Stator for axial-flow rotating electrical machine

Abstract

The invention relates to a stator for an axial flux type rotating electrical machine and a method for manufacturing the same. The stator comprises: a support ring (10) having N teeth (14), each of the N teeth extending along the axial member to a tip (24), the N teeth being separated from each other by N recesses (12), respectively; n windings (26) of electrically conductive wire, the N windings being wound around the N teeth (14), respectively; n pairs of flanges (36, 38) rigidly connected to the tips (24) of the N teeth (14), respectively, the two flanges of each of the N pairs of flanges extending laterally opposite each other and respectively facing each of the N windings (26). The N pairs of flanges (36, 38) are at least partially co-embedded in a piece forming the cover (50) and covering the N teeth (14) to close the N recesses (12) so that the N recesses can be cooled.

Description

[0001] The invention relates to a stator of an axial flow rotating electric machine.

[0002] One area of ​​application envisaged is particularly, but not exclusively, the area of ​​driving motor vehicles, in particular electric vehicles or hybrid vehicles.

[0003] A known axial-flow rotating electric machine generally comprises a stator and a disc-shaped rotor equipped with permanent magnets facing the stator.

[0004] Some other electric machines include a rotor positioned between two stators.

[0005] The stator of these motors comprises a support ring or yoke made of magnetic material, said ring having a plurality of teeth, for example fifteen teeth, extending along an axial component. The support ring is made from a stack of uniform so-called "electrical" sheets. These uniform sheets are obtained by simultaneously stamping and rolling one and the same "electrical" steel strip.

[0006] The teeth are regularly spaced apart from one another, defining free housings between the teeth. The housings have a substantially right-angled parallelepiped shape, while the teeth are substantially prismatic in shape. Thus, the teeth extend towards the center of the ring at a point in the radial component.

[0007] The teeth thus each comprise an electrically conductive wire winding forming a winding extending in a free housing.

[0008] In addition, the ring has two wings at the top of each of the teeth, opposite to each other relative to the teeth, extending directly opposite the winding. The two opposite wings are also made of magnetic material so as to be able to best guide the field lines outside the conductive wire winding.

[0009] Reference may be made to document FR 2 998 112 A1 which describes such a stator.

[0010] These stators make it possible to make highly efficient electric machines. However, the stator's conductive wire windings generate a large amount of heat energy that impairs the machine's performance.

[0011] The problem that arises and that the present invention aims to solve is therefore to provide a stator that is not only easy and inexpensive to manufacture but also has a better efficiency.

[0012] For the purpose of solving this problem and according to the first purpose, a stator of an axial-flow rotating electric machine is proposed, the stator of the axial-flow rotating electric machine comprising: a supporting ring made of a magnetic material, the supporting ring having N teeth each extending to the top as an axial part, N being an integer greater than 2, the N teeth being separated from each other by N accommodating parts, so that each of the teeth extends between two adjacent accommodating parts; N conductive wire windings, the N conductive wire windings being respectively wound around the N teeth, each of the N windings extending in the two adjacent accommodating parts; and N pairs of wings, the N pairs of wings made of a magnetic material being respectively fixed to the tops of the N teeth, the two wings of each pair of the N pairs of wings extending laterally opposite to each other relative to each of the N teeth and respectively extending to be directly opposite to each of the N windings.

[0013] Therefore, the N pairs of wings are at least partially embedded together in a single piece forming a cover and fitted on top of the N teeth to close the N housings, thereby enabling better cooling of the N housings.

[0014] Therefore, one feature of the present invention is to use a member that is suitable for forming a cover and includes N pairs of wings to close the accommodation portion so as to effectively cool the accommodation portion. This is because if the accommodation portion in which the windings extend is closed, the heat energy released by the Joule effect in the wire of the winding can be effectively discharged with the help of a refrigerant.

[0015] By dissipating this heat energy, the efficiency and performance of the motor are significantly improved.

[0016] On the other hand, the air gap, ie the space between the elements of the stator and the elements of the rotor, must be minimal in order to maintain good performance of the machine.

