Electric machine with sealed tube and stator for electric machine

Abstract

The invention relates to an electric machine having a rotor and a stator with a stator lamination stack (15), wherein the stator and the rotor are separated from each other by a sealing tube (20) in order to cool the stator with a liquid coolant. The electric machine comprises a stator component (100) of integral design, which consists of the stator lamination stack (15) and a plastic workpiece (10) molded thereon, wherein the plastic workpiece (10) is designed as a sealing tube (20).

Description

Technical Field

[0001] The invention relates to an electric machine having a sealing tube, a stator for an electric machine, and a method for producing a stator component. Background Art

[0002] The electric motor plays a central role in the electric drivetrains of hybrid, fuel cell, and electric vehicles. The stator of an electric motor typically consists of multiple individual electrical steel sheets stacked and connected together to form a laminated core. Copper windings, which generate the magnetic field, are placed in grooves within this laminated core. The requirements for this laminated core are dictated by the design of the engine and also by the design of the housing into which it is ultimately installed.

[0003] Various winding technologies are known for windings in the stators of electric motors for electric vehicles. In hairpin technology, individual rods are inserted into grooves in the stator lamination stack. The individual rods are then deformed and connected at the ends, in particular by laser welding, to form a continuous winding, the so-called winding head. Because the shorter U-shaped or V-shaped individual segments used for this purpose are reminiscent of a hairpin, such rod-shaped windings are also called hairpin conductors. The advantage of rod-shaped windings is that they can be manufactured fully automatically. The rods typically have a rectangular cross-section and are inserted into correspondingly shaped grooves. In this process, sufficient insulation of the copper conductor (hairpin) from the stator lamination stack must be ensured. Compared to using single wires (as are typically used for winding coils), it is possible to fill the grooves with copper to a greater degree, thus achieving higher machine power within a smaller structural space.

[0004] However, because high engine power also generates high heat losses, direct cooling of the stator windings is necessary to prevent damage to the electric motor. This is typically achieved by using a liquid coolant that flows around the windings. This can be accomplished by providing corresponding cutouts in the rod segments for guiding the coolant, or by providing pipelines through the stator lamination stack. Furthermore, when directly cooling the windings with liquid coolant, a sealing tube is required to separate the stator and rotor to prevent coolant from entering the rotor.

[0005] However, with the growing market share of electric vehicles in recent years, the challenge of developing cost-effective electric motors with high efficiency and quality has also increased. High-efficiency electric motors can, in particular, increase the range of electric vehicles. Furthermore, changes are needed in the production process of electric motors to provide automated and value-added production processes to meet the growing demand for electric vehicles. Environmental considerations, such as improving the recyclability of individual electric motor components, must also be taken into account.

[0006] DE 10 2018 201 626 A1 describes an assembly for an electric motor of a pump, comprising a magnetically conductive hollow cylindrical star having a plurality of radially outwardly projecting and axially extending teeth on the outside for accommodating a toroidal coil of a winding. An insulating structure formed of a magnetically neutral and electrically insulating insulating material is molded onto the star.

[0007] DE 10 2008 019 608 A1 describes an insulation carrier consisting of an inner cylindrical hollow body for receiving a rotor of an electric motor. The insulation carrier has a circumferential groove on its outer side for receiving a coil winding.

[0008] DE 10 2013 109 522 A1 describes a pump having a sealed tube motor with a stator and an inner rotor arranged therein, wherein the stator and the inner rotor are separated from each other in a liquid-tight manner by a sealing tube arranged between the stator and the inner rotor. The sealing tube is provided with conical ribs that engage with the stator in a form-fitting manner.

[0009] WO 2019 238 365 A1 describes an electric motor having a sealing tube between the stator and the rotor, wherein the sealing tube is made of a ferrite material. Summary of the Invention

[0010] The object of the present invention is therefore to provide an electric machine having a sealing tube which is distinguished by a compact design and which can be produced in an automated and cost-effective manner.

