Electric powertrain with a single axial magnetic flux motor comprising a single stator, and two independent lateral rotors driving two reducers.

Abstract

Powertrain 10 consisting of a central axial magnetic flux electric machine comprising a single central stator 100, two lateral discoid rotors 200a, 200b and two discoid yokes 300a, 300b for closing the magnetic circuit, and two lateral reduction gears 400a, 400b driven by the discoid rotors, characterized in that the two rotors 200a, 200b are wound and independently controlled, providing traction in case of poor adhesion and torque vectoring control in corners. Figure for the abbreviation: Fig. 1

Description

Title of the invention: Electric powertrain with a single axial magnetic flux motor comprising a single stator, and two independent lateral rotors driving two reducers. TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates mainly to an axial magnetic flux electric machine.

[0002] More specifically, this machine has a single central stator and two independently speed- and torque-controlled wound rotors, each driving a reduction gear. PRIORITY OF THE TECHNOLOGY

[0003] There are numerous publications disclosing axial flux electric machines. For example, WO2022 / 185403 can be cited in the type of architecture comprising a central stator and two lateral rotors. The two rotors are linked and have magnetic studs. To obtain a motor vehicle powertrain, this type of machine is combined with a gearbox equipped with a differential.

[0004] Driving the two wheels of the same axle of a vehicle independently is advantageous because it provides additional traction benefits, for example: • in the event of poor or loss of grip on one of the wheels; • in turns by creating a pivoting effect of the vehicle through torque vectoring control (less torque sent to the inside wheel in the turn).

[0005] To do this, we can use, as in publication US9387847B2, two electric powertrains, one per wheel. PRESENTATION OF THE INVENTION

[0006] The present invention relates to the independent torque and speed driving of the two wheels of the same axle of a motor vehicle with a single motor with two rotors.

[0007] To remain very compact, the motor in question is axial magnetic flux.

[0008] In order to be able to control the two rotors independently, they must be wound and supplied with single-phase or three-phase alternating current.

[0009] Thus, by varying the frequency, we vary the rotational speed and by varying the current intensity, the torque delivered.

[0010] To achieve this result, each rotor is in a constant axial magnetic flux in direction and variable in intensity.

[0011] This field is generated by a central stator whose coils, in even number, are supplied with direct current, of variable intensity according to the power required.

[0012] Two adjacent stator coils generate a magnetic flux in opposite directions, and magnetic loops are obtained by adding yokes. The discoidal rotors are thus framed by the stator and a yoke.

[0013] Each rotor drives a flat epicyclic gear reducer, each driving a wheel.

[0014] In summary, starting from the single central stator, and going to the left or to the right, we successively stack a discoid rotor, a discoid yoke and finally a flat reducer giving a very compact assembly. DETAILED DESCRIPTION OF THE INVENTION

[0015] 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:

[0016] [Fig.1] is a cross-sectional view of the powertrain.

[0017] [Fig.2] is two cross-sectional views describing the stator.

[0018] [Fig.3] is a front view of the right rotor disc and a BB section of this disc passing through the speed sensor.

[0019] [Fig.4] is a partial cross-sectional view of the powertrain restricted to the right rotor.

[0020] [Fig.5] is a partial cross-sectional view of the powertrain restricted to the two rotors and the relative guidance of one with respect to the other.

[0021] [Fig.6] is a sectional view restricted to the power supply of the right rotor disk.

[0022] [Fig.7] is a partial cross-sectional view of the powertrain restricted to the liquid cooling of the stator and cylinder heads.

[0023] [Fig.8] is a cross-sectional view of the left part of the powertrain describing the airflow inside the space formed by the cylinder head and reducer housings.

[0024] [Fig.9] is a partial front view of the discoid rotor describing the path of the air in the internal space of the rotor disc.

[0025] [Fig. 10] is the description of the reducer arranged on the right.

[0026] [Fig. 1] is a cross-sectional view of the powertrain 10.

[0027] It consists of an axial magnetic flux electric motor arranged in a central position, having two power outputs to two planar epicyclic gear reducers of the same reduction ratio arranged on each side of the motor.

[0028] The engine consists of: • of a single stator 100; • of two rotors 200a (on the left in the cross-section) and 200b (on the right in the cross-section) independent of each other in speed and torque delivered; • of two identical cylinder heads 300a (on the left in the section) and 300b (on the right in the section), whose role is to form the magnetic loops with the stator; • of two housings 310a (on the left in the section) and 310b (on the right in the section) carrying the two cylinder heads 300a,300b and mounted in support on the sides of the stator 100; • of two power supply devices 280a (on the left in the section) and 280b (on the right in the section) for the rotor discs; • of two 400a reducers (on the left in the section) and 400b (on the right in the section) with planar epicyclic gear train of the same reduction ratio arranged on each side of the motor.

