ROTATING MAGNETIC FIELD BRAKING DEVICE, BRAKED WHEEL AND CORRESPONDING AIRCRAFT.

Abstract

Magnetic braking device comprising at least one stator (2) and at least one rotor (3), and electromagnets (5) secured to the rotor and / or the stator to produce between them, when the rotor rotates, at least one magnetic field capable of generating eddy currents braking the rotor. According to the invention, the device comprises at least one control unit (7) capable of controlling an alternating electrical power supply of at least some of the electromagnets so that the magnetic field is a rotating magnetic field, the control unit being configured to adapt a rotation speed of said magnetic field as a function of at least one data characteristic of the rotation speed of the rotor 1 by acting on at least one of the parameters of the electrical power supply of at least one of the electromagnets. FIGURE OF THE ABSTRACT: Fig. 3

Description

Title of the invention: ROTATING MAGNETIC FIELD BRAKING DEVICE, BRAKED WHEEL AND CORRESPONDING AIRCRAFT.

[0001] The present invention relates to a rotating magnetic field braking device.

[0002] The present invention relates to a braked wheel comprising such a device as well as an aircraft equipped with such a wheel.

[0003] BACKGROUND OF THE INVENTION

[0004] An aircraft wheel generally comprises a rim surrounded by a tire and connected by a web to a hub mounted to rotate on a wheel support shaft (axle or spindle).

[0005] Friction braking devices are known comprising a stack of braking discs which is housed in an annular space extending between the rim and the hub and which comprises an alternation of rotor discs linked in rotation with the wheel and stator discs fixed relative to the wheel support shaft. The braking device also comprises hydraulic or electromechanical actuators mounted on an actuator holder and arranged to apply a pressing force on the stack of discs so as to generate a braking torque to brake the rotation of the wheel.

[0006] Eddy current magnetic braking devices are also known, used for braking vehicle wheels and more particularly aircraft wheels. These devices often comprise a rotor connected in rotation to the wheel, a stator which surrounds the rotor and which is connected in rotation to the wheel support shaft and free in translation relative to said shaft, permanent magnets for producing an axial magnetic flux between the stators and the rotor, and linear actuators for axially moving the stator between a maximum braking position in which the stator is close to the rotor and a free rotation position in which the stator is far from the rotor.

[0007] These magnetic braking devices have the disadvantage of being very ineffective when the wheel is rotating at low speed.

[0008] SUBJECT OF THE INVENTION

[0009] The invention aims in particular to propose a device for braking a wheel which is more efficient over a wider range of rotational speeds of said wheel. Summary of the invention

[0010] To this end, according to the invention, a magnetic braking device is provided comprising at least one stator and at least one rotor and electromagnets secured to the rotor and / or the stator to produce between them, when the rotor rotates, at least one magnetic field capable of generating eddy currents braking the rotor.

[0011] According to the invention, the device comprises at least one control unit capable of controlling an alternating electrical power supply of at least some of the electromagnets so that the magnetic field is a rotating magnetic field, the control unit being configured to adapt a rotation speed of said magnetic field as a function of at least one data item characteristic of the rotation speed of the rotor by acting on at least one of the parameters of the electrical power supply of at least one of the electromagnets.

[0012] Thanks to the adaptation of the rotational speed of the magnetic field, the invention proves to be effective even for low rotational speeds of a wheel associated with such a braking device. In particular, the braking performance of the magnetic braking device is no longer (or significantly less) dependent on the rotational speed of the rotor.

[0013] Optionally, the stator and the rotor are arranged so that the magnetic flux is an axial magnetic flux.

[0014] Optionally, the braking device comprises two stators surrounding the rotor.

[0015] Optionally, the braking device comprises a metal part, the rotor being arranged between the stator and said metal part allowing the magnetic field to be closed.

[0016] Optionally, the electromagnets are all integral with the stator.

[0017] Optionally, the electromagnets are arranged at regular intervals on the stator.

