Wound discoid rotor for axial flux electric machine.

Abstract

Wound discoid rotor 1 for axial magnetic flux electric machine 100 consisting of: two flanges 10a,10b of composite material and a steel band 20, assembled by two sets of rivets 50,51 and forming an annular chamber 10c; rotor cores 30, in even number, supported at each end by the flanges 10a,10b, and each carrying a coil 40 arranged in the annular chamber 10c; two commutators 41,42 connected one to the end of the wire 40a of each coil 40 and the other to the end of the wire 40b of each coil;of two electrical power supply wires 43, 44, one connected to the outer collector 41, the other to the inner collector 42, characterized in that: each flange 10a, 10b is pierced with as many inclined air inlet ducts 17a, 17b as there are coils, close to the inner diameter 10d of the annular chamber 10c, connecting this annular chamber with the ambient internal space of the electrical machine 100 contained in the housing 110 closed by the closing flange 111; the ring 20 has as many air outlet openings 21 as there are coils, creating a second communication between the annular chamber 10c and the ambient internal space of the electrical machine 100 contained in the housing 110 closed by the closing flange 111, creating, during the rotation of the discoidal rotor, a flow coil cooling air 40 entering through inclined air inlet ducts 17a,17b and exiting through air outlet openings 21. Figure for abbreviation: Fig.2;

Description

Title of the invention: Wound discoid rotor for axial flux electric machine. TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to an axial flux electric machine comprising a disc-shaped rotor framed by two stators.

[0002] More specifically, the rotor's distinctive feature is that it has no permanent magnet. The magnetic flux is generated by metallic cores, each surrounded by a coil. This rotor can be described as a wound rotor. STATE OF THE ART

[0003] There are many publications disclosing an axial flux electrical machine.

[0004] In the architecture comprising a central stator and two lateral rotors, publication WO2022 / 185403 can be cited as an example. In all publications, the rotors are disks on which permanent magnets are attached.

[0005] In the architecture comprising a central rotor framed by two lateral stators, one can cite publication FR3064422. The rotor is equipped with strongly segmented magnet blocks.

[0006] Radial flux wound rotor electric machines have been marketed by very few electric vehicle manufacturers and among the few axial magnetic flux electric machines on the market, there are none with a wound discoid rotor.

[0007] However, this type of machine has the advantage of not requiring permanent magnets and therefore rare earths, and the magnetic field generated by the rotor coils is adjustable.

[0008] In all publications concerning axial magnetic flux electric machines, with a few rare exceptions, the rotors are disks on which permanent magnets are attached.

[0009] Among the exceptions is publication CN218678605U. The single figure in this publication shows a rotor made up of three discs with two notches, each carrying two coils in a spiral shape, which, after a particular stacking at a 60° angle, forms an assembly of six regularly spaced coils. The single figure is not explicit regarding the flow of electrical current and the supply of power to the coils. PRESENTATION OF THE INVENTION

[0010] The object of this invention is a discoid rotor, for an axial flux electric machine, equipped with coils.

[0011] Since the coils are supplied with electric current, the specific device for supplying electric current is described, without being the object of the invention.

[0012] The axial magnetic flux electric machine, which can operate with a wound discoid rotor, has a central rotor and lateral stator architecture. The rotor is confined between two annular heat-emitting elements and has its own losses due to Joule heating and eddy currents. The object of the invention relates to the cooling method, which depends on the machine's structure and therefore requires its description.

[0013] According to a first characteristic, the discoid rotor comprises a base, carrying rotor cores each surrounded by a coil, made up of two flanges in composite material and a peripheral steel reinforcement ring forming with the flanges an annular chamber containing the coils, the two flanges being joined by a first series of rivets, in number equal to that of the cores, arranged on a diameter less than the inner diameter of the annular chamber, the two flanges and the reinforcement ring being joined by a second series of rivets, in number equal to that of the cores, arranged on the outer diameter of the annular chamber.

[0014] According to a second feature, the flanges have trapezoidal type openings corresponding precisely to the section of the rotor cores which pass through the wall and are flush with the outer surface of the flanges.

[0015] According to a third characteristic, the rotor cores, which conduct the magnetic fields generated by the coils and also by those generated by the stator pads, are made of SMC (Soft Magnetic composite), or are laminates of electrically insulated iron sheets, or are bundles of electrically insulated iron wires.