[0029] [Fig.2] is two cross-sectional views describing the stator 100.

[0030] Its structure is composed of two flanges 110,111 forming a closed interior space 112.

[0031] The sealing of the internal space 112 is ensured by the O-rings 113,114.

[0032] The two flanges are pressed against each other on the inner diameter by the screws 120 and on the outer diameter by fixing screws with the cylinder head housings 310a,310b (see [Fig.l]) and passing through the two flanges in the holes 121.

[0033] The closed interior space 112 accommodates stator pads 130, of an even number, passing through the walls of the flanges 110,111 and flush with the outer face of the flanges.

[0034] The sealing of the passage through the walls of the flanges 110,111 by the stator pads 130 is ensured by the O-rings 131,132.

[0035] The stator pads have in the central part 133 inside the internal space 112 a size greater than the extreme parts 134 passing through the walls of the flanges, which ensures their axial locking.

[0036] Each stator pad carries a coil 140.

[0037] Between the coil 140 and the stator contact 130 is interposed an electrically insulating sheet 141.

[0038] On the periphery of the coils, the internal space 112 accommodates two circular collectors 150a, 150b.

[0039] Each coil 140 is connected to the two collectors in the following manner, given that the power supply is direct current: • The coils 140 are connected to the collectors by their two ends 140a, 140b of the winding wire; • All 140a ends are soldered to the 150a collector and all 140b ends to the 150b collector. The 140 coils are therefore connected in parallel. • To obtain an alternation of the direction of the magnetic flux of two adjacent coils, which all have the same direction of winding of the wire, we will have, between two coils, two adjacent 140a ends alternating with two adjacent 140b ends.

[0040] the collectors are connected to an external DC power supply by the two conductors 160a, 160b.

[0041] These two conductors 160a, 160b pass through the elastomer pad 116 inserted in the peripheral wall of the flange 111, thus ensuring a watertight passage.

[0042] [Fig.3] is a front view of the disc 210b (the one on the right in [Fig.l]) of the rotor 200b and a section BB of this disc passing through the speed sensor 250. This figure is a front view of the flange 211a.

[0043] The structure of the rotor disc rests on two flanges, 21la,211b in composite material and a steel ring 220 which, as we will see in the description, has three roles.

[0044] The first role of this band 220, on which the flanges can be centered with radial clamping, is to substantially increase the resistance of the flanges to the centrifugal forces generated by the rotor cores 230 which each carry a coil 240 and allow a higher limiting rotational speed.

[0045] The two flanges 21a, 211b and the rim are joined by two sets of rivets, internally 214 (the two flanges only) and externally 215 (the two flanges with the rim). Each set has a number equal to that of the rotor cores 230.

[0046] The flanges have a central opening 212a,212b for centering on the carrier hub (see [Fig.4]).

[0047] On a slightly larger diameter, we have a series of holes. These are the screw holes 213a for fixing the discoid rotor 1 and the pin holes 213b for contributing to the transmission of torque.

[0048] The two flanges 21la,211b and the rim 220 form an annular chamber 21le, for receiving the rotor cores 230, each carrying a coil 240.

[0049] On a diameter greater than that of the rivets 214, we have a series of inclined holes 216b which connect the annular chamber 211c with the interior space of the electrical machine.

[0050] These holes 216b allow the passage of a cooling airflow from the coils 240 from the inlet 216bl to the outlet 216b2 in the chamber 21le. The outlets 216b2 are centered with respect to the median axis of the coils.

[0051] Air is expelled from the annular chamber 211c through the peripheral openings 221 in the band 220, also positioned in the median plane of the coils. This is the second role of this band.

[0052] In flange 21 there are no openings equivalent to the bores 216b because they would not be supplied with air: see the rotor cooling airflow [Fig. 8]. Note that the air inlet ducts will only be effective for the direction of rotation 201 (inlet 216bl is ahead of outlet 216b2). For an electric motor equipping a vehicle, this direction of rotation must correspond to forward motion.

[0053] Each flange has two trapezoidal type openings 217a,217b, the number of which is always even but varies according to the performance required for the electric machine, which carry one end of the rotor cores 230.

[0054] The central part of the annular chamber 21, accommodates two closed circular collectors 241, 242.

[0055] They are connected to each end of the winding wire of the coils 240. All the ends 240a are soldered to the commutator 241 and all the ends of the wire 240b are soldered to the commutator 242. All the coils are thus connected in parallel. Since the windings are in the same direction, all the coils simultaneously produce the same magnetic field in direction and intensity.

