STATOR FOR AN ELECTRIC MACHINE AND METHOD FOR MANUFACTURING A STATOR FOR AN ELECTRIC MACHINE

Abstract

A stator for an electric machine and a method for its manufacture are specified, said electric machine having a laminated core around an axial direction that, in a first overmoulding between a first axial end and a second axial end, is surrounded by a first plastic material having several grooves, into which the stator windings having a first winding head and a second winding head that are connected to several connecting contacts are supplied, wherein in a second overmoulding, a second plastic material fills the grooves around the stator windings and at least covers regions outside of the first winding head on the first axial end and outside of the second winding head on the second axial end.

Claims

1. A stator for an electric machine, having a laminated core around an axial direction that, in a first overmoulding between a first axial end and a second axial end, is surrounded by a first plastic material having several grooves, into which the stator windings having a first winding head and a second winding head that are connected to several connecting contacts are supplied, wherein in a second overmoulding, a second plastic material fills the grooves around the stator windings and at least covers regions outside of the first winding head on the first axial end and outside of the second winding head on the second axial end.

2. The stator according to claim 1, in which the grooves are arranged along the axial direction and are formed open on an inner side, wherein the stator windings are formed as wild windings with a retraction winding technique in the grooves.

3. The stator according to claim 1, in which the second winding head is provided with a protective cap on the second axial end that is covered by a second plastic material.

4. The stator according to claim 1, in which the connecting contacts are arranged on the first axial end and fixed in a positioning disc that covers the first winding head of the stator windings on the first axial end.

5. The stator according to claim 1, in which the first plastic material is formed such that the stator laminated core is electrically insulated from the stator windings in the axial direction, preferably by a spacer formed from the first plastic material on end faces on both axial ends.

6. The stator according to claim 1, in which the properties of the first plastic material or the second plastic material are coordinated with each other with regards to their flow properties and their thermal conductivity.

7. The stator according to claim 1, in which the first axial end and the second axial end are connected to temporary channels made of second plastic material in order to transfer the second plastic material from the region of the positioning disc to the region of the protective cap in a fluid form during manufacture.

8. The stator according to claim 1, in which the first plastic material is formed as a liquid crystalline polymer having a mineral filling, and preferably has a thermal conductivity of approximately 9 W/mK.

9. The stator according to claim 1, in which the second plastic material is modified with regards to its thermal conductivity, and is in particular formed as polyphenylene sulphide, and preferably has a thermal conductivity of approximately 2 W/mK.

10. A method for manufacturing a stator for an electric machine, in which the following steps are carried out: provision of a stator laminated core, carrying out of a first overmoulding of the stator laminated core having several grooves made from a first plastic material formed along an axial direction, insertion of stator windings in the grooves, forming of the winding heads on the two sides, connection of the stator windings having several connecting contacts, and carrying out of a second overmoulding to fill the grooves around the stator windings with second plastic material.

11. The method according to claim 10, in which the following further steps are carried out before the second overmoulding is carried out: fixing of the connecting contacts in a positioning disc covering a first axial end, and covering of an opposite second axial end having a protective cap.

12. The method according to claim 11, in which the step of carrying out the second overmoulding is carried out in an injection mould in such a way that the positioning disc is fixed together with the connecting contacts, preferably via holding grooves, in an injection mould.

13. The method according to claim 11, that is carried out during the step of carrying out the second overmoulding in such a way that temporary channels are formed in the injection mould between the first axial end and the second axial end in order to transfer the second plastic material from the region of the positioning disc to the region of the protective cap in a fluid form.

14. An electric motor having a stator according to claim 1.

15. A charging device for an internal combustion machine, in particular in a vehicle, wherein the charging device has a compressor driven by an electric motor or an electric motor optionally also operable as a generator or a turbine-driven compressor, wherein the electric motor is formed having a stator according to claim 1.

Description

BRIEF DESCRIPTION

[0049] Several exemplary embodiments are described in more detail in the following with reference to the drawing, in which:

[0050] FIG. 1 shows a charging device for an internal combustion machine in a cross-sectional depiction,

[0051] FIG. 2 shows an embodiment of a stator according to the invention in a cross-sectional view,

[0052] FIG. 3 shows the stator according to the invention from FIG. 2 in a side view,

[0053] FIG. 4 shows a detailed view of the stator according to the invention from FIG. 2 in a cross-sectional view,

[0054] FIG. 5 shows the stator according to the invention from FIG. 2 in a perspectival side view,

[0055] FIG. 6 shows the stator according to the invention from FIG. 2 in a perspectival exploded depiction after going through the method steps for its manufacture.

DETAILED DESCRIPTION

[0056] Identical components or components functioning in an identical manner are provided with the same reference numerals in the figures.

[0057] A charging device 1 according to an embodiment is described in detail in the following with reference to FIG. 1, in which the stator according to the invention can preferably be used. A use in a charging device 1 of this kind is only provided in an exemplary form, however, as other usage cases of the stator according to the invention would also be possible.

