Axial flux rotating electric machine

Abstract

The invention relates to an electric machine (1) intended to be fixed to the rear of a reduction device (2) and comprising: - a stator (16) including a support structure (25), a plurality of teeth (19) supported by the support structure (25) and coils (22); - a rear rotor (18) and a front rotor (17) which are arranged axially on either side of the stator (16) and which are rotationally fixed to a rotor shaft (8); and - a half-casing (9) intended to be fixed to a bell (4) of the reduction device (2); said electric machine (1) comprising a rear roller bearing (43) interposed between a rear portion of the rotor shaft (8) and the half-casing (9), the rotor shaft (8) comprising a front portion intended to be guided in rotation by a front roller bearing (42) intended to be carried by the reduction device (2), the support structure (25) being made of an electrically insulating material. Figure for the abbreviation: 2.

Description

Title of the invention: Rotating axial flux electric machine technical field

[0001] The invention relates to a rotating electrical machine with axial flux, in particular for an electric or hybrid vehicle, as well as an assembly comprising a reduction device and a rotating electrical machine with axial flux.

[0002] The invention relates more particularly to a rotating axial flux electrical machine comprising a stator and two rotors arranged axially on either side of the stator. Technological background

[0003] US patent 20220368202 discloses a rotating axial flux electrical machine comprising a stator and two rotors arranged axially on either side of the stator. The stator comprises a plurality of coils distributed around the X-axis and mounted on a support structure. The stator support structure is configured to guide the rotors in rotation. To this end, two roller bearings are interposed between the stator support structure and each of the rotors. In order to provide sufficient mechanical strength for guiding the rotors in rotation while limiting eddy current losses, the support structure is made of a steel alloy exhibiting high electrical resistance.

[0004] Such an electrical machine is not entirely satisfactory, particularly in that the eddy current losses in the support structure remain substantial. Summary of the invention

[0005] One idea underlying the invention is to propose a rotating axial flux electrical machine comprising a stator and two rotors arranged axially on either side of the stator and in which eddy current losses are further limited.

[0006] Another idea underlying the invention is to propose a rotating axial flux electrical machine of the aforementioned type which is particularly simple to manufacture, compact and / or allows for efficient cooling of the stator coils.

[0007] According to a first aspect, the invention provides an electrical machine intended to be fixed to the rear of a reduction device and comprising: - a stator comprising a support structure having an annular shape centered around an X-axis, a plurality of teeth distributed around the X-axis and supported by the support structure, and coils comprising a winding and which are carried by the teeth; - a rear rotor and a front rotor which are axially arranged on either side of the stator and which are rotationally fixed to a rotor shaft that rotates about the X-axis, said rotor shaft passing through the support structure and comprising a front portion intended to be coupled to a gear system of the reduction device; and - a half-casing intended to be fixed to a bell of the reduction device and configured to form with said bell a housing space in which the stator, the front rotor and the rear rotor are housed; the support structure being fixed to said half-casing; said electrical machine being notable in that: - it includes a rear bearing interposed between a rear portion of the rotor shaft and the half-casing; - the front portion of the rotor shaft is intended to be guided in rotation by a front roller bearing intended to be supported by the reduction device; and - the support structure is made of an electrically insulating material.

[0008] Thus, since the rotor shaft is guided in rotation, on the one hand, by the half-casing and, on the other hand, by the reduction device, the stator support structure no longer has to perform a guiding function for said rotor shaft. This support structure can therefore be made of a material less mechanically resistant than a metal, and more particularly, an electrically insulating material. Eddy current losses in the stator are thus further reduced.

[0009] According to embodiments, such an electrical machine may include one or more of the following characteristics.

[0010] According to one embodiment, the support structure is made of a polymer material.

[0011] According to one embodiment, the polymer material is selected from polyamides, in particular long-chain polyphthalamides and polyamides 6.6, polyether sulfones, and polyphenylene sulfides. The polymer material may be reinforced with fibers, in particular glass fibers.

[0012] According to one embodiment, the front bearing is fitted onto the front portion of the rotor shaft and is intended to be arranged radially inside a housing provided in the bell.

