Method for producing stator, electric machine and motor vehicle

Abstract

The invention relates to a method for producing a stator (1) for driving an electric machine (2) of a motor vehicle (3). According to the method, a stator base body (5) having a plurality of stator slots (6) is provided. The winding bars (7) are arranged in the stator slots (6). The first winding heads (10) are arranged on the stator base body (5) in such a way that the free winding head ends (11) of the first winding heads (10) are each joined to the free rod ends (8) of the winding rods (7). Finally, the free winding head ends (11) are connected to the respective associated free rod ends (8). The invention further relates to an electric machine (2) for driving a motor vehicle (3) and to a motor vehicle (3) having an electric drive system (15).

Description

Technical Field

[0001] This invention relates to a method for manufacturing a stator for an electric motor used to drive a motor vehicle. Furthermore, this invention relates to an electric motor for driving a motor vehicle and a motor vehicle having an electric drive system. Background Technology

[0002] Electric drive systems for motor vehicles are known, which have motors to drive the vehicles. To achieve high power density, the motors typically have stator windings formed by winding bars. The winding bars are arranged radially in multiple slots within the stator slots of the stator matrix. These winding bars are sometimes called "hairpins" because they have a hairpin-like construction.

[0003] In the winding bar, a distinction is essentially made between U-shaped hairpins or U-shaped leads and I-shaped hairpins or I-shaped leads. A U-shaped lead has a curved region with a U-shaped structure from which two wire legs, each with a free leg end, extend. To achieve the stator winding, the free leg ends are first widened radially and then twisted circumferentially. In this way, the free leg ends of the different hairpins converge in pairs.

[0004] Next, the converging legs are mechanically and electrically connected to each other, for example, by welding, crimping, brazing, etc. Thus, the bent region at the first base end forms the first winding head, and the leg end at the second base end opposite the first base end forms the second winding head. The I-shaped pins substantially correspond to the legs of the U-shaped pins, thus requiring widening, twisting, and joining at both base ends to manufacture the stator winding.

[0005] Various hairpin-tech stators are known from documents DE 10 239 730 A1 and DE 10 2023 101 033 A1. Document DE 10 2022 113 127 A1 discloses a stator winding produced by I-shaped leads. Instead of widening and twisting, the free-side legs of the I-shaped leads are mechanically and electrically interconnected via multiple individual bridging elements. For this purpose, the I-shaped leads are first arranged parallel to each other on a plane, and then combined with the bridging elements to form a stabmatte. Alternatively, the stabmatte can also be produced by modifying a continuous wire. For each stator phase, the stabmatte is then inserted into a stator slot in the stator matrix.

[0006] Known hairpin stators and methods for manufacturing stator windings have the following drawbacks: for example, the manufacturing of the winding head can sometimes be very complex and time-consuming due to the individual arrangement and welding of bridging elements to the free leg ends. Furthermore, a relatively large structural space must be maintained for laser welding of the free leg ends, resulting in a relatively large winding head in the axial and / or radial directions. Summary of the Invention

[0007] Therefore, the object of the present invention is to eliminate or at least partially eliminate the aforementioned disadvantages in stator windings constructed from hairpins. In particular, the object of the present invention is to create a method for manufacturing a stator for an electric motor for driving a motor vehicle, an electric motor for driving a motor vehicle, and a motor vehicle having an electric drive system, which simplifies the manufacturing of stator windings and / or has winding heads with particularly small dimensions in a simple and cost-effective manner.

[0008] The aforementioned task is solved by the subject matter of the invention. Therefore, the task is solved by the method according to the invention for manufacturing a stator for an electric motor for driving a motor vehicle, the invention for driving a motor vehicle, and the invention for a motor vehicle having an electric drive system. Further features and details of the invention are derived from the description and drawings. The features and details described in conjunction with the method according to the invention for manufacturing a stator for an electric motor for driving a motor vehicle naturally also apply to the electric motor according to the invention and the motor vehicle according to the invention, and vice versa, so that the disclosure of each aspect of the invention is always mutually referential or can be mutually referenced.

