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 housing (3) defining a compartment and having a front end (14); - at least one rotor (4) fixed in rotation to an output shaft (7); and - at least one stator (5, 6) which is positioned in the compartment, axially opposite the rotor (4); the front end (14) of the housing (3) being intended to be inserted inside a bell (20) of the reduction device (2) and being arranged to form, with said bell (20), a chamber (23) intended to receive a cooling fluid;the casing (3) comprising a plurality of conduits (46) which pass through the front bottom (14) and are thus intended to open into the chamber (23), the conduits (46) projecting rearward from the front bottom (14) and comprising at least one spray orifice (47, 48) which is directed radially inward opposite one of the coils (38) of the stator (5, 6). Figure for the abbreviation: 2;

Description

Title of the invention: Axial flux rotating electric machine Technical field

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

[0002] In the state of the art, axial flux rotating electrical machines are known which are equipped with a cooling circuit in which a cooling fluid circulates and which aims to cool the rotating machine in order to prevent it from heating up. Such a rotating machine is disclosed in particular in documents FR3073341 and FR3117706.

[0003] Such axial flux rotating electrical machines are not fully satisfactory, in particular in that their cooling circuit does not ensure sufficiently efficient and homogeneous cooling of the stator coils and / or has a complex structure. Summary of the invention

[0004] An idea underlying the invention is to propose an axial flux rotating electrical machine which is simple, compact and equipped with efficient cooling means.

[0005] Another idea underlying the invention consists of proposing an axial flux rotating electrical machine in which the viscous friction losses of the rotor are limited.

[0006] According to one embodiment, the invention provides an electrical machine intended to be fixed to the rear of a reduction device and comprising: - a casing defining a housing and comprising a front bottom having an opening; - at least one rotor mounted to rotate in the housing of the casing around an axis X, said rotor being integral in rotation with an output shaft comprising a front end which is intended to be coupled to a gear system of the reduction device and which passes through the opening of the front bottom; and - at least one stator which is positioned in the housing, axially opposite the rotor, and comprises a stator body equipped with teeth which project towards the rotor and which are distributed around the X axis and coils which comprise a winding and which are carried by the teeth; the front bottom of the casing being intended to be inserted inside a bell of the reduction device and being arranged to form with said bell a chamber intended to receive a cooling fluid; the casing comprising a plurality of conduits which pass through the front bottom and which are thus intended to open into the chamber, the conduits projecting rearward from the front bottom and comprising at least one spray orifice which is directed radially inward opposite one of the coils of the stator.

[0007] Thanks to these characteristics, the structure of the electric machine is particularly simple and space-saving, in particular in that the chamber intended to receive the cooling fluid is formed between the front bottom of the casing and the bell of the reduction device.

[0008] According to embodiments, such an electrical machine may comprise one or more of the following characteristics.

[0009] According to one embodiment, the windings of the coils are concentrated, that is to say that the winding of each of the coils is mounted around one of the teeth. In other words, each tooth of the stator carries exactly one of the windings.

[0010] According to another embodiment, the windings of the coils are distributed, that is to say that each winding is distributed over at least two of the teeth of the stator.

[0011] According to one embodiment, the front bottom of the casing comprises a skirt which projects axially forward, said skirt having a groove in which an annular seal is mounted, said annular seal being intended to cooperate with a cylindrical wall formed in a bottom wall of the bell so as to ensure sealing of the chamber.

[0012] According to other embodiments, the sealing between the front bottom of the casing and the bottom wall of the bell can also be achieved by any other means. This can in particular be welding, for example by friction, ultrasound, laser or infrared, or bonding between, on the one hand, the skirt of the front bottom of the casing and, on the other hand, the cylindrical wall formed in the bottom wall of the bell.

[0013] According to one embodiment, in projection in a radial plane orthogonal to the X axis, the skirt is arranged radially inside the front stator. Thus, the chamber extends radially inward beyond the coils of the front stator, which increases the heat exchange by conduction between the cooling fluid received in the chamber and the front stator through the front end wall.

