Method for affixing the teeth of a stator to a casing

Abstract

Element (5) of an electric machine having a planar fixture surface (11) intended to be affixed by gluing to a planar fixture surface of another element of an electric machine, said element (5) being characterised in that it comprises at least two ribs (17) arranged to project from the planar fixture surface (11) and being, along the entire length thereof, the same height measured perpendicularly to said planar fixture surface (11)

Description

Description Title of the invention: Method for assembling the teeth of a stator to a casing

[0001] The invention relates to an architecture of stator teeth or of a casing in an axial flux rotating electrical machine, in particular of the permanent magnet type, with a view to their assembly.

[0002] As is known per se, rotating electrical machines comprise a stator, secured to a casing, and a rotor, secured to a shaft. The rotor may be secured to a driving and / or driven shaft and may belong to a rotating electrical machine in the form of an alternator or an electric motor. The casing is configured to rotate the rotor shaft, for example by means of bearings.

[0003] The rotor is provided with poles formed for example by permanent magnets while the stator has phase windings, typically made up of self-enclosed coils which are wound around teeth.

[0004] In axial flux electric machines, the stator and rotor are arranged so that the electromagnetic flux flows parallel to the rotor shaft. Most axial flux electric machines comprise several stators and / or rotors, each disc-shaped, with these elements separated, along the axial direction of the rotor shaft, by interstices called air gaps.

[0005] In certain configurations, two stators are arranged on either side of a rotor in the axial direction of the rotor shaft. Each stator may then consist solely of the teeth and their windings, which are fixed to the casing. The invention relates more particularly to this type of configuration.

[0006] The assembly of the stator teeth on the casing greatly influences the efficiency of the electrical machine. Indeed, this assembly makes it possible to control the air gap between the stator and the rotor. The air gap responds in particular to very precise distance constraints so that the magnetic field formed by the stator can drive the rotor in motor mode. In addition, the assembly must withstand the stresses undergone by the electrical machine (vibrations, temperature, etc.).

[0007] In addition, this assembly also influences the cooling of the component which is done, in certain configurations, by cooling circuits arranged on the external faces of the casings.

[0008] There are several solutions for assembling the stator teeth to the housing, the first being a screw assembly. However, this solution adds material and may require modifying the shape of the cooling circuit to be implemented.

[0009] A second solution is to glue the stator teeth to the casing. But using glue between two flat surfaces can cause several problematic. Indeed, if the quantity of glue is not uniform then the tooth will be poorly positioned on the housing, the air gap would then not be controlled. In addition, air bubbles can be created during assembly which would lead to a reduction in the bonding surface and therefore the strength of the tooth as well as a reduction in the efficiency of the cooling circuit since the heat exchange would be less optimal.

[0010] There is therefore a need for a tooth or casing architecture allowing it to be assembled by gluing to the casing while maintaining a constant air gap and avoiding the creation of air bubbles.

[0011] To this end, the present invention provides an electrical machine element which has a flat assembly face intended to be assembled by gluing to a flat assembly face of another element of an electrical machine. Said element comprises at least two ribs arranged projecting from its flat assembly face and having over their entire length the same height measured perpendicular to said flat assembly face.

[0012] Using the technique of bonding two electrical machine elements has the advantage of securing them without adding parts. In addition, the presence of ribs ensures a sufficient glue reserve while minimizing air bubbles to ensure complete and optimal bonding of the two elements. In addition, since the ribs are all of the same height, they allow for maintaining an identical spacing between the two assembled elements after bonding. The glue reserve is determined by the height of the ribs, which can preferably be from 0.2 millimeters to 0.8 millimeters.

[0013] The proposed solution is also easy to implement industrially, particularly when the ribs are made by punching.

[0014] Advantageously and in a non-limiting manner, the assembly face may be defined by a plurality of edges and the at least two ribs may extend from one edge to another edge of the assembly face.

[0015] An advantage is that the amount of glue in reserve can be controlled over a larger area since the at least two ribs extend from one edge of the assembly face to the other.

[0016] Advantageously and in a non-limiting manner, a rib may be arranged along one edge of the assembly face and the at least one other rib may be arranged along an opposite edge of the assembly face.

[0017] An advantage is also to control a larger surface for the quantity of glue which is framed by the at least two ribs and to facilitate the production of the element, in particular when it is a stator tooth.

