Stator of an electric machine, method for manufacturing such a stator and electric machine

Abstract

The invention relates to a stator of an electric machine, having a stator lamination stack composed of lamination blanks (16a) having notches (18), wherein the notches (18) are closed radially inward by bridges (19) as viewed in a cross section extending in the radial direction of the stator (14), and stator windings (17) accommodated in the notches (18) of the stator lamination stack (16), wherein the bridges (19) radially inwardly closing the respective notch (18) are plastically deformed in such a way that mechanical stresses are introduced into the bridges. The invention also relates to a method for producing such a stator and an electric machine.

Description

Technical Field

[0001] The present invention relates to a stator of an electric motor, an electric motor having a stator, and a method for manufacturing a stator. Background Technology

[0002] The principle of electric motor construction is known from practice. Therefore, an electric motor has a stator, which comprises a housing, stator laminations, and stator windings with winding heads. This stator is also referred to as the stationary component. In addition, the electric machine has a rotor, which has a rotor shaft and rotor laminations. This rotor is also referred to as the moving part.

[0003] The stator laminations of an electric motor are composed of multiple lamination blanks, each blank having slots for accommodating the stator windings.

[0004] These slots are typically open recesses that radially and internally abut the rotor of the electric motor. Therefore, US 2015 / 0 001 984 A1, US 2017 / 0 294 812 A1, US 2018 / 0 233 969 A1, US 2003 / 0 030 350 A1, US 2015 / 0 008 785 A1, DE 36 08 472 A1, DE 10 2017 211 452 A1, and JP 2010-239 721 A disclose stators of electric motors having stator laminations and stator windings, wherein the stator windings are positioned in recessed, radially open slots within the stator laminations.

[0005] US 2003 / 0 201 687 A1 discloses a stator of an electric machine having stator laminations and stator windings, the stator windings being housed in slots in the stator laminations. The slots are designed such that, viewed in a cross-section extending radially in the stator, the slots are closed radially inward by bridging portions.

[0006] During the operation of electric machines, so-called bearing currents may form, which refer to the current flowing through the bearing. This can cause changes in the bearing material, potentially leading to bearing failure. There is a need to reduce the risk of bearing currents, more specifically when the power density of electric machines remains consistently high, as previously mentioned. Summary of the Invention

[0007] The object of the present invention is to provide a novel stator for an electric motor, an electric motor having such a stator, and a method for manufacturing such a stator.

[0008] This objective is achieved by the stator of the electric machine according to the invention.

[0009] The stator has a stator lamination assembly composed of lamination blanks with slots, wherein, viewed in a cross-section extending radially in the stator, these slots are closed radially inward by bridging portions. Furthermore, the stator has stator windings housed within the slots of the stator lamination assembly. The bridging portions that close the corresponding slots radially inward are plastically deformed such that mechanical stress is introduced into these bridging portions.

[0010] In the stator according to the invention, the risk of bearing current is reduced because the slots accommodating the stator windings in the stator laminations are closed radially inward by bridging portions. By plastically deforming the bridging portions and introducing mechanical stress into these bridging portions, the magnetic properties of the stator laminations in the bridging region are weakened, thereby effectively resisting the formation of bearing current even at high power densities in electric machines.

[0011] Preferably, mechanical stress is introduced into the bridging portion that radially closes the corresponding slot, and this mechanical stress is greater than the yield strength of the bridging portion material. This improvement is particularly advantageous in resisting bearing currents at higher power densities in electric machines.

[0012] Preferably, the free space between the bridging portions of plastically deformed adjacent laminated blanks along the axial direction is filled with an insulating backlack or adhesive connecting the laminated blanks. This improvement is also preferably effective against bearing currents at higher power densities in electric machines.

[0013] Preferably, the bridging portion is plastically deformed along the axial direction of the stator lamination assembly, thereby reducing the thickness of the lamination blank in the corresponding bridging portion region at least in sections. This also effectively resists the formation of bearing currents while maintaining a high power density in the electric machine.

[0014] The present invention also provides an electric motor and a method for manufacturing a stator.

[0015] Preferred improvements to the present invention are derived from preferred embodiments and the following description. Attached Figure Description

[0016] Embodiments of the present invention will be described in detail with reference to the accompanying drawings, but are not limited thereto. In the drawings:

[0017] Figure 1 A cross-section through the electric motor is shown;

[0018] Figure 2 A perspective view of the stator of an electric machine is shown;

[0019] Figure 3 A simplified front view of the stator of an electric machine is shown; and

[0020] Figure 4 It shows Figure 3 Details. Detailed Implementation

[0021] Figure 1 The basic structure of the electric machine 10 is shown in a highly schematic cross-section.