[0011] According to the invention, this object is achieved with respect to the electric machine by the following features of the electric machine according to a first aspect, with respect to the stator by the following features of a stator for an electric machine according to a second aspect, and with respect to the method by the following features of a method for producing a stator component according to another aspect. Further improved, advantageous embodiments relate to preferred embodiments of the invention.

[0012] According to a first aspect, the present invention relates to an electric machine having a rotor and a stator including a stator lamination stack. The rotor and stator are separated from one another by a sealing tube for cooling the stator with a liquid coolant. The electric machine includes a one-piece stator component consisting of the stator lamination stack and a plastic workpiece molded thereon, the plastic workpiece being designed as a sealing tube.

[0013] In a development, it is provided that the plastic workpiece consists of a magnetically neutral and electrically insulating plastic, epoxy resin being particularly suitable here due to its high mechanical strength, and is injection-molded onto the stator laminated core by means of an injection molding or transfer molding method.

[0014] Advantageously, a plurality of insulating sleeves for receiving the conductor bars annularly surround the outer surface of the sealing tube.

[0015] In particular, the insulating sleeve encloses a groove for receiving the conductor bar.

[0016] In another embodiment, the insulating sleeve has two side walls connected to the outer surface of the sealing tube at their bottom end edges, and the insulating sleeve has an outer wall connected to the top end edges of the side walls, and the two side walls and the outer wall together form a groove.

[0017] In particular, segments of the stator laminated core are arranged in the spaces between adjacent insulating bushings.

[0018] In a further embodiment, an end disk is provided in the top end region and / or in the bottom end region of the sealing tube.

[0019] In particular, the end disk is connected in one piece to the outer surface of the insulating sleeve and / or the outer surface of the sealing tube.

[0020] Advantageously, the end disc has recesses and / or openings for mounting and fixing the conductor tracks.

[0021] According to a second aspect, the invention relates to a stator for an electric machine, the stator having a stator lamination stack. The stator comprises a one-piece stator component consisting of the stator lamination stack and a plastic workpiece molded thereon, wherein the plastic workpiece is designed as a sealing tube.

[0022] In an advantageous embodiment, the plastic workpiece consists of a magnetically neutral and electrically insulating plastic and is injection-molded onto the stator sheet metal part by means of an injection molding method or a transfer molding method.

[0023] According to another aspect, the present invention relates to a method for producing a stator component, wherein a stator laminated core made of a magnetically neutral and electrically insulating plastic is overmolded in a mold by means of an injection molding or transfer molding method in such a way that a plastic workpiece connected to the stator laminated core is produced, wherein the plastic workpiece forms a sealing tube for the conductor track and an insulating sleeve molded thereon. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The invention is explained in more detail below with reference to an exemplary embodiment shown in the drawings.

[0025] In the attached figure:

[0026] Figure 1 A schematic perspective view shows a stator component for an electric machine according to the present invention, the stator component consisting of a laminated core and a plastic workpiece;

[0027] Figure 2A schematic perspective view of a plastic workpiece is shown, which consists of a sealed tube with a molded insulating sleeve;

[0028] Figure 3 Show Figure 2 A schematic cross-sectional view of a plastic workpiece;

[0029] Figure 4 Show Figure 2 Schematic perspective view of a plastic workpiece with a molded end disc and an insulating sleeve. DETAILED DESCRIPTION

[0030] Additional features, aspects, and advantages of the present invention or its embodiments will be apparent from the detailed description taken in conjunction with the claims.

[0031] Figure 1 A schematic diagram shows a first embodiment of a stator component 100 for a stator of an electric machine, particularly an electric motor. Stator component 100 consists of a plastic workpiece 10 and a stator lamination stack 15. Plastic workpiece 10 includes a sealing tube 20, an insulating sleeve 30, and a top end disc 40 and / or a bottom end disc 42. Stator component 100 is part of the stator of an electric machine (not shown in detail here), which includes a stator and a rotor. The rotor is arranged in a receiving space formed by the stator. The electric machine is preferably used as a traction motor in an electric vehicle.

