Wheel with combined magnetic / friction braking for a vehicle, and aircraft landing gear and aircraft which are provided with such a wheel

Abstract

The invention relates to a braked wheel (1) mounted on an axle (E) so as to be rotatable about an axis (X), comprising: − a first, magnetic braking device (10) comprising a stator (11) and a rotor (12) capable of producing a first braking torque, one of the stator and the rotor being arranged to move along the axis (X) between a position of free rotation and a braking position and to be returned to the position of free rotation by elastic return means; − a second, friction braking device (20) comprising a stack of discs (21.1, 21.2, 21.3, 22.1, 22.2) capable of producing a second braking torque on the wheel, the stack of discs comprising a rear face axially facing the stator or the rotor arranged to move along the axis; and - at least one actuator (41) designed to exert a pressing force on a front face of the stack of discs.

Description

[0001] MIXED MAGNETIC / FRICTION BRAKING WHEEL FOR VEHICLE, AIRCRAFT LANDING GEAR AND AIRCRAFT EQUIPPED WITH SUCH A WHEEL

[0002] The present invention relates to the field of braking vehicle wheels such as aircraft wheels. The invention applies more particularly to mixed magnetic / friction braking devices, i.e. devices in which a magnetic field and mechanical friction are used simultaneously or selectively to produce a braking force.

[0003] BACKGROUND OF THE INVENTION

[0004] An aircraft wheel typically comprises a rim connected by a web to a hub which is mounted for rotation on an axle carried by a lower end of a landing gear. The aircraft wheel is traditionally provided with a braking device to slow and stop the aircraft when it is on the ground.

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

[0006] Eddy current magnetic braking devices are also known, used for braking vehicle wheels and more particularly aircraft wheels. The magnetic braking device generally comprises a rotor which is attached to the wheel opposite a stator mounted to slide relative to the axle. One of the rotor and the stator is provided with magnets while the other of said rotor and said stator is composed of an electrically conductive material. The sliding of the stator is generally subject to hydraulic or electromechanical actuators arranged to selectively bring said stator closer to the rotor so as to generate a braking torque on said rotor and thus brake the rotation of the wheel. Document FR-A-3122405 describes such a magnetic braking device.

[0007] Unlike friction braking devices, eddy current braking devices are not subject to wear, which limits their maintenance and the emission of fine particles. However, eddy current braking devices can only be used when the rotor has a certain speed relative to the stator. It therefore seemed sensible to combine the magnetic braking device with a friction braking device to ensure braking at low speed or when parking.

[0008] However, this association tends to require the integration of a first control system to actuate the friction braking device, and a second control system, independent of the first control system, to actuate the eddy current braking device, which tends to complicate the control of the brake, but also to increase its weight and complicate its integration into the wheel.

[0009] SUBJECT OF THE INVENTION

[0010] The invention results from this work and aims to propose a vehicle wheel with mixed braking which at least partially overcomes the aforementioned drawbacks.

[0011] SUMMARY OF THE INVENTION

[0012] To this end, the invention proposes a braked vehicle wheel mounted for rotation on an axle about an axis, comprising: - a first magnetic braking device, comprising a stator and a rotor arranged to produce between them a magnetic flux capable of generating eddy currents producing a first braking torque of the wheel, one of the stator and the rotor being arranged to move along the axis of rotation of the wheel between a position of free rotation of the wheel and a braking position of the wheel and to be returned to the position of free rotation by elastic return means;

[0013] - a second braking device, by friction, comprising a stack of discs comprising at least one stator disc and one rotor disc arranged to rub against each other, producing a second braking torque for the wheel, the stack of discs comprising a rear face axially facing the stator or the rotor arranged to move along the axis of rotation of the wheel; and

[0014] - at least one actuator arranged to exert on a front face of the stack of disks a pressing force sufficient to force the stator disk and the rotor disk to rub against each other and cause the stator or the rotor to move from the free rotation position to the braking position.