[0009] According to a first aspect of the invention, this task is solved by a method for manufacturing a stator for an electric motor used to drive a motor vehicle. The method comprises: - Provides a stator matrix with multiple stator slots extending along the longitudinal axis of the matrix; - The winding rods, each having at least one free end, are arranged in the stator slots such that the free ends of the winding rods are located at the first base end side of the stator base. - A first winding head having multiple free winding head ends is arranged at the end side of the first base such that one of the free rod ends is associated with one of the free winding head ends; and - In the case of constructing a connection section, connect the free winding head end to the respective associated free rod end.

[0010] First, a stator substrate is provided. The stator substrate is preferably constructed as a stator lamination assembly consisting of a plurality of stator lamination disks coaxial with the longitudinal axis of the substrate. The stator lamination disks are preferably made of electrical steel sheet and more preferably have an electrically insulating coating, such as paint. The stator substrate extends along the longitudinal axis of the stator. Preferably, the stator substrate extends fully around the longitudinal axis of the stator, particularly preferably all over it. A plurality of stator slots are constructed in the stator substrate, which are preferably evenly distributed on the stator substrate in the circumferential direction. The stator slots are preferably constructed to be open in the radial direction toward the longitudinal axis of the substrate. In the radial direction, the stator slots have a slot depth. In the circumferential direction, the stator slots have a slot width. In the axial direction, the stator slots have a slot length. The stator slots are preferably constructed parallel to the longitudinal axis of the substrate. Preferably, the stator slots are open at both ends of the stator substrate.

[0011] Next, the winding rods are arranged in the stator slots. Preferably, the winding rods have a width corresponding to or only slightly smaller than the slot width. In the radial direction, the winding rods are arranged side by side in a plurality of slots. The winding rods are arranged in the stator slots such that the free ends of the winding rods are positioned at the first base end side. This means that the free ends can, for example, be arranged adjacent to the free end side within the stator slot. In other words, the winding rods can terminate within the stator slots. Here, the winding rods can, for example, end flush with the stator base, or have already terminated within the stator slots. Preferably, the winding rods are arranged in the stator slots such that the free ends protrude from the stator slots at the first base end side.

[0012] Now, the first winding head is preferably moved toward the first base end side during axial movement. Here, the first winding head is preferably oriented coaxially with the longitudinal axis of the base. The free winding head ends of the first winding head are pointed in the direction of the free rod ends such that each free winding head end is associated with a free rod end. The first winding head is preferably moved toward the stator base such that the free winding head ends contact the free rod ends, preferably in such a way that further axial movement of the first winding head toward the stator base is preferably shape-fitted and restricted. The first winding head is preferably manufactured as a winding head with a complete structure having multiple torsional and / or bent winding head rods. The winding head rods preferably correspond to the winding rods in terms of material and / or cross-section. Preferably, the first winding head is moved toward the stator base such that the free winding head ends simultaneously contact the free rod ends.

[0013] Finally, the free winding head is connected to the respective associated free rod ends. Here, a connection section appears. The connection is made such that the free winding head is electrically connected to the respective associated free rod ends, thereby forming a stator winding or at least one side of a stator winding. Particularly preferably, the connection is made such that the free winding head is mechanically connected to the respective associated free rod ends, thereby preventing the first winding head from detaching from the free rod ends. Alternatively or additionally, the first winding head can be secured to the stator base, for example, by establishing a clamping connection, snap-fit ​​connection, welding connection, brazing connection, etc., between the first winding head and the stator base.

[0014] The winding bar can be constructed, for example, as an I-shaped pin. A winding bar constructed as an I-shaped pin has two opposing free ends. Therefore, the winding bar constructed as an I-shaped pin is arranged in the stator slot such that the other free end of the winding bar is positioned at a second base end opposite to the first base end. Furthermore, a second winding head having multiple free winding head ends is arranged at the second base end such that one of the free ends is associated with one of the free winding head ends. Finally, in this case, if a connection section is constructed at the second winding head end, the free winding head end is also connected to the respective associated free end.