[0014] According to one embodiment, the electrical machine comprises a front stator and a rear stator which are positioned in the housing and are respectively arranged axially in front of and behind the rotor.

[0015] According to one embodiment, the ducts each comprise two spray orifices which are respectively directed radially inwards opposite one of the coils of the front stator and opposite one of the coils of the rear stator. Thus, a single cooling circuit is used to cool the two stators, which allows to further simplify the structure of the electric machine.

[0016] According to one embodiment, each of the front and rear stators comprises n coils (with n an integer) and the casing comprises n conduits, each conduit being arranged radially outside a respective coil of each of the stators.

[0017] According to one embodiment, the casing comprises a front half-casing and a rear half-casing which are fixed to each other, the front half-casing comprising the front bottom and a peripheral rim and the rear half-casing comprising a rear bottom and a peripheral rim, the front stator and the rear stator being respectively housed inside the front half-casing and the rear half-casing.

[0018] According to one embodiment, the electrical machine comprises a front flange and a rear flange which are respectively interposed axially between the front stator and the rotor and between the rear stator and the rotor, the front flange being fixed in a sealed manner to the front bottom of the front half-casing in a zone situated radially inside the front stator, the rear flange being fixed in a sealed manner to the rear bottom of the rear half-casing in a zone situated radially inside the rear stator and being fixed in a sealed manner to the front flange in a zone situated radially outside the rotor.

[0019] Thus, such an arrangement makes it possible to encapsulate the rotor in a simple manner in order to prevent it from being in contact with the cooling fluid. This avoids friction losses which would be likely to be caused by the viscous friction of the rotor with the cooling fluid.

[0020] According to one embodiment, the front flange and the rear flange are made of plastic.

[0021] According to one embodiment, the front flange comprises an internal skirt which is positioned radially inside the front stator, the front end comprising an annular sealing portion projecting axially towards the rear, an annular seal being arranged radially between the internal skirt of the front flange and the annular sealing portion of the front end.

[0022] According to other embodiments, the sealing between the front flange and the front bottom of the casing can also be achieved by any other means. This can in particular be welding, for example by friction, ultrasound, laser or infrared, or bonding between, on the one hand, the internal skirt of the front flange and, on the other hand, the annular sealing portion of the front bottom.

[0023] According to one embodiment, the rear end plate comprises an internal skirt which is positioned radially inside the rear stator, the rear end plate comprising an annular sealing portion projecting axially forward, an annular seal being arranged radially between the internal skirt of the rear end plate and the annular sealing portion of the rear end plate.

[0024] According to other embodiments, the sealing between the rear flange and the rear bottom of the casing can also be achieved by any other means. This can in particular be welding, for example by friction, ultrasound, laser or infrared, or bonding between, on the one hand, the internal skirt of the rear flange and, on the other hand, the annular sealing portion of the rear bottom.

[0025] According to one embodiment, an annular seal is interposed between the rear flange and the front flange.

[0026] According to other embodiments, the sealing between the rear flange and the front flange can also be achieved by any other means. This can in particular be welding, for example by friction, ultrasound, laser or infrared, or gluing.

[0027] According to one embodiment, the front flange comprises a front face having a plurality of recesses each receiving one end of one of the teeth of the front stator and / or in which the rear flange comprises a rear face having a plurality of recesses each receiving one end of one of the teeth of the rear stator. This makes it possible to limit the thickness of the air gap between the coils of the stators and the magnets of the rotor.

[0028] According to one embodiment, the electrical machine comprises an interconnector comprising an interconnector support, conductive traces arranged inside the interconnector support and connection lugs which are each connected to one of the conductive traces, to one end of a winding of one of the coils of the rear stator and to one end of a winding of one of the coils of the front stator. Thus, a single interconnector is used for both stators, which makes it possible to further simplify the electrical machine.