[0056] Single-phase AC power supply conductors are welded to the collectors 241 and 242. The power supply wire 243 is attached to the collector 241. The power supply wire 244 is attached to the collector 242. These two conductors pass through the wall of the flange 211b to be connected to the internal power supply device of the electric machine (see [Fig. 6]).

[0057] The rotor 210b (similarly for the rotor 210a), placed in a magnetic field of constant direction, but of variable intensity, delivered by the stator 100, will start rotating as soon as it is supplied with alternating current.

[0058] To control rotational speed and direction of rotation, we need for each rotor (since they are independent) a speed sensor 250 associated with a particular reading track.

[0059] The reading track of this sensor is the steel ring 220, thanks to the openings 221 which are the cooling air outlets and which create discontinuities. This is the third role of the ring 220.

[0060] The openings 221 are distributed regularly around the periphery and, in the embodiment presented, are equal to the number of reels.

[0061] An additional opening 221a is added. If we call the angle between two openings 221 1PAS, the additional opening 221a is arranged at 1 / 3PAS of one opening 221 and at 2 / 3PAS of the next.

[0062] The time between reading two consecutive openings 221 is t.

[0063] At a given rotational speed, the sensor 250 is capable of: • By reading only the 221 openings to give the rotation speed; • By reading the opening 221a (discontinuity of t) to reset the angular orientation of the rotor; • By reading the sequence t,(2 / 3)t,(l / 3)t, t to indicate that the direction of rotation is 201, and by reading the sequence t,(l / 3)t,(2 / 3)t, t to indicate that the direction of rotation is 202.

[0064] [Fig.4] is a partial cross-sectional view of the powertrain 10 restricted to the right rotor 200b.

[0065] The rotor disc 210b is centered on a hub 260b. It is secured by screws 261b bearing against the intermediate one-piece washer 262b.

[0066] In the hollow hub 260b is mounted a sleeve 263b driven in rotation by the splines 263b 1. At the end protruding from the hub, the teeth 263b2 are cut which are those of the planetary gear of the reducer 400b.

[0067] The other end of the sleeve 263b has a collar 263b3 bearing axially on the hub 260b, blocked by the retaining ring 264b. Between the collar 263b3 and the hub 260b, an O-ring 265b is interposed in a groove of the hub.

[0068] The rotor 200b has a sealed ball bearing 266b for guidance in the housing 410b. The latter is positioned and fixed to the housing 310b of the cylinder head 300b.

[0069] A washer 267b interposed between the outer ring of the bearing 266b and the housing 410b axially positions the rotor. The thickness is chosen so that the face of the rotor disc 210b opposite the stator is in the same plane Fb as the face of the housing 310b bearing against the stator.

[0070] [Fig.5] is a partial cross-sectional view of the powertrain 10 restricted to the two rotors 200a,200b and the relative guidance of one with respect to the other.

[0071] Guiding the rotor 200a by the single bearing 266a and the rotor 200b by the single bearing 266b is not sufficient.

[0072] The two hollow hubs 260a,260b accommodate an assembly consisting of a shaft 270 and two double angular contact ball bearings 27la,271b.

[0073] The inner and intermediate rings are in contact and supported on the central shoulder 270a. The washers 272a, 272b and the screws 273a, 273b even under slight preload the two bearings.

[0074] On the left rotor side 200a, an adjusting washer 274 is interposed between the outer ring of the bearing 271a and the hub 260a. Its role is twofold: • to bring to the two housings 310a, 310b, which rest upon the stator 100, the spacing Es equal to the thickness of the stator; • by adding a slight over-thickness, to give the two bearings 266a and 266b a slight preload to obtain an assembly without axial play even during temperature increases.

[0075] To limit the differential expansion effect, the shaft 270 will preferably be made of the same metal as the housings, i.e. aluminium.

[0076] [Fig.6] is a sectional view restricted to the 280b current supply of the 210b right rotor disc.

[0077] It includes a first support element 281b, made of insulating material, for the other elements that make up the device.

[0078] This first support element 281b is centered by its diameter 281b 1 on the hub 260b and is fixed in rotation by the axial notches 281b2.

[0079] On the support element 281b is mounted a complementary element 285b, also made of insulating material and driven in rotation by the grooves 281b3.

[0080] The support element 281b and the complementary element 285b, which are rotationally fixed, frame a rotating fixed element 290b made of insulating material.

[0081] The fixed element 290b in the shape of a crown, is centered on the support element 281b, has an outgrowth 290bl which cooperates with a pin 412b, for locking against rotation, screwed into the housing 410b of the reducer 400b.

