Wheel with magnetic braking device; aircraft landing gear and aircraft equipped with such a wheel

Abstract

A wheel comprising a magnetic eddy current braking device, the device comprising at least one stator and at least one rotor, and magnets attached to one of these to produce a magnetic flux between them capable of generating eddy currents in the other when the wheel rotates. According to the invention, the rotor is rotationally linked to the wheel by means of a wheel transmission mechanism. Lander and aircraft comprising such a wheel. FIGURE IN ABRIDGED DIAGRAM: Fig. 8

Description

Title of the invention: Wheel with magnetic braking device; aircraft landing gear and aircraft equipped with such a wheel

[0001] The present invention relates to the field of braking of vehicle wheels such as aircraft wheels.

[0002] The present invention relates to a wheel carrying a magnetic braking device as well as an aircraft landing gear and an aircraft equipped with such a wheel.

[0003] BACKGROUND OF THE INVENTION

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

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

[0006] Also known are magnetic braking devices with eddy current (called "Eddy current" in English) used for braking vehicle wheels and more particularly aircraft wheels.

[0007] Document FR-A-3122405 describes such a device comprising a rotor linked in wheel rotation, two stators that frame the rotor and are rotationally linked to the wheel support shaft and free in translation relative to said shaft, magnets to produce an axial magnetic flux between the stators and the rotor, and linear actuators to axially move the stators between a maximum braking position in which the stators are close to the rotor and a free wheel rotation position in which the stators are away from the rotor.

[0008] However, even in the maximum braking position, the performance of the eddy current magnetic braking device depends on the rotor speed relative to the stator and reaches a peak at a predetermined speed, depending on the device's design and, in particular, the materials used. Generally, the performance of the eddy current magnetic braking device is not satisfactory when the aircraft carrying said device is traveling at low speed.

[0009] Moreover, more generally, the performance of an eddy current magnetic braking device depends on the power and dimensions of the magnets used. However, mass and size are significant constraints and therefore incompatible with aeronautical applications.

[0010] SUBJECT OF THE INVENTION

[0011] The invention aims in particular to provide a braked wheel remedying at least partly due to the aforementioned disadvantages. Summary of the invention

[0012] For this purpose, a wheel is provided, intended to be supported by a shaft, the wheel comprising a magnetic eddy current braking device, the device comprising at least one stator and at least one rotor, and magnets attached to one of these to produce between them a magnetic flux capable of generating eddy currents in the other of these when the wheel rotates.

[0013] According to the invention, the rotor is linked in rotation to the wheel by means of a motion transmission mechanism.

[0014] Thus, for a given wheel rotation speed, the transmission mechanism, via an adapted transmission ratio, allows the rotor to rotate within a speed range that permits improved braking device performance. The presence of the transmission mechanism and the ability to select its transmission ratio give the braking device designer greater freedom in the arrangement of the braking device, the materials chosen, the power of the selected magnets, the electromagnet supply currents, etc.

[0015] According to a first embodiment, said mechanism is arranged so that the rotor has a rotational speed greater than a rotational speed of the wheel.

[0016] The transmission mechanism is then a multiplier having a transmission ratio greater than 1.

[0017] For example, thanks to the transmission mechanism, the rotor remains at a rotational speed higher than that of the wheel.

[0018] This allows, for example, the magnetic braking device to be used at a lower wheel rotation speed than with prior art devices.

[0019] The transmission mechanism has, for example, a multiplying effect for the transmission of the braking torque from the rotor to the wheel.

[0020] According to a second embodiment, said mechanism is arranged so that the rotor has a rotational speed lower than a rotational speed of the wheel.

[0021] The transmission mechanism is then a reducer with a transmission ratio less than 1.

[0022] For example, in the case where the rotational speed of the wheel during an aircraft landing is greater than the maximum performance speed of the braking device, the use of a transmission mechanism reducing the speed of the rotor relative to the speed of the wheel allows the braking device to be more effective from the start of braking.

[0023] For example, in the case where the rotor carries the magnets of the magnetic braking device, the centrifugal force causes significant mechanical stresses on the magnets' attachment to the rotor. Reducing the rotor's rotational speed allows for less stress on the magnets' attachments from the centrifugal force.

[0024] The magnetic braking device thus proves to be more efficient while maintaining a standard size and mass for this type of device, and without being more complex.

[0025] Optionally, the transmission mechanism includes an internally toothed ring arranged to be fixed coaxially to the rotor, a planet carrier arranged to be fixed coaxially to the rim and which carries planets that mesh with the internally toothed ring, and a central externally toothed planet gear that meshes with the planets and carries the rotor.

[0026] Optionally, the transmission mechanism includes an internally toothed ring arranged to be fixed to the rim coaxially therewith, a planet carrier which is intended to be fixed to the shaft, the planet carrier carrying planets meshing with the internally toothed ring, and a central externally toothed planet gear meshing with the planets and carrying the rotor.

[0027] Optionally the transmission mechanism includes an internally toothed ring, a planet carrier which is intended to be integral with the shaft, the planet carrier carrying planets that mesh with the internally toothed ring, the rotor being carried by one of the planets.

[0028] Optionally, the magnetic braking device comprises several rotors, each carried by one of the satellites.

