Stator for axial flux electric machine

Abstract

The invention relates to a stator for an axial flux electric machine comprising: - a yoke (100), in the overall shape of a disc, centered on a longitudinal axis (A1), - teeth (200) distributed on a main face of the yoke around the longitudinal axis, each tooth comprising: ¤ a body (210) extending from the main face (103) of the yoke to a vertex (211) of the body, along the longitudinal axis, said body having a central edge (213) facing the longitudinal axis and a peripheral edge (214) opposite the central edge, ¤ a pair of lateral edges (220) bordering the vertex of the body, each lateral edge extending from the central edge of the body towards the peripheral edge of the body in a lateral direction (A3), characterized in that at least one of the lateral edges: - has at least one dimension (E, L), measured along a direction orthogonal to the lateral direction,which varies along the lateral direction and is greater near the central edge of the body than near the peripheral edge of the body, and / or - extends at a distance from the peripheral edge of the body. Figure for the abbreviation: Fig. 2,

Description

Title of the invention: Stator for axial flux electric machine Technical field of the invention

[0001] The present invention relates generally to electrical machines.

[0002] It relates more particularly to a stator for an axial flux electric machine.

[0003] It also relates to a method of assembling such a stator.

[0004] The invention finds a particularly advantageous application in electric motors for electric or hybrid motor vehicles. State of the art

[0005] A conventional axial flux electric machine stator comprises a yoke in the overall shape of a disc centered on a longitudinal axis and teeth distributed on a main face of the yoke around the longitudinal axis, each tooth carrying a winding of conductive wire. Under the effect of electric currents, the coils generate magnetic fields allowing the stator to set a rotor in motion.

[0006] The teeth generally have a body and a pair of magnetically conductive lateral flanges bordering a top of the body. The lateral flanges extend generally radially from the center towards the periphery of the stator. The two lateral flanges of a tooth each extend opposite a flange of an adjacent tooth, which makes it possible to minimize the circulation of the magnetic flux between the teeth and to improve it in the direction of the rotor.

[0007] The applicant has found that, when the stator is in operation, that is to say supplied with current, the density of the magnetic fluxes flowing through it is very inhomogeneous. Certain parts, such as the parts of the teeth close to the longitudinal axis and the peripheral part of the yoke, are traversed by high density fluxes, which generates significant iron losses (losses including eddy current and hysteresis losses). These significant iron losses limit the efficiency and power of an electrical machine comprising the stator. In addition, these high density fluxes also lead to an increase in the current injected into the coils and therefore to significant copper losses (Joule effect losses) in the latter. Conversely, other parts, such as the parts of the teeth close to the periphery of the stator, are traversed by low density fluxes. Presentation of the invention

[0008] In this context, the present invention provides a stator for an axial flux electric machine comprising: - a cylinder head, in the overall shape of a disc, centered on a longitudinal axis, - teeth distributed on a main face of the cylinder head around the longitudinal axis, each tooth comprising: H a body rising from the main face of the cylinder head to a top of the body, along the longitudinal axis, said body having a central edge facing the longitudinal axis and a peripheral edge opposite the central edge, H a pair of side flanges bordering the top of the body, each side flange extending from the central edge of the body towards the peripheral edge of the body in a lateral direction, at least one of the side flanges: - having at least one dimension, measured in a direction orthogonal to the lateral direction, which varies along the lateral direction and which is greater near the central edge of the body than near the peripheral edge of the body, and / or - extending away from the peripheral edge of the body.

[0009] Thanks to the invention, the lateral edges have more material on the side of the central edges than on the side of the peripheral edges of the bodies, that is to say more material in the central zone of the stator. Thus, the edges have more material where the magnetic flux is greater, which therefore makes it possible to reduce the density of the magnetic flux circulating there, and consequently to limit iron losses.

[0010] In a complementary manner, the stator according to the invention also makes it possible, compared to a conventional stator, to save on the manufacturing material of the flanges at the peripheral edges. Indeed, since the density of the magnetic flux circulating there is low, refining and / or shortening the flanges near the peripheral edges does not increase, or only very little, the iron losses.

[0011] It therefore appears that, compared to a conventional stator in which the lateral edges have a constant profile, the stator according to the invention makes it possible to better distribute the magnetically conductive material forming the lateral edges by providing more material in the areas where the circulation of the magnetic flux is high and / or by saving this material in an area where the circulation of the magnetic flux is low. Thus, the density of the magnetic flux passing through the edges is much more homogeneous than in a conventional stator, which makes it possible to limit iron losses and to increase the efficiency or power of the stator.

