Landing gear with simplified manoeuvring mechanism

Abstract

The invention relates to a landing gear (1) comprising: a leg (2) having a hinge for pivoting between a retracted position and a deployed position; a main brace (5) having a state in which the leg (2) is stabilised in the deployed position, in which position the main brace (5) defines a main force-take-up path; a mechanism for manoeuvring the leg (2) at least from its deployed position to its retracted position; and a mechanism for stabilising the leg (2) in the retracted position. The manoeuvring mechanism comprises a rotary actuator (15) which is positioned outside the main force path when the leg (2) is in the deployed position and which actuates a single crank (16), and a connecting rod (17) having a first end hinged to the leg (2) and a second end hinged to the crank (16) in order to form with the crank the mechanism for stabilising the leg (2) in the retracted position. The invention also relates to an aircraft provided with such a landing gear.

Description

[0001] LANDING GEAR WITH SIMPLIFIED MANEUVERING MECHANISM

[0002] The present invention relates to aeronautics and more particularly to an aircraft landing gear.

[0003] BACKGROUND OF THE INVENTION

[0004] Aircraft landing gears are known comprising a leg pivotally mounted on an aircraft structure between a deployed position and a retracted position. The leg is stabilized in the deployed position by means of a bracing member generally comprising two connecting rods articulated together, one of the connecting rods being coupled to the leg and the other coupled to the aircraft structure. The two connecting rods are held in a substantially aligned position by a stabilizing member forming a lock which can be unlocked to allow the leg to be raised from the deployed position to the retracted position.

[0005] To accomplish this, such landing gears typically include a release actuator to unlock the stabilizer member and break the alignment of the bracing member, and a maneuvering actuator to raise the leg to the retracted position.

[0006] The landing gear also includes a member for holding the leg in the retracted position.

[0007] The multiplicity of mechanical components holding the leg in its two positions and allowing it to be maneuvered between these two positions is a source of weight, bulk and breakdowns. This also contributes to the ecological footprint of the aircraft, a footprint that needs to be reduced. In addition, this multiplicity of mechanical components generates a relatively high cost.

[0008] SUBJECT OF THE INVENTION

[0009] The invention therefore aims to simplify and improve the means used for unlocking the extreme positions and maneuvering the landing gear.

[0010] SUMMARY OF THE INVENTION To this end, the invention provides a landing gear comprising a leg having an articulation for pivoting between a retracted position and a deployed position, a main brace having a state of stabilization of the leg in the deployed position in which the main brace defines a main path for taking up force, a mechanism for maneuvering the leg at least from its deployed position to its retracted position, and a mechanism for stabilizing the leg in the retracted position.The operating mechanism includes a rotary actuator that is positioned out of the main force path when the leg is in the extended position and that actuates a single crank, and a connecting rod having a first end hinged about a first axis to a member connected to the leg and a second end hinged about a second axis to the crank such that the connecting rod and the crank have a first relative angular position in which the first axis and the second axis are in a first alignment with respect to the actuator shaft when the leg is in the retracted position such that the connecting rod and the crank stabilize the leg in the retracted position and form the stabilizing mechanism for the leg in the retracted position.

[0011] The rotary actuator thus provides a dual function and allows for a limited number of actuators. In addition, such a configuration of the actuator makes it possible to arrange the actuator substantially at the same level in service as the articulation of the leg on the structure of the aircraft, and therefore to limit the depth of the space for receiving the landing gear in the retracted position of the leg. This results in a reduction in the overall size of the landing gear, facilitating its installation in the hold of the aircraft. In addition, this arrangement of the rotary actuator limits the stresses to which it is subjected, contributing to its durability.

[0012] According to a particular embodiment, the element to which the first end of the connecting rod is articulated is a part of the main brace and the connecting rod and the crank have a second relative angular position in which the first axis and the second axis are in a second alignment relative to the actuator shaft when the leg is in the deployed position such that the connecting rod and the crank stabilize the main brace in its holding state to form a stabilizing mechanism for the main brace in its stabilizing state.

