Powered wheel lander

Abstract

An aircraft landing gear comprising a leg (100) having two main wheels (104) and a powered wheel (110) positioned between the two main wheels (104) and connected to the leg (100) by a linkage mechanism (120) including at least one actuator (124) for moving the powered wheel (110) between a raised and a lowered operating position. The linkage mechanism (120) includes a swing arm (122) having a first end (122.1) articulated to the free end (102.1) of the leg, and a rocker arm (123) articulated to a second end (122.2) of the swing arm (122). The motorized wheel (110) is mounted to pivot on the second end (123.2) of the rocker arm (123), and the actuator (124) extends between the free end (102.1) of the second section (102) and the rocker arm (123). (Figure from the abbreviation: Fig. 1)

Description

Title of the invention: Motorized wheeled lander

[0001] The present invention relates to the field of aeronautics and more particularly to aircraft landing gear.

[0002] BACKGROUND OF THE INVENTION

[0003] An aircraft landing gear generally comprises a telescopic shock-absorbing leg and a box housing provided at one end with means for articulating the box housing to an aircraft structure, and a rod that slides within the box housing and protrudes from the box housing at a second end. An axle is fixed to a free end of the rod, and main wheels are mounted to pivot on the axle.

[0004] A landing gear comprising a motorized wheel for moving the aircraft on the ground (rolling, taxiing, or ground handling) without using the aircraft's main engines or an aircraft tractor is known, notably from document WO-A-2021 / 250169. The motorized wheel is generally driven by an electric motor and allows for significant fuel savings when moving the aircraft on the ground (this is referred to as e-taxiing or green taxiing).

[0005] However, since the motorized wheel is mounted on the aircraft, it constitutes, when the aircraft is in flight, additional weight and space in the cargo bay housing the landing gear. Consequently, the presence of motorized wheels on the landing gear negatively impacts the aircraft's fuel consumption in flight.

[0006] Climate change is a major concern for many legislative and regulatory bodies worldwide. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies to both new types of aircraft and those already in service, requiring the implementation of technological solutions to bring them into compliance with current regulations. Civil aviation has been actively working for several years now to contribute to the fight against climate change.

[0007] Technological research efforts have already led to very significant improvements in the environmental performance of aircraft. The Applicant takes into account the factors impacting all phases of design and development in order to obtain aeronautical components and products that are less energy-intensive, more environmentally friendly, and whose integration and use in civil aviation have moderate environmental consequences, with the aim of improving the energy efficiency of aircraft.

[0008] SUBJECT OF THE INVENTION

[0009] Thus, the invention aims in particular to improve the performance and integration of motorized wheels in landers in order to limit fuel consumption. Summary of the invention

[0010] For this purpose, according to the invention, an aircraft landing gear is provided, comprising a leg having a first section with a first end provided with means for articulation to an aircraft structure and a second telescopic section relative to the first section, an axle fixed to a free end of the second section, two main wheels mounted to pivot on the axle on either side of said free end, and a motorized wheel which is positioned between the two main wheels and which is connected to the leg by a linkage mechanism comprising at least one actuator for moving the motorized wheel between a raised position and a lowered position of use.

[0011] The linkage mechanism comprises a swing arm having a first end articulated to the free end of the second section, and a rocker arm which has a first end and a second end and which is articulated to a second end of the swing arm, the motorized wheel being mounted to pivot on the second end of the rocker arm and the actuator extending between the free end of the second section and the rocker arm, the rocker arm being arranged to extend substantially parallel to the leg when the motorized wheel is in the lowered operating position.

[0012] Thus, the rocker arm extends substantially vertically when the aircraft is resting on the ground on its main wheels and the driven wheel is in its lowered operating position. This allows for efficient transmission of engine torque between the driven wheel and the ground, limiting the forces borne by the actuator, regardless of the aircraft's direction of travel (forward or backward). The motor for the driven wheel can therefore be more accurately sized with regard to the forces required. Indeed, when the rocker arm is close to 90° relative to the ground, the force transmitted by the actuator is virtually identical in forward and reverse movement to maintain the rocker arm's position in contact with the ground and allow torque transmission to the driven wheel without slippage.If this angle is smaller (for example, less than 80°), the torque applied for reversing generates a reaction force on the rocker arm, which reduces the ground pressure exerted by the driven wheel: the actuator must then deliver more force to prevent the driven wheel from slipping. For such rocker arm angles, the structure of the driven wheel / connecting mechanism assembly would need to be dimensioned accordingly, which would impact the mass of the actuators and the structure. Orienting the rocker arm at an angle close to 90° relative to the ground therefore limits the forces transmitted through the [mechanism / system]. mechanism and thus optimize mass.