[0016] According to a fourth feature, the rotor cores are externally overmolded with an electrically insulating material over their entire length and in two distinct thicknesses: • the strongest one, in the center, serves as a cradle for a coil and axially supports the core because its external dimensions are greater than those of the openings in the flanges and its length is equal to the width of the annular chamber; • The thinner one at each end gives the core the same final external dimensions as the openings in the flanges and its length is equal to the thickness of the flange fabric.

[0017] According to a fifth feature, in the space of the annular chamber closest to the axis of rotation, two closed circular collectors supply the coils, in even number, the two ends of the conducting wire of these coils being fixed, for example by welding, to each of the two collectors, such that: the connections result in coils connected in parallel; • the connections of two consecutive coils are reversed to create reversed magnetic fields.

[0018] According to a sixth feature, from each circular collector a power supply wire which passes through the wall of the same flange through a hole close to the inner diameter of the annular chamber.

[0019] According to a seventh feature, in each flange, close to the inner diameter of the annular chamber, and under each coil, an inclined bore connects the annular chamber to the ambient environment of the discoid rotor. The inclination of the bores is such that it facilitates the entry of air into the annular chamber when the discoid rotor rotates in the main direction. In other words, if the machine is fitted to a motor vehicle, the main direction is forward.

[0020] According to an eighth feature, in the reinforcing band, opposite each coil, an opening puts the annular chamber in communication with the ambient environment of the discoid rotor and under the centrifugal effect promotes the extraction of air from the annular chamber.

[0021] According to a ninth feature, the coils, supported by the rotor cores, are recessed from the inner and outer diameters of the annular chamber, spaced apart from each other, and thus a cooling airflow is established from the inclined holes in the flanges to the openings in the reinforcing band, and this flow is all the more intense as the rotor rotation speed is high. DETAILED DESCRIPTION OF THE INVENTION

[0022] These features, objectives and advantages of the present invention will become apparent from the detailed description that follows and from the accompanying drawings given by way of non-limiting examples and on which:

[0023] [Fig-1] is a front view of the assembled disk.

[0024] [Fig.2] is a front view of the incomplete disc, without the peripheral reinforcing band and without the front flange.

[0025] [Fig.3] is a first section AA of the assembled disk.

[0026] [Fig.4] is a second BB section of the assembled disk.

[0027] [Fig.5] is a third CC section of the assembled disc.

[0028] [Fig.6] is a set of front views of the rotor housing, zooms on the material component and a partial cross-sectional view of the rotor disc zooming in on the overmolding of the rotor pad.

[0029] [Fig.7] is a cross-sectional view of the electrical machine.

[0030] [Fig.8] is a cross-sectional view of the rotor's electrical power supply device.

[0031] [Fig.9] is a view of the cooling airflow in the rotor disc.

[0032] [Fig. 10] is a view of the rotor cooling airflow in the com enclosed compartment of the electrical machine and a partial view of the stator cooling device.

[0033] [Fig. 1] is a front view of the discoid rotor 1 for an axial magnetic flux electric machine 100. This rotor comprises 2 flanges, flange 10a is shown from the front in this view.

[0034] It has trapezoidal type openings 1 la, always even in number but variable according to the performance sought for the electric machine, which carry one end of the magnetically conductive rotor cores 30.

[0035] We have a circular centering opening 12a which serves to position the discoid rotor 1 on its guide bearing.

[0036] On a first diameter, we have a series of drillings. These are the screw holes 13a for fixing the discoid rotor 1 and the pin holes 14a for contributing to the transmission of torque.

[0037] On a second diameter we have circular areas of withdrawal 15a with respect to the surface, of the same number as the rotor cores 30, occupied by the heads of the rivets 50 for joining the two flanges.

[0038] On a slightly larger diameter, we have a series of inclined air inlet ducts 17a, from the air inlet 17a1 on the outer surface of the flange 10a to the air outlet 17a2 on the inner surface (specified later). The air inlet ducts will only be effective for the direction of rotation 2. For an electric motor equipping a vehicle, this direction of rotation must be that corresponding to forward motion.

