Improved tooth for axial flux electric machine stator

Abstract

Stator (24) for an axial flux electric machine, of the type comprising windings (26) of electrical conductors arranged around ferromagnetic magnetic field-guiding masses called teeth (28). Each tooth (28) has a general prismatic shape comprising two isometric bases (FB) connected by lateral faces (FA, FE). The isometric bases (FB) of each tooth (28) are formed by radial faces of the tooth (28). Figure for the abbreviation: Figure 2

Description

Title of the invention: Improved tooth for axial flux electric machine stator

[0001] The invention relates to the field of axial flux electrical machines, more particularly a stator for an axial flux electrical machine.

[0002] An axial flux electric machine comprises at least one rotor intended to rotate relative to a stator such that the magnetic field lines between the rotor and the stator are parallel to the axis of rotation of the rotor.

[0003] This type of electric machine is increasingly used in electric motor vehicles, in particular to form a drive motor for the vehicle or for equipment of that vehicle.

[0004] A stator for an axial flux electric machine comprising windings of electrical conductors arranged around ferromagnetic magnetic field guiding masses, called teeth, is already known in the prior art. Each tooth has substantially a general prism shape comprising two isometric bases connected by lateral faces.

[0005] It will be recalled that two plane figures or two faces are said to be isometric when one of them (called "image") is the result of one or more geometric transformations from the other (called "initial"), these geometric transformations being chosen from a translation, a rotation and a reflection.

[0006] Thus, a prism is a solid delimited by isometric bases connected to each other by lateral faces.

[0007] The teeth of a stator of an axial flux electric machine have substantially general prism shapes, the faces or bases of these teeth not necessarily forming perfect polygons.

[0008] In what follows, a tooth face or base perpendicular to the axis of rotation of the rotor will be referred to as "axial", a tooth face or base perpendicular to a radius extending from the axis of rotation of the rotor will be referred to as "radial", and a tooth face or base delimiting the notch formed by the angular space between two teeth will be referred to as "notch".

[0009] Thus, in the prior art, on the one hand, the isometric bases delimiting a tooth are formed by two axial faces of the tooth. On the other hand, the lateral faces of the tooth comprise two notch faces which diverge from each other as they move away from the axis of rotation of the rotor, these notch faces connecting a small radial face of the tooth, radially internal, to a large radial face of the tooth, radially external.

[0010] This shape of the teeth limits the notch formed by the angular space between two successive teeth.

[0011] However, to optimize the magnetic flux through a tooth, the tooth is usually formed by a set of contiguous plates made of ferromagnetic material. Thus, a tooth can be formed by several dozen ferromagnetic plates, for example, eighty. These ferromagnetic plates are arranged so that their faces are substantially parallel to the magnetic field lines passing through the tooth. Therefore, the ferromagnetic plates are arranged face to face, generally by stacking them in a radial direction.

[0012] However, to obtain a tooth with divergent notch faces as mentioned above, by radial stacking of ferromagnetic plates, it is necessary to use ferromagnetic plates of evolving dimensions, so that the faces of the radially external plates are larger than the faces of the radially internal plates.

[0013] This therefore necessitates the use of numerous ferromagnetic plates of varying dimensions to manufacture the teeth of an axial flux machine stator. This heterogeneity in the dimensions of the ferromagnetic plates complicates the stator's manufacture and increases its manufacturing cost.

[0014] The invention aims in particular to simplify the manufacture of the teeth of an axial flux machine stator.

[0015] To this end, the invention relates to a stator for an axial flux electric machine, of the type comprising windings of electrical conductors arranged around ferromagnetic magnetic field guiding masses, called teeth, each tooth having a general prism shape comprising two isometric bases connected by lateral faces. The isometric bases of each tooth are formed by radial faces of the tooth.

[0016] Because the isometric bases of each tooth are formed by radial faces of the tooth, this tooth can be manufactured by a radial stacking of plates whose faces, including those forming the bases, are all isometric. Plates of identical dimensions can thus be used to form all the stator teeth. The homogeneity of the plate dimensions simplifies the manufacturing of the stator teeth and therefore reduces the manufacturing costs of the stator.

[0017] Other optional features of the invention will be stated below.

[0018] The isometric bases of at least one tooth are substantially rectangular. This shape is very simple to produce.

[0019] The isometric bases of at least one tooth each have a peripheral contour comprising two opposing sides, called axial sides, contributing to the delimitation of two opposing axial faces of the tooth, and two opposing sides, called notch sides, contributing to the delimitation of two opposing notch faces of the tooth, the notch sides being connected to the axial sides by transition portions of the peripheral contour such that the Two opposing notched faces of the tooth define a recess in the overall prismatic shape of the tooth. Thus, the recesses formed in a tooth advantageously create housings for the winding associated with the tooth carrying that winding, thereby optimizing the retention of the winding on the tooth.