[0017] By means of the object of the present invention, despite the use of a single piece forming the cover, the top of the tooth and the wings of the tooth remain close to the rotor because the tooth is an integral part of the cover, as will be explained in more detail in the following description.

[0018] Furthermore, and as will also be explained below, said N pairs of wings are advantageously at least partially embedded together in a polymer material.

[0019] According to a particularly advantageous embodiment of the invention, the N housings are cooled by injecting a refrigerating fluid. For example, a cold gas inlet and an outlet for discharging the gas are provided for each of the housings. Thus, the heat energy released by the windings is exchanged with the cold gas, which, once heated, can be discharged via the outlet.

[0020] Preferably, the cooling fluid is guided within the N housings, within a pipe. Thus, a pipe is provided which extends around the wire winding inside each of the housings. The pipe is then connected to the cooling fluid circuit outside the housing.

[0021] Therefore, according to a further embodiment, and since the housing is sufficiently fluid-tight, an inlet and a corresponding outlet for a cooling liquid are provided. In this way, oil can be injected inside the housing, for example, for discharging the heat energy generated by the conductive wires of the winding.

[0022] According to a particularly advantageous embodiment of the invention, the two wings of each of the N pairs of wings together form a single element applied against the top of each of the N teeth. In this way, the magnetic field lines generated by the wire winding through the tooth extend uninterrupted through the wing. This also contributes to the performance of the motor.

[0023] According to a particularly advantageous but non-limiting variant implementation of the invention, the wings of the N pairs of wings are manufactured by sintering metal powder. This is also the case when the two wings of each of the N pairs of wings together form a single element. The wings are thus manufactured at advantageous costs and are easy to realize in said single piece to form the cover, as will be explained in more detail in the remainder of the description.

[0024] According to another variant implementation of the invention, the wings of the N pairs of wings are made of a composite material with metal reinforcement fibers. In this way, the metal reinforcement fibers are embedded in a matrix of polymer material. Thus, a single piece forming the cover comprises, over its thickness, wings formed of metal fibers. Thus, both the function of the wings as guides for field lines as close as possible to the rotor and the function of closure of the housing are obtained. Thus, such a feature makes it possible to obtain a perfectly fluid-tight housing. This facilitates the cooling of the conductive wire.

[0025] According to another object, a method for manufacturing a stator of an axial-flow rotating electric machine as described above is proposed. The method comprises the following steps: providing a support ring made of a magnetic material, the support ring having N teeth each extending to the top as an axial part, N being an integer greater than 2, the N teeth being separated from each other by N receiving parts, so that each of the teeth extends between two adjacent receiving parts; winding N conductive wire windings around the N teeth respectively to form N windings, each of the N windings extending in the two adjacent receiving parts; providing N pairs of wings made of a magnetic material, and the N pairs of wings are respectively fixed to the tops of the N teeth, the two wings of each pair of wings in the N pairs of wings extending laterally opposite to each other relative to each of the N teeth and respectively extending to face each of the N windings. And the N pairs of wings are at least partially embedded together in a single piece that forms a cover and is fitted on the top of the N teeth to close the N accommodating portions, thereby being able to better cool the N accommodating portions.

[0026] According to a first embodiment, N pairs of wings are overmolded together in a single piece using a polymer material to produce a single piece forming the cap. The wings are then connected together by portions of a wall made of a relatively fine polymer material. According to this embodiment, the wings are held between the tops against the teeth, while portions of the wall of the cap are applied directly against the tops.

[0027] According to a second embodiment, the two wings of each of the N pairs of wings are formed together in a single element and the single element is applied against the top of each of the N teeth. Thus, the two wings in a single element are applied against the top of the teeth and the N single elements are overmoulded directly on the ring to form the cover. In this way, the fluid tightness of the housing is further improved while ensuring perfect continuity of the field lines.

[0028] Preferably, the wing portions of the N pairs of wing portions are manufactured by sintering metal powder. In this way, it is easy to select and manufacture a suitable material for guiding the field lines.