[0022] The electric machine 10 has a rotor 11 with a rotor shaft 12 and a rotor lamination assembly 13 arranged on the rotor shaft 12. The electric machine 10 also has a stator 14, which has a housing 15, a stator lamination assembly 16, and a stator winding 17 housed by the stator lamination assembly 16. The rotor shaft 12 is rotatably supported in the housing 15 by bearings 20.

[0023] Figure 2 The diagram illustrates the three-dimensional arrangement of the stator lamination group 16 and the stator winding 17 housed within it, wherein according to... Figure 1 , Figure 2 The stator winding 17 protrudes relative to the stator laminations 16 on both sides. At the sections of the stator winding 17 that protrude relative to the stator laminations 16, the stator windings 17 are interconnected to form what are called winding heads.

[0024] The stator lamination group 16 is composed of lamination blanks 16a, and similarly, the rotor lamination group 13 is composed of lamination blanks 13a.

[0025] The lamination blank 16a and thus the stator lamination assembly 16 have slots 18 in which stator windings 17 are received. In the stator 14 according to the invention, viewed in a cross-section extending radially in the stator 14, the slots 18 are completely closed radially by connecting members 19 extending circumferentially in the interior. Viewed in a cross-section extending radially in the interior, each of these slots 18 is restricted and thus surrounded on all surfaces by the corresponding lamination blank 16a of the lamination assembly 16, so that the slot 18 is open only at its axial ends, through which the stator windings 17 can be introduced into the slot 18 in the axial direction of the stator 14.

[0026] exist Figure 1 In the cross-section, the axial direction of the stator 14 and therefore the axial direction of the stator lamination 16 of the electric machine 10 are in Figure 1 It extends horizontally in the plane of the diagram. Figure 3 In the illustrated plane, the axial direction of the stator 14 and therefore the axial direction of the stator lamination 16 of the electric machine 10 are perpendicular to the plane. Figure 3The diagram extends in planar direction. The radial direction of stator 14, and therefore the radial direction of stator lamination 16 of motor 10, is... Figure 1 Extending vertically in the plane of the diagram, in Figure 3 It extends in both the horizontal and vertical directions in the plane of the diagram. Therefore, Figure 1 The cross-section can also be referred to as the cross-section extending along the axial direction of the stator 14. The cross-section extending along the radial direction of the stator 14 corresponds to... Figure 3 .

[0027] Figure 3 Not all slots 18 are shown. Other slots connect circumferentially to... Figure 3 The two sides of the slot 18 shown in the figure.

[0028] In the stator 14 according to the invention, the bridging portions 19 of the radially inner closed slots 18 are plastically deformed, more precisely, so that mechanical stress is introduced into these bridging portions. Therefore, it is possible to resist the formation of bearing currents at higher power densities.

[0029] Mechanical stress is introduced in the corresponding bridging portion 19, which is radially confined and radially closed in the corresponding slot 18. This mechanical stress is greater than the yield strength of the material of the bridging portion 19 and therefore greater than the yield strength of the material of the lamination blank 16a of the stator lamination assembly 16.

[0030] Here, viewed in the axial direction of the stator lamination 16, the bridging portion 19 is plastically deformed, more precisely, in such a way as to reduce the axial thickness of the corresponding lamination blank 16a in the region of the corresponding bridging portion 19 by at least section.

[0031] Then, the lamination blanks 16a of the stator lamination assembly 16 are stacked along the axial direction of the stator lamination assembly 16 and flattened together, so that small gaps or free spaces can be generated between the lamination blanks 16a in the region of the bridging portion 19 which is plastically deformed in the axial direction. However, these gaps or free spaces are filled with insulating varnish or adhesive for connecting the lamination blanks 16a into the stator lamination assembly 16.

[0032] This invention relates not only to the stator 14, but also to an electric machine 10 comprising the stator 14 and the rotor 11. The stator 14 is implemented as described above.

[0033] The present invention also relates to a method for manufacturing a stator 14. This is carried out by first providing a sheet material and punching out slots 18 from the provided sheet material to form a laminated blank 16a.