[0018] Optionally, the stator has openings each receiving one of the electromagnets, each of said electromagnets having a flange abutting against one or more walls of the stator forming the associated opening.

[0019] Optionally, the electromagnets are divided into N groups, each group comprising at least one electromagnet and each of the N groups comprising the same number of electromagnets, the alternating current power supply being an alternating current power supply comprising N phases, each group of electromagnets being associated with a respective one of said phases.

[0020] Optionally, the parameter on which the control unit acts is a phase of the alternating electrical power supply associated with at least one electromagnet.

[0021] Optionally, the control unit is configured to adapt a rotation speed of said magnetic field also as a function of a desired braking torque, in a braking torque range from zero to a maximum braking torque that can be generated by the braking device.

[0022] Optionally, the braking device can be used in a motor mode providing motor torque to the rotor.

[0023] The invention also relates to a braked wheel comprising a braking device as mentioned above.

[0024] The invention also relates to an aircraft comprising a braked wheel as mentioned above.

[0025] Other characteristics and advantages of the invention will emerge from reading the following description of a particular and non-limiting embodiment of the invention. Brief description of the drawings

[0026] Reference will be made to the accompanying drawings, among which:

[0027] [Fig-1] [Fig.l] is a partial schematic front view of an aircraft equipped of landing gear according to the invention;

[0028] [Fig.2] [Fig.2] is a schematic partial view of an assembly of a wheel and a shaft carrying the wheel according to a particular embodiment of the invention, in axial half-section;

[0029] [Fig.3] [Fig.3] is a perspective view of part of the assembly illustrated in [Fig.2] ;

[0030] [Fig.4] [Fig.4] is a block diagram illustrating the control of a device of magnetic braking of the wheel illustrated in [Fig.2];

[0031] [Fig.5] [Fig.5] is a graph representing the braking torque of a device of braking of the prior art as a function of a rotation speed of the rotor of said device. DETAILED DESCRIPTION OF THE INVENTION

[0032] With reference to Figures 1 to 3, the braking system according to the invention is carried by an aircraft 100 comprising landing gears 101. Each landing gear 101 comprises a leg having one end provided with two coaxial shafts 102, each shaft 102 having a central axis defining an axis X of rotation of the wheel 103 which it carries.

[0033] Each wheel 103 comprises, in a manner known per se, a hub 104 mounted to pivot on the shaft 102 and a rim 105 connected to the hub 104 by a web 106. The rim 105 and the hub 104 define between them an annular space having one end closed by the web 106 and one end open towards the outside of the wheel 103. The rim 105 is surrounded by a tire not shown.

[0034] At least one of the wheels 103 is equipped with a magnetic braking device generally designated 1.

[0035] The magnetic braking device 1 extends for example in the annular space introduced above.

[0036] The magnetic braking device 1 here comprises at least one fixed element, or stator 2, and at least one mobile element, or rotor 3. In the present case, the device magnetic braking system 1 comprises several fixed elements, or stators 2, and a single rotating mobile element, or rotor 3. More precisely, there are two stators 2.

[0037] In the present case, the rotor 3 is arranged between the two stators 2.

[0038] More precisely here the stators 2 and the rotor 3 are in the form of crowns. preferably, the stators 2 and the rotor 3 are arranged so as to be coaxial with the wheel 103 and the shaft 102.

[0039] The main faces of the rotor 3 and of the two stators 2 thus extend parallel to each other and to a plane defined by a second axis Y (orthogonal to the first axis X) and by a third axis Z (orthogonal to the first axis X and to the second axis Y).

[0040] The stators 2 are here the parts of the device linked in rotation to the shaft 102. Optionally the stators 2 are linked to the shaft 102 by means of a torque tube 4 which extends coaxially to the shaft 102. The torque tube 4 is for example fixed (for example by at least one screw 6) to an external collar 102' of the shaft 102. The torque tube 4 is thus integral in rotation with the shaft 102 around the axis X. The stators 2 are themselves fixed to the torque tube 4. For example the stators 2 are linked to the torque tube by means of bars extending in projection towards the inside of the torque tube 4.

