CHASSIS OF AN AERIAL VEHICLE EQUIPPED WITH AT LEAST ONE MOTORIZED WHEEL

Description

[0001] The present invention relates to the field of aircraft landing gear equipped with at least one motorized wheel and at least one braked wheel. BACKGROUND OF THE INVENTION

[0002] The patent document FR3072943A1 describes a landing gear with an upper part intended to be assembled with an aircraft structure and a lower part equipped with a bogie forming a rocker arm and two axles carried at the ends of this bogie.

[0003] This landing gear has a leg connecting the upper and lower parts. The two axles of the landing gear are perpendicular to the bogie.

[0004] The front axle is equipped with a plurality of braked wheels, and the rear axle is equipped with at least one powered wheel to allow the aircraft to maneuver on the ground (taxiing). Each powered wheel is thus arranged to transmit maneuvering forces to the ground, and each braked wheel is arranged to transmit braking forces to the ground.

[0005] A damper actuator is connected to the bogie on one side and to the landing gear leg on the other to orient the bogie in a pitching motion, thus simultaneously moving the braked and driven wheels. The distribution of forces between the braked wheels at the front and the driven wheels at the rear is difficult to control with this single damper actuator coupled to the bogie, and each driven wheel is susceptible to accelerations causing significant shocks during takeoff and landing, necessitating substantial safety margins in its design. A landing gear is also described in document US2016 / 009620A1. SUBJECT OF THE INVENTION

[0006] One object of the present invention is to provide a landing gear that limits the risk of damage to the motorized wheel during takeoff or landing phases. SUMMARY OF THE INVENTION

[0007] To this end, the invention relates to an aircraft landing gear having an upper part intended to be assembled to an aircraft structure and a lower part equipped with first and second axles, the first axle being equipped with at least one braked wheel and the second axle being equipped with at least one motorized wheel.

[0008] The lander according to this first aspect of the invention is detailed in claim 1.

[0009] Thanks to the invention, during all phases of the aircraft's rolling on the rolling surface, it is certain that the aircraft is at least supported by the braked wheel(s) equipping the first axle, while each motorized wheel equipping the second axle can be selectively moved relative to the rolling surface by the first actuator.

[0010] As long as the taxiing conditions do not allow the motorized wheel to make contact with the rolling surface (for example because the aircraft is moving at high speed), a gap can be maintained between the motorized wheel and the rolling surface, only a braked wheel being able to make contact with the rolling surface.

[0011] When driving conditions permit, it may be decided to activate the first actuator to bring each motorized wheel equipping the second axle into contact with the rolling surface in addition to each braked wheel equipping the first axle.

[0012] For understanding the invention: a braked wheel is a wheel mechanically coupled with a brake to apply a torque opposing the rotation of this braked wheel relative to the axle equipped with this braked wheel (in this case the first axle); and a motorized wheel is a wheel mechanically coupled to a motor intended to selectively apply a motor torque causing the rotation of this motorized wheel relative to the axle equipped with this motorized wheel (in this case the second axle).

[0013] During the landing, takeoff or high-speed taxiing phases, each motorized wheel of the lander according to the invention can be kept away from the rolling plane.

[0014] Thus, thanks to the invention, it is possible to prevent the motorized wheel from being subjected to an impact against the rolling surface at the time of landing or from being subjected to too high a rotational speed during taxiing.

[0015] The motorized wheel can thus be protected against high-intensity accelerations or impacts.

[0016] The invention also makes it possible to dispense with a means of disengaging the motorized wheel from the engine since it is possible to choose the aircraft speed conditions required to bring the motorized wheel into contact with the ground.

[0017] The size of the motorized wheel can be adapted to the sole need to maneuver the aircraft (towing or pushing the aircraft).

[0018] The motorized wheel / tire assembly and the entire drivetrain between this wheel and the motor is subjected to much lower speeds and forces than braked wheels, which helps to reduce the risk of damage to the motorized wheel.

[0019] The ability to move the motorized wheel away from the rolling surface during braking phases prevents degradation of braking performance.

[0020] It is also conceivable that the movement of at least one wheel driven by the first actuator could be synchronized with the aircraft's speed with a less precise accuracy than that normally required to manage a wheel drive clutch with its motor. The transmission error could be compensated for by the flexibility and slippage of the tire on each wheel.

[0021] Another advantage of the landing gear according to the invention is that it can be optionally installed on an existing aircraft landing gear by adding a motorized wheel and a first actuator allowing it to be moved relative to the upper part of the landing gear without moving the braked wheel.

[0022] According to a preferred embodiment, the first actuator is arranged to move the second axle between the distant position and the close position with respect to said upper part independently of the first axle.

[0023] The first axle is equipped with at least one braked wheel and is not equipped with any motorized wheel (any wheel equipping the first axle is a braked wheel).

