Device for hooking a moving element

Abstract

Device (10, 10') for hooking a moving element (T) with a hook (C), the device comprising a roller (11, 11') mounted on a shaft (12) such that it can move in translation between two end positions along a longitudinal axis of the shaft, and be returned to a rest position between the two end positions by elastic return means (18.1, 18.2).

Description

[0001]DEVICE FOR HOOKING A MOVABLE ELEMENT The present invention relates to a device for hooking a movable element such as those used in aircraft for retaining aircraft landing gear in the retracted position, for retaining cargo bay closing doors in the closed position, and more generally for retaining any movable element of the aircraft in one of its positions. BACKGROUND OF THE INVENTION Aircraft comprise a number of elements that are movable between a first position and a second position, such as landing gear or cargo bay closing doors. As illustrated in Figure 1, these movable elements are traditionally provided with an olive 1 adapted to be hooked by a hook 2 of a hooking box carried by the structure of the aircraft (or vice versa) to immobilize the movable elements in at least one of the aforementioned positions.The olive 1 is generally in the form of a body of revolution comprising a convex or cylindrical external surface for its cooperation with the hook 2, as well as an axial orifice via which the olive 1 is received freely rotating around an axis X between two cheeks 3 of a support 4 attached to the mobile element or the structure of the aircraft. By extension, any element intended to be hooked in a similar manner is called an “olive” even if its external shape is not that of an olive. It appears that in service, the hold closing doors undergo, in particular in flight or during an opening-closing sequence, deformations tending to cause a displacement of the olive 1 inside the hook 2. This is also the case for landing gear, in particular when they are fixed to relatively flexible structural elements.When the movement of the olive 1 is substantially perpendicular to the X axis, the olive 1 will tend to roll on a hooking surface of the hook 2 while rotating around the X axis. On the other hand, when the movement of the olive 1 is substantially collinear with the X axis, it will result in one of the following two phenomena. If there is no sliding between the external surface of the olive 1 and the hooking surface of the hook 2, the olive 1 will transmit all of its movement to the hook 2, which may cause structural damage to said hook 2 and / or other elements of the hooking housing. Moreover, when releasing the olive 1, the consequent friction force between the olive 1 and the hook 2 may be such as to reduce the performance of the hooking device, or even to make it impossible for the olive 1 to be released by the hook 2.If there is a slippage between the external surface of the olive 1 and the hooking surface of the hook 2, the olive 1 will slide on said hooking surface of the hook 2, which may cause, depending on the friction force existing between the olive 1 and the hook 2, more or less pronounced wear of the external surface of the olive 1 and / or of the hooking surface of the hook 2. This wear may cause adhesion between the olive 1 and the hook 2 and / or depressions in said olive 1 and said hook 2 causing a change in the balances. What is more, the friction force existing between the olive 1 and the hook 2 is transmitted to the hook 2 and to the other elements of the hooking housing, which may reduce the performance of the hooking device.To overcome the aforementioned drawbacks, there are hooking devices aimed at making the attachment of the hooking box mobile to manage significant movements of the olive 1 and hold the hooking box in place when the olive 1 is absent. In the case of landing gear, this system comprises, for example, elastic connecting rods connecting the hooking box to the structure of the aircraft, which considerably increase the weight and complexity of the hooking device. OBJECT OF THE INVENTION The invention therefore aims to propose a device with a contained and simple weight for hooking a mobile element by a locking hook making it possible to at least partially overcome the aforementioned drawbacks.SUMMARY OF THE INVENTION To this end, the invention proposes a device for hooking a movable element by a hook, comprising an olive mounted movable in translation on a shaft between two extreme positions along a longitudinal axis of the shaft, and returned to a rest position arranged between the two extreme positions by elastic return means. Thus, when the olive is hooked by a hook, any axial force transmitted by the olive to the hook is limited by the stiffness of the elastic return means, and not by the friction between the external surface of the olive and the hooking surface of the hook, which consequently reduces the wear of said surfaces. In particular, the device comprises a yoke intended to be attached to the movable element, the yoke comprising two cheeks each carrying one end of the shaft and between which the olive extends.According to a particular characteristic, the elastic return means comprise at least one helical spring extending between the olive and one of the cheeks of the yoke. In particular, the ends of the spring are each fitted onto a guide ring slidably mounted on the shaft, the guide rings being arranged so as to ensure guidance of the spring without contact with the shaft. In particular, the elastic return means comprise a first helical spring extending between one of the cheeks and the olive, and a second helical spring extending between the other of the cheeks and the olive. Advantageously, the olive comprises a body comprising an external surface delimited by a first shoulder and a second shoulder together defining a receiving area for the hook.Such a surface makes it possible in particular to limit the sliding between the olive