FR3147556A1 - Wheel with magnetic braking device, aircraft landing gear, and aircraft equipped with such a wheel - Google Patents

Abstract

Wheel, comprising an eddy current magnetic braking device, the device comprising at least one stator and at least one rotor, and magnets secured 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. According to the invention, the rotor is linked in rotation to the wheel by means of a wheel reduction mechanism, device arranged so that the rotor has a speed greater than a rotation speed of the wheel. Landing gear comprising such a wheel. FIGURE OF THE ABSTRACT: Fig. 8

Description

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

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

The present invention relates to a wheel carrying a magnetic braking device, and an aircraft landing gear equipped with such a wheel.

BACKGROUND OF THE INVENTION

An aircraft wheel typically consists of 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).

Friction braking devices are known comprising a stack of brake disks which is housed in an annular space extending between the rim and the hub and which comprises an alternation of rotor disks linked in rotation with the wheel and stator disks 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 disks so as to generate a braking torque to brake the rotation of the wheel.

Eddy current magnetic braking devices are also known, used for braking vehicle wheels and more particularly aircraft wheels.

Document FR-A-3122405 describes such a device comprising a rotor rotationally connected to the wheel, two stators which surround the rotor and which are rotationally connected to the wheel support shaft and free in translation relative to said shaft, magnets for producing an axial magnetic flux between the stators and the rotor, and linear actuators for axially moving the stators between a maximum braking position in which the stators are close to the rotor and a position of free rotation of the wheel in which the stators are distant from the rotor.

However, even in the maximum braking position, the performance of the eddy current magnetic braking device is not satisfactory in the case where the aircraft carrying said device is traveling at low speed.

Furthermore, generally speaking, the performance of an eddy current magnetic braking device depends on the power of the magnets used and their dimensions. However, mass and size are severe constraints and therefore not compatible with an aeronautical application.

SUBJECT OF THE INVENTION

The invention aims in particular to propose a braked wheel which at least partially overcomes the aforementioned drawbacks.

For this purpose, according to the invention, a wheel is provided, intended to be supported by a shaft, the wheel comprising an eddy current magnetic braking device, the device comprising at least one stator and at least one rotor, and magnets secured 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.

According to the invention, the rotor is rotationally connected to the wheel by means of a wheel reduction mechanism, said mechanism being arranged so that the rotor has a rotation speed greater than a rotation speed of the wheel.

Thanks to the reduction mechanism, the rotor remains at a rotation speed higher than that of the wheel, which allows the magnetic braking device to be used at a lower rotation speed of the wheel than with the devices of the prior art.

The magnetic braking device thus proves to be more efficient while maintaining a standard size and weight for this type of device, and without it becoming more complex.

Optionally, the reduction mechanism comprises a crown with internal teeth arranged to be secured to the rotor coaxially thereto, a planet carrier arranged to be secured to the rim coaxially thereto and which carries planets meshing with the crown with internal teeth, and a central sun gear with external teeth meshing with the planets and carrying the rotor.

Optionally, the reduction mechanism comprises a crown with internal teeth arranged to be secured to the rim coaxially therewith, a planet carrier which is intended to be secured to the shaft, the planet carrier carrying planets meshing with the crown with internal teeth, and a central sun gear with external teeth meshing with the planets and carrying the rotor.

Optionally, the reduction mechanism includes an internally toothed crown, a planet carrier which is intended to be secured to the shaft, the planet carrier carrying planets meshing with the internally toothed crown, the rotor being carried by one of the planets.

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

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

Optionally, the internally toothed crown is arranged to be secured to the rim coaxially with it.

Optionally the rotor rotates around an axis of rotation which is parallel and offset from an axis of rotation of the wheel.

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

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

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

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

Optionally, the rotor and stator are arranged so that the magnetic flux likely to generate eddy currents is an axial flux.

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

The invention relates to an aircraft comprising at least one landing gear as mentioned above.

Other characteristics and advantages of the invention will emerge from reading the following description of particular and non-limiting embodiments of the invention.