[0029] According to a third implementation, the wings of said N pairs of wings are made of a composite material with metal reinforcement fibers. In this way, the single piece forming the cover is relatively uniform and has a zone forming the wing, which itself comprises one and the same continuous element. Moreover, as will be explained in more detail in the rest of the description, the part forming the cover is overmolded directly on the ring.

[0030] Other characteristics and advantages of the invention will become apparent on reading the following description of particular embodiments of the invention given for purposes of illustration and not limitation with reference to the accompanying drawings, in which: [ Figure 1 ] is a schematic top perspective view of elements of a stator according to one embodiment of the present invention; [ Figure 2 ] is combined with the first other element and according to the first embodiment [ Figure 1 ] a partial schematic diagram of a cross section of an element of an object; [ Figure 3 ] is combined with a second other element and according to the second embodiment [ Figure 1 ] a partial schematic diagram of a cross section of an element of an object; [ Figure 4 ] is combined with a third other element and according to a third embodiment [ Figure 1 ] a partial schematic cross-sectional view of an element of the object in a first implementation step; [ Figure 5 ]yes[ Figure 4 ] in a second implementation step; [ Fig. 6A ]to[ Figure 6C ] is as[ Figure 4 ]and[ Figure 5 ] is a schematic diagram of an implementation scheme of the present invention according to a third embodiment of the object; [ Figure 7 ] is a schematic perspective view of elements of a stator obtained according to a third embodiment; and [ Figure 8 ] is a partial schematic diagram of a radial cross section of the stator that is the object of the present invention.

[0031] [ Figure 1 ] shows a supporting ring 10 having a centre C and an axis of symmetry A. The ring 10 comprises a stack of a plurality of “electrical” steel sheets.

[0032] Thus, in the example presented here, which is by no means limiting, the ring 10 has fifteen U-shaped grooves 12 with cylindrical symmetry and square base and oriented on a straight line perpendicular to their intersecting axis of symmetry A. Furthermore, the U-shaped grooves 12 are regularly spaced from one another.

[0033] Thus, fifteen U-shaped grooves 12 define fifteen substantially prismatically shaped teeth 14 extending along an axial component parallel to the axis of symmetry A. Thus, the teeth 14 extend, for example, in axial direction over a thickness lying between one third and one quarter of the total thickness of the ring 10 .

[0034] The prismatically shaped toothing 14 is also oriented radially in the direction of the center C of the ring 10 . The length of the toothing 14 in this radial direction is therefore, for example, between one third and one quarter of the outer radius of the ring 10 .

[0035] It will be observed that each of the teeth 14 has, inside the ring 10 , an internal face 16 that is substantially concave, opposite an external face 18 that is substantially convex and oriented toward the outside of the ring 10 .

[0036] Each of the teeth 14 also has two opposite lateral faces 20 , 22 defined by two adjacent grooves 12 and a free top face 24 .

[0037] Each of the fifteen teeth 14 then receives a winding of an electrically conductive wire around an axis Z substantially parallel to the axis of symmetry A of the ring 10 .

[0038] Therefore, in [ Figure 2 ], there is a cross-sectional view of the toothing 14 located in a plane parallel to the axis of symmetry A of the ring 10 and near the inner face 16 which is also parallel to the middle plane defined by the toothing 14.

[0039] Therefore, in [ Figure 2 ] there are two opposite lateral faces 20, 22 and a winding 26 which is divided into two first half windings 28, 30 extending along the two opposite lateral faces 20, 22 and therefore in two adjacent grooves 12 which then form two adjacent receptacles.

[0040] Obviously, the windings 26 also extend towards the inner face 16 and towards the opposite outer face 18 .

[0041] The conductive wire winding 26 can generate, through the teeth 14 , a magnetic field parallel to the axis Z by supplying an electric current to the conductive wire. It will be observed that the magnetic field lines tend to move away from the axis Z outside the winding 26 .

[0042] It is thus possible for the field lines to be guided within the metallic material outside the winding 26 and beyond the toothing 14 .

[0043] Additionally, the electrical current tends to generate heat energy inside the housing through the Joule effect.

