hairpin layer and the fourth hairpin layer. It is also possible to arrange other hairpin layers toward the stator longitudinal axis, such as the fifth hairpin layer and the sixth hairpin layer or also the seventh hairpin layer and the eighth hairpin layer in addition.

[0011] The outer ring of the retaining device is configured to be arranged at the stator base so that the hairpin end regions of all hairpin layers (i.e., the first hairpin layer, the second hairpin layer, the third hairpin layer and the fourth hairpin layer and possible additional hairpin layers) are arranged in the outer ring. For example, in this state, the hairpin end region of the first hairpin layer can contact the outer ring. The outer ring is preferably made of steel. Further preferably, the outer ring has a surface with good tribological properties to ensure that the hairpin end region slides away with as little friction as possible at the outer ring, for example when the outer ring is arranged or removed from the stator base. For example, the surface can be polished. The outer ring is configured to be arranged separately from the first inner ring at the stator base, preferably before the first inner ring is arranged at the stator base.

[0012] In order to ensure a defined alignment of the outer ring relative to the stator base body, the outer ring has a first alignment device. For example, the first alignment device can be configured as a shoulder.

[0013] The first inner ring is arranged separately from the outer ring and is configured to be arranged at the outer ring, preferably when the outer ring is already arranged at the stator base. The first inner ring has an average diameter that is smaller than the average diameter of the outer ring. Preferably, the outer ring and the first inner ring are configured so that the first inner ring can be arranged in the outer ring in a form-fitting manner. The first inner ring and the outer ring are configured to form a plurality of recesses in a state of being joined together (i.e., in a state where the first inner ring is arranged in the outer ring).

[0014] The individual recesses are preferably each partially delimited laterally by the outer ring and each partially by the first inner ring. Preferably, the recesses are thus each completely delimited. The recesses are each designed to accommodate two hairpin end regions to be welded to one another, wherein the hairpin end region of the first hairpin layer and the hairpin end region of the second hairpin layer can each be held together in the recess. Preferably, the first inner ring is designed in such a way that when the first inner ring is arranged on the stator base body, the hairpin end region is pressed into the recess via the first inner ring with the outer ring already arranged there. The recess is designed in such a way that the two hairpin end regions are arranged side by side for welding, for example in a mutually contacting manner or with a marginal gap formed.

[0015] The holding device is preferably configured to accommodate the hairpin end regions of the first and second hairpin layers in pairs in the recesses in such a way that the free ends of the hairpin end regions protrude from the recess in the axial direction for welding. Preferably, the holding device is further configured to accommodate the hairpin end regions of the third and fourth hairpin layers in pairs in the recesses in such a way that the free ends of the hairpin end regions protrude from the recess in the axial direction for welding. Further preferably, the holding device is configured to arrange the hairpin end regions of possible further hairpin layers in a similar manner.

[0016] Compared to conventional retaining devices, the retaining device according to the invention has the advantage that the retention of the hairpin end region for welding is ensured by simple means and in a cost-effective manner. The retaining device has a particularly strong and simple design and can therefore be easily manufactured. Furthermore, due to the multi-part design of the retaining device, the stator base body can be demoulded particularly easily after the welding process by, for example, firstly removing the first inner ring and then the outer ring in the axial direction from the stator base body. Thus, compared to conventional retaining devices, curling at welding burrs and damage to the welded connection can be avoided better.

[0017] According to a preferred improvement of the present invention, it can be arranged in the retaining device that the first alignment device is configured to align the outer ring in the axial direction and the radial direction relative to the stator base body. Preferably, the first alignment device has a shoulder. Alternatively, the first alignment device may also have a chamfer. Via the shoulder or chamfer, a predefined radial position of the outer ring relative to the stator base body, such as a coaxial arrangement, can be ensured. In addition, the shoulder and the chamfer serve as a stop so that the relative position of the outer ring relative to the stator base body in the axial direction is limited and thus precisely defined. This has the advantage that the arrangement of the retaining device at the stator base body and the precise positional retention of the hairpin end area for welding are improved by simple means and in a cost-effective manner.

