WINDED ROTOR FOR AN ELECTRIC MOTOR WITH COOLING CIRCUIT

Description

[0001] The invention relates to a wound rotor for an electric motor arranged to allow for improved dissipation of the heat generated during its operation. The invention also relates to an electric motor comprising such a wound rotor.

[0002] In general, modern electric motors consist of a rotor attached to a shaft and a stator surrounding the rotor. The stator is mounted in a housing containing bearings for the shaft's rotation. The stator typically has a body made of stacked laminations forming a ring, the inner face of which has teeth that define pairs of slots opening inwards towards the stator body. These slots are designed to receive phase windings. These phase windings pass through the slots in the stator body and form coils that protrude from either side of the stator body. The phase windings can, for example, consist of a plurality of U-shaped conductor segments, with the free ends of two adjacent segments joined together by welding. The rotor can be of several types.One possible configuration consists of a wound rotor made up of a bundle of laminations mounted coaxially on the rotor shaft, said bundle of laminations having several pairs of poles, each pole being separated from an adjacent pole by an interpole space, and windings surrounding the poles of the bundle of laminations and being connected to a commutator generally formed by copper rings coming opposite brushes for supplying the windings.

[0003] During motor operation, the currents flowing through the stator phase windings and rotor windings generate significant heat that must be dissipated. Several solutions currently exist for cooling the motor. One such solution involves spraying a cooling fluid inside the motor so that it comes into contact with the stator phase windings and rotor windings. However, this solution has the drawback of not spraying the cooling fluid directly onto the stator phase windings and rotor windings, resulting in increased cooling fluid consumption to ensure adequate heat dissipation. Another possible solution, described in US patent 2020 / 106342 A1, involves equipping an electric motor with a wound rotor conforming to the preamble of claim 1.

[0004] The invention therefore aims to provide a wound rotor and an electric motor comprising such a rotor arranged to allow better dissipation of the heat generated during its operation, by cooling the rotor windings and / or the stator windings as closely as possible, and not presenting the disadvantages of the existing solutions described previously.

[0005] To this end, the invention relates to a wound rotor for an electric motor comprising: a rotor shaft mounted to rotate about an axis; a lamination package mounted coaxially on the rotor shaft, said lamination package extending between a front side face and a rear side face and having an alternation of poles and interpole spaces; a front winding flange and a rear winding flange mounted coaxially on the rotor shaft and arranged axially on either side of the lamination package so as to be contiguous respectively to the front and rear side faces of the lamination package, said front and rear winding flanges each having a series of T-shaped radial branches, each of said radial branches being axially aligned with one of the poles of the lamination package and preferably having a profile similar or identical to that of said pole in a plane perpendicular to the axis of the shaft;windings partially surrounding the poles of the lamination pack and the radial arms of the front and rear winding flanges; in which the shaft is provided with at least one internal channel for the circulation of a cooling fluid, called a fluid inlet channel, and in that the front winding flange and / or the rear winding flange is traversed by several radial fluid outlet channels oriented radially with respect to the axis of the shaft and within which a cooling fluid can circulate, each of said radial fluid outlet channels being in fluidic communication with said fluid inlet channel and opening at a radial fluid outlet opening located at the external periphery of said front winding flange and / or said rear winding flange, characterized in that the front, or respectively rear, winding flange is also traversed by a plurality of intermediate channels, each of said intermediate channels being oriented orthogonally to one of the radial fluid outlet channels and opening, at a first end,in said radial fluid outlet channel and, at a second end, in an axial fluid outlet channel opening at an axial fluid outlet opening located on an external lateral face of said front, or rear, winding flange.

[0006] Thus configured, the rotor of the invention can advantageously be cooled by means of a cooling fluid circulating inside the rotor shaft and then inside the front and / or rear winding flange, said cooling fluid being able to then be projected directly onto the stator windings at the radial fluid outlet openings, thus allowing better heat dissipation from the electric motor incorporating the rotor of the invention.

