Stator having winding grooves closed by foaming sealing material, electric motor having a stator and sealing with direct groove cooling by (partially) coated insulation components with foaming material

Abstract

The invention relates to a stator (1) for an electric motor, having a stator body (2) that has winding grooves (3) provided for receiving a winding (4), having at least one cover slide (6) for closing at least one of the winding grooves (3), a flat insulator (7) being provided in the winding groove (3) for spacing the winding (4) from the stator body (2), wherein a sealing material (9) that foams when heat is applied is present exclusively on at least one edge region (11) of the flat insulator (7), said sealing material being delimited on this edge region (11), and / or such a sealing material (9) that foams when heat is applied is present on the cover slide (6). The invention also relates to an electric motor having a rotor arranged within such a stator (1).

Description

[0001] P241519

[0002] - 1 -

[0003] Stator with winding slots sealed by foaming sealing material, electric motor with stator and sealing in slot direct cooling by (partially) coated insulation components with foaming material

[0004] The invention relates to a stator for an electric motor, which can be used, for example, as a drive unit in a motor vehicle powertrain. Such a stator has a stator body which in turn has a plurality of winding slots. These winding slots can also be referred to as cooling slots. These winding slots are provided for receiving a winding. Such a winding can, for example, have hairpins or be constructed from them. The stator body also has at least one rotary valve, or preferably a plurality of rotary valves, which are used to close at least one of the winding slots, for example, radially inwards. In at least one of the winding slots, preferably all winding slots, there is (each) a planar insulator, such as slotted paper, for spacing the winding from the stator. The slotted paper is also referred to as slot insulation paper.It is desirable to use an insulating material with an electrical permittivity between 1 and 5 as a planar insulator.

[0005] The invention relates to slot direct cooling and wave windings or shaped coils. The invention thus relates to the process of slot insulation on a stator, the slot insulation itself, and the stator itself.

[0006] The state of the art is known, for example, from DE 19931 385 A1. This document presents a method for manufacturing a motor or generator wedge. Also known is the disclosure in US 2012293037 A1. This disclosure relates to a coil fastening element for a rotating electric machine, which is a fastening element for securing a coil arranged in a slot of a stator core, and presents a rotating electric machine that uses the coil fastening element. WO 2023 / 152479 A1 also discloses a stator assembly for an electric machine for use in an aircraft.

[0007] -2 - Currently, winding areas in the winding slots are often overmolded. This makes it difficult to keep the spaces between the winding conductors open. Utilizing the winding slots as cooling channels for coolants such as oil is then challenging. Adhesive solutions are also frequently used to attach a cover slide to the stator. Such a cover slide can also be called a slot sealing wedge. While this type of adhesive may be beneficial for sealing the winding, it has other disadvantages. In particular, this solution is not suitable for mass production due to the requirements for technical cleanliness and the necessary process automation. It is also known to use separate sealing elements in the slot and / or at the axial stator ends, but this requires additional installation space and is difficult to assemble. In particular, the assembly tolerances are hard to control.

[0008] The purpose of the present invention is to mitigate or even completely eliminate the known disadvantages.

[0009] This problem is solved in a stator of the generic type according to the invention by providing, in order to ensure the sealing of the groove space, a sealing material that foams up when heated, and / or such a sealing material that foams up when heated, exclusively on at least one section of an edge region of the planar insulator, such as the groove paper, in order to achieve a fluid-tight configuration. In this way, air / creep distances are eliminated or at least improved. The edge region is understood to be the region that is located in relative proximity to a cut edge or outer edge of the planar insulator, i.e., within a few millimeters, in any case far from the center.

