Variable-length landing gear and aircraft equipped with such a landing gear

Abstract

The invention relates to a landing gear (10) comprising a supporting structure (11, 12, 13), and a damping cylinder (15) connected to a lever (17) which is hinged to the supporting structure about a hinge axis (A3) between an end position, in which the wheel is moved towards the hinge axis, and an end position, in which the wheel is moved away from the hinge axis, the end positions being on either side of an intermediate position, in which the lever and the cylinder are aligned, and the end away position being defined by a stop (21) which is secured to the supporting structure and against which the lever in the away position is applied to take up the landing forces. The invention also relates to an aircraft comprising at least one such landing gear.

Description

[0001] VARIABLE LENGTH LANDING GEAR AND AIRCRAFT EQUIPPED WITH SUCH A LANDING GEAR

[0002] The present invention relates to the field of aircraft landing gear and more particularly to retractable or retractable landing gear.

[0003] BACKGROUND OF THE INVENTION

[0004] A landing gear conventionally comprises one or more landing gears each comprising a supporting structure which comprises, for example, a leg having a first end secured to a hinge shaft to an aircraft structure and a second end carrying a balance beam at one end of which the wheel is fixed. A damping cylinder extends between the leg and the balance beam to dampen the movements of the balance beam during landing. The supporting structure is movable between an extended position in which the leg of the landing gear extends substantially vertically and a retracted position in which the landing gear is housed in a hold of the aircraft closed by a hatch.

[0005] The hold generally has a relatively small and cluttered volume which sometimes requires provision to reduce, when raising the landing gear, the distance between the wheel and the articulation of the leg to the structure of the aircraft. Such an arrangement is for example illustrated in document FR-A-2702732. This document describes a set of connecting rods connected on the one hand to the damping cylinder and on the other hand to the structure of the aircraft in such a way that the movement of the landing gear from its extended position to its retracted position also causes a movement of the first end of the cylinder causing the wheel to move closer to the articulation of the leg to the structure of the aircraft. This arrangement of connecting rods is however relatively complex and requires adjusting the length of the connecting rods on each aircraft.In addition, it is necessary to provide in the hold an attachment point for one of the connecting rods of the assembly to ensure the synchronization of the approach of the wheel in relation to the articulation of the leg and the movement of the leg in relation to the structure of the aircraft.

[0006] SUBJECT OF THE INVENTION

[0007] The invention aims in particular to propose a simple means for optimizing the accommodation of a landing gear in a hold of reduced volume.

[0008] SUMMARY OF THE INVENTION

[0009] To this end, the invention provides a landing gear comprising a supporting structure and a shock-absorbing cylinder having a first end connected by an articulation member to the supporting structure and a second end connected to a wheel.The articulation member comprises a lever having a first end articulated to the supporting structure around a first articulation axis and a second end articulated to the jack around a second articulation axis in such a way that the lever pivots around the first articulation axis between an extreme position of bringing the wheel towards the first articulation axis and an extreme position of moving the wheel away from the first articulation axis, the extreme positions being on either side of an intermediate position in which the lever and the jack are aligned and the extreme moving away position being defined by a stop secured to the supporting structure and against which the lever in the moving away position is applied to take up landing forces transmitted along a longitudinal axis of the jack.The landing gear further comprises an actuator connected to the lever and to the supporting structure for moving the lever between its two extreme positions.

[0010] Thus, the actuator makes it possible to modify the distance between the wheel and the articulation of the supporting structure to the structure of the aircraft and it is integrated into the landing gear so that it is not necessary to provide a specific attachment point in the hold. In addition, the modification of the length of the damping cylinder is adjustable directly by acting on the control of the actuator, which limits the adjustment operations during the installation of the landing gear in the hold of the aircraft. In addition, the actuator and the lever can have a relatively compact structure due to their integration on the landing gear so that their size is not detrimental to the installation of the landing gear in the hold.Finally, the landing forces are transmitted by the cylinder to the supporting structure via the lever which is in abutment against the supporting structure: the actuator does not need to be sized to withstand these forces, which helps to limit the overall size of the landing gear.

[0011] The invention also relates to an aircraft provided with at least one such landing gear.

[0012] Other characteristics and advantages of the invention will emerge from reading the following description of a particular and non-limiting embodiment of the invention.

