Stator with roof-shaped slot closure element for draining away oil, and electric machine

Abstract

The invention relates to a stator (1) for an electric machine (10), comprising: a main part (3) that has a plurality of slots (2) which are distributed in the circumferential direction and are open radially inwards; a coil assembly (4), a plurality of longitudinal portions (5) of the coil assembly (4) being arranged in each slot (2); and a plurality of slot closure elements (6), each of which closes a respective slot (2) towards a radial inner face (7) of the main part (3) radially within the longitudinal portions (5). Each slot closure element (6) has an inner contoured region (9) which runs in the axial direction and is inclined relative to the longitudinal axis (8). The invention additionally relates to an electric machine (10) comprising said stator (1).

Description

[0001] Stator with roof-shaped slot closure body for draining oil; and electrical machine

[0002] The invention relates to a stator for an electrical machine, comprising a base body having a plurality of circumferentially distributed slots (each of which opens radially inward), a coil arrangement, wherein a plurality of longitudinal sections of the coil arrangement are arranged in each slot, and a plurality of slot closure bodies, each of which closes a slot toward a radial inner side of the base body, radially within the longitudinal sections. Furthermore, the invention relates to an electrical machine having such a stator.

[0003] Generic electrical machines with stators featuring slot-locking bodies (also referred to as slot-locking wedges) are already well known. For example, reference is made to EP 2 568 576 A2, which discloses a cooling system integrated into a stator, in which slot wedges are used accordingly.

[0004] Depending on the cooling system implemented, it has been found that a significant amount of coolant (usually oil) can penetrate into the slots during operation. For example, oil enters the slots axially via the winding heads of the coil assembly. However, oil also enters the slots from the radial inside, particularly in the areas of the slot wedges, where it accumulates. Overall, this results in increased resistance to the rotation of a rotor relative to the stator.

[0005] The object of the present invention is therefore to further increase the efficiency of the electric machine while keeping the stator structure as simple as possible. This is achieved according to the invention in that each slot closure body has an inner contour region extending in the axial direction and inclined relative to a longitudinal axis (of the stator / base body).

[0006] This inner contour area thus exhibits an axial gradient, resulting in the oil accumulating in the respective groove within the slot seal body being automatically and specifically expelled axially from the gap area between the stator and rotor due to the subsequent oil flow during rotor rotation. This significantly reduces the efficiency loss at the rotor. Consequently, the electric machine can be operated more efficiently.

[0007] Further advantageous embodiments are claimed in the subclaims and explained in more detail below.

[0008] Accordingly, it is also advantageous if the inner contour area is roof-shaped, i.e., has a roof-shaped profile when viewed longitudinally. This makes the groove seal body easy to manufacture and, at the same time, prepares it for rapid oil drainage.

[0009] In this regard, it has also proven advantageous if the inner contour region has an axial center section that directly forms a radially innermost region of the slot closure body. Preferably, the center section provides a separation geometry in an axial center of the stator / base body, at which the oil is directed either to a first axial side or to a second axial side of the stator opposite the first axial side.

[0010] Furthermore, it is advantageous if the inner contour region has two beveled sections, each axially adjacent to the central section, with an inner diameter of the beveled sections (i.e., an inner diameter of the stator at the beveled sections directly forming the radial inner side) widening with increasing distance from the central section. If the beveled sections also have a continuous gradient, the flow is guided out of the gap area between the rotor and stator as quickly as possible.

[0011] In this regard, it is also advantageous if the inner contour area (in particular the central section) extends at least partially over the radial inside of the

[0012] base body protrudes inwards.

[0013] Furthermore, it is advantageous if the inner contour area is aligned axially centrally with the base body. This ensures the fastest possible drainage of excess oil.

[0014] Furthermore, the invention relates to an electric machine for a motor vehicle, having a stator according to the invention according to at least one of the previously described embodiments and a rotor arranged radially inside the stator.

[0015] The invention will now be explained in more detail below with reference to figures.

[0016] They show:

[0017] Fig. 1 is a longitudinal sectional view of a stator according to the invention according to a preferred embodiment along an axially extending groove, wherein the formation of a groove closure body arranged towards a radial inner side of this groove can be clearly seen,

[0018] Fig. 2 is a schematic cross-sectional view of an electrical machine comprising the stator according to Fig. 1 and a rotor, wherein the oil flows generated during operation are shown schematically, and

[0019] Fig. 3 is a detailed view of the area marked "III" in Fig. 1, illustrating an oil flow deflected at a central portion of the groove seal body during operation. The figures are merely schematic and serve solely to facilitate understanding of the invention. The same elements are provided with the same reference numerals.

[0020] First, in connection with Fig. 2, it should be noted that the stator 1 according to the invention, in its preferred embodiment, is implemented entirely in a ring shape and is used in an electric machine 10 (as a drive motor) of a motor vehicle. In addition to the stator 1, the electric machine 10 conventionally has a rotor 11 arranged radially within the stator 1, which is rotatably mounted relative to the stator 1.

[0021] The rotor 11 is rotatably mounted about a rotational axis that is aligned coaxially / concentrically with a longitudinal axis 8 of the stator 1. The directional information used herein refers to this longitudinal axis 8, whereby the axial / axial direction is understood to mean a direction along / parallel to the longitudinal axis 8, the radial / radial direction is understood to mean a direction perpendicular to the longitudinal axis 8, and the circumferential direction is understood to mean a direction along a circular line running concentrically around the longitudinal axis 8.