Reference will be made to the attached drawings, including:

there is a partial schematic front view of an aircraft equipped with landing gear according to the invention;

there is a partial schematic view of a wheel according to a first embodiment of the invention, in axial half-section;

there is a front view of part of a gear reduction mechanism of the wheel illustrated in ;

there is a front view of another part of the gear reduction mechanism of the wheel illustrated in ;

there 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 position of free rotation of the wheel;

there is a schematic perspective view of the wheel shown in , the crown sectors being in their second position;

there is a schematic perspective view of the wheel shown in , the crown sectors being in their first position or maximum braking position;

there is a schematic perspective view of a wheel according to a third embodiment of the invention;

there is a partial schematic view of the wheel illustrated in , in axial half-section;

there is a schematic perspective view of a wheel according to a fourth embodiment of the invention;

there is a partial schematic view of the wheel according to a fifth embodiment of the invention, in axial half-section.

DETAILED DESCRIPTION OF THE INVENTION

There represents an aircraft 100 comprising landing gears 101.

At least one of the landers 101 comprises a leg having one end provided here with 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 axis X of rotation of the wheel 103 which it carries.

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 web 106. The rim 105 and the hub 104 define between them an annular space 107 having one end closed by the web 106 and one end open towards the outside of the wheel 103 forming an entrance to the annular space 107. The rim 105 is surrounded by a tire, not shown, received between two lips 108 of the rim 105.

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

The magnetic braking device 1 extends, for example, in front of the entrance to the annular space 107, outside the latter.

With reference to Figures 2 to 4, a first embodiment will now be described.

The magnetic braking device 1 comprises a fixed element, or stator 2, and a mobile element, or rotor 3.

The stator 2 is the part of the device linked in rotation to the shaft 102 or to the leg of the landing gear 101, here by means of a torque tube 5.

The torque tube 5 comprises a body 5.1 engaged on an external collar 102’ of the shaft 102, and an internal collar 5.2 which is fixed (for example by screws) to the collar 102’.

Preferably, the stator 2 is mounted on the torque tube 5 so as to also be able to slide axially (i.e. parallel to the X axis) along said torque tube 5 and therefore along the shaft 102 or the leg of the landing gear 101.

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

The actuator is optionally connected to the stator 2 via a plate 7. More precisely here, the body of each actuator 6 receives a sliding piston which is movable in translation in 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 landing gear) and thus move closer to or further away from the wheel 103.

The stator 2 can then be moved between a maximum braking position in which the stator 2 is close to the rotor 3 and a position of free rotation of the wheel 103 in which the stator 2 is moved away from the rotor 3.

Furthermore, the stator 2 preferably has a crown shape coaxial with the wheel 103 and the shaft 102.

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

The magnets 4 generate magnetic fields to produce a magnetic flux in the direction of the rotor 3 located opposite, that is to say an axial magnetic flux parallel to the X axis.

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.

In the present case, the rotor 3 has the shape of an annular disk coaxial with the wheel 103 and the shaft 102.

The magnetic braking device comprises a reduction mechanism 10 by means of which the rotor 3 is rotatably connected to the wheel 103. The reduction mechanism 10 is such that the rotor 3 has, in service, a rotation speed greater than a rotation speed of the wheel 103.

The reduction mechanism 10 is here of the epicyclic type.

The reduction mechanism 10 thus comprises an internally toothed crown 11 (visible in the ) arranged to be integral with the rotor 3 coaxially thereto. The internally toothed crown 11 thus carries the rotor 3 so that it is opposite the stator 2 coaxially with the stator 2.

The reduction mechanism 10 also comprises a planet carrier 12 and satellites 13, carried by the planet carrier 12 and meshing with the internally toothed crown 11. The planet carrier 12 is secured to the rim 105 coaxially therewith.

The reduction gear mechanism also includes a central planetary gear 14 with external teeth, illustrated in , meshing with the satellites 13.

The central planetary gear 14 is here part of the torque tube 5. The central planetary gear 14 thus internally forms at least one part of the body 5.1.

The central planetary gear 14 is thus rotationally integral with the shaft 102 and coaxial with said shaft 102.

Furthermore, the central planetary gear 14 has an external first section 14.1 provided with external teeth for engagement with the satellites 13.

The central planetary gear 14 comprises externally, 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.

The rotor 3 is therefore linked in rotation to the wheel 103 by means of the rim 105 and the reduction mechanism 10.

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).

• une première position, ou position de freinage maximal de la roue 103, dans laquelle le stator 2 est rapproché du rotor 3, et ;
• une deuxième position, ou position de rotation libre de la roue 103, dans laquelle le stator 2 est écarté du rotor 3.

The actuator 6 moves the stator 2 in 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 close to the rotor 3, and;
• a second position, or free rotation position of the wheel 103, in which the stator 2 is spaced from the rotor 3.