[0024] The second axle is equipped with at least one motorized wheel and is not equipped with any braked wheel (Any wheel equipping the second axle is a motorized wheel).

[0025] The invention also relates to an aircraft comprising at least one landing gear according to any one of the landing gear embodiments of the invention. This aircraft is arranged to selectively adopt first and second aircraft configurations distinct from each other.

[0026] In the first aircraft configuration, at least one braked wheel equipping the first axle and at least one motorized wheel equipping the second axle are simultaneously in contact against a rolling surface to allow the aircraft to taxi.

[0027] In the second aircraft configuration, said at least one braked wheel equipping the first axle is in contact against a rolling surface while said at least one motorized wheel equipping said second axle is away from this rolling surface, the passage from one of these aircraft configurations to the other of these aircraft configurations being done by actuation of said first actuator.

[0028] Such an aircraft benefits from the advantages associated with the lander according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Other features and advantages of the invention will become clear from the description given below, by way of example and not limitation, with reference to the accompanying drawings, in which: there figure 1a is a side view of a part of aircraft 2 according to the invention, this aircraft comprising an aircraft structure area 2a (illustrated in dashed lines on this single figure 1a ) and a landing gear 1 according to the invention, an upper part 1a of which is movably assembled onto this structural area 2a; the landing gear 1 is here in a landing configuration where each braked wheel is in contact with the ground's running surface P and where each motorized wheel 4a is brought closer to the upper part 1a to remain away from the running surface P; the aircraft is here in the landing phase, known as "LANDING"; the figure 1b is a side view of the landing gear 1 according to the invention while it is in a taxiing configuration where each of the motorized wheel(s) 4a and braked wheel(s) 3a is in contact on the rolling surface P; the aircraft is here in the taxiing phase, known as the "TAXI" phase; the figure 1c is a side view of the landing gear 1 according to the invention, which is in takeoff configuration where each powered wheel 4a is away from the running surface P, while each braked wheel is in contact with the surface P to support the aircraft; the aircraft is here in the takeoff phase, known as the "TAKE-OFF" phase; the figure 2a is a side view of the lander 1 according to the invention, associated with a longitudinal section of the first actuator 5 while the lander is in landing configuration where only the braked wheels 3a are in contact with the running surface P while each powered wheel 4a is away from this surface P; the figure 2b is a side view of the landing gear 1 according to the invention, associated with a longitudinal section of the first actuator 5 while the landing gear 1 is in a taxiing configuration (within a speed range compatible with the use of a powered wheel to maneuver the aircraft), in this configuration each powered wheel 4a and each braked wheel 3a is in contact against the rolling surface P and the damper 51 of the first actuator 5 is extended, slightly compressed, the landing gear being under minimum static load; the figure 2c is a side view of the landing gear 1 according to the invention, associated with a longitudinal section of the first actuator 5 while the landing gear 1 is in taxiing configuration (within a speed range compatible with the use of powered wheels to maneuver the aircraft). In this configuration, each powered wheel 4a and each braked wheel 3a is in contact with the running surface P. The damper 51 of the first actuator 5 is more strongly compressed here, because the landing gear is under maximum static load; the figure 3 is a front view of a portion of the landing gear according to the invention illustrating a first method of connection between a driven wheel 4a and the second axle 4, in which the driven wheel 4a is connected to the motor M which drives it via a transmission shock absorber A (this type of tangential spring shock absorber filters certain variations in the transmission torque between the motor and the driven wheel 4a) and via a speed reducer R transmitting the torque from the motor M to the wheel 4a so as to drive it to rotation at a speed lower than the rotational speed of the motor M; the figure 4 is a front view of a portion of the lander according to the invention illustrating a second mode of connection between a motorized wheel 4a and the second axle 4, in which the motorized wheel 4a and the motor are integrated to form a wheel motor, here the motor belonging to a propulsion system assembly M1 which is included in the wheel 4a; the figure 5a is a side view of a part of aircraft 2 according to an example which is not within the scope of the claims, this aircraft 2 comprising an aircraft structure area 2a (illustrated in dashed lines on this single figure 5a ) and a landing gear 1 according to the second embodiment of the invention, an upper part 1a of which is movably assembled on this structural area 2a; the landing gear 1 is here in the landing configuration where each braked wheel is in contact with the ground contact plane P and where each motorized wheel 4a is brought closer to the upper part 1a to remain away from the ground contact plane P; the aircraft is here in the landing phase, known as "LANDING"; the figure 5b is a side view of the landing gear 1 according to an example which is not within the scope of the claims, while it is in its taxiing configuration where each of the powered wheel(s) 4a and braked wheel(s) 3a is in contact on the running surface P, the aircraft is here in the taxiing phase, known as the "TAXI" phase; the figure 5c is a side view of the landing gear 1 according to an example which is not within the scope of the claims, this landing gear being in takeoff configuration where each powered wheel 4a is away from the running plane P while each braked wheel 3a is in contact against the plane P to support the aircraft, the aircraft is here in takeoff phase, known as the "TAKE-OFF" phase. DETAILED DESCRIPTION OF THE INVENTION

[0030] The lander according to the invention is illustrated by the figures 1a, 1b, 1c , 2a , 2b , 2C which show different configurations adopted by lander 1 during its use.