[0013] According to another embodiment, not shown, the gear system of the reduction device comprises an input shaft, the front bearing being fitted onto said input shaft, the front portion of the rotor shaft being rotationally coupled to the input shaft and guided in rotation by it.

[0014] According to one embodiment, the support structure comprises a front flange and a rear flange which are fixed to each other and between which the teeth are held of the stator.

[0015] According to one embodiment, each of the front and rear flanges comprises a side having a radial orientation, said sides having impressions each receiving by form fitting an axial end of one of the teeth.

[0016] According to one embodiment, the support structure has an internal periphery which is spaced from the rotor shaft by a radial space which is devoid of a bearing.

[0017] According to one embodiment, the electrical machine includes an interconnector which is housed in the support structure and which has four conductive traces (U, V, W and neutral), said conductive traces connecting, on the one hand, the windings of the coils to each other and, on the other hand, connecting them to a connector intended to be connected to an electrical circuit of a vehicle.

[0018] According to one embodiment, the interconnector is housed in a housing provided in the rear flange which projects radially towards the rear relative to the side of the rear flange and is arranged radially outside the rear rotor.

[0019] According to one embodiment, the support structure comprises an outer periphery carrying two sealing O-rings designed to cooperate with the bell of the reduction device so as to create, between said outer periphery and the bell, a sealed annular chamber for receiving a cooling fluid. The outer periphery further comprises a plurality of spray orifices distributed circumferentially around the X-axis and opening radially opposite the stator coils. Thus, the structure of the cooling fluid circuit is particularly simple and compact.

[0020] According to one embodiment, the rear rotor comprises a support disc including an external portion and an internal coupling portion, the external portion carrying a plurality of permanent magnets distributed around the X axis and being positioned axially opposite the stator, the internal coupling portion being rotationally coupled to the rotor shaft and being offset forward relative to the external portion.

[0021] According to one embodiment, the internal coupling portion of the rear rotor support disc is arranged radially inside the stator.

[0022] According to one embodiment, the rear bearing support is arranged radially inside the outer portion.

[0023] According to one embodiment, the front rotor comprises a support disc including an external portion and an internal coupling portion, the external portion carrying a plurality of permanent magnets distributed around the X-axis and being positioned axially opposite the stator, the internal coupling portion being rotationally coupled to the rotor shaft and being offset rearward relative to the external portion.

[0024] According to one embodiment, the internal coupling portion of the front rotor support disc is arranged radially inside the stator.

[0025] According to one embodiment, the front bearing support is arranged radially inside the outer portion of the front rotor support disc.

[0026] According to a second aspect, the invention provides an assembly comprising an electric machine of the aforementioned type and a reduction device comprising a bell which is fixed to the half-casing of the electric machine and which defines with the half-casing the housing space in which the stator, the front rotor and the rear rotor are housed.

[0027] According to an embodiment of the second aspect mentioned above, the reduction device comprises a bell which is fixed to the half-casing of the electric machine and defines with the half-casing the housing space in which the stator, the front rotor and the rear rotor are housed, the bell having a cooling fluid inlet which opens into the sealed annular chamber and a cooling fluid outlet which is in fluidic communication with the sealed annular chamber. Brief description of the figures

[0028] The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent from the following description of several particular embodiments of the invention, given solely by way of illustration and not limitation, with reference to the accompanying drawings.

[0029] [Fig-1] Fig. 1 is a rear perspective view of an assembly comprising a electric machine and a reduction device.

[0030] [Fig.2] The [Fig.2] is a cross-sectional view of the whole of the [Fig.1].

[0031] [Fig.3] Fig.3 is a front perspective view of the electric machine of the [Fig.l].

[0032] [Fig.4] The [Fig.4] is an exploded view of the electrical machine.

[0033] [Fig.5] The [Fig.5] is a partial exploded view of the stator.

[0034] [Fig.6] The [Fig.6] is an exploded view of a stator tooth.