[0013] The invention also relates to an aircraft comprising such a landing gear.

[0014] The present invention will be better understood and other characteristics and advantages will become apparent upon reading the detailed description which follows, comprising embodiments given by way of illustration with reference to the appended drawings, presented as non-limiting examples, which may serve to complete the understanding of the present invention and the description of its embodiment and, where appropriate, contribute to its definition.

[0015] BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Among the attached drawings:

[0017] [Fig. 1] Figure 1 is a schematic view of an aircraft landing gear according to a first embodiment of the invention, illustrated here in the deployed position;

[0018] [Fig. 2] Figure 2 is a view similar to Figure 1 showing this aircraft landing gear in a first intermediate position;

[0019] [Fig. 3] Figure 3 is a view similar to Figure 1 showing this aircraft landing gear in a second intermediate position; [Fig. 4] Figure 4 is a view similar to Figure 1 showing this aircraft landing gear in the retracted position;

[0020] [Fig. 5] Figure 5 is a detail view of the main strut in its aligned state;

[0021] [Fig. 6] Figure 6 is a schematic view of an aircraft landing gear according to a second embodiment of the invention, illustrated here in the deployed position;

[0022] [Fig. 7] Figure 7 is a view similar to Figure 6 showing this aircraft landing gear in a first intermediate position;

[0023] [Fig. 8] Figure 8 is a view similar to Figure 6 showing this aircraft landing gear in a second intermediate position;

[0024] [Fig. 9] Figure 9 is a view similar to Figure 6 showing this aircraft landing gear in the retracted position.

[0025] DETAILED DESCRIPTION OF THE INVENTION

[0026] With reference to Figures 1 to 9, an aircraft landing gear 1 comprises, in a manner known per se, a leg 2 having a first end provided with an articulation to a structure 3 of an aircraft along a substantially horizontal articulation axis X2 in service, to be movable between a deployed position (Figures 1 and 6) to allow landing, taxiing and takeoff of the aircraft and a retracted position (Figures 4 and 9) allowing storage of the landing gear in a hold of the aircraft. The leg 2 comprises a second end opposite the first end and carrying an axle on which one or more wheels 4 are mounted to pivot. The leg 2 is telescopic and comprises a box which is the part of the leg 2 articulated to the structure 3 and a rod which is slidably received in the box and which carries the wheels, a shock absorber being arranged in a manner known per se between the box and the rod.The landing gear 1 comprises a main bracing, here in the form of a main strut 5 comprising a pair of connecting rods 5.1, 5.2 having ends hinged to each other, the connecting rod 5.1 having an opposite end hinged to the leg 2 and the connecting rod 5.2 having an opposite end hinged to the structure 3. The connecting rods 5.1, 5.2 are hinged to each other between an aligned position in which the main strut 5 is in a state of stabilizing the leg 2 in the deployed position and a folded position in which the main strut 5 allows the landing gear 1 to be stored in the hold of the aircraft, the leg 2 being in the retracted position. In the aligned position, the connecting rods 5.1, 5.2 of the main strut 5 are in abutment against each other and the main strut 5 defines a main force-recovery path allowing transmission of forces between the leg 2 and the structure 3 of the aircraft.

[0027] According to the invention, a rotary actuator 15 of the electromagnetic type is arranged on the structure 3 of the aircraft. The actuator 15 comprises an output shaft mounted to rotate about an axis X15 substantially parallel to the axis X2 of articulation of the leg 2. The axes X2, X15 here define a substantially horizontal plane in service so that the actuator 15 is arranged substantially at the same level (or height) as the axis X2 of articulation of the leg 2. The actuator 15 is offset laterally relative to the articulation of the leg 2 and is positioned outside the main force path when the leg 2 is in the deployed position. This arrangement of the rotary actuator outside the main force path limits the stresses to which it is subjected, contributing to its durability.