[0007] The rotor of the invention may also include one or more of the following features: The shaft is provided with a first internal channel for the circulation of a cooling fluid, called the first fluid inlet channel, and a second internal channel for the circulation of a cooling fluid, called the second fluid inlet channel, and the front winding flange, respectively the rear winding flange, is traversed by several radial fluid outlet channels oriented radially with respect to the axis of the shaft and within which a cooling fluid can circulate, each of said radial fluid outlet channels being in fluidic communication with the first fluid inlet channel, respectively the second fluid inlet channel, and opening at the level of a radial fluid outlet opening located at the external periphery of said front winding flange, respectively said rear winding flange.The shaft comprises a front end portion and a rear end portion separated from the front end portion by a central portion, the front end portion, respectively the rear end portion, being traversed by a blind hole aligned with the axis of the shaft, said blind hole forming the first fluid inlet channel, respectively the second fluid inlet channel. The shaft comprises a front end portion and a rear end portion separated from the front end portion by a central portion, the central portion and at least partially the front and rear end portions being traversed by a blind hole aligned with the axis of the shaft, said blind hole forming the fluid inlet channel.Several connecting holes oriented radially with respect to the shaft axis are formed inside the front end portion, respectively the rear end portion, so as to open, on one side, into the fluid inlet channel, or respectively into the first and second fluid inlet channels, and, on the other side, into the radial fluid outlet channels. Each of the radial fluid outlet channels passes through one of the radial branches of the front, respectively rear, winding flange.The front, or rear, winding flange has an inner side face in contact with the front, or rear, side face of the lamination pack. This inner side face has a cavity into which a cover is fitted. This cavity is configured to form, in combination with the cover, a first section of the radial fluid outlet channels, as well as the intermediate and axial fluid outlet channels. The cavity comprises a central annular portion extending radially from a central recessed area of ​​the front, or rear, winding flange. This central area is configured to partially house the rotor shaft. Several radial extensions extend radially from this central portion. Each radial extension is aligned with one of the radial branches of the front, or rear, winding flange.The cavity is delimited by a bottom wall and several side walls oriented perpendicular to said bottom wall. The bottom wall is provided with first grooves oriented radially with respect to the shaft axis and second grooves oriented orthoradially with respect to the shaft axis. These first and second grooves, in combination with corresponding grooves in the cover, form respectively the first section of the radial fluid outlet channels and the intermediate channels. Several side walls, which are oriented radially with respect to the shaft axis, are provided with third grooves oriented parallel to the shaft axis. These third grooves, in combination with corresponding grooves in the cover, form the axial fluid outlet channels.The cavity is configured to form housings arranged radially around the central part, each housing having a specific shape and designed to receive a corresponding connecting element of the cover having a shape complementary to that of said housing. This specific shape and the complementary shape are configured to prevent any relative movement between the cover and the front and rear winding flanges, respectively, in a radial direction, thus securing the coupling of the cover to the front and rear winding flanges, respectively. The housings of the cavity have a dovetail shape. The front and rear winding flanges are made of a material selected from aluminum or a plastic.

[0008] The invention also relates to an electric motor comprising a wound rotor as defined above and an annular stator which surrounds the rotor coaxially with the shaft, windings projecting axially on either side of the stator, the radial fluid outlet openings, through which the cooling fluid from the front and / or rear winding flanges exits, being aligned axially with the windings so as to allow cooling of said windings by means of said cooling fluid.