[0012] Other advantageous and non-limiting characteristics of the stator according to the invention, taken individually or in all technically possible combinations, are the following: - said dimension varies along the lateral direction of said lateral rim such that said dimension has: a first value in an area of ​​said lateral rim close to the central edge of the body, and a second value in an area of ​​said lateral rim close to the peripheral edge of the body, the second value being strictly less than the first value; - said lateral edge extends at a distance, measured along the lateral direction, from the peripheral edge of the body which is between 10% and 50% of a length of an edge of the top of the body measured between the central edge and the peripheral edge of the body; - said lateral edge is made up of several elements distinct from each other, said dimension being greater at the level of the element closest to the central edge of the body than at the level of the element closest to the peripheral edge of the body; - the lateral direction is parallel or orthogonal to the longitudinal axis; - the dimension decreases continuously along the lateral direction; - the cylinder head has, vertically above said lateral edge, a thickness, measured parallel to the longitudinal axis, which varies along the lateral direction such that the thickness is greater in an area of ​​the cylinder head away from the longitudinal axis than in an area of ​​the cylinder head close to the longitudinal axis.

[0013] The invention also proposes an axial flux electrical machine comprising at least one stator as described above and at least one rotor arranged to be driven in rotation by the at least one stator.

[0014] The invention also proposes a method of assembling a stator as described above, each tooth comprising an envelope made of insulating materials interposed between the body of said tooth and a winding carried by said tooth, the method comprising a step of integrating said lateral rim within the envelope.

[0015] Optionally and advantageously: - the step of integrating said lateral edge within the envelope is carried out prior to positioning the envelope on the body; - the integration step comprises an insertion of said lateral edge between the envelope and the body in the lateral direction, after positioning the envelope on the body; - the casing and the body delimit a hollow relief of a shape complementary to the shape of said lateral edge such that once inserted, said lateral edge blocks any movement of the casing parallel to the longitudinal axis.

[0016] Of course, the various features, variants and embodiments of the invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive. Detailed description of the invention

[0017] The description which follows with reference to the appended drawings, given as non-limiting examples, will make it clear what the invention consists of and how it can be implemented.

[0018] In the attached drawings:

[0019] [Fig-1] is a schematic view in perceptive of the cylinder head and the teeth forming a stator according to the invention;

[0020] [Fig.2] is a schematic exploded perspective view of an angular sector of a first embodiment of a stator according to the invention;

[0021] [Fig.3] is a schematic exploded perspective view of an angular sector according to another variant of the first embodiment of a stator according to the invention;

[0022] [Fig.4] is a schematic exploded perspective view of an angular sector of a second embodiment of a stator according to the invention;

[0023] [Fig.5] is a schematic exploded perspective view of an angular sector according to yet another variant of the first embodiment of a stator according to the invention;

[0024] [Fig.6] is a set of schematic views describing an assembly method according to the invention, each step of the assembly method is illustrated by a front view (from the center of the stator) in column F and a side view (from an adjacent sector) in column C of an angular sector of the stator according to the invention;

[0025] In [Fig.l], a stator 1 according to the invention is partially shown. In particular, the following parts of the stator 1 can be distinguished: - a 100 cylinder head; and - a plurality of teeth 200.

[0026] This stator 1 is intended to be assembled in an axial flux electric machine, in this case a motor for propelling an electric vehicle. Such an electric machine comprises at least one rotor and at least one stator. In practice, it may comprise a rotor located between two stators, generally identical.

[0027] The rotor generally comprises an annular-shaped body which houses a plurality of magnetic pole elements having the same function as permanent magnets. Magnetic pole elements consist of magnetic blocks arranged side by side so as to form a sort of ring in the rotor. These magnetic pole elements preferably consist of small assembled permanent magnets. The magnetic pole elements can also be manufactured by mixing a metal powder in a plastic matrix. Alternatively, the rotor can be a reluctance or induction rotor, in which case it is devoid of permanent magnets.

[0028] In Figures 2 to 6, for simplicity, only one angular sector 10 of the stator 1 has been shown. Here, all the angular sectors 10 forming the stator 1 are identical and each angular sector 10 comprises only one of the teeth 200.