and the hook, and therefore to limit abrasive wear and to guarantee a precise contact zone between the olive and the hook. In particular, the body comprises a first collar and a second collar respectively forming the first shoulder and the second shoulder, the first collar and the second collar each comprising an external face of frustoconical shape to form a guide ramp making it possible to engage the hook between the first shoulder and the second shoulder. The invention also relates to an aircraft hatch equipped with such a device. The invention also relates to an aircraft landing gear equipped with such a device. The invention further relates to an aircraft comprising at least one such hatch or at least one such landing gear, the hook being fixed to a structure of the aircraft.BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood in light of the following description, which is purely illustrative and non-limiting, and must be read in conjunction with the appended drawings, among which: [Fig. 1] Figure 1 is a perspective view of a device for hooking a movable element, according to the prior art; [Fig. 2] Figure 2 is a schematic view of a system for retaining a hatch of an aircraft landing gear in the closed position; [Fig. 3A] Figure 3A is a perspective view of a device for hooking the hatch of the landing gear illustrated in Figure 2, according to a particular embodiment of the invention; [Fig. 3B] Figure 3B is an axial sectional view of the device illustrated in Figure 3A; [Fig. 4A] Figure 4A is a perspective view of a variant of the device illustrated in Figure 3A; [Fig. 4B] Figure 4B is an axial sectional view of the device illustrated in Figure 4A.DETAILED DESCRIPTION OF THE INVENTION With reference to Figure 2, the invention is described here in relation to an aircraft A comprising a landing gear L articulated on a structure S of the aircraft A between a deployed position illustrated here and a retracted position in which the landing gear L is received in a hold H which can be closed by a hatch T. A double-acting cylinder V is coupled to the hatch T and allows the latter to be maneuvered between an open position allowing the deployment and retraction of the landing gear L, and a closed position in which the hatch T closes the hold H. In a known manner, the hatch T is held in the closed position by a hooking box B secured to the structure S of the aircraft A. The hooking box B is provided with a hook C allowing an olive 11 secured to the hatch T to be hooked when said hatch T arrives in the closed position. As illustrated in Figures 3A-3B, the olive 11 is in the form of a body of revolution.The body has an external surface 11.1, curved and convex, for its cooperation with a hooking surface of the hook C, as well as a longitudinal cylindrical orifice 11.2 via which the olive 11 is crossed by a hollow cylindrical shaft 12. The shaft 12 extends along an axis X and has an outside diameter slightly smaller than the diameter of the longitudinal orifice 11.2, so that the olive 11 is mounted so as to be able to rotate about the axis X on the shaft 12, but also so as to be able to move in translation along said axis X. The shaft 12 has a first end 12.1 received in a centering ring 13 with a collar which is mounted in a bore of a first cheek 14.1 of a yoke 14, and a second end 12.2, opposite the first end 12.1, received in another centering ring 13 with a collar which is mounted in a bore of a second cheek 14.2 of the yoke 14. The olive 11 thus extends between the first cheek 14.1 and the second cheek 14.2, the yoke 14 being fixed to the trapdoor T.The shaft 12 is traversed from end to end by a screw 15 having one end provided with a head 15.1 extending projecting from the first cheek 14.1, the other end of the screw 15 being provided with a thread 15.2 which extends projecting from the second cheek 14.2 and onto which a nut 16 is screwed. The screw head 15.1 and the nut 16 respectively bear against the first cheek 14.1 and the second cheek 14.2 via a support washer 17. The screw 15 and the nut 16 form a bolt arranged to hold the shaft 12 between the first cheek 14.1 and the second cheek 14.2 of the yoke 14. Between the first cheek 14.1 and the olive 11 extends a first helical compression spring 18.1 winding around the shaft 12. The ends of the first spring are each fitted onto a guide ring 19 with a collar which is slidably mounted on the shaft 12 so as to ensure guidance of the first spring 18.1 without contact with the shaft 12.One of the guide rings 19 bears against a first end of the olive 11 via a friction washer 20 interposed between the guide ring 19 and the first end of the olive 11, while the other of the guide rings 19 bears against the first cheek 14.1 via another friction washer 20 interposed between said guide ring 19 and said first cheek 14.1. The guide rings 19 are spaced apart by a first distance d1 making it possible to ensure a movement of the olive 11 towards a first extreme position in which the first distance d1 is zero. Similarly, between the second cheek 14.2 and the olive 11 extends a second helical compression spring 18.2 winding around the shaft 12. The ends of the second spring 18.2 are each fitted onto a guide ring 19 with a collar which is slidably mounted on the shaft 12 so as to ensure guidance of the second spring 18.2 without contact with the shaft 12.One of the guide rings 19 bears against a second end of the olive 11 via a friction washer 20 interposed between the guide ring 19 and the second end of the olive 11, while the other of the guide rings 19 bears against the second cheek 14.2 via another friction washer 20 interposed between said guide ring 19 and said second cheek 14.2. The guide rings 19 are spaced apart by a second distance d2 making it possible to ensure a movement of the olive 11 towards a second extreme position in which the second distance d2 is zero. The first spring 18.1 is arranged so as to exert on the olive 11 a