[0018] According to the present invention, it is preferred that the outer ring has a second alignment device for axially aligning the first inner ring relative to the outer ring. Therefore, via the second alignment device, the relative axial position of the first inner ring relative to the outer ring can be defined. Preferably, the second alignment device has a shoulder. Alternatively, the second alignment device can also have a chamfer. Via the shoulder or chamfer, a predefined radial position of the outer ring relative to the stator base body, such as a coaxial arrangement, can be ensured. In addition, the shoulder and the chamfer serve as a stop, so that the relative position of the first inner ring relative to the outer ring in the axial direction is limited and thus precisely defined. This has the advantage that the arrangement of the retaining device at the stator base body and the precise retention of the position of the hairpin end area for welding are improved by simple means and in a cost-effective manner.

[0019] Further preferably, the holding device has a second inner ring for being arranged in the first inner ring so that the hairpin end regions of the third hairpin layer and the fourth hairpin layer are arranged between the first inner ring and the second inner ring, wherein the first inner ring and the second inner ring are configured to form recesses for accommodating the hairpin end regions of the third hairpin layer and the fourth hairpin layer in pairs in the assembled state. The second inner ring is preferably configured separately from the outer ring and the first inner ring. Preferably, the second inner ring is configured to be arranged separately from the first inner ring at the stator base body, preferably when the outer ring is already arranged at the stator base body and the first inner ring is arranged in the outer ring. The second inner ring has an average diameter that is smaller than the average diameter of the first inner ring. Preferably, the first inner ring and the second inner ring are configured so that the second inner ring can be arranged in the first inner ring in a form-fitting manner. The second inner ring and the first inner ring are configured to form a plurality of recesses in the assembled state (ie, in a state in which the second inner ring is arranged in the first inner ring). The individual recesses are preferably partially limited laterally by the first inner ring and partially by the second inner ring, respectively. Preferably, the recesses are thus completely limited, respectively. The recesses are respectively configured to accommodate two hairpin end regions to be welded to each other, wherein the hairpin end region of the third hairpin layer and the hairpin end region of the fourth hairpin layer can be held together in the recesses. Preferably, the second inner ring is configured so that when the second inner ring is arranged on the stator base body, the hairpin end region is pressed into the recess via the second inner ring using the first inner ring already arranged there. According to the invention, for example, a third inner ring can also be provided, which behaves relative to the second inner ring as the second inner ring behaves relative to the first inner ring. Further preferably, a fourth inner ring can also be provided, which behaves relative to the third inner ring as the third inner ring behaves relative to the second inner ring. This has the advantage that the arrangement of the holding device on the stator base body and thus the positionally accurate holding of the hairpin end regions for welding are improved by simple means and in a cost-effective manner.

[0020] In a particularly preferred embodiment of the invention, it can be provided in the retaining device that the first inner ring has a second alignment device for axially aligning the second inner ring relative to the first inner ring. The second alignment device is preferably constructed similarly to the second alignment device of the outer ring. The second alignment device defines the exact relative axial position of the second inner ring relative to the first inner ring in a form-fitting manner in the joined state. This has the advantage that the arrangement of the retaining device on the stator base body and thus the position-accurate retention of the hairpin end region for welding is improved by simple means and in a cost-effective manner.

[0021] Preferably, the outer ring has a wavy structure in a manner directed relative to the first inner ring. Further preferably, the first inner ring has a wavy structure corresponding to the outer ring. Correspondingly, it is preferred that the first inner ring has a wavy structure in a manner relative to the second inner ring, and the second inner ring has a wavy structure corresponding to the first inner ring. Possible additional inner rings are preferably constructed in the same manner. Instead of the wavy structure, the following structure can also be provided, in which adjacent rings of the retaining device (such as the outer ring and the first inner ring, the first inner ring and the second inner ring, etc.) have shape-fitting elements that engage with each other according to a keyway system. By means of the shape-fitting elements (such as in the wavy structure), relative torsion of the rings in the assembled state is prevented by shape fit. For example, the shape-fitting element can be constructed as a capture lug (Fangnase) and a corresponding recess, which has an inclined surface, via which the adjacent rings can be caused to rotate relative alignment when they are joined together in the axial direction. In addition, the position of the recess is particularly easily and reproducibly preset in this way. This has the advantage that the arrangement of the holding device on the stator base body and thus the positionally accurate holding of the hairpin end region for welding is improved by simple means and in a cost-effective manner.