[0035] [Fig.7] The [Fig.7] is an exploded view of the stator. Description of the implementation methods

[0036] In the description and claims, the terms "external" and "internal," as well as the orientations "axial" and "radial," shall be used to designate, according to the definitions given in the description, elements of the electric machine and the reduction device. By convention, the X-axis of rotation of the rotors defines the "axial" orientation. The terms "external" and "internal" are used to define the relative position of one element with respect to another, with reference to the X-axis. An element close to the X-axis is thus described as internal, as opposed to an element external located radially on the periphery. Furthermore, the terms "rear" and "front", respectively designated by the abbreviations "AR" and "AV" in the figures, are used to define the relative position of one element with respect to another along the X axis. By convention, the electric machine is considered to be located at the rear of the reduction device regardless of their relative position with respect to the front and rear of the vehicle for which they are intended.

[0037] In the example described below, the electric machine 1 is a permanent magnet synchronous machine. It can notably be used as a motor to power an electric or hybrid vehicle and / or as a generator for such a vehicle.

[0038] Figure 1 illustrates an assembly comprising an axially flux rotating electrical machine 1 and a reduction device 2 associated with said electrical machine 1. The reduction device 2 includes a gear system, not shown, for increasing the torque delivered by the electrical machine 1 to the wheels. The reduction device 2 may have a single reduction ratio or several. In the latter case, the reduction device 2 forms a gearbox.

[0039] The reduction device 2 comprises a main housing 3 in which the gear system is housed. The reduction device 2 also comprises a bell 4 which projects from the main housing 3, towards the electrical machine 1 and which is fixed to it.

[0040] It can be seen in [Fig.2] that the bell 4 has an external skirt 5 and a bottom wall 6 separating the interior of the main enclosure 3 from the interior of the bell 4. The bottom wall 6 of the bell 4 has an opening 7 allowing the passage of a rotor shaft 8 of the electric machine 1 so that it can couple with an input shaft, not shown, of the reduction device 3.

[0041] The electric machine 1 has, at the rear, a half-casing 9, which is intended to be fixed to the bell 4 of the reduction device 2. The half-casing 9 has a bottom 10 with radial orientation and a peripheral rim 11 which extends axially from the outer edge of the bottom 10 to the outer skirt 5 of the bell 4.

[0042] The half-casing 9 and the bell 4 are fastened to each other by means of fasteners 12, such as fastener screws. The fasteners 12 pass through holes formed in mounting lugs 13, 14 which project radially from the outer skirt 5 of the bell 4 and from the peripheral rim 11 of the half-casing 9 and which are regularly distributed around the X-axis. The fastener screws are mounted in tapped holes formed in the mounting lugs 14 of the bell 4.

[0043] In order to guarantee the sealing of the housing space defined by the half-casing 9 and the bell 4, an annular sealing gasket 15 is interposed between the end of the external skirt 5 of the bell 4 and the end of the peripheral rim 11 of the half-casing 9.

[0044] The electric machine 1 comprises a stator 16 and two rotors, namely a front rotor 17 and a rear rotor 18, arranged axially on either side of the stator 16. The front rotor 17 and the rear rotor 18 are thus respectively arranged axially opposite the front face and the rear face of the stator 16. The stator 16 as well as the front rotor 17 and the rear rotor 18 are housed within the housing space defined by the half-casing 9 and the bell 4.

[0045] With reference to Figures 5 to 7, the stator 16 is described below. It comprises a plurality of teeth 19, one of which is shown in [Fig. 6]. Each tooth 19 is made in two parts 19a, 19b and has flanges 20, 21 at its two ends. In the embodiment shown, the two parts 19a, 19b of the tooth 19 are joined together by the assembly of one or more pins formed in one of the two parts 19a, 19b inside an orifice provided in the other of the two parts 19a, 19b. In an alternative not shown, each tooth 19 can be made in a single part, and in this case without the flange 20.

[0046] The teeth 19 are, for example, made by stacking sheets of electrical steel. Alternatively, each tooth 19 is made of soft magnetic composite material, or "Soft Magnetic Composite (SMC)", obtained in particular by sintering.