[0029] According to one embodiment, the interconnector support is arranged radially between the coils of the rear stator and the rear half-casing and the connection tabs project axially forward from the interconnector support. Thus, the interconnector support can be arranged on the same diameter as the conduits, which makes it possible to limit the radial size of the electrical machine.

[0030] According to one embodiment, the front half-casing has a plurality of holes allowing in particular the cooling fluid to be evacuated towards a cooling fluid outlet.

[0031] According to one embodiment, the front half-casing has an end portion which is folded radially outwards and which has a plurality of holes through which the connection tabs of the interconnector and the ends of the windings of the coils of the front stator pass.

[0032] According to one embodiment, the output shaft is guided in rotation around the X axis by means of at least one rolling bearing, the front bottom having an annular skirt which borders said opening and extends axially towards the rear, said rolling bearing bearing being received inside said annular skirt.

[0033] According to one embodiment, the invention also provides an assembly comprising a aforementioned electrical machine and a housing of a reduction device; the housing comprising a main enclosure intended to house a gear system and a bell which projects rearwardly from the main enclosure and covers the front bottom of the casing, the bell forming with the front bottom of the casing a chamber intended to receive a cooling fluid.

[0034] According to embodiments, such an assembly may comprise one or more of the following characteristics.

[0035] According to one embodiment, the bell comprises a cooling fluid inlet which opens into the chamber and a cooling fluid outlet which opens into the casing.

[0036] According to one embodiment, the inlet has the shape of a connector end piece configured to be connected to a cooling fluid supply pipe.

[0037] According to one embodiment, the bottom wall of the bell has an external annular portion which projects radially outwards relative to the main enclosure of the housing, an orifice receiving the connecting end piece forming the inlet being provided in said external annular portion. This makes it possible to limit the radial size of the assembly.

[0038] According to one embodiment, the outlet has the shape of a connector end piece configured to be connected to a cooling fluid discharge pipe.

[0039] According to one embodiment, the bottom wall of the bell has an external annular portion which projects radially outwards relative to the main enclosure of the housing, an orifice receiving the connecting end piece forming the outlet being provided in said external annular portion. This makes it possible to limit the radial size of the assembly.

[0040] According to one embodiment, the bell comprises a bottom wall and a skirt which projects axially rearward from the bottom wall and is arranged radially outside the casing, an annular seal being compressed between the skirt of the bell and the casing. Brief description of the figures

[0041] The invention will be better understood, and other aims, details, characteristics and advantages thereof will appear more clearly during the following description of several particular embodiments of the invention, given solely for illustrative and non-limiting purposes, with reference to the appended drawings.

[0042] [Fig-1] [Fig. 1] is a perspective view of an assembly comprising a machine electric and a reduction device fixed to each other.

[0043] [Fig.2] [Fig.2] is a partial view of the whole of [Fig.l], in section along an axial plane.

[0044] [Fig.3] [Fig.3] is a perspective view of the housing of the reduction device.

[0045] [Fig.4] [Fig.4] is a perspective view of the front half-crankcase.

[0046] [Fig.5] [Fig.5] is an exploded view showing the front half-casing, the stator front and the front flange.

[0047] [Fig.6] [Fig.6] is an exploded view showing the rear half-crankcase, the rear stator and the rear end plate.

[0048] [Fig.7] [Fig.7] is a partial perspective view of the electrical machine in which the front casing is not shown so as to observe in particular the front stator.

[0049] [Fig.8] [Fig.8] is a partial perspective view of the electrical machine in which neither the front casing nor the front stator are shown so as to observe the front face of the front flange. Description of the embodiments

[0050] In the description and the claims, the terms "external" and "internal" as well as the orientations "axial" and "radial" will be used to designate, according to the definitions given in the description, elements of the electrical machine. By convention, the axis X of rotation of the rotor 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 qualified as internal as opposed to an external element located radially on the periphery. The "circumferential" orientation is directed orthogonally to the X axis and orthogonally to the radial direction. 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 arranged 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.