[0082] The fixed element 290b, made of insulating material, carries on either side the crown-shaped plates 291b and 292b made of conductive material.

[0083] Similarly, the support elements 281b and complementary elements 285b carry crown-shaped plates 282b, 286b also made of conductive material, opposite respectively the crown-shaped plates 292b and 291b

[0084] Between the crown-shaped plates 282b,292b on the one hand and 286b,291b on the other hand are intercalated identical transmitting discs 293, the first centered by its outer diameter in the support element 281b, the second centered by its outer diameter in the complementary element 285b, and free to rotate.

[0085] These two transmitting discs 293 are similar to those of needle bearings, but play a very different role. They are composed of an annular disc 294 made of insulating material which has, on two concentric circles, a large number of rectangular openings in which are inserted cylindrical and identical rollers 295 made of conductive material, copper or copper alloy, with a diameter greater than the thickness of the annular disc 294.

[0086] These rollers are subjected to a very low axial load which ensures the contact of the greatest possible proportion of rollers 295 with on the one hand the crown-shaped plates 282b,292b and on the other hand the crown-shaped plates 286b,291b in order to transmit the electric current from the fixed element 290b, connected to an external power supply, to the support element 281b and the complementary element 285b in rotation, connected to the coils of the rotor disc 210b.

[0087] For this purpose, the complementary element 285b, the fixed element 290b, and the transmitting disks 293 are pressed against each other and against the element support 281b by a spring of type wave washer 296, mounted in a circular groove of the complementary element 285b, put under tension by the washer 297 held by the stop ring 298 engaged in a groove of the support element 281b.

[0088] The choice of a very large number of rollers 295 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.

[0089] The crown-shaped plates 286b, 282b have tabs 286b1 and 282b1 for connection with the rotor coils. In the embodiment described in [Fig. 6], tab 286b1 is welded to the supply wire 244 of the commutator 242, and tab 282b1 is welded to the supply wire 243 of the commutator 241.

[0090] The crown-shaped plates 291b,292b carried by the fixed element 290b each have a tab 291bl,292bl for connection with the external power supply device (not shown) by the cable 299b.

[0091] To ensure the longevity of the power supply device 280b, the rollers 295 will be coated with conductive grease. This grease will be retained confined by the felt seals 283, 287.

[0092] [Fig.7] is a partial cross-sectional view of the powertrain 10 restricted to the liquid cooling of the stator 100 and the cylinder heads 300a,300b.

[0093] Liquid cooling in contact with the elements subject to heating, either by Joule effect (the coils) or by eddy current induced (metallic elements conducting the magnetic field: stator core, yoke) is essential for the electrical machine to be able to deliver a high continuous power.

[0094] The single central stator 100 has a structure comprising two flanges 110,111 made of composite material forming a sealed internal space 112.

[0095] This enclosed space houses the stator pads 130, the coils 140, and the commutators 150a, 150b, which are subject to significant heating (see [Fig. 2]). Indeed, the stator contributes most of the machine's power, which means that the coils carry high currents.

[0096] The cooling of the stator 100 is therefore provided by liquid in direct contact with the coils 140 and the collectors 150a,150b.

[0097] The coolant enters the internal space 112 through the nozzle 117. This entry point is preferably located in the upper part of the machine. The liquid passes around and between the coils and exits the chamber through the nozzle 118.

[0098] on each side of the stator 100 rest the housings 310a and 310b which carry the cylinder heads 300a, 300b.

[0099] The rear face of the cylinder head 300a,300b is in annular support on the housing 310a,310b.

[0100] Between the outer and inner annular supports of the cylinder heads 300a,300b, the crankcase 310a,310b forms a liquid circulation chamber 3lia,311b. This chamber is sealed by the outer O-rings 30la,301b and inner O-rings 302a,302b.

[0101] The cylinder head coolant 300a enters the chamber 311a through the nozzle 314a and via the communication bore 312a.

[0102] The cylinder head coolant 300a exits the chamber 311a through the nozzle 315a and via the communication bore 313a.

[0103] Similarly, the cylinder head coolant 300b enters chamber 311b through nozzle 314b and via communication bore 312b, and exits chamber 311b through nozzle 315b and via communication bore 313b.

[0104] [Fig.8] is a cross-sectional view of the left part of the powertrain 10 describing the airflow inside the space formed by the cylinder head housings 310a and the reducer housing 410a.

[0105] Filtered air is pulsed into this space by nozzle 320a.

[0106] In the closed volume the air follows the path 50 between the radial walls of the housings 310a and 410a.