[0015] The method for manufacturing a stator for an electric motor for driving a motor vehicle according to the present invention has advantages over conventional methods in that it provides a winding head with a particularly small size in a simple and cost-effective manner. By providing a separately constructed first winding head, the structural space of the stator can be advantageously reduced. Furthermore, since the first winding head can be pre-assembled and temporarily stored, and the connection between the first winding head and the free rod end can be easily and reliably performed during final assembly, the stator can be easily manufactured using the method according to the present invention.

[0016] According to a preferred improvement of the invention, in a method for manufacturing a stator for a motor for driving a motor vehicle, the first winding head can be arranged at the end of the first base such that the free rod end and the free winding head end form an overlapping region, wherein a connecting section is generated in this overlapping region. Within the scope of the invention, the overlapping region is understood as a region extending in the axial direction, in which the free winding head end and the associated free rod end are arranged. Thus, in the radial and / or circumferential directions, the free winding head end and the free rod end are partially arranged in the overlapping region. Therefore, the overlapping region is distinct from a butt contact, in which the winding head rod end side, constructed similarly to the hairpin end side extending longitudinally at 90°, contacts the hairpin end side, and where no overlap occurs in the axial direction. This has the advantage that a particularly large contact surface can be established between the free rod end and the free winding head end by simple means and in a cost-effective manner. Therefore, the electrical and mechanical connection between the first winding head and the free rod end can be improved.

[0017] According to a preferred embodiment of the invention, the winding bar is arranged in a stator slot having a reduced first cross-section at the free end. The reduced first cross-section can be configured, for example, as a gradient or step-recession towards the end of the winding bar. The gradient-recession can, for example, have a triangular or trapezoidal cross-section. Therefore, the recess preferably extends axially along a section of the winding bar. Alternatively or additionally, it is preferred that the first winding head is arranged at the end of the first base, wherein the free winding head end has a reduced second cross-section. The reduced second cross-section can be configured, for example, as a gradient or step-recession towards the free winding head end. Therefore, the recess preferably extends axially along a section of the winding head. The reduced first and reduced second cross-sections are preferably geometrically coordinated, for example, by the same pitch, matching offsets, for example, according to tenon joints, etc. This has the advantage that a particularly large contact surface can be established between the free end and the free winding head end by simple means and in a cost-effective manner. Therefore, the electrical and mechanical connections between the first winding head and the free rod end can be improved.

[0018] More preferably, the winding rod and the first winding head are interconnected by a tenon-and-groove connection. For this purpose, for example, the free rod end may have a tenon, and the free winding head end may have a groove corresponding to the tenon. Alternatively or additionally, the free winding head end may have a tenon, and the free rod end may have a groove corresponding to the tenon. The tenon-and-groove connection forms an overlapping area extending axially between the free rod end and the free winding head end. This has the advantage that a particularly large contact surface can be established between the free rod end and the free winding head end in a simple and cost-effective manner. Therefore, the electrical and mechanical connection between the first winding head and the free rod end can be improved.

[0019] In a particularly preferred embodiment of the invention, in a method for manufacturing a stator for a motor for driving a motor vehicle, the connection section can be manufactured by brazing or welding. Particularly preferred is the manufacturing of the connection section by brazing. For this purpose, before arranging the first winding head at the end of the first base, brazing material is arranged at the free rod end and / or the free winding head end, for example as a brazing plate, as a coating (e.g., by immersion), etc. The brazing material is preferably constructed as a hard solder. After arrangement, the winding rod is preferably energized such that the winding rod heats up and thereby melts or thaws the brazing material. The current and / or voltage used for this purpose is preferably significantly higher than the operating current or operating voltage set for operating the stator, thereby preventing the brazing material from melting during stator operation. After energization ends, the brazing material cools and hardens again. Preferably, the first winding head is pressed axially against the stator base during the melting and / or during the solidification of the brazing material. Possible welding is preferably performed as spot welding. This has the advantage that the electrical and mechanical connection between the first winding head and the free bar end can be improved in a simple and cost-effective manner.