[0018] Advantageously and in a non-limiting manner, the at least two ribs may be parallel to each other.

[0019] Advantageously and in a non-limiting manner, the at least two ribs may have a cross-section of identical shape over their entire length. length.

[0020] This can allow for an identical spread of the glue along the edges of the ribs. Note that the ribs can have a cross-section of identical shape but of variable dimensions along their length. This can allow, for example, to keep facing edges of the ribs parallel to each other. Alternatively, the ribs can have a cross-section of identical shape and dimensions along their entire length.

[0021] Generally speaking, it may be easier to make identical ribs.

[0022] Advantageously and in a non-limiting manner, each rib can have at least one of the following characteristics: - a quadrilateral-shaped cross-section, optionally trapezoidal-shaped, of which a first side is integral with the assembly face and of which at least the angles between a second side opposite the first side and lateral sides connecting them are rounded, - a cross-section symmetrical with respect to a median longitudinal plane perpendicular to the assembly face.

[0023] A quadrilateral-shaped cross-section with at least two or all of the corners rounded allows the glue present between the top of the rib and the assembly face of the other element to be evacuated to the sides of each rib when the two elements are pressurized to achieve bonding and thus ensures direct contact without a layer of glue between the top of the rib and the assembly face of the other electrical machine element.

[0024] This evacuation can be facilitated by a trapezoidal cross-section, the large base of which is integral with the assembly face and at least the angles between the small base and the lateral sides of which are rounded.

[0025] The symmetry of the cross-section, on the other hand, ensures an identical spread of the glue on each side of a rib.

[0026] Advantageously and in a non-limiting manner, the electrical machine element can be chosen from a stator tooth and a casing.

[0027] Another subject of the invention is a member of a rotating electrical machine, in particular an axial flux electrical machine, comprising a plurality of first elements each defining a stator tooth and a second element defining a casing. Each first element has a flat assembly face assembled by a layer of adhesive to a flat assembly face of the second element, and each of the first elements or the second element is an element as described above. At least two ribs then extend between the assembly face of each first element and the assembly face of the second element, and the layer of adhesive extends from an assembly face of each first element to the assembly face of the second element, each rib of the assembly face of an element being in direct contact with the face assembly of the opposite element.

[0028] Direct contact means that there is no glue between the rib and the assembly face of the facing element at their contact area.

[0029] Advantageously and in a non-limiting manner, each first element defining a stator tooth may be formed from a stack of sheets in a stacking direction, each sheet extending perpendicular to the assembly face of the casing. The at least two ribs may then advantageously extend parallel to a stacking direction of the sheets.

[0030] The invention also relates to a rotating electrical machine, in particular with axial flux, comprising a rotor comprising a rotor disc and a shaft, and two members as described previously, in which the rotor disc is integral in rotation with the shaft and the two members are mounted on either side of the rotor disc, the assembly face of the casing of each member being directed towards the rotor disc and the casing of each member being mounted on the shaft via bearings, the two casings being assembled to each other.

[0031] The invention may in particular relate to a motor vehicle equipped with the rotating electrical machine described above.

[0032] Other features and advantages of the invention will emerge from reading the description given below of several particular embodiments of the invention, given for informational purposes but not as a limitation, with reference to the appended drawings in which:

[0033] [Fig. 1] is a sectional view of an axial flux rotating electrical machine.

[0034] [Fig. 2] is a perspective view of a stator tooth according to one implementation of the invention.

[0035] [Fig. 3] is a perspective view of a stator tooth according to another implementation of the invention.

[0036] [Fig. 4] is a sectional view of a component of a rotating electrical machine according to one embodiment of the invention.

[0037] [Fig. 5] is a sectional view of a rib of a member of a rotating electrical machine according to an embodiment of the invention.

[0038] [Fig. 6] is a sectional view of a rib of a member of a rotating electrical machine according to another embodiment of the invention.

[0039] The invention relates to a rotating axial flux electric machine 1 in a motor vehicle.