[0039] Finally, on a peripheral diameter, we have semi-circular zones 16a set back from the surface, of the same number as the rotor cores 30, occupied by the heads of the rivets 51.

[0040] These rivets 51 secure the two flanges with the peripheral band 20 locally on its internal protrusions 20a, which are narrower than the band itself and on which the two flanges are pressed (see [Fig.3]).

[0041] The role of this ring 20, on which the flanges can be centered with radial clamping, is to substantially increase the opposition of the flanges to the centrifugal forces generated by the rotor cores 30, each of which carries a coil, and to allow a higher limiting rotational speed.

[0042] The mention of air inlet ducts 17a means internal air circulation within the discoidal rotor 1. This circulation will be natural because the air outlet openings 21 are on the periphery in the ring 20 and opposite each rotor core 30.

[0043] [Fig.2] is a front view of the discoidal rotor 1 without the ring 20 and the flange 10a present in [Fig. 1]. This figure shows a view of the inside of the discoid rotor 1.

[0044] We see the inner face of the flange 10b, and find the same openings, a centering opening 12b which serves to position the discoid rotor 1 on its bearing guide holes, screw passage holes 13b for discoid rotor fixing and pin passage holes 14b for contribution to torque transmission.

[0045] On a second diameter we have the holes 15b for the passage of the internal rivets 50 for joining the two flanges.

[0046] On a slightly larger diameter, we have a series of inclined air ducts 17b from the external air inlet 17b1 to the internal air outlet 17b2.

[0047] The rotor cores 30 each carry a coil 40, connected to the outer commutator 41 by the end of the winding wire 40a and connected to the inner commutator 42 by the end of the winding wire 40b. The coils are connected in parallel.

[0048] Each coil produces a magnetic field always oriented in the same direction. However, two consecutive coils must produce fields in opposite directions. Therefore, the connections of the ends of the winding wires 40a, 40b to the commutators 41, 42 are made in such a way as to obtain this alternation of the field direction. For two adjacent coils, either two connections of the ends of winding wire 40a, or two connections of the ends of winding wire 40b are adjacent.

[0049] These collectors are connected to an external power supply by a power supply wire 43 from the outer collector 41 and a power supply wire 44 from the inner collector 42. These power supply wires 43,44 pass through the wall of the flange 10b.

[0050] Finally, on a peripheral diameter, we have semi-circular recessed areas 16b relative to the external surface of the flange 10b, of the same number as the rotor cores 30, occupied by the heads of the rivets 51 (not shown) implanted in the holes 18b.

[0051] [Fig.3] is section AA of the discoid rotor 1. The two flanges 10a,10b are joined and internally secured by rivets 50. Externally the rivets 51 secure the two flanges 10a, 10b with the band 20 at the level of each internal protrusion 20a.

[0052] The rotor core 30 passes through the two flanges and is externally flush. The coil 40 occupies the entire axial space of the annular chamber 10c formed by the flanges 10a, 10b.

[0053] the annular chamber 10c of the flanges extends towards the axis of rotation under the coils for the passage of the outer collectors 41 and inner collectors 42.

[0054] Close to the diameter lOd, the smallest of the annular chamber 10c, is the inclined air inlet duct 17b, and in the ring 20 the air outlet opening 21 of width slightly less than that of the annular chamber 10c.

[0055] [Fig.4] is section BB of the discoid rotor 1. In the annular chamber 10c formed The external manifolds 41 and internal manifolds 42 are arranged by the two flanges 10a, 10b and reinforcing ring 20.

[0056] These collectors are connected to an external power supply, the collector exterior 41 by the power supply wire 43 and the interior collector 42 and the power supply wire 44.

[0057] These power supply wires 43,44 pass through the wall of the flange 10b through openings 10b1 and 10b2 located at the level of the smallest diameter lOd of the annular chamber 10c.

[0058] [Fig.5] is the CC section of the discoid rotor 1. In the annular chamber 10c each coil is connected to the two collectors 41,42 by the two winding wire ends 40a and 40b.

[0059] [Fig.6] includes three front views of the rotor core, two zooms on the material structure, and also a partial section of the discoid rotor 1 zooming in on the overmolding outside the metal core.

[0060] The core of the rotor core is made of material with the lowest possible reluctance and which must generate the least possible loss by eddy current.