[0047] In the illustrated embodiment, each tooth 19 carries a coil 22. Each coil 22 has an insulating support 23 which has a sleeve fitted onto the tooth 19 and two flanges extending in vertical planes from each end of the sleeve. The coils 22 also have a winding 24 made of wire, for example copper, which is wound around the sleeve of the insulating support 23 between the two flanges. In this embodiment, the windings 24 are of the concentrated type, with one winding 24 per tooth 19.

[0048] In another embodiment, not shown, the windings 24 are of the distributed type, that is to say that each winding 24 is distributed over at least two of the teeth 19 of the stator 16.

[0049] Furthermore, the stator 16 includes a support structure 25, visible in particular in Figures 4 and 7, which has an annular shape. The support structure 25 is made of an electrically insulating material selected from polymer materials, such as fiber-reinforced polymer materials, particularly glass fibers. The polymers may be selected from polyamides, in particular long-chain polyphthalamides (e.g., PA9T GF30) and polyamides 6.6 (e.g., PA6.6 GF50), polyethersulfones (e.g., PESU-GF30), and polyphenylene sulfides (e.g., PPS GF40). The support structure 25 supports the teeth 19 of the stator 16.

[0050] The support structure 25 comprises two flanges, namely a front flange 26 and a rear flange 27, which are fixed to each other and together define a housing space for the teeth 19 and the coils 22.

[0051] Each of the front 26 and rear 27 flanges comprises a radially oriented side 28, an outer skirt 29, and an inner skirt 30. The outer skirt 29 of each of the front 26 and rear 27 flanges is fixed to the outer skirt 29 of the other of the front 26 and rear 27 flanges such that said outer skirts 29 define the outer periphery of the support structure 25. The inner skirt 30 of each of the front 26 and rear 27 flanges is fixed to the inner skirt 30 of the other of the front 26 and rear 27 flanges such that said inner skirts 30 define the inner periphery of the support structure 25.

[0052] As shown in [Fig. 7], the inner skirts 30 of the front 26 and rear 27 flanges are fastened to each other by fasteners 31, such as screws. To this end, the inner skirts 30 have flanges 32 at their ends, which are equipped with openings allowing the passage of the fasteners 31. Furthermore, the openings of one of the front 26 and rear 27 flanges, here those of the rear flange 27, have a thread for screwing in the fasteners 31. In one embodiment, the rear flange 27 has smooth openings and the fasteners 31 are self-drilling screws for plastic. In another embodiment, the threads are formed in an insert, for example metallic, which is overmolded with said rear flange 27.

[0053] Furthermore, the outer skirts 29 of the front 26 and rear 27 flanges are also fastened to each other by fasteners 33, such as screws, one of which is shown in [Fig. 2]. To this end, the outer skirts 29 have flanges 34 at their ends, which are equipped with openings allowing the passage of the fasteners 33. In addition, the fasteners 33 are received in a blind tapped bore 35 provided in the half-casing 9, and more particularly in its bottom 10. Thus, said fasteners 33 ensure both the fastening of the outer skirts 29 to each other and the fastening of the stator 16 to the half-casing 9.

[0054] Furthermore, as shown in [Fig. 5], the side 28 of each of the front 26 and rear 27 flanges has recesses 36 that receive the axial ends of the teeth 19 by means of a form fit. This ensures the positioning of the teeth 19 and the coils 22 around the X-axis when the front 26 and rear 27 flanges are fixed to each other. It also allows the teeth 19 to be axially held. The teeth 19 can be bonded to the sides.

[0055] Furthermore, the stator 16 also includes an interconnector 37, notably illustrated in [Fig. 5]. The interconnector 37 allows, on the one hand, the windings of the coils 22 to be connected to each other and, on the other hand, to be connected to a Connector 38, visible in [Fig. 4]. Connector 38 is housed in an opening in the half-casing 9 and is intended to be connected to the vehicle's electrical circuit. In the embodiment shown, the interconnector 37 is housed in a space in the rear flange 27 housing, which is radially formed between the side 28 and the outer skirt 29 of said rear flange 27. Furthermore, the interconnector 37 is radially positioned outside the rear rotor 18.