[0040] With reference to Figure 1, the axial flux rotating electrical machine 1 comprises a rotor comprising a rotor disc 2 integral in rotation with an output shaft 3. The axis of rotation of this shaft 3 extends perpendicular to the rotor disc 2 and passes through the center of the latter. On each side of the rotor disc 2, the electrical machine 1 also comprises a member 4 comprising a plurality of first elements each defining a stator tooth 5 assembled to a second element defining a casing 6. This member 4 is separated from the disc of rotor 2 by a predetermined fixed distance called air gap 7.

[0041] The two members 4 are similar and have the same elements. For the sake of clarity, in Figure 1, the elements of only one of the members have been designated by references and in the remainder of the description, only one of the members 4 is described in detail, the structure of the other member 4 being identical or similar.

[0042] The metal casing 6 of the member 4 has an internal face 8 and an external face 9 opposite the internal face 8. These faces 8, 9 are the faces of a wall 14 of the casing. The casing can be made of any metal or alloy usually used to manufacture casings, such as aluminum. The casing 6 is also mounted on the shaft 3 via bearings 10.

[0043] The casing 6 has a half-shell shape thus covering the stator 5 and, in part, the rotor disk 2. It thus has a substantially flat wall 14 defining the internal 8 and external 9 faces and which extends parallel to the rotor disk 2, this wall 14 being provided with an external lateral wall 15 forming a face dedicated to coupling with the other casing and an internal lateral wall 16 comprising a bearing housing. The two cards of the members 4, located on either side of the rotor disk 2 are thus assembled to each other by their external lateral walls 15. The internal face 8, also called the flat assembly face 8, is thus defined (delimited) by a plurality of edges. This flat assembly face 8 of each casing is thus opposite a face of the rotor disc 2. The bearings 10 are received in the bearing housings of the internal side walls 16 of the members 4 and of the corresponding housings of the shaft 3.

[0044] The teeth 5 of the stator are here arranged so as to form a disc, or more precisely a ring, the center of which defines a cylindrical passage for the shaft 3. They are therefore placed radially with respect to this cylindrical passage, equidistant from the latter.

[0045] The teeth 5 are typically made from a stack of metal sheets 12, each sheet extending perpendicular to the inner face 8 of the casing 6 after assembly. The metal sheets 12 may be formed from any metal or alloy commonly used for stators, such as an alloy composed of iron and silicon. The teeth 5 of the stator are surrounded by metal wires 13, thus forming the coil. The metal wires 13 may be made from metals or alloys suitable for forming a coil, such as copper.

[0046] The teeth 5 of the stator also comprise a flat assembly face 11 defined (delimited) by a plurality of edges and intended to be secured by gluing to the internal face 8 of the casing 6, which is also a flat assembly face 8. In the example shown, the flat assembly face 11 has the shape of a quadrilateral, here a trapezium and is thus delimited by four edges 11a, 11b, 11c, 11d. The invention is however not limited to a shape of a flat face assembly. The latter depends in particular on the type of tooth used.

[0047] According to the invention, the teeth 5 of a member 4 are assembled to the associated casing 6 by glue.

[0048] The glue used is typically an epoxy or two-part glue.

[0049] To optimize the bonding of these elements, at least two ribs 17 are arranged projecting from one of the flat assembly faces 8, 11. These ribs 17 thus make it possible to separate the flat assembly faces, forming a free space which can be filled with glue. Preferably, the number of ribs is two but a greater number can be envisaged depending on the architecture of the element to be bonded.

[0050] These ribs 17 extend from the assembly face of the element to which they are secured to the assembly face of the other element. Thus, when the elements 5 and 6 of the member 4 are assembled, the tops of the ribs are in contact with an assembly face. The ribs 17 have the same height over their entire length measured perpendicular to the assembly face to which they are secured. They are thus arranged in such a way as to create one or more free spaces each forming a reserve 18 of glue of the same height as them. These reserves are formed between the ribs and / or between the ribs and the edges of the assembly face. The height of the ribs 17 can thus be chosen according to the quantity of glue to be applied for optimum assembly; it is typically chosen between 0.2 mm and 0.8 mm and preferably between 0.4 and 0.6 mm (limits included), for example 0.5 mm.The glue reserves 18 ensure total bonding of the tooth to the casing and reduce the risk of air bubbles being created because the space formed between the two assembly faces eliminates air bubbles when applying the glue. In addition, since the quantity of air bubbles likely to form is reduced, the heat exchange between the stator teeth 5 and the casing 6 is optimized.