[0009] The invention will be better understood upon reading the following non-limiting description, made with reference to the figures attached hereto. [ Fig. 1 ] is a perspective view of an electric motor equipped with a wound rotor according to the invention, the motor being viewed from its front side, [ Fig. 2 ] is a view similar to the figure 1 , the engine being viewed from its rear side, [ Fig. 3 ] is a longitudinal cross-sectional view of the engine of the figures 1 et 2 , [ Fig. 4 ] is a perspective view of the wound rotor equipping the motor of the figures 1 et 2 , [ Fig. 5a ] is a longitudinal cross-sectional view of the rotor of the figure 4 , [ Fig. 5b ] is a longitudinal cross-sectional view of a rotor according to an embodiment of the invention, [ Fig. 6 ] is an axial view of one of the winding flanges equipping the rotor of the figure 4 , [ Fig. 7 ] is a perspective view of the inner face of the flange shown on the figure 6 , the lid having been removed, , Fig. 8 ] is a perspective view of the external face of the flange shown on the figure 6 , [ Fig. 9 ] is a perspective view of the external face of the flask lid shown on the figure 6 , [ Fig. 10 ] is a perspective view of the inner face of the flask lid shown on the figure 6 .

[0010] Throughout this description and in the claims, the terms "axial" and "radial" and their derivatives are defined with respect to the rotor's axis of rotation. Thus, an axial orientation refers to an orientation parallel to the rotor's axis of rotation, and a radial orientation refers to an orientation perpendicular to the rotor's axis of rotation. An orthoradial orientation refers to an orientation perpendicular to a radial orientation in a plane perpendicular to the rotor's axis of rotation. Furthermore, by convention, the terms "front" and "rear" refer to separate positions along the rotor's axis of rotation. In particular, the "front" end of the rotor shaft corresponds to the end of the shaft on which a pulley, pinion, or spline can be mounted for transmitting the rotor's rotational motion to any other similar motion transmission device.

[0011] THE figures 1 à 3 represent an electric motor 1 according to the invention comprising two bearings, respectively a front bearing 2 in the shape of a bell and a rear bearing 3 in the shape of a disc, connected together by means of screws 4, the front bearing 2 housing a rotor 10 fixed in rotation to a shaft 12 and an annular stator 11 which surrounds the rotor 10 coaxially with the shaft 12. As shown in figure 3 The front and rear bearings 2 and 3 each centrally support a ball bearing 5 and 6 respectively for the rotational mounting of the shaft 12. Pins 13 project axially on either side of the stator 11 and are housed in the intermediate space separating the stator 11 from the respective bearings 2 and 3. The front and rear bearings 2 and 3 are advantageously made of metal. In the configuration shown, the front bearing 2 is provided with a series of openings 7 which serve for the evacuation of a cooling fluid to the outside of the motor 1. This cooling fluid can enter the internal space defined by the front and rear bearings 2 and 3 via a first internal circulation channel 124, called the first fluid inlet channel, and a second internal cooling fluid circulation channel 126, called the second fluid inlet channel.The first and second fluid inlet channels 124, 126 are respectively defined by blind holes aligned along the X axis of the shaft 12 and formed through front end portions 121 and rear end portions 123 of the shaft 12, said end portions 121, 123 being separated by a solid central portion 122.

[0012] THE figures 4 And 5arepresent a rotor 10 according to a particular embodiment of the invention. The rotor 10 is of the wound type and includes, in particular, a lamination stack 14 formed by an axial stack of laminations extending in a radial plane perpendicular to the X-axis of the shaft 12. The lamination stack 14 is mounted coaxially on the shaft 12. The shaft 12 can be press-fitted into a central opening in the lamination stack 14 so as to rotationally link the rotor body to the shaft 12. The lamination stack 14 extends between a front lateral face 143 and a rear lateral face 144 and has a circumferential alternation of poles 141 and interpole spaces 142. The interpole spaces 142 extend between two adjacent poles 141 and form recesses extending along the entire length of the lamination stack 14, between the two adjacent poles 141.In the configuration shown, there are six poles 141 arranged around the shaft 12 at regular intervals, with two adjacent poles 141 separated by an angle of approximately 60°. The poles 141 extend radially from an annular portion of the lamination stack 14, which has a central opening 149 configured to partially accommodate the rotor shaft 12. Each pole 141 has a T-shaped profile in a plane orthogonal to the X-axis and, in the radial direction, a narrow section extended by a widened, convex section. The widened, convex section has an external peripheral surface 147 which, in the mounted position of the rotor 10, faces an internal peripheral surface 111 of the stator 11 (see . figure 3 ), said external peripheral surface 147 being separated from said internal peripheral surface 111 by a distance of less than 1 mm.

