Retractable aircraft landing gear having a strut with an integrated actuator

Abstract

The invention relates to an aircraft landing gear (100) comprising a leg (1) intended to be mounted on an aircraft structure so as to be movable between a deployed position and a retracted position, the landing gear being provided with a decoupler strut (2) comprising: two hinge elements (2A, 2B) between which, at a knee, there is a first element (2A) intended to be coupled to the aircraft structure and a second element (2B) intended to be coupled to the landing gear; a reset member (12) arranged between the two elements and resets them to a substantially aligned position defined by respective end stops (11A, 11B). According to the invention, one of the strut elements comprises a linear actuator (4) comprising a sliding rod (7) coupled to the other strut element by means of a connecting rod (9), the entire assembly being arranged so that movement of the sliding rod of the actuator in a single direction successively decouples the strut elements and moves the landing gear from the deployed position to the retracted position.

Description

Background Art

[0001] On high-speed aircraft, the landing gear is designed to be retractable in flight. Therefore, each landing gear is mounted to be movable (usually pivotable) between an extended position and a retracted position, in which the landing gear is stored in the shaft of the aircraft.

[0002] In order to stabilize the landing gear in the deployed position, a bracket member called a "strut" is used, which is connected between the aircraft structure and the landing gear leg and, when the landing gear is in the deployed position, is strengthened by the triangulation of the strut so as to form a rigid assembly, thereby keeping the landing gear in the deployed position.

[0003] Known braces include "breaker" braces, which consist of two hinged elements, one of which is coupled to the aircraft structure and the other to the landing gear leg. When the landing gear reaches the deployed position, the two brace elements enter their substantially aligned position and automatically lock in this position, thereby stabilizing the landing gear in the deployed position. The brace's hinge (or "knee") enables this alignment to be broken when the landing gear is raised, allowing the landing gear to move freely from the deployed position to the retracted position.

[0004] The decoupler strut is locked in its substantially aligned position by means of an internal lock (e.g. in the nose landing gear of an ATR42 aircraft) or an external lock (e.g. on the nose landing gear of an Airbus A320 aircraft) in the form of a secondary strut coupled to the main strut. Locking can also be performed simply by urging the elements of the strut towards the substantially aligned position defined by the abutments using springs.

[0005] In order to be able to raise the landing gear towards the retracted position, the landing gear requires an unlocking actuator to move the struts from the substantially aligned position to the disengaged position, and an operating actuator to raise the landing gear towards the retracted position. Therefore, it is necessary to manage the order in which these two actuators are activated. Summary of the Invention

[0006] The present invention seeks to propose a landing gear that is provided with a decoupler strut and that is easy to implement.

[0007] To achieve this object, an aircraft landing gear is provided, comprising a leg for mounting on an aircraft structure so as to be movable between a deployed position and a retracted position, the landing gear being equipped with a decoupler strut comprising: two articulated elements hinged together at a knee, a first element for coupling to the aircraft structure and a second element for coupling to the landing gear; and a reset member arranged between the two elements to urge them into a substantially aligned position defined by respective abutments. According to the invention, one of the strut elements incorporates a linear actuator having a slidable rod coupled to the other strut element by means of a connecting rod, the assembly being arranged so that moving the slidable rod of the actuator in a single direction sequentially causes the elements of the strut to move out of alignment, thereby moving the landing gear from the deployed position to the retracted position.

[0008] The term "integrated" means that the linear actuator is either assembled to the relevant strut element by screw fastening or any other fastening means, or is completely integrated with the relevant strut element by having a body that directly constitutes the strut element. In this case, the body of the actuator directly bears the articulation to the other element of the strut and to one of the structures to which the landing gear and the body are coupled, which means that the body of the actuator is a structural element of the strut.

[0009] The landing gear thus has only one actuator which serves to unlock the strut and raise the landing gear towards the deployed position. The actuator is incorporated into one of the strut elements, so no additional articulation is required.

[0010] In a first embodiment, the rod slides along a sliding axis contained in a plane defined by the hinge axis of the strut element into which it is incorporated.

[0011] According to another particular aspect of the invention, the linear actuator is incorporated in one of the strut elements coupled to the legs of the landing gear.

[0012] According to a further particular aspect of the invention, one of the strut elements not carrying the linear actuator has substantially the shape of a panel.

[0013] In a second particular embodiment, the rod slides along a sliding axis which does not lie in the plane defined by the hinge axis of the strut element into which it is incorporated.