[0029] Each tooth 200 here carries a winding 300 of conductive wire, as shown for example in [Fig.2]. When the windings 300 are supplied with electric current, they make it possible to generate a magnetic field so as to rotate the rotor.

[0030] As shown in [Fig.l], the yoke 100 essentially has the shape of a disc centered on a longitudinal axis A1. However, it has a circular central opening which is delimited by a central face 101 of the yoke 100. The yoke 100 also has a peripheral face 102 which here corresponds to its outer periphery, that is to say here its face remote from the longitudinal axis A1. Thus, the yoke 100 here has the shape of a flattened ring whose thickness is less than the diameter. The yoke 100 also comprises an upper face 103 facing the rotor, and a lower face 104, opposite the upper face 101. Here, the lower face 104 is orthogonal to the longitudinal axis AL. The upper face 101 can also be orthogonal to the longitudinal axis Al (as shown in [Fig.l]) or, as detailed below, inclined relative to the longitudinal axis Al (as shown in [Fig.6]).

[0031] As a variant of the polygonal shape shown in [Fig.l], the cylinder head may have a circular shape, i.e. with cylindrical central and peripheral faces. The same applies to the teeth.

[0032] In the description, the terms “central” and “peripheral” are defined with reference to the shape of the yoke 100 relative to the longitudinal axis A1 and in a plane orthogonal to this axis. The terms “central” and “peripheral” will respectively designate faces or portions of elements facing the longitudinal axis A1 (or opposite this axis) and, by contrast, faces or portions facing in the opposite direction. Thus, a “center” and a “periphery” of the stator 1 will also be defined as disjointed parts radially spaced from one another and which respectively comprise the central face 101 and the peripheral face 102 of the yoke.

[0033] As shown in [Fig. 2], each tooth 200 more specifically comprises a body 210 rising from the upper face 103 of the yoke to a vertex 211 of the body 210. Each body 210 rises along the longitudinal axis A1, i.e. parallel to the longitudinal axis A1 and opposite the lower face 104. Each body 210 thus ends with a flat end face 212 opposite the lower face 104 of the yoke 100. Each body 210 generally has the shape of a right prism, of trapezoidal section (here isosceles trapezoidal) in a plane orthogonal to the longitudinal axis A1. Each body 210 here has a plane of radial symmetry, i.e. a plane containing a radial direction A2, as shown in [Fig.l], and the longitudinal axis AL A radial direction here means a direction perpendicular to the longitudinal axis AL Alternatively, the bodies of the teeth can have other shapes, for example they can be beveled or not have a plane of radial symmetry.

[0034] Each body 210 has a central edge 213 facing the longitudinal axis A1 and a peripheral edge 214 opposite the central edge 213. Here, the central edges 213 rise from the central face 101 of the yoke 100. Conversely, the edges peripherals 214 rise from the peripheral face 102 of the cylinder head 100.

[0035] The yoke 100 and the bodies 210 of the teeth 200 are here produced by cutting, for example by punching, and stacking the metal sheets. Preferably, the yoke 100 and the bodies 210 of the teeth 200 are manufactured in one piece by winding around the longitudinal axis A1 a single metal sheet, for example made of non-oriented grain magnetic steel, cut into notches. The metal sheet can also be made of oriented grain magnetic steel. Alternatively, the yoke and the bodies of the teeth can be made of soft magnetic material (as described below for the lateral edges).

[0036] Each tooth 200 also comprises a pair of lateral edges 220 bordering the apex 211 of the body 210 of the tooth 200. Here, for each tooth 200, each of the two lateral edges 220 extends from the central edge 213 of the body 210 towards the peripheral edge 214 of the body 210 in a lateral direction A3. The lateral edges 220 thus extend substantially radially from the center to the periphery of the stator 1.

[0037] Here, the lateral direction A3 of each lateral rim 220 is parallel to a radial direction A2 passing through the rim 220, that is to say intersecting at least one point of the rim 220. As shown in [Fig.2], each of the two lateral rims 220 has its own lateral direction A3. It is noted that each lateral rim 220 can share its lateral direction A3 with the diametrically opposite lateral rim 220 facing it with respect to the longitudinal axis AL. Here, the lateral direction A3 of each lateral rim 220 is parallel to the edge of the body 200 facing it.