[0013] The proposed arrangement also makes it possible to limit as much as possible the adaptation of the lander to the presence of the motorized wheel, the lander retaining substantially the same structure whether it is equipped with the motorized wheel or not.

[0014] Advantageously, the lander also has all or some of the following characteristics, independently or in combination: - the lander includes a protection mechanism arranged to allow the motorized wheel to rise when a reaction force exerted on it by the ground exceeds a predetermined threshold; - the protection mechanism includes a breaking strut extending between the swing arm and the second section and having an aligned state in which the breaking strut maintains the swing arm in a lowered position substantially perpendicular to the leg and a misaligned state in which the breaking strut allows the swing arm to rise towards the landing gear leg; - a tension spring extends between the breaking strut and the second section and has a stiffness defining the predetermined threshold; - the protection mechanism includes a cylinder extending between the second section and the swing arm; - the lander includes a mechanism for locking the motorized wheel in the raised position; - the locking mechanism includes a lock integrated into the actuator; - the locking mechanism includes a latching housing arranged between the swing arm and the pendulum; - the linkage mechanism includes a support comprising a base fixed to the free end of the second section and a plate attached to the base and extending up towards the second section, the first end of the swing arm and the actuator being linked to the plate so that the support constitutes the only point of attachment of the motorized wheel to the leg.

[0015] The invention also relates to an aircraft comprising such a lander.

[0016] Other features and advantages of the invention will become apparent from the following description of particular, non-limiting embodiments of the invention. Brief description of the drawings

[0017] Reference will be made to the attached drawings, among which:

[0018] [Fig-1] [Fig.1] is a partial schematic front view of an aircraft equipped of landing gear according to the invention;

[0019] [Fig.2] [Fig.2] is a partial perspective view of a landing gear of this aircraft in deployed position;

[0020] [Fig. 3] [Fig. 3] is a partial view from below of this aircraft, showing the lander in the retracted position in its cargo bay;

[0021] [Fig. 4] [Fig. 4] is a side view of a landing gear of this aircraft in position deployed before touching the ground, with the motorized wheel in the raised position;

[0022] [Fig. 5] [Fig. 5] is a side view of a landing gear of this aircraft in position deployed while resting on the ground, with the motorized wheel in the lowered position;

[0023] [Fig. 6] [Fig. 6] is a detailed view of the lower end of this lander with the motorized wheel in the lowered position, the lander comprising a linkage mechanism according to a first embodiment;

[0024] [Fig.7] [Fig.7] is a detail view of this lower end of the lander with the motorized wheel crossing an obstacle;

[0025] [Fig.8] [Fig.8] is a detail view of the lower end of this lander with the motorized wheel in the lowered position, the lander comprising a linkage mechanism according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0026] With reference to figures 1 to 4, the braking system according to the invention is carried by an aircraft A comprising landing gear L.

[0027] Each landing gear L comprises a leg 100 having a first section formed by a box 101 and a second section formed by a rod 102 slidably received within the box 101 to form a telescopic shock absorber with it. The box 101 has a first end 101.1 provided with means for articulation to a structure of the aircraft A and a second end 101.2 from which the rod 102 protrudes, which has a free end 102.1 (visible in Figures 6 to 8) provided with two coaxial shafts 103, forming an axle, on each of which a main wheel 104 is mounted to pivot. Each shaft 103 has a central axis defining an axis X of rotation of the main wheel 104 it carries. Each main wheel 104 comprises, in a manner known per se, a hub mounted to pivot on the shaft 103 and a rim connected to the hub by a flange. The rim is encircled by a tire received between two lips of the rim.The main wheels 104 are called "main" in the sense that they are the ones that support the weight of aircraft A when it is on the ground.

[0028] The articulation means include bearings receiving a shaft for connecting the leg 100 to the structure of aircraft A, allowing the leg 100 to pivot between a retracted position in a cargo bay S of aircraft A (for flight phases; see [Fig. 3]) and a deployed position outside the cargo bay S of aircraft A (for landing, taxiing, and takeoff phases; see Figures 2, 4, and 5). The landing gear L includes a deployment mechanism, known per se and not shown here, allowing the leg to be moved 100 between these two positions.

[0029] Each lander L further includes a motorized wheel 110 which is positioned between the two main wheels 104 and which is connected to the leg 100 by a linkage mechanism 120.