[0044] One object of the present invention is therefore to close the housing formed by the groove 12 so as to be able to effectively discharge the thermal energy accumulated in this housing.

[0045] Therefore, in [ Figure 2 ] also presents a first embodiment, which makes it possible to guide the field lines beyond the tooth portion 14 and to close the receiving portion formed by the groove 12.

[0046] According to this first embodiment, the two opposite lateral faces 20 , 22 of each of the teeth 14 are grooved at the rear of the free top face 24 so as to form two opposite recesses 32 , 34 .

[0047] Each of the teeth 14 is then associated with two first wings 36 , 38 obtained by sintering metal powder and each having a return 40 , 42 .

[0048] The two first wings 36 , 38 are advantageously joined together in a single piece at the end of the tooth 14 by a portion, not shown, extending along the inner face 16 and, oppositely, by a portion, also not shown, extending along the outer face 18 .

[0049] Thus, fifteen pairs of wings, regularly offset by 30° from one another, are overmolded by a layer of polymer material 44. The polymer material forms a film portion 46 between the wings 36, 38 of one and the same pair of wings, and also lines the space 48 extending between the wings 36, 38 of each of two consecutive pairs of wings, and this is achieved in a fluid-tight manner. In other words, the fifteen pairs of wings 36, 38 are partially embedded in the layer of polymer material 44.

[0050] Thus, all fifteen pairs of overmolded wings 36, 38 form a fluid-tight cover 50 which can then cover the ring. The return portions 40, 42 of each pair of wings 36, 48 are then engaged in the opposing recesses 32, 34, respectively, while the film portion 46 is applied against the top face 24 of each of the teeth 14.

[0051] By this embodiment, the air gap between the elements of the rotor and the elements of the stator can be very thin by means of the thin film portion 46. Then, the motor will maintain good performance.

[0052] Thus, the recess 12 forming the housing is closed and can be easily refrigerated, as will be explained below.

[0053] Now refer to [ Figure 3 ], which shows a second closed mode of the receiving portion formed by the groove 12.

[0054] Therefore, similar components will have the same Figure 2 ] have the same reference numerals as the objects in the figure with a prefix of “1”.

[0055] Therefore, in [ Figure 3], there are two opposite lateral faces 120, 122 and a winding 126, which is divided into two second half windings 128, 130 extending along the two opposite lateral faces 120, 122 and therefore in two adjacent grooves 112 that then form two adjacent accommodation portions.

[0056] The windings 126 also extend towards the inner face and the opposite outer face.

[0057] Therefore, according to this second embodiment, so that it is possible both to guide the field lines beyond the tooth 114 and to close the accommodation portion formed by the groove 112, the two second wings 136, 138 of one and the same pair of wings are formed together by a single element 135 applied against the top or free top surface 124 of each tooth in the tooth 114.

[0058] The element 135 is also obtained by sintering metal powder.

[0059] Thus, fifteen elements 135 regularly offset from one another by 30° are overmoulded by the further layer 144 of polymer material. Thus, the fifteen elements 115 defining each pair of wings 136, 138 are embedded in a layer of the further layer 144 of polymer material.

[0060] It will be observed that the element 115 made of magnetic material is directly in contact with the free top face 124 .

[0061] Thus, all fifteen elements 135 form a fluid-tight cover 150 which can then cover the ring.

[0062] Now refer to [ Figure 4 ], which shows a third closed mode of the receiving portion formed by the groove 12.

[0063] Therefore, with [ Figure 2 ] Similar elements to the objects of the present invention will have the same reference numerals prefixed with a “2”.

[0064] Therefore, in [ Figure 4 ], there are two opposite lateral faces 220, 222 and a winding 226, which is divided into two third half windings 228, 230 extending along the two opposite lateral faces 220, 222 and therefore extending in two adjacent grooves 212 that then form two adjacent accommodating portions.

[0065] The windings 226 also extend towards the inner face and the opposite outer face.