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

Thanks to the reduction mechanism, the rotor 3 remains at a rotation speed higher than that of the wheel 103, which allows the magnetic braking device 1 to be used at a lower rotation speed of the wheel 103 than in the prior art.

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

It is understood that to cause braking, the actuator 6 is controlled to bring the stator 2 into the first position and that, 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 cause braking of the rotor 3.

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

Other variants are conceivable within the framework of the invention.

With reference to Figures 5 to 7, a second embodiment will now be described.

Unlike the first embodiment, in which the stator 2 and the rotor 3 could be moved closer to or further away from each other 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.

For this purpose, the stator 2 is divided into four crown sectors 2A, 2B, 2C, 2D, identical to each other, 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 branches facing each other. Each branch preferably comprises a non-magnetic support provided with a plurality of magnets 4, for example permanent magnets, having free faces (opposite the branch which carries them) and generating magnetic fields to produce a magnetic flux in the direction of the branch located opposite, that is to say an axial magnetic flux parallel to the axis X. The two branches of each crown sector 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.

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

In this second embodiment, the actuators 6 are eight in number, arranged in pairs at 90° to each other and each crown 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 in opposition to the actuators 6 of the pair of actuators which is at 180° relative to them. The actuators 6 may have a body fixed to the external collar 5.3 of the torque tube 5 but here have a body 6.1 in a single piece with the external collar 5.3 of the torque tube 5. The body 6.1 of each actuator 6 slidably receives a piston 6.2 which is movable in translation in a radial direction and which has a free end section on which is fixed one of the branches 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.

The rotor 3 always has the shape of an annular disk coaxial with the wheel 103 and the shaft 102.

The rotor 3 is still rotationally connected to the rim 105 of the wheel 103 by means of a reduction mechanism 10 arranged so that the rotor 3 has a speed greater than a rotation speed of the wheel 103.

In this second embodiment, the internally toothed crown 11 is arranged to be secured to the rim coaxially therewith, the planet carrier 12 is secured to the torque tube 5 and the central sun gear 14 with external teeth carries the rotor 3 and is secured to said rotor 3. The central sun gear 14 is thus mounted to pivot on a bearing surface of the planet carrier 12 and/or the torque tube 5.

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

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

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 gear 14, and rotates on itself around its central axis relative to the ring gear sectors 2A, 2B, 2C, 2D which surround it: during this movement of the rotor 3 in a circumferential direction relative to the ring gear sectors 2A, 2B, 2C, 2D, the main faces 3.1, 3.2 remain parallel to the main faces 2.1, 2.2.

• une première position, ou position de freinage maximal de la roue 103, dans laquelle les secteurs de couronne 2A, 2B, 2C, 2D du stator 2 sont rapprochés du rotor 3, les secteurs de couronne 2A, 2B, 2C, 2D chevauchant un pourtour externe du rotor 3, de sorte que les faces 2.1, 2.2 du stator 2 s’étendent en regard des faces 3.1, 3.2 du rotor 3 en étant séparées de celles-ci par un premier entrefer prédéterminé et ;
• une deuxième position, ou position de rotation libre de la roue 103, dans laquelle les secteurs de couronne 2A, 2B, 2C, 2D du stator 2 sont écartés du rotor 3, les secteurs de couronne 2A, 2B, 2C, 2D étant dégagés du pourtour externe du rotor 3, de sorte que les faces 2.1, 2.2 du stator 2 sont décalées radialement vers l’extérieur par rapport aux faces 3.1, 3.2 du rotor 3 et sont séparées des faces 3.1, 3.2 par un deuxième entrefer prédéterminé supérieur au premier entrefer prédéterminé.

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 closer 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 while being separated from the latter 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 spaced from the rotor 3, the crown sectors 2A, 2B, 2C, 2D being clear of the external periphery of the rotor 3, so that the faces 2.1, 2.2 of the stator 2 are offset radially 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 air gap greater than the first predetermined air gap.

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.

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 opposite the magnets 4.

The rotor 3 has a thickness such that a skin effect (otherwise called a skin effect or Kelvin effect) is generated from each face 3.1, 3.2 of the rotor 3 over more than half of the thickness of the rotor 3 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 gives in the central part a “superposition of the skin effects” produced from each face 3.1, 3.2, the thickness of the rotor 3 being sufficiently small to obtain this superposition while satisfying the thermal and mechanical constraints. In one example, this superposition gives approximately 60% more performance.