[0022] According to a preferred embodiment of the present invention, the outer ring and / or the first inner ring has a cutting device at the notch. Preferably, the second inner ring and / or the third inner ring and / or the other inner ring has a cutting device. The cutting device is preferably arranged at the notch and is configured to cut the welding burrs extending beyond the notch edge of the notch when the retaining device is demolded. Preferably, the cutting device has a cutting edge or is configured as a cutting edge. For example, the cutting edge can be arranged in the circumferential direction, in the radial direction, in the axial direction, or in a combination of these directions. Preferably, a plurality of cutting edges are configured at each notch, so that the welding burrs can be reliably cut. This has the advantage that the demolding of the retaining device is improved by simple means and in a cost-effective manner, and the risk of damage to the welded connection during demolding is reduced.

[0023] Particularly preferably, the recess has a widening in the axial direction outwards. The widening is preferably designed in such a way that it is directed relative to the stator base body in the assembled state. Thus, when the retaining device is arranged at the stator base body, the hairpin end regions can be pressed into the recess in pairs via the widening. Additionally or alternatively, the widening is preferably designed in such a way that it is directed away from the stator base body in the assembled state. Thus, the retaining device can be caused to slip off at the welding burr via the widening during demolding, and curling at the welding burr can be avoided. For example, the widening can have one or more chamfers. Preferably, the recess has the widening completely. This has the advantage that the arrangement of the hairpin end regions in the recess and the demolding of the retaining device can be improved by simple means and in a cost-effective manner.

[0024] According to the invention, it is preferred that the outer ring and / or the first inner ring have a sliding coating. Preferably, the sliding coating is arranged at least at the contact surface between the outer ring and the first inner ring. It is further preferred that the sliding coating is arranged in a recess in order to improve the slipping off of the retaining device in the hairpin end region. The sliding coating preferably has a particularly high hardness, such as in sliding coatings for plain bearings. The sliding coating is therefore preferably configured according to the sliding coating of a plain bearing. Preferably, the sliding coating is configured as a DLC layer, such as the one from Eifeler under the name As an alternative to the sliding layer, sliding elements such as local structural changes caused by laser processing, welded sliding chips, etc. can also be provided on the outer ring and / or the first inner ring. According to the invention, possible further inner rings can be designed in the same way. This has the advantage that the arrangement of the holding device on the stator base body and the demoulding of the holding device from the stator base body are improved by simple means and in a cost-effective manner.

[0025] According to a second aspect of the invention, this object is achieved by a method for producing a hairpin stator for an electric motor of a motor vehicle. The method comprises:

[0026] - providing a stator base body having twisted hairpins arranged therein,

[0027] - providing a holding device according to at least one of the preceding claims,

[0028] - arranging the outer ring on the stator base body in such a way that the outer ring has a defined radial and axial position relative to the stator base body and surrounds the hairpin end region in the radial direction,

[0029] - arranging the first inner ring on the outer ring in such a way that the hairpin end regions of the first hairpin layer and the hairpin end regions of the second hairpin layer are respectively arranged in a recess formed between the outer ring and the first inner ring,

[0030] - welding the hairpin end regions arranged in the recesses in pairs by means of a welding device,

[0031] - removing the first inner ring from the outer ring, and

[0032] - Remove the outer ring from the stator base.