[0058] FIG. 1 shows the charging device 1 in a cross-sectional view, comprising a compressor 2. The compressor 2 has a compressor housing 3. A compressor wheel 4 is arranged in the compressor housing 3. This compressor wheel 4 is located in the so-called compressor chamber. The charging device 1 further comprises an electric motor 5. The electric motor 5 is composed of a rotor 6 and a stator 7. The rotor 6 is rotationally connected to the compressor wheel 4 via a shaft 8. The compressor wheel 4 is thus set in rotation by rotating the rotor 6. The compressor wheel 4 and the rotor 6 are arranged coaxially, such that the shaft 8 is simultaneously also the rotor shaft.

[0059] Air is sucked in the axial direction when the rotor 6 rotates, and thus when the compressor wheel 4 rotates. The air is compressed in the radial direction via the compressor 2, and an internal combustion machine is supplied.

[0060] The charging device 1 further comprises a motor housing 9. A motor chamber 10 is formed in this motor housing 9. The motor chamber 10 is closed by means of a lid 12 on the side turned away from the compressor 2. The motor chamber 10 is delimited by a wall 11 of the motor housing 9 up to the compressor 2. The compressor housing 3 is open on its side facing the motor housing 9. This open side is closed by means of a back wall 13. Means (not shown) that provide a defined axial positioning of the back wall 13 relative to the compressor housing can be provided on the back wall 13 on a side facing the compressor 2.

[0061] The motor housing 9 is fixedly connected to the compressor housing 3 with its wall 11, in particular screwed. An intake chamber 14 is here formed between the back wall 13 and the wall 11. Power electronics 15 for providing power and controlling the electric motor 5 are located in this intake chamber 14. The intake chamber 14 is hermetically sealed in relation to the compressor chamber and in relation to the motor chamber 10.

[0062] An embodiment of the stator 7 according to the invention is shown in a side view in FIG. 2. The stator 7 comprises a typically cylindrical stator laminated core 16 that is arranged around an axial direction 17 that runs within the stator 7. The stator laminated core 16 is provided with a first plastic material 18 as a first overmoulding that has a plurality of grooves 19 on the inner side towards the axial direction 17 that are also arranged substantially in parallel to the axial direction 17. Stator windings 20 (only depicted schematically in FIG. 2) are installed in the grooves 19, which end on a first axial end 21 in several connecting contacts 22. The connecting contacts 22 are connected to the stator windings 20, for example by means of clamping (crimping).

[0063] A positioning disc 23 is arranged on the first axial end 21 that is used to receive and fix the connecting contacts 22. The stator windings 20 usually respectively have a winding head both on their side facing the first axial end 21 and on their side facing a second axial end 24, said winding head connecting the stator windings running along the grooves 19 to one another. The winding head is schematically labelled in FIG. 2 with the reference numeral 25 for the first winding head or 26 for the second winding head.

[0064] Spacers are formed by means of the first plastic material in order to prevent electrical short-circuits between the stator laminated core 16 and in particular the first winding head 25, said spacers holding the first winding head 25 spaced apart from the stator laminated core 16. The stator 7 is embedded in a second plastic material 28 that is implemented as a second overmoulding, such that the positioning disc 23 is implemented as a one-piece component with the remaining components together with the connecting contacts 22, wherein the second overmoulding either covers the second winding head, or otherwise at least partially overmoulds a protective cap 30 as shown in FIG. 2 in the region of the second axial end 24. The stator windings 20 are likewise filled by the second plastic material 28 within the grooves 19.

[0065] As a result, a compact stator 7 is obtained, in which the stator windings 20 are protected outwards by means of the second plastic material 28 and the positioning disc 23 or the protective cap 30, and the positions of the connecting contacts 22 are precisely determined via the positioning disc 23.

[0066] A space-saving construction of the stator 7 can be obtained due to the first overmoulding with the first plastic material 18, which functions as a spacer, as the groove insulation paper known from the prior art can be dispensed with as paper insulation between the stator laminated core 16 and the stator windings 20. A stator 7 constructed in this manner additionally has better thermal properties, as a correspondingly high thermal conductivity can be obtained in particular via the selection of the first plastic material 18 and the second plastic material 28. The usage of plastic materials additionally allows a mechanically stable construction that has a good insulation from the environment.

[0067] The first plastic material 18 is formed as a liquid crystalline polymer having a mineral filling. The first plastic material 18 can here have a thermal conductivity of approximately 9 W/mK.

[0068] The second plastic material 28 is modified with regards to its thermal conductivity, and can in particular be formed as a thermoplastic material, preferably polyphenylene sulphide (PPS). The second plastic material 28 can here have a thermal conductivity of approximately 2 W/mK.

[0069] The specified plastic materials for the first plastic material 18 and the second plastic material 28 having the cited specifications enable manufacturing with applied pressure via injection moulding methods carried out one after another. The cycle times of the combined process steps are here significantly reduced in comparison with conventional casting.