[0051] The ribs 17 can be arranged either on each assembly face 11 of the plurality of first elements each defining a tooth 5, or on the assembly face 8 of the casing 6. Preferably, the ribs 17 are arranged on each of the teeth 5 of the stator as shown in FIGS. 2 to 4.

[0052] The ribs 17 are typically made of the same material as that used to form the tooth mating face or the housing mating face. Thus, they may, for example, be made of sheet metal. When made on a tooth, the ribs may be manufactured by punching.

[0053] Figure 2 shows a stator tooth 5 whose assembly face 11 has two projecting ribs 17, the tooth 5 being intended to be assembled to the assembly face 8 of the casing 6, as shown in Figure 4. In this embodiment, the ribs are parallel and extend from one edge 11c of the assembly face 11 to the opposite edge 11a, at a distance from the other edges, which makes it possible to define three glue reserves 18. These ribs 17 are identical and here have a section of identical shape and dimensions over their entire length.

[0054] However, the configuration of the ribs is not limited to this example. The ribs 17 may extend from one edge of one of the assembly faces 8, 11 to another edge of one of these assembly faces 8, 11. Thus, the ribs 17 do not necessarily extend between two opposite edges and may therefore connect two other edges, in particular contiguous edges.

[0055] With reference to Figure 3, the two ribs 17 are arranged along two opposite edges 11b, 11d of the assembly face. However, the arrangement of the ribs 17 is not limited to this example. Only one of the ribs can be arranged along one edge for example. In this example, the ribs 17 have a cross-section of identical shape over their entire length but whose dimensions increase progressively from one edge 11c of the assembly face to the other edge 11a. The ribs 17 are here identical but arranged symmetrically on either side of the tooth. In this embodiment, a single reserve of glue 18 is thus formed between the ribs, this reserve of glue here being of rectangular shape. The invention is of course not limited to a specific shape of the reserve of glue, the important thing being that the height of the reserve of glue is constant.

[0056] The ribs 17 preferably extend parallel to the stacking direction of the sheets as shown in Figures 2 and 3.

[0057] With reference to Figure 5, the cross-section of the ribs 17 may be rectangular in shape, one side 19 of which is integral with the assembly face 11. The ribs 17 also have rounded angles between the opposite side 20 to the side 19 and the lateral sides 21.

[0058] However, the cross-section of the ribs 17 is not limited to this shape. More generally, the cross-section may be in the form of a quadrilateral, a first side 19 of which is integral with the assembly face 11 and the angles between a second side 20 opposite the first side 19 and the lateral sides 21 of which are rounded.

[0059] Preferably, with reference to figure 6, the cross section of the ribs 17 may be trapezoidal in shape, a first side 19 of which, forming the large base, is integral with the assembly face 11. The ribs 17 also have rounded angles between a second side 20, forming the small base, opposite the large base 19 and the lateral sides 21.

[0060] The rounded corners allow the glue to be pushed out between the small base 20 and the opposite assembly face 8, thus allowing direct contact between these two surfaces. This makes it possible to control the bonding of the two assembly faces 8, 11 to each other and thus to control the distance of the air gap 7 between the teeth 5 of the stator and the rotor 2.

[0061] Finally, to control this distance and to allow an equal distribution of the glue between and / or around the ribs 17, these preferably have a symmetrical cross-section relative to a median longitudinal plane perpendicular to the assembly face 8, 11 with which they are integral.

[0062] Generally speaking, the teeth can be assembled to the casing by applying the glue to the assembly face that does not have the ribs. Then by joining the two assembly faces 8 and 11 together. During this step, the element with the ribs can be pressed for a long time until the glue is distributed in the reserves 18 and takes effect. By pressing on the element with the ribs, the glue present at the second side 20 of the rib will be expelled from this part towards the lateral edges of the ribs. In particular, rounded corners help to expel the glue, which will flow more efficiently and more quickly than if the corners are right-angled, which also helps to evacuate any air bubbles that may be present.

[0063] In the embodiments described with reference to the figures, the ribs are integral with the assembly face of the stator teeth. Alternatively, these ribs could be made projecting from the assembly face 8 of the casing, for example by a casting process or by machining. It will then be possible to provide the assembly face 8 of the casing with a plurality of groups of at least two ribs. This number of groups of ribs is then equal to the number of teeth to be fixed to the casing and the groups are positioned so as to correspond to the locations of the stator teeth to be fixed to the casing.