[0033] First, a stator base body of a hairpin-stator is provided. The stator base body has a stator slot in which a hairpin is arranged. For example, the hairpin can be configured as an I-shaped pin or a U-shaped pin. The hairpin is arranged in the stator slot so that the hairpin end region protrudes from the stator base body in the axial direction. The hairpin is arranged in the stator slot with a plurality of hairpin layers. The outer hairpin layer farthest from the stator longitudinal axis is called the first hairpin layer. The next hairpin layer facing the stator longitudinal axis is the second hairpin layer. The subsequent hairpin layer facing the stator longitudinal axis is the third hairpin layer. The next hairpin layer facing the stator longitudinal axis is the fourth hairpin layer. It is also possible to provide other hairpin layers facing the stator longitudinal axis, such as the fifth hairpin layer and the sixth hairpin layer or the seventh hairpin layer and the eighth hairpin layer in addition.

[0034] The hairpins are twisted. This means that the hairpin end regions of adjacent hairpin layers are delimited differently in the circumferential direction of the stator base body, for example in opposite directions. Furthermore, according to the invention it can be provided that the hairpin end regions widen in the radial direction so that the hairpin end regions of adjacent hairpin layers have a spacing relative to one another in the radial direction which is greater than the spacing of adjacent hairpins in the stator slots.

[0035] Subsequently, a holding device according to the invention is provided. The holding device has at least an outer ring and a first inner ring. Depending on the number of hair clip layers, the holding device may also have one or more inner rings. In the case of a total of two hair clip layers, the outer ring and the first inner ring are sufficient. In the case of a total of four hair clip layers, the holding device has a second inner ring in addition to the outer ring and the first inner ring. In the case of a total of six hair clip layers, the holding device has a third inner ring in addition to the outer ring, the first inner ring, the second inner ring and the third inner ring. In the case of a total of eight hair clip layers, the holding device has a fourth inner ring in addition to the outer ring, the first inner ring, the second inner ring and the third inner ring. In the case of a total of ten hair clip layers, the holding device has a fifth inner ring in addition to the outer ring, the first inner ring, the second inner ring, the third inner ring and the fourth inner ring, and so on. Preferably, the holding device is provided in a disassembled state so that the outer ring is separated from the first inner ring, the possible second inner ring is separated from the first inner ring, and the possible third inner ring is separated from the second inner ring, and so on.

[0036] The outer ring is arranged on the stator base body in such a way that the outer ring has a defined radial and axial position relative to the stator base body and the hairpin end region is surrounded by the outer ring in the radial direction. For this purpose, the outer ring has a first alignment device, which can be designed as a shoulder, or has at least one shoulder, chamfer, end stop or the like. Preferably, the outer ring is arranged on the stator base body in such a way that a further relative movement of the outer ring in the axial direction relative to the stator base body is prevented by the first alignment device in a form-fitting manner. Further preferably, the outer ring is arranged on the stator base body in such a way that a further relative movement of the outer ring in the radial direction relative to the stator base body is prevented by the first alignment device in a form-fitting manner. By means of the outer ring, radial movements of the hairpin end region in the radial direction outwards are limited in a form-fitting manner.

[0037] Subsequently, the first inner ring is arranged at the outer ring. For this purpose, preferably, no contact of the stator matrix by the first inner ring is required. Preferably, the first inner ring is arranged at the outer ring in such a way that further movement of the first inner ring in the axial direction toward the stator matrix is ​​prevented by the second alignment device of the outer ring in a form-fitting manner. In addition, the first inner ring is arranged at the outer ring in such a way that the hairpin end region of the first hairpin layer and the hairpin end region of the second hairpin layer are arranged in a recess formed between the outer ring and the first inner ring. Therefore, the hairpin end region of the first hairpin layer and the hairpin end region of the second hairpin layer are arranged in the recess formed respectively. The recess is constructed in such a way that the two hairpin end regions are arranged side by side for welding, for example in a mutually contacting manner or in the case of a marginal gap. According to the number of hairpin layers, it can be provided according to the invention that the other inner ring is arranged correspondingly to the first inner ring at the corresponding previously arranged inner ring. For example, in the case of four hairpin layers, the second inner ring is arranged at the first inner ring, so that the hairpin end region of the third hairpin layer and the hairpin end region of the fourth hairpin layer are respectively arranged in the recess formed between the second inner ring and the first inner ring. For example, in the case of six hairpin layers, the third inner ring is additionally arranged at the second inner ring, so that the hairpin end region of the fifth hairpin layer and the hairpin end region of the sixth hairpin layer are respectively arranged in the recess formed between the third inner ring and the second inner ring. For example, in the case of eight hairpin layers, the fourth inner ring is additionally arranged at the third inner ring, so that the hairpin end region of the seventh hairpin layer and the hairpin end region of the eighth hairpin layer are respectively arranged in the recess formed between the fourth inner ring and the third inner ring, and so on.

