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

Abstract

Power unit 10 consisting of a central electrical machine with axial magnetic flux 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 reducers 400a, 400b driven by the discoid rotors, characterized in that the two rotors 200a, 200b are of the wound type and controlled independently providing traction performance in the event of poor grip and torque vector control when cornering. Figure for the abstract: 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 mainly relates to an axial magnetic flux electric machine.

[0002] More precisely, this machine has a single central stator and two wound rotors with independent speed and torque control, each driving a reducer. STATE OF THE ART

[0003] There are many publications disclosing an axial flux electric machine. In the type of architecture comprising a central stator and two lateral rotors, one can cite as an example publication WO2022 / 185403. The two rotors are linked and carry magnetic pads. To obtain a motor vehicle powertrain, this type of machine is associated with a reducer equipped with a differential.

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

[0005] To do this, it is possible to use, as in publication US9387847B2, two electric powertrains, one per wheel. PRESENTATION OF THE INVENTION

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

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

[0008] 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 rotation speed and by varying the intensity of the current the torque delivered.

[0010] To achieve this result, each rotor is in an axial magnetic flux constant 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 coils of the stator generate a magnetic flux in opposite directions and the magnetic loops are obtained by adding yokes. The discoid rotors are therefore framed by the stator and a yoke.

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

[0014] In summary, starting from the single central stator, and going towards the left or towards 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 characteristics, aims and advantages of the present invention will appear on reading the detailed description which follows and with regard to the appended drawings given as non-limiting examples and in which:

[0016] [Fig.l] is a sectional view of the powertrain.

[0017] [Fig.2] is two 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 sectional view of the powertrain restricted to the right rotor.

[0020] [Fig.5]is a partial 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 sectional view of the powertrain restricted to the liquid cooling of the stator and cylinder heads.

[0023] [Fig.8]is a sectional view of the left part of the power unit describing the air circulation inside the space formed by the cylinder head and reduction gear 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 sectional view of the powertrain 10.

[0027] It is composed of an axial magnetic flux electric motor arranged in a central position, equipped with two power outputs to two planetary gear reducers with the same gear ratio arranged on each side of the motor.

[0028] The engine is composed of: • a single stator 100; • two rotors 200a (on the left in the section) and 200b (on the right in the section) independent of each other in speed and torque delivered; • two identical yokes 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; • two casings 310a (on the left in the section) and 310b (on the right in the section) carrying the two cylinder heads 300a, 300b and mounted to rest on the sides of the stator 100; • two current supply devices 280a (on the left in the section) and 280b (on the right in the section) for the rotor discs; • two reducers 400a (on the left in the section) and 400b (on the right in the section) with a flat epicyclic gear train of the same gear ratio arranged on each side of the motor.

[0029] [Fig.2] is two 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 interior 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 outside diameter by screws securing them to 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 interior space 112 a size greater than the end 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 pad 130 is interposed an electrically insulating sheet 141.

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

[0039] Each coil 140 is connected to the two collectors in the following manner, taking into account 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 ends 140a are soldered to collector 150a and all ends 140b to collector 150b. The coils 140 are therefore connected in parallel. • To obtain an alternation of 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.

[0040] the collectors are connected to an external direct current 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 sealed crossing.

[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 is based on two flanges, 211a, 211b made of composite material and a steel ring 220 which, as we will see in the description, has three roles.

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

[0045] The two flanges 211a, 211b and the ring are secured by two series of rivets, internally 214 (the two flanges only) and externally 215 (the two flanges with the ring). Each series 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 drillings. These are the screw passage holes 213a for fixing the discoid rotor 1 and the pin passage holes 213b contributing to the transmission of the torque.

[0048] The two flanges 211a, 211b and the ring 220 form an annular chamber 211c, 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 put the annular chamber 211c into communication with the interior space of the electric machine.

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

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

[0052] In the flange 211a there are no openings equivalent to the holes 216b because they would not be supplied: see the rotor cooling air flows [Fig.8]. Note that the air inlet ducts will only be effective for the direction of rotation 201 (the inlet 216bl is ahead of the outlet 216b2). This direction of rotation, for an electric machine fitted to a vehicle, must be that corresponding to forward motion.

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

[0054] The central part of the annular chamber 21 1e 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 collector 241 and all the ends of the wire 240b are soldered to the collector 242. All the coils are thus connected in parallel. The windings being in the same direction, all the coils simultaneously produce the same magnetic field in direction and intensity.

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

[0057] The rotor 210b (same 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 the rotation speed and direction, 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, equal to the number of coils.

[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 from one opening 221 and at 2 / 3PAS from the next.

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

[0063] At a given rotation speed, the sensor 250 is capable of: • By reading the only openings 221 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 indicates that the direction of rotation is 201, and by reading the sequence t,(l / 3)t,(2 / 3)t, t indicates that the direction of rotation is 202.

[0064] [Fig.4] is a partial 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 the screws 261b bearing on the intermediate single-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 extending beyond 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 axially supported on the hub 260b, blocked by the stop ring 264b. Between the collar 263b3 and the hub 260b is interposed in a groove of the hub a sealing O-ring 265b.