[0029] Optionally, the device comprises as many stators as rotors, each stator being mounted at the level of one of the rotors coaxially with it.

[0030] Optionally, the internally toothed crown is arranged to be fixed coaxially to the rim.

[0031] Optionally at least one rotor rotates around an axis of rotation which is parallel and offset from an axis of rotation of the wheel.

[0032] Optionally, the at least one rotor comprises at least one face extending opposite a face of the stator, the face in which eddy currents are generated being smaller in size than the opposite face.

[0033] Optionally, the rotor and stator are configured so that currents of eddy currents are generated only in one angular segment of the stator or rotor.

[0034] Optionally, one of the rotor and stator is a disk and the other of the rotor and stator is a ring divided into at least two ring sectors movable radially between a first position in which each ring sector has at least one face opposite a face of the disk to establish the axial magnetic flux and a second position in which said at least one face of the ring sector is offset radially with respect to the face of the disk to interrupt the axial magnetic flux, the device comprising at least one actuator connected to the ring sectors to move the ring sectors between their two positions.

[0035] Optionally, the wheel comprises a rim and a hub connected by a disc defining an annular space, the braking device being placed in front of an entrance of the annular space, the crown being intended to be fixed to the shaft.

[0036] Optionally, the rotor and stator are arranged so that the magnetic flux capable of generating eddy currents is an axial flux.

[0037] The invention also relates to a landing gear comprising a leg having an end carrying the shaft on which is mounted the hub of a wheel such as the one mentioned above.

[0038] The invention relates to an aircraft comprising at least one landing gear as described above.

[0039] Other features and advantages of the invention will become apparent from the following description of particular, non-limiting embodiments of the invention. Brief description of the drawings

[0040] Reference will be made to the attached drawings, among which:

[0041] [Fig. 1] [Fig. 1] is a partial schematic front view of an aircraft equipped of landing gear according to the invention;

[0042] [Fig.2] [Fig.2] is a partial schematic view of a wheel according to a first mode of realization of the invention, in axial half-section;

[0043] [Fig.3] [Fig.3] is a front view of part of a transmission mechanism the wheel illustrated in [Fig.2];

[0044] [Fig.4] [Fig.4] is a front view of another part of the mechanism wheel transmission illustrated in [Fig.2];

[0045] [Fig. 5] [Fig. 5] is a partial schematic view of a wheel according to a second embodiment of the invention, in axial half-section, the crown sectors being in their second position or free rotation position of the wheel;

[0046] [Fig.6] [Fig.6] is a schematic perspective view of the wheel shown in the [Fig.5], the crown sectors being in their second position;

[0047] [Fig.7] [Fig.7] is a schematic perspective view of the wheel shown in the [Fig.5], the crown sectors being in their first position or maximum braking position;

[0048] [Fig-8] [Fig.8] is a schematic perspective view of a wheel according to a third embodiment of the invention, ;

[0049] [Fig.9] [Fig.9] is a partial schematic view of the wheel illustrated in [Fig.8], in axial half-section;

[0050] [Fig. 10] [Fig. 10] is a schematic perspective view of a wheel according to a fourth embodiment of the invention;

[0051] [Fig. 11] [Fig. 11] is a partial schematic view of the wheel according to a fifth embodiment of the invention, in axial half-section;

[0052] [Fig. 12] [Fig. 12] is a partial schematic view of the wheel according to a sixth embodiment of the invention, in axial half-section. DETAILED DESCRIPTION OF THE INVENTION

[0053] Fig. 1 represents an aircraft 100 comprising landers 101.

[0054] At least one of the landers 101 comprises a leg having an end equipped here of two coaxial shafts 102 on each of which is mounted to pivot at least one wheel 103, each shaft 102 having a central axis defining an X axis of rotation of the wheel 103 which it carries.

[0055] At least one of the wheels 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 disc 106. The rim 105 and the hub 104 define between them an annular space 107 having one end closed by the disc 106 and one end open towards the outside of the wheel 103 forming an entrance to the annular space 107. The rim 105 is encircled by a tire (not shown) received between two lips 108 of the rim 105.

[0056] According to the invention, at least one of the wheels is equipped with a magnetic braking device generally designated in 1.

[0057] The magnetic braking device 1 extends for example in front of the entrance of the annular space 107, outside of it.

[0058] With reference to figures 2 to 4, a first embodiment will now be described.

[0059] The magnetic braking device 1 comprises a fixed element, or stator 2, and a moving element, or rotor 3.

[0060] The stator 2 is the part of the device rotationally linked to the shaft 102 or to the lander leg 101, here via a torsion tube 5.

[0061] The torsion tube 5 comprises a body 5.1 engaged on an external flange 102' of the shaft 102, and an internal flange 5.2 which is fixed (for example by screws) to the flange 102'.

[0062] Preferably, the stator 2 is mounted on the torsion tube 5 so as to also be able to slide axially (i.e. parallel to the X-axis) along said tube. torsion 5 and therefore along the shaft 102 or the lander leg 101.

[0063] The magnetic braking device 1 then comprises at least one actuator 6 connected to the stator. For example, the actuator 6 is rotationally linked to the shaft 102 or to the leg of the lander 101.