[0013] Each pole 141 receives a longitudinal winding 16 intended to generate a magnetic flux in the rotor pole. The windings 16 are wound around the poles 141 and around front winding flanges 15 and rear winding flanges 15' which axially enclose the lamination stack 14. These flanges 15, 15' are mounted coaxially on the rotor shaft 12 and arranged axially on either side of the lamination stack 14 so as to be contiguous respectively with the front and rear lateral faces 143, 144 of the lamination stack 14.

[0014] With reference to the figure 6 The inner lateral face 153 of the front winding flange 15, which is oriented towards the lamination pack 14, is shown. Since the front and rear winding flanges 15 and 15' have the same profile, the structural details given below are provided with reference to the figure 6 also apply to the rear winding flange 15'. The front winding flange 15 has a series of T-shaped radial arms 151. Each of the radial arms 151 is axially aligned with one of the poles 141 of the lamination pack 14 and, in the preferred configuration shown in the figure 4 , a profile similar or identical to that of the pole 141 with which it is aligned in a plane orthogonal to the X axis of the shaft 12. Thus, each radial branch 151 presents, in the radial direction, a narrow section 152 extended by a widened section 154 of convex shape.

[0015] The front winding flange 15 is also provided with a central cavity 21 in which a front cover 22 is housed. As described in detail in the following paragraphs, the cavity 21 and the front cover 22 are configured to form a plurality of fluid circulation channels inside the front winding flange 15. These fluid circulation channels communicate fluidically with the first fluid inlet channel 124 of the shaft 12 and open, in particular, at fluid outlet openings located on the outer periphery of said front winding flange 15 and oriented towards the stator windings 13 of the stator 11 or towards the windings 16. Thus, as shown in the figure 5a A cooling fluid F1 supplied from the first fluid inlet channel 124 can circulate inside the front winding flange 15 via said fluid circulation channels before being projected towards the windings 13 and / or the windings 16, thus enabling efficient cooling of the rotor 10 and the stator 11. Similarly, a cooling fluid F2 supplied from the second fluid inlet channel 126 can circulate inside similar fluid circulation channels formed inside the rear winding flange 15' before being projected towards the windings 13 protruding from the rear of the stator 11, and / or the windings 16 surrounding the radial arms of the rear winding flange 15'.

[0016] In one embodiment of the invention, shown in the figure 5b It will be possible to introduce a cooling fluid F into the rotor 10 via a single internal circulation channel 124, called the fluid inlet channel, opening at the front end portion 121 of the shaft 12. In the configuration shown, the fluid inlet channel 124 is defined by a blind hole aligned along the X axis of the shaft 12 and formed successively through the front end portion 121, the central portion 122 and a part of the rear end portion 123 of the shaft 12.Thus, the cooling fluid F supplied from the fluid inlet channel 124 will be able to circulate successively inside the front winding flange 15 via fluid circulation channels formed inside said front winding flange 15 before being projected towards the buns 13 and / or the windings 16, then inside similar fluid circulation channels formed inside the rear winding flange 15' before being projected towards the buns 13 protruding at the rear of the stator 11, and / or the windings 16 surrounding the radial arms of the rear winding flange 15'.

[0017] In another possible configuration (not shown), a single fluid inlet channel may open at the rear end portion 123 of the shaft 12. It may be defined by a blind hole aligned along the X axis of the shaft 12 and formed successively through the rear end portion 123, the central portion 122 and a part of the front end portion 121 of the shaft 12.Thus, the cooling fluid supplied from the fluid inlet channel will be able to circulate successively inside the rear winding flange 15' via fluid circulation channels formed inside said rear winding flange 15' before being projected towards the buns 13 and / or the windings 16, then inside similar fluid circulation channels formed inside the front winding flange 15 before being projected towards the buns 13 protruding in front of the stator 11, and / or the windings 16 surrounding the radial arms of the front winding flange 15.