[0010] At the heart of the invention is an intumescent sealing material – exclusively in the edge areas of the planar insulator, i.e., the grooved paper – and / or on the cover slide. This leaves sufficient space for cooling fluid to flow around the winding conductors. There is complete design freedom with regard to the conductor geometry, cross-section, and shape. Overmolding is unnecessary for hairpin stators. The stator core no longer needs to be completely P241519

[0011] - 3 - can be overmolded. For wave-wound stators or stators with shaped coils, the slot / winding groove can remain open for radial winding assembly. Especially for such stator designs, the groove can now be efficiently sealed after radial winding assembly. This allows for a convenient connection between a slot insulation that is not overmolded and a stator end cap. In other words, the invention focuses on the use of a foaming material for the fluidic sealing of the assembly gaps and spaces between the insulation components: slot insulation and cover slide, and optionally at the axial end for sealing against the end cap.

[0012] It is no longer necessary to completely coat the entire slot insulation surface on both sides or one side. The cover slide is now coated either completely or partially on one side. The insulating material should only be coated on one side and in a small area, in particular only on one edge, two opposing edge areas, or all four edge areas. Due to the thermal activation, the space between the conductors and their edges remains sufficiently large to allow airflow. Leakage of the cooling medium at the slots and the winding head can be prevented. Such an invention is ideally suited for the field of electric motor development.

[0013] The foaming sealing material can also be used, in particular, to fasten the slot closure wedge to the stator or in the slots.

[0014] For the sake of simplicity, the descriptions in this document refer to radial flux machines, but their nature is not limited to them. Similar applications to axial flux machines are possible.

[0015] Advantageous stator designs include between 12 and 48 slots for the axial flux machine and between 36 and 120 slots for the radial flux machine. The active length of the stators can range from 30 to 500 mm. The respective DC link voltage for supplying the phases is preferably between 300 V and 1.2 kV. P241519

[0016] - 4 - The foaming material, in its coated initial state, has a layer thickness between 20 pm and 500 pm. The expansion factor, which describes the ratio of the layer thickness after thermal foaming to the initial layer thickness, is preferably between 1.5 and 15.

[0017] After thermal treatment, the foaming material forms a solid, material-bonded connection between the insulation elements of the stator, thereby establishing a media-tight connection with an internally porous structure.

[0018] Advantageous embodiments are claimed in the dependent claims and are explained in more detail below.

[0019] It is therefore advantageous if the cover slide is covered with the sealing material, preferably on one side facing the winding groove, at least at one of the edge regions, away from an interior area free of sealing material and far from the edge region, or if an entire side of the cover slide, preferably the side facing the winding groove, is covered with this sealing material. In one particular embodiment, the cover slide can thus be covered with the thermally foaming sealing material only at the edge region, whereas in another particular embodiment, the entire surface of the cover slide is completely covered. Depending on the requirements, a suitably prepared cover slide can then be used.

[0020] It is also advantageous if (only / at least) the two axially extending edge regions of the planar insulator, i.e., the grooved paper, are covered with the thermally foaming sealant, far from an interior area free of sealant and far from the edges. This results in efficient use of the sealant. A sealing effect is achieved only in critical areas. The result is an efficient design that produces a good sealing effect. P241519

[0021] - 5 - It has also proven effective if the thermally foaming sealant is present at least on one or both of the additional edge areas, far from an interior area free of sealant and far from the edge area. A circumferential application of the sealant, and / or axial alignment of the sealant, and / or a radially continuous design can then be achieved.

[0022] Another embodiment is also characterized in that the planar insulator is designed as grooved paper, which, for example, is inserted overlapping into the winding groove.

[0023] It has also proven effective to attach the sealing material to the grooved paper and / or the cover slide.

[0024] Another advantageous embodiment is characterized in that the sealing material is arranged at one or both axial ends of the winding groove for sealing against a connection assembly. The function of the connection assembly is to guide the media outside the active length of the stator. End caps, housing components, or gearbox covers are suitable as connection assemblies.

[0025] The invention also relates to an electric motor with a rotor which is arranged either inside and / or outside a stator of the type according to the invention for a radial flux machine.

[0026] Such an electric motor can advantageously also be characterized by the fact that the sealing material is applied as a layer of constant thickness. Alternatively or cumulatively, it is conceivable to coat one side with a first thickness and the other side with a different thickness. This is particularly useful when there are varying mounting gap dimensions / tolerances.