It will be noted that the branch of each angular sector arranged on the side of face 3.2 provides a heat 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.

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

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

With reference to Figures 8 to 9, a third embodiment will now be described.

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 portion of the rotor 3 is subjected to the magnetic flux of the stator 2.

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

The rotors 3 are made of electrically conductive materials. The rotors 3 are for example made of metallic material and for example made of copper, aluminum, silver, nickel, etc.

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

The magnetic braking device 1 here again comprises a reduction mechanism 10 by means of which the rotors 3 are linked in rotation to the wheel 103. The reduction mechanism is such that the different rotors 3 have, in service, a rotation speed greater than a rotation speed of the wheel 103.

The reduction mechanism 10 is here of the epicyclic type.

The reduction mechanism 10 thus comprises an internally toothed crown 11 arranged to be secured to the rim 105 coaxially therewith.

The reduction mechanism 10 also comprises a planet carrier 12 and planets 13, carried by the planet carrier 12 and meshing with the internally toothed crown 11. The planet carrier 12 is integral with the shaft 102 coaxially therewith. For example, the planet carrier 12 is fixed to the shaft 102 by means of a torque tube 5. The torque tube comprises a body 5.1 engaged on an external collar 102' of the shaft 102, and an internal collar 5.2 which is fixed (for example by screws) to the external collar 102'. The planet carrier 12 itself is fixed to the internal collar 5.2 (on a face of said collar opposite that attached to the external collar 102' of the shaft 102) for example by means of screws.

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

The reduction mechanism also comprises a central sun gear 14 with external teeth meshing with the satellites 13. The central sun gear 14 is mounted to pivot on a bearing surface of the planet carrier 12 and/or the torque tube 5.

The rotor 3 is therefore linked in rotation to the wheel 103 by means of the rim 105 and the reduction mechanism 10.

It is therefore understood that, as for the first two embodiments, the stators 2 are here the part of the device linked in rotation to the shaft 102 or to the leg of the landing gear 101. In the present case, the stators 2 are linked in rotation to the shaft 102 by means of the torque tube 5. The stators 2 are for example mounted on the body 5.1 of the torque tube 5 and for example fixed to said body 5.1.

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

Each stator 2 is here shaped into an angular sector with an opening angle of between 90 and 200 degrees, and for example between 120 and 190 degrees. Each stator 2 is here shaped into a half-crown (i.e. an angular sector with an opening angle of 180 degrees).

More precisely here, each stator 2 has a cross-section (according to a section plane containing the X axis) with two branches facing each other. The two branches are here 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 indicated previously.

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

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 carrying it.

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

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.

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.

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

Each rotor 3 thus has two faces 3.1, 3.2, main and opposite to each other, between which extends parallel a median plane merged with a median plane of the groove extending parallel and halfway 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 moreover carried by one of the satellites 13 to be coaxial with the associated stator 2 and to be surrounded by said stator 2.

As already indicated, the rotors 3 are linked in rotation to the wheel 103, here to the rim 105 of the wheel 103 by means of the satellites 13, and rotate on themselves around their central axis relative to the associated stator 2 which surrounds it. During this movement of the rotor 3 in a circumferential direction relative to the branches of the stator 2 which surrounds it, the main faces 3.1, 3.2 remain parallel to the main faces 2.1, 2.2.

The different rotors 3 therefore extend such that their main 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 different stators extend such that their main 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).

The magnetic braking device 1 comprises or carries a supply member (not shown here) for the electromagnets forming here the magnets 4.

• une valeur d’alimentation maximale, correspondant à un freinage maximal de la roue 103, et ;
• une valeur d’alimentation nulle, correspondant à une rotation libre de la roue 103.

The power supply unit can modulate the electrical supply to the electromagnets between:

• a maximum power supply value, corresponding to maximum braking of the wheel 103, and;
• a zero power supply value, corresponding to free rotation of the wheel 103.

When the electromagnets are energized, 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 opposite the magnets 4.

Advantageously, these eddy currents are generated in only one 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 framed 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 plays the role of heat sink. Indeed, the eddy currents cause the rotor 3 to heat up: the complementary angular segment in contact with the surrounding air can therefore evacuate this heat. Advantageously, this evacuation is done by forced convection due to the rotation of the rotor.

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

Advantageously, the rotors 3 rotate at a higher rotation speed than the wheel 103, which further promotes this forced convection.

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.