[0015] The pressing force exerted by the actuator is thus capable of simultaneously producing the first braking torque and the second braking torque, so that a single control system makes it possible to control both the first braking device and the second braking device. The operation and implementation of the wheel braking system are therefore facilitated and simplified, and the overall volume of said braking system is limited.

[0016] According to a particular characteristic, the first braking device is radial flow. According to another particular characteristic, the wheel comprises an annular rim connected by a disc to a hub pivotally received on the axle, the rim delimiting with the disc and the hub an annular space in which the first braking device and the second braking device extend.

[0017] According to another particular characteristic, the elastic return means comprise at least one spring.

[0018] According to another particular characteristic, the stator disc and the rotor disc are slidably mounted along the axis of rotation of the wheel on a torsion tube fixed to the axle.

[0019] In a particular way, the stator is slidably mounted along the axis of rotation of the wheel on the torsion tube.

[0020] According to another special feature, the stator carries magnets.

[0021] According to another particular characteristic, the actuator is a hydraulic actuator.

[0022] The invention also relates to an aircraft landing gear comprising at least one such wheel.

[0023] The invention also relates to an aircraft comprising at least one such landing gear.

[0024] BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The invention will be better understood in light of the following description, which is purely illustrative and not limiting, and must be read in conjunction with the appended drawings, among which:

[0026] [Fig.l] Figure 1 is a simplified representation of an aircraft comprising braked wheels according to a particular embodiment of the invention;

[0027] [Fig.2] Figure 2 is an axial sectional view of one of the braked wheels of the aircraft illustrated in Figure 1;

[0028] [Fig.3] Figure 3 is an exploded view of the wheel illustrated in Figure 2. DETAILED DESCRIPTION OF THE INVENTION

[0029] With reference to Figure 1, the invention is described in application to an aircraft A comprising two main landing gears P which each comprise a leg J ​​having a first end articulated on a structure S of the aircraft A and, opposite, a second end carrying wheels 1 rotating around an axis X on a tubular axle E. The main landing gears P are here of the retractable type but the invention is applicable to fixed landing gears, or even to another type of vehicle such as a land vehicle.

[0030] The wheels 1 are said to be "braked", that is to say equipped with a brake intended to selectively slow down and stop the aircraft A when it is on the ground. The following description relates to one of the wheels 1 of the aircraft, the wheels 1 being identical here but can also be different.

[0031] The wheel 1 comprises, as illustrated in Figure 2, an annular rim 2 connected by a web 3 to a hub 4 pivotally received on the axle E by means of bearings (not shown). The rim 2 extends opposite the hub 4 and delimits with said hub 4 an annular space having one end at least partially closed by the web 3 and, opposite, an open end.

[0032] The wheel brake 1 comprises a first radial flux magnetic braking device 10 and a second friction braking device 20.

[0033] The first braking device 10 comprises a fixed rotating element, or stator 11, and a mobile rotating element, or rotor 12. The stator 11 and the rotor 12 here respectively have the shape of an annular disc and a crown having central axes merged with the axis X of rotation of the wheel 1.

[0034] With reference to Figure 3, the rotor 12 has an external periphery which comprises axial peripheral grooves 12.1 each receiving an end section of a bar 5 fixed on the inner surface of the rim 2 to ensure rotational coupling of the rotor 12 with the rim 2 around the axis X. Screws (not shown) connect the rotor 12 to the end sections of the bars so that said rotor 12 is fixed relative to the wheel 1.

[0035] The crown forming the rotor 12 is made of an electrically conductive material and comprises an internal periphery defining a main surface 12.2 of the rotor 12. This main surface 12.2 is cylindrical in shape and extends coaxially with the wheel 1.

[0036] The stator 11 has an internal periphery which comprises axial peripheral notches 11.1 each receiving a section of a tenon (not shown) or rib which is integral with the external surface of a torque tube 30 fixed to a collar Ei of the axle E to ensure rotational coupling of the stator 11 with the torque tube 30 around the axis X and translational guidance of said stator 11 on the torque tube 30 along said axis X.