[0031] This aircraft 2 landing gear 1 has an upper part 1a intended to be assembled to a structure 2a of aircraft 2.

[0032] A lower part 1b of the lander 1 is equipped with first and second axles 3, 4.

[0033] The first axle 3 is here a rear axle and the second axle 4 is here a front axle with respect to a usual direction S of movement of the aircraft 2. This arrangement is advantageous because it allows better control of the load applied to the motorized wheel 4a.

[0034] The first axle 3 is equipped with braked wheels 3a.

[0035] The second axle 4 is equipped with a motorized wheel 4a.

[0036] These first and second axles 3, 4 are parallel to each other so that each wheel 3a equipping the first axle can rotate around a main axis of the first axle 3 and that each wheel 4a equipping the second axle 4 can rotate around a main axis of the second axle, these main axes of the first and second axles 3, 4 are parallel to each other.

[0037] Each braked wheel 3a can roll on the rolling plane P and thus, on the one hand, support part of the weight of the aircraft 2 during landing, during taxiing of the aircraft and during takeoff and, on the other hand, transmit a braking force of the aircraft when a brake associated with a braked wheel is activated.

[0038] Each motorized wheel allows rolling on the rolling plane P and allows the transmission of a maneuvering force of the aircraft (force causing the movement of the aircraft) when the motorized wheel is brought into contact with the plane P and the motor associated with this motorized wheel 4a is activated.

[0039] The lander 2 includes a first actuator 5 arranged to move the second axle 4 between a distant position and a close position with respect to said upper part 1a independently of the first axle 3.

[0040] In the extended position, the wheels 3a, 4a which equip the first and second axles 3, 4 are positioned to be simultaneously in contact against the rolling surface P.

[0041] In the close position each wheel 3a equipping the first axle 3 is positioned so that it can be in contact with the rolling plane P while each wheel 4a equipping the second axle 4 is positioned to remain at a distance from this plane P.

[0042] As illustrated on the figures 1a à 2c , the landing gear 1 according to the invention is preferably a main landing gear of the aircraft.

[0043] Such a lander adopts a retracted configuration in which it is placed in an area of ​​the structure 2a of aircraft 2 and a deployed configuration in which it extends under aircraft 2 in order to support it and allow it to taxi on the taxiway P.

[0044] The lander is here connected to structure 2a via a main pivot axis XX of the lander substantially parallel to the usual direction of movement S of the aircraft.

[0045] Alternatively, the landing gear according to the invention could be connected to the structure 2a of the aircraft 2 via any other conventionally used connection mechanism.

[0046] The lander also includes a main actuator (not shown) to control the passage of the lander (here by pivoting the lander around the XX axis) between its retracted and deployed configurations.

[0047] Each wheel 3a equipping the first axle 3 is a braked wheel 3a and each wheel 4a equipping the second axle 4 is a motorized wheel 4a.

[0048] The lander has a leg 10, the upper end of which belongs to the upper part 1a of the lander 1 and the lower end of which belongs to the lower part 1b of the lander.

[0049] A control arm 40 is mounted pivotally opposite this leg 10, in this case via a pivot 41 located at the lower end of the leg 10.

[0050] The second axle 4 equipped with the motorized wheel 4a is fixed on this maneuvering arm 40 at a distance from the leg 10.

[0051] The first actuator 5 is connected on the one hand to the leg 10 and on the other hand to said operating arm 40 to pivot this operating arm 40 relative to the leg 10 and thus move the second axle between its distant position with respect to the upper part 1a and its close position with respect to the upper part 1a.

[0052] The lander also includes a main arm 30 which is pivotally mounted opposite the leg 10 via a pivot 41 located at the lower end of the leg 10.

[0053] This pivot 41 may be the same as that used for the pivoting mounting of the operating arm 40 vis-à-vis the leg 10 but it could be another pivot.

[0054] The control arm 40 is mounted pivotally opposite the leg 10 to allow only a pitching movement of this control arm 40.

[0055] Similarly, the main arm 30 is mounted pivotally with respect to the leg 10 to allow only a pitching movement of this main arm 30.

[0056] A pitching motion is a rotational motion around a transverse axis of the landing gear which, during taxiing, is parallel to the transverse axis of the aircraft 2.

[0057] The first axle 3 is fixed on the main arm 30, at a distance from the leg 10.

[0058] A main shock absorber 6 is connected on the one hand (via a first pivot link) to the leg 10 and on the other hand connected (via a second pivot link) to said main arm 30 to dampen a pivoting movement of this main arm 30 relative to the leg 10 and thus dampen displacements of the first axle 3 with respect to the leg 10.