[0038] As illustrated in [Fig.l], the lateral edges 220 of each tooth 200 extend opposite the lateral edges 220 of the adjacent teeth 200. Two teeth 200 are here adjacent when they are located side by side along the circumference of the stator 1.

[0039] The lateral edges 220 are here made of a magnetically conductive material in order to improve the circulation of the magnetic flux between the teeth 200 and the rotor. Here, the lateral edges 220 comprise at least one ferromagnetic material. Preferably, the edges 220 are also made of an electrically insulating material in order to reduce eddy current losses. For example, the lateral edges 220 may be formed of a plastic matrix comprising ferromagnetic metal particles, for example steel. Insulated from each other by the plastic material, the metal particles thus conduct the magnetic flux but do not conduct the currents that can circulate in the teeth. As a further example, the lateral edges 220 may be formed of partially oxidized metals.Thus, in general, the side edges 220 are manufactured so as to efficiently conduct magnetic fluxes but very weakly conduct electric fluxes. Alternatively, the side edges can be manufactured by a stack. of metal sheets.

[0040] Each tooth 200 further comprises an envelope 230 made of non-magnetic and electrically insulating material, for example plastic, resin or adhesive material. Each envelope 230 matches the shape of the body 210 of its tooth 200, in particular over the height of the body 210, as shown in [Fig. 2]. Here, each envelope 230 thus has a generally hollow cylindrical shape and comprising two opposite openings, one opening onto the top 211 of the body 210 and the other onto the yoke 100. Here, as shown in [Fig. 2], the envelope 230 also forms flat rings bordering each of the opposite openings. These rings are thus located on either side of the winding 300 along the longitudinal axis A1.

[0041] Each envelope 230 partially or completely surrounds the lateral edges 220 of its tooth 200. Preferably, as shown in [Fig.2], the envelopes 230 are in particular interposed between the lateral edges 220 and the bodies 210 of the teeth 200 so as to separate the latter, which limits the circulation of currents between the two, thus reducing eddy current losses. Preferably, the envelopes 230 are also interposed between the lateral edges 220 of adjacent teeth 200, which also makes it possible to electrically insulate the lateral edges 220. The envelopes 230 of adjacent teeth 200 may be in contact with each other, above the windings 300, at the level of the tops 211 of the teeth 200, and below the windings 300, at the level of the yoke 100.

[0042] One of the lateral edges 220 of one of the teeth 200, which are then subsequently called the lateral edge 220 and the tooth 200, is now described in detail. Here, the other lateral edge 220 of the tooth 200 has a symmetrical shape (as seen in FIGS. 2 to 6). Here, the pairs of lateral edges 220 of the other teeth 200 are identical. However, their shape might not be identical.

[0043] The objective of the invention is to increase the volume of the lateral rim 220 at the center of the stator 1 because the density of the magnetic fluxes is high there, and, conversely, to reduce the volume of the lateral rim 220 at the periphery of the stator 1 because the density of the magnetic fluxes is low there.

[0044] A first way of obtaining this peripheral reduction of the lateral edge 220 is to refine it, according to one or more dimensions orthogonal to the lateral direction A3, going from the central edge 213 towards the peripheral edge 214 of the body 210 of the tooth 200.

[0045] Thus, in a first embodiment of the stator 1 shown in [Fig.2] and 3, at least one dimension of the lateral rim 220, measured in a direction orthogonal to the lateral direction, which varies along the lateral direction A3 and which is greater near the central edge 213 of the body 210 than near the peripheral edge 214 of the body 210. In other words, this dimension of the lateral rim 220 decreases with the distance from the central edge 213.

[0046] Thus, there is a central zone of the lateral rim 220, close to the central edge 213 of the body 210 in which the dimension has a first value, and a peripheral zone of the lateral rim 220, close to the peripheral edge 214 of the body 210 in which the dimension has a second value, such that the second value is strictly less than the first value. Here, the central zone and the peripheral zone are defined as parts which are disjointed and spaced apart from each other in the lateral direction A3, i.e. here radially disjointed and spaced apart.