[0061] Core 30a is made of SMC. Core 30b is a stack of thin, electrically insulated sheets of varying widths, forming a shape close to a trapezoid and arranged horizontally as shown in the zoom. Core 30c is a bundle of electrically insulated wires tangent to each other as shown in the zoom.

[0062] Each type of core is surrounded by a peripheral overmolding 31. This overmolding 31 covers the entire length of the core 30a, 30b, 30c. At the ends 31a, the thickness of the overmolding gives the core the final dimension corresponding to the trapezoidal openings 11a and 11b of the flanges 10a, 10b.

[0063] In its central part, the overmolding 31b is thicker and serves two purposes. The first is to axially secure the core. Indeed, by having a perimeter larger than that of the trapezoidal openings 1a, 1b and a length equal to the width of the annular chamber 10c, the overmolding 31b rests laterally on the flanges 10a and 10b. The second purpose of this insulating overmolding 31b is to serve as a cradle for the coil 40, this cradle being completed laterally by the flanges 10a, 10b and the spacer 45 which locally fill the conductor gap.

[0064] [Fig.7] is a cross-sectional view of the axial magnetic flux electric machine 100, equipped with the wound discoid rotor 1. It is contained in the housing 110 closed by the closing flange 111 fixed to the housing by means of the screws 112.

[0065] The electric machine 100 is of the axial magnetic flux type with a single discoid rotor 1. It is framed by the stators 120, 130.

[0066] The stators 120,130 are constructed on the basis of a frame 121,131 provided with a series of openings bordered by an axial extension 121 a, 131a for receiving the stator studs 122,132 glued along their entire length.

[0067] Externally, these axial extensions 121a,131a carry the coils 123,133.

[0068] The magnetic circuit is closed at the rear of the stator pads 122,132 by the annular yokes 124,134 made of rolled sheet metal and glued to the stator pads 122,132.

[0069] The carcasses 121,131 have external axial extensions 121b, 131b and internal 121c, 131c which form hollow annular bodies closed by annular covers 125,135. These stator chambers 127,137 are occupied by the stator pads 122,132, the coils 123,133 and the yokes 124,134 and the remaining free volume allows the circulation of a coolant which will be in direct contact with the coils and the yokes.

[0070] The covers 125,135 are fixed on their inner diameter by the screws 126 and on their outer diameter by the screws 139, a common fixing means with the stator frames on the central spacer 140.

[0071] This central spacer 140, annular, is the intermediate element between the stators 120,130 and the housing 110. On its periphery it has several lugs 140a through which the screws 141 pass on the bearing surfaces 110a.

[0072] In the inner area of ​​this central annular spacer 140, the discoid rotor 1 is arranged. It carries on either side and at a precise distance the two stators 120,130. The thickness of the spacer 140 is precisely equal to the sum of the thicknesses of the discoid rotor 1 and the two air gaps 128.

[0073] Between two consecutive ears 140a, the spacer 140 is set back from the fabric of the housing 110 and provides a passage 145 for air circulation in the internal space formed by the housing 110 and the closing flange 111.

[0074] The housing 110 has a general shape close to a slightly conical cylinder (casting draft) closed on one side by a fabric 110b. In the center of this fabric, in the boss 110c, an axle 150 is fitted without play.

[0075] On its free part extending beyond the boss 110c, the shaft 150 carries a double row ball bearing 160 with angular contact.

[0076] This bearing 160 consists of an outer ring 161, two inner rings 162, 163 between which the balls 164 are interposed. The inner rings 162, 163 are pressed together. This bearing 160 is characterized by the absence of internal play and a slight preload. The ring 163 is indirectly axially supported on the housing 110, because the balancing washer 170 for the air gaps 128 is interposed between the housing and the ring 163. The entire assembly is held tightly by the screw 152 and the pressure washer 151.

[0077] The outer ring 161 has an annular radial extension 161a. On one side of this extension rests the discoidal rotor 1, centered on the outer diameter of the ring 161. On the opposite side is arranged the rotor current supply device 200, secured by screws 201.

[0078] Against the discoid rotor is supported a power transmission hub 180, centered also on the outer diameter of the ring 161 of the bearing 160. The screws 185 pass through the radial extension 161a, the discoid rotor 1 and secure them with the power transmission hub 180.