[0037] The disc forming the stator 11 comprises an external periphery provided with a series of permanent magnets 11.3 defining a main surface 11.2 of the stator 11. This main surface 11.2 is cylindrical in shape and extends coaxially with the wheel 1 so as to be able to be engaged in the main surface 12.2 of the rotor 12. The magnets 11.3 are arranged so as to generate eddy currents in the rotor 12 when the main surface 11.2 of the stator 11 and the main surface 12.2 of the rotor 12 are separated by a small air gap and said rotor 12 pivots relative to said stator 11.

[0038] The tenons form slides allowing the stator 11 to slide along the X axis on the torque tube 30 between a first position called braking (not shown) and a second position called free rotation of the wheel 1 (shown in Figure 2) towards which said stator 11 is returned by helical springs 13 equally distributed around the X axis. In the braking position, the stator 11 is brought closer to the rotor 12 to the point that the main surface 11.2 of the stator 11 is engaged in the main surface 12.2 of the rotor 12: the main surfaces 11.2, 12.2 are separated from each other by a first predetermined air gap. In the free-rotating position, the stator 11 is spaced from the rotor 12 to the point that the main surface 11.2 of the stator 11 is clear of the main surface 12.2 of the rotor 12: the main surfaces 11.2, 12.2 are separated from each other by a second predetermined air gap which is greater than the first air gap.It is understood that in the braking position, the magnets 11.3 of the stator 11 generate in the rotor 12 sufficient eddy currents to generate a braking torque on said rotor 12, and that in the free rotation position, this braking torque is negligible, or even non-existent.

[0039] The second braking device 20 comprises, in a manner known per se, brake discs, including stator discs 21.1, 21.2, 21.3 and rotor discs

[0040] 22.1, 22.2 which are stacked alternately with each other on the torque tube 30. The stator discs 21.1, 21.2, 21.3 and the rotor discs

[0041] 22.1, 22.2 extend inside the annular space delimited by the wheel 1 and are here made of carbon or steel.

[0042] Referring to Figure 3, the stator discs

[0043] 21.1, 21.2, 21.3 have an internal periphery comprising axial peripheral notches 21a each receiving a section of the tenons secured to the external surface of the torsion tube 30 to ensure rotational coupling of the stator discs 21.1, 21.2, 21.3 with the torsion tube 30 around the axis X.

[0044] The stator discs 21.1, 21.2, 21.3 comprise in particular a first stator disc 21.1 and a last stator disc 21.3 between which the rotor discs 22.1, 22.2 and the other stator disc 21.2 extend.

[0045] The last stator disc 21.3 comprises a friction front face which is axially opposite the rotor disc 22.2, and a rear face, opposite the front face, which is axially opposite the stator 11 of the first braking device 10. It is understood that the first braking device 10 is arranged between the disc 3 of the wheel 1 and the last stator disc 21.3 of the second braking device 20.

[0046] The rotor discs 22.1, 22.2 have an external periphery comprising axial peripheral notches 22a each receiving a section of the bars 5 fixed on the inner surface of the rim 2 to ensure rotational coupling of the rotor discs 22.1, 22.2 with the rim 2 around the axis X.

[0047] The brake further comprises hydraulic actuators 41 (here four in number) which are carried by an actuator-carrying ring 40 fixed to one end of the torque tube 30. The actuators 41 are identical to each other and have centers inscribed on the same circle, the center of which is located on the axis X of rotation of the wheel 1.

[0048] Each of the actuators 41 comprises a piston 41.1 received in a cylindrical cavity 40.1 of the actuator-carrying ring 40. The cavities 40.1 are distributed equally around the axis X of rotation of the wheel 1. The pistons 41.1 are movable in translation along an axis parallel to the axis X of rotation of the wheel 1 to exert on a front face of the first stator disc 21.1 a sufficient pressing force to:

[0049] - causing the stator 11 to move, against the springs 13, from the free rotation position to the braking position by pushing the stack of discs 21.1, 21.2, 21.3, 22.1 against said stator 11, so as to generate a first braking torque on the wheel 1 via the rotor 12; and

[0050] - force all of the discs 21.1, 21.2, 21.3, 22.1, 22.2 to rub against each other so as to generate a second braking torque on the wheel 1 via the rotor discs 22.1, 22.2.