[0041] Furthermore, the rotor 3 is connected in rotation to the wheel 103 either directly or by means of at least one intermediate part (such as for example the rim, the hub, etc.). The rotor 3 is made of electrically conductive material. The rotor 3 is for example made of metallic material and for example copper, aluminum, silver, nickel, etc.

[0042] In operation, the rotor 3 rotates on itself around its central axis (the X axis) relative to the stator 2.

[0043] It is therefore understood that each of the two stators 2 is linked in rotation to the torque tube 4 which is itself linked in rotation to the shaft 102. These two disc-shaped stators 2 are parallel to each other and are positioned on either side of the rotor 1 which is also disc-shaped, the rotor 1 being arranged coaxially and parallel to said stators 2.

[0044] The two stators 2 are here identical to each other. In this way, the following description of one of the stators 2 is also applicable to the other of the stators 2.

[0045] The stator 2 comprises a non-magnetic support which is shaped like a crown. Said support is provided with a plurality of electromagnets 5 (only a part of which is referenced in [Fig. 3]) integral with the stator 2. These electromagnets 5 are arranged at regular intervals on the stator 2.

[0046] The stator 2 has a plurality of openings so that in each opening one of the electromagnets 5 is received. It is therefore understood that the openings are also arranged at regular intervals all around the stator 2. In the present case, each opening passes through the stator 2 so as to open at a first end onto the first main face 2a of the stator 2 and to open at a second end onto the second main face 2b of the stator 2. Each opening thus extends axially in the stator 2 considered. Each opening thus extends parallel to the axis X.

[0047] When an electromagnet 5 is arranged in an opening, it protrudes from at least one of the sides of the stator 2 and in the present case from both sides of the stator 2. Each electromagnet 5 thus has an active surface which extends into the air gap defined by the associated stator 2 and the facing rotor 3. It is therefore understood that the active surface of the electromagnet 5 in question is facing the rotor 3.

[0048] Preferably, each of said electromagnets 5 has a flange abutting against one or more walls of the stator 2 forming the associated opening. The electromagnets 3 are held in position in the associated opening, for example by means of one or more screws passing through the flanges to be housed in the parts of the stator 2 in contact with the flanges.

[0049] The electromagnets 5 are furthermore arranged so as to be distributed, preferably at regular intervals, over 360 degrees in the stator 2.

[0050] The electromagnets 5 are preferably a multiple of three in number. The electromagnets 5 are thus at least three. In the example illustrated, the electromagnets 5 are twelve in number.

[0051] According to one option, the plurality of electromagnets 5 is powered by a three-phase alternating current power supply. Such a power supply thus provides a three-phase current. The three-phase current is composed of three different phases. These three phases are alternating signals which are of the same intensity and the same frequency, the signals being moreover phase-shifted from each other by one-third of a period.

[0052] Each of the electromagnets 5 is thus powered either by the first phase, or by the second phase or by the third phase. More precisely, the electromagnets 5 are distributed into three groups of equal number of electromagnets 5 so that all the electromagnets 5 of the first group are powered by the first phase, all the electromagnets 5 of the second group are powered by the second phase and all the electromagnets 5 of the third group are powered by the third phase.

[0053] In the present case, the electromagnets 5 of the three groups are configured so as to generate a rotating magnetic field when they are powered. For this purpose, the electromagnets 5 of each of the three groups are regularly distributed around the stator 2. Typically, an electromagnet 5 of the first group is followed by an electromagnet 5 of the second group, which is itself followed by an electromagnet 5 of the third group, and so on.

[0054] Preferably, each electromagnet 5 of a given group is radially aligned with another electromagnet 5 of the same group.