[0079] The power transmission hub 180 externally carries the rotor 191 of the resolver whose stator 190 is positioned on the closing flange 111. In its hollow part, the power transmission hub 180 accommodates the grounding device 187, protecting the bearing 160 from possible parasitic currents and a ball slide 182 and its grooved ring 181, protecting the machine from external axial stresses detrimental to the stability of the air gaps 128.

[0080] [Fig.8] is a cross-sectional view of the current supply device 200. It includes a first support element 210, made of insulating material, for the other elements that make up this device.

[0081] The first support element 210 is centered by its diameter 210a and is supported by its face 210b on the radial extension 161a of the outer ring 161 of the bearing 160. It is rotationally fixed to this ring by the screws 201 (see [Fig.7]) and is therefore rotationally linked to the discoid rotor 1.

[0082] On the support element 210 is mounted a complementary element 220, also made of insulating material and driven in rotation by the grooves 210c.

[0083] The support element 210 and the complementary element 220, which are rotationally fixed, frame a rotating fixed element 230 made of insulating material.

[0084] The fixed element 230 in the shape of a crown, is centered on the support element 210, has an outgrowth 230a which cooperates with a pin 260, for locking against rotation, screwed into the housing 110 of the electric machine.

[0085] The fixed element 230, made of insulating material, carries on either side the crown-shaped plates 231 and 232 made of conductive material.

[0086] Similarly, the support elements 210 and complementary elements 220 carry opposite the crown-shaped plates 231, 232 respectively crown-shaped plates 211 and 221 also made of conductive material.

[0087] Between the crown-shaped plates 211,231 on the one hand and 221,232 on the other hand are interposed identical transmitting discs 250a and 250b, the first 250a centered by its outer diameter in the support element 210, the second 250b centered by its outer diameter in the complementary element 220, and free to rotate.

[0088] These two transmitting discs 250a, 250b are similar to those of needle bearings, but play a very different role. They are composed of an annular disc 251 made of insulating material which has, on two concentric circles, a large number of rectangular openings in which are inserted cylindrical rollers 252, all identical, made of conductive material, copper or copper alloy, with a diameter greater than the thickness of the annular disc 251.

[0089] These rollers are subjected to a very low axial load which ensures the contact of the greatest possible proportion of rollers 252 with on the one hand the ring-shaped plates 211,231 (transmitting disc 250a) and on the other hand the ring-shaped plates 221,232 (transmitting disc 250b) in order to transmit the electric current from the fixed element 230, connected to an external power supply, to the support element 210 and the complementary element 220 in rotation, connected to the coils of the discoid rotor 1.

[0090] For this purpose, the complementary element 220, the fixed element 230, as well as the transmitting discs 250a, 250b are pressed against each other and against the support element 210 by a wave washer type spring 225, mounted in a circular groove 220b of the complementary element 220, put under tension by the washer 226 held by the stop ring 227 engaged in a groove of the support element 210.

[0091] The choice of a very large number of rollers 252 is the way to split the electric current and limit it, for each contact, to a low intensity level reducing the risks of electric arc and damage.

[0092] The crown-shaped plates 211, 221 have tabs 21la and 221a for connection with the rotor coils. In the embodiment described in this [Fig. 8], the tab 21la is welded to the supply wire 43 of the outer commutator 41, and the tab 221a is welded to the supply wire 44 of the commutator 42.

[0093] The crown-shaped plates 231,232 carried by the fixed element 230 each have a tab 23la,232a for connection with an external power supply device (not shown).

[0094] The tabs 23la,232a exit the housing towards the external supply by passing through the tab guide 240 made of insulating material engaged in the opening 115 of the housing 110 and retained by the stop ring 241.

[0095] To ensure the longevity of the power supply device 200, the rollers 252 will be coated with bearing grease. This grease will be retained confined by the felt seals 255.

[0096] [Fig. 9] is a partial front view of the discoid rotor 1. On the flange 10a, below each coil 40, i.e., the part closest to the axis of rotation, there is an air inlet 17a inclined with respect to the axis of rotation of the discoid rotor 1. This opening is an air circulation duct between the unoccupied volume inside the housing and the unoccupied volume inside the annular chamber 10c. For the direction of rotation 2 indicated, the introduction of air into the annular chamber 10c is facilitated by an air inlet 17a1, related to the internal volume of the housing, which is angularly advanced over the air outlet 17a2, related to the internal volume of the annular chamber 10c. The air outlet 17a2 is centered with respect to the coil 40.

