ELECTRIC MACHINE WITH A CAN, AND STATOR FOR AN ELECTRIC MACHINE

Abstract

An electric machine has a rotor and a stator defined by a stator laminated core (15). The rotor and the stator are separated from one another by a can (20) for the cooling of the stator using a liquid coolant. The electric machine has a stator component (100) formed as a single piece and composed of the stator laminated core (15) and of a plastics work-piece (10) molded thereon. The plastics workpiece (10) is formed as the can (20).

Claims

1. An electric machine comprising: a rotor and a stator having a stator laminated core (15), the rotor and the stator being separated from one another by a can (20) for cooling the stator using a liquid coolant, a stator component (100) formed as a single piece and composed of the stator laminated core (15) and a plastics workpiece (10) molded thereon, wherein the plastics workpiece (10) is formed as the can (20).

2. The electric machine of claim 1, wherein the plastics workpiece (10) is composed of a magnetically neutral and electrically insulating plastic and is molded onto the stator laminated core (15) by an injection molding process or a transfer molding process.

3. The electric machine of claim 2, wherein the magnetically neutral and electrically insulating plastic is polyamide.

4. The electric machine of claim 2, wherein the magnetically neutral and electrically insulating plastic is polypropylene.

5. The electric machine of claim 2, wherein magnetically neutral and electrically insulating plastic is polystyrene.

6. The electric machine of claim 1, wherein plural insulating sleeves (30) for receiving conductor bars surround an outer surface (22) of the can (20) in ring-shaped fashion.

7. The electric machine of claim 6, wherein the insulating sleeves (30) enclose form grooves (32) for receiving the conductor bars.

8. The electric machine of claim 6, wherein the insulating sleeve (30) has two side walls (34) connected at their lower end edges to the outer surface (22) of the can (20), and one outer wall (36) that is connected to the upper end edges of the side walls (34), the side walls and outer wall collectively forming the groove (32).

9. The electric machine of claim 1, wherein segments of the stator laminated core (15) are arranged in the intermediate spaces (38) between the adjacent insulating sleeves (30).

10. The electric machine of claim 1, wherein an end disk (40, 42) is provided in the upper end region and/or in the lower end region of the can (20).

11. The electric machine of claim 10, wherein the end disk (40, 42) is connected integrally to the outer surfaces of the insulating sleeves (30) and/or to the outer surface (22) of the can (20).

12. The electric machine of claim 10, wherein the end disk (40, 42) has recesses (44) and/or openings for the installation and fixing of the conductor tracks.

13. A stator for an electric machine, comprising a stator laminated core (15) having a stator component (100) formed as a single piece and composed of the stator laminated core (15) and a plastics workpiece (10) molded thereon, wherein the plastics workpiece (10) is formed as the can (20).

14. The stator of claim 13, wherein the plastics workpiece (10) is composed of a magnetically neutral and electrically insulating plastic and is molded onto the stator laminated core (15) by an injection molding process or a transfer molding process.

15. The stator of claim 14, wherein the magnetically neutral and electrically insulating plastic is polyamide.

16. The stator of claim 14, wherein the magnetically neutral and electrically insulating plastic is polypropylene.

17. The stator of claim 14, wherein magnetically neutral and electrically insulating plastic is polystyrene.

18. A method for producing a stator component (100), the method comprising: providing a stator laminated core (15); overmolding the stator laminated core (15) with a plastic composed of a magnetically neutral and electrically insulating plastic by an injection molding process or a transfer molding process in a tool and thereby forming a plastics workpiece (10) that is connected to the stator laminated core (15), wherein the plastics workpiece (10) forms a can (20) with insulating sleeves being formed on the can for conductor tracks.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 is a schematic perspective view of a stator component according to the invention composed of a laminated core and a plastics workpiece for an electric machine.

[0023] FIG. 2 is a schematic perspective view of the plastics work piece composed of a can with integrally formed insulating sleeves.

[0024] FIG. 3 is a schematic cross-sectional view of the plastics workpiece of FIG. 2.

[0025] FIG. 4 is a schematic perspective iview of the plastics workpiece of FIG. 2 with end disks and insulating sleeves formed thereon.

[0026] Additional features, aspects and advantages of the invention or its exemplary embodiments will become apparent from the detailed description in conjunction with the claims.

DETAILED DESCRIPTION

[0027] FIG. 1 is a schematic illustration of a first embodiment of a stator component 100 for a stator of an electric machine, in particular of an electric motor. The stator component 100 is composed of a plastics workpiece 10 and a stator laminated core 15. The plastics workpiece 10 comprises a can 20, insulating sleeves 30 and an upper end disk 40 and/or a lower end disk 42. The stator component 100 is a component of a stator of an electric machine (not illustrated in any more detail here). The electric machine comprises the stator and a rotor. The rotor is arranged in a receiving space formed by the stator. The electric machine may be used as a traction electric motor in an electric vehicle.