[0020] Preferably, the connection section is manufactured by pressing. Pressing can be performed alternatively to or in addition to brazing or welding. During pressing, the material of the free rod end and / or the free winding head end is modified such that the free rod end is held at the free winding head end, for example, by means of a press-fit connection. Alternatively or additionally, pressing can also be performed using additional material previously arranged at the free rod end and / or the free winding head end. Pressing is preferably performed by a pressing tool that circumferentially transmits a force acting in a radial direction toward the longitudinal axis of the base to the overlapping area. Preferably, the mating supports of the pressing tool are arranged in the stator base to provide passive or active reaction force in a radial direction away from the longitudinal axis of the base. Alternatively or additionally, due to the geometry of the stator base, its construction, or clamping devices arranged in the stator base, pressing can be performed when the first winding head is pushed onto the free rod end. This has the advantage that the electrical and mechanical connection between the first winding head and the free rod end can be improved by simple means and in a cost-effective manner.

[0021] According to a preferred embodiment of the invention, pressing is performed by pressing in conjunction with a water jacket of the stator cooling device. The stator cooling device may, for example, have a water jacket that radially surrounds the overlapping region from the outside. When the first winding head is positioned at the first base end, the stator cooling device restricts the radial outward extension of the overlapping region, thereby generating a clamping force. This has the advantage that the electrical and mechanical connection between the first winding head and the free rod end can be improved in a simple and cost-effective manner.

[0022] Particularly preferably, the winding rods arranged in the stator slots are constructed with U-shaped leads. Therefore, a second winding head is already formed on the second base end of the stator base opposite to the first base end, thus requiring only the first winding head to be arranged at the winding rod to manufacture the complete stator winding. This has the advantage of further simplifying stator manufacturing in a simple and cost-effective manner.

[0023] According to a second aspect of the invention, this task is accomplished by an electric motor for driving a motor vehicle. The motor has a rotor and a stator extending along the longitudinal axis of a base, the stator having a stator base extending along the longitudinal axis of the base, in which a plurality of stator slots are formed. Stator windings are arranged in the stator slots and at the base end of the stator base. According to the invention, the stator is manufactured by the method according to the invention. Thus, the stator winding is formed on one hand by a winding bar and on the other hand by a first winding head. In a winding bar configured with U-shaped leads, the stator winding is formed by the winding bar and the first winding head. In a winding bar configured with I-shaped leads, the stator winding is formed by the winding bar, the first winding head, and the second winding head.

[0024] In the motor for driving a motor vehicle according to the invention, all the advantages already described with respect to the method of manufacturing the stator of the motor for driving a motor vehicle according to the first aspect of the invention are realized. Therefore, the motor according to the invention has the advantage over conventional motors that it provides a winding head with a particularly small size by simple means and in a cost-effective manner. By utilizing a separately constructed first winding head to form the stator winding, the structural space of the stator is advantageously reduced, resulting in a smaller size and lighter weight for the motor according to the invention compared to conventional motors. Furthermore, since the first winding head can be pre-assembled and temporarily stored, and the connection between the first winding head and the free bar end can be easily and reliably performed during final assembly, the stator of this motor can be manufactured particularly easily.

[0025] According to a third aspect of the invention, this task is accomplished by a motor vehicle having an electric drive system. The electric drive system has a traction battery for storing and supplying electrical energy. According to the invention, the electric drive system has a motor according to the invention for driving the motor vehicle.

[0026] In the motor vehicle according to the invention, all the advantages described with respect to the method for manufacturing the stator of an electric motor for driving a motor vehicle according to the first aspect of the invention and the electric motor for driving a motor vehicle according to the second aspect of the invention are obtained. Therefore, the motor vehicle according to the invention has the advantage over conventional motor vehicles that it provides a winding head with a particularly small size by simple means and in a cost-effective manner. By utilizing a separately constructed first winding head to form the stator winding, the structural space of the stator is advantageously reduced, resulting in a motor according to the invention having a smaller size and lighter weight compared to conventional motors. Furthermore, since the first winding head can be pre-assembled and temporarily stored, and the connection between the first winding head and the free bar end can be easily and reliably performed during final assembly, the stator of this motor can be manufactured particularly easily. Attached Figure Description