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

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

[0070] [Fig.5] is a partial 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 bearing 266a alone and the rotor 200b by the bearing 266b alone 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 rings and the intermediate rings are in contact and rest on the central shoulder 270a. The washers 272a, 272b and the screws 273a, 273b even slightly 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: • bring to the two casings 310a, 310b, which come to bear on the stator 100, the spacing Es equal to the thickness of the stator; • by adding a slight excess 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 casings, i.e. aluminum.

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

[0077] It comprises a first support element 281b, made of insulating material, from the other elements which make up the device.

[0078] This first support element 281b is centered by its diameter 281b 1 on the hub 260b and is rotationally secured 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, integral in rotation, frame a fixed element 290b in rotation, made of insulating material.

[0081] The fixed element 290b in the form of a crown, is centered on the support element 281b, has a protrusion 290bl which cooperates with a pin 412b, for locking in rotation, screwed into the casing 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 285b carry crown-shaped plates 282b, 286b also made of conductive material, facing 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 interposed identical transmitter discs 293, the first centered by its external diameter in the support element 281b, the second centered by its external diameter in the complementary element 285b, and free to rotate.

[0085] These two transmitting discs 293 are similar to those of the needle thrust 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 quantity of rectangular openings in which are inserted rollers 295, cylindrical and all identical, 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 largest 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 electrical supply, to the support element 281b and the complementary element 285b in rotation, connected to the coils of the rotor disk 210b.

[0087] For this, the complementary element 285b, the fixed element 290b, as well as the transmitting discs 293 are pressed against each other and against the element support 281b by a wave washer type spring 296, mounted in a circular groove of the complementary element 285b, tensioned 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 of splitting the electric current and limiting it, for each contact, to a low intensity level reducing the risks of electric arcing and damage.

[0089] The crown-shaped plates 286b, 282b have tabs 286b 1 and 282b 1 for connection with the rotor coils. In the embodiment described by this [Fig.6], the tab 286bl is welded to the supply wire 244 of the collector 242, and the tab 282b 1 is welded to the supply wire 243 of the collector 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 current supply device (not shown) by the cable 299b.

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

[0092] [Fig.7] is a partial 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 elements subject to heating, either by Joule effect (coils) or by induced eddy current (metallic elements conducting the magnetic field: stator core, yoke) is essential for the electrical machine to be able to deliver high continuous power.

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

[0095] This closed space houses the stator pads 130, the coils 140, the collectors 150a, 150b subject to significant heating (see [Fig.2]). Indeed, the stator contributes to the majority of the power of the machine, which means that the coils are traversed by high intensity currents.

[0096] 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 interior space 112 through the nozzle 117. This entry point will preferably be 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 casings 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 casing 310a, 310b.

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

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

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

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

[0104] [Fig.8] is a sectional view of the left part of the power unit 10 describing the air circulation inside the space formed by the casings 310a of the cylinder head and 410a of the reducer.

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

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

[0107] After bypassing 51 the casing 310a in its central opening, 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 disk, exit the internal space through the openings 321a, holes in the casing 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 211e.

[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 relative to the axis of rotation of the discoid rotor 210a.

[0111] This drilling is an air circulation duct between the internal volume formed by the casings 310a of the cylinder head and 410a of the reducer 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 211c is favored by an air inlet 216bl, angularly in advance of the air outlet 216b2. The air outlet 216b2 is centered relative to the coil 240.

[0113] In the hoop 220, the air outlet openings 221 are conversely an air circulation duct from the annular chamber 211c to the volume internal to the casings. The openings are centered relative to the coils 240.

[0114] Thus, the circulation of air between the holes 216b and the air outlet openings 221 of the annular chamber 21c is as follows: • suction through the air inlets 216bl and expulsion through the air outlets 216b2 of the holes 216b inclined along the path 52; • the incoming flows are shared at the base of the coils 240, equally or not, and bypass them along the paths 53,54; • the two flows come together 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 reducer 400b arranged on the right.

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

[0118] The train is made up 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; • a planet carrier body 421, three satellites 422, conventionally guided on needles and axes 423 held at its two ends by the body of the planet carrier 421 and a reinforcement plate 424; • a fixed rotating crown 425, shrunk into the casing 410b and provided with axial inlay notches 425a in the casing; • A 430 ball bearing for guiding and axially holding the 421 planet carrier.

[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 closed space, constituted by the casing 410b and the cover 411b is made watertight by: • The dynamic seal 431 between the hub 421a of the planet carrier and the cover 411b; • the cover 432 obstructing the hub of the planet carrier 421a; • the dynamic seal 268b between the hub 260ba of the right disc rotor and the casing 410b.

[0121] The planetary gear is lubricated by oil.

[0122] It is poured into the space formed by the casing 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 running-in and wear.

[0125] the filling cap carries a valve 441 balancing the pressure between the internal volume constituted by the casing 410b and the cover 411b and the external environment.

Claims

Claims

1. Powertrain (10) consisting of a central electrical machine with axial magnetic flux comprising a single central stator (100), two lateral discoid rotors (200a, 200b) and two discoid yokes (300a, 300b) for looping the magnetic circuit, and two lateral reducers (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 speed and torque delivered in order to provide the vehicle with better traction performance in the event of poor grip and torque vector control when cornering.

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 powered 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 to obtain an alternation of 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. Power unit (10) according to claim 1 characterized in that the coils (240) of the discoid rotors (200a, 200b) are supplied with single-phase alternating current.

Images