[0055] In this way, by means of the different phases, each of the groups of electromagnets 5 creates a magnetic field in turn, which thus generates a magnetic field rotating around an axis of rotation which is coaxial with the X axis.

[0056] The rotating magnetic field generates eddy currents in the rotor 3 when the rotor 3 pivots opposite the electromagnets. The magnetic flux defined by the magnetic field of the electromagnets 5 is here an axial magnetic flux (because the main faces 2a and 2b of the stator 2 and the rotor 3 are parallel to each other and the electromagnets 5 are carried so as to extend from the main face 2a of the stator 2).

[0057] If we return to the general configuration of the braking device, the electromagnets 5 of the first stator 2 and of the second stator 2 are preferably arranged symmetrically relative to a central plane of symmetry passing through the rotor 3. Thus each electromagnet 5 of the first stator 2 is arranged opposite an electromagnet 5 of the second stator 2 and vice versa. Preferably, each electromagnet 5 of the first stator 2 is axially aligned (along an axis parallel to the X axis) with an electromagnet 5 of the second stator 2.

[0058] Preferably, also each electromagnet 5 of the first stator 2 and of the first group is arranged (and preferably axially aligned along an axis parallel to the axis X) opposite an electromagnet 5 of the first group of the second stator 2 and vice versa. Preferably, also each electromagnet 5 of the first stator 2 and of the second group is arranged (and preferably axially aligned along an axis parallel to the axis X) opposite an electromagnet 5 of the second group of the second stator 2 and vice versa. Preferably, also each electromagnet 5 of the first stator 2 and of the third group is arranged (and preferably axially aligned along an axis parallel to the axis X) opposite an electromagnet 5 of the third group of the second stator 2 and vice versa.

[0059] Also preferably, for at least one pair of aligned electromagnets (and preferably for all pairs), electromagnet 5 of the first stator 2 / electromagnet 5 of the second stator 2, said electromagnets are magnetically oriented in the same way along their alignment axis. Thus, if the north pole of the electromagnet 5 of the first stator 2 is opposite the rotor 3 then it is the south pole of the electromagnet of the second stator 2 which is opposite the rotor 3, and vice versa.

[0060] In this way, the rotor 3 is thus framed on each of its main faces 3a, 3b by the active surfaces of the different electromagnets 5.

[0061] It is also recalled that the plurality of electromagnets 5 of the first stator 2 is powered by a three-phase alternating current power supply which has been described previously. The three-phase alternating current supply of the plurality of electromagnets 5 of the second stator 2 may be the same supply as that of the plurality of electromagnets 5 of the second stator 2 (the two stators 2 then being able to be connected in series or in parallel) or else be another three-phase alternating current supply (the two stators 2 then being connected independently of each other).

[0062] Here the three-phase alternating current power supply of the plurality of electromagnets 5 of the second stator 2 is the same as that of the plurality of electromagnets 5 of the second stator 2.

[0063] The electromagnets 5 of the first stator 2 and the electromagnets 5 of the second stator 2 thus arranged together define a general magnetic field in the direction of the rotor 3 when they are powered. Indeed, the electromagnets 5 of the two stators 2 will interact with each other since magnetic loops will be created between the electromagnets 5 facing each other between the two stators 2 thus passing through the rotor 3 in passing.

[0064] This configuration thus makes the magnetic field more intense in the rotor 3. In this way, the braking torque exerted by the stators 2 on the rotor 3 is intensified, which makes it possible to brake the rotor 3 very well.

[0065] It is understood that the electromagnets 5 of the two stators 2 are arranged so that the different electromagnets 5 associated with the same phase will be powered at the same time and in the same direction, thus forming a local magnetic field. The successive power supply of the different groups of electromagnets 5 will thus make it possible to generate a general rotating magnetic field, which is the sum of the different local magnetic fields.

[0066] The electromagnets 5 are preferably mounted in stars on each of the stators 2. Other assemblies are also possible, such as, for example, a triangle assembly.