[0027] The electric motor according to the invention, the motor vehicle according to the invention, and the method according to the invention are explained in more detail below with reference to the accompanying drawings. The drawings illustrate, respectively: Figure 1 The stator according to the prior art is shown in a side view. Figure 2 The first state during the execution of a preferred first embodiment of the method according to the invention is shown in perspective detail. Figure 3 The second state during the execution of a preferred first embodiment of the method according to the invention is shown in a side cross-sectional view. Figure 4 The third state during the execution of a preferred first embodiment of the method according to the invention is shown in a side cross-sectional view. Figure 5 Shown in side detail view Figure 4 The third state in Figure 6 The third state during the execution of the preferred second embodiment of the method according to the invention is shown in a side cross-sectional view. Figure 7 An exploded perspective view shows a motor according to a preferred embodiment of the invention. Figure 8 A preferred embodiment of the motor vehicle according to the invention is shown in a side view, and Figure 9 A preferred embodiment of the method according to the invention is illustrated in a flowchart.

[0028] exist Figures 1 to 9 In this context, elements with the same function and operating mode are given the same reference numerals. Detailed Implementation

[0029] exist Figure 1 The stator 1 according to the prior art is schematically depicted in a side view. The stator 1 has a stator base 5 extending along the longitudinal axis 4 of the base. Stator windings composed of winding rods 7 are arranged at the stator base 5. The winding rods 7 are constructed as U-shaped leads and have bending regions at the second base end side 18 of the stator base 5, through which a second winding head 19 is formed. At the first base end side 9 opposite to the first base end side 18, the winding rods 7 have free rod ends 8, which converge in pairs and weld together to form a first winding head 10. A disadvantage of this stator 1 is that the first winding head 10 has a particularly large extension in the axial direction.

[0030] Figure 2 A first state during the execution of a preferred first embodiment of the method according to the invention is shown schematically in a detailed perspective view. In the first state, a stator base 5 is provided, wherein a plurality of stator slots 6 are configured in a circumferential direction. The winding rods 7 are arranged in the stator slots 6 such that the free rod ends 9 protrude from the stator slots 6 at a first base end 9 of the stator base 5.

[0031] exist Figure 3 The diagram schematically illustrates a second state during the execution of a preferred first embodiment of the method according to the invention in a side cross-sectional view. In this second state, the first winding head 10 is arranged coaxially with the stator base 5 such that each free winding head end 11 of the winding head 10 is associated with a free rod end 8. In this second state, the first winding head 10 is movable axially toward the stator base 5 to engage the free winding head ends 11 with the free rod ends 8. Furthermore, a clamping device 20 is arranged at the first winding head 10. The clamping device 20 is configured to press against the first base end side 9, thereby applying a radially acting clamping force to the free winding head ends 11 during engagement with the first winding head 10. In this view, it can be clearly seen that the winding rod 7 is constructed as a U-shaped pin, wherein a curved region at the second base end side 18 forms a second winding head 19.

[0032] Figure 4 The third state is schematically shown in a side cross-sectional view during the execution of a preferred first embodiment of the method according to the invention. Figure 5 The diagram is schematically shown in a side detail view. Figure 4The third state is described above. In this third state, the first winding head 10 is arranged at the stator base 5 such that the free winding head end 11 engages with the free rod end 8, forming a common overlapping area 12 in the axial direction. Furthermore, the clamping device 20 presses against the first base end side 9 such that the clamping device 20 applies a clamping force radially to the overlapping area 12, thereby clamping the free winding head end 11 and the free rod end 8.

[0033] Figure 6 The third state during the execution of the preferred second embodiment of the method according to the invention is schematically shown in a side cross-sectional view. Instead of the clamping device 20, a water jacket 13 of the cooling device of the stator 1 is arranged around the overlapping region 12. The clamping force for clamping the free winding head end 11 to the free rod end 8 is applied radially toward the longitudinal axis 4 of the base via the water jacket 13 onto the overlapping region 12.

[0034] exist Figure 7 The electric motor 2 according to a preferred embodiment of the invention is schematically depicted in an exploded perspective view. The electric motor 2 has a stator 1 according to the invention and a rotor 14 arranged coaxially with the stator 1. A first winding head 10 connected to the winding bar 7 of the stator 1 can be seen in this view. The stator 1 is surrounded by a three-piece housing 17. Power electronics 21, arranged in a separately constructed housing, are located on the upper side of the housing 17.