[0028] The output shaft of the actuator 15 carries a crank 16 whose angular position relative to the structure 3 of the aircraft can be modified by powering the actuator 15 to rotate the output shaft of said actuator 15. The crank 16 is coupled to an element linked to the leg 2 by means of a connecting rod 17, a first end of which is articulated to said element along an articulation axis X17 and a second end of which is articulated on the crank 16 along an articulation axis X16. The articulation axes X16, X17 of the connecting rod 17 are here substantially parallel to the articulation axis X2 of the leg 2 and to the rotation axis X15 of the actuator 15. The crank 16 is the only crank actuated by the actuator 15.

[0029] Such an arrangement uniquely links the angular position of the output shaft of the actuator 15 to the angular position of the leg 2 relative to the structure 3 of the aircraft.

[0030] According to the first embodiment shown in Figures 1 to 5, the element to which the first end of the connecting rod 17 is articulated is a part of the leg 2, namely the box.

[0031] In this embodiment, the landing gear further comprises a secondary strut 50 for locking the main strut 5 and an actuator 6 for unlocking the secondary strut 50 which is known per se and makes it possible to move the connecting rods of the main strut 5 out of their aligned position (see figure 5). The secondary strut 50 comprises a first link 51 having one end hinged to the first link 5.1 and a second link 52 having a first end hinged to the second link 5.2 and a second end hinged to a second end of the first link 51. The actuator 6 is hinged on one side to the second link 5.2 and on the other to the second link 52. In the deployed position of the main strut 5, the secondary strut 50 is in an alignment position stabilizing the main strut 5 in its aligned position.The stops 53, 54 are here in the form of blocks extending at respective ends of the first and second links 51, 52 near their articulation, to form a stop defining the deployed position of the main strut 5. In the aligned position of the secondary strut 50, the second link 52, which is bent, surrounds the articulation of the first link 51 to the first link 5.1, said articulation being aligned with the articulation of the second link 52 to the second link 5.2 and the articulation of the links 51, 52 between them and is positioned between them. In this position, one side 53 of the end of the connecting rod 51 articulated to the connecting rod 5.1 comes into abutment against the inner side 54 of the elbow formed by the connecting rod 52. A traction spring 55 extends between the first connecting rod 5.1 and the second connecting rod 52 to maintain, on the one hand, the secondary strut 50 in its aligned position and, on the other hand, the stops 53, 54 in abutment against each other.

[0032] The actuator 15, the crank 16 and the connecting rod 17 form a mechanism for maneuvering the leg 2 from its deployed position to its retracted position, and a mechanism for stabilizing the leg 2 in the retracted position.

[0033] In the deployed position of the leg 2, illustrated in Figure 1, the connecting rods 5.1, 5.2 of the strut 5 are in the aligned position, abutting against each other by the stops 53 and 54 (visible in Figure 5), and the angular position of the crank 16 relative to the connecting rod 17 is such that the connecting rod 17 extends substantially in the extension of the crank 16 in an imperfect alignment. More precisely, this imperfect alignment is not perfect, in the sense that the crank 16 and the connecting rod 17 are slightly beyond their geometric alignment (which is defined when the axes X15, X16, X17 are intersecting with the same straight line). This prevents hyperstaticity and ensures that it is indeed the strut 5 which ensures the transmission of forces between the leg 2 and the structure 3.

[0034] To raise the leg 2 to the retracted position illustrated in Figure 2, the actuator 6 is powered to unlock the secondary strut 50 by misaligning the connecting rods 5.1, 5.2 of the main strut 5 relative to each other and the actuator 15 is powered to rotate the output shaft of said actuator 15, and therefore modify the angular position of the crank 16 relative to the connecting rod 17. It is understood that the rotation of the output shaft has the first effect of breaking the deployed alignment of the crank 16 and the connecting rod 17 and then of pulling on the connecting rod 17 coupled to the leg 2, which causes the leg 2 to rise to the retracted position (Figures 2 and 3).