[0066] According to this third embodiment, so that the field lines can be guided beyond the teeth 214 and also the housing formed by the groove 212 can be closed, the fluid-tight cover 250 is formed as a single piece from a composite material comprising a portion of a metal fiber layer 252 and a portion of a glass fiber layer 254, the entirety of which is embedded in a matrix of a polymer material. The method for manufacturing the composite will be explained in the following description.

[0067] The portion of the metal fiber layer 252 impregnated with its matrix thus defines two third wings 236, 238 of one and the same pair of wings and the third wings 236, 238 are thus formed together. Portions of the metal fiber layer 252 are applied against the top or free top face 224 of each of the teeth 214.

[0068] like[ Figure 5 ], fifteen portions of the metal fiber layer 252 that are regularly offset by 30° from each other between fifteen portions of the glass fiber layer 254 are impregnated with a polymer matrix and overmolded together directly on the ring 210 to form the cover 250.

[0069] Reference [ Fig. 6A ]to[ Figure 6C ] will be given for obtaining Figure 5 Description of the method of cover 250 illustrated above.

[0070] therefore,[ Fig. 6A ] illustrates a first stack 260 of trapezoidal sections of fiberglass layers seen from below with a central aperture 262 which is also trapezoidal in shape. [ Fig. 6A ] Also illustrated is a second stack 264 of trapezoidal portions of a metal fiber layer.

[0071] The two stacks 260, 264 have substantially the same thickness. For example, the stacks 260, 264 each comprise five crossed fiber layers.

[0072] Therefore, the width L of the five layers of the second stack 264 is from [ Fig. 6A ] View from below to [ Figure 6C ]The floor plan presented on the .

[0073] In addition, the five layers of the first stack 260 have a central aperture 262, the central aperture 262 being located at [ Fig. 6A ] shows the view from below and [ Figure 6C ]The plan views presented above widen in the width direction.

[0074] Therefore, if [ Figure 6B], the second stack 264, seen at the edge, has two opposite lateral edges 266, 268 in the bevel, while the first stack 260 also has two opposite inner edges 270, 272 in the bevel, the inner edges 270, 272 being applied oppositely against the two opposite lateral edges 266, 268. In this way, the corresponding superposition of the lateral edges 266, 268 and the inner edges 270, 272 maintains a constant thickness of five fiber layers.

[0075] Thus, fifteen first and second stacks are fitted edge to edge in a ring in the mould so that the widest layer of the second stack 264 is applied against the bottom of the mould.

[0076] The ring 10 is then adjusted in the mould so that the free top face 224 of each of the teeth is applied precisely and respectively against the narrowest layer of each of the second stacks 264 .

[0077] And then, a polymer material is injected into the mold, preferably a thermoplastic polymer material that is viscous at temperatures above 100° C. The polymer material impregnates all the layer stacks.

[0078] In this way, after the polymer has cooled, Figure 7 The cover 250 is made of a single piece as shown in the perspective view above, for illustrative reasons Figure 7 There is no ring on it.

[0079] It will be observed that [ Figure 6B The two inclined opposite lateral edges 266, 268 of the second stack 264 shown in FIG. 1 then form a Figure 5 ] two opposing wings 236, 238 shown on.

[0080] therefore,[ Figure 8 ] In diametric section and according to a particular embodiment, the cover 250 enclosing the free space 212 is illustrated. It can be seen that the ring 210 is mounted inside a circular U-shaped receiving portion 280, which cooperates with the cover 250 in a fluid-tight manner.

[0081] The winding 226 can be seen around the tooth 214. Portions of a metal fiber layer 252 impregnated with a polymer can also be seen, which portions of the metal fiber layer 252 are applied against the free top face 224 of the tooth 214, respectively.

[0082] Thus, elements of the rotor of the electric machine will be able to extend facing these impregnated portions of the metal fiber layer 252 .

[0083] Thus, the circular U-shaped receiving portion 280 has radial inlet orifices 282, 284 for refrigerating the fluid present in the free space 212. And the circular U-shaped container 280 also has axial outlet orifices 286, 288 for discharging the hot fluid. And in this way, through the fluid-tight cover 250, the refrigeration fluid can circulate around the winding 226 without leakage in order to cool the winding 226.