[0038] Subsequently, two hairpin end regions arranged in a corresponding one of the recesses are welded to each other by a welding device (such as a laser welding device, a spot welding device, etc.). In this way, a multi-phase stator winding can be produced by mutually welded hairpins.

[0039] After the welding process, the hairpin end regions are connected to each other in pairs in a form-fitting manner, so that a holding device for holding the hairpin end regions together is no longer required. Preferably, the innermost inner ring is removed first. In the present example with only two hairpin layers, this is the first inner ring. In the case of four hairpin layers, the second inner ring is removed first. In the case of six hairpin layers, the third inner ring is removed first. In the case of eight hairpin layers, the fourth inner ring is removed first, etc. Subsequently, the inner rings that are further inward are removed. Therefore, in the case of four hairpin layers, the first inner ring is removed subsequently. Therefore, in the case of six hairpin layers, the second inner ring is removed subsequently. Therefore, in the case of eight hairpin layers, the third inner ring is removed subsequently, etc.

[0040] Finally, the outer ring is removed from the stator base body. This is preferably done after all inner rings have been removed. According to the invention, it can also be provided that the inner rings are first slightly loosened by movement away from the stator base body in the axial direction and then removed from the stator base body together with the outer rings. The loosening preferably slightly enlarges the recess, thereby improving the movement of the retaining device past the weld.

[0041] The method according to the invention for producing a hairpin stator for an electric motor of a motor vehicle yields all the advantages that have already been described with respect to the holding device according to the first aspect of the invention for holding the hairpin end region of a hairpin of a hairpin stator for an electric motor of a motor vehicle for a welding process. Thus, compared with conventional methods, the method according to the invention has the advantage that the fixing of the hairpin end region for welding is ensured by simple means and in a cost-effective manner. The holding device used when carrying out the method has a particularly strong and simple design and can therefore be easily manufactured. Furthermore, due to the multi-piece design of the holding device, the demoulding of the stator base body after the welding process can be carried out particularly easily by, for example, first removing the first inner ring and then the outer ring in the axial direction from the stator base body. Thus, compared with conventional methods, curling at welding burrs and damage to the welded connection can be avoided better. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The holding device according to the invention and the method according to the invention are explained in more detail below with reference to the accompanying drawings. Schematically:

[0043] Figure 1 A perspective view shows a first state during the execution of a preferred specific embodiment of the method according to the invention,

[0044] Figure 2 A second state during the execution of the preferred embodiment of the method according to the invention is shown in a perspective view,

[0045] Figure 3A third state during the execution of the preferred embodiment of the method according to the invention is shown in a perspective view,

[0046] Figure 4 A fourth state during the execution of the preferred embodiment of the method according to the invention is shown in a perspective view, and

[0047] Figure 5 A fifth state during the execution of this preferred specific embodiment of the method according to the invention is shown in a perspective view.

[0048] exist Figures 1 to 5 In the drawings, elements having the same function and mode of action are respectively provided with the same reference numerals. DETAILED DESCRIPTION

[0049] exist Figure 1 , a first state during the execution of a preferred embodiment of the method according to the invention is schematically shown in a perspective view. In the first state, a stator base body 9 with a hairpin stator 4 is provided, which has a plurality of stator slots 12 extending in the axial direction A of the stator base body 9. The hairpins 3 are arranged in the stator slots 12 in a total of eight hairpin layers.