[0032] The stator laminated core 15 is placed in a mold and then overmolded with plastic using an injection molding or transfer molding method to produce a plastic workpiece 10. The stator component 10 is thus a composite of the stator laminated core 15 and the plastic workpiece 10 fixedly connected thereto by overmolding. The plastic workpiece 10 is made of a magnetically neutral and electrically insulating plastic, such as PA (polyamide), PP (polypropylene), and / or PS (polystyrene).

[0033] like Figure 2 As shown, the plastic workpiece 10 has a hollow cylindrical sealing tube 20, which, when the electric machine is assembled, is arranged in the air gap between the rotor and the stator and separates the stator from the rotor. This is particularly necessary when the stator is cooled by means of a liquid coolant. Insulating sleeves 30 for receiving conductor bars (hairpins), preferably made of copper, are integrally formed on the outer surface 22 of the sealing tube 20. These sleeves preferably surround the outer surface 22 in an annular manner and, in particular, each point radially outward.

[0034] like Figure 3As shown, the insulating sleeves 30 enclose a groove 32 and extend parallel to the longitudinal axis of the sealing tube 20. The groove has a preferably rectangular cross-section for receiving a conductor bar, which is also rectangular in cross-section. Each insulating sleeve 30 has two side walls 34 connected to the outer surface 22 of the sealing tube 20 at their bottom end edges, and an outer wall 36 connected to the top end edges of the side walls 34. Together, the side walls and the outer wall form the groove 32 for receiving the conductor bar. Profiles for the coolant flow may also be provided in the groove 32. However, it is also possible for the conductor bar to be provided with profiles for the coolant. Segments of the stator laminated core 15 (not shown in detail here) are arranged in the interspace 38 between the insulating sleeves 30.

[0035] exist Figure 4 , a plastic workpiece 10 is shown having a top end disc 40 and a bottom end disc 42. The top end disc 40 is arranged in the top end region of the sealing tube 20, and the bottom end disc 42 is arranged in the bottom end region of the sealing tube 20. The top end disc 40 and the bottom end disc 42 are preferably designed identically, so that the stator component 100 is symmetrically constructed. However, it is also conceivable that the top end disc 40 and the bottom end disc 42 are designed differently from each other. However, it is also possible for the plastic workpiece 10 to have only the end disc 40.

[0036] Preferably, the end discs 40, 42 are annular in shape and are molded onto the outer surface 22 of the sealing tube 20 or the outer surface of the insulating sleeve 30. The end discs 40, 42 particularly have recesses 44 and / or openings for mounting and securing the conductors. This simplifies the shaping and welding of the conductors into winding heads during assembly of the electric machine, since the end discs 40, 42 secure the conductors, and this method step can therefore be performed automatically using a robot.

[0037] The one-piece stator component 100, consisting of the stator lamination stack 15 and the plastic workpiece 10 molded thereon, provides a composite component distinguished by a significant reduction in the number of required components. Plastic overmolding of the stator lamination stack 15 eliminates the need for multiple materials, as, for example, insulating paper strips are no longer required for the grooves 32. The conductor paths are electrically isolated from the stator lamination stack 15 by being surrounded by the insulating sleeve 30, eliminating the need for additional material. This simplifies the stator manufacturing process due to the reduced number of components that must be assembled. Furthermore, this improves recyclability.

[0038] Furthermore, due to the reduced number of components, weight can be reduced, and more cost-effective base materials can be used. The fixed connection of the stator lamination stack 15 to the plastic workpiece 10 also results in higher strength for the stator component 100. This allows for a reduced wall thickness for the sealing tube 20, which in turn reduces the air gap between the stator and rotor. A smaller air gap, in turn, increases the efficiency of the electric machine.

[0039] In particular, filling the cavities with plastic overmolding can compensate for manufacturing tolerances of the segments of the stator laminate 15 , resulting in a stator component 100 that is characterized by a high degree of standardization and a high surface quality. Since the stator component 100 is provided with two end discs 40 , 42 , arranged at the top and bottom end regions of the sealing tube 20 , the assembly of the conductor tracks can be simplified. This can thus reduce the number of method steps overall, thereby enabling more efficient production and, consequently, cost savings. This overall contributes to more cost-effective and environmentally friendly production of electric motors.