[0051] The equitable distribution of the actuators 41 around the X axis makes it possible to equitably distribute the pressing forces exerted by the pistons 41.1 on the first stator disc 21.1 and indirectly on the stator 11.

[0052] We understand that:

[0053] - the sliding of the stator 11 between the free rotation position and the braking position is subject to the actuators 41 via the stack of discs 21.1, 21.2, 21.3,

[0054] 22.1, 22.2;

[0055] - when the stator 11 is between the free rotation position and the braking position, the second braking torque generated by friction depends on the stiffness of the springs 13;

[0056] - as soon as the stator 11 is in the braking position, the first braking torque generated by the eddy currents is maximum and the second braking torque generated by friction is no longer linked to the stiffness of the springs 13; and

[0057] - the first braking torque and the second braking torque are cumulative.

[0058] We also understand that:

[0059] - when the pressing forces exerted by the actuators 41 on the stack of discs 21.1, 21.2, 21.3,

[0060] 22.1, 22.2 are less than the return forces exerted by the springs 13 on the stator 11 in the free rotation position, said stator 11 remains in the free rotation position so that the first braking torque is negligible (or even non-existent) and the second braking torque is a function of said pressing forces.

[0061] - when the pressing forces exerted by the actuators 41 on the stack of discs 21.1, 21.2, 21.3, 22.1, 22.2 are slightly greater than the return forces exerted by the springs 13 on the stator 11 in the free rotation position, said stator 11 tends to move from the free rotation position to the braking position so that the first braking torque is a function of the stiffness of the springs 13 and the second braking torque is a function of said pressing forces and said stiffness of the springs 13; and

[0062] - when the pressing forces exerted by the actuators 41 on the stack of discs 21.1, 21.2, 21.3, 22.1, 22.2 are significantly greater than the return forces exerted by the springs 13 on the stator 11 in the free rotation position, said stator 11 reaches the braking position so that the first braking torque is maximum and the second braking torque is a function of said pressing forces.

[0063] It is thus possible to have more or less significant friction braking (the second braking device 20 is not necessarily completely engaged) while the magnetic braking is maximum (the first braking device 10 is completely engaged), which makes it possible to use the second braking device 20 more or less and therefore to limit the wear of the discs 21.1, 21.2, 21.3, 22.1, 22.2 in situations where the first braking device 10 is sufficient to slow down the wheel 1.In other words, the second braking device 20 can be used substantially only when necessary, in particular in speed ranges of the wheel 1 where the first braking device 10 is the least effective, or even at energy levels which require the use of both the first braking device 10 and the second braking device 20, for example during a takeoff interruption also called RTO for “Rejected Take Off”.

[0064] It will be noted that the friction of the discs 21.1, 21.2, 21.3, 22.1, 22.2 causes, in a manner known per se, wear of the various rubbing faces of the stator discs 21.1, 21.2, 21.3 and the rotor discs 22.1, 22.2, and therefore a reduction in their thickness. This wear can be compensated by a commonly used compensation device so that the actuation stroke, and therefore the actuation time, of the pistons 41.1 is identical at each new braking, throughout the use and wear of the discs 21.1, 21.2, 21.3, 22.1, 22.2.

[0065] 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.

[0066] Rotor 12 can be integrated into wheel 1.

[0067] Although the first magnetic braking device 10 is here radial flux (the stator 11 and the rotor 12 have only axial surfaces as main surfaces 11.2, 12.2), it can also be axial flux (the stator 11 and the rotor 12 have only radial surfaces as main surfaces) or combine radial and axial fluxes.