[0056] The interconnector 37 has four annular conductive traces corresponding to the neutral and the three phases of the electric machine 1. The conductive traces are embedded in a resin to electrically insulate them from one another. Furthermore, as shown for example in [Fig. 6], the interconnector 37 also has three connection tabs 39, each of which is connected to one of the conductive traces. The connection tabs 39 project radially outwards from the support structure 25 of the stator 16, in order to be connected to the connector 38.

[0057] As illustrated for example in [Fig.4], the front rotor 17 and the rear rotor 18 each have a support disc 40 which is rotationally coupled to the rotor shaft 8 of the electric machine 1. They further have a plurality of permanent magnets 41 which are fixed against the face of the support disc 40 which is opposite the stator 16, i.e. against the rear face of the support disc 40, for the front rotor 17, and against the front face of the support disc 40, for the rear rotor 18.

[0058] The rotor shaft 8 is guided in rotation on the half-case 9 and on the bell 4 of the reduction device 2 by means of a pair of roller bearings 42, 43. Thus, the support structure 25 of the stator 16 does not perform any function of guiding in rotation of the front rotor 17, the rear rotor 18 and the rotor shaft 8, which allows it to be made of a material that is less mechanically resistant and electrically insulating, such as a polymer material.

[0059] The pair of bearings comprises a front bearing 42 and a rear bearing 43. Each of the front bearing 42 and rear bearing 43 comprises an inner ring, an outer ring and rolling elements, for example balls, interposed between the inner ring and the outer ring.

[0060] As shown in [Fig. 2], the rear bearing 43 is interposed between the rotor shaft 8 and the bottom 10 of the housing 9. To achieve this, the rear bearing 43 is, on the one hand, fitted onto the rotor shaft 8 and bears forward against a shoulder 44 formed on the rotor shaft 8. On the other hand, the rear bearing 43 is fitted inside a housing 45 formed in the housing 9. The housing 45 is delimited by the bottom 10 of the housing 9 and by an annular skirt 46 which projects axially forward from the bottom 10 of the housing 9. The rear bearing 43 is held radially inside the annular skirt 46 and is supported against the bottom 10 of the half-casing 9.

[0061] As shown, for example, in [Fig. 2], the front roller bearing 42 is fitted onto a front portion of the rotor shaft 8. The front roller bearing 42 is designed to slide axially within a housing 47 formed in the bell housing 4 when the electric machine 1 and the reduction device 2 are fixed to each other. The front roller bearing 42 rests rearward against a shoulder 48 formed on the rotor shaft 8. The housing 47 that receives the front roller bearing 42 is delimited by the bottom wall 6 of the bell housing 4 and by an annular skirt 49. The annular skirt 49 projects axially rearward from the bottom wall 6 of the bell housing. The rear roller bearing 43 is held radially inside the annular skirt 49.In addition, in order to ensure axial support of the front bearing 42, a shim or spring washer, not shown, is fitted onto the rotor shaft 8 and interposed axially between the bottom wall 6 of the bell 4 and the front bearing 42.

[0062] In an alternative embodiment not shown, the front roller bearing 42 is not fitted onto the rotor shaft 8. In this case, the rotational guidance of the rotor shaft 8 is achieved via the input shaft of the reduction device 3 to which it is coupled. In other words, the front roller bearing 42 is fitted onto the input shaft of the reduction device 3. Another roller bearing also guides the rotation of the input shaft.

[0063] It is thus understood that the assembly comprising the electric machine 1 and the reduction device 4 includes, depending on the embodiment, three or four roller bearings for guiding the rotation of the rotor shaft and the input shaft of the reduction device 3. When the assembly includes three roller bearings, two are fitted onto one of the rotor and input shafts and only one onto the other. When it includes four roller bearings, each of the rotor and input shafts of the reduction device 3 is guided in rotation by a pair of roller bearings.

[0064] Furthermore, it can be seen in [Fig.2] that the support discs 40 have an external portion 50 in which the permanent magnets 41 are fixed and an internal coupling portion 51 which rotationally couples the support disc 40 to the rotor shaft 8.

[0065] The internal coupling portion 51 is equipped with a splined hub which is fitted onto a splined portion of the rotor shaft 8. The internal coupling portion 51 of the support discs 40 is further fixed axially on the rotor shaft 8. In the embodiment shown, the internal coupling portion 51 of each of the support discs 40 is axially locked between a central shoulder 52 formed in the rotor shaft 8 and a nut 53 which is mounted on a threaded portion of the rotor shaft 8.