[0051] In the example described below, the electrical machine 1 is a permanent magnet synchronous machine. It can in particular be used as a motor intended to provide propulsion for an electric or hybrid vehicle and / or as a generator for such a vehicle.

[0052] In relation to figures 1 to 7, an assembly is described below comprising an electrical machine 1, rotating with axial flux, and a reduction device 2 associated with said electrical machine 1.

[0053] As shown for example in Figures 1 and 2, the electric machine 1 comprises a casing 3 defining a housing in which are housed at least one rotor 4 mounted to rotate around the axis of X and at least one stator 5, 6 which is placed axially face to face with one of the two faces of the rotor 4.

[0054] In the embodiment shown, the electrical machine 1 comprises a single rotor 4 and two stators, namely a front stator 5 and a rear stator 6, which are positioned axially on either side of the rotor 4 and which are thus respectively arranged axially opposite each other of the two faces of the rotor 4.

[0055] The rotor 4 is integral in rotation with an output shaft 7, notably visible in [Fig. 2]. The output shaft 7 has a splined end 8 which is intended to be housed in a splined hub 9, also illustrated in [Fig. 2], of a reduction device 2.

[0056] The reduction device 2 comprises a gear system, not shown, making it possible to increase the torque delivered by the electric machine 1 towards 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.

[0057] The casing 3 comprises two half-casings, namely a front half-casing 10 and a rear half-casing 11, which are fixed to each other and define the housing in which the rotor 4 and the stators 5, 6 are housed. Each half-casing 10, 11 comprises a peripheral rim 12, 13 which extends axially and a bottom 14, 15 which extends radially from one end of said peripheral rim 12, 13. The bottom 14 of the front half-casing 10 will hereinafter be referred to as the “front bottom” and that of the rear half-casing 11 as the “rear bottom”.

[0058] The peripheral rim 12, 13 of each half-casing 10, 11 extends to the peripheral rim 12, 13 of the other half-casing 10, 11. The two half-casings 10, 11 are fixed to each other by means of fixing members 16, such as bolts. The fixing members 16 pass through fixing lugs 17 which project radially from the peripheral rims 12, 13 of the half-casings 10, 11 and are regularly distributed around the axis X.

[0059] Furthermore, the reduction device 2 comprises a housing 18 which is configured to be fixed to the casing 3 of the electric machine 1, opposite the front bottom 14.

[0060] As shown in particular in [Fig.3], the housing 18 of the reduction device 2 comprises a main enclosure 19 in which the gear system, not shown, is housed, and a bell 20 which projects from the main enclosure 19, in the direction of the electric machine 1. The bell 20 is intended to cover the front half-casing 10 of the electric machine 1 and to be fixed to the casing 3. It comprises a skirt 22 and a bottom wall 21 separating the interior of the main enclosure 19 from the interior of the bell 20.

[0061] As shown in [Fig.2], when the housing 18 of the reduction device 2 is fixed to the casing 3 of the electric machine 1, the bell 20 forms with the front bottom 14 a sealed chamber 23, intended to receive a cooling fluid. The front bottom 14 of the front half-casing 10 comprises a skirt 24 projecting axially forward, that is to say towards the bottom wall 21 of the bell 20. The skirt 24 has an external surface equipped with a groove 25 in which an annular seal 26 is housed. When the reduction device 2 and the electrical machine 1 are fixed to each other, the skirt 24 is received in a recess 27 formed in the bottom wall 21 of the bell 20. The recess 27 is defined radially by an external cylindrical wall 28. The annular seal 26 is compressed between the skirt 24 and the external cylindrical wall 28 of the recess 27 in order to ensure the sealing of the radially internal edge of the chamber 23. In projection in a radial plane orthogonal to the axis X, the skirt 24 is arranged radially inside of the front stator 5.Thus, the chamber 23 extends radially inwardly beyond the front stator 5, which increases the heat exchange by conduction between the cooling fluid and the front stator 5 through the front bottom 14.

