Device for locking aircraft landing gear

Abstract

The invention relates to an aircraft landing gear (1), comprising: a strut assembly (3) hinged at its upper end to a structural element of the aircraft so as to pivot between a deployed state and a retracted state; an interlocking system comprising a drawbar, the drawbar comprising an arm (11) hinged to the strut assembly (3) via a lifting pin (23), the lifting pin being carried by two lugs (19, 21) of a spreader (18) of the strut assembly (3), the arm (11) having a head (22) at its end through which the pin passes and which is located between the lugs (19, 21); a lifting jack (14), a first end of which is connected to a first end of the lifting pin (23), the first end of the lifting pin being located outside the spreader (18), a first end stop (27) carried at the first end of the lifting pin (23) exceeding the jack (14), and a second end stop (28) carried at the second end of the pin. The landing gear comprises a system for locking the translation of the lifting pin (23) in the event of a breakage of the lifting pin (23) between the first end and the spreader (18).

Description

Technical Field

[0001] The present invention relates to ensuring the operation of an aircraft landing gear in the event of a breakage of one of the hinge pins used to deploy the landing gear. Background Art

[0002] An aircraft landing gear comprises a leg including a strut assembly in which a lower portion carrying a set of wheels slides in a cushioned manner. The strut assembly is hinged at its upper end to a structural element so that the entire assembly can pivot about a main axis for deployment and retraction. Furthermore, an interlocking system is provided to lock the entire assembly in the deployed position.

[0003] The interlocking system includes a primary tie rod comprising panels and links hinged to each other, the panels being hinged to the structure and the links being hinged to the lower portion of the strut assembly, and a secondary tie rod to maintain alignment of the panels and links in the interlocking configuration.

[0004] The secondary tie rod includes two arms hinged to each other, a first arm of the two arms is also hinged to a hinge connecting the panel to the connecting rod, and a second arm of the two arms is also hinged to the upper part of the support rod assembly.

[0005] The whole is moved from its retracted to its extended position by means of a jack, one end of which is connected to the structural element and the other end of which is connected to the upper part of the strut assembly by means of a so-called lifting pin, the central part of which also carries the second arm of the secondary tie rod. This lifting pin is carried by a spreader rigidly attached to the strut assembly.

[0006] Deployment of the landing gear involves controlling the jacks to extend, which causes the strut assembly and the entire landing gear to pivot due to the offset between the lift pins and the main axis of the strut assembly.

[0007] The panels and links of the primary tie rod are then unfolded from their folded state until they extend into extensions of each other. Similarly, the arms of the secondary tie rod are also unfolded until they extend into extensions of each other to occupy their interlocked positions.

[0008] If the end of the lifting pin carrying the jack breaks, the lifting pin is likely to move and break away from the spreader that carries it, so that the lifting pin no longer carries the arm of the secondary tie rod. The landing gear is then no longer interlocked in the deployed position, making landing impossible.

[0009] The object of the present invention is to provide a solution to this drawback. Summary of the Invention

[0010] To this end, an object of the present invention is an aircraft landing gear comprising a strut assembly articulated to a structural element of the aircraft so as to pivot between a deployed state and a retracted state, said landing gear comprising:

[0011] a jack for retracting and extending the landing gear, said jack comprising an operating head connected to a first end of a lifting pin carried by two lugs of a spreader of the strut assembly, said first end being located outside said spreader;

[0012] - an interlocking system comprising a drawbar comprising an arm hinged to the upper part of the strut assembly via the lifting pin, the end of the arm having a head positioned between the lugs of the spreader and through which the lifting pin passes;

[0013] a first end stop carried by the lift pin at a first end of the lift pin and a second end stop located at a second end of the lift pin;

[0014] Characterized in that the aircraft landing gear comprises a system for locking the translation of the lifting pin in the event of a breakage of the lifting pin between the first end of the lifting pin and the spreader.

[0015] Thus, even if the end of the lifting pin connected to the operating jack breaks, the invention makes it possible to ensure the interlocking of the deployed landing gear. In other words, failure of the lifting function does not lead to failure of the interlocking of the landing gear in the event of a lifting pin breakage.