[0018] In another possible configuration (not shown), a single fluid inlet channel may open at the front end portion 121 or rear end portion 123 of the shaft 12. It may be defined by a blind hole aligned along the X axis of the shaft 12 and formed only through the front end portion 121 or rear end portion 123. In this configuration, only the front winding flange 15, or rear winding flange 15', will be traversed by fluid circulation channels, such that only the windings 13 protruding at the front, or rear, of the stator 11 and / or the windings 16 surrounding the radial branches of the front winding flange 15, or rear winding flange 15', will be cooled by the cooling fluid.

[0019] A particular configuration of the front winding flange 15 and its associated front cover 22 is shown in the figures 7 à 10 . The 15' rear winding flange having a structure substantially identical to that of the 15' front winding flange, the technical details given below will apply similarly to the 15' rear winding flange and its associated rear cover.

[0020] The front winding flange 15 is substantially in the form of a star-shaped structure comprising a central hexagonal part 156 extended on each of its sides by the T-shaped radial branches 151. The central part 156 has a central hollowed area 157, which is configured to partially house the rotor shaft 12.

[0021] The front winding flange 15 has an internal side face 153 (visible on the figure 7 ) and an external lateral face 155 (visible on the figure 8 ). The inner side face 153 is in contact with the front side face 143 of the sheet metal pack 14 and the outer side face 155 is oriented towards the front bearing 2.

[0022] The external side face 155 is configured to define between the enlarged section 154 of each radial branch 151 and the central part 156 a radial space allowing to accommodate the windings 16.

[0023] The inner lateral face 153, which is mostly flat, has a central cavity 21 which extends radially from the central area 157 towards the outer peripheral faces 158 of the front winding flange 15, which are defined by the curved outer sides of the enlarged sections 154 of the radial arms 151.

[0024] The cavity 21 includes in particular a central portion 21a of annular shape, which adjoins the central zone 157, and several radial extensions 21b extending radially from said central portion 21a. Each of the radial extensions 21b is aligned with one of the radial branches 151 of the front winding flange 15 and includes a narrow portion 21b1 extended radially by a widened portion 21b2.

[0025] The cavity 21 is notably delimited by a bottom wall 211, by several lateral walls 212 oriented radially with respect to the X axis, and by several lateral walls 213 oriented orthoradially with respect to the X axis.

[0026] The bottom wall 211 is provided with first grooves 214 oriented radially with respect to the X axis and second grooves 215 oriented orthoradially with respect to the X axis. The side walls 212 are, for their part, provided with third grooves 218 oriented parallel to the X axis, each of the third grooves 218 opening onto an axial fluid outlet opening 220 located on the external side face 155 of the winding flange 15, at the level of the radial space which serves as housing for the windings 16.

[0027] In the configuration shown, there are six of the first grooves 214, each of the first grooves 214 being formed through the central part 21a and the narrow and widened portions of one of the radial extensions 21b and extending from a first end adjoining the central area 157 to a second end located at one of the lateral walls 213 of the cavity 21. This second end opens into a through opening 217 (shown in dotted lines on the figure 7 ) formed through the enlarged section 154 of one of the radial branches 151. This through opening 217 opens outside the winding flange 15 at the level of a radial fluid outlet opening 219 which is oriented towards the coils 13 of the stator 11.

[0028] In the configuration shown, there are 36 second grooves 215, each second groove 215 being formed through the enlarged portion 21b2 of one of the radial extensions 21b and extending from a first end adjoining one of the first grooves 214 to a second end located at one of the lateral walls 212 of the cavity 21. This second end opens onto one of the third grooves 218.