[0035] The actuator 15 continuing to be powered, the leg 2 continues to rise to reach the retracted position in which the crank 16 and the connecting rod 17 are in a relative angular position such that the crank 16 and the connecting rod 17 are in a second substantially aligned position, called retracted alignment, in which the crank 16 and the connecting rod 17 are folded. The retracted alignment is obtained by passing the crank 16 and the connecting rod 17 slightly beyond their geometric alignment (which is defined when the axes X15, X16, X17 intersect the same straight line) to make them bear against each other substantially at the level of the axis X15 of rotation of the actuator 15 via a stop formed by one side of one end of the crank 16 (the retracted alignment is said to be overcentered in English; compare figures 3 and 4).The axis X15 is therefore between the axes X16 and X17: the connecting rod 17 is bent in such a way that the articulation axes X16, X17 intersect a straight line (illustrated in dotted lines in Figure 4) extending on one side of the output shaft of the actuator 15 opposite the stop. Thus stabilized, the crank 16 and the connecting rod 17 oppose the deployment of the leg 2 around its articulation axis X2, so that the retracted position is stable. It is noted that, in the retracted position, the actuator 15 is here between the wheel 4 and the articulation of the strut to the leg 2.

[0036] For safety reasons, it may be necessary to provide redundant effort to hold the crank

[0037] 16 and the connecting rod 17 in the retracted alignment position and thus avoid any untimely deployment of the leg 2. This effort could for example be ensured by:

[0038] - the moment of inertia of leg 2 around the X2 axis; and / or

[0039] - the “pre-crusching” force exerted by slave doors connected to the landing gear 1 and which act as springs; and / or

[0040] - the aerodynamic forces exerted in flight on the hatches connected to structure 3 of the aircraft; and / or

[0041] - a controlled action of the actuator 15, which requires very little energy; and / or

[0042] - a passive characteristic of the actuator 15 such as the engine brake, the cogging torque associated with the reduction ratio, the ratchet, etc.; and / or

[0043] - an independent spring.

[0044] Concerning the descent of the leg 2 in the deployed position, it can be carried out under the effect of gravity after having provided the energy necessary to break the retracted alignment of the crank 16 and the connecting rod 17, the actuator 15 being controlled to regulate the speed of descent of the leg 2. Indeed, the movement of the connecting rod

[0045] 17 is continuous and without singularity in the direction of descent of leg 2 so that actuator 15 is always driven in the same direction and operates as a generator. Actuator 15 can therefore be used as a brake during descent. To do this, it is of course appropriate for actuator 15 to be reversible and to be able to be driven by connecting rod 17 during descent of leg 2.

[0046] Preferably, the actuator 15 will be chosen of the simplest and most reliable type possible. If possible, a direct drive torque motor type actuator without reduction will be preferred. If a reducer should be necessary, a very reliable reducer will be preferred, for example of the deformable bell type, better known under the commercial name “harmonie drive”, having a very low probability of seizure-type failure.

[0047] According to the second embodiment shown in Figures 6 to 9, the element to which the first end of the connecting rod 17 is articulated is one of the connecting rods of the strut 5.

[0048] The actuator 15, the crank 16 and the connecting rod 17 then form a mechanism for stabilizing the strut 5 in its deployed state, a mechanism for maneuvering the leg 2 from its deployed position to its retracted position, and a mechanism for stabilizing the leg 2 in the retracted position.

[0049] In the deployed position of the leg 2 illustrated in Figure 6, the connecting rods 5.1, 5.2 of the strut 5 are in the aligned position and the angular position of the crank 16 relative to the connecting rod 17 is such that the crank 16 and the connecting rod 17 are in a first substantially aligned position, called deployed alignment, in which the connecting rod 17 extends substantially in the extension of the crank 16. More precisely, the deployed alignment is obtained by making the crank 16 and the connecting rod 17 pass slightly beyond their geometric alignment (which is defined when the axes X15, X16, X17 are intersecting with the same straight line). This alignment is called overcentered in English. The axis X16 is between the axes X15 and X17 and the crank 16 and the connecting rod 17 are supported against each other via respective stops 16.1, 17.1 (visible only in Figure 6). The stops 16.1, 17.1 are here presented in the form of fingers extending at respective ends of the crank 16 and the connecting rod 17, close to the articulation axis X16, to form a stop defining the deployed alignment.