[0035] Figure 8 A preferred embodiment of the motor vehicle 3 according to the invention is schematically shown in a side view. The motor vehicle 3 has an electric drive system 15, which includes a traction battery 16 and a motor 2 according to the invention for driving the motor vehicle 3.

[0036] exist Figure 9 A preferred embodiment of the method according to the invention is schematically presented in a flowchart. In the first method action 100, a stator base 5 is provided. In the second method action 200, a winding rod 7 is arranged in the stator slot 6 of the stator base 5 such that the three ends 8 of the winding rod 7 protrude from the stator slot 6 at the first base end side 9 of the stator base 5.

[0037] In the third method operation 300, a first winding head 10 having multiple free winding head ends 11 is arranged at the first base end side 9 such that one of the free winding head ends 11 is associated with one of the free rod ends 8. In the fourth method operation 400, when constructing a connection section, the free winding head ends 11 are connected to the respective associated free rod ends 8.

[0038] List of reference numerals 1. Stator 2 motors 3 Motor vehicles 4. Longitudinal axis of the matrix 5. Stator substrate 6 stator slots 7 Winding rods 8 Free rod end 9 First matrix end side 10 First winding head 11 Free winding head end 12 Overlapping regions 13 Water Jackets 14 Rotors 15 Electric drive system 16 Traction batteries 17 Machine casing 18 Second matrix end side 19 Second winding head 20 Clamping device 21 Power Electronic Devices 100 First Method Action 200 Second Method Action 300 Third Method Actions 400 Fourth method action.

Claims

1. A method for producing a stator (1) of an electric machine (2) for driving a motor vehicle (3), having: - providing a stator base body (5) having a plurality of stator slots (6) extending along a base body longitudinal axis (4); - arranging winding bars (7) each having at least one free bar end (8) in the stator slots (6) such that the free bar ends (8) of the winding bars (7) are arranged at a first base body end side (9) of the stator base body (5); - arranging a first winding head (10) having a plurality of free winding head ends (11) at the first base body end side (9) such that one of the free bar ends (8) is associated with one of the free winding head ends (11), respectively; and - connecting the free winding head ends (11) with the free bar ends (8) associated, respectively, in the case of a construction connection section.

2. The method as claimed in claim 1, characterized in that the first winding head (10) is arranged at the first base body end side (9) such that the free bar ends (8) form an overlap region (12) with the free winding head ends (11), wherein the connection section is produced in the overlap region (12).

3. The method as claimed in claim 1 or 2, characterized in that winding bars (7) having a reduced first bar cross section at the free bar ends (8) are arranged in the stator slots (6).

4. The method as claimed in claim 3, characterized in that the winding bars (7) and the first winding head (10) are connected to one another according to a tongue-and-groove connection.

5. The method as claimed in any of the preceding claims, characterized in that the connection section is produced by brazing or welding.

6. The method as claimed in any of the preceding claims, characterized in that the connection section is produced by pressing.

7. The method as claimed in claim 6, characterized in that the pressing is carried out by pressing in in cooperation with a water jacket (13) of a stator cooling device of the stator (1).

8. The method as claimed in any of the preceding claims, characterized in that the winding bars (7) arranged in the stator slots (6) are configured as U-shaped pins.

9. A motor vehicle (3) having an electric drive system (15) with a traction battery (16) for storing and providing electrical energy, characterized in that the electric drive system (15) has an electric machine (2) as claimed in claim 9 for driving the motor vehicle (3).

10. A motor vehicle (3) having an electric drive system (15) with a traction battery (16) for storing and providing electrical energy, characterized in that the electric drive system (15) has an electric machine (2) as claimed in claim 9 for driving the motor vehicle (3). ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 9. An electric machine (2) for driving a motor vehicle (3), having a rotor (14) and a stator (1) which extend along a base body longitudinal axis (4), the stator having a stator base body (5) which extends along the base body longitudinal axis (4), a plurality of stator slots (6) being configured in the stator base body, wherein ​ ​ ​ ​ ​ ​

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