[0047] In the example shown in [Fig. 2], the lateral edge 220 has a rectangular section S defining two dimensions: a width L, measured in a direction orthogonal to the lateral direction A3 and to the longitudinal axis A2 (i.e. here a substantially orthoradial direction); and a thickness E, measured in a direction orthogonal to the lateral direction A3 and parallel to the longitudinal axis A1. As can be seen in [Fig. 2], the thickness E and the width L of the lateral edge 220 decrease along the lateral direction A3 in the direction of the peripheral edge 214, i.e. in the direction of the periphery of the stator 1.

[0048] As shown in [Fig. 2], the thickness E and the width L decrease continuously. They thus decrease over the entire length of the lateral edge 220, that is to say along its entire length in the lateral direction A3. The thickness E and the width L decrease more specifically in a regular manner. As shown in [Fig. 2], they decrease linearly as a function of the distance from the longitudinal axis A1. Alternatively, the thickness and / or the width of the lateral edge could decrease in another way, for example according to a curve defined by the square root function.

[0049] Of course, in a variant of this first embodiment, the lateral edge 220 may have only one dimension which decreases along the lateral direction A3, for example only its thickness E or only its width L.

[0050] The lateral rim 220 may also have more than two decreasing dimensions along the lateral direction A3. Such a lateral rim 220 is for example shown in [Fig. 3]. As shown in [Fig. 3], it has here a section S of more complex shape than in [Fig. 2] since it has a curved face 223. In this example, the lateral rim 220 has more than two decreasing dimensions in the sense that it is possible to define more than two directions orthogonal to the lateral direction A3 (for example passing through the curved face 223) according to which the size of the rim decreases towards the periphery of the stator 1. Three of these dimensions, referenced D1, D2, D3 are shown in [Fig. 3].

[0051] In this first embodiment, the lateral rim 220 extends here from the edge central edge 213 of the body 210 to the peripheral edge 214 of the body 210, in the sense that they have two end faces 221, 222 which are respectively flush with the central edge 213 and the peripheral edge 214 of the body 210.

[0052] A second way of achieving this peripheral reduction of the lateral rim 220 is to shorten it so that it does not extend to the peripheral edge 214 of the body 210.

[0053] Thus, in a second embodiment shown in [Fig.4], the lateral edge 220 extends at a distance from the peripheral edge 214 of the body 213. In other words, the lateral edge 220 is shorter than the body 210 of the tooth 200 in the lateral direction A3. Thus, there is, along the lateral direction A3, a portion of the tooth 200, here a peripheral portion, devoid of a lateral edge.

[0054] The lateral edge 200 extends for example at a distance from the peripheral edge of the body which is between 10% and 50% of a length of an edge of the upper face 212 of the body 210 between the central edge 213 and the peripheral edge 214 of the body 210. This distance is preferably greater than 20%.

[0055] As shown in [Fig. 4], the side flange 220 is positioned set back from the peripheral edge 214 of the body 210 in the direction of the central edge 213 of the body 210. The side flange 220 has a central end face 221 facing the longitudinal axis A1 and a peripheral end face 222 opposite the central end face 221 along the lateral direction A3. The side flange 220 extends away from the peripheral edge 214 of the body 213 in the direction where the peripheral end face 222 is located, along the lateral direction A3, between the central edge 213 and the peripheral edge 214 of the body 210.

[0056] In the example of this second embodiment shown in [Fig.4], the lateral edge 220 has a rectangular section S which is constant along the lateral direction A3. The lateral edge 220 thus has a parallelepiped shape. The reduction in material is simply obtained by shortening the lateral edge.

[0057] Of course, these two embodiments can be combined with each other. Thus, the lateral rim 220 can have at least one decreasing dimension (for example its thickness E) in the direction of the peripheral edge 214 of the body 210 while extending at a distance from the peripheral edge 214 of the body 210, that is to say set back from the latter.

[0058] Until now, the stator 1 illustrated in FIGS. 2 to 4 presented the lateral edge 220 as a single piece, i.e. made from a single piece.

[0059] However, whatever the embodiment, it is possible to segment the lateral edge 220 into several elements 225 distinct from each other. The reduction of material at the periphery of the stator 1 can then be obtained by reducing the size of the element(s) 225 closest to the peripheral edge 214 of the body 210 in comparison with the element(s) 225 closest to the central edge 213 of the body 210.

[0060] Thus, the lateral rim 220 can therefore be formed from several elements 225 so that at least one dimension of the lateral rim 220, measured in a direction orthogonal to the lateral direction A3, has a third value for an element 225 which is close to the central edge 213 of the body 210 and a fourth value for another element which is close to the peripheral edge 214 of the body 210, the fourth value being strictly less than the third value.