[0027] This invention offers particular advantages when connected to coolant-carrying elements in the winding head. P241519

[0028] - 6 - If the width of the sealing material is the same at all edge areas, precise mass production and more cost-effective manufacturing can be achieved.

[0029] Of course, the invention also relates to a method for sealing winding slots in a stator, namely using a foaming sealant / foaming sealing material, limited to an edge area in the case of a flat insulator / a slotted paper and / or in general / flat, or edge-limited, in the case of a cover slide / slot closure wedge.

[0030] The invention is explained in more detail below with the aid of a drawing. The drawing shows:

[0031] Fig. 1 shows a perspective view and a section of a stator according to the invention,

[0032] Fig. 2 shows a cross-section through a winding groove of the embodiment according to Fig. 1,

[0033] Fig. 3 shows another embodiment of a stator according to the invention,

[0034] Fig. 4 shows a section through the embodiment of the stator according to Fig. 3,

[0035] Fig. 5 shows another partially cutaway and perspective view of a stator according to the invention,

[0036] Fig. 6 shows a cross-section through a winding slot through the stator from Fig. 5,

[0037] Fig. 7 shows a special embodiment in a manner comparable to Figs. 2, 4 and 6, wherein foaming sealing material is applied only to the cover slide / groove locking wedge, namely either only radially inside, or only radially outside, or inside and outside (on both sides).

[0038] - 7 - sides of the cover slider / groove locking wedge, whereby full-surface mounting or only on both sides (in the circumferential direction) is conceivable,

[0039] Fig. 8 shows a further embodiment of the invention in a manner comparable to Figs. 2, 4, 6 and 7, wherein foaming sealing material is applied only to the flat insulator / insulating paper / grooved paper, either only on the inner side of the paper (the wire side), or only on the outer side of the paper (the sheet metal stack side) or on both sides (both sides of the paper), whereby a full-surface application or only on both sides and ends is conceivable.

[0040] Fig. 9 shows another embodiment in a manner comparable to Figs. 7 and 8, wherein only the insulating paper is pressed between the sheet metal stack and the foaming material / sealing material.

[0041] Fig. 10 shows a further embodiment in a manner comparable to Fig. 9, wherein foaming sealing material is attached to the groove closure part / the cover slide and is present at an overlap area of ​​the groove paper / insulating paper.

[0042] Fig. 11 shows a singular representation of a groove paper with applied foaming sealing material, wherein a partial or complete one-sided coating is intended and the foaming material is applied to the groove insulation paper in the vicinity of the cover slide, wherein the groove insulation paper is furthermore foldable into a U-shape,

[0043] Fig. 12 shows another representation of the nut insulation paper from Fig. 11 ,

[0044] Figs. 13 to 16 show two different embodiments of a cover slide prepared according to the invention (Figs. 13 and 14 on the one hand and Figs. 15 and P241519

[0045] - 8 - 16 on the other hand), wherein in Figs. 13 and 14 foaming sealing material is applied to the slot insulation paper in the immediate vicinity of the slot insulation paper and the cover slide is then mounted axially or radially into the stator with winding and slot insulation and subsequently foamed, wherein in the embodiment of Figs. 13 and 14 only a partial coating was carried out on the cover slide and in the embodiment of Figs. 15 and 16 completely,

[0046] Fig. 17 shows a further embodiment of a modified slot insulation paper according to the invention for enabling a fluid-tight connection to fluid-carrying elements in the winding head, and

[0047] Fig. 18 shows a further representation of the embodiment according to Fig. 17, wherein the joining of two half-shells is intended, both being provided with recesses in the groove area and the groove area closing the assembly air by foaming the groove paper.

[0048] The figures are purely schematic and serve only to illustrate the invention. Identical elements are identified by the same reference numerals. Features of the individual embodiments may be interchanged or substituted for one another.

[0049] Figure 1 shows a section of a stator 1 according to the invention. It is intended for use on an electric motor not shown in detail. It has a stator body 2. The stator body has a plurality of winding slots 3. Sections of a winding 4 formed by conductors are arranged in each winding slot. The winding 4 can be constructed from hairpins 5. Other winding configurations are also conceivable.