[0059] Thus, the movement of the first axle 3 is damped by the main shock absorber 6, which allows the leg 10 to belong to a damped suspended part of the lander and the motorized wheel 4a and the first actuator 5 to be assembled on this suspended part of the lander.

[0060] The equipment which is fixed on the suspended part is thus protected from vibrations caused during the rolling of the braked wheels 3a.

[0061] Preferably, the first axle 3 is equipped with at least two braked wheels 3a.

[0062] Preferably these braked wheels 3a are arranged on either side of the main arm 30.

[0063] To simplify the side views of the lander according to the invention illustrated in figures 1a, 1b, 1c , 2a , 2b , 2cThe braked wheel, which normally conceals the main arm 30, has been omitted. It should be noted that the number of braked wheels 3a and their arrangement on the first axle 3 could vary without departing from the scope of the present invention.

[0064] Here, the second axle 4 extends mainly from one side of the maneuvering arm 40 where the single powered wheel 4a of the lander is located.

[0065] However, it is conceivable that this second axle 4 could be equipped with several motorized wheels, the number and arrangement of which could vary without departing from the scope of the invention.

[0066] In particular, we could have two motorized wheels respectively placed on either side of the maneuvering arm 40.

[0067] It should be noted that in general each motorized wheel 4a is associated with a corresponding motor M which enables its drive, but it is also possible that a motorized wheel may be driven by several motors or conversely that the same motor drives several motorized wheels.

[0068] Preferably the drive motor of a motorized wheel 4a is an electric motor M powered by an electrical power supply unit belonging to the aircraft.

[0069] As illustrated on the figure 3 , a motor M can be mounted outside the motorized wheel 4a with a kinematic chain between the motor M and the wheel 4a which is fully supported by the second axle 4, the motor M being located at a distance from the wheel 4a, between the operating arm 40 and the wheel 4a.

[0070] Alternatively, as illustrated on the figure 4 The motor can be integrated into the wheel. In this mode, the motor belongs to a propulsion system assembly M1 essentially located in the wheel 4a, at a distance from the tire 4a1.

[0071] Preferably, the first actuator 5 includes a first damper 51 interposed between the operating arm 40 and the leg 10 so as to dampen a pivoting movement of the operating arm 40 relative to the leg 10.

[0072] As we understand from the figures 2a à 2c , this first shock absorber 51 has first and second parts 511, 512 mounted sliding relative to each other and together defining first and second shock absorber chambers 513, 514 which are separated from each other by a movable wall 515 of the first shock absorber 51.

[0073] This movable wall 515 is defined here by a portion of the first sliding part 511 which forms a sealed sliding piston in a cylinder 512a defined in the second part 512.

[0074] These first and second chambers 513, 514 of the first damper 51 have respective internal volumes which vary according to a sliding position of the movable wall 515 of the damper vis-à-vis the second sliding part 512 of the first damper 51.

[0075] Alternatively, the movable wall 515 which delimits the two chambers 513, 514 could be defined by a portion of the second sliding part 512 which would form a sealed sliding piston in a cylinder defined in the first part 511.

[0076] The movable wall 515 is equipped with at least one passage connecting chambers 513, 514 to each other to allow fluid to pass from one of these chambers to the other of these chambers in order to dampen the movement of the first and second parts 511, 512 relative to each other)

[0077] The first actuator 5 also includes a telescopic cylinder 52 of variable length to vary the orientation of the operating arm 40 relative to the leg 10.

[0078] The telescopic cylinder 52 of the first actuator is a hydraulic cylinder with a first port 521 for passing hydraulic fluid.

[0079] The length of this cylinder 52 is variable depending on the volume of hydraulic fluid admitted into this cylinder 52 via this first hydraulic fluid passage port 521.

[0080] The telescopic cylinder 52 of the first actuator 5 comprises a first cylinder rod 52a and a first cylinder 52b.

[0081] The first cylinder rod 52a is mounted sliding with a seal in this first cylinder 52b so as to define a main chamber 523 into which said first passage port 521 of hydraulic fluid opens.

[0082] The first cylinder rod 52a and the first cylinder 52b together define a secondary chamber 524 into which a second hydraulic fluid passage port 522 opens.

[0083] This 52 telescopic hydraulic cylinder is a double-acting cylinder with variable length between a minimum and a maximum length.

[0084] Its minimum length is reached when the first cylinder rod 52 is against a first stop formed inside the main chamber 523.

[0085] Its maximum length is reached when the first cylinder rod is against a second stop formed inside the secondary chamber 524.

[0086] The increase in length of this cylinder 52 is achieved by admitting fluid into the main chamber 523 via the first port 521 and by expelling fluid out of the secondary chamber 524 via the second port 522.

[0087] The reduction in length of this cylinder 52 is done by admitting fluid to the secondary chamber 524 via the second port 522 and by expelling fluid from the main chamber 523 via the first port 521.