[0066] In the advantageous embodiment shown, the outer portion 50 of the support discs 40 is positioned axially opposite the stator 16, while the inner coupling portion 51 is positioned radially inside the stator 16. In other words, the inner coupling portions 51 are axially offset relative to the outer portions 50: the inner coupling portion 51 of the front rotor 17 is axially offset rearward, while the inner coupling portion 51 of the rear rotor 18 is axially offset forward. As shown, for example, in [Fig. 2], the outer portion 50 of each support disc 40 is connected to the inner coupling portion 51 by a frustoconical portion 54.

[0067] Thanks to the aforementioned geometry of the support discs 40, the rear bearing 43 is, at least partially, positioned radially within the outer portion 50 of the rear rotor support disc 40. Similarly, the front bearing 42 is, at least partially, positioned radially within the outer portion 50 of the front rotor support disc 40. This arrangement thus makes it possible to limit the axial dimensions of the electric machine 1.

[0068] A cooling fluid circulation circuit for cooling the electric machine 1 will be described below. The cooling fluid is a dielectric fluid, such as oil. The circulation of such a cooling fluid is specifically intended to cool the stator coils 22 16 in order to prevent overheating of the electric machine 1.

[0069] As shown in [Fig. 1], the bell 4 of the reduction device 2 preferably has, near its highest point, a cooling fluid inlet 55. The inlet 55 here has the form of a fitting that is configured to be connected to a cooling fluid supply pipe.

[0070] The inlet 55 opens into a sealed annular chamber 56, visible in [Fig. 2], which is formed radially between the support structure 25 of the stator 16 and the bell 4 of the reduction device 2. To achieve this, as shown in Figures 3, 4, and 7, the outer skirt 29 of the front flange 26 carries two sealing O-rings 57, 58, each of which is mounted in a groove formed in said outer skirt 29. When the electric machine 1 and the reduction device 2 are assembled together, said sealing O-rings 57, 58 come into radial contact against the inside of the outer skirt 5 of the bell 4, thus defining said sealed annular chamber 56. Furthermore, the outer skirt 29 of the front flange 26 has a plurality of spray orifices 59, also visible in Figures 3, 4 and 7.The spray orifices 59 are regularly distributed around the X axis and open radially outside the coils 22 of the stator 16.

[0071] The bell 4 of the reduction device 2 also has a cooling fluid outlet 60, visible in [Fig. 2], preferably at its lowest point. The outlet 60 communicates with a channel 61 formed in the outer skirt 5 of the bell 4 and opening into the sealed annular chamber 56. The outlet 60 is intended to be connected to a cooling fluid drain pipe. The outlet 61 also has the form of a fitting, which is received in an opening provided in the bottom wall 6 of the bell 4.

[0072] Thus, during operation, the cooling fluid is conducted into the sealed annular chamber 60 via the fluid inlet 55. It is then sprayed onto the coils 22 through the spray orifices 59 provided in the outer skirt of the front flange 26. The cooling fluid then falls, by gravity, through the spray orifices 59, into a lower area of ​​the sealed annular chamber 60 from which it can be discharged through the outlet 60 via the channel 61.

[0073] Although the invention has been described in connection with several particular embodiments, it is clearly evident that it is by no means limited to them and that it includes all technical equivalents of the means described as well as their combinations if these fall within the scope of the invention, as defined by the claims.

[0074] The use of the verb "comprise", "comprendre" or "include" and its conjugated forms does not exclude the presence of other elements or other steps than those stated in a claim.

[0075] In the claims, any reference sign in parentheses shall not be interpreted as a limitation of the claim.