[0062] The skirt 22 of the bell 20 is arranged radially outside the peripheral rim 12 of the front half-casing 10. The skirt 22 of the bell 20 is fixed to the casing 3 by means of fixing members 29, such as screws. In the embodiment shown, the fixing members 29 pass through fixing lugs 30 which project radially outwards from the skirt 22 of the bell 20 and from the peripheral rim 12 of one of the half-casings 10, 11. The bell 22 can be fixed to the front half-casing 10 or to the rear half-casing 11. These two variants correspond respectively to FIGS. 1, 4, 7 and 8, on the one hand, and to FIGS. 2, 5 and 6 on the other hand.

[0063] As illustrated in Figures 2 and 3, the skirt 22 of the bell 20 comprises a front part 31 and a rear part 32 having a diameter greater than that of the front part 31. The front part 31 has an internal surface equipped with a groove in which an annular seal 33 is housed. The annular seal 33 is compressed between the peripheral rim 12 of the front half-casing 10 and the front portion 31 of the skirt 22 in order to ensure the sealing of the radially external edge of the chamber 23.

[0064] As shown in Figures 1 and 2, the bell 20 of the reduction device 2 has a cooling fluid inlet which opens into the chamber 23. The inlet here has the shape of a connecting end piece 34 configured to be connected to a cooling fluid supply pipe. In the embodiment shown, the bottom wall 21 of the bell 20 has an external annular portion which projects radially outwards relative to the main enclosure 19 of the housing 18 and in which an orifice is formed receiving the connecting end piece 34. Thus, the connecting end piece 34 is oriented axially, towards the front, and is arranged radially outside the main enclosure 19 of the housing 18. This makes it possible to limit the radial size of the assembly.

[0065] The housing 18 of the reduction device 2 also comprises a cooling fluid outlet which is arranged radially outside the chamber 23 and which communicates with the casing 3, preferably at its low point, through holes 44 arranged in the front half-casing 10 which will be described in more detail later. The outlet is intended to be connected to a cooling fluid discharge pipe. In the embodiment shown, the outlet also has the shape of a connecting end piece 35, which is received in an orifice arranged in the external annular portion of the bottom wall 21. This connecting end piece 35 is also oriented axially towards the front and is arranged radially outside the main enclosure 19 of the housing 18.

[0066] In relation to [Fig. 5], one of the stators 5, 6 of the electrical machine 1 is now described, namely the front stator 5, that is to say the one which is housed inside the front half-casing 10. The front stator 5 comprises a stator body which comprises an annular plate 36, centered around the axis X, and teeth 37 which are distributed on one face of the annular plate 36 and project axially in the direction of the rotor 4, that is to say towards the rear.

[0067] According to one embodiment, the teeth 37 are made by a stack of electrical steel sheets. Alternatively, each tooth 37 is made of soft magnetic composite material, or "Soft Magnetic Composite (SMC)" in English, in particular obtained by sintering.

[0068] The front stator 5 also comprises a plurality of coils 38 which are each carried by one of the teeth 37. Each coil 38 comprises an insulating support 39 which comprises a sheath fitted onto one of the teeth 37 and two rims extending in vertical planes, respectively from one and the other of the two ends of the sheath.

[0069] The coils 38 also comprise a winding 40 which is made of wire, for example copper, and is wound around the sheath of the insulating support 39 between the two edges. The coils 38 are arranged circumferentially next to each other, leaving a space between two adjacent coils 38.

[0070] In the embodiment shown, the windings are of the concentrated type with one winding 33 per tooth 26. In another embodiment, not shown, the windings are of the distributed type.

[0071] As shown in [Fig.6], the rear stator 6 has a structure similar to that of the front stator 5.