[0050] The outer hair sandwich layer is called the first hair sandwich layer L1. The hair sandwich layer directly adjacent to the first hair sandwich layer L1 in the radial direction R is called the second hair sandwich layer L2. The hair sandwich layer directly adjacent to the second hair sandwich layer L2 in the radial direction R is called the third hair sandwich layer L3. The hair sandwich layer directly adjacent to the third hair sandwich layer L3 in the radial direction R is called the fourth hair sandwich layer L4. The hair sandwich layer directly adjacent to the fourth hair sandwich layer L4 in the radial direction R is called the fifth hair sandwich layer L5. The hair sandwich layer directly adjacent to the fifth hair sandwich layer L5 in the radial direction R is called the sixth hair sandwich layer L6. The hair sandwich layer directly adjacent to the sixth hair sandwich layer L6 in the radial direction R is called the seventh hair sandwich layer L7. The hair sandwich layer directly adjacent to the seventh hair sandwich layer L7 in the radial direction R is called the eighth hair sandwich layer L8. In other embodiments of the method according to the present invention, more or fewer hair sandwich layers may also be provided.

[0051] The hairpin end regions 2 of the hairpins 3 protrude from the stator base body 9 in the axial direction A and widen in the radial direction R so that the hairpin end regions 2 of the first hairpin layer L1 and the second hairpin layer L2 are arranged in pairs directly side by side and spaced apart from the hairpin end regions 2 of the other hairpin layers. The hairpin end regions 2 of the third hairpin layer L3 and the fourth hairpin layer L4 are arranged in pairs directly side by side and spaced apart from the hairpin end regions 2 of the other hairpin layers. The hairpin end regions 2 of the fifth hairpin layer L5 and the sixth hairpin layer L6 are arranged in pairs directly side by side and spaced apart from the hairpin end regions 2 of the other hairpin layers. The hairpin end regions 2 of the seventh hairpin layer L7 and the eighth hairpin layer L8 are arranged in pairs directly side by side and spaced apart from the hairpin end regions 2 of the other hairpin layers.

[0052] In the first state shown, the outer ring 5 of the retaining device 1 according to the invention is arranged on the stator base body 9 in such a way that the first alignment means 8 designed as a shoulder prevents a further approaching movement of the outer ring 5 in the axial direction A towards the stator base body 9 and a relative movement of the outer ring 5 in the radial direction relative to the stator base body 9 in a form-fitting manner. All hairpin end regions 2 are surrounded by the outer ring 5 in the radial direction R, wherein the free ends of the hairpin end regions 2 protrude beyond the outer ring 5 in the axial direction A. In the region of the hairpin end regions 2, the outer ring 5 has a corrugated structure facing the hairpins 3. In this view, the second alignment means 10 designed as a shoulder on the outer ring 5 and facing the hairpins 3 can be seen.

[0053] Figure 2 The second state during the execution of the preferred embodiment of the method according to the invention is schematically shown in a perspective view. In the second state, the first inner ring 6 is arranged on the outer ring 5 in such a way that the first inner ring 6 rests on the second alignment means 10 of the outer ring 5 and is thus prevented from further movement of the first inner ring 6 in the direction of the stator base body 9 by the second alignment means 10 of the outer ring 5 in a form-fitting manner. The first inner ring 6 has a corrugated structure corresponding to the outer ring 5. A plurality of recesses 7 are formed between the outer ring 5 and the first inner ring 6, in which the hairpin end regions 2 of the first hairpin layer L1 and the hairpin end regions 2 of the second hairpin layer L2 are respectively arranged, wherein the hairpin end regions 2 are held together in the recesses 7. In this view, the second alignment means 10, which is formed as a shoulder on the first inner ring 6 and faces away from the outer ring 5, can be seen.