[0070] In FIG. 3, the stator 7 is shown in a side view. It can be seen that the outer side of the second plastic material 28 and the connecting contacts 22 and the positioning disc 23 are formed in addition to the stator laminated core 16. The second overmoulding with the second plastic material 28 occurs in an injection mould provided for the purpose, wherein the positioning disc 23 can be installed in the injection mould via holding grooves 29 lying radially outwards, such that the fixing of the positioning disc 23, and consequently also the connecting contacts 22, can occur with high precision and in particular in a reproducible manner. This simplifies the further use of the stator 7 significantly, as components corresponding to the connecting contacts 22 can provide lower intake tolerances. The waste of components in the further construction of an electric machine, e.g., the electric motor 5 described above, is thus also reduced.

[0071] The arrangement of the stator windings 20 within the grooves 19 is explained again in more detail in connection with FIG. 4. The depiction according to FIG. 4 represents a cut through the stator laminated core 16 together with the first overmoulding from the first plastic material 18, which is substantially shown perpendicularly to the axial direction 17 in a slightly perspectival depiction. It can be seen that the stator winding 20 is formed as a so-called wild winding by means of retraction winding technique, wherein the stator windings 20 are arranged within the grooves 19. The grooves 19 are filled with the second plastic material 28. The first plastic material 18 thus forms the part of the stator 7 that receives the stator winding 20 together with the stator laminated core 16, wherein the second overmoulding with the second plastic material 28 contributes outwardly for the electrical insulation and the thermal conductivity.

[0072] In FIG. 5, the stator 7 is shown again in a perspectival side view after all the method steps have ended. In order to obtain an even distribution of the second plastic material 28 in fluid form, it is provided that corresponding channels are formed in the injection moulding tool that reach from the region of the positioning disc 23 to the protective cap 30, such that when the fluid plastic material is introduced from the first axial end 21, this does not need to be pressed through the grooves 19 in order to be able to reach the second axial end 24. It can thus be ensured that the second plastic material 28 can fill all the cavities between the first axial end 21 and the second axial end 24 before it cools. The temporary channels created here are labelled with the reference numeral 32 in FIG. 5. These channels can easily be split by a corresponding formation on the transition to the outer side of the stator 7, as they are unnecessary for the later function of the stator 7.

[0073] The complete construction of the stator 7 is shown again in an exploded depiction with reference to FIG. 6. The arrangement of the stator laminated core 16 and the first plastic material 18 as first overmoulding having the grooves 19 formed in it can be seen lying approximately in the centre. The stator winding 20 is only schematically depicted in turn. The grooves 19 are further covered with the so-called slot wedges 33 from the inner side. The stator windings 20 are connected to the connecting contacts 22 in the direction of the first axial end 21. The positioning disc 23 forms the end on the first axial end. The protective cap 30 is located on the opposite side of the second axial end 24. The second overmoulding formed from the second plastic material 28 is schematically depicted with all its components, including the temporary channels 32 on the right image side.

[0074] In a manufacturing method according to the invention, the stator laminated core 16 is first provided with the first overmoulding of first plastic material 18, such that grooves 19 for receiving the stator windings 20 formed by means of retraction winding technique are created that are connected to the connecting contacts 22. The two axial ends 21, 24 are covered by the positioning discs 23 having the connecting contacts 22 fixed within them and the protective cap 30, such that the outer regions around the protective cap 30 and the positioning disc 23 are covered by second plastic material 28 when the grooves 19 around the stator windings 20 are simultaneously filled after a second overmoulding, such that the stator 7 forms a one-piece component overall. As the overmouldings are formed by an injection moulding method, a clear reduction of the cycle times in comparison with conventional casting in the manufacture of the stator 7 for an electric machine results.

[0075] The features specified previously and in the claims, and which can be understood from the figures, can be advantageously provided both individually and in different combinations. The invention is not limited to the exemplary embodiments described, but can be modified within the scope of the ability of a person skilled in the art in several ways.

REFERENCE NUMERALS

[0076] 1 charging device [0077] 2 compressor [0078] 3 compressor housing [0079] 4 compressor wheel [0080] 5 electric motor [0081] 6 rotor [0082] 7 stator [0083] 8 shaft [0084] 9 motor housing [0085] 10 motor chamber [0086] 11 wall [0087] 12 lid [0088] 13 back wall [0089] 14 intake chamber [0090] 15 power electronics [0091] 16 stator laminated core [0092] 17 direction [0093] 18 first plastic material [0094] 19 grooves [0095] 20 stator winding [0096] 21 first axial end [0097] 22 connecting contact [0098] 23 positioning disc [0099] 24 second axial end [0100] 25 first winding head [0101] 26 second winding head [0102] 27 spacer made of first overmoulding material [0103] 28 second plastic material [0104] 29 holding grooves [0105] 30 protective cap [0106] 32 temporary channel [0107] 33 slot wedge