[0050] Cover slides 6 are located at the radially inner ends of the winding grooves 3. There is one cover slide 6 per winding groove 3. The cover slide 6 can also be referred to as groove closure P241519.

[0051] - 9 -wedge. Inside the winding groove 3, surrounding the winding(s) 4, a flat insulator 7 is arranged. This flat insulator 7 is designed as groove insulation paper 8.

[0052] According to the invention, foaming sealing material 9 is always present on the cover slides 6 and the groove insulation paper 8. This thermally foaming sealing material can be a foam or a film. In particular, a fluidic configuration is conceivable. This thermally foaming sealing material 9 is particularly well shown in Figs. 6 ff.

[0053] It should be noted that a combination of the embodiment of Fig. 7 and the embodiment according to Fig. 8 is possible. In the embodiment of Fig. 10, the groove insulation paper is inserted into the winding groove 3 with an overlap 10. As with the thermally foaming sealing material, which can only be applied to an edge area 11, for a cover slide, the design of the embodiment in Figs. 13 and 14 also allows the foaming sealing material to be applied only to an edge area of ​​the cover slide 6.

[0054] A complete surface coverage of one side of the cover slide 6 can be seen in the embodiment shown in Figures 15 and 16. If the thermally foaming sealing material 9 is used on all four edge areas of a groove insulation paper 8, the embodiment shown in Figures 17 and 18 is achieved. P241519

[0055] - 10 - List of reference symbols

[0056] 1 Stator

[0057] 2 Stator bodies

[0058] 3 Wicke I nut

[0059] 4 windings

[0060] 5 Hairpin

[0061] 6 Cover slider / groove locking wedge

[0062] 7-sided insulator

[0063] 8 Groove insulation paper / Groove paper

[0064] 9 Thermally foaming sealant 10 Overlap

[0065] 11 Edge area

Claims

P241519 DE - 11 - Patent claims 1. Stator (1 ) for an electric motor, comprising a stator body (2) having winding slots (3) for receiving a winding (4), with at least one cover slide (6) for closing at least one of the winding slots (3), wherein a planar insulator (7) is arranged in the winding slot (3) to space the winding (4) away from the stator body (2), characterized in that a sealing material (9) limited to this edge region (11) of the planar insulator (7) is present exclusively on at least one section of this edge region (11) and / or such a sealing material (9) which foams up when heated is present on the cover slide (6).

2. Stator (1 ) according to claim 1 , characterized in that the cover slide (6) is covered with the sealing material (9) at least on one of the edge regions (11), far from an interior region free of sealing material and far from the edge region, or an entire side of the cover slide (6) is covered with this sealing material (9).

3. Stator (1) according to one of claims 1 to 2, characterized in that the two axially extending edge regions (11) of the planar insulator (7) are covered with the sealing material (9) far from an interior area free of sealing material and far from the edge region.

4. Stator (1 ) according to claim 3, characterized in that the sealing material (9) is present at at least one further edge region (11 ) or both further edge regions (11 ) far from an interior region free of sealing material and far from the edge region.

5. Stator (1) according to one of claims 1 to 4, characterized in that the planar insulator (7) is designed as grooved paper (8). P241519 DE - 12 - 6. Stator (1) according to one of claims 1 to 5, characterized in that the sealing material (9) is attached to the grooved paper (8) and / or the cover slide (6).

7. Stator (1) according to one of claims 1 to 6, characterized in that the sealing material (9) is arranged at one axial end or both axial ends of the winding groove (3) for sealing against an end cap.

8. Stator (1) according to one of claims 1 to 7, characterized in that the sealing material (9) is applied as a layer of constant thickness.

9. Stator (1 ) according to one of claims 3 to 8, characterized in that the width of the sealing material (9) is the same at all edge regions (11).

10. Electric motor with a rotor arranged inside a stator (1) according to one of the preceding claims.

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