[0072] The electrical machine 1 also comprises an interconnector 41, visible in figures 2, 6, 7 and 8. The interconnector 41 makes it possible, on the one hand, to connect the windings 40 of the coils 37 to each other and, on the other hand, to connect them to a connector 45, visible in [Fig.2], which is intended to be connected to the electrical circuit of the vehicle. In the embodiment shown, the interconnector 41 is housed inside the rear half-casing 11 and is positioned radially between the rear stator 6 and the peripheral rim 13 of the rear half-casing 11.

[0073] The interconnector 41 comprises an interconnector support 42 which is annular in shape. The interconnector 41 also comprises three annular conductive traces corresponding to the three phases of the electrical machine 1 which are housed inside the interconnector support 42. The conductive traces are embedded in a resin allowing them to be electrically insulated from each other. Furthermore, the interconnector 41 comprises connection tabs 43 which are each connected to one of the conductive traces and which project axially forward from the interconnector support 42.

[0074] As illustrated in Figures 4 and 5, the peripheral rim 12 of the front half-casing 10 has an end portion which is folded radially outwards and which has a plurality of holes 44 allowing the circulation of the cooling fluid towards the outlet. The connection tabs 43 of the interconnector 41 pass through said holes 44. The end of the connection tabs 43 is thus located radially outside the front half-casing 10, radially between the peripheral rim 12 of the front half-casing 10 and the skirt 22 of the bell 20. Furthermore, the ends of the windings 40 of the coils 37 of the front stator 5 extend radially outwards so as to pass through said holes 44. Thus, the ends of the windings are welded to the connection tabs 43. The ends of the windings of the coils 37 of the rear stator 6 extend radially outwards and are also welded to the connection tabs 43.

[0075] The front half-casing 10 comprises a plurality of ducts 46, notably visible in FIGS. 2, 4 and 5, which are regularly distributed around the axis X and which each open into the chamber 23 formed between the front half-casing 10 and the bell 20. Each of the ducts 46 projects axially rearward from the front bottom 14. The ducts 46 have an end which is located radially outside one of the coils 37 of the rear stator 6. In addition, the ducts 46 each have at least two spray orifices 47, 48 which are directed radially inward and are respectively arranged opposite one of the coils 37 of the front stator 5 and one of the coils 37 of the rear stator 6. The ducts 46 thus make it possible to conduct the cooling fluid from the chamber 23 towards the front stator 5 and rear stator 6.

[0076] Advantageously, in order to ensure uniform cooling of the coils 37, the front half-casing 10 comprises as many conduits 46 as each stator 5, 6 comprises coils 37 so that each of the coils 37 is located opposite one spray orifices 47, 48.

[0077] Furthermore, the electrical machine 1 advantageously comprises two flanges, namely a front flange 49, shown in particular in Figures 2 and 5, and a rear flange 50, shown in particular in Figures 2 and 6. The front flange 49 and the rear flange 50 are each interposed axially between one of the stators 4, 5 and the rotor 4. The flanges 49, 50 are intended to form a sealed barrier around the rotor 4 so that the area in which the rotor 4 is housed is free of cooling fluid. This makes it possible to limit the efficiency losses of the electrical machine 1 likely to be caused by the viscous friction of the rotor 4 with the cooling fluid. The flanges 49, 50 are, for example, made of plastic.

[0078] The front flange 49 is fixed in a sealed manner to the front end plate 14 in an area located radially between the coils 37 of the front stator 5 and the output shaft 7 while the rear flange 50 is fixed in a sealed manner to the rear end plate 15 in an area located radially between the coils 37 of the rear stator 6 and the output shaft 7. Furthermore, the front flange 49 and the rear flange 50 are fixed in a sealed manner to each other radially outside the rotor 4.