[0014] According to a further specific aspect of the invention, the abutment comprises firstly the end of a tab protruding from the strut element carrying the linear actuator and secondly the end of the connecting rod articulated to the other strut element. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention may be better understood from the following description of specific embodiments of the invention given with reference to the accompanying drawings, in which:

[0016] · Figure 1 is a schematic side view of an aircraft landing gear having a brace in accordance with a first specific embodiment of the present invention;

[0017] · Figure 2 Is assembled to Figure 1 A perspective view of the landing gear struts, with the connecting rods drawn with dotted lines for greater clarity;

[0018] · Figure 3 is in the locked position Figure 1 Cross-sectional view of the strut;

[0019] · Figure 4 is similar to Figure 3 , showing the strut in an unlocked position, with the strut alignment broken;

[0020] · Figure 5 is a schematic diagram of the landing gear frame and associated struts during lift, the figure showing the deployed position with the struts in a substantially aligned position;

[0021] · Figure 6 is a schematic diagram of the landing gear frame and associated struts during lift, the figure showing the position after the strut alignment has been broken during lift;

[0022] · Figure 7 is a schematic diagram of the landing gear frame and associated struts during lift, the figure showing the retracted position;

[0023] · Figure 8 is similar to the variant embodiment of the present invention Figure 3 ; and

[0024] · Figure 9 is similar to another variant embodiment of the present invention Figure 3 view. DETAILED DESCRIPTION

[0025] refer to Figure 1 The present invention relates to an aircraft landing gear 100 comprising a leg 1 carrying one or more wheels at its bottom end and being hingedly mounted to an aircraft structure (not shown) about an articulation axis X1 (the end being visible in the figure). The leg 1 is stabilized in the deployed position by a disconnector strut 2 comprising a lower element 2A articulated to the leg about an articulation axis X2, and an upper element 2B articulated to the aircraft structure about an articulation axis X3, the lower element 2A and the upper element 2B being articulated to each other about an articulation axis X4. In the present example, all articulation axes are parallel to each other. As Figure 2As shown, the upper element 2B is roughly in the shape of a panel, while the lower element 2A is essentially composed of a cylinder 3 of a hydraulic actuator 4, which carries a lug 5 at its end for articulation to the leg 1 around an articulation axis X2 and an ear shaft 6 for articulation to the upper element 2 around an articulation axis X4. The cylinder 3 of the hydraulic actuator 4 thus forms the structure of the lower element 2A and carries the means for coupling it to the leg 1 and to the upper element 2B. Inside the cylinder 3 is mounted a slidable rod 7 associated with a piston 8, which is mounted so as to slide in a sealed manner inside the cylinder 3, thereby defining two hydraulic chambers. In the present example, the sliding axis Y of the slidable rod 7 is included in the plane defined by the articulation axes X2 and X4 of the lower element 2A, but this is not essential, as will be explained below with reference to Figure 8 and 9 shown.

[0026] The end of the slidable rod 7 is coupled to the end of a connecting rod 9, the other end of which is hinged to a fork 10 protruding from the upper element 2B. In this example, the connecting rod 9 is curved to avoid interference with other parts of the strut 2, but it could be completely straight if the structure allows. Thus, the slidable rod 7 is coupled to the upper element 2B via the connecting rod 9.

[0027] like Figure 1 、 2 As shown in Figures 3 and 4, the abutments 11A, 11B are positioned to define the basic alignment position of the lower element 2A and the upper element 2B. In this example, the basic alignment position corresponds to the "over-center" position, in which the articulation axis X4 slightly extends beyond the plane P defined by the articulation axes X2 and X3. In this example, the abutments 11A, 11B comprise the ends of a support (tag) 11 that protrudes from the cylinder 3 of the hydraulic actuator 4 and presses against the upper element 2B, in particular indirectly by contact with the end of the connecting rod 9 that is itself articulated to the upper element 2B. In a completely equivalent manner, the abutments 11A, 11B can be arranged directly between the lower element 2A and the upper element 2B, or indeed between the connecting rod 9 and the upper element 2B, as long as they define the basic alignment position of the lower element and the upper element. A return spring 12 is arranged between the lower element 2A and the upper element 2B to encourage the lower element and the upper element to abut, thereby keeping them in the basic alignment position. Therefore, any movement of the leg 1 to extend the struts 2 only results in a geometric realignment, wherein the articulation axis X4 moves toward the plane P but not beyond it. Once this movement is complete, the lower element 2A and the upper element 2B are brought back into abutment under the influence of the return spring 12. Conversely, any movement of the leg 1 to compress the struts 2 confirms the abutment between the lower element 2A and the upper element 2B. Therefore, the substantially aligned position is a stable position.

[0028] Reference below Figures 5 to 7The operation of the brace 2 of the present invention will be described. Figure 5 As shown, the landing gear 100 is initially in the deployed position (corresponding to Figure 1 (see position). In this position, strut 2 is held in its generally aligned position by spring 12, which pushes lower element 2A and upper element 2B into abutment. Strut 2 then forms a rigid assembly, triangulating leg 1 to maintain it in the deployed position. If necessary, this position can be confirmed by energizing hydraulic actuator 4, thereby retracting slidable rod 7.