[0067] We will now examine in more detail the braking control by the magnetic braking device 1 with reference to [Fig.4].

[0068] The magnetic braking device 1 has an electronic control unit 7 capable of controlling the alternating electrical power supplied to the various electromagnets 5.

[0069] In particular, the control unit 7 controls the electromagnets 5, and in particular their electrical power supply, so that the speed of rotation of the general magnetic field is adapted as a function of at least one data characteristic of the speed of rotation of the rotor 3.

[0070] For this purpose, the magnetic braking device 1 comprises or is connected to at least one sensor 8 for measuring a data characteristic of the rotation speed. of the rotor 3. For example, the measuring sensor 8 is a sensor for measuring the rotation speed of the wheel 103 or directly a sensor for measuring the rotation speed of the rotor 3 or even a sensor for measuring the ground speed of the aircraft 100.

[0071] The control unit 7 thus receives as input one or more pieces of information transmitted by the sensor 8, information representative of the rotation speed of the rotor 3. The control unit 7 can directly receive the information from the sensor 8 or can receive the information from another control unit which will determine from the data supplied by the sensor 8 a piece of data on the rotation speed of the rotor 3, data which will then be transmitted to the control unit 7.

[0072] The control unit 7 also receives as input one or more pieces of information representative of braking to be applied by the magnetic braking device.

[0073] For example, the information is a braking command such as a braking torque command to be generated by the magnetic braking device 1. For example, the braking command is a ratio of the targeted braking torque to the maximum braking torque Cmax that can be generated by the magnetic braking device 1. For example, this ratio is determined from the position of the brake pedal. This command can be generated directly from the pilot's control unit and transmitted to the control unit 7 and / or calculated by another control unit (such as an autopilot control unit) than the control unit 7 and transmitted to the control unit 7.

[0074] Alternatively, the control unit 7 itself determines such a braking order from the information(s) transmitted by the pilot's control unit and / or another control unit (such as an autopilot control unit). For example, the control unit 7 receives as information from the pilot a target braking torque and deduces therefrom the ratio of target braking torque to maximum braking torque Cmax that can be generated by the magnetic braking device 1.

[0075] From there, the control unit 7 controls the electrical supply of the electromagnets 5 to adapt the braking torque applied to the wheel 103 via the rotor 3.

[0076] It is therefore understood that the control unit 7 thus manages the braking device to adapt in real time the resistive torque applied to the wheel 103.

[0077] Preferably, the control unit 7 acts on one or more phases of the alternating electrical supply of the electromagnets 5 in order to modify the speed of rotation of the general magnetic field generated by the electromagnets 5 of the two stators 2.

[0078] Preferably, the control unit 7 acts on one or more characteristics of at least one of the phases of the alternating electrical supply of the electromagnets 5. For example, the control unit 7 acts on the oscillation frequency of the phase and / or on the amplitude of the phase and / or on the intensity of the phase and / or on the direction of the phase and / or the order of activation of the different phases.

[0079] By modifying one or more characteristics of one, several or all of the phases of the alternating electrical power supply of the electromagnets 5, the control unit 7 can thus control the speed of rotation of the general magnetic field generated between the two stators 2.

[0080] Thus, the rotational speed of the magnetic field can be controlled so that the differential in rotational speeds between that of the rotating magnetic field and that of the rotor 3 makes it possible to achieve the targeted braking torque.

[0081] The control of the electromagnets 5 proves to be easy and efficient thanks to the power supply and the three-phase connection.

[0082] Preferably, in order to optimize the braking applied by the magnetic braking device 1 to the wheel 103, the control unit 7 is configured to adapt the rotation speed of the general magnetic field also as a function of the maximum braking torque Cmax that can be generated by the magnetic braking device 1.