[0079] In the embodiment shown, each of the front 49 and rear 50 flanges comprises an internal skirt 51, 52 which is positioned, on the one hand, radially inside the coils 37 of one of the stators 5, 6 and, on the other hand, radially outside an annular sealing portion 53, 54 which is formed in the bottom 14, 15 of one of the half-casings 10, 11. The annular sealing portion 53, 54 comprises a groove in which an annular seal 55, 56 is housed, visible in [Fig. 2]. Each annular seal 55, 56 is thus compressed between the internal skirt 51, 52 of one of the flanges 49, 50 and the annular sealing portion 53, 54. Furthermore, each of the front 49 and rear 50 flanges also comprises a fixing portion 57, 58 which projects radially inwards from the internal skirt 51, 52.The fixing portion 57, 58 bears against the bottom 14, 15 of one of the half-casings 10, 11 and has orifices allowing the passage of fixing members 59, 60, such as fixing screws. The fixing members 59, 60 are received in threaded bores formed in the bottom 14, 15 of said half-casing 10, 11. In addition, an annular seal 62 is also interposed between the two flanges 49, 50.

[0080] Advantageously, in order to limit the axial thickness of the air gap between the coils 37 and the magnets of the rotor 4, the flanges 49, 50 have recesses 61, illustrated in [Fig. 8], which each receive the end of a tooth 37.

[0081] Returning to [Fig. 2], it can be seen that the rotor 4 comprises a disc which is secured to the output shaft 7 and has an orifice through which said output shaft 7 passes. The disc carries a plurality of permanent magnets which are distributed around the axis X. The permanent magnets have the shape of a truncated disc sector. They are each arranged in a slot on the disc.

[0082] The front bottom 14 is pierced in its center so as to form an opening allowing the passage of the output shaft 7 so that its splined end 8 can cooperate with the splined hub 9 of the reduction device 2. The output shaft 7 is guided in rotation, around the axis X, on the casing 3 by means of the two rolling bearings. The two rolling bearings are respectively carried by the front half-casing 10 and by the rear half-casing 11. The two rolling bearings are more particularly fitted inside annular skirts formed in the front bottom and the rear bottom.

[0083] The circulation of the cooling fluid inside the electrical machine 1, as described above, will now be described below. The cooling fluid is a dielectric fluid, such as oil for example. The circulation of such a cooling fluid aims more particularly to cool the coils 37 of the stators 5, 6 in order to avoid overheating of the electrical machine 1.

[0084] The cooling fluid is conducted into the chamber 23 via the fluid inlet. It is then sprayed onto each of the coils 37 via the spray orifices 47, 48 provided in the conduits 46. The cooling fluid then falls, by gravity, passing through the holes 44 of the front half-casing 10, into a lower zone of the casing 3 from which it can be evacuated via the fluid outlet.

[0085] Although the invention has been described in connection with several particular embodiments, it is quite obvious that it is in no way limited thereto and that it includes all the 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.

[0086] The use of the verb "comprise", "comprise" or "include" and its conjugated forms does not exclude the presence of other elements or other steps than those set out in a claim.

[0087] In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

Claims

Claims

1. Electrical machine (1) intended to be fixed to the rear of a reduction device (2) and comprising: - a casing (3) defining a housing and comprising a front end (14) having an opening; - at least one rotor (4) mounted to rotate in the housing of the casing (3) about an axis X, said rotor (4) being integral in rotation with an output shaft (7) having a front end which is intended to be coupled to a gear system of the reduction device (2) and which passes through the opening of the front end (14); and - at least one stator (5, 6) which is positioned in the housing, axially opposite the rotor (4), and comprises a stator body equipped with teeth (37) which project towards the rotor (4) and which are distributed about the axis X and coils (38) which comprise a winding (40) and are carried by the teeth (37);the front bottom (14) of the casing (3) being intended to be inserted inside a bell (20) of the reduction device (2) and being arranged to form, with said bell (20), a chamber (23) intended to receive a cooling fluid; the casing (3) comprising a plurality of conduits (46) which pass through the front bottom (14) and which are thus intended to open into the chamber (23), the conduits (46) projecting rearward from the front bottom (14) and comprising at least one spray orifice (47, 48) which is directed radially inward opposite one of the coils (38) of the stator (5, 6).;

2. Electrical machine (1) according to claim 1, in which the front bottom (14) of the casing (3) comprises a skirt (24) which projects axially forward, said skirt (24) having a groove (25) in which an annular seal (26) is mounted, said annular seal (26) being intended to cooperate with a cylindrical wall (28) formed in a bottom wall (21) of the bell (20) so as to ensure sealing of the chamber (23).