[0016] The invention also relates to a landing gear defined in that the second stop comprises a shoulder formed at the second end of the lifting pin and in that the locking system comprises a locking member axially facing the shoulder and rigidly integral with the spreader.

[0017] The invention also relates to a landing gear defined in that the locking member is rigidly attached to the spreader by being fixed to a ring carried by the lug and forming a bearing for the lifting pin, the ring being rigidly attached to the lug carrying the ring.

[0018] The invention also relates to a landing gear defined in such a way that the ring is rigidly attached to the hole of the lug by shrink fitting.

[0019] The invention also relates to a landing gear defined in that said locking member is a rod having a length greater than the diameter of said shoulder.

[0020] The invention also relates to a landing gear defined in that the ring comprises two tabs projecting radially beyond the shoulder and two bolts, each of the bolts passing through one end of the rod and one radial tab.

[0021] The invention also relates to a landing gear defined in that the locking system comprises a radially extending screw passing jointly through the head of the arm and the lifting pin.

[0022] The invention also relates to a landing gear defined in such a way that the screw passes through the head and the lifting pin and is retained by a nut threaded onto the end of the screw. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is an overall perspective view showing the landing gear;

[0024] Figure 2 is a perspective view of the upper portion of the landing gear;

[0025] Figure 3 is a perspective view through the lifting pin of the landing gear strut assembly with its operating jack and connection to the tie rod arm;

[0026] Figure 4 is a perspective view of a landing gear strut assembly through its lifting pins, its operating jacks and its connections to the tie rod arms, and fitted with a locking system according to the present invention;

[0027] Figure 5 is a cross-sectional view of the present invention applied to a landing gear;

[0028] Figure 6 is a perspective view of a landing gear strut assembly through its lift pin and its operating jack and its connection to the tie rod arm and having a locking bolt installed according to an alternative embodiment of the present invention;

[0029] Figure 7 is a cross-sectional view of an alternative embodiment of the present invention applied to a landing gear. DETAILED DESCRIPTION

[0030] like Figure 1 As shown, the landing gear 1 generally comprises a leg 2 including a strut assembly 3 in which a lower part 4 carrying a set of wheels 6 slides in a damped manner.

[0031] The strut assembly 3 is hinged at its upper end to a structural element of the aircraft so that the entire landing gear can be pivoted about a transversely extending main axis of rotation AP in order to be able to deploy and retract. In addition, an interlocking system is provided to lock the entire landing gear in the deployed position, such as Figure 1 shown.

[0032] The interlocking system comprises a primary tie rod comprising a panel 7 and a link 8 hinged to each other, the panel 7 being hinged to a structural member of the aircraft and the link 8 being hinged to the lower part of the strut assembly, and the interlocking system further comprises a secondary tie rod to keep the panel 7 and the link 8 aligned with each other in the interlocking configuration.

[0033] The secondary tie rod comprises two arms 9 and 11 hinged to each other, arm 9 being hinged to the hinge connecting the panel 7 to the link 8, and arm 11 being hinged to the upper part of the strut assembly 3. A pair of springs 12 and 13 keep the arms 9 and 11 extended relative to each other, so as to lock the entire landing gear in the deployed state. Figure 1 shown.

[0034] The entire landing gear is moved from its retracted state to its extended state by means of a jack 14 comprising a body 16 in which slides a rod 17. The ends of the body 16 are connected to structural elements of the aircraft, while the ends of the rod 17 are connected to the upper part of the strut assembly 3.

[0035] Deployment of the landing gear 1 involves controlling the jacks 14 to deploy, which causes the strut assembly 3 and the entire landing gear to pivot about the axis AP due to the offset between the lift pins 23 and the axis of rotation AP of the strut assembly (the lift pins and the axis of rotation are parallel to each other).

[0036] During this deployment process, the panel 7 and the link 8 begin to unfold naturally from their folded state until they become extensions of each other. Similarly, the arms 9 and 11 also unfold naturally until they become extensions of each other, so as to occupy the interlocking position of the entire landing gear, in which they are held by the springs 12, 13.