[0050] For safety reasons, the crank 16 and the connecting rod 17 are held in the deployed alignment position by a locking member comprising, for example, at least one return spring (symbolized in FIG. 6) connecting the crank 16 to the connecting rod 17 by exerting on them a tensile force tending to keep the stops 16.1, 17.1 pressing against each other. Alternatively, any other element providing a function of returning the crank 16 and the connecting rod 17 to the deployed alignment position defined by the stops 16.1, 17.1 may be used.

[0051] To raise the leg 2 to the retracted position illustrated in Figure 9, the actuator 15 is powered to rotate the output shaft of said actuator 15, and thus modify the angular position of the crank 16 relative to the connecting rod 17. As illustrated in Figure 2, the rotation of the output shaft has the first effect of breaking the deployed alignment of the crank 16 and the connecting rod 17 against the return springs and then pulling on the connecting rod 17, which causes the connecting rods 5.1, 5.2 of the strut 5 (Figure 7) to become misaligned with respect to each other and the leg 2 to rise to the retracted position.The actuator 15 continuing to be powered, the leg 2 continues to rise to reach the retracted position in which the crank 16 and the connecting rod 17 are in a relative angular position such that the crank 16 and the connecting rod 17 are in a second substantially aligned position, called retracted alignment, in which the crank and the connecting rod 17 are folded and the strut 5 is folded. In the same way as for the deployed alignment, the second alignment is a position obtained by moving the crank 16 and the connecting rod 17 slightly beyond their geometric alignment (which is defined by the perfect alignment of the axes X15, X16, X17, the axes X15, X16, X17 then being intersecting with the same straight line) to make them bear against each other substantially at the level of the axis X15 of rotation of the actuator 15 via a stop formed by one side of one end of the crank 16 (compare figures 8 and 9). The axis X15 is located between the axes X16 and X17.The connecting rod 17 is bent in such a way that the articulation axes X16, X17 intersect a straight line (illustrated in dotted lines in Figure 9) extending on one side of the output shaft of the actuator 15 opposite the stop. Thus stabilized, the crank 16 and the connecting rod 17 oppose the deployment of the leg 2 around its articulation axis X2, so that the retracted position is stable. It is noted that, in the retracted position, the actuator 15 is located opposite the wheel 4.

[0052] Here again, it may be necessary to provide a redundant effort to maintain the crank 16 and the connecting rod 17 in the retracted alignment position and thus avoid any untimely deployment of the leg 2. This effort could for example be provided by:

[0053] - the moment of inertia of leg 2 around axis X2; and / or - the “pre-crusching” force exerted by slave doors connected to the landing gear 1 and which act as springs; and / or

[0054] - the aerodynamic forces exerted in flight on the hatches connected to structure 3 of the aircraft; and / or

[0055] - a controlled action of the actuator 15, which requires very little energy; and / or

[0056] - a passive characteristic of the actuator 15 such as the engine brake, the cogging torque associated with the reduction ratio, the ratchet, etc.; and / or

[0057] - an independent spring.

[0058] The descent of leg 2 takes place as before.

[0059] Of course, the various features, variations and / or embodiments of the present invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive. Furthermore, the invention is not limited to the embodiments described above and provided solely by way of example. It encompasses various modifications, alternative forms and other variations that may be envisaged by those skilled in the art within the scope of the present invention.

[0060] In particular, although here all the articulation axes X2, X15, X16, X17 are parallel to each other, the invention also applies to kinematics with non-parallel axes, provided that the crank 16 / connecting rod 17 assembly comes into alignment when the leg is in the deployed and / or retracted position.