[0064] The actuator is optionally connected to the stator 2 via a plate 7. More specifically here, the body of each actuator 6 receives a sliding piston which is movable in translation along an axial direction and which has a free end section on which the plate 7 is fixed: thus, via the plate 7, the stator 2 can slide relative to the shaft 102 (or the leg of the lander) and thus move closer to or further away from the wheel 103.

[0065] Therefore, the stator 2 is movable between a maximum braking position in which the stator 2 is close to the rotor 3 and a free rotation position of the wheel 103 in which the stator 2 is away from the rotor 3.

[0066] Moreover, the stator 2 preferably has a crown shape coaxial with the wheel 103 and the shaft 102.

[0067] The stator 2 comprises, for example, a non-magnetic support provided with a plurality of magnets 4 having free faces (opposite to those carried by the support). The magnets 4 are, for example, permanent magnets.

[0068] The magnets 4 generate magnetic fields to produce a magnetic flux in the direction of the rotor 3 located opposite, i.e. an axial magnetic flux parallel to the X axis.

[0069] 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....

[0070] In the present case, the rotor 3 has an annular disc shape coaxial with the wheel 103 and the shaft 102.

[0071] The magnetic braking device includes a motion transmission mechanism 10 through which the rotor 3 is rotationally linked to the wheel 103. The transmission mechanism 10 is here a multiplier such that the rotor 3 has, in operation, a rotational speed greater than a rotational speed of the wheel 103.

[0072] The transmission mechanism 10 is here of the epicycloidal type.

[0073] The transmission mechanism 10 thus comprises an internally toothed crown 11 (visible in [Fig. 3]) arranged to be fixed coaxially to the rotor 3. The internally toothed ring 11 thus carries the rotor 3 so that it is coaxially aligned with the stator 2.

[0074] The transmission mechanism 10 also includes a planet carrier 12 and planets 13, carried by the planet carrier 12 and meshing with the internally toothed ring 11. The planet carrier 12 is fixed to the rim 105 coaxially with it.

[0075] The transmission mechanism 10 also includes a central planetary gear 14 to external teeth, illustrated in [Fig.4], meshing with the satellites 13.

[0076] The central planetary gear 14 is here part of the torsion tube 5. The central planetary gear 14 thus forms internally at least a part of the body 5.1.

[0077] The central planetary gear 14 is thus rotationally fixed to the shaft 102 and coaxial with said shaft 102.

[0078] Furthermore, the central planetary 14 has externally a first section 14.1 provided with external teeth for the generation with the satellites 13.

[0079] The central planetary gear 14 externally comprises, for example, a second section 14.2, successive to the first and coaxial with the first, the second section 14.2 having a larger external diameter than the first section 14.1.

[0080] The rotor 3 is therefore linked in rotation to the wheel 103 via the rim 105 and the transmission mechanism 10.

[0081] The rotor 3 rotates on itself around its central axis relative to the stator 2 which faces it: during this movement of the rotor 3 in a circumferential direction relative to the stator 2, a main face of the rotor 3 remains parallel to a main face of the stator 2 (and therefore to the free faces of the magnets).

[0082] The actuator 6 moves the stator 2 along an axial direction of the wheel 103 between: - a first position, or maximum braking position of the wheel 103, in which the stator 2 is brought closer to the rotor 3, and; - a second position, or free rotation position of the wheel 103, in which the stator 2 is separated from the rotor 3.

[0083] When the stator 2 is in the maximum braking position, the magnetic field of the magnets 4 produces a magnetic flux sufficient to generate eddy currents in the rotor 3 when the rotor 3 pivots in front of the magnets 4.

[0084] Thanks to the transmission mechanism 10, the rotor 3 remains at a higher rotational speed than the wheel 103, which allows the magnetic braking device 1 to be used at a lower rotational speed of the wheel 103 than in the prior art.

[0085] The magnetic braking device 1 thus proves to be more efficient.

[0086] It is understood that in order to induce braking, the actuator 6 is controlled to bring the stator 2 into the first position and that, in order to interrupt braking, the actuator 6 is controlled to bring the stator 2 into the second position, a position in which the magnets 4 do not allow sufficient eddy currents to be generated in the rotor 3 to induce braking of the rotor 3.

[0087] The actuator control circuit 6 conventionally comprises an electronic brake control unit (not shown here) which receives as input a control signal from an instrument operated by the pilot of the aircraft 100 and transmits control signals to an actuator control unit which produces, From the control signal, a power signal is transmitted to actuator 6 to modify the axial distance between stator 2 and rotor 3 according to the braking force required by the pilot. Modifying the air gap between stator 2 and rotor 3 by actuator 6 will increase or decrease the braking torque and therefore the speed of aircraft 100. Modifying the air gap by actuator 6 affects the magnetic flux transmitted to rotor 3 by magnets 4.

[0088] Other variants are conceivable within the framework of the invention.

[0089] With reference to figures 5 to 7, a second embodiment will now be described.

[0090] Unlike the first embodiment, in which the stator 2 and the rotor 3 could be moved closer together or further apart in an axial direction, in the second embodiment, the stator 2 and the rotor 3 can be moved relative to each other in a radial direction.