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 heat shield function, said branch being in fact arranged between the rotor 3 and the rest of the magnetic braking device 1.

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

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

It is further noted that the rotation speed of the rotors 3 is proportional to that of the wheel 103 to be braked.

Preferably, each rotor 3 has a thickness such that a skin effect (otherwise called a skin effect or Kelvin effect) is generated from each face 3.1, 3.2 of the rotor 3 over more than half of 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 relative 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. This gives in the central part a “superposition of the skin effects” produced from each face 3.1, 3.2, the thickness of the rotor 3 being sufficiently small to obtain this superposition while satisfying the thermal and mechanical constraints. In one example, this superposition gives approximately 60% more performance.

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

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.

The invention can be used on any type of vehicle, for example a land vehicle or an air or amphibious vehicle.

The invention can be used for applications other than a vehicle and for example for any industrial or personal equipment requiring braking.

The magnetic braking device may have a different structure than that described.

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

For example, in the third embodiment, it will be possible to have a stator associated with several rotors, or even with all the rotors, as in the first embodiment or the second embodiment.

For example, the stator and/or the rotor of the first embodiment or the second embodiment may be shaped such that eddy currents are generated only in one 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).

For example, the stators of the third embodiment may be mounted on the torque tube so as to be able to be moved closer to or further away from the rotors to modulate the braking force as in the first embodiment or the second embodiment. For example, at least one of the branches of each stator may be slidably mounted on the torque tube along the axis of the shaft (as in the first embodiment) and moved by means of one or more actuators. The actuators may for example be carried by the torque tube by being fixed to it and connected to the branches in order to be able to move them. For example, the same actuator may be connected to several stators. Preferably, the actuators will be configured to ensure simultaneous movement of the different branches. illustrates such a configuration. The magnets could, for example, be permanent magnets and no longer electromagnets. In a variant of the , a single stator formed from a single branch will be the only one associated with the different rotors so that the stator of a block can then move relative to the rotor.

For example, the stators of the third embodiment or the stator of the second embodiment may comprise only one branch as in the first embodiment (the associated rotor then no longer being framed on either side by the stator considered).

Regardless of the embodiment considered, the gear reduction mechanism may be different from what has been indicated. Thus, although here the gear reduction mechanism is of the single-stage epicyclic type, the gear reduction mechanism may be of the multi-stage epicyclic type. The gears within said gear reduction mechanism may be straight and/or helical. The mechanism may not include a central sun gear or an internally toothed crown gear. Said crown gear may have external teeth and/or the central sun gear internal teeth. The central sun gear and/or the internally toothed crown gear and/or the planet carrier may be carried by the shaft or by the wheel to be braked. For example, the illustrates a variant in which the central planetary gear is carried by the wheel to be braked and no longer by the shaft as in the third embodiment. Preferably, the central planetary gear is then carried by the hub rather than by the rim, the hub being less subject to deformation.

Whatever the embodiment considered, the magnets can be carried by the rotor instead of the stator.

Whatever the embodiment considered, the rotor can be connected to the shaft and the stator to the wheel, in the opposite way to what has been described. The rotor can thus form the crown and the stator the annular disk.

Regardless of the embodiment considered, the shape, arrangement and dimensions of the magnets may be different from those described or shown. For example, the magnets may have different dimensions and/or be arranged according to a HALBACH pattern.

Regardless of the embodiment considered, the magnets and the facing magnetic material may be arranged to produce between a stator and a rotor a solely axial flux as described, or a solely radial flux or even a “raxial” magnetic flux (i.e. a magnetic flux that is both radial and axial). For example, the illustrates a configuration with purely radial flux. In this case, the rotor is configured so as to have an annular edge coaxial with the axis of rotation of the rotor and extending rectilinearly along said axis. This edge extends in use inside a corresponding groove formed by at least one magnet of the stator, groove extending circumferentially over 360 degrees or less (the depth of the groove thus being defined along the axis of rotation of the rotor).

Whatever the embodiment considered, the magnets may be electromagnets instead of permanent magnets.

Regardless of the embodiment considered, the number of rotors and/or the number of stators may be different from those mentioned. Several rotors axially offset from each other and several stators axially offset from each other may thus cooperate together to generate braking eddy currents. Regardless of the embodiment considered (and even in the third embodiment or the fourth embodiment or the fifth embodiment), the magnetic braking device may comprise a single rotor and/or a single stator.