[0020] The general prism shape of at least one tooth is chosen from a right prism and an oblique prism. Thus, prismatic teeth can be produced in various shapes.

[0021] The teeth are carried by a crown forming a support head so as to carry each one at least one winding.

[0022] Each tooth carries two windings extending axially respectively on either side of the cylinder head.

[0023] The stator comprises at least one electrically insulating sheath interposed between at least one tooth, referred to as the insulated tooth, and the winding surrounding this insulated tooth, referred to as the insulated winding. The insulating sheath comprises extensions at each of its axial ends folded over the insulated winding substantially parallel to the axial faces of the insulated tooth. Thus, before mounting a winding on a tooth, the insulating sheath can be arranged inside the winding, and then the assembly formed by the winding and the insulating sheath can be fitted around a corresponding tooth. Therefore, mounting the winding and the sheath on the tooth is very simple.

[0024] Each ferromagnetic plate includes a passage hole for a means of fixing the plates together, for example a rivet, a screw or a pin, the passage holes provided in the ferromagnetic plates being aligned with each other.

[0025] At least one tooth comprises contiguous plates of ferromagnetic material.

[0026] The isometric bases of at least one tooth each have a peripheral contour comprising two opposite sides, called axial, participating in the delimitation of two opposite axial faces of the tooth, the axial sides of the peripheral contour comprising a notch intended to cooperate with a complementary element for positioning the plates to optimize their alignment.

[0027] The faces of the contiguous plates made of ferromagnetic material of at least one tooth are substantially parallel to the radial faces of that tooth.

[0028] The faces of the contiguous plates in ferromagnetic material of at least one tooth are substantially parallel to the notch faces of that tooth.

[0029] The invention also relates to an axial flux electric machine comprising at least one stator as defined above. Brief description of the figures

[0030] The invention will be better understood upon reading the following description given only by way of example and made with reference to the attached drawings in which:

[0031] [Fig.1] is a perspective view of an axial flux machine according to the invention comprising a stator according to a first embodiment;

[0032] [Fig.2] is a front view of the stator of the axial flux machine of [Fig. 1];

[0033] [Fig.3] is a perspective view of a tooth of the stator of [Fig.2];

[0034] [Fig.4] is a perspective view of an electrical conductor winding intended to be arranged around the tooth of the [Fig.3];

[0035] [Fig.5] is a front view of a first variant embodiment of the tooth presented in Figure 3;

[0036] [Fig.6] is a front view of a second embodiment of the tooth presented in Figure 3;

[0037] [Fig.7] is a perspective view of a third embodiment of the tooth represented in Figure 3;

[0038] [Fig.8] is a perspective view of a fourth embodiment of the tooth represented in Figure 3;

[0039] [Fig.9] is a perspective view of a fifth embodiment variant of the tooth represented in Figure 3;

[0040] [Fig. 10] is a perspective view of a sixth embodiment variant of the tooth represented in Figure 3;

[0041] [Fig. 11] is a partial perspective view of a stator according to a second mode of realization of the invention; and

[0042] [Fig. 12] is a partial perspective view of a stator according to a third mode of realization of the invention. Detailed description

[0043] Figure 1 shows an axial flux electric machine according to a first embodiment of the invention, designated by the general reference numeral 20. This machine 20 is intended, in the example described, to form a drive motor for a motor vehicle. The machine 20 could also be used to drive motor vehicle equipment.

[0044] The electric machine 20 comprises at least one rotor 22 intended to rotate relative to a stator 24 such that the magnetic field lines between each rotor 22 and the stator 24 are parallel to the X axis of rotation of each rotor 22.

[0045] In the embodiment illustrated in [Fig.1], the electric machine 20 comprises two rotors 22 between which the stator 24 is axially interposed.

[0046] With particular reference to [Fig. 2], it can be seen that the stator 24 comprises windings 26 of electrical conductors arranged around ferromagnetic magnetic field-guiding masses. In what follows, these ferromagnetic masses are called teeth 28. The teeth 28 are arranged circumferentially around the X axis of rotation of the rotors 22.

[0047] As can be seen in more detail in [Fig. 3], each tooth 28 of the stator 24 has a general prismatic shape comprising two isometric bases FB connected by four lateral faces, namely two opposing axial lateral faces FA and two opposing notch lateral faces FE, in accordance with the definitions specified above. Thus, the isometric bases FB of each tooth 28 are formed by two opposing radial faces of the tooth 28, in accordance with the definition specified above.