[0029] The first, second and third grooves 214, 215 and 218 are configured to form, in combination with corresponding grooves of the front cover 22, fluid circulation channels inside the front winding flange 15.

[0030] To this end, and as shown on the figures 9 And 10 , the cover 22 has a shape complementary to the cavity 21 of the winding flange 15.

[0031] The cover 22 includes, in particular, a central annular portion 22a designed to fit inside the central portion 21a of the cavity 21. In order to secure the coupling of the cover 22 to the winding flange 15, the cover 22 is advantageously provided with dovetail ribs 226 forming projections on the outer periphery of the central portion 22a of the cover 22, said ribs 226 having a shape complementary to that of corresponding recessed shapes 216 of the winding flange 15 (see figure 7 ), each of the said hollow forms 216 being intended to house one of the said ribs 226.

[0032] The cover 22 also includes several radial extensions 22b extending radially from the central portion 22a. Each radial extension 22b comprises a narrow portion 22b1 extended radially by a wider portion 22b2. The radial extensions 22b are designed to fit inside the radial extensions 21b of the cavity 21.

[0033] The lid 22 is notably delimited by an internal wall 221, which is in contact with the bottom wall 211 of the cavity 21, by an external wall 229, which is opposite the internal wall 221, by several lateral walls 222, which are in contact with the lateral walls 212 of the cavity 21, and by several lateral walls 223, which are in contact with the lateral walls 213 of the cavity 21.

[0034] The inner wall 221 is provided with first grooves 224 oriented radially with respect to the X-axis and forming, in combination with the first grooves 214 of the cavity 21, first sections of radial fluid outlet channels for the front winding flange 15. Each of these first sections opens, at its distal end, into one of the through openings 217 of the winding flange 15, which form second sections of said radial fluid outlet channels. Furthermore, each of these first sections opens, at its proximal end, into a through hole 125 formed inside the shaft 12 and oriented radially with respect to the X-axis (see figure 5a), said hole 125 being formed inside the front end portion 121 so as to open, on one side, into the first fluid inlet channel 124 and, on the other side, into the peripheral wall of the shaft 12. Similarly, several holes 127 oriented radially with respect to the X-axis of the shaft 12 are formed inside the rear end portion 123 so as to open, on one side, into the second fluid inlet channel 126 and, on the other side, into the peripheral wall of the shaft. These holes 125, 127 will supply fluid to the radial fluid outlet channels of the front and rear winding flanges 15, 15' respectively.

[0035] The inner wall 221 is also provided with second grooves 225 oriented orthoradially with respect to the X-axis and forming, in combination with the second grooves 215 of the cavity 21, intermediate fluid circulation channels for the front winding flange 15, said intermediate fluid circulation channels being in fluidic communication with the radial fluid outlet channels. These intermediate fluid circulation channels are supplied with fluid by the first sections of the radial fluid inlet channels formed by the grooves 214 and 224.

[0036] The side walls 222 of the cover 22 are provided with third grooves 228 oriented parallel to the X-axis and forming, in combination with the third grooves 218 of the cavity 21, axial fluid outlet channels for the front winding flange 15, said axial fluid outlet channels being in fluidic communication with the intermediate fluid circulation channels. Each of the axial fluid outlet channels thus opens into the axial fluid outlet opening 220 located on the external side face 155 of the winding flange 15.

[0037] Thus configured, the rotor 10 and the motor 1 can be cooled by a cooling fluid, such as oil or pressurized air for example, said cooling fluid circulating in the rotor 10 successively through the first fluid inlet channel 124 and / or the second fluid inlet channel 126, then inside the front and / or rear winding flanges 15, 15' through the radial fluid outlet channels, the intermediate fluid circulation channels and / or the axial fluid outlet channels, to finally be expelled out of the rotor 10 through the radial fluid outlet openings 219 and / or the axial fluid outlet openings 220.Subsequently, this cooling fluid is directed towards the coils 13 and / or the windings 16 in such a way that, once in contact with the coils 13 and / or the windings 16, it can extract some of the heat stored in said coils 13 and / or by said windings 16. The cooling fluid then circulates, under the effect of gravity, in the lower part of the housing before being discharged through the openings 7.