[0061] In the example shown in [Fig.5], the lateral edge 220 is made up of three distinct and disjointed elements 225. Each of the elements 225 has a parallelepiped shape. The lateral edge 220 here has a decreasing thickness E, in steps, along the lateral direction A3 towards the periphery of the stator 1. Thus, the element 225 closest to the central edge 213 of the body 210 (which is here flush with the central edge 213) has the greatest thickness E of the lateral edge 220 while the element 225 closest to the peripheral edge 214 of the body 210 (which is here flush with the peripheral edge 214) has the smallest thickness E of the lateral edge 220. The element 225 located between these two latter has an intermediate thickness.

[0062] Of course, the thickness (and other dimensions as well) of each element 225 could decrease continuously with the distance from the longitudinal axis AL

[0063] Here, when the thickness of the lateral edge 220 decreases towards the periphery of the stator 1, the yoke 100 is preferably thicker at its peripheral face 102 than at its central face 101. As shown in [Fig.6] (side view of step E3), this variation in thickness of the yoke 100 combines advantageously with the variation (in the opposite direction) in the thickness of the lateral edge 220. Indeed, the winding 300, which is generally sandwiched between the yoke 100 and the lateral edge 220, can then have a constant thickness which allows for a regular and therefore simple winding of the conductive wire. As detailed below, once in place, the winding 300 then has an inclination (corresponding to the variation in thickness of the rim and the yoke) relative to a radial direction A2 of the tooth 200 which is perpendicular to the longitudinal axis AL

[0064] The dimension of the yoke 100 called thickness is more particularly that which is parallel to the longitudinal axis A1 (as for the lateral edge). For any point on the upper face 101, the thickness of the yoke 100 is therefore here equal to the distance between the upper face 101 and the lower face 102 measured parallel to the longitudinal axis A1. The thickness of the yoke 100 is for example measured between each pair of teeth 200.

[0065] The thickness of the cylinder head 100 is here referenced C in [Fig.6] (step E1). As clearly appears in this [Fig.6], the thickness C of the cylinder head 100 varies along a radial direction A2 such that the thickness C is greater in an area of ​​the cylinder head 100 spaced from the longitudinal axis Al than in an area of ​​the cylinder head 100 close to the longitudinal axis Al.

[0066] In order to assemble the stator 1, it may be provided to place the lateral edge 220 within the casing 230 before or after the positioning of the casing 230 on the body 210 of the tooth 200. Thus, in a first embodiment of the method for assembling the stator 1, the lateral edge 220 is inserted within the casing 230 before the positioning of the casing 230 on the body 210 of the tooth 200. In a second embodiment of the stator 1, the lateral edge 220 is inserted within the casing 230 after the positioning of the casing 230 on the body 210 of the tooth 200. Here, all the lateral edges 220 of the stator 1 are put in place in the same way.

[0067] The assembly method here is part of a broader method for manufacturing the stator 1. The manufacturing method notably comprises the manufacturing of the yoke 100 and the bodies 210 of the teeth 200 by winding and punching a metal sheet. It also comprises the manufacturing of the lateral edge 220, for example by compressing a powder of oxidized ferromagnetic grains or by mixing ferromagnetic grains in a matrix of plastic material. In the context of the second embodiment of the assembly method, the method for manufacturing the stator 1 notably comprises a manufacturing step, for example by molding, of the different parts of the casing 230.

[0068] The first embodiment is described with reference to [Fig.2]. This first embodiment comprises a step of integrating the lateral rim 220 within the envelope 230.

[0069] The lateral rim 220 is for example integrated into the casing 230 by overmolding the casing 230 around the lateral rim 220. In practice, the two lateral rims 220 of each tooth 200 are then integrated into the casing 230 by overmolding.

[0070] The lateral edge 220 can also be fixed to the casing 230 which is then prefabricated. A hollow relief corresponding to the shape of the lateral edge 220 is then provided in the casing 230 (in practice two hollow reliefs for the two edges). During the integration step, the lateral edge 220 is then fixed in the casing 230, for example by glue or by mechanical means such as clips.

[0071] In this first embodiment, the method then comprises a step of winding the coil 300 around the casing 230. Here, it is provided that the loops of conductive wire constituting the coil 300 cross at the central edge 213 of the body 210.