[0029] To disconnect the alignment of the struts 2, thereby unlocking the deployed position of the landing gear, the hydraulic actuator 4 is energized to extend the slidable rod 7. The rod then pulls the connecting rod 9, thereby moving the lower element 2A and the upper element 2B towards the disconnected position against the return spring 12, as shown in FIG. Figure 6 and Figure 4 As shown in these figures, it can be seen that the axis X4 of the knee of the strut 2 has reached the other side of the plane P defined by the hinge axes X2 and X3. The strut 2 is thus unlocked, so that the leg 1 is no longer held in the deployed position. Thereafter, by continuing to extend the slidable rod 7, it continues to pull on the connecting rod 9, thus forcing the lower element 2A and the upper element 2B to fold, thereby moving the leg 1 towards the retracted position, as shown in FIG. Figure 7 Thus, the same hydraulic actuator 4 can be used both to unlock and to raise the landing gear towards its retracted position.

[0030] To perform the opposite movement, it is sufficient to allow gravity and aerodynamic forces to push the landing gear downwards, adjusting the speed of descent of the landing gear towards its deployed position if necessary by throttling the fluid exhausted from the full chamber of the hydraulic actuator 4. Under the action of the spring 12, the strut 2 automatically realigns itself.

[0031] exist Figure 8 and Figure 9 In the variant embodiment shown, the hydraulic actuator 4 can be arranged so that the sliding axis Y of the rod is not contained in the plane P' defined by the articulation axes X2 and X4 (in other words, the sliding axis Y of the rod does not lie in the plane P'). Figure 8 In the arrangement shown, the sliding axis Y of the slidable rod 7 still intersects the hinge axis X2, while Figure 9 In the illustrated arrangement, the sliding axis Y does not intersect either of the articulation axes X2 and X4. This degree of freedom in the arrangement makes it possible to optimize the position of the sliding axis of the slidable rod relative to the articulation axes X2 and X4. Allowing the articulation axis X4 to be offset from the sliding axis Y also provides more options for connecting the articulation X4.

[0032] The invention is not limited to the above description, but on the contrary covers any variant coming within the ambit defined by the accompanying claims.

[0033] In particular, although the linear actuators of the struts are described above as hydraulic actuators, electric or electromechanical linear actuators may equally be used.

[0034] Although the strut element incorporating the linear actuator has been described above as being connected to the lower element of the leg of the landing gear, the linear actuator may naturally be incorporated into another strut element.

[0035] Although the cylinder of the linear actuator is described above as carrying lugs and trunnions such that the cylinder forms the structure of one of the strut elements, the cylinder of the linear actuator may alternatively be attached to the strut element, for example by means of screws or any other assembly means.

[0036] Finally, although in the above description it is necessary to extend the slidable rod in order to unlock and fold the stays, it is naturally possible to provide a coupling that unlocks and folds the stays by retracting the slidable rod.

Claims

1. An aircraft landing gear (100), comprising a leg (1) for mounting on an aircraft structure so as to be movable between a deployed position and a retracted position, the landing gear being equipped with a decoupler strut (2), the decoupler strut (2) comprising: A first element (2B) and a second element (2A) are hinged together at a knee, the first element (2B) being intended to be coupled to the aircraft structure and the second element (2A) being intended to be coupled to the landing gear; a reset member (12) being arranged between the first element and the second element to urge them into a substantially aligned position defined by respective abutments (11A, 11B), the landing gear being characterized in that one of the first and second elements is combined with a linear actuator (4), the linear actuator having a slidable rod (7) coupled to the other of the first and second elements by means of a connecting rod (9), the aircraft landing gear being arranged such that moving the slidable rod of the actuator in a single direction sequentially causes the first and second elements of the decoupler strut to move out of alignment and the landing gear to move from the deployed position to the retracted position.

2. The landing gear according to claim 1, characterized in that The linear actuator has a body (3) in which the slidable rod (7) slides and forms one of the first element (2B) and the second element (2A) in which the linear actuator is incorporated, the body carrying coupling members (5, 6) for coupling the one of the first element and the second element in which the linear actuator is incorporated to the other of the first element and the second element and also to the leg and the aircraft structure to which the one of the first element and the second element in which the linear actuator is incorporated is attached.

3. The landing gear according to claim 2, characterized in that The slidable rod (7) slides along a sliding axis (Y) contained in a plane defined by the articulation axes (X2, X4) of the first element (2B) and the second element (2A) to which the slidable rod is coupled.

4. The landing gear according to claim 1, characterized in that The linear actuator (4) is incorporated in the first element (2B) and the second element (2A) coupled to one of the legs of the landing gear.

5. The landing gear according to claim 4, characterized in that One of the first element (2B) and the second element (2A) that does not carry the linear actuator has a general panel shape.

6. The landing gear according to claim 2, characterized in that The slidable rod (7) slides along a sliding axis (Y) which is not located in a plane (P') defined by the articulation axes (X2, X4) of the first element (2B) and the second element (2A) to which the slidable rod is attached.

7. The landing gear according to claim 1, characterized in that The abutment (11A, 11B) comprises firstly the end of a tab (11) protruding from the first element (2B) and the second element (2A) carrying the linear actuator and secondly the end of the connecting rod (9) articulated to the other of the first and second elements.

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