[0022] Fig. 2 shows the gap region 14 between the stator 1 and the rotor 11 in more detail. It can be seen that during operation of the electric machine 10, upon rotation of the rotor 11, a fluid flow / oil flow is generated which, due to the acting centrifugal force, is initially directed radially outward from the rotor 11, towards the stator 1. There, it finally encounters a radial inner side 7 of the stator 1 / a base body 3 of the stator 1 and is deflected axially, as can be seen in more detail in Fig. 3.

[0023] Returning to Fig. 1, it can be seen in principle that the stator 1 has a completely annular base body 3. The base body 3 is equipped with several grooves 2 distributed in the circumferential direction and opening radially inward. The base body 3 can, for example, be designed as a laminated core. Each groove 2 penetrates the base body 3 axially.

[0024] In each slot 2, several longitudinal sections 5 / coil sections of a coil arrangement 4 (such as a coil winding) of the stator 1, which can also be seen in Fig. 1, are inserted. The longitudinal sections 5 assigned to a slot 2 run essentially parallel to one another and are arranged stacked in the radial direction. The coil arrangement 4 forms a winding head 15 on both axial sides / ends of the stator 1.

[0025] Each groove 2 is closed inward in the radial direction by a groove closure body 6. This separately manufactured groove closure body 6 is particularly strip-shaped and has approximately the same length (axial extent) as the groove 2.

[0026] According to the invention, each slot closure body 6 is equipped with a roof-shaped inner contour region 9, which is inclined in sections with respect to the longitudinal axis 8. In conjunction with Fig. 3, it can be seen in this regard that the inner contour region 9 has a central section 12, which simultaneously forms the radially innermost region of the slot closure body 6. This central section 12 is positioned axially at the level of an axial center of the base body 3. From this central section 12, on each side, a beveled section 13a, 13b, which directly borders the central section 12, slopes downwards in the axial direction, so that an inner diameter of the slot closure body 6 / of the stator 1 in the circumferential region of the slot closure body 6 widens from the central section 12 in the region of these beveled sections 13a, 13b.

[0027] In principle, it is possible to extend the beveled sections 13a, 13b axially from the central section 12 to the axial ends of the grooves 2. Preferably, however, as implemented in the present invention, the beveled sections 13a, 13b are formed only in an axial partial section of the groove closure body 6. Directly adjacent to the respective beveled section 13a, 13b of the inner contour region 9 is a side region 16a, 16b having a continuous inner diameter (i.e., running parallel to the longitudinal axis 8).

[0028] In other words, the electrical machine 1 according to the invention (preferably with wave winding technology) uses slot closure wedges to prevent the winding / coil arrangement 4 from moving radially inward out of the stator slot (slot 2). Thus, relatively small slots / grooves are provided on an inner contour of the stator 1.

[0029] The shape of the slotted wedge is now designed so that when the oil radially impacts the slotted wedge, the rotational movement of the rotor 11 and the resulting centrifugal force create an axial flow direction of the oil from the air gap (gap area 14). This results in a roof-shaped cross-section of the slotted wedge over its axial length.

[0030] Fig. 1 shows the arrangement of the components in the stator in section along the stator axis / longitudinal axis 8. If oil is located in the air gap of the electric machine, it is displaced radially outwards by the rotational movement of the rotor 11 (Fig. 2).

[0031] When the radially displaced oil hits the slope (slope sections 13a, 13b) of the slot closure wedge, a predetermined axial flow direction of the oil is created (Fig. 3). This axial flow direction causes the oil to flow out of the air gap at both axial ends of the stator 1. The slope angle and the extension of the "roof shape" are optimized for the specific application.

[0032] stator

[0033] Nut

[0034] Basic body

[0035] Coil arrangement

[0036] Longitudinal section

[0037] Slot locking body

[0038] Inside of the base body

[0039] Longitudinal axis

[0040] inner contour area

[0041] machine

[0042] rotor

[0043] Middle section a first bevel section b second bevel section

[0044] gap area

[0045] Winding head a first side area b second side area

Claims

Patent claims 1 . Stator (1) for an electrical machine (10), with a base body (3) having a plurality of circumferentially distributed, radially inwardly open slots (2), with a coil arrangement (4), wherein in each slot (2) a plurality of longitudinal sections (5) of the coil arrangement (4) are arranged, and with a plurality of slot closure bodies (6), each of which closes a slot (2) towards a radial inner side (7) of the base body (3), radially inside the longitudinal sections (5), characterized in that each groove closure body (6) has an inner contour region (9) extending in the axial direction and inclined relative to a longitudinal axis (8).

2. Stator (1) according to claim 1, characterized in that the inner contour region (9) is roof-shaped.

3. Stator (1) according to claim 1 or 2, characterized in that the inner contour region (9) has an axial central section (12) which directly forms a radially innermost region of the slot closure body (6).

4. Stator (1) according to claim 3, characterized in that the inner contour region (9) has two beveled sections (13a, 13b) each axially adjacent to the central section (12), wherein an inner diameter of the beveled sections (13a, 13b) widens with increasing distance from the central section (12).

5. Stator (1) according to one of claims 1 to 4, characterized in that the inclined sections (13a, 13b) have a continuous gradient.

6. Stator (1) according to one of claims 1 to 5, characterized in that the inner contour region (9) projects inwards at least in sections beyond the radial inner side (7) of the base body (3).

7. Stator (1) according to one of claims 1 to 6, characterized in that the inner contour region (9) is aligned axially centrally to the base body (3).

8. Stator (1) according to one of claims 1 to 7, characterized in that side regions (16a, 16b) extending axially parallel to the longitudinal axis (8) adjoin the inner contour region (9).

9. Electrical machine (10) for a motor vehicle, with a stator (1) according to one of claims 1 to 7 and a rotor (11) arranged radially inside the stator (1).

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