[0083] Indeed, according to the state of the art, as illustrated in [Fig. 5], the braking torque that can be generated by an eddy current braking device of the prior art depends on the rotational speed of the rotor of said device. The braking torque increases with the rotational speed of the rotor up to a given rotor rotational speed (dependent on the dimensions and configuration of the braking device in question). From this speed, the braking torque decreases even as the rotational speed of the rotor increases.

[0084] The technical solution of the invention makes it possible to avoid this drawback.

[0085] Indeed, the control unit 7 is configured to adapt the rotation speed of the general magnetic field so that the magnetic braking device 1 is able to deliver the desired braking torque regardless of the rotation speed of the rotor 3. Thus, if the desired braking torque is, for example, the maximum braking torque Cmax that can be delivered by the magnetic braking device 1 (corresponding to the peak of the curve visible in [Fig. 5]), the control unit 7 manages the rotation speed of the rotating general magnetic field so that the differential in rotation speeds between the rotating magnetic field and the rotor 3 corresponds to this value of the maximum braking torque Cmax.

[0086] In this way, the fact that the braking performance of the magnetic braking device 1 is no longer (or significantly less) dependent on the rotational speed of the rotor 3 is further amplified.

[0087] For example, if the desired braking torque is the maximum braking torque Cmax , when the rotor 3 rotates at a rotation speed co which is lower than the speed of maximum cocoupie rotation corresponding to the maximum braking torque Cmax, the rotation speed differential must be increased. The control unit 7 then controls the alternating electrical power supply so as to generate a magnetic field rotating in a direction opposite to that of the rotor 3 and of a value such that it makes it possible to reach or greatly approach Cmax.

[0088] For example, if the desired braking torque is the maximum braking torque Cmax, when the rotor 3 rotates at a rotation speed co which is greater than the rotation speed cocoupie max corresponding to the maximum braking torque Cmax, the rotation speed differential must be reduced. The control unit 7 then controls the alternating electrical power supply so as to generate a magnetic field rotating in the same direction as that of the rotor 3 and of a value such that it makes it possible to reach or greatly approach Cmax.

[0089] Thus for these two cases, the control unit 7 manages the alternating electrical power supply of the electromagnets 5 so that the rotation speed of the magnetic field is equal to the rotation speed of the rotor minus the critical speed (here ^max torque) • - If the rotation speed of rotor 3 is greater than max cocoup, then the rotation speed of the magnetic field is positive and the rotation speed differential must be adjusted in order to reach max cocoup, - If the rotor rotation speed is lower than max.coupie, then the magnetic field rotation speed is negative and the rotation speed differential must be adjusted to reach max.coupie.

[0090] The magnetic braking device 1 thus described makes it possible to generate magnetic braking of the wheel 103 with an intensity of said braking controlled (by adapting the differential in rotation speeds).

[0091] The magnetic braking device 1 thus described makes it possible to optimize the braking applied to the wheel 103 thanks to real-time control of the relative speed differential between the rotation speed of the rotor 3 and the rotation speed of the general rotating magnetic field.

[0092] In particular, the braking performance of the magnetic braking device 1 is no longer (or significantly less) dependent on the rotational speed of the rotor 3.

[0093] In practice, under the control of the control unit 7, the magnetic braking device delivers the desired braking torque, between 0 and Cmax (terminals included), whatever the rotation speed of the rotor 3.

[0094] Furthermore, the control unit 7 can here simply act on one or more oscillation frequencies of one or more phases associated with different groups of electromagnets 5 without necessarily changing their amplitude. This makes it possible to have a relatively simple to operate and relatively energy-efficient control unit 7.

[0095] Advantageously, unlike magnetic devices of the prior art, the stators 2 are fixed in translation relative to the shaft 102 carrying them. The air gap between the stators 2 and the rotor 3 is therefore constant. In this way, the actuators of the prior art necessary to move the stator relative to the rotor are dispensed with, which limits the mass and size of the present magnetic braking device 1.