[0037] As in Figure 2 and Figure 3 As can be seen more clearly in FIG, the upper portion of the strut assembly 3 comprises a spreader 18 comprising a first lug 19 and a second lug 21 carrying a lifting pin 23 oriented transversely, ie parallel to the main axis AP, but offset therefrom.

[0038] A lifting pin 23, held by the lugs 21 and 19, carries in its central region (i.e. between these lugs) the head 22 of the arm 11 through which the lifting pin passes, and projects beyond the first lug in order to receive an operating head 24 extending from the rod 17 of the jack 14, which is connected to the pin via this operating head by a rotary joint.

[0039] The translation of the lift pin 23 is locked by a first end stop 27 and a second end stop 28. The first stop 27 grips the first end of the lift pin 23, i.e., the end closest to the first lug 19, to form an obstruction with a diameter greater than the nominal diameter of the pin. The second stop 28 is formed by a shoulder 30 at the end of the second end of the lift pin 23 (i.e., the end closest to the second lug 21). The shoulder 30 has a diameter greater than the nominal diameter of the pin, thereby obstructing the axial movement of the lift pin 23. The operating head 24 of the jack 14, which surrounds the lift pin 23, is located between the first lug 19 and the first stop 27.

[0040] In the example of the landing gear shown in the figure, Figure 5 and Figure 7 As shown, the lifting pin 23 is carried by the lugs 19 and 21 through which it passes, via two pairs of rings 29, 31, 32, 33. These two pairs of rings form bearings that enable the pin to pivot on its own, for example when the landing gear is moved from one state to another.

[0041] The head 22 is carried by the lifting pins 23 via another pair of rings 34 , 36 forming bearings that redundantly enable the head 22 to rotate relative to the lifting pins 23 carrying it.

[0042] In the event that the lifting pin 23 breaks between its first end and the first lug (e.g. due to the force exerted in this area by the operating head 24 of the jack actuating the lifting pin), the lifting pin 23 may move in the direction of movement from the first spreader to the second spreader and away from the detachment spreader 18. In practice, such a migration of the pin is facilitated by vibrations during operation and may result in the pin being completely detached from its housing.

[0043] More specifically, in this case, the lifting pin 23 is no longer held by the first stop 27, which allows the lifting pin to translate toward the second lug. In this case, the arm 11 is no longer held, so that the interlocking in the deployed state of the landing gear is no longer ensured.

[0044] According to the present invention, a locking system 37 is provided to lock the second end of lift pin 23 in both directions. More specifically, second ring 33 is shrink-fitted into the hole in second lug 21 that receives it, so as to be rigidly integral with the lug, rather than being able to pivot within the hole in which it is received. Second ring 33 includes two radial tabs 38 and 39 that extend in opposite directions and radially relative to axis AP, so as to project radially beyond shoulder 30.

[0045] The shrink fit of the ring 33 can be achieved by an interference fit of the ring in the hole, where the ring is installed by squeezing. Alternatively, the shrink fit ring can be installed by cooling the ring so that the ring contracts before being installed in the hole, so that it can expand when reheated.

[0046] Furthermore, a locking rod 41 extends radially so as to face the shoulder 30, i.e., the second end of the pin 23, thereby hindering the axial movement of the pin. The total length of the rod 41 is greater than the diameter of the shoulder 30 and corresponds to the distance separating the ends of the tabs 38 and 39. The rod comprises a body 42 from which extend ends 43, 44, each secured to one of the tabs 38 and 39.

[0047] As in Figure 4 and Figure 5 As can be seen in FIG, ends 43 and 44 of rod 41 bear on tabs 38 and 39 in direction AP and are thicker in direction AP than body 42 of the rod, so that during normal operation of the landing gear, body 42 does not bear on the second end of lifting pin 23, i.e. shoulder 30.

[0048] Each end of the rod 41 is fixed to a corresponding tab of the second ring 33 by two bolts 46 and 47 extending in the AP direction, each bolt passing through one end of the rod and one radial tab of the ring 33 .