[0088] Aircraft 2 includes a hydraulic circuit (not shown) with a high-pressure hydraulic fluid supply line connected to a hydraulic pump and a low-pressure fluid return line relative to said high pressure.

[0089] Aircraft 2 also includes a hydraulic distribution system (not shown) connected to the first and second ports of cylinders 521 and 522 and to the supply and return lines to selectively adopt: at least one cylinder length extension configuration 52 in which the first port 521 is connected to the supply line and the second port 522 is either preferentially connected to the return line or connected to the first port 521; and at least one cylinder length reduction configuration in which the second port is connected to the supply line and the first port is connected to the return line.

[0090] According to a particular mode, it could be foreseen that the hydraulic distribution system could adopt a cylinder immobilization configuration in which the circulation of fluid via the first and second ports 521, 522 would be prohibited.

[0091] This cylinder 52 could also be a monostable cylinder which, in the event of a hydraulic supply failure, for example in the event of a drop in hydraulic pressure in at least one of its chambers below a predefined minimum value, would automatically return to an actuator length 52 in which the driven wheel 4a is away from the running plane P. For this purpose, the actuator of the figures 2a , 2b , 2c could be equipped with an elastic return means (not illustrated) exerting an elastic force opposing the extension of cylinder 52.

[0092] The first actuator 5 also includes a locking system 53 selectively adopting a locked configuration and an unlocked configuration.

[0093] In its locked configuration, the telescopic cylinder 52 of the first actuator 5 is locked to maintain the second axle 4 in its close position vis-à-vis said upper part 1a of the lander.

[0094] In its unlocked configuration, the telescopic cylinder 52 is released to be able to move the second axle 4 between its position close to the upper part 1a of the lander and its position far from said upper part 1a of the lander.

[0095] This locking system 53 is arranged to switch from its locked configuration to its unlocked configuration in response to an unlock command.

[0096] In this case, the unlocking command consists of an increase in hydraulic fluid pressure admitted through the first hydraulic fluid passage port.

[0097] As will be understood later, the switch from the unlocked configuration to the locked configuration happens automatically when the telescopic cylinder 52 is retracted.

[0098] As illustrated on the figures 2a , 2b , 2c, the locking system 53 includes claws 531 and a sliding ring 532 relative to a body 520 of the telescopic cylinder 52 between a locking position of the claws 531 and a release position of the claws 531.

[0099] This locking system 53 is arranged so that when it is in the locked configuration (see the figure 2a ), the sliding ring 532 is then in its claw locking position 531 where it jams end portions of the claws 531 in a receiving area of ​​these claw ends so that the jammed claws oppose any variation in length of the telescopic cylinder 52.

[0100] This locking system 53 is also arranged in such a way that when it is in the unlocked configuration (see the figures 2b And 2c), the sliding ring 532 is then in its claw release position 531 and the end portions of the claws 531 are then free to move away from said claw end reception area so as to allow a variation in length of the telescopic cylinder 52.

[0101] The sliding ring 532 of the locking system 53 is arranged here so as to move from its claw locking position 531 to its claw release position under the effect of an increase in hydraulic fluid pressure inside the main chamber 53 beyond a predetermined minimum pressure threshold.

[0102] The first rod 52a of the cylinder 52 carries an elastically deformable stop 534 intended to come against the sliding ring 532 of the locking system 53 when the telescopic cylinder 52 is retracted and has a running length less than a predetermined length value from which the elastically deformable stop 534 is brought into contact with the ring 532.

[0103] Here the elastically deformable stop 534 is made up of a washer 5341 mounted sliding around an end area of ​​the first rod of the cylinder 52 and of a spring 5342 also mounted around this end area of ​​the first rod.

[0104] This spring 5342 pushes this washer 5341 towards the sliding ring 532.

[0105] The first rod 52a has a terminal protrusion against which the washer 5341 butts under the effect of the spring 5342 as long as this washer 5341 is kept away from the sliding ring 532 of the locking system.

[0106] Thus, when the cylinder retracts, and the rod 512 of the cylinder 52 approaches the end of the stroke, the claws 531 first come into contact in the receiving area of ​​these claw ends which is here partly formed by an annular groove in the rod 512 then, secondly, the elastically deformable stop 534 carried by the rod of the cylinder 512 comes into contact with the ring 532 and pushes the ring 532 towards its claw locking position.

[0107] The ends of the claws 531 are then blocked in the claw reception area, the ring 532 then butts against these ends of the claws to prevent them from exiting the claw reception area.

[0108] When the hydraulic pressure in chamber 523 passes the predetermined threshold, the sealing sliding ring 532 is moved to its release position from the claws 531 and moves away from the claws which can then move freely out of the claw receiving area so as to allow the rod 512 to slide and the cylinder 52 to expand.