[0030] The motorized wheel 110 is known in itself and incorporates an electric motor 111 comprising a stator formed on a shaft 112 having axially projecting ends on each side of the motorized wheel 110 and a rotor integral with a hub / rim assembly 113 encircled by a tire 114. The electric motor 111 is supplied with electrical energy by electrical cables not visible in the figures and is controlled in a manner known in itself.

[0031] The linkage mechanism 120 includes a support 121 comprising a base 121.1 fixed to the free end 102.1 of the rod 102 and a plate 121.2 integral with the base 121.1 and rising in front of the rod 102.

[0032] The linkage mechanism 120 also includes a swing arm 122 having a first end 122.1 articulated to the free end 102.1 of the rod 102 via the plate 121.2 and a second end 122.2 to which is articulated a portion of the articulation of a balance wheel 123 comprising two arms parallel to each other, each having a first end forming a first end 123.1 of the balance wheel 123 and a second end forming a second end 123.2 of the balance wheel 123. The drive wheel 110 extends between the second ends of the arms of the balance wheel 123, and the ends of the shaft 112 of the drive wheel 110 are fixed to these two second ends of the arms. The drive wheel 110 is thus mounted to pivot on the second end 123.2 of the balance wheel 123.

[0033] According to a first embodiment more particularly represented in figures 6 and 7, the articulation portion is located on the first end of the arms forming the first end 123.1 of the rocker 123.

[0034] According to a second embodiment more particularly represented in [Fig.8], the articulation portion is an intermediate portion between the first end 123.1 and the second end 123.2 of the rocker 123.

[0035] In these two embodiments, two actuators 124, here linear electric or hydraulic actuators, extend parallel to each other to move the driven wheel 110 between a raised position (see Figures 3 and 4) in which the driven wheel 110 cannot touch the ground G when the main wheels 104 are in contact with the ground G, and a lowered operating position (see Figures 5 to 8) in which the driven wheel 110 touches the ground G when the main wheels 104 are in contact with the ground G. The rocker arm 123 and the oscillating arm 122 are arranged to extend substantially in line with each other, substantially perpendicular to the leg 100, when the driven wheel 110 is in the raised position. The balancer 123 is arranged to extend substantially parallel to leg 100 when the powered wheel 110 is in the lowered operating position and the swing arm 122 is arranged to extend substantially perpendicular to leg 100 when the powered wheel 110 is in the lowered operating position.

[0036] Each actuator 124 is telescopic and comprises a body having one end articulated to the support 121 and a telescopic rod having a free end articulated to the rocker arm 123. The hydraulic circuit supplying the actuators 124 is conventional.

[0037] In the first embodiment, each actuator 124 extends under the oscillating arm 122 and the body of the actuator 124 is articulated to the base 121.1 and the rod is articulated to the second end of one of the arms forming the second end 123.2 of the rocker 123.

[0038] In the second embodiment, each actuator 124 extends above the oscillating arm 122 and the body of the actuator 124 is articulated to the plate 121.2 and the rod is articulated to the first end of one of the arms forming the first end 123.1 of the balance wheel 123.

[0039] In these two embodiments, each actuator 124 therefore extends between, on the one hand, the free end 102.1 of the rod 102 via the support 121 and, on the other hand, the rocker arm 123.

[0040] The linkage mechanism 120 also includes a locking mechanism for the driven wheel 110 in the raised position. This locking system ensures that the driven wheel is locked when not in use. The locking mechanism for the driven wheel in the raised position comprises two locks, each integrated into one of the actuators 124. Each lock is, for example, mounted between the body and the rod of the actuator 124 to selectively lock and unlock the sliding of the rod relative to the body. These locks and their control are known per se and can be replaced by any device with a similar function. Alternatively, the locking mechanism includes a latching housing arranged between the rocker arm 123 and the swing arm 122 to hook them together in the raised position.At least two position sensors, located in two different places, allow verification of the locking of the motorized wheel 110 in the raised position. The locking housing is known in itself and such a housing is used, for example, for locking the landing gear in the cargo bay of certain aircraft.

[0041] The linkage mechanism 120 further includes a protection mechanism arranged to allow the motorized wheel 110 to be raised when the force exerted on it by the ground G is greater than a predetermined threshold.