[0038] The invention is obviously not limited to the embodiments described above. Furthermore, the presence of a cover 22 housed within a central cavity 21 of the front winding flange 15, or rear one 15', is only one possibility for forming the fluid circulation channels. In other embodiments of the invention, it is conceivable not to provide such a cover and cavity.

Claims

1. A wound rotor (10) for electric motor (1) comprising: - a rotor shaft (12) rotary mounted about an axis (X); - a stack of laminations (14) mounted coaxially on the rotor shaft (12), said stack of laminations (14) extending between a front lateral face (143) and a rear lateral face (144) and having an alternation of poles (141) and interpolar spaces (142); - a front winding flange (15) and a rear winding flange (15') mounted coaxially on the rotor shaft (12) and arranged axially on either side of the stack of laminations (14) so as to be contiguous respectively to the front and rear lateral faces (143, 144) of the stack of laminations (14), said front and rear winding flanges (15, 15') each having a series of radial branches (151) in the shape of a T, each of said radial branches (151) being aligned axially with one of the poles (141) of the stack of laminations (14) and preferably having a profile similar or identical to that of said pole (141) in a plane perpendicular to the axis (X) of the shaft; - windings (16) partially surrounding the poles (141) of the stack of laminations (14) and the radial branches (151) of the front and rear winding flanges (15, 15'); in which the shaft (12) is provided with at least one internal channel (124) for circulating a cooling fluid, called a fluid inlet channel, and in that the front winding flange (15) and / or the rear winding flange (15') is crossed by several radial fluid outlet channels (214, 224, 217) oriented radially relative to the axis (X) of the shaft and inside which can circulate a cooling fluid, each of said radial fluid outlet channels (214, 224, 217) being in fluid communication with said fluid inlet channel (124) and opening at a radial fluid outlet opening (219) located at the external periphery (158) of said front winding flange (15) and / or said rear winding flange (15'), characterized in that the front (15), respectively rear (15') winding flange, is also crossed by a plurality of intermediate channels (215, 225), each of said intermediate channels (215, 225) being orthogonally oriented to one of the radial fluid outlet channels (214, 224) and opening, at a first end, into said radial fluid outlet channel (214, 224) and, at a second end, into an axial fluid outlet channel (218, 228) opening at the level of an axial fluid outlet opening (220) located on an external lateral face (155) of said front (15), respectively rear (15') winding flange.

2. The wound rotor (10) according to claim 1, characterized in that the shaft (12) is provided with a first internal channel (124) for circulating a cooling fluid, called first fluid inlet channel, and a second internal channel for circulating a cooling fluid, called second fluid inlet channel, and in that the front winding flange (15), respectively the rear winding flange (15'), is crossed by several radial fluid outlet channels (214, 224, 217) oriented radially relative to the axis (X) of the shaft and inside which a cooling fluid can circulate, each of said radial fluid outlet channels (214, 224, 217) being in fluid communication with the first fluid inlet channel (124), respectively the second fluid inlet channel (126), and opening at a radial fluid outlet opening (219) located at the external periphery (158) of said front winding flange (15), respectively of said rear winding flange (15').

3. The wound rotor (10) according to claim 2, characterized in that the shaft (12) comprises a front end portion (121) and a rear end portion (123) separated from the front end portion (121) by a central portion (122), the front end portion (121), respectively the rear end portion (122), being crossed by a blind hole (124, 126) aligned along the axis (X) of the shaft (12), said blind hole forming the first fluid inlet channel (124), respectively the second fluid inlet channel (126).