[0013] BRIEF DESCRIPTION OF THE DRAWINGS Reference will be made to the attached drawings, including:

[0014] - figure 1 is a partial schematic front view of a landing gear installed on an aircraft according to the invention;

[0015] - figure 2 is a schematic perspective view of a landing gear according to a first embodiment of the invention;

[0016] - Figure 3 is a schematic side view of a landing gear according to the first embodiment of the invention; - Figure 4 is a partial schematic front view of a landing gear according to the first embodiment of the invention showing more particularly the articulation member of the jack to the supporting structure;

[0017] - figure 5 is a schematic perspective view of a landing gear according to a second embodiment of the invention.

[0018] DETAILED DESCRIPTION OF THE INVENTION

[0019] Figure 1 represents an aircraft 1 comprising a structure 2 in which two holds 3 are arranged, each arranged to accommodate a landing gear generally designated 10 (only a part of the wing of the aircraft 1 and the associated hold 3 are visible here).

[0020] Each landing gear 10 comprises a leg 11 having a first end 11.1 and a second end 11.2.

[0021] The first end 11.1 is secured to a shaft 12 for articulating the leg 11 to the structure 2 of the aircraft.

[0022] 1 in one of the holds 3. The shaft 12 may have one or two ends arranged in a journal to each be received in a bearing of the hold 3, or comprise one or more yokes to be connected by an axis to the structure

[0023] 2 so that the leg 11 pivots relative to the structure 2 around an axis Al here substantially parallel to the shaft 12. The articulation of the leg 11 to the structure 2 of the aircraft 1 is known in itself and will not be detailed further here.

[0024] The leg 11 comprises a second end 11.2 to which is fixed for pivoting about an axis A2 an end 13.1 of a balance beam 13 having an end 13.2 provided with an axle carrying two rotating wheels 14. The axle and the pivot axis A2 of the balance beam 13 are parallel to each other. The leg 11, the shaft 12 and the balance beam 13 form a supporting structure which is mounted on the structure 2 for pivoting about the axis A1 between a retracted position in which the landing gear 10 is housed in the hold 3 during the flight of the aircraft 1 and an extended or lowered position in which the landing gear 10 extends substantially out of the hold 3 to support the aircraft 1 during the taxiing, takeoff and landing phases. The movement of the supporting structure between these two positions is ensured by an actuator symbolized at 4 and connected to a control device 5.The control device 5 is here an electronic unit connected to position sensors of the landing gear 10 relative to the structure 2 and the actuator 5 is here an electromechanical actuator known in itself. The actuation of the landing gear 10 between its retracted and extended positions is known in itself and will not be detailed further here. Other means of controlling and actuating the landing gear, for example electrohydraulic, are of course usable.

[0025] Each landing gear 10 further comprises a damping cylinder 15 arranged to dampen the pivoting movements of the balance 13 around the axis A2.

[0026] Also referring to Figures 2 to 5, the damping cylinder 15 comprises a first end 15.1 connected to an articulation member generally designated 16 mounted on the leg 11 and a second end 15.2 articulated to the rocker 13. More precisely, the first end 15.1 is here an eye secured to the body of the damping cylinder 15 and the second end 15.2 is an eye secured to the rod of the damping cylinder 15.

[0027] The articulation member 16 comprises a lever 17 having a first end 17.1 secured to a shaft 18 pivotally mounted in a bearing 19 extending radially from the leg 11 to define a pivot axis A3 substantially perpendicular to a longitudinal axis A4 of the leg 11 and to the axis A2. The lever 17 has a second end 17.2 shaped as a yoke receiving the eye of the first end 15.1 of the damping cylinder 15 to form an articulation with axis A5 parallel to the axis A3. The eye of the first end 15.1 comprises a ball joint ensuring a spherical connection of the body of the damping cylinder 15 relative to the second end 17.2 of the lever 17.

[0028] The second end 17.2 of the damping cylinder 17 is connected to an articulation 20 (a yoke carrying an articulation axis) secured to the rocker arm 13 to define a pivot axis A6 parallel to the axis A2. The eye of the second end 15.2 comprises a ball joint ensuring a spherical connection of the rod of the damping cylinder 15 relative to the rocker arm 13.

[0029] It is understood that the lever 17 pivots around the axis A3 between an extreme position of bringing the wheels 14 closer to the axis A1 and an extreme position of moving the wheels 14 away from the axis A1. The extreme positions are on either side of an intermediate position in which the shock absorber cylinder 15 and the lever 17 are aligned, that is to say that the axes A3 and A5 intersect with a longitudinal axis A7 of the shock absorber cylinder 15 (the axes A3, A5 and A7 extending in the same plane also containing a longitudinal axis A8 of the lever 17).