[0042] According to the first embodiment, the protection mechanism comprises a breaking strut 130 extending between the swing arm 122 and the free end 102.1 of the rod 102 via the support 121. More specifically, the breaking strut 130 includes a first connecting rod 131 having a first end articulated to the plate 121.2 and a second end articulated to a first end of a second connecting rod 132 having a second end articulated to an intermediate portion of the swing arm 122. The breakaway strut 130 has an aligned state in which the breakaway strut 130 holds the swing arm 122 in a lowered position substantially perpendicular to the leg 100, and a misaligned state in which the breakaway strut 130 is "broken" (the two connecting rods 131, 132 form an obtuse angle with each other) and allows the swing arm 122 to rise towards the leg 100 of the landing gear L. A tension spring 133 extends between the breakaway strut 130 and the free end 102.1 of the rod 102 via the support 121 to hold The breakaway strut in its aligned state. The tension spring 133 has a stiffness defining the predetermined threshold.Thus, during unobstructed rolling, the first connecting rod 131 is almost aligned with the second connecting rod 132 (see [Fig. 6]). The spring 133 maintains this position. When a force FG is reached, the resulting force on the spring 133 allows the spring 133 to extend. The angle between the connecting rods 131 and 132 decreases, and the ground reaction force on the wheel also decreases rapidly, without requiring control of the force delivered by the actuators 124.

[0043] According to the second embodiment, the protection mechanism comprises a hydraulic piston system (retracting cylinder 140) fixed between the swing arm 122 and the support 121 fixed to the free end 102.1 of the sliding rod 102 to hold the swing arm 122 in a lowered position substantially perpendicular to the leg 100. When the ground reaction force on the drive wheel 110 exceeds the predefined threshold, the rod of the cylinder 140 retracts into the body of the retracting cylinder 140 and the reaction force of the retracting cylinder 140 is controlled. The hydraulic retraction system with a force threshold can be implemented extremely simply with a hydraulic pressure relief valve. When the ground reaction force increases, the pressure in the retracting cylinder 140 increases and the valve releases the pressure from a predefined threshold.The hydraulic retraction system with effort threshold allows the load on the motorized wheel to be adjusted according to driving conditions (for example, passing an obstacle...).

[0044] It should be noted that the first end 122.1 of the swing arm 122, the actuator body 124, and the protection mechanism are connected to the free end 102.1 of the rod 102 by the support 121, such that the support 121 constitutes the sole attachment point of the linkage mechanism / drive wheel 110 assembly to the leg 100. This greatly facilitates the installation of this drive wheel 110, which can thus be fitted interchangeably on existing landers or, conversely, on landers specifically designed to be equipped with it. This also facilitates assembly and disassembly operations, maintenance...

[0045] In operation, when the aircraft's ground speed is less than or equal to 20 knots (37 km / h, taxiing speed limit) for example, the motorized wheel 110 is unlocked from its raised position to be brought, by the actuators 124, into its lowered position in contact with the ground G.

[0046] Before touching the ground G, the motorized wheel 110 can be driven at a rotational speed almost synchronous with the speed relative to the ground G in order to limit the forces on the actuators 124 when the motorized wheel 110 is being rotated and to limit the wear of the tire 114 of the motorized wheel 110 at the time of contact with the ground G.

[0047] The actuators 124 position the rocker arm 123 parallel to the landing leg 100, compress the tire 114 of the driven wheel 110 against the ground G, and apply a sufficient resulting force to the ground G to transmit engine torque without slippage of the driven wheel 110 on the ground G. The actuators 124 thus place the rocker arm 123 in a near-vertical position and apply a continuous force to transmit engine torque without slippage of the tire 114 on the ground G. The mass distribution on the main wheels 104 of the landing gear L, in reaction to the mass and center of gravity of the aircraft A, modifies the compression of the tires of wheels 104 and 110 and the magnitude of the ground reaction forces. This resulting force contributes to the torque transmission.

[0048] As mentioned, the rocker arm 123 has a position close to 90° (from 80° to 90°) relative to the ground G to limit the forces to be applied to the motorized wheel 110 in forward and reverse motion.

[0049] The motorized wheel 110, or the main wheels 104, may pass over an obstacle on the track (for example, lighting devices on the ground or debris). A puncture may also occur on the main wheels 104.

[0050] When passing over an obstacle, or in the event of a puncture of one or both of the main wheels 104, the load distribution on the three wheels (104, 110) of the lander L in contact with the ground is modified. The inherent deformation of the tire 114 of the driven wheel 110 can tolerate small obstacles, differences in inflation pressure between the main wheels, and minor ground irregularities. However, when a larger obstacle must be crossed, or in the event of a puncture, the protective mechanism activates to limit the ground reaction forces G on the driven wheel 110. The protective mechanism is designed to accommodate a puncture of both main wheels 104 and rolling on the rim without overloading the driven wheel 110.