Claims

Demands

1. An electric machine (1) intended to be fixed to the rear of a reduction device (2) and comprising: - a stator (16) comprising a support structure (25) having an annular shape centered around an axis X, a plurality of teeth (19) distributed around the axis X and supported by the support structure (25) and coils (22) which comprise a winding (24) and which are carried by the teeth (19); - a rear rotor (18) and a front rotor (17) which are arranged axially on either side of the stator (16) and which are rotationally fixed to a rotor shaft (8) movable in rotation about the axis X, said rotor shaft (8) passing through the support structure (25) and comprising a front portion which is intended to be coupled to a gear system of the reduction device (2);and - a half-casing (9) intended to be fixed to a bell (4) of the reduction device (2) and configured to form with said bell (4) a housing space in which the stator (16), the front rotor (17) and the rear rotor (18) are housed; the support structure (25) being fixed to said half-casing (9); said electrical machine (1) being characterized in that: - it comprises a rear roller bearing (43) interposed between a rear portion of the rotor shaft (8) and the half-casing (9); - the front portion of the rotor shaft (8) is intended to be guided in rotation by a front roller bearing (42) intended to be carried by the reduction device (2); and - the support structure (25) is made of an electrically insulating material.

2. Electric machine (1) according to claim 1, wherein the support structure (25) is made of a polymer material.

3. Electric machine (1) according to claim 1 or 2, wherein the front bearing support (42) is fitted onto the front portion of the rotor shaft (8) and is intended to be arranged radially inside a housing (47) formed in the bell (4).

4. Electric machine (1) according to any one of claims 1 to 3, wherein the support structure (25) comprises a front flange (26) and a rear flange (27) which are fixed to each other and between which the teeth (19) of the stator (16) are held.

5. Electric machine according to claim 4, in which each of the front (26) and rear (27) flanges has a side (28) having a radial orientation, said side (28) having impressions (36) each receiving by form fitting an axial end of one of the teeth (19).

6. Electric machine (1) according to any one of claims 1 to 5, wherein the support structure (25) has an inner periphery which is spaced from the rotor shaft (8) by a radial space which is devoid of a bearing.

7. An electric machine (1) according to any one of claims 1 to 6, in which the support structure (25) has an outer periphery which carries two sealing O-rings (57, 58) intended to cooperate with the bell (4) of the reduction device (2) so as to provide between said outer periphery and the bell (4), a sealed annular chamber (56) intended to receive a cooling fluid, the outer periphery further having a plurality of spray orifices (59) which are distributed circumferentially around the axis X and which open radially opposite the coils (22) of the stator (16).

8. Electric machine (1) according to any one of claims 1 to 7, wherein the rear rotor (18) comprises a support disc (40) including an outer portion (50) and an inner coupling portion (51), the outer portion (50) carrying a plurality of permanent magnets (41) distributed around the X axis and being positioned axially opposite the stator (16), the inner coupling portion (51) being rotationally coupled to the rotor shaft (8) and being offset forward relative to the outer portion (50), the rear bearing support (43) being arranged radially inside the outer portion (50).

9. Electric machine (1) according to any one of claims 1 to 8, wherein the front rotor (17) comprises a support disc (40) including an outer portion (50) and an inner coupling portion (51), the outer portion (50) carrying a plurality of permanent magnets (41) distributed around the X axis and being positioned axially opposite the stator (16), the inner coupling portion (51) being rotationally coupled to the rotor shaft (8) and being offset rearward relative to the outer portion (50).

10. Electric machine (1) according to claim 9 taken in combination with claim 3, wherein the front bearing (42) is arranged radially inside the outer portion (50) of the support disc (40) of the front rotor (17).

11. Assembly comprising an electric machine (1) according to any one of claims 1 to 10 and a reduction device (2) comprising a bell (4) which is fixed to the half-casing (9) of the electric machine (1) and which defines with the half-casing the housing space in which the stator (16), the front rotor (17) and the rear rotor (18) are housed.

12. Assembly comprising an electric machine (1) according to claim 7 and a reduction device (2) comprising a bell (4) which is fixed to the half-casing (9) of the electric machine (1) and which defines with the half-casing (9) the housing space in which the stator (16), the front rotor (17) and the rear rotor (18) are housed, the bell (4) having a cooling fluid inlet (55) which opens into the sealed annular chamber (56) and a cooling fluid outlet (60) which is in fluidic communication with the sealed annular chamber (56).

Images