[0097] In the ring 20, the air outlet openings 21 are, conversely, a conduit of air circulation from the annular chamber 10c to the internal volume of the casing, the openings are centered with respect to the coils 40.

[0098] Arranged in this way, the air circulation between the air inlets 17a, 17b and the air outlet 21 of the annular chamber 10c is as follows: • aspiration through air inlets 17a 1,17b 1 and expulsion through air outlets 17a2,17b2 of air inlet ducts 17a,17b inclined along path 60; • the incoming flows are divided at the bottom of the reels 40, equally or not, and bypass them according to the paths 61,62; • the two flows regroup at the top of each coil and exit the annular chamber 10c through the air outlet opening 21 along the path 63.

[0099] [Fig. 10] is a cross-sectional view of the electric machine 100 showing the dual cooling system. The half-section above the axis of rotation shows the looped air circulation in the enclosed space formed by the housing 110 and the closing flange 111. The half-section below the axis of rotation shows the cooling device 300 for the stators 120, 130, as it also contributes to cooling the air circulating in the enclosed space formed by the housing 110 and the closing flange 111.

[0100] The cooling of the air passing inside the discoid rotor 1 is achieved by a double heat exchange: • with the ambient air outside the machine 100 by following the fabrics of the casing 110 and the closing flange 111; • with the coolant from the stators 120,130 along the radial fins 125a,135a of the covers 125,135 of the frames 121,131.

[0101] The air expelled from the annular chamber 10c of the discoid rotor 1, through the air outlet openings 21 along the path 63, makes the following symmetrical loops: • along the paths 70a, splits into two flows; • according to route 70b, cross the carcasses 121,131 in passages premises 121d, 13 Id made by material removal; • according to paths 70c, bypasses stators 120,130 between the periphery of the stators and the casing fabric 110; • according to the paths 70d, it moves towards the center of the machine 100, housing, on one side, the radial fins 125a of the cover 125 and the casing fabric 110 and on the other side, the radial fins 135a of the cover 135 and the fabric of the closing flange 111; • according to the 70th path, bypasses the 120,130 stators in their internal openings; • is re-aspirated, according to path 60 through the air inlets 17a 1,17b 1 of the discoid rotor 1.

[0102] During the 70d paths, the cooling device 300 of the stators 120,130 therefore participates in the cooling of the air circulating in the annular chamber 10c of the discoid rotor 1.

[0103] The cooling of the stators, and therefore of the covers 125,135, is achieved by the circulation of a liquid in the unoccupied space in the stator chambers 127,137 by being in contact with the coils 123,133 and the yokes 124,134.

[0104] The liquid arrives via a conduit 301 carried by the central spacer 140 and then, via a radial conduit 302 in the spacer, feeds the axial conduits 303 in the external axial extensions 121b,131b of the frames 121,131.

[0105] An opening 304 at the end of the axial conduits 303 allows the liquid to enter the stator chambers 127,137.

[0106] An equivalent device disposed on the electrical machine 100, diametrically opposite to this one (not shown) allows the liquid to be evacuated to an external circuit comprising an exchanger.

Claims

Demands

1. Wound disc rotor (1) for axial magnetic flux electric machine (100) consisting of: • of two flanges (10a, 10b) made of composite material and a steel band (20), assembled by two sets of rivets (50,51) and forming an annular chamber (10c); • of rotor cores (30), in even number, supported at each end by the flanges (10a, 10b), and each carrying a coil (40) arranged in the annular chamber (10c); • of two collectors (41,42) connected one to the end of the wire (40a) of each coil (40) and the other to the end of the wire (40b) of each coil; • of two electrical power supply wires (43, 44), one connected to the external collector (41), the other to the internal collector (42), characterized in that: • each flange (10a, 10b) is pierced with inclined air inlet ducts (17a, 17b) close to the inner diameter (lOd) of the annular chamber (10c), connecting this annular chamber with the ambient internal space of the electrical machine (100) contained in the casing (110) closed by the closing flange (111); • the ring (20) has air outlet openings (21) creating a second communication between the annular chamber (10c) and the ambient internal space of the electrical machine (100) contained in the casing (110) closed by the closing flange (111), creating, during the rotation of the discoid rotor, a flow of cooling air for coils (40) entering through the inclined air inlet ducts (17a, 17b) and exiting through the air outlet openings (21).