[0051] When the motorized wheel 110 is in the raised position, the two locks secure the wheel in that position. The raised position of the motorized wheel 110 is determined in such a way that the motorized wheel 110 is not in contact with the ground G under any circumstances. the compression of the shock absorber, the crushing of the main wheel tires, and the attitude of aircraft A during landings and takeoffs (tail down).

[0052] It should be noted that the lander, whether equipped with or not with the motorized wheel, has an identical structure. Inspection is facilitated because the mechanism is accessible and visible without disassembly. Maintenance is simplified: indeed, the equipment can be easily disassembled and / or replaced. The location of the motorized wheel does not interfere with the mounting and dismounting of the main wheels during tire replacements (wear or puncture).

[0053] Of course, the invention is not limited to the embodiment described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0054] In particular, the structure of the lander can be modified.

[0055] The lander may comprise only one actuator or different actuators such as rotary actuators.

[0056] The breakaway strut mechanism, or retracting mechanism in general, can be doubled, symmetrically to the drive wheel, in order to tolerate a break in one of the parts of the structure and to maintain control of the angular position of the drive wheel by the actuators. In this case, the e-Taxi becomes unavailable but remains safe (damage tolerance).

[0057] The retracting principle described above can be replaced by any other force limiting mechanism such as a torque limiter (e.g. disc, ball etc.) or force limiter (ball, claw, segment, friction etc.).

Claims

Claims

1. Aircraft landing gear, comprising a leg (100) having a first section (101) with a first end provided with means for articulation to an aircraft structure and a second section (102) telescopic relative to the first section, an axle (103) secured to a free end of the second section, two main wheels (104) mounted to pivot on the axle (103) on either side of said free end, and a motorized wheel (110) which is positioned between the two main wheels (104) and which is connected to the leg (100) by a connecting mechanism (120) comprising at least one actuator (124) for moving the motorized wheel (110) between a raised position and a lowered position of use, characterized in that the connecting mechanism (120) comprises an oscillating arm (122) having a first end (122.1) articulated to the free end (102.1) of the second section (102), and a balance (123) which has a first end (123.1) and a second end (123.2) and which is articulated to a second end (122.2) of the swing arm (122), the motorized wheel (110) being mounted to pivot on the second end (123.2) of the rocker arm (123) and the actuator (124) extending between the free end (102.1) of the second section (102) and the rocker arm (123), the rocker arm (123) being arranged to extend substantially parallel to the leg (100) when the motorized wheel (110) is in the lowered position of use.

2. Landing gear according to claim 1, comprising a protection mechanism arranged to allow the motorized wheel (110) to be raised when a reaction force exerted on it by the ground is greater than a predetermined threshold.

3. The landing gear of claim 2, wherein the protection mechanism comprises a breaker strut (130) extending between the swing arm (122) and the second section (102) and having an aligned state in which the breaker strut (130) maintains the swing arm (122) in a lowered position substantially perpendicular to the leg (100) and a misaligned state in which the breaker strut (130) allows the swing arm (122) to rise towards the leg (100) of the landing gear (L).

4. A landing gear according to claim 3, wherein a tension spring (133) extends between the breaker strut (130) and the second section (102) and has a stiffness defining the predetermined threshold.

5. A landing gear according to claim 2, wherein the protection mechanism comprises a cylinder (140) extending between the second section (102) and the swing arm (122).

6. A landing gear according to any preceding claim, comprising a mechanism for locking the motorized wheel (110) in the raised position.

7. The landing gear of claim 6, wherein the locking mechanism comprises a lock integrated with the actuator (124).

8. A landing gear according to claim 6, wherein the locking mechanism comprises a latch housing disposed between the swing arm (122) and the rocker (123).

9. Landing gear according to any one of the preceding claims, in which the connecting mechanism (120) comprises a support (121) comprising a base (121.1) fixed to the free end (102.1) of the second section (102) and a plate (121.2) integral with the base (121.1) and rising opposite the second section (102), the first end (122.1) of the swing arm (122) and the actuator (124) being connected to the plate (121.2) so that the support (121) constitutes the only point of attachment of the motorized wheel (110) to the leg (100).

10. Aircraft (A) comprising a structure provided with at least one hold (S) and a landing gear (L) according to any one of the preceding claims, the first end of the first section (101) of the leg (100) being articulated to the structure in such a way that the leg (100) pivots between a position deployed outside the hold (S) and a position retracted into the hold (S).

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