[0091] For this purpose, the stator 2 is divided into four identical crown sectors 2A, 2B, 2C, 2D, extending at an angle of 90°. Each crown sector 2A, 2B, 2C, 2D has a U-shaped cross-section (along a plane containing the X axis) with two opposing branches. Each branch preferably includes a non-magnetic support provided with a plurality of magnets 4, for example permanent magnets, having free faces (opposite the branch that bears them) and generating magnetic fields to produce a magnetic flux in the direction of the branch opposite, i.e. an axial magnetic flux parallel to the X axis. The two branches of each sector of the crown 2A, 2B, 2C, 2D, thus provided with magnets 4, delimit between them a groove whose sides are formed by faces 2.1, 2.2 formed at least by the free faces of the magnets 4.

[0092] In this second embodiment, the torsion tube 5 comprises a body 5.1 engaged on an external flange 102' of the shaft 102, an internal flange 5.2 which is fixed (for example by screws) to the flange 102', and an external flange 5.3 carrying actuators 6 here hydraulic.

[0093] In this second embodiment, there are eight actuators 6 arranged in pairs at 90° to each other, and each ring sector 2A, 2B, 2C, 2D is connected to the two actuators 6 of one of the pairs. The actuators 6 of each pair are arranged opposite the actuators 6 of the pair of actuators that are at 180° to them. The actuators 6 may have a body fixed to the outer flange 5.3 of the torsion tube 5, but here they have a body 6.1 in one piece with the outer flange 5.3 of the torsion tube 5. The body 6.1 of each actuator 6 receives, by sliding motion, a piston 6.2 which is movable in translation along a radial direction and which has a free end section on which is fixed one of the arms of one of the crown sectors 2A, 2B, 2C, 2D so that each crown sector 2A, 2B, 2C, 2D is carried and guided by the two actuators 6 of the same pair of actuators.

[0094] The rotor 3 always has an annular disc shape coaxial with the wheel 103 and the shaft 102.

[0095] The rotor 3 is always rotationally linked to the rim 105 of the wheel 103 by means of a transmission mechanism 10 arranged so that the rotor 3 has a speed greater than a rotational speed of the wheel 103.

[0096] In this second embodiment, the internally toothed ring 11 is arranged to be fixed coaxially to the rim, the planet carrier s 12 is fixed to the torsion tube 5 and the externally toothed central planetary gear 14 carries the rotor 3 and is fixed to said rotor 3. The central planetary gear 14 is thus mounted to pivot on a bearing surface of the planet carrier 12 and / or the torsion tube 5.

[0097] The rotor 3 is therefore here supported by the central planetary 14 to be coaxial with the shaft 102 and to be surrounded by the crown sectors 2A, 2B, 2C, 2D.

[0098] The rotor 3 has two main faces 3.1, 3.2, opposite each other, between which extends parallel a median plane coinciding with a median plane of the groove extending parallel and midway between the faces 2.1, 2.2. The faces 3.1, 3.2 are parallel to the faces 2.1, 2.2.

[0099] The rotor 3 is therefore linked in rotation to the wheel 103, here to the rim 105 of the wheel 103 by means of the central planetary 14, and rotates on itself around its central axis relative to the crown sectors 2A, 2B, 2C, 2D which surround it: during this movement of the rotor 3 in a circumferential direction relative to the crown sectors 2A, 2B, 2C, 2D, the main faces 3.1, 3.2 remain parallel to the main faces 2.1, 2.2.

[0100] The actuators 6 move the crown sectors 2A, 2B, 2C, 2D in a radial direction of the wheel 103 between: - a first position, or maximum braking position of the wheel 103, in which the crown sectors 2A, 2B, 2C, 2D of the stator 2 are brought close to the rotor 3, the crown sectors 2A, 2B, 2C, 2D overlapping an external periphery of the rotor 3, so that the faces 2.1, 2.2 of the stator 2 extend opposite the faces 3.1, 3.2 of the rotor 3, being separated from them by a first predetermined air gap and; - a second position, or free rotation position of the wheel 103, in which the crown sectors 2A, 2B, 2C, 2D of the stator 2 are moved away from the rotor 3, the crown sectors 2A, 2B, 2C, 2D being clear of the outer periphery of the rotor 3, so that the faces 2.1, 2.2 of the stator 2 are radially offset outwards relative to the faces 3.1, 3.2 of the rotor 3 and are separated from the faces 3.1, 3.2 by a second predetermined upper air gap at the first predetermined air gap.

[0101] When the crown sectors 2A, 2B, 2C, 2D are in the maximum braking position, the rotor 3 has portions arranged between the branches of the crown sectors 2A, 2B, 2C, 2D and has its opposite faces 3.1, 3.2 facing the faces 2.1, 2.2 of the stator 2 respectively.

[0102] When the crown sectors 2A, 2B, 2C, 2D are in the maximum braking position, the magnetic field of the magnets 4 produces a magnetic flux sufficient to generate eddy currents in the rotor 3 when the rotor 3 pivots in front of the magnets 4.

[0103] The rotor 3 has a thickness such that a skin effect (also called the pellicular effect or Kelvin effect) is generated from each face 3.1, 3.2 of the rotor 3 over more than half of the rotor 3's thickness at least over a range of possible relative speeds of the rotor 3 with respect to the crown sectors 2A, 2B, 2C, 2D. The eddy currents generated from the two faces 3.1, 3.2 will then circulate in the central part of the rotor 3, which will increase the braking torque. This results in a "superposition of skin effects" produced from each face 3.1, 3.2 in the central part, the thickness of the rotor 3 being sufficiently small to achieve this superposition while satisfying the thermal and mechanical constraints. In one example, this superposition provides approximately 60% more performance.