[0030] The extreme distance position is defined by a stop 21 secured to the supporting structure 2, and more particularly here to the leg 11, and against which the lever 17 in the distance position is applied to take up landing forces transmitted by the jack 15 parallel to its longitudinal axis A7. It can be seen in Figure 4 that, when the lever 17 is bearing against the stop 21, the axes A7 and A8 form a non-zero angle between them, the axis A7 being inclined towards the stop 21 so that the forces transmitted by the jack 15 along the direction A7 tend to apply the end 17.2 of the lever against the stop 21.

[0031] With reference to Figures 2 to 4 and according to the first embodiment, the movement of the lever 17 between its two extreme positions is ensured by a rotary actuator 22 here electromechanical. The rotary actuator 22 comprises an electric motor having a stator secured to the end 11.1 of the leg and an output shaft linked in rotation to the shaft 18. The output shaft is here coaxial with the shaft 18. The actuator 22 thus extends between the lever 17 and the supporting structure and is connected to the control device 5 to be controlled by the latter.

[0032] The landing gear 10 here further comprises a position sensor 23 which is mounted on the leg 11 and detects the arrival of the lever 17 bearing against the stop 21. The position sensor 23 is connected to the control device 5 to provide the control device 5 with signals allowing the control device 5 to control the actuator 22. Preferably, a second position sensor, not visible in the figures, is also provided which is mounted on the leg 11 and detects the arrival of the lever 17 in the extreme approach position. The position sensors facilitate the control of the rotary actuator 22 which is controlled by the control device 5 to bring the lever 17 to the approach position when raising the landing gear, and to bring the lever 17 to the distance position when lowering the landing gear.Alternatively, it is also possible to use an angular encoder, for example of the RVDT type, integrated into the motor or driven by it so as to determine the angular position of the output shaft of the rotary actuator 22 and deduce therefrom the position of the lever 17. It is also possible to detect the arrival of the lever at the stop by monitoring the supply current of the motor of the rotary actuator 22.

[0033] It will be noted that it is possible to control the rotary actuator 22 independently of the actuator 4. It is therefore possible to choose, as a function of the duration of the movement of the lever 17 between its two extreme positions and the duration of the movement of the landing gear between its retracted and extended positions, the instant of start of the movement of the lever 17 relative to the instant of start or end of movement of the landing gear between its two positions. For example:

[0034] - the lever 17 begins its movement towards the approach position just before or after the landing gear begins its movement towards the retracted position, or

[0035] - the lever 17 begins its movement towards the approach position to arrive in the approach position just before the landing gear arrives in the retracted position.

[0036] Alternatively, it could also be envisaged to control the rotary actuator 22 to return the lever 17 to the moving away position just after the landing gear 10 has reached the retracted position. In this case, it is also envisaged to move the lever 17 to the moving towards position just before starting the movement of the landing gear 10 towards the extended position and then to bring it to the moving away position once the landing gear 10 has left the hold.

[0037] Preferably, a sensor will also be provided to detect whether the cylinder 15 is under load (when the wheels 14 are still in contact with the ground) so that the lever 17 cannot be controlled towards its approach position while the cylinder 15 is compressed.

[0038] In the second embodiment shown in Figure 5, the rotary actuator 22 is replaced by a linear actuator 32, also electromechanical here. The linear actuator 32 has a first part, here the body, connected to the supporting structure, here the leg 11, and a second part, here the rod, connected to the lever 17. More precisely, the second part of the actuator 32 is articulated to a lug 33 which extends projecting from the shaft 18 connecting in rotation the lug 33 to the first end 17.1 of said lever 17.

[0039] The landing gear 10 here further comprises a position sensor 34 which is mounted on the leg 11 and detects the arrival of the lug 34 in each of its positions 34 corresponding to the extreme positions of separation and approach of the lever 17. The position sensor 34 is for example a magnetic sensor of the Hall effect type and it is connected to an electronic unit 40 for controlling the linear actuator 32. Alternatively, it is possible to detect the positions of the rod of the linear actuator 32 relative to the body of said actuator for example by a linear sensor of the LVDT type. As previously, the position sensors facilitate the control of the linear actuator 32 which is controlled by the control device 5 to bring the lever 17 to the approach position when raising the landing gear, and to bring the lever 17 to the distance position when lowering the landing gear.