[0054] exist Figure 3, a third state during the execution of the preferred embodiment of the method according to the invention is schematically depicted in a perspective view. In the third state, the second inner ring 11 is additionally arranged on the first inner ring 6 in such a way that the second inner ring 11 rests on the second alignment device 10 of the first inner ring 6 and is thus prevented from further movement of the second inner ring 11 in the direction of the stator base body 9 by the second alignment device 10 of the first inner ring 6 in a form-fitting manner. The second inner ring 11 has a wave-shaped structure corresponding to the first inner ring 6. A plurality of recesses 7 are formed between the first inner ring 6 and the second inner ring 11, in which the hairpin end regions 2 of the third hairpin layer L3 and the hairpin end regions 2 of the fourth hairpin layer L4 are respectively arranged, wherein the hairpin end regions 2 are held together in the recesses 7. In this view, the second alignment device 10, which is formed as a shoulder on the second inner ring 11 and faces away from the first inner ring 6, can be seen.

[0055] Figure 4 The fourth state during the execution of the preferred embodiment of the method according to the invention is schematically shown in a perspective view. In the fourth state, the third inner ring 13 is additionally arranged on the second inner ring 11 in such a way that the third inner ring 13 rests on the second alignment device 10 of the second inner ring 11 and is thus prevented from further movement of the third inner ring 13 in the direction of the stator base body 9 by the second alignment device 10 of the second inner ring 11 in a form-fitting manner. The third inner ring 13 has a wave-shaped structure corresponding to the second inner ring 11. A plurality of recesses 7 are formed between the second inner ring 11 and the third inner ring 13, in which the hairpin end regions 2 of the fifth hairpin layer L5 and the hairpin end regions 2 of the sixth hairpin layer L6 are respectively arranged, wherein the hairpin end regions 2 are held together in the recesses 7. In this view, the second alignment device 10, which is formed as a shoulder on the third inner ring 13 and faces away from the second inner ring 11, can be seen.

[0056] exist Figure 5 , a fifth state during the execution of the preferred embodiment of the method according to the invention is schematically shown in a perspective view. In the fifth state, the fourth inner ring 14 is additionally arranged at the third inner ring 13 in such a way that the fourth inner ring 14 rests on the second alignment device 10 of the third inner ring 13 and is thus prevented from further movement of the fourth inner ring 14 in the direction of the stator base body 9 by the second alignment device 10 of the third inner ring 13 in a form-fitting manner. The fourth inner ring 14 has a wave-shaped structure corresponding to the third inner ring 13. A plurality of recesses 7 are formed between the third inner ring 13 and the fourth inner ring 14, in which the hairpin end regions 2 of the seventh hairpin layer L7 and the hairpin end regions 2 of the eighth hairpin layer L8 are arranged respectively, wherein the hairpin end regions 2 are held together in the recesses 7.

[0057] exist Figure 5In the fifth state shown in FIG, the hairpin end regions 2 remain for a subsequent welding process, in which the hairpin end regions 2 arranged in pairs in the recesses 7 are welded to each other. After the welding process, the holding device 1 is removed from the stator base body 9 again. According to the invention, it is preferred here that the fourth inner ring 14 is first removed from the stator base body 9, then the third inner ring 13, then the second inner ring 12, then the first inner ring 6, and finally the outer ring 5 are removed from the stator base body 9.