[0104] It will be noted that the branch of each angular sector arranged on the side of face 3.2 ensures a thermal shield function preventing the heat generated in the rotor 3 by the eddy currents from being transmitted to the rim 105 and the tire it carries.

[0105] The actuators 6 are controlled in a manner known in itself to move the crown sectors 2A, 2B, 2C, 2D synchronously between their two positions.

[0106] Apart from the elements developed above, everything that has been said for the first embodiment is also applicable to the second embodiment.

[0107] With reference to figures 8 to 9, a third embodiment will now be described.

[0108] Unlike the first embodiment, in which the entire rotor 3 was subjected to the magnetic flux of the stator 2, in the third embodiment, only a part of the rotor 3 is subjected to the magnetic flux of the stator 2.

[0109] In this third embodiment, the magnetic braking device 1 comprises several fixed elements, or stators 2, and several moving elements, or rotors 3.

[0110] The rotors 3 are made of electrically conductive materials. The rotors 3 are, for example, made of metallic material and, for example, of copper, aluminum, silver, in perfect...

[0111] In the present case, the rotors 3 each have an annular disc shape whose axis extends parallel to the wheel 103 and the shaft 102 but not coaxially with them.

[0112] The magnetic braking device 1 again includes a transmission mechanism 10 through which the rotors 3 are rotationally linked to the wheel 103. The transmission mechanism 10 is such that the various rotors 3 have, in operation, a rotational speed greater than a rotational speed of the wheel 103.

[0113] The transmission mechanism 10 is here of the epicycloidal type.

[0114] The transmission mechanism 10 thus includes an internally toothed crown 11 arranged to be fixed to the rim 105 coaxially with it.

[0115] The transmission mechanism 10 also includes a planet carrier 12 and planets 13, carried by the planet carrier 12 and meshing with the internally toothed ring 11. The planet carrier 12 is fixed coaxially to the shaft 102. For example, the planet carrier 12 is attached to the shaft 102 by means of a torsion tube 5. The torsion tube has a body 5.1 engaged on an external flange 102' of the shaft 102, and an internal flange 5.2 which is fixed (for example by screws) to the external flange 102'. The satellite carrier 12 itself is attached to the internal flange 5.2 (on a face of said flange opposite to that attached to the external flange 102' of the shaft 102) for example by means of screws.

[0116] In this third embodiment, each rotor 3 is carried by one of the satellites 13 coaxially to said satellite 13. Preferably, each satellite 13 is equipped with a rotor 3.

[0117] The transmission mechanism 10 also includes a central planetary gear 14 with external teeth meshing with the planetary gears 13. The central planetary gear 14 is mounted to pivot on a bearing surface of the planetary carrier s 12 and / or the torsion tube 5.

[0118] The rotor 3 is therefore linked in rotation to the wheel 103 via the rim 105 and the transmission mechanism 10.

[0119] It is therefore understood that, as with the first two embodiments, the stators 2 are here the part of the device connected in rotation to the shaft 102 or to the leg of the lander 101. In the present case, the stators 2 are connected in rotation to the shaft 102 via the torsion tube 5. The stators 2 are for example mounted on the body 5.1 of the torsion tube 5 and for example fixed to said body 5.1.

[0120] In the present case, the stators 2 each have an angular sector shape whose axis extends parallel to the wheel 103 and the shaft 102 but not coaxially with them.

[0121] Each stator 2 is here configured as an angular sector with an opening angle between 90 and 200 degrees, and for example between 120 and 190 degrees. Each stator 2 is here configured as a half-ring (i.e., an angular sector with an opening angle of 180 degrees).

[0122] More specifically, here, each stator 2 has a cross-section (along a section plane containing the X-axis) with two opposing branches. The two branches are independent of each other but could alternatively be fixed to each other by an additional central branch, the stator 2 then having a U-shaped cross-section as in the second embodiment. Each of the branches is thus shaped into an angular sector as previously indicated.

[0123] Each angular sector can be decomposed into several sub-sectors jointly forming a single branch, the sub-sectors being fixed together or separated from each other. Each sub-sector can thus carry its own magnet 4.

[0124] Optionally, each magnet 4 is itself shaped into an angular sector and for example an angular sector with an opening angle identical to the sub-sector bearing it.

[0125] Each arm preferably comprises a non-magnetic support provided with a plurality of magnets 4, having free faces (opposite to those carried by the associated arm). The magnets 4 are electromagnets.

[0126] When energized, the magnets 4 generate magnetic fields to produce a magnetic flux in the direction of the branch opposite, i.e. an axial magnetic flux parallel to the X axis.

[0127] The two branches of each stator 2, thus provided with magnets 4, delimit between them a groove whose sides are formed by faces 2.1, 2.2 formed at least by the free faces of the magnets 4.

[0128] Advantageously, each rotor 3 is associated with a dedicated stator 2.