[0028] The stator laminated core 15 is placed into a tool and is then overmolded with plastic by way of an injection molding process or a transfer molding process to from the plastics workpiece 10. The stator component 10 is thus a composite part composed of the stator laminated core 15 and the plastics workpiece 10 fixedly connected thereto by overmolding. The plastics workpiece 10 is composed of a magnetically neutral and electrically insulating plastic, for example PA (polyamide), PP (polypropylene) and/or PS (polystyrene).

[0029] As illustrated in FIG. 2, the plastics workpiece 10 has a hollow cylindrical can 20 which, in the assembled state of the electric machine, is arranged in an air gap between the rotor and the stator and separates the stator from the rotor. This is necessary if the stator is cooled using a liquid coolant. Insulating sleeves 30 for receiving conductor bars (hairpins) are formed on an outer surface 22 of the can 20 and in some embodiments are composed of copper. The insulating sleeves of the illustrated embodiment surround the outer surface 22 in ring-shaped fashion and are directed radially outward.

[0030] As illustrated in FIG. 3, an insulating sleeve 30 encloses a groove 32 with a rectangular cross section for receiving a conductor bar that also is of rectangular cross section, and extends parallel to the longitudinal axis of the can 20. Each insulating sleeve 30 has two side walls 34 that are connected at their lower end edges to the outer surface 22 of the can 20. One outer wall 36 is connected to the upper end edges of the side walls 34 so that the side walls 34 and the outer wall 36 collectively form the groove 32 for the insertion of a conductor bar. Formations for the throughflow of a coolant may also be provided in the grooves 32. It is however also possible for the conductor bars to be provided with formations for a coolant. The segments of the stator laminated core 15 (not illustrated in any more detail here) are arranged in the intermediate spaces 38 between the insulating sleeves 30.

[0031] FIG. 4 illustrates the plastics workpiece 10 with the upper end disk 40 and the lower end disk 42. The upper end disk 40 is arranged in the upper end region of the can 20, and the lower end disk 42 is arranged in the lower end region of the can 20. In particular, the upper end disk 40 and the lower end disk 42 are identical so that the stator component 100 is of symmetrical construction. It is however conceivable for the upper end disk 40 and the lower end disk 42 to be designed differently from one another. The plastics workpiece 10 of some embodiments may have only one end disk 40.

[0032] The end disks 40, 42 are annular and are formed on the outer surface 22 of the can 20 and/or the outer surfaces of the insulating sleeves 30. In particular, the end disks 40, 42 have recesses 44 and/or openings for the installation and fixing of the conductor tracks. In this way, the deformation and welding of the conductor tracks to form a winding head during the assembly of the electric machine can be simplified, because the end disks 40, 42 are used for fixing the conductor tracks. This method step can be performed in automated fashion with the aid of robots.

[0033] The stator component 100 is formed as a single piece and is composed of the stator laminated core 15 and the plastics workpiece 10 molded thereon. The stator component 100 forms a composite part that is distinguished by a major reduction of the components required. By virtue of the stator laminated core 15 being overmolded with plastic, the use of a large number of materials can be dispensed with, for example because there is no need for insulating paper strips for the grooves 32. The insulator sleeves 30 amply isolate the conductor tracks electrically from the stator laminated core 15, such that no further materials are necessary. In this way, the production process of the stator is simplified, because fewer components have to be assembled. Furthermore, recyclability is increased as a result.

[0034] A low weight is made possible due to the smaller number of components, and less expensive base materials. The firm connection of the stator laminated core 15 to the plastics workpiece 10 furthermore results in greater strength of the stator component 100. In this way, the wall thickness of the can 20 can be reduced, and this in turn leads to a reduction of the air gap between the stator and the rotor. A small air gap however increases the efficiency of the electric machine.

[0035] Manufacturing tolerances of the segments of the stator laminated core 15 can be compensated by virtue of cavities being filled with the plastics overmolding, such that the produced stator components 100 are distinguished by a high level of standardization and high surface quality. The stator component 100 can be equipped with two end disks 40, 42 arranged respectively at the upper and lower end regions of the can 20. Thus, the installation of the conductor tracks can be simplified. Altogether, the number of method steps can thus be reduced so that a more efficient production and a cost saving can be achieved. This leads overall to less expensive and more environmentally friendly production of an electric motor.