[0096] Preferably, the magnetic braking device 1 is configured to be able to be used also in a motor mode. In this motor mode (as opposed to that in which it provides a braking torque to the wheel 103), the magnetic braking device 1 provides a motor torque to the wheel 103.

[0097] Preferably, the wheel 103 is also equipped with an additional braking device 9 and for example a braking device of the prior art such as for example a friction braking device.

[0098] For example, the additional braking device 9 extends in front of the entrance to the annular space. The additional braking device 9 here extends partly outside the annular space and partly inside the annular space. The magnetic braking device 1 extends further inside the annular space than the additional braking device 9.

[0099] The additional braking device 9 comprises friction members, for example a stack of carbon discs and a plurality of actuators carried by an actuator holder. The actuators can be of the mechanical, hydraulic or electrical type.

[0100] For example, each actuator is an electromechanical actuator which comprises an electric motor and a pusher capable of being moved by the electric motor to press the stack of discs. The electromechanical actuator is thus intended to produce a controlled braking force on the stack of discs.

[0101] The (optional) addition of an additional braking device 9 is particularly advantageous when it is necessary to keep the aircraft 100 stationary for a long period, for example during the aircraft parking phases. Indeed, the additional braking device 9 can then be used without energy input.

[0102] The addition (optional) of an additional braking device 9 is also advantageous for assisting and / or replacing the magnetic braking device 1 in situations in which the magnetic braking device 1 will have difficulty in being able to brake the wheel alone (which can happen in certain areas of rotation speed of the wheel or electrical power supply of the electromagnets 5).

[0103] Of course, the invention is not limited to the embodiment described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0104] The invention can be used on any type of vehicle, for example a land vehicle or an aerial or amphibious vehicle.

[0105] The magnetic braking device may have a structure different from that described.

[0106] For example, the stator and / or the rotor may be shaped so that eddy currents are generated only in one angular segment of the stator (respectively the rotor) and not over the entire circumference of the stator (respectively the rotor). For this purpose, the electromagnets could be arranged only on one angular segment of the stator and / or the rotor.

[0107] The electromagnets may be carried by the rotor instead of the stator. The conductive material may be carried by the stator instead of the rotor.

[0108] The electromagnets may also be distributed between the stator and the rotor. For example, the stator and the rotor could both be made of electrically conductive material and the electromagnets distributed between the stator and the rotor. The electromagnets would then be preferentially arranged over a larger angular segment on one of the stator or the rotor than on the other of the stator or the rotor.

[0109] The electromagnets and the facing magnetic material may be arranged to produce between a stator and a rotor a solely radial flux or an axial flux or a solely axial flux.

[0110] The number of electromagnets may be different from what has been indicated.

[0111] The number of stators may be different from what has been indicated. In particular, A single stator may be associated with each rotor (or with the rotor alone). The stator will then be arranged, for example, on one side of the rotor. Preferably, a metal part will then be provided to close the magnetic field loops to improve the performance of the braking device. The metal part will then be arranged on the other side of the rotor. The metal part will be, for example, a yoke, a disc, a plate, a rolled sheet, etc. The metal part could, for example, be made of steel, for example, magnetic steel.

[0112] The control unit may be different from what has been indicated. For example, the control unit may be configured to adapt the braking torque provided by the magnetic device according to a parameter linked to the sliding of the wheel on the ground. Indeed, it is possible with the device described to control the braking torque provided by the magnetic braking device. The control unit will thus be able to prevent the braking device from providing a braking torque for which slipping of the wheel is possible.

[0113] The additional braking device may be different from what has been described. For example, the number of discs, the type of discs and the positioning of the discs may be different. For example, the additional braking device may be different from a rotor / stator friction disc braking device. For example, the additional braking device may be a caliper type.

[0114] The arrangements of the additional braking device and / or the magnetic braking device may be reversed. For example, the magnetic braking device may be arranged outside the annular space and the additional braking device may be arranged in the annular space.