[0129] Each rotor 3 thus has two main faces 3.1, 3.2, opposite each other, between which extends parallel a median plane coinciding with a median plane of the groove extending parallel and midway between the faces 2.1, 2.2. The faces 3.1, 3.2 are parallel to the faces 2.1, 2.2. Each rotor 3 is also supported by one of the satellites 13 to be coaxial with the associated stator 2 and to be surrounded by said stator 2.

[0130] As already stated, the rotors 3 are rotationally linked to the wheel 103, here to the rim 105 of the wheel 103 via the satellites 13, and rotate about their central axis relative to the associated stator 2 that surrounds it. During this circumferential movement of the rotor 3 with respect to the arms of the stator 2 that surround it, the main faces 3.1, 3.2 remain parallel to the main faces 2.1, 2.2.

[0131] The various rotors 3 are thus extended so that their principal faces 3.1 (respectively 3.2) are all arranged in the same first plane (respectively the same second plane, different from the first plane and parallel to it). Furthermore, the various stators are extended so that their principal faces 2.1 (respectively 2.2) are all arranged in the same third plane, different from the first plane and parallel to it (respectively the same fourth plane, different from the first plane and parallel to it).

[0132] The magnetic braking device 1 includes or carries a power supply element (not shown here) for the electromagnets forming here the magnets 4.

[0133] The power supply unit can modulate the electrical supply to the electromagnets between: - a maximum power supply value, corresponding to maximum braking of wheel 103, and; - a zero supply value, corresponding to a free rotation of wheel 103.

[0134] When the electromagnets are powered, the magnetic field of the magnets 4 of each stator 2 produces a magnetic flux sufficient to generate eddy currents in the associated rotor 3 when the rotor 3 pivots in front of the magnets 4.

[0135] Advantageously, these eddy currents are generated only in a single angular segment of the rotors 3, namely the angular segments of the rotors 3 located at the level of the branches of the associated stator 2. Indeed, because the stator 2 (and therefore its branches) does not form a complete disk, the associated rotor 3 is only partially enclosed by the associated stator 2. The remainder of the rotor 3 (i.e., the angular segment of the rotor 3 complementary to that arranged in the groove of the associated stator 2) then acts as a heat sink. In fact, the eddy currents cause the rotor 3 to heat up: the complementary angular segment in contact with the surrounding air can then dissipate this heat. Advantageously, this dissipation occurs by forced convection due to the rotation of the rotor.

[0136] Because each rotor 3 rotates, it is understood that the same portion of the rotor 3 will belong successively and periodically either to the angular segment in which the eddy currents are generated or to the complementary angular segment.

[0137] Even more advantageously, the rotors 3 rotate at a higher rotational speed than the wheel 103, which further promotes this forced convection.

[0138] This limits the risk that the heat generated in the rotors 3 by the eddy currents is transmitted to the rim 105 and the tire it carries.

[0139] Furthermore, it is noted that the branch of each stator 2 arranged on the side of the face 3.2 of the associated rotor provides a thermal shielding function, said branch being in fact arranged between the rotor 3 and the rest of the magnetic braking device 1.

[0140] This further limits the risk that the heat generated in the rotor 3 by the eddy currents may be transmitted to the rim 105 and the tire it carries.

[0141] It is also noted that the rotors 3 are arranged so that their axes of rotation respective are parallel to the axis of rotation X of the wheel 103 to be braked but radially offset from said axis of rotation X.

[0142] It is further noted that the rotational speed of the rotors 3 is proportional to that of the wheel 103 to be braked.

[0143] Preferably, each rotor 3 has a thickness such that a skin effect (also called a film effect or Kelvin effect) is generated from each face 3.1, 3.2 of the rotor 3 over more than half the thickness of the rotor 3 (for the angular segment present in the groove) at least over a range of possible relative speeds of the rotor 3 with respect to the associated stator. The eddy currents generated from the two faces 3.1, 3.2 (for the angular segment present in the groove) will then circulate in the central part of the rotor 3, which will increase the braking torque. A "superposition of skin effects" produced from each face 3.1, 3.2 is thus obtained in the central part, the thickness of the rotor 3 being sufficiently small to achieve this superposition while satisfying the thermal and mechanical constraints. In one example, this superposition provides approximately 60% more performance.

[0144] Apart from the elements developed above, everything that has been said for the first embodiment or the second embodiment is also applicable to the third embodiment.

[0145] Of course, the invention is not limited to the embodiments described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0146] The invention is usable on any type of vehicle and for example a land vehicle or even an aerial or amphibious vehicle.

[0147] The invention is usable for applications other than a vehicle and for example for any industrial or personal equipment requiring braking.

[0148] The magnetic braking device may have a different structure from that described.

[0149] The different embodiments described can thus be combined with each other.

[0150] For example, in the third embodiment, an associated stator may be present with several rotors, or even with all rotors, as in the first embodiment or the second embodiment.

[0151] For example, the stator and / or rotor of the first embodiment or of the second embodiment may be shaped so that eddy currents are generated only in an angular segment of the stator (respectively the rotor), as in the third embodiment, and not over the entire circumference of the stator (respectively the rotor).