[0040] 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.

[0041] In particular, the landing gear and the aircraft may have a structure different from that described.

[0042] The landing gear may include one or more wheels, one or more axles.

[0043] The landing gear may or may not be a swinging gear.

[0044] Actuators can be electromechanical, electrofluidic or fluidic actuators.

[0045] The undercarriage may comprise a single control device for controlling all the actuators of the undercarriage, or several control devices (or units), one of which is dedicated to controlling the actuator of the lever 17.

[0046] The actuator 22, 32 can integrate an electronic control card.

[0047] The lever position detectors 17 can be fixed on the shaft 12.

[0048] The actuators 22, 32 can each be equipped with at least one rotary or linear potentiometer to ensure position detection of the movable element of the actuator.

[0049] Sequences of rapprochement / distancing other than those described are possible.

Claims

DEMANDS 1. Landing gear (10) comprising a carrier structure (11, 12, 13) and a shock-absorbing cylinder (15) having a first end (15.1) connected by a joint to the carrier structure and a second end (15.2) connected to a wheel (14), characterized in that the joint comprises a lever (17) having a first end (17.1) articulated to the carrier structure about a first joint axis (A3) and a second end (17.2) articulated to the jack about a second articulation axis (A5) such that the lever pivots about the first articulation axis between an extreme position of approach of the wheel towards the first articulation axis and an extreme position of distance of the wheel from the first articulation axis, the extreme positions being on either side of an intermediate position in which the lever and the jack are aligned and the extreme distance position being defined by a stop (21) integral with the support structure and against which the lever in the distance position is applied to take up landing forces transmitted along a longitudinal axis of the jack, and in that the landinger includes an actuator (22; 32) connected to the lever and to the support structure to move the lever between its two extreme positions.

2. Lander (10) according to claim 1, wherein the actuator is a rotary actuator (22) having an output shaft rotationally linked with the first end (17.1) of the lever (17).

3. Lander (10) according to claim 1, wherein the actuator is a linear actuator (32) having a first part connected to the carrier structure (11) and a second part connected to the lever (17).

4. Lander (10) according to claim 3, wherein the second part of the linear actuator (32) is connected to a lug (33) which projects from a shaft (18) extending along the first articulation axis (A3), said shaft rotationally linking the lug (33) to the first end (17.1) of said lever (17).

5. Lander (10) according to any one of the preceding claims, wherein the actuator (22; 32) is an electromechanical actuator.

6. Landing gear (10) according to any one of the preceding claims, wherein: - the supporting structure includes a leg (11) having a first end (11.1) attached to a shaft (12) for articulation to an aircraft structure and a second end (11.2) carrying a rocker arm (13) to one end of which the wheel (14) is fixed, - the articulation member being mounted on the leg and the second end (15.2) of the cylinder (15) being articulated on the rocker arm, - the actuator (22; 32) has a part mounted on the leg.

7. Lander (10) according to any one of the preceding claims, comprising an electronic control unit (5; 40) of the actuator (22; 32) and at least one position sensor (23; 34) connected to the electronic control unit to control the actuator according to signals from the sensor.

8. Lander (10) according to claim 7, wherein the position sensor (23) is arranged to detect a position of the lever (17).

9. Lander (10) according to claim 7, wherein the position sensor (34) is arranged to detect a position of a movable part (33) connected to the lever (17).

10. Lander (10) according to any one of claims 7 to 9, wherein the electronic control unit (5) is connected to a position sensor of the carrier structure relative to an aircraft structure.

11. Aircraft (1) comprising a structure (2) on which is articulated the supporting structure (11, 12, 13) of at least one landing gear (10) according to any one of the preceding claims.

12. Aircraft (1) according to claim 11, comprising an electronic control device (5) of the 'lander (10) to move the 'lander between a position retracted into a cargo bay (3) of the aircraft and an extended position, the control device being connected to the actuator (22; 32) to control the latter so as to move the lever (17) between its two extreme positions.

13. Aircraft according to claim 12, wherein the electronic control device (5) is arranged to bring the lever (17) into its extreme approach position before commanding the movement of the landing gear (10) to its retracted position.

14. Aircraft according to claim 13, wherein the electronic control device (5) is arranged to bring the lever (17) into its extreme approach position during the movement of the landing gear (10) towards his retracted position.

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