[0049] In the event that the lift pin 23 breaks at the first end, the first stop 27 no longer functions properly, but the movement of the lift pin 23 is blocked by the rod 41 on which the shoulder 30 then bears. In this case, the movement of the lift pin 23 in the opposite direction is still blocked by the shoulder 30 bearing on the second ring 33 (i.e., on the second lug).

[0050] Alternatively, a bolt 51 may be provided which passes jointly through the head 22 and the lifting pin 23 in order to keep the pin fixed in translation even when either of the end stops 27 , 28 can no longer ensure translational locking.

[0051] like Figure 6 As shown, a bolt 51 extends radially relative to the lifting pin 23 through which it passes. The bolt comprises a screw 52 having a head 53 which bears on the outer surface of the head 22 of the arm 11 and from which extends a rod 54 whose threaded end receives a nut 55.

[0052] More specifically, the rod 54 passes in sequence through the wall of the head 22, the wall of the lifting pin 23, which is tubular here, then again through the wall of the lifting pin 23 and again through the wall of the head 22 so as to project from the opposite side of the head 22, where it includes a threaded end 56 that receives a nut 55 supported on the external face of the head 22.

[0053] When the bolt 51 is in place and passes through the head 22 and lift pin 23 , the bolt inhibits the head 22 from rotating relative to the lift pin 23 , but does not prevent the landing gear from deploying as the landing gear is still free to pivot relative to the lugs 19 and 21 .

[0054] Mounting the bolt on an existing landing gear first involves drilling directly through the head 22 of the arm 11 so as to also penetrate the lifting pin 23 carrying it, in effect forming two radial through-holes 57 and 58 through the head 22 and two further aligned radial through-holes 59 and 61 through the lifting pin 23. The shank 54 of the screw 52 is then engaged through these aligned holes to receive, at its free threaded end 56, a nut 55 which is then appropriately tightened.

Claims

1. An aircraft landing gear (1) comprising a strut assembly (3) articulated to a structural element of the aircraft for pivoting between a deployed state and a retracted state, the landing gear (1) comprising: - a jack (14) for retracting and extending the landing gear, the jack (14) having an operating head (24) connected to a first end of a lifting pin (23) carried by two lugs (19, 21) of a spreader (18) of the strut assembly (3), the first end being located outside the spreader (18); - an interlocking system comprising a drawbar comprising an arm (11) articulated to the upper part of the strut assembly (3) via the lifting pin (23), the end of the arm (11) having a head (22) positioned between the lugs (19, 21) of the spreader (18) and through which the lifting pin (23) passes; a first end stop (27) carried by the lifting pin (23) at a first end of the lifting pin and a second end stop (28) located at a second end of the lifting pin (23); Characterized in that the aircraft landing gear comprises a locking system for locking the translation of the lifting pin (23) in the event of a breakage of the lifting pin (23) between the first end of the lifting pin and the spreader (18).

2. The landing gear according to claim 1, wherein: The second end stop (28) comprises a shoulder (30) formed at the second end of the lifting pin (23), and wherein the locking system comprises a locking member axially facing the shoulder (30) and rigidly integral with the spreader (18).

3. The landing gear according to claim 2, wherein: The locking member is rigidly attached to the spreader (18) by being fixed to a ring (33) carried by the lug (21) and forming a bearing for the lifting pin (23), the ring (33) being rigidly attached to the lug (21) carrying the ring.

4. The landing gear according to claim 3, wherein: The ring (33) is rigidly attached to the hole of the lug (21) by shrink fitting.

5. The landing gear according to claim 4, wherein: The locking member is a rod (41) having a length greater than the diameter of the shoulder (30).

6. The landing gear according to claim 5, wherein: The ring (33) comprises two tabs (38, 39) projecting radially beyond the shoulder (30) and two bolts (46, 47), each of the bolts passing through one end of the rod (41) and one radial tab (38, 39).

7. The landing gear according to claim 1, wherein: The locking system comprises a radially extending screw (52) which passes jointly through the head (22) of the arm (11) and the lift pin (23).

8. The landing gear according to claim 7, wherein: The screw (52) passes through the head (22) and the lift pin (23) and is retained by a nut (55) threadedly connected at the end of the screw.

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