[0034] When the sheet metal is stamped into a laminated blank 16a, the bridging portions 19 remain stationary. These bridging portions radially inward limit and close the slots 18 for accommodating the stator windings 17. The bridging portions 19 of the stator lamination assembly 16 are radially inwardly adjacent to the rotor lamination assembly 13 in such a way as to form an air gap L between the rotor lamination assembly 13 and the stator lamination assembly 16.

[0035] The bridging portion 19 of the stacked blank 16a is plastically deformed. The plastic deformation of the bridging portion 19 can be performed simultaneously with the stamping of the slot 18, or it can be performed after the stamping. In order to plastically deform the bridging portion 19, a punch that deforms the bridging portion 19 in the axial direction can be used.

[0036] After manufacturing a laminated blank 16a having a stamped slot 18 and a bridging portion 19 that is plastically deformed in the axial direction, a limited number of laminated blanks 16a are arranged into a stack, wherein the stack consisting of laminated blanks 16a is pressed together and connected to form a stator lamination group 16.

[0037] Next, the stator winding 17 is arranged in the slot 18 of the lamination blank 16a that is connected to form the stator lamination group 16.

[0038] The present invention reduces the danger of bearing current and the risk of bearing failure caused by bearing current.

[0039] Each slot 18 for accommodating the stator winding 17 is closed by a corresponding bridging portion 19. The bridging portion 19 is plastically deformed. This affects the magnetic properties of the stator lamination 16 in the region of the bridging portion 19.

[0040] The diffusion of eddy current paths in the axial direction is resisted by the insulating layer between the laminated iron core and the laminated blank 16a.

[0041] Finally, it is possible to resist the formation of bearing current while maintaining a high power density in the electric motor 10.

Claims

1. A stator (14) of an electric motor, said stator having: A stator lamination assembly (16) is formed from a lamination blank (16a) having a slot (18) wherein, when viewed in a cross section extending in the radial direction of the stator, the slot (18) is closed radially inward by a bridging portion (19). Stator winding (17), the stator winding being housed in slots (18) of the stator lamination assembly (16), Its features are, The bridging portion (19) that closes the corresponding slot (18) in the radial interior is plastically deformed in such a way that mechanical stress is introduced into the bridging portion, thereby weakening the magnetic properties of the stator laminations in the region of the bridging portion.

2. The stator according to claim 1, characterized in that, Mechanical stress is introduced into the bridging portion (19) that closes the corresponding slot (18) radially inside, and the mechanical stress is greater than the yield strength of the material of the bridging portion (19).

3. The stator according to claim 1 or 2, characterized in that, The free space between the plastically deformed bridging portions (19) of adjacent laminated blanks (16a) along the axial direction is filled with paint or adhesive that connects the laminated blanks (16a).

4. The stator according to any one of claims 1 to 3, characterized in that, The bridging portion (19) is plastically deformed along the axial direction of the stator lamination assembly (16), thereby reducing the thickness of the lamination blank (16a) in the region of the corresponding bridging portion (19) at least in sections.

5. An electric motor, the electric motor having: A rotor (11) and a stator (14), the stator radially surrounding the rotor (11) and thus forming an air gap (L) between the rotor (11) and the stator (14), characterized in that, The stator (14) is designed according to any one of claims 1 to 4.

6. A method for manufacturing a stator (14) according to any one of claims 1 to 5, the method comprising at least the following steps: Provide sheet materials; A laminate blank (16a) with a slot (18) is stamped out from the sheet metal, wherein, when viewed in a cross section extending in the radial direction of the stator, the slot (18) is closed radially inward by a bridging portion (19). Plastic deformation is performed on the bridging portion (19) of the stacked blank (16a); A limited number of stacked blanks (16a) are arranged into a pile; The stack of lamination blanks (16a) is pressed and connected to form the stator lamination assembly (16); The stator winding (17) is arranged in the slot (18) of the lamination blank (16a) that is connected to form the stator lamination group (16).

7. The method according to claim 6, characterized in that, Simultaneously perform the stamping step and the plastic deformation step.

8. The method according to claim 6, characterized in that, The stamping and plastic deformation steps are carried out successively.

9. The method according to any one of claims 6 to 8, characterized in that, When the bridging portion (19) is plastically deformed, the thickness of the lamination blank (16a) in the region of the corresponding bridging portion (19) along the axial direction of the stator lamination group (16) is reduced at least in sections.

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