Claims

1. An electric machine having a rotor and a stator including a stator lamination stack (15), wherein the rotor and the stator are separated from each other by a sealing tube (20) so that the stator can be cooled with a liquid coolant, characterized in that A stator component (100) of integral design is composed of the stator lamination stack (15) and a plastic workpiece (10) molded thereon, wherein the plastic workpiece (10) is designed as the sealing tube (20), a plurality of insulating sleeves (30) for receiving conductor bars annularly surround the outer surface (22) of the sealing tube (20), and the insulating sleeves (30) form a groove (32) for receiving the conductor bars, and wherein a molded portion for flowing the liquid coolant is provided in the groove (32), or the conductor bars are provided with a molded portion for the liquid coolant.

2. The electric machine according to claim 1, wherein the plastic workpiece (10) consists of a magnetically neutral and electrically insulating plastic and is injection-molded onto the stator lamination stack (15) by means of an injection molding method or a transfer molding method. 3 . The electric machine according to claim 2 , wherein the magnetically neutral and electrically insulating plastic comprises PA (polyamide), PP (polypropylene) and / or PS (polystyrene).

4. An electric machine according to any one of claims 1 to 3, wherein the insulating sleeve (30) has two side walls (34), the side walls being connected to the outer surface (22) of the sealing tube (20) at their bottom end edges, and the insulating sleeve has an outer wall (36) connected to the top end edges of the side walls (34), the side walls and the outer wall together forming the groove (32).

5. The electric machine according to claim 1, wherein segments of the stator laminate core (15) are arranged in intermediate spaces (38) between adjacent insulating bushings (30).

6. The electric machine according to any one of claims 1 to 3, wherein an end disc (40, 42) is provided in the top end region and / or the bottom end region of the sealing tube (20).

7. The electric machine according to claim 6, wherein the end disc (40, 42) is integrally connected to the outer surface of the insulating sleeve (30) and / or the outer surface (22) of the sealing tube (20).

8. The electric machine according to claim 6, wherein the end disc (40, 42) has recesses (44) and / or openings for mounting and fixing conductor tracks.

9. A stator for an electric machine, the stator having a stator lamination stack (15), characterized in that A stator component (100) of integral design is composed of the stator lamination stack (15) and a plastic workpiece (10) molded thereon, wherein the plastic workpiece (10) is designed as a sealing tube (20), a plurality of insulating sleeves (30) for receiving conductor bars annularly surround the outer surface (22) of the sealing tube (20), and the insulating sleeves (30) form a groove (32) for receiving the conductor bars, and wherein a molded portion for flowing a liquid coolant is provided in the groove (32), or the conductor bars are provided with a molded portion for the liquid coolant.

10. The stator according to claim 9, wherein the plastic workpiece (10) consists of a magnetically neutral and electrically insulating plastic and is injection-molded onto the stator core (15) by means of an injection molding method or a transfer molding method. 11 . The stator according to claim 10 , wherein the magnetically neutral and electrically insulating plastic comprises PA (polyamide), PP (polypropylene) and / or PS (polystyrene).

12. A method for producing a stator component (100), wherein a stator lamination stack (15) made of a plastic material consisting of a magnetically neutral and electrically insulating plastic material is overmolded in a mold by means of an injection molding method or a transfer molding method, in such a way that a plastic workpiece (10) connected to the stator lamination stack (15) is produced, wherein the plastic workpiece (10) forms a sealing tube (20) for a conductor line and an insulating sleeve molded thereon, a plurality of insulating sleeves for receiving conductor bars annularly surround the outer surface (22) of the sealing tube (20), and the insulating sleeves enclose a groove (32) for receiving the conductor bars, and wherein A shaped portion for a liquid coolant to flow through is provided in the groove (32), or the conductor bar is provided with a shaped portion for the liquid coolant.

13. The method for producing a stator component (100) according to claim 12, wherein the magnetically neutral and electrically insulating plastic comprises PA (polyamide), PP (polypropylene) and / or PS (polystyrene).

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