[0107] After bypassing the housing 310a in its central opening 51, two paths are possible. The first 52 is to enter the annular chamber 21 of the rotor disc 210a through the inclined holes 216a. The second is to pass through the air gap between the cylinder head 300a and the rotor disc 210a along the path 60.

[0108] The two flows, grouped at the periphery of the rotor disc, exit the internal space through the openings 321a, bores in the housing 310a along the path 70.

[0109] [Fig.9] is a partial front view of the discoid rotor 210a describing the path of the air in the annular chamber 21 le.

[0110] On the flange 211b, below each coil 240, that is to say in the part closest to the axis of rotation, we have a bore 216b inclined with respect to the axis of rotation of the discoid rotor 210a.

[0111] This bore is an air circulation conduit between the internal volume formed by the cylinder head housing 310a and the reducer housing 410a and the internal unoccupied volume of the annular chamber 211c.

[0112] For the direction of rotation 201 indicated, the introduction of air towards the annular chamber 21 le is facilitated by an air inlet 216bl, which is angularly ahead of the air outlet 216b2. The air outlet 216b2 is centered with respect to the coil 240.

[0113] In the ring 220, the air outlet openings 221 are, conversely, an air circulation duct from the annular chamber 211c to the internal volume of the housings. The openings are centered with respect to the coils 240.

[0114] Thus, the air circulation between the drillings 216b and the air outlet openings 221 of the annular chamber 21 is as follows: • aspiration through air inlets 216bl and expulsion through air outlets 216b2 of the holes 216b inclined along the path 52; • the incoming flows are divided at the base of the 240 coils, equally or not, and bypass them according to the paths 53,54; • the two flows regroup at the top of each coil and exit the annular chamber 21 through the air outlet opening 221 along the path 55.

[0115] The electric machine with two independent rotors transmits its power to two reducers 400a, 400b arranged at the ends of the powertrain.

[0116] [Fig. 10] is the description of the 400b reducer arranged on the right.

[0117] In the closed, sealed space formed by the housing 410b and the cover 411b is arranged an epicyclic train 420. The epicyclic trains are identical in each reducer.

[0118] The train consists of: • of a cylindrical planetary gear, with helical teeth 263b2, at the end of the sleeve 263b guided and driven in rotation by the hub 260b of the right discoid rotor; • of a satellite carrier body 421, three satellites 422, conventionally guided on points and axes 423 held at its two ends by the satellite carrier body 421 and a reinforcing plate 424; • of a fixed rotating crown 425 shrink-fitted in the housing 410b and provided with axial inlay notches 425a in the housing; • A ball bearing 430 for guiding and axially retaining the satellite carrier 421.

[0119] The movement and torque of the electric machine enters through the helical teeth 263b2 and exits through the splines 421b of the hub 421a of the planet carrier 421.

[0120] The enclosed space, formed by the housing 410b and the cover 411b, is made watertight by: • The dynamic joint 431 between the hub 421a of the satellite carrier and the cover 411b; • the operculum 432 obstructing the hub of the satellite carrier 421a; • the dynamic joint 268b between the hub 260ba of the right discoid rotor and the housing 410b.

[0121] The planetary gear train is lubricated by oil.

[0122] It is poured into the space formed by the housing 410b and the cover 411b by the filler cap 440.

[0123] Draining is carried out via plug 450.

[0124] The latter carries a magnet 451 which will capture all the fine ferrous particles released by the break-in and wear.

[0125] the filler cap carries a valve 441 for balancing the pressure between the internal volume consisting of the housing 410b and the cover 411b and the external environment.

Claims

Demands

1. Powertrain (10) consisting of a central axial magnetic flux electric machine comprising a single central stator (100), two lateral discoid rotors (200a, 200b) and two discoid yokes (300a, 300b) for closing the magnetic circuit, and two lateral reduction gears (400a, 400b) driven by the discoid rotors, characterized in that the two rotors (200a, 200b) are of the wound type, independent of each other in terms of speed and torque delivered, in order to provide the vehicle with better traction performance in case of poor grip and torque vectoring control in corners.

2. Powertrain (10) according to claim 1 characterized in that the stator (100) has an even number of coils (140), carried by stator pads (130), and that they are supplied by a direct electric current.

3. Powertrain (10) according to claim 2 characterized in that the coils (140) of the stator (100) are connected in parallel and that in order to obtain an alternation of the direction of the magnetic flux of two adjacent coils, which all have the same direction of winding of the wire, we will have, between two coils, two adjacent ends (140a) alternating with two adjacent ends (140b).

4. Powertrain (10) according to claim 1 characterized in that the coils (240) of the discoid rotors (200a,200b) are supplied with single-phase alternating current.

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