[0048] It should be noted that the isometric bases FB of the tooth 28 shown in [Fig. 3] are substantially rectangular, the prism formed by the tooth 28 being right. In the example illustrated in [Fig. 1], all the teeth 28 have a general right prism shape, and the isometric bases FB of all the teeth are substantially rectangular.

[0049] Referring again to [Fig. 3], it can be seen that at least one tooth 28 of the stator 24 comprises contiguous plates 30 made of ferromagnetic material. Preferably, as in the illustrated example, each tooth 28 of the stator 24 comprises contiguous plates 30.

[0050] In the example illustrated in [Fig.3], the faces of the adjoining plates 30 of the tooth 28 are substantially parallel to the radial faces of this tooth 28, i.e. to the isometric bases FB of the tooth 28. According to another example not illustrated, the faces of the adjoining plates 30 of at least one tooth 28 are substantially parallel to the notch faces FE of this tooth 28.

[0051] In the illustrated example, the faces of the contiguous plates 30 of all the teeth 28 of the stator 24 are substantially parallel to the radial faces of the corresponding teeth 28, that is to say to the isometric bases FB of the corresponding teeth 28.

[0052] If necessary, it is possible to provide on the stator 24 teeth 28 of a first type whose contiguous plates 30 are substantially parallel to the radial faces of the corresponding teeth 28, that is to say, to the isometric bases FB of the corresponding teeth 28, and teeth 28 of a second type whose contiguous plates 30 are substantially parallel to the notch faces of the corresponding teeth 28. Thus, one could provide on the stator 24 teeth 28 of the first type alternating circumferentially with teeth 28 of the second type.

[0053] As can be seen in Figures 2 and 4, the stator 24 comprises at least one electrically insulating sheath 32, made of conventional material, interposed between at least one tooth, called insulated tooth 28, and the winding surrounding this insulated tooth 28, called insulated winding 26. Preferably, as shown in [Fig.2], each tooth 28 of the stator 24 is insulated from its corresponding winding 26 by an insulating sheath 32.

[0054] With particular reference to [Fig. 4], it can be seen that each insulating sheath 32 includes extensions 32P at each of its axial ends folded over the insulated winding 26 corresponding substantially parallel to the axial faces FA of the corresponding insulated tooth 28.

[0055] In the variants and other embodiments that will be described below, analogous elements are designated by identical references.

[0056] Figure 5 shows one of the isometric bases FB of a tooth 28 according to a first embodiment. In this first embodiment, the two isometric bases FB of the tooth 28 each have a peripheral contour comprising two opposing sides, called axial sides FBA, which contribute to the delimitation of two opposing axial faces FA of the tooth 28. This peripheral contour also comprises two opposing sides, called notch sides FBE, which contribute to the delimitation of two opposing notch faces FE of the tooth 28. The notch sides FBE are connected to the axial sides FBA by transition portions of the peripheral contour, forming fillets 34, so that the two opposing notch faces FE of the tooth 28 define a recess 36 in the general prism shape of the tooth 28.

[0057] Figure 6 shows one of the isometric bases FB of a tooth 28 according to a second embodiment. This second embodiment of the tooth 28 differs from the first embodiment of this tooth 28 in that the transition parts of the peripheral contour form bevels 38.

[0058] The recesses 36, delimited by the fillets 34 or the bevels 38, advantageously form housings for the winding 26 associated with the tooth 28 carrying this winding 26, optimizing the retention of the winding 26 on the tooth 28.

[0059] Figure 7 shows a tooth 28 according to a third embodiment. This third embodiment of the tooth 28 differs from the second embodiment of this tooth 28 in that the adjacent plates 30 each include an opening 40 for the passage of a means for fastening the plates together. The openings 40 in the plates 30 are aligned with each other so as to allow the passage of a fastening means such as a rivet, a screw, or a pin for fastening the plates 30 together, and also, where applicable, for fastening the tooth 28 to a support.

[0060] Figure 8 shows a tooth 28 according to a fourth embodiment. This fourth embodiment of tooth 28 differs from the second embodiment of this tooth 28 (illustrated in Figure 6) in that the axial sides FBA of the peripheral contour of the bases FB have a notch 42 intended to cooperate with a complementary element (not shown) for positioning the plates 30 in order to optimize their alignment. In this fourth embodiment of tooth 28, the notch 42 has a polygonal shape. In contrast, in the fifth embodiment of tooth 28, shown in Figure 9, the notch 42 has a semi-circular shape.

[0061] Figure 10 shows a tooth 28 according to a sixth embodiment. This sixth embodiment of tooth 28 differs from tooth 28 illustrated in Figure 3 in that the prism formed by tooth 28 is, in this case, oblique.