[0068] The magnets 11.3 can be carried by the rotor 12 instead of the stator 11. The stator 11 is then made of or covered with an electrically conductive material.

[0069] 11.3 Magnets can be permanent magnets, electromagnets, or a combination of both.

[0070] Although the relative bringing together of the stator 11 and the rotor 12 along the X axis is here achieved by sliding said stator 11 on the torque tube 30, it can also be achieved by sliding said rotor 12 on the rim 2.

[0071] The actuator carrier ring 40 can be fixed directly to the axle E. The torque tube 30 can be fixed to the actuator carrier ring 40.

[0072] The number of stator discs 21.1, 21.2, 21.3 and the number of rotor discs 22.1, 22.2 may be different from those described and illustrated.

[0073] Although the stator discs 21.1, 21.2, 21.3 and the rotor discs 22.1, 22.2 are here made of carbon or steel, they can be made of any other material suitable for the intended application.

[0074] The number of actuators 41 may be different from that described and illustrated.

[0075] Although the actuators 41 are here carried by the same actuator-carrying ring 40, they can also be carried directly by the torque tube 30.

[0076] Although the actuators 41 are hydraulic here, they can also be electric, pneumatic, etc.

[0077] The pistons 41.1 of the actuators 41 can be replaced by any other equivalent means capable of performing this function.

[0078] The helical springs 13 can be replaced by any elastic return means allowing the stator 11 to be returned to the free rotation position (gas springs, Belleville type washers, etc.).

[0079] The invention can be used on any type of vehicle, air, land or amphibious.

[0080] The invention can be used for applications other than a vehicle and for example for any equipment, industrial or personal, requiring braking.

Claims

CLAIMS 1. Braked vehicle wheel (1) mounted for rotation on an axle (E) around an axis (X), comprising: - a first magnetic braking device (10), comprising a stator (11) and a rotor (12) arranged to produce between them a magnetic flux capable of generating eddy currents producing a first braking torque of the wheel, one of the stator and the rotor being arranged to move along the axis (X) of rotation of the wheel between a position of free rotation of the wheel and a braking position of the wheel and to be returned to the position of free rotation by elastic return means; - a second braking device (20), by friction, comprising a stack of discs comprising at least one stator disc (21.1, 21.2, 21.3) and one rotor disc (22.1, 22.2) arranged to rub against each other, producing a second braking torque for the wheel, the stack of discs comprising a rear face axially facing the stator or the rotor arranged to move along the axis of rotation of the wheel; and - at least one actuator (41) arranged to exert on a front face of the stack of disks a pressing force sufficient to force the stator disk and the rotor disk to rub against each other and cause the stator or the rotor to move from the free rotation position to the braking position.

2. Wheel (1) according to claim 1, in which the first braking device (10) is radial flow.

3. Wheel (1) according to any one of the preceding claims, comprising an annular rim (2) connected by a web (3) to a hub (4) pivotally received on the axle (E), the rim delimiting with the web and the hub an annular space in which the first braking device (10) and the second braking device extend. (20) .

4. Wheel (1) according to any one of the preceding claims, in which the elastic return means comprise at least one spring (13).

5. Wheel (1) according to any one of the preceding claims, in which the stator disc (21.1, 21.2, 21.3) and the rotor disc (22.1, 22.2) are slidably mounted along the axis (X) of rotation of the wheel on a torsion tube (30) fixed to the axle (E).

6. Wheel (1) according to claim 5, in which the stator (11) is slidably mounted along the axis (X) of rotation of the wheel on the torsion tube (30).

7. Wheel (1) according to any one of the preceding claims, in which the stator (11) carries magnets (11.3).

8. Wheel (1) according to any one of the preceding claims, wherein the actuator (41) is a hydraulic actuator.

9. Landing gear (P) of an aircraft (A) comprising at least one wheel (1) according to any one of the preceding claims.

10. Aircraft (A) comprising at least one landing gear (P) according to claim 9.

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