2. Wound disc rotor (l) according to claim 1 characterized in that the rotor cores (30), which conduct the magnetic fields generated by the coils and also those generated by the stator pads, are made of SMC (30a), or are a stack of thin sheets electrically insulated from one another, of several widths to form a figure close to a trapezoid and arranged horizontally (30b), or are a bundle of wires of electrically insulated irons tangent to each other (30c).

3. Wound discoid rotor (l) according to claim 1 characterized in that the rotor cores (30) are externally covered with an overmolding (31) of electrical insulating material over their entire length and in two distinct thicknesses: • the thicker one (31b), in the center, serves as a cradle for a coil (40) and axially holds the rotor core (30) because its external dimensions are greater than those of the trapezoidal type openings (1a), (11b) in the flanges (10a, 10b) and its length is equal to the width of the annular chamber (10c); • the thinner (31a) at each end gives the rotor core (30) the same external dimensions as the trapezoidal type openings (lia),(11b) in the flanges (10a, 10b) and its length is equal to the local thickness of the flange fabric, so that the face of the core is flush with the outer surface of the flange on the air gap side.

4. Wound disc rotor (l) according to claim 1 characterized in that all the ends of the wires (40a) of the coils (40) are attached to the outer commutator (41) and all the ends of the wires (40b) of the wire of the coils (40) are attached to the inner commutator (42), which means that the coils are connected in parallel and in order for the identical coils to produce, alternately, magnetic fields of opposite direction, two connections of the ends of the wires (40a) are adjacent between two consecutive coils, alternating with two adjacent connections of the ends of the wires (40b).

5. A wound disc rotor (l) according to claim 1 characterized in that the inclined air ducts (17a, 17b) communicate with the ambient space of the machine via the air inlets (17a1, 17b1), and communicate with the annular chamber (10c) via the air outlets (17a2, 17b2) located below each coil (40). The inclination of the holes is such as to favor the entry of air into the annular chamber when the disc rotor rotates in the main direction, i.e., if the machine is fitted to a motor vehicle, the forward motion of the latter, the air inlets (17a1, 17b1) are angularly ahead of the air outlets (17a2, 17b2).

6. Wound disc rotor (l) according to claim 1 characterized in that the air outlet openings (21) in the hoop (20) are located opposite each coil (40), that the cooling airflow in the annular chamber (lOc) is then as follows: • aspiration through the air inlets (17a 1,17b 1) and expulsion through the air outlets (17a2,17b2) according to the path (60); • the incoming flows are divided at the bottom of the reels (40), equally or not, and bypass them according to the paths (61,62); • the two flows regroup at the top of each coil into one which exits the annular chamber (10c) through the air outlet opening (21) along the path (63).

7. A wound disc rotor (1) according to the preceding claims, characterized in that it forms part of an axial flux electrical machine (100) contained within an enclosed space consisting of a housing (110) and a closing flange (111), allowing the airflow exiting the rotor through the air outlet openings (21) to be cooled in the ambient space of the machine, whose stators (120, 130) are cooled by a circulating liquid cooling device (300). From the air outlet openings (21), along the path (63), the air forms the following symmetrical loops: • depending on the routes (70a), it is divided into two flows; • depending on the routes (70b), cross the carcasses (121,131) in local passages (12Id, 13Id) made by local removals of material; • according to the paths (70c), bypasses the stators (120,130) between the periphery of the stators and the casing fabric (110); • according to the paths (70d), it moves towards the center of the electric machine (100) housing, on one side the radial fins (125a) of the cover (125) (in contact with the coolant of the stator (120)) and the casing fabric (110) and on the other side the radial fins (135a) of the cover (135) (in contact with the coolant of the stator (130)) and the fabric of the closing flange (111); • depending on the routes (70th), bypasses the stators (120,130) in their inner openings; is re-aspirated, along path (60) through the inclined air inlet ducts (17a, 17b) of the discoid rotor (1).

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