[0072] The assembly method finally comprises a step of positioning the envelope 230 around the body 210. The envelope 230 is here slid around the body 210 by a translational movement parallel to the longitudinal axis Al until it is in contact with the upper face 101 of the cylinder head 100.

[0073] The second embodiment of the assembly method is described with reference to [Fig.6]. The idea of ​​this second embodiment is to insert the lateral rim 220 into a hollow relief provided in the casing 230 and the tooth 200.

[0074] As shown in [Fig.6], the casing 230 here comprises a first part 231 designed to match the shape of the body 210 of the tooth 200, parallel to the longitudinal axis A1, and of a part of the upper face 101 of the yoke 100.

[0075] In this second embodiment, the assembly method thus comprises a first step E1 of positioning the first part 231 of the casing 230 around the body 210. The first part 231 of the casing 230 is here slid around the body 210 by a translational movement parallel to the longitudinal axis A1 until it is in contact with the upper face 101 of the yoke 100.

[0076] The casing 230 also comprises a second part 232 of a shape complementary to the first part 231. Here, the combination of the first part 231 and the second part 232 of the casing 230 makes it possible to form the entire casing 230 (an casing of a shape similar to that of the first embodiment of the assembly method is thus obtained). The second part 232 of the casing 230 is more specifically provided to carry the winding 300.

[0077] The assembly method thus comprises a second step E2 of winding the coil 300 around the second part of the casing 230 and of positioning the second part of the casing 230 around the first part 231 of the casing 230. The second part 232 of the casing 230 is here slid around the first part 231 of the casing 230 by a translational movement parallel to the longitudinal axis A1 (front view of step E2 in [Fig.6]).

[0078] The assembly method then comprises a third step E3 of inserting the lateral rim 220 between the casing 230 and the body 210 by a translation in the lateral direction A3, that is to say here in a radial direction A2. The lateral rim 220 is more specifically inserted into a hollow relief 240 formed in the second part of the casing 232 and the top 211 of the body 210, as visible in [Fig. 6] (front view of step E2). This hollow relief 240 thus also extends lengthwise in the lateral direction A3 and is open towards the end face 211 of the body 210 of the tooth 210. The hollow relief 240 comprises a peripheral wall provided in the second part 232 of the casing 230 against which the lateral rim 220 abuts at the end of its insertion.

[0079] Advantageously, as shown in [Fig.6] (front views of steps E2 and E3), the relief in those 240 and the lateral edge 220 are of complementary shape so that once inserted the lateral edge 220 blocks a movement of the envelope 230 pa connection to the longitudinal axis A1. In other words, the lateral edge 220 blocks a movement of the envelope 230 contrary to its positioning movement around the body 210 of the tooth 200. This is achieved here by an inclined face of the top 211 of the tooth 200 and an inclined face of the lateral edge 220.

[0080] In a complementary manner, the lateral edge 220 is here integral with one of the two lateral edges 220 of the adjacent tooth 200. These two lateral edges 220 are for example manufactured in a single piece. Although this slightly degrades the electromagnetic performance of the lateral edges 220 (because they are in contact with each other), this makes it possible to lock by complementary shape the two lateral edges 220 in the hollow reliefs provided in the two adjacent teeth 200 during their radial insertion. Indeed, it is for example possible to provide a dovetail fitting, as partially shown in [Fig.6] (front view of step E3). The lateral edges 220 then form a tenon when the hollow reliefs form a mortise. The lateral edges 220 then have a single degree of freedom relative to the hollow reliefs, namely a translation in a radial direction A2.

[0081] As clearly shown in the side view of step E2 in [Fig.6], at the end of the second step E2, a portion of the second part 232 of the envelope 230 located opposite the central edge 213 of the body 210 is slightly raised relative to the yoke 100. Thus, the loops of conductive wire constituting the winding 300 extend substantially orthogonally to the longitudinal axis AL. This makes it possible to wind them in a simple manner during the second step E2 and to give them their final inclination (which follows the variations in thickness of the lateral edge and the yoke) during the third step E3.

[0082] Thus, the insertion of the lateral rim 220 here makes it possible to lower the portion of the second part 232 of the envelope 230 located opposite the central edge 213 of the body 210 to its final position, that is to say against the first part 231 of the envelope 230. As a variant, the method comprises a prior step of pressing the second part of the envelope before the insertion of the lateral rim.