3. Electrical machine (1) according to claim 2, in which, in projection in a radial plane orthogonal to the X axis, the skirt (24) is arranged radially inside the stator (5, 6).

4. An electrical machine (1) according to any one of claims 1 to 3, comprising a front stator (5) and a rear stator (6) which are po- located in the housing and are respectively arranged axially in front of and behind the rotor (4).

5. Electrical machine (1) according to claim 4, in which the conduits (46) each comprise two spray orifices (47, 48) which are respectively directed radially inwards opposite one of the coils (38) of the front stator (5) and opposite one of the coils (38) of the rear stator (6).

6. An electrical machine (1) according to claim 4 or 5, wherein the casing (3) comprises a front half-casing (10) and a rear half-casing (11) which are fixed to each other, the front half-casing (10) comprising the front bottom (14) and a peripheral rim (12) and the rear half-casing (11) comprising a rear bottom (15) and a peripheral rim (13), the front stator (5) and the rear stator (6) being respectively housed inside the front half-casing (10) and the rear half-casing (11).

7. An electrical machine (1) according to claim 6, comprising a front flange (49) and a rear flange (50) which are respectively interposed axially between the front stator (5) and the rotor (4) and between the rear stator (6) and the rotor (4), the front flange (49) being fixed in a sealed manner to the front bottom (14) of the front half-casing (10) in an area situated radially inside the front stator (5), the rear flange (50) being fixed in a sealed manner to the rear bottom (15) of the rear half-casing (11) in an area situated radially inside the rear stator (6) and being fixed in a sealed manner to the front flange (49) in an area situated radially outside the rotor (4).

8. Electrical machine (1) according to claim 7, in which the front flange (49) comprises a front face having a plurality of recesses (61) each receiving one end of one of the teeth (37) of the front stator (5) and / or in which the rear flange (50) comprises a rear face having a plurality of recesses (61) each receiving one end of one of the teeth (37) of the rear stator (6).

9. An electrical machine (1) according to any one of claims 4 to 8, comprising an interconnector (41) comprising an interconnector support (42) which is arranged radially between the coils (38) of the rear stator (6) and the rear half-casing (11), conductive traces arranged inside the interconnector support (42) and connection tabs (43) which are each connected to one of the conductive traces, project axially forward from the interconnector support (42) and are each connected to one end of a winding (40) of one of the coils (38) of the rear stator (6) and at one end of a winding (40) of one of the coils (38) of the front stator (5).

10. An electrical machine (1) according to claim 9, wherein the front half-casing (10) has an end portion which is folded radially outwards and which has a plurality of holes (44) through which pass the connection tabs (43) of the interconnector (41) and the ends of the windings (40) of the coils (38) of the front stator (5).

11. An assembly comprising an electrical machine (1) according to any one of claims 1 to 10 and a housing (18) of a reduction device (2); the housing (18) comprising a main enclosure (19) intended to house a gear system and a bell (20) which projects rearwardly from the main enclosure (19) and covers the front bottom (14) of the casing (3), the bell (20) forming with the front bottom (14) of the casing (3) a chamber (23) intended to receive a cooling fluid.

12. An assembly according to claim 11, wherein the bell (20) has a cooling fluid inlet (34) which opens into the chamber (23) and a cooling fluid outlet (35) which opens into the casing (3).

13. An assembly according to claim 11 or 12, wherein the bell (20) comprises a bottom wall (21) and a skirt (22) which projects radially rearwardly from the bottom wall (21) and is arranged radially outside the casing (3), an annular seal (33) being compressed between the skirt (22) of the bell (20) and the casing (3).

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