[0109] Thanks to these claws 531, each motorized wheel 4a carried by the second axle is secured away from the running surface and only a voluntary action of increasing the pressure in the chamber 523 makes it possible to release the claws and allow the movement of the operating arm 40 by the first actuator 5 in order to force the motorized wheel against the running surface.

[0110] The damper 51 of the first actuator 5 is shaped to exert a restoring force forcing this damper to return to an extended configuration of the damper 51.

[0111] This first actuator 5 is arranged so that when the driven wheel is in contact with the rolling surface, the damper 51 is compressed and exerts an elastic force opposing this compression. Thus, the driven wheel 4a is forced towards the ground P, which improves the wheel's friction on the ground and increases the transmissible driving force of the driven wheel 4a.

[0112] The aircraft may also include a landing gear control unit which is connected to said hydraulic distribution system.

[0113] The first actuator 5 is preferably controlled via a control unit (not shown) so that as long as the speed of the aircraft 2 is above a predetermined speed threshold, this first actuator 5 applies a force tending to maintain the second axle 4 in its close position vis-à-vis said upper part 1a of the landing gear 1.

[0114] Thus, as long as the speed of the aircraft is above the predetermined speed threshold, the motorized wheels 4a are necessarily away from the rolling plane P (ground) and only the braked wheel(s) 3a carried by the first axle 3 can come into contact with the rolling plane P.

[0115] The first actuator 5 is preferentially controlled by the control unit so that when the speed of the aircraft is below the predetermined speed threshold, this first actuator 5 then applies a force tending to maintain the second axle 4 exclusively equipped with motorized wheel in its distant position with respect to said upper part 1a of the landing gear 1 (each motorized wheel carried by this second axle 4 then being in contact against the running plane P and each braked wheel carried by the first axle 3 also being in contact with the running plane).

[0116] It should be noted that the main shock absorber 6 could also include controllable adjustment means to vary its length, stiffness, and / or damping. Thus, the variation in length, stiffness, and / or damping of the main shock absorber could vary according to the aircraft's speed.

[0117] Thus, as long as the speed of the aircraft is above the predetermined speed threshold, this main damper 6 could be controlled to apply on the main arm 30 a force tending to press the braked wheel 3a against the running plane P and to keep the leg 10 at a sufficient distance from the running plane P to ensure that no powered wheel 4a carried by the second axle 4 can come into contact with the running plane P.

[0118] On the other hand, as long as the speed of the aircraft 2 is below the predetermined speed threshold and the second axle 4 is in its distant position with respect to the upper part 1a, this main shock absorber 6 and the first actuator 5 could be controlled to press the motorized and braked wheels onto the rolling plane P and thus regulate the distribution of the aircraft's support forces between the braked and motorized wheels.

[0119] In this way we can guarantee that at every moment during the rolling of the motorized and braked wheels, each motorized wheel can transmit effective traction forces from the aircraft and that each braked wheel can support the aircraft while transmitting effective braking forces.

[0120] The control of the first actuator 5, allows to optimize the ground contact force applied by the motorized wheel during rolling and it therefore allows to optimize the distribution of forces between motorized wheel(s) and braked wheel(s).

[0121] In general, thanks to the invention, during rolling, each braked wheel 3 equipping the first axle remains in contact against the rolling plane while said at least one motorized wheel equipping the second axle is selectively brought into contact against the rolling plane P or moved away from this rolling plane P depending on whether the current rolling speed is adapted or not to the operation of the motorized wheel.

[0122] Thanks to the invention: The tire of each braked wheel and the diameter of each braked wheel can be adapted to meet the needs associated with the landing, braking, and takeoff phases; whereas the tire of each motorized wheel and the diameter of each motorized wheel can be adapted to meet only the maneuvering needs of the aircraft, during taxiing ranges outside of the landing, high-power braking, and takeoff phases.

[0123] The invention is not limited to the examples described above and encompasses any variant falling within the scope defined by the claims.

[0124] In the embodiment of the aircraft 2 landing gear 1 illustrated in figures 5a, 5b, 5c , this mode not being within the scope of the claims, the landing gear 1 always has an upper part 1a intended to be assembled to a structure 2a of the aircraft 2 and a lower part 1b equipped with first and second axles 3, 4. The first axle 3 is always equipped with at least one braked wheel 3a and the second axle 4 is always equipped with at least one motorized wheel 4a.

[0125] The lander 1 always includes a first actuator 5 arranged to move the second axle 4 between a distant position and a close position relative to the upper part 1a independently of the first axle 3 in such a way that: in one of the said positions, illustrated in the figure 5b , the wheels 3a, 4a can be simultaneously in contact against a rolling plane P while; in the other of said positions, illustrated by the figures 5a ou 5b , each wheel 3a equipping the first axle 3 is in contact against the rolling plane P while each wheel 4a equipping the second axle 4 remains at a distance from this rolling plane P.