[0083] Whatever the embodiment of the assembly method, the manufacturing method may include a final step of impregnating the windings 300, or even the stator 1 as a whole, with a resin.

[0084] The present invention is in no way limited to the embodiments described and shown, but those skilled in the art will be able to provide any variant in accordance with the invention.

[0085] For example, the side flanges could in particular be manufactured in one piece with the bodies of the teeth and the yoke, for example by punching and rolling a metal sheet. The stator assembly method is then adapted accordingly since it is no longer necessary to integrate or insert the side flanges in the envelopes.

[0086] As another example, the yoke could have a constant thickness. When the side edge has a variation in thickness, the winding can then have a more complex shape with a variation in thickness which compensates for the variation in thickness of the side edge.

[0087] In the figures, the side edge is shown as being flush with the central edge of the body. However, it could extend beyond or be set back from this central edge.

Claims

Claims

1. Stator (1) for axial flux electric machine comprising: - a yoke (100), in the overall shape of a disc, centered on a longitudinal axis (Al), - teeth (200) distributed on a main face of the yoke (100) around the longitudinal axis (Al), each tooth (200) comprising: H a body (210) rising from the main face (103) of the yoke (100) to a vertex (211) of the body (210), along the longitudinal axis (Al), said body (210) having a central edge (213) facing the longitudinal axis (Al) and a peripheral edge (214) opposite the central edge (213), H a pair of lateral edges (220) bordering the vertex (211) of the body (210), each lateral edge (220) extending from the central edge (213) of the body (210) towards the peripheral edge (214) of the body (210) in a lateral direction (A3), characterized in that at least one of the lateral edges (220): - has at least one dimension (E, L),measured in a direction orthogonal to the lateral direction (A3), which varies along the lateral direction (A3) and which is greater near the central edge (213) of the body (210) than near the peripheral edge (214) of the body (210), and / or - extends away from the peripheral edge (214) of the body (210).,

2. Stator (1) according to claim 1, wherein said lateral flange (220) extends at a distance, measured along the lateral direction (A3), from the peripheral edge (214) of the body (210) which is between 10% and 50% of a length of an edge of the top (211) of the body (210) measured between the central edge (213) and the peripheral edge (214) of the body (210).

3. Stator (1) according to claim 1 or 2, wherein said lateral rim (220) is made up of several elements (225) distinct from each other, said dimension (E, L) being greater at the element (225) closest to the central edge (213) of the body (210) than at the element (225) closest to the peripheral edge (214) of the body (210).

4. Stator (1) according to one of claims 1 to 3, wherein the lateral direction (A3) is parallel or orthogonal to the longitudinal axis (Al).

5. Stator (1) according to one of claims 1 to 4, wherein the dimension (E, L) decreases continuously along the lateral direction (A3).

6. Stator (1) according to one of claims 1 to 5, in which the yoke (100) has, vertically above said lateral edge (220), a thickness (C), measured parallel to the longitudinal axis (Al), which varies along the lateral direction (A3) such that the thickness (C) is greater in an area of ​​the yoke (100) spaced from the longitudinal axis (Al) than in an area of ​​the yoke (100) close to the longitudinal axis (Al).

7. An axial flux electrical machine comprising at least one stator (1) according to one of claims 1 to 6 and at least one rotor arranged to be driven in rotation by the at least one stator.

8. Method of assembling a stator (1) according to one of claims 1 to 6, each tooth (200) comprising an envelope (230) made of insulating material interposed between the body (210) of said tooth (200) and a winding (300) carried by said tooth (200), the method comprising a step of integrating said lateral rim (220) within the envelope (230).

9. Method of assembling a stator (1) according to claim 8, in which the step of integrating said lateral rim (220) within the casing (230) is carried out prior to positioning the casing (230) on the body (210).

10. A method of assembling a stator (1) according to claim 8, wherein the integration step comprises inserting said lateral flange (220) between the casing (230) and the body (210) in the lateral direction (A3), after positioning the casing (230) on the body (210).

11. Assembly method according to claim 10, in which the casing (230) and the body (210) delimit a hollow relief (240) of a shape complementary to the shape of said lateral rim (220) such that once inserted, said lateral rim (220) blocks any movement of the casing (230) parallel to the longitudinal axis (Al).

Images