4. The wound rotor (10) according to claim 1, characterized in that the shaft (12) comprises a front end portion (121) and a rear end portion (123) separated from the front end portion (121) by a central portion (122), the central portion (122) and at least partially the front (121) and rear (123) end portions being crossed by a blind hole (124) aligned along the axis (X) of the shaft (12), said blind hole forming the fluid inlet channel (124).

5. The wound rotor (10) according to claim 3 or 4, characterized in that several connecting holes (125) oriented radially relative to the axis (X) of the shaft are formed inside the front end portion (121), respectively the rear end portion (123), so as to open, on one side, into the fluid inlet channel (124), or respectively into the first and second fluid inlet channels (126), and, on the other side, in the radial fluid outlet channels (214, 224).

6. The wound rotor (10) according to any of the preceding claims, characterized in that each of the radial fluid outlet channels (214, 224, 217) passes through one of the radial branches (151) of the front (15), respectively rear (15') winding flange.

7. The wound rotor (10) according to any of the preceding claims, characterized in that the front (15), respectively rear (15') winding flange, has an internal lateral face (153) in contact with the front (143), respectively rear (144) lateral face, of the stack of laminations (14), said internal lateral face (153) being provided with a cavity (21) in which a cover (22) is housed, said cavity (21) being configured to form, in combination with said cover (22), a first section (214, 224) of the radial fluid outlet channels, as well as the intermediate channels (215, 225) and the axial fluid outlet channels (218, 228).

8. The wound rotor (10) according to claim 7, characterized in that the cavity (21) comprises a central part (21a) of annular shape, which extends radially from a hollowed central zone (157) of the front (15), respectively rear (15') winding flange, said central zone (157) being configured to partially house the shaft (12) of the rotor, and several radial extensions (21b) extending radially from said central part (21a), each of the radial extensions (21b) being aligned with one of the radial branches (151) of the front (15), respectively rear (15') winding flange,9. The wound rotor (10) according to claim 8, characterized in that the cavity (21) is delimited by a bottom wall (211) and by several lateral walls (212, 213) oriented perpendicular to said bottom wall (211), said bottom wall (211) being provided with first grooves (214) oriented radially relative to the axis (X) of the shaft and second grooves (215) oriented orthoradially relative to the axis (X) of the shaft, said first and second grooves (214, 215) forming respectively, in combination with corresponding grooves (224, 225) to the cover (22), the first section (214, 224) of the radial fluid outlet channels and the intermediate channels (215, 225).

10. The wound rotor (10) according to claim 9, characterized in that several lateral walls (212), which are oriented radially relative to the axis (X) of the shaft, are provided with third grooves (218) oriented parallel to the axis (X) of the shaft, said third grooves (218) forming, in combination with corresponding grooves (228) of the cover (22), the axial fluid outlet channels (218, 228).

11. The wound rotor (10) according to any of claims 8 to 10, characterized in that the cavity (21) is configured to form housings (216) arranged radially about the central part (21a), each of the housings (216) having a specific shape and being intended to receive a connecting element (226) corresponding to the cover (22) having a shape complementary to that of said housing (216), said specific shape and said complementary shape being configured to prevent any relative movement between the cover (22) and the front (15), respectively rear (15') winding flange, in a radial direction, thus securing the coupling of the cover (22) on the front (15), respectively rear (15') winding flange.

12. The wound rotor (10) according to claim 11, characterized in that the housings (216) of the cavity (21) have a dovetail shape.

13. The wound rotor (10) according to any of the preceding claims, characterized in that the front and rear winding flanges (15, 15') are made of a material selected from aluminum or a plastic material.

14. An electric motor (1) comprising a wound rotor (10) according to any of the preceding claims and an annular stator (11) which surrounds the rotor (10) coaxially with the shaft (12), winding heads (13) projecting axially from either side of the stator (11), characterized in that the radial fluid outlet openings (219), through which the cooling fluid exits the front and / or rear winding flanges (15, 15'), are aligned axially with the winding heads (13) so as to allow a cooling of said winding heads (13) via said cooling fluid.