[0062] Figure 11 shows a stator 24 according to a second embodiment of the invention. In this case, the teeth 28 are supported by a crown forming a yoke 44 such that each tooth carries at least one winding (not shown). In this second embodiment of the invention, each tooth 28 carries two windings (not shown) extending axially on either side of the yoke 44. In contrast, in the third embodiment of the stator 24 according to the invention, shown in Figure 12, each tooth 28 carries only one winding (not shown).

[0063] The invention is not limited to the embodiments presented, and other embodiments will be obvious to those skilled in the art. In particular, it is possible to provide teeth 28 on the stator 24 according to one of the variants as described above, alternating circumferentially with teeth 28 of another variant among those described above. List of references:

[0064] 20: electrical machine

[0065] 22: rotor

[0066] 24: stator

[0067] 26: winding of electrical conductor

[0068] 28: tooth

[0069] 30: contiguous plates made of ferromagnetic material

[0070] 32: electrically insulating sheath

[0071] 32P: extensions of the sheath

[0072] 34: leave

[0073] 36: indentation

[0074] 38: bevel

[0075] 40: opening for the passage of a fastening means

[0076] 42: notch

[0077] 44: cylinder head

[0078] FA: opposite axial lateral faces

[0079] FB: isometric bases

[0080] FE: Opposite lateral faces of notch

[0081] FBA: axial opposite sides of the peripheral contour of the isometric bases

[0082] FBE: opposite sides of the notch on the peripheral contour of the isometric bases

[0083]

Claims

Claims

1. Stator (24) for axial flux electrical machine, of the type comprising windings (26) of electrical conductors arranged around ferromagnetic magnetic field guiding masses, called teeth (28), each tooth (28) having a general prism shape comprising two isometric bases (FB) connected by lateral faces (FA, FE), characterized in that the isometric bases (FB) of each tooth (28) are formed by radial faces of the tooth (28).

2. Stator (24) according to claim 1, wherein the isometric bases (FB) of at least one tooth (28) are substantially rectangular.

3. Stator (24) according to claim 1 or 2, in which the isometric bases (FB) of at least one tooth (28) each have a peripheral contour comprising two opposite sides, called axial sides (FBA), participating in the delimitation of two opposite axial faces (FA) of the tooth (28), two opposite sides, called notch sides (FBE), participating in the delimitation of two opposite notch faces (FE) of the tooth (28), the notch sides (FBE) being connected to the axial sides (FBA) by transition parts (34; 38) of the peripheral contour so that the two opposite notch faces (FE) of the tooth (28) delimit a depression (36) in the general prism shape of the tooth (28).

4. Stator (24) according to any one of claims 1 to 3, wherein the general prism shape of at least one tooth (28) is selected from a straight prism and an oblique prism.

5. Stator (24) according to any one of claims 1 to 4, in which the teeth (28) are carried by a crown forming a support yoke (44) so ​​as to each carry at least one winding (26).

6. Stator (24) according to claim 5, in which each tooth (28) carries two windings (26) extending axially respectively on either side of the yoke (44).

7. Stator (24) according to any one of claims 1 to 6, comprising at least one electrically insulating sheath (32) interposed between at least one tooth (28), called the insulated tooth (28), and the winding (26) surrounding this insulated tooth (28), called the insulated winding, the insulating sheath (32) comprising extensions (32P) at each of its axial ends folded over the insulated winding (26) substantially parallel to the axial faces (FA) of the insulated tooth (28).

8. A stator (24) according to any one of claims 1 to 7, wherein at least one tooth (28) comprises adjoining plates (30) made of ferromagnetic material.

9. Stator (24) according to claim 8, in which the ferromagnetic plates (30) each comprise an orifice (40) for the passage of a means for fixing the plates (30) together, for example a rivet, a screw or a pin, the passage orifices (40) provided in the ferromagnetic plates (30) being aligned with each other.

10. Stator (24) according to claim 8 or 9, in which the isometric bases of at least one tooth (28) each have a peripheral contour comprising two opposite sides, called axial (FBA), participating in the delimitation of two opposite axial faces (FA) of the tooth (28), the axial sides (FBA) of the peripheral contour comprising a notch (42) intended to cooperate with a complementary member for positioning the plates (30) to optimize their alignment.

11. Stator (24) according to any one of claims 8 to 10, in which the faces of the adjoining plates (30) made of ferromagnetic material of at least one tooth (28) are substantially parallel to the radial faces (FB) of this tooth (28).

12. Stator (24) according to any one of claims 8 to 10, in which the faces of the adjoining plates (30) made of ferromagnetic material of at least one tooth (28) are substantially parallel to the notch faces (FB) of this tooth (28).

13. Axial flux electrical machine (20), characterized in that it comprises at least one stator (24) according to any one of the preceding claims.

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