Regardless of the embodiment considered, if the stator (respectively the rotor) comprises branches, the number of branches may be equal to at least two. Thus at least one stator (respectively one rotor) may comprise three branches (or more) forming between them two grooves (or more) each accommodating a portion of a rotor (respectively one stator).

Whatever the embodiment considered, the device may comprise means for guiding the stator in translation relative to the rotor (respectively the rotor relative to the stator). For example, the torque tube may be provided with guides along which the stator (respectively the rotor) will be mounted to slide.

• des actionneurs hydrauliques ou électromécaniques,
• des actionneurs linéaires,
• des actionneurs rotatifs ayant par exemple un pignon de sortie engrenant avec une crémaillère liée au secteur de couronne,
• des actionneurs à simple effet (un élément élastique assurant le rappel en position de rotation libre) ou à double effet,
• ou autres.

Whatever 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 linked to the crown sector,
• single-acting actuators (an elastic element ensuring return to the free rotation position) or double-acting actuators,
• or others.

Whatever 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 braking device of the prior art 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. 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 members, for example a stack of carbon discs housed in the annular space, and a plurality of electromechanical actuators carried by an actuator holder. Each electromechanical actuator will comprise an electric motor and a pusher capable of being moved by the electric motor to press the stack of discs. The electromechanical actuator will thus be intended to produce a controlled braking force on the stack of discs. A method of controlling the braking devices is for example known from document FR-A-2953196.

Each crown sector may extend 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.

The crown sectors can be engaged on an external periphery or an internal periphery of the disc.

Each angular sub-sector may extend over less than 25° or more than 25°. The number of angular sub-sectors may be equal to four, less than four, for example two or three, or greater than four, for example six.

The actuator body may be in one piece with the torque tube. The torque tube may have any suitable shape.

It is possible to use, for the mechanical actuation of the magnetic braking device, an actuator acting on several ring sectors, rather than an actuator for each ring sector. A single actuator can thus act on two ring sectors diametrically opposed to each other to move them in opposite directions.

The number of satellites may be three or four as illustrated or may be greater (and be for example five) or less (and be for example two). Whatever the embodiment envisaged, the number of satellites will preferably be at least three and more preferably at least four.

For each element which has been described as being integral in rotation with the torque tube (planet carrier, sun gear, actuator, crown, etc.), said element may be integral with another part arranged to be linked in rotation to a wheel support shaft (such as a shaft guard) or be directly integral in rotation with said shaft.

Claims (15)

Wheel, intended to be supported by a shaft, the wheel comprising a magnetic braking device (1) with eddy current, 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 reduction mechanism (10) of the wheel, said mechanism being arranged so that the rotor has a speed greater than a rotation speed of the wheel. Wheel according to claim 1, in which the reduction 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). Wheel according to claim 1, in which the reduction 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). Wheel according to claim 1, in which the reduction mechanism (10) comprises an internally toothed crown (11), a planet carrier (12) which is intended to be secured to the shaft (102), the planet carrier carrying planets (13) meshing with the internally toothed crown (11), the rotor (3) being carried by one of the planets. Wheel according to claim 4, in which the magnetic braking device (1) comprises several rotors (3) each carried by one of the satellites (13). Wheel according to claim 5, 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. Wheel according to one of claims 3 to 7, in which the internally toothed crown (11) is arranged to be secured to the rim (105) coaxially therewith. Wheel according to one of the preceding claims, wherein the rotor (3) rotates about an axis of rotation which is parallel to and offset from an axis of rotation of the wheel. Wheel according to one of the preceding claims, in which the 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. Wheel according to claim 9, 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. Wheel according to one of the preceding claims, wherein one of the rotor (3) and the stator (2) is a disk 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) movable radially 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 disk to establish the axial 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 offset radially relative to the face (3.1, 3.2) of the disk to interrupt the axial magnetic flux, the device (1) comprising at least one actuator (6) connected to the crown sectors (2A, 2B, 2C, 2D) ... 2C, 2D) to move the crown sectors (2A, 2B, 2C, 2D) between their two positions. Wheel according to one of the preceding claims, comprising a rim (105) and a hub (104) connected by a web (106) defining an annular space (107), the braking device (1) being placed in front of an entrance to the annular space (107), the crown (11) being intended to be secured to the shaft (102). Wheel according to one of the preceding claims, the rotor (3) and the stator (2) are arranged so that the magnetic flux capable of generating eddy currents is an axial flux. 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. Aircraft (100) comprising at least one landing gear (101) according to claim 14.