[0126] The lander of figures 5a, 5b, 5c includes a leg 10 formed of a lower part 10a carrying the first axle 3 and an upper part 10b intended to be connected to the structure 2a of the aircraft.

[0127] The upper part 10b of the leg 10 belongs to the upper part 1a of the lander 1 and the lower part 10a of the leg belongs to the lower part 1b of the lander.

[0128] These lower and upper parts 10a, 10b of the leg 10 slide relative to each other along a longitudinal axis ZZ of the leg 10 and a main damper 6 is arranged to dampen the relative sliding of the lower part 10a of the leg 10 vis-à-vis the upper part 10b.

[0129] The upper part 10b of the leg includes a landing gear box and the lower part 10a includes a sliding rod carrying the first axle 3, this rod sliding inside the box.

[0130] A maneuvering arm 40 carrying the second axle 4 is mounted for rotation on the upper part 10b of the leg 10, the first actuator 5 controlling the orientation of this maneuvering arm 40 vis-à-vis the leg 10.

[0131] The control arm 40 is mounted pivotally opposite the leg 10 to allow only a pitching movement of this control arm 40.

[0132] The first actuator 5 is always connected on one side to the leg 10 and on the other side to said operating arm 40 to pivot this operating arm 40 relative to the leg 10 and thus move the second axle 4 between its distant position vis-à-vis the upper part 1a and its close position vis-à-vis the upper part 1a.

[0133] This first actuator 5 is identical here to the one illustrated in figures 1a à 2c .

[0134] In this variant of figures 5a à 5c , which is not within the scope of the claims, the second axle 4 and the motorized wheel(s) 4a are carried by the operating arm 40 in accordance with what has been presented previously with reference to the figures 1a à 4 .

[0135] However, unlike the implementation method illustrated on the figures 1a à 4 where the first axle 3 is supported by the main arm 30, on the figures 5a, 5b, 5c In an example not within the scope of the claims, the first axle 3 is directly assembled on the lower part 10 of the leg 10, in this case on the sliding rod.

[0136] Finally, in this method of implementation of the figures 5a à 5cA compass is used to allow the lower part 10a to slide relative to the upper part 10b. This compass 11 has upper arms 11b and lower arms 11a articulated relative to each other.

[0137] The upper arm 11b is pivotally mounted on the upper part 10b via an upper axis and the lower arm 11a is pivotally mounted on the lower part 10a via a lower axis, these upper and lower axes being parallel to each other.

[0138] The invention may include other embodiments, in particular, although the locking system 53 presented above includes claws, it could alternatively include translationally movable locking segments to alternatively lock the actuator and prohibit the movement of the second axle 4 relative to the upper part 1a of the landing gear or unlock the actuator and allow the movement of the second axle 4 relative to the upper part 1a.

[0139] To this end, the locking system may include segments mounted to slide transversely relative to the body of the telescopic cylinder 52 and a movable part relative to this body 520 of the cylinder between a locking position of the segments and a releasing position of the segments.

[0140] The locking system 53 is arranged here in such a way that: when in the locked configuration, the moving part is then in its segment locking position where it pushes end portions of the segments into a receiving area for these segment ends so that the segments thus pushed oppose any variation in length of the telescopic cylinder 52; and so that when in the unlocked configuration, the moving part relative to the body 520 of cylinder 52 is then in its segment release position and the end portions of the segments are free to move away from said receiving area for the segment ends so as to permit a variation in length of the telescopic cylinder 52.

Claims

1. Landing gear (1) for an aircraft (2) having an upper portion (1a) intended to be joined to a structure (2a) of the aircraft (2) and a lower portion (1b) provided with a first and a second axle (3, 4), the first axle (3) being provided with at least one braked wheel (3a) and the second axle (4) being provided with at least one motorised wheel (4a), the landing gear (1) comprises a first actuator (5) arranged to move one of the axles (4) between remote and close positions with respect to the upper portion (1a) independently from the other of the axles (3) such that, in one of said positions, the wheels (3a, 4a) can be simultaneously in contact with a running surface (P) while in the other of said positions, each wheel (3a) on the first axle (3) is in contact with the running surface (P) while each wheel (4a) on the second axle (4) remains at a distance from this running surface (P), the landing gear comprising a strut (10) having an upper end belonging to the upper portion (1a) of the landing gear (1) and a lower end belonging to the lower portion (1b) of the landing gear and an operating arm (40), this operating arm (40) being pivotably mounted with respect to the strut (10), said second axle (4) provided with the motorised wheel (4a) being fixed on this operating arm (40) at a distance from the strut (10), the first actuator (5) being, on the one hand, connected to the strut (10) and, on the other hand, connected to said operating arm (40) to pivot this operating arm (40) with respect to the strut (10) and thus move the second axle between its remote position with respect to the upper portion (1a) and its close position with respect to the upper portion (1a), characterised in that the first actuator (5) comprises a first damper (51) interposed between the operating arm (40) and to the strut (10) so as to dampen a pivot movement of the operating arm (40) with respect to the strut (10), the aircraft landing gear further comprising a main arm (30) pivotably mounted with respect to the strut (10), said first axle (3) provided with the braked wheel (3a) being fixed to this main arm (30) at a distance from the strut (10), a main damper (6) being, on the one hand, connected to the strut (10) and, on the other hand, connected to said main arm (30) to dampen a pivot movement of this main arm (30) with respect to the strut (10) and thus dampen movements of the first axle (3) with respect to the strut (10).