[0058] Reference numerals list

[0059] 1 Holding device

[0060] 2 Hairpin end region

[0061] 3 Hairpins

[0062] 4 Hairpin-Stator

[0063] 5 Outer Ring

[0064] 6 First Inner Ring

[0065] 7 Notch

[0066] 8. First alignment device

[0067] 9 Stator base

[0068] 10 Second alignment device

[0069] 11 Second Inner Ring

[0070] 12 stator slots

[0071] 13 The third inner ring

[0072] 14 Fourth Inner Ring

[0073] A Axial direction

[0074] L1 First hair layer

[0075] L2 second hair sandwich layer

[0076] L3 Third hair layer

[0077] L4 Fourth hair layer

[0078] L5 Fifth hair layer

[0079] L6 Sixth hair layer

[0080] L7 Seventh hair layer

[0081] L8 Eighth hair layer

[0082] R Radial direction

Claims

1. A holding device (1) for holding a hairpin end region (2) of a hairpin (3) of a hairpin stator (4) of an electric motor of a motor vehicle for a welding process, wherein: The hairpin (3) is arranged from outside to inside in a radial direction (R) with a first hairpin layer (L1), a second hairpin layer (L2), a third hairpin layer (L3) and a fourth hairpin layer (L4), and the retaining device comprises an outer ring (5) for circumferentially surrounding the hairpin end region (2) and at least one first inner ring (6) configured separately from the outer ring (5) and arranged in the outer ring (5) so that the hairpin end regions (2) of the first hairpin layer (L1) and the second hairpin layer (L2) are arranged on the outer ring (5) and The invention relates to a hairpin stator (4) and a hairpin-stator (5), wherein the outer ring (5) and the first inner ring (6) are configured to form recesses (7) for accommodating the hairpin end regions (2) of the first hairpin layer (L1) and the second hairpin layer (L2) in pairs in an assembled state, wherein the outer ring (5) has a first alignment device (8) for alignment relative to a stator base body (9) of the hairpin-stator (4), and wherein the outer ring (5) and the first inner ring (6) are configured to be arranged continuously on the stator base body (9).

2. The holding device (1) according to claim 1, It is characterized in that The first alignment device (8) is configured to align the outer ring (5) relative to the stator base body (9) in an axial direction (A) and a radial direction (R).

3. The holding device (1) according to claim 1 or 2, It is characterized in that The outer ring (5) has second alignment means (10) for axially aligning the first inner ring (6) relative to the outer ring (5).

4. Holding device (1) according to at least one of the preceding claims, It is characterized in that The retaining device (1) has a second inner ring (11) for being arranged in the first inner ring (6) in such a way that the hairpin end regions (2) of the third hairpin layer (L3) and the fourth hairpin layer (L4) are arranged between the first inner ring (6) and the second inner ring (11), wherein the first inner ring (6) and the second inner ring (11) are configured to form recesses (7) for accommodating the hairpin end regions (2) of the third hairpin layer (L3) and the fourth hairpin layer (L4) in pairs in an assembled state.

5. The holding device (1) according to claim 4, It is characterized in that The first inner ring (6) has second alignment means (10) for axially aligning the second inner ring (11) relative to the first inner ring (6).

6. Holding device (1) according to at least one of the preceding claims, It is characterized in that The outer ring (5) has a wave-shaped structure in a manner directed relative to the first inner ring (6), and the first inner ring (6) has a wave-shaped structure corresponding to the outer ring (5).

7. Holding device (1) according to at least one of the preceding claims, It is characterized in that The outer ring (5) and / or the first inner ring (6) has cutting means at the recess (7).

8. Holding device (1) according to at least one of the preceding claims, It is characterized in that The recess (7) has a widening outwards in the axial direction (A).

9. Holding device (1) according to at least one of the preceding claims, It is characterized in that The outer ring (5) and / or the first inner ring (6) have a sliding coating.

10. A method for producing a hairpin stator (4) for an electric motor of a motor vehicle, comprising: - providing a stator base body (9) having twisted hairpins (3) arranged therein, - providing a holding device (1) according to at least one of the preceding claims, - the outer ring (5) is arranged on the stator base body (9) in such a way that the outer ring (5) has a defined radial and axial position relative to the stator base body (9) and surrounds the hairpin end region (2) in the radial direction (R), - arranging the first inner ring (6) at the outer ring (5) in such a way that the hairpin end region (2) of the first hairpin layer (L1) and the hairpin end region (2) of the second hairpin layer (L2) are respectively arranged in a recess (7) formed between the outer ring (5) and the first inner ring (6), - welding the hairpin end regions (2) arranged in the recesses (7) in pairs by means of a welding device, - removing the first inner ring (6) from the outer ring (5), and - Removing the outer ring (5) from the stator base body (9).

Images