[0064] If the ribs are arranged on the assembly face 8 of the casing, it is not necessary for them to extend over the entire length of the casing. They can nevertheless advantageously extend from one edge to another of the assembly face 11 of the facing tooth 5.

[0065] Thus, whether the ribs are provided on the assembly face of each tooth or on the assembly face of the housing, at least two ribs extend between the assembly face of each stator tooth and the assembly face of the housing, thus allowing the spreading of a layer of adhesive between these assembly faces, the ribs (their top) being in close contact with an assembly face.

[0066] The invention has been described with reference to an axial flux rotating electrical machine having a rotor and two stators. It can nevertheless be applied to the assembly of stator teeth to a casing or to another tooth support element of an axial flux rotating electrical machine of different structure or even of a radial flux rotating electrical machine.

Claims

Claims

1. Element (5, 6) of an electrical machine (1) which has a flat assembly face (8, 11) intended to be assembled by gluing to a flat assembly face (11, 8) of another element (6, 5) of an electrical machine (1), said element (5, 6) being characterized in that it comprises at least two ribs arranged projecting from its flat assembly face (8, 14) and having over their entire length the same height measured perpendicular to said flat assembly face (8, 11).

2. Element (5, 6) of an electrical machine (1) according to claim 1, characterized in that the assembly face (8, 11) is defined by a plurality of edges and in that the at least two ribs (17) extend from one edge to another edge of the assembly face (8, 11).

3. Element (5, 6) of an electric machine (1) according to claim 1 or 2, characterized in that a rib (17) is arranged along one edge of the assembly face (8, 11) and in that the at least one other rib (17) is arranged along an opposite edge of the assembly face (8, H).

4. Element (5, 6) of an electrical machine (1) according to any one of claims 1 to 3, characterized in that the at least two ribs (17) are parallel to each other.

5. Element (5, 6) of an electrical machine (1) according to any one of claims 1 to 4, characterized in that the at least two ribs (17) have a cross-section of identical shape over their entire length.

6. Element (5, 6) of an electrical machine (1) according to any one of claims 1 to 5, characterized in that each rib (17) has at least one of the following characteristics: - a quadrilateral-shaped cross-section, optionally trapezoid-shaped, of which a first side (19) is integral with the assembly face (8, 11) and of which at least the angles between a second side (20) opposite the first side and lateral sides (21) connecting them are rounded, - a cross-section symmetrical with respect to a median longitudinal plane perpendicular to the assembly face (8, 11).

7. Element (5, 6) of an electric machine (1) according to any one of claims 1 to 6, characterized in that the electric machine element (1) is chosen from a stator tooth (5) and a casing (6).

8. Member (4) of a rotating electrical machine (1), in particular an axial flux electrical machine, comprising a plurality of first elements each defining a stator tooth (5) and a second element defining a casing (6), each first element having a flat assembly face (11) assembled by a layer of adhesive to a flat assembly face (8) of the second element, characterized in that each of the first elements or the second element is an element according to any one of claims 1 to 7, in that at least two ribs (17) extend between the assembly face (11) of each first element and the assembly face (8) of the second element, and in that the layer of adhesive extends from an assembly face (11) of each first element to the assembly face (8) of the second element, each rib (17) of the assembly face (8, 11) of an element being in direct contact with the assembly face (11, 8) of the opposite element.

9. Member (4) according to claim 8, in which each first element defining stator tooth (5) is formed from a stack of sheets (12) in a stacking direction, each sheet (12) extending perpendicular to the assembly face (8) of the casing, characterized in that the at least two ribs (17) extend parallel to a stacking direction of the sheets (12).

10. Rotating electrical machine (1), in particular with axial flux, comprising a rotor (2) comprising a rotor disc (2) and a shaft (3), and two members (4) according to claims 8 and 9, in which the rotor disc (2) is integral in rotation with the shaft (3) and the two members (4) are mounted on either side of the rotor disc (2), the assembly face (8) of the casing (6) of each member (4) being directed towards the rotor disc (2) and the casing (6) of each member (4) being mounted on the shaft (3) via bearings, the two casings (6) being assembled to each other.

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