[0115] The additional braking device and the magnetic braking device may be attached to the shaft by the same torsion tube or by at least one different tube each.

[0116] Although here the magnetic braking device is arranged on the inside of the wheel (i.e. the side of the wheel closest to the leg carrying it), the magnetic braking device may be arranged on the outside of the wheel (i.e. the side of the wheel furthest from the leg carrying it). For two wheels carried by the same shaft and both equipped with such a magnetic braking device, one of the devices may be arranged on the inside of one of the wheels and the other on the outside of the other of the wheels.

[0117] The electrical power supply of the electromagnets may be different from what has been indicated and may be, for example, multi-phase (with a number of phases N greater than or equal to 2 and, for example, greater than or equal to 3 and, for example, greater than or equal to 4) or even single-phase with an adapted configuration of the electromagnets.

[0118] It is indeed possible to generate a rotating magnetic field by means of only two groups of electromagnets, each of the groups being associated with a power supply phase. In this case the power supply can be two-phase or even single-phase. In the latter case, it is possible to provide a first group of at least two electromagnets forming two parallel primary windings and a second group of at least two electromagnets forming two parallel secondary windings and arranged orthogonal to the two primary windings, a capacitor being connected in series with the secondary windings. In this way, the phase of the secondary windings will naturally be offset by 90 degrees relative to that of the primary windings, allowing the generation of a rotating magnetic field between the electromagnets despite the single-phase power supply.

[0119] The electromagnets can thus be grouped into N groups. N is for example a multiple of 2 or 3.

[0120] Preferably, the braking device will comprise at least two groups of electromagnets, each group comprising at least one electromagnet and all groups comprising the same number of electromagnets. For example, the device braking system will have as many groups of electromagnets as there are phases in the alternating current supply supplying said groups of electromagnets.

[0121] Within the same group of electromagnets, the electromagnets may be powered in series, in parallel or independently of each other (while being powered by the same phase).

Claims

Claims

1. Magnetic braking device comprising at least one stator (2) and at least one rotor (3), and electromagnets (5) secured to the rotor and / or the stator to produce between them, when the rotor rotates, at least one magnetic field capable of generating eddy currents braking the rotor, the device being characterized in that it comprises at least one control unit (7) capable of controlling an alternating electrical power supply of at least a portion of the electromagnets so that the magnetic field is a rotating magnetic field, the control unit being configured to adapt a rotation speed of said magnetic field as a function of at least one data characteristic of the rotation speed of the rotor by acting on at least one of the parameters of the electrical power supply of at least one of the electromagnets.

2. Braking device according to claim 1, in which the electromagnets (5) are all integral with the stator (2).

3. Braking device according to one of the preceding claims, wherein the electromagnets (3) are arranged at regular intervals on the stator (2).

4. Braking device according to one of the preceding claims, in which the stator (2) has openings each receiving one of the electromagnets, each of said electromagnets having a flange abutting against one or more walls of the stator (2) forming the associated opening.

5. Braking device according to one of the preceding claims, in which the electromagnets are distributed into N groups, each group comprising at least one electromagnet and each of the N groups comprising the same number of electromagnets, the alternating current supply being an alternating current supply comprising N phases, each group of electromagnets being associated with a respective one of said phases.

6. Braking device according to one of the preceding claims, in which the parameter on which the control unit (7) acts is a phase of the alternating electrical supply associated with at least one electromagnet (5).

7. Braking device, according to one of the preceding claims, in which the control unit (7) is configured to adapt a rotational speed of said magnetic field also as a function of a desired braking torque, in a braking torque range from zero to a maximum braking torque that can be generated by the braking device.

8. Braking device according to one of the preceding claims, wherein the braking device can be used in a motor mode providing motor torque to the rotor (3).

9. Braked wheel, comprising the braking device according to one of the preceding claims.

10. An aircraft, comprising a braked wheel according to claim 9.

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