[0152] For example, the stators of the third embodiment may be mounted on the torsion tube so that they can be moved closer to or further from the rotors to modulate the braking force as in the first or second embodiment. For example, at least one of the arms of each stator can be slidably mounted on the torsion tube along the axis of the shaft (as in the first embodiment) and moved by means of one or more actuators. The actuators can, for example, be mounted on the torsion tube by being fixed to it and connected to the arms to move them. For example, the same actuator can be connected to several stators. Preferably, the actuators will be configured to ensure simultaneous movement of the different arms. [Fig. 10] illustrates such a configuration. The magnets can, for example, be permanent magnets rather than electromagnets. In a variant of [Fig.

[10] , a single stator consisting of a single branch will be the only one associated with the different rotors so that the stator as a unit can then move relative to the rotors.

[0153] For example, the stators of the third embodiment or the stator of the second embodiment may have only one branch as in the first embodiment (the associated rotor is then no longer framed on either side by the stator in question).

[0154] Regardless of the embodiment considered, the transmission mechanism may differ from what has been indicated. Thus, although here the transmission mechanism is of the single-stage epicyclic type, the transmission mechanism may be of the multi-stage epicyclic type. The gears within said transmission mechanism may be spur and / or helical. The mechanism may not include a central sun gear or an internally toothed ring gear. Said ring gear may have external teeth and / or the central sun gear may have internal teeth. The central sun gear and / or the internally toothed ring gear and / or the planet carrier may be mounted on the shaft or on the wheel to be braked. For example, [Fig. 1 1] illustrates a variant in which the central sun gear is mounted on the wheel to be braked and no longer on the shaft as in the third embodiment.Preferably, the central planetary gear is then supported by the hub rather than the rim, as the hub is less prone to deformation.

[0155] Regardless of the embodiment considered, the magnets may be carried by the rotor instead of the stator. Figure 12 shows a wheel equipped with a braking device in which the rotor 3 carries the magnets 4, the stator 2 being made of an electrically conductive material.

[0156] Regardless of the embodiment considered, the transmission system 10 which links the rotor 3 to the rim 105 in rotation may be a multiplication mechanism (i.e. its transmission ratio is greater than 1) so that the associated rotor can have a rotational speed greater than that of the wheel or a reduction mechanism (i.e. its transmission ratio is less than 1) so that the associated rotor can have a rotational speed lower than that of the wheel. With reference to [Fig. 12], the transmission system 10 which links the rotor 3 to the rim 105 in rotation is thus optionally a reducer, that is to say that its transmission ratio is less than 1, so that the rotational speed of the rotor 3 is less than the rotational speed of the rim and therefore of the wheel 103.

[0157] Regardless of the embodiment considered, the rotor may be connected to the shaft and the stator to the wheel in the reverse order of what has been described. The rotor may thus form the ring and the stator the annular disc.

[0158] Regardless of the embodiment considered, the shape, arrangement, and dimensions of the magnets may differ from those described or illustrated. For example, the magnets may have different dimensions and / or be arranged according to a Halbach pattern.

[0159] Regardless of the embodiment considered, the magnets and the opposing magnetic material can be arranged to produce between a stator and a rotor a purely axial flux as described above, or a purely radial flux, or even a "radial" magnetic flux (i.e., a magnetic flux that is both radial and axial). For example, [Fig. 10] illustrates a configuration with a purely radial flux. In this case, the rotor is configured so as to have an annular edge coaxial with the rotor's axis of rotation and extending straight along said axis. In operation, this edge extends within a corresponding groove formed by at least one stator magnet, the groove extending circumferentially over 360 degrees or less (the depth of the groove thus being defined along the rotor's axis of rotation).

[0160] Regardless of the embodiment considered, the magnets may be electromagnets instead of permanent magnets.

[0161] Regardless of the embodiment considered, the number of rotors and / or the number of stators may differ from those mentioned. Several rotors axially offset from one another and several stators axially offset from one another may thus cooperate to generate braking eddy currents. Regardless of the embodiment considered (and even in the third, fourth, or fifth embodiment), the magnetic braking device may comprise a single rotor and / or a single stator.

[0162] Regardless of the embodiment considered, if the stator (respectively the rotor) has branches, the number of branches may be at least two. Thus, at least one stator (respectively one rotor) may comprise three (or more) branches providing between them two (or more) grooves, each receiving a portion of a rotor (respectively a stator).

[0163] Regardless of the embodiment considered, the device may include means of guiding the translation of the stator relative to the rotor (respectively of the rotor relative to the stator). For example, the torsion tube may be provided with guides along which the stator (respectively the rotor) will be mounted to slide.

[0164] Regardless of the embodiment considered, the actuators may include: - hydraulic or electromechanical actuators, - linear actuators, - rotary actuators having, for example, an output pinion meshing with a rack and pinion system linked to the crown sector, - single-acting actuators (an elastic element ensuring return to the free rotation position) or double-acting actuators, - or others.

[0165] Regardless of the embodiment considered, the same wheel may be equipped with both a device according to the invention and an additional braking device, for example, a prior art braking device such as a friction braking device. For example, the magnetic braking device will extend in front of the entrance to the annular space, outside of it, and the additional braking device will extend inside said annular space. Figure 2 illustrates such a configuration, it being understood that the additional braking device may also be associated with the braking device according to another embodiment of the invention. The friction braking device may comprise friction elements, for example, a stack of carbon discs housed in the annular space, and a plurality of electromechanical actuators mounted on an actuator holder.Each electromechanical actuator will include an electric motor and a pusher that can be moved by the electric motor to press the stack of discs. The electromechanical actuator will thus be designed to produce a controlled braking force on the stack of discs. A method for controlling the braking devices is, for example, described in document FR-A-2953196.