[0084] In this way, the efficiency of the motor is not affected.

[0085] The cover 250 has the advantage of having magnetic parts comprising metal fibers extending on the surface of the cover 250. And these magnetic parts can interact freely with the elements of the rotor. Under these conditions, the air gap is maintained and the motor maintains all its performance.

[0086] The ring 210 described above has fifteen teeth. According to certain other embodiments, the ring 210 has fewer teeth and according to other embodiments, the ring 210 has more teeth.

[0087] Obviously, the number of wing pairs is adjusted accordingly.

Claims

1. A stator of an axial-flow rotating electric machine, the stator of the axial-flow rotating electric machine comprising: - a support ring (10), the support ring (10) being made of a magnetic material, the support ring having N teeth (14), each of the N teeth (14) extending as an axial part to a top (24), N being an integer greater than 2, the N teeth being separated from each other by N receiving portions (12), so that each of the teeth extends between two adjacent receiving portions; - N conductive wire windings (26), each of the N conductive wire windings (26) being wound around the N teeth (14), and each of the N windings extending in two adjacent receiving portions (12); - N pairs of wings (36, 38), the N pairs of wings (36, 38) are made of magnetic material and are respectively fixed to the tops (24) of the N teeth (14), the two wings of each pair of the N pairs of wings extending laterally opposite to each other relative to each of the N teeth and respectively extending to face each of the N windings (26); It is characterized in that the N pairs of wings (36, 38) are at least partially embedded together in a single piece forming a cover (50) and fitted on the top of the N teeth (14) to close the N receiving parts (12), thereby enabling the N receiving parts to be cooled.

2. The motor stator according to claim 1, characterized in that: The N receiving portions (12) are cooled by injecting a refrigerant fluid.

3. The motor stator according to claim 2, characterized in that: The refrigerant fluid is guided within the N containers (12) and within the pipes.

4. The motor stator according to any one of claims 1 to 3, characterized in that: The two wings (136, 138) of each of the N pairs of wings together form a single element (135) to be applied against the top (124) of each of the N teeth.

5. The motor stator according to any one of claims 1 to 4, characterized in that: The wing parts (136, 138) in the N pairs of wing parts are manufactured by sintering metal powder.

6. The motor stator according to any one of claims 1 to 4, characterized in that: The wing portions (236, 238) of the N pairs of wing portions are made of a composite material having metal reinforcement fibers.

7. A method for manufacturing a stator of an axial-flow rotating electrical machine according to any one of claims 1 to 6, the method comprising the following steps: - providing a support ring (10) made of magnetic material, the support ring having N teeth (14), each of the N teeth (14) extending as an axial part to a top (24), N being an integer greater than 2, the N teeth being separated from each other by N receiving portions (12), so that each of the teeth extends between two adjacent receiving portions; - Winding N conductive wire windings around the N teeth (14) respectively to form N windings (26), each of the N windings extending in two adjacent receiving portions (12); - providing N pairs of wings (36, 38), the N pairs of wings (36, 38) being made of magnetic material and being fixed to the tops (24) of the N teeth (14), respectively, the two wings of each pair of the N pairs of wings extending laterally opposite to each other relative to each of the N teeth and respectively extending to face each of the N windings (26); Characterized in that the N pairs of wings (36, 38) are at least partially embedded together in a single piece forming a cover (50), and the N teeth (14) are covered to close the N receiving portions (12), thereby enabling the N receiving portions to be cooled.

8. The method for manufacturing a stator according to claim 7, characterized in that The two wings (136, 138) of each of the N pairs of wings are formed together in a single element, and the single element is applied against the top (124) of each of the N teeth (14).

9. The method for manufacturing a stator according to claim 7 or 8, characterized in that: The wing parts (136, 138) in the N pairs of wing parts are manufactured by sintering metal powder.

10. The method for manufacturing a stator according to claim 7 or 8, characterized in that: The wing portions (236, 238) of the N pairs of wing portions are made of a composite material having metal reinforcement fibers.

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