[0061] The stops 16.1, 17.1 may be placed directly on the crank 16 and the connecting rod 17 as illustrated in figure 6, but also on the structure 3 of the aircraft to cooperate with one of them and stop it in the imperfect alignment or deployed position.

[0062] Although the stop defining the retracted alignment position of the crank 16 and the connecting rod 17 is here placed on said crank 16, it can also be placed on said connecting rod 17 to cooperate with the crank 16 and stop the latter in the retracted alignment position.

[0063] Although the axes X2, X15 here define a substantially horizontal plane, the actuator 15 can also be arranged so that the axis X15 is in operation above the axis X2, that is to say arranged deeper in the space for receiving the leg 2 in the retracted position.

[0064] The main bracing can be of any type, for example a telescopic bar or a plunger type.

[0065] The second stop is positioned between the connecting rod 17 and the shaft of the actuator 15, or being a part integral with said shaft, or being arranged directly between the crank 16 and the connecting rod 17.

[0066] The springs may be of a different type than those described, for example elastic leaves, and may be positioned differently in the drive train.

[0067] The invention applies to any landing gear and in particular to landing gear comprising a balance leg.

Claims

CLAIMS 1. Landing gear (1) comprising a leg (2) having an articulation for pivoting between a retracted position and a deployed position, a main bracing (5) having a stabilization state of the leg (2) in the deployed position in which the main bracing (5) defines a main force recovery path, a mechanism for maneuvering the leg (2) at least from its deployed position to its retracted position, and a mechanism for stabilizing the leg (2) in the retracted position, characterized in that the maneuvering mechanism comprises a rotary actuator (15) which is positioned outside the main force path when the leg (2) is in the deployed position and which actuates a single crank (16),and a connecting rod (17) having a first end hinged about a first axis (X17) to an element linked to the leg (2) and a second end hinged about a second axis (X16) to the crank (16) such that the connecting rod (17) and the crank (16) have a first relative angular position in which the first axis (X17) and the second axis (X16) are in a first alignment with respect to the shaft of the actuator (15) when the leg is in the retracted position such that the connecting rod (17) and the crank (16) stabilize the leg (2) in the retracted position and form the mechanism for stabilizing the leg (2) in the retracted position., 2. Landing gear according to claim 1, wherein the actuator (15) is positioned substantially at the same height as the articulation of the leg (2) in a position laterally separated from the leg joint (2).

3. Landing gear according to claim 1 or 2, in which the element to which the first end of the connecting rod (17) is articulated is a part of the leg (2) and the landing gear comprises a mechanism for locking the main brace (5) in its holding state.

4. A landing gear according to claim 1 or 2, wherein the element to which the first end of the connecting rod (17) is hinged is a part of the main brace (5) and the connecting rod (17) and the crank (16) have a second relative angular position in which the first axis (X17) and the second axis (X16) are in a second alignment with respect to the actuator shaft (15) when the leg (2) is in the deployed position such that the connecting rod (17) and the crank (16) stabilize the main brace (5) in its holding state to form a stabilizing mechanism for the main brace (5) in its stabilizing state.

5. Landing gear according to claim 4, in which the crank (16) and the connecting rod (17) are held in the second angular position by a locking member.

6. Landing gear according to claim 5, in which the locking member comprises at least one elastically deformable return element bringing the crank (16) and the connecting rod (17) back into the second alignment.

7. Landing gear according to claim 6, comprising first stops (16.1, 17.1) secured respectively to the crank (16) and the connecting rod (17) to define the second alignment in which the connecting rod (17) extends. substantially in the extension of the crank (16).

8. Landing gear according to any one of the preceding claims, comprising at least one second stop secured to one side of the actuator to define the first alignment in which the connecting rod (17) and the crank (16) are folded, the second stop being positioned between the connecting rod (17) and the shaft of the actuator (15) or being a part secured to said shaft, or being provided directly between the crank (16) and the connecting rod (17).

9. Aircraft provided with a landing gear according to any one of the preceding claims.

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