[0166] Each crown sector may extend over less than 90° or more than 90°. The number of crown sectors may be less than four, for example two or three, or more than four, for example six.

[0167] The crown sectors can be engaged on an outer or inner perimeter of the disk.

[0168] Each angular subsector may extend over less than 25° or more than 25°. The number of angular subsectors may be equal to four, less than four, for example two or three, or more than four, for example six.

[0169] The actuator body may be a single piece with the torsion tube. The torsion tube may have any suitable shape.

[0170] It is possible to use, for the mechanical actuation of the braking device ma In genetics, an actuator acts on several crown sectors, rather than one actuator for each crown sector. A single actuator can thus act on two diametrically opposed crown sectors to move them in opposite directions.

[0171] The number of satellites may be three or four, as illustrated, or may be greater (for example, five) or lesser (for example, two). Regardless of the embodiment envisaged, the number of satellites will preferably be at least three and even more preferably at least four.

[0172] For each element that has been described as being rotationally fixed to the torsion tube (satellite carrier, planetary gear, actuator, ring gear, ...), said element may be fixed to another part arranged to be rotationally linked to a wheel support shaft (such as a shaft guard) or be directly rotationally fixed to said shaft.

Claims

Claims

1. Wheel (103), intended to be supported by a shaft (102), the wheel comprising an eddy current magnetic braking device (1), the device comprising at least one stator (2) and at least one rotor (3), and magnets (4) integral with one of these to produce between them a magnetic flux capable of generating eddy currents in the other of these when the wheel rotates, the wheel being characterized in that the rotor is linked in rotation to the wheel by means of a movement transmission mechanism (10).

2. A wheel according to claim 1, wherein the transmission mechanism (10) is arranged so that the rotor has a speed greater than a rotational speed of the wheel.

3. A wheel according to claim 1, wherein the transmission mechanism (10) is arranged so that the rotor has a speed lower than a rotational speed of the wheel.

4. Wheel according to claim 1, in which the transmission mechanism (10) comprises an internally toothed crown (11) arranged to be integral with the rotor coaxially thereto, a planet carrier (12) arranged to be integral with the rim (105) coaxially thereto and which carries planets (13) meshing with the internally toothed crown (11), and a central sun gear (14) with external teeth meshing with the planets (13) and carrying the rotor (3).

5. Wheel according to claim 1, in which the transmission mechanism (10) comprises an internally toothed crown (11) arranged to be secured to the rim (105) coaxially therewith, a planet carrier (12) which is intended to be secured to the shaft (102), the planet carrier carrying planet gears (13) meshing with the internally toothed crown (11), and a central sun gear (14) with external teeth meshing with the planet gears (13) and carrying the rotor (3).

6. Wheel according to claim 1, in which the transmission mechanism (10) comprises an internally toothed crown (11), a planet carrier (12) which is intended to be integral with the shaft (102), the planet carrier carrying satellites (13) meshing with the internally toothed crown (11), the rotor (3) being carried by one of the satellites.

7. Wheel according to claim 6, in which the magnetic braking device (1) comprises several rotors (3) each carried by one of the satellites (13).

8. Wheel according to claim 7, in which the magnetic braking device (1) comprises as many stators (2) as rotors (3), each stator being mounted level with one of the rotors coaxially therewith.

9. Wheel according to one of claims 5 to 8, in which the internally toothed crown (11) is arranged to be integral with the rim (105) coaxially therewith.

10. A wheel according to one of the preceding claims, wherein the at least one rotor (3) rotates about an axis of rotation which is parallel to and offset from an axis of rotation of the wheel.

11. Wheel according to one of the preceding claims, in which the at least one rotor (3) comprises at least one face extending opposite a face of the stator (2), the face in which eddy currents are generated being of smaller dimensions than the opposite face.

12. A wheel according to claim 11, wherein the rotor (3) and the stator (2) are shaped so that eddy currents are generated in only one angular segment of the stator or rotor.

13. Wheel according to one of the preceding claims, wherein one of the rotor (3) and the stator (2) is a disc and the other of the rotor (3) and the stator (2) is a crown divided into at least two crown sectors (2A, 2B, 2C, 2D) radially movable between a first position in which each crown sector (2A, 2B, 2C, 2D) has at least one face (2.1, 2.2) facing a face (3.1, 3.2) of the disc to establish the magnetic flux and a second position in which said at least one face (2.1, 2.2) of the crown sector (2A, 2B, 2C, 2D) is radially offset relative to the face (3.1, 3.2) of the disc to interrupt the magnetic flux, the device (1) comprising at least one actuator (6) connected to the crown sectors (2A, 2B, 2C, 2D) to move the crown sectors (2A, 2B, 2C, 2D) between their two positions.

14. Landing gear (101) comprising a leg having one end carrying the shaft (102) on which is mounted the hub (104) of a wheel (103) according to any one of the preceding claims.

15. Aircraft (100) comprising at least one landing gear (101) according to claim 14.

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