2. Aircraft landing gear according to claim 1, wherein the first actuator (5) comprises a telescopic jack (52) of variable length to make the orientation of the operating arm (40) vary with respect to the strut (10).

3. Aircraft landing gear according to claim 2, wherein the first actuator (5) comprises a locking system (53) selectively adopting a locked configuration and an unlocked configuration, in its locked configuration, the telescopic jack (52) of the first actuator (5) is blocked to keep the second axle (4) in its close position with respect to said upper portion (1a) of the landing gear and in its unlocked configuration, the telescopic jack (52) being released to be able to move the second axle (4) between its close position with respect to the upper portion (1a) of the landing gear and its remote position with respect to said upper portion (1a) of the landing gear.

4. Aircraft landing gear according to claim 3, wherein the locking system (53) is arranged to pass from its locked configuration to its unlocked configuration in response to an unlocking control.

5. Aircraft landing gear according to any one of claims 3 or 4, wherein the locking system (53) comprises claws (531) and a sliding ring (532) with respect to a body (520) of the telescopic jack (52) between a position for blocking the claws (531) and a position for releasing the claws (531), the locking system (53) being arranged such that: when it is in the locked configuration, the sliding ring (532) is thus in its position for blocking the claws (531) where it catches the end portions of the claws (531) in a zone for receiving these ends of claws such that the claws thus caught oppose any variation in length of the telescopic jack (52); and such that when it is in the unlocked configuration, the sliding ring (532) is thus in its position for releasing the claws (531) and the end portions of the claws (531) being free to be distanced from said zone for receiving the ends of claws so as to enable a variation in length of the telescopic jack (52).

6. Aircraft landing gear according to any one of claims 3 or 4, wherein the locking system (53) comprises segments slidingly mounted transversally with respect to the body of the actuator (520) and a movable part with respect to the body (520) of the telescopic jack (52) between a position for blocking the segments and a position for releasing the segments, the locking system (53) being arranged such that: when it is in the locked configuration, the movable part is thus in its position for blocking the segments where it pushes end portions of the segments in a zone for receiving these segment ends, such that the segments thus pushed oppose any variation in length of the telescopic jack (52); and such that when it is in the unlocked configuration, the movable part with respect to the body is thus in its position for releasing segments and the end portions of the segments being free to be distanced from said zone for receiving segment ends so as to enable a variation in length of the telescopic jack (52).

7. Aircraft landing gear according to any one of claims 2 to 6, wherein the telescopic jack (52) of the first actuator is a hydraulic cylinder provided with a first port (521) for the passage of hydraulic fluid, the length of this jack (52) being variable according to a volume of hydraulic fluid taken into this actuator (52) via this first port (521) for the passage of hydraulic fluid.

8. Aircraft landing gear according to claim 7, wherein the telescopic jack (52) of the first actuator (5) comprises a first jack rod (52a) and a first cylinder (52b), the first jack rod (52a) being sealingly slidingly mounted in this first cylinder (52b) so as to define a main chamber (523) in which said first port for the passage (521) of hydraulic fluid leads.

9. Aircraft landing gear according to claim 8, wherein the first jack rod (52a) and the first cylinder (52b) together define a secondary chamber (524) in which a second port for the passage (522) of hydraulic fluid leads, this telescopic hydraulic jack (52) of the first actuator (5) being a double-acting cylinder of variable length between a minimum length and a maximum length.

10. Landing gear according to any one of claims 1 to 9, wherein the first axle (3) is a rear axle and the second axle (4) is a front axle with respect to a direction (S) of usual movement of the aircraft (2).

11. Aircraft (2) comprising at least one landing gear (1) according to any one of claims 1 to 10, wherein the aircraft (2) is arranged to selectively adopt first and second aircraft configurations, distinct from one another, in the first aircraft configuration, said at least one braked wheel (3a) on the first axle (3) and said at least one motorised wheel (4a) on said second axle (4) being simultaneously in contact with a running surface (P) to enable the taxiing of the aircraft, in the second aircraft configuration (2) said at least one braked wheel (3a) on the first axle (3) is in contact with a running surface (P) while said at least one motorised wheel (4a) on said second axle (4) is distanced from this running surface (P), the passage from one of these aircraft configurations to the other of these aircraft configurations being done by actuation of said first actuator (5).