first thrust force F1 which is substantially collinear with the axis X and which tends to move the olive 11 towards the second cheek 14.2. The first thrust force F1 increases as the olive approaches the first cheek 14.1, and conversely decreases as the olive 11 moves away from the first cheek 14.1. Similarly, the second spring 18.2 is arranged to exert on the olive 11 a second thrust force F2 which is substantially collinear with the X axis and which tends to move the olive 11 towards the first cheek 14.1. The second thrust force F2 increases as the olive 11 moves closer to the second cheek 14.2, and conversely decreases as the olive moves away from the second cheek 14.2. Thus, the olive 11 adopts, at rest, an equilibrium position arranged between the first extreme position and the second extreme position, and in which the first thrust force F1 exerted by the first spring 18.1 and the second thrust force F2 exerted by the second spring 18.2 cancel each other out, neither of the first nor second distances d1, d2 being zero. The olive 11 is said to be “floating”. The first spring 18.1 is here identical to the second spring 18.2 (same length, same number and diameter of turns, same stiffness, etc.), so that in the equilibrium position, the olive 11 is centered between the first and second cheeks 14.1, 14.2. The first distance d1 separating the guide rings 19 from the first spring 18.2 is then identical to the second distance d2 separating the guide rings 19 from the second spring 18.2. The olive 11, the shaft 12, the centering rings 13, the yoke 14, the screw 15, the nut 16, the support washers 17, the first spring 18.1, the second spring 18.2, the guide rings 19 and the friction washers 20 together form a device 10 for hooking the trapdoor T by the hook C. It will be understood that the axial force transmitted by the olive 11 to the hook C is here limited by the stiffness of the first spring 18.1 and by the stiffness of the second spring 18.2, and not by the friction between the external surface 11.1 of the olive 11 and the hooking surface of the hook C, so that the force is much lower and much more stable compared to so-called "fixed" olives. As long as a certain level of friction is maintained between the olive 11 and the hook C, the olive 11 remains stationary relative to the hook C: the friction between said olive 11 and said hook C is then beneficial. It will be noted that the first distance d1 and the second distance d2 are predetermined so as to be large enough to ensure a functional stroke of the olive 11 making it possible to limit the transmission of forces between the olive 11 and the hook C, but also small enough so that, in the event of breakage of one of the first spring 18.1 or the second spring 18.2, the olive 11 remains sufficiently close to its equilibrium position to remain functional.It will also be noted that the friction washers 20 allow rotation of the olive 11 around the axis X while controlling the resistive torque opposing the rotation of said olive 11. It will further be noted that the stiffnesses of the first spring 18.1 and of the second spring 18.2 are predetermined so that the first spring 18.1 and the second spring 18.2 maintain the olive 11 in its equilibrium position when said olive 11 is disengaged from the hook C while minimizing their restoring force. Figures 4A-4B illustrate a device 10' which is none other than a variant of the device 10 illustrated in Figures 3A-3B. The device 10' differs from the device 10 in that the body of the olive 11' comprises a slightly convex external surface 11.1' which extends between a first shoulder 11.3' and a second shoulder 11.4' defining a receiving area for the hook C. The first shoulder 11.3' and the second shoulder 11.4' are formed respectively by a first collar 11.5' and a second collar 11.6' which define an engagement zone of the hook C. The first collar 11.5' and the second collar 11.6' are shaped to ensure centering, along the X axis, of the olive 11' relative to the hook C during hooking. For this purpose, the first collar 11.5' and the second collar 11.6' comprise an external surface 11.7', 11.8' of truncated cone shape which defines a guide ramp allowing the hook to be engaged between the first shoulder 11.3' and the second shoulder 11.4', said first and second shoulders 11.3', 11.4' being spaced apart by a distance D slightly greater than a width of the hook to form a functional clearance. The external surfaces 11.7', 11.8' converge towards each other going towards the X axis.Thus, even under severe conditions of use, the sliding between the olive 11' and the hook C remains limited to the functional clearance, which limits the abrasive wear of the convex surface 11.1' of the olive 11' and / or the hooking surface of the hook C, and guarantees a precise contact zone between the olive 11' and the hook C. 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. The first spring 18.1 and the second spring 18.2 may be replaced by any elastic return means making it possible to return the olive 11, 11' to its equilibrium position (wave spring, stack of Belleville-type elastic washers, etc.). In the event of a difference in length between the first spring 18.1 and the second spring 18.2, the number or thickness of the friction washers may be adapted according to the centering requirements of the olive 11, 11'.Generally, any adjustment device may be used to, if necessary, ensure the centering of the olive 11, 11'. Although it is advantageous to have a friction washer 20 between the olive 11, 11' and each ring 19 as well as between each ring 19 and each ring 13, it would be possible to have friction washers 20 only between the olive 11, 11' and the rings 19 or between the rings 19 and the rings 13. The rings 13, 19 are optional. The device 10, 10' may comprise ball, roller or needle bearings to facilitate the rotation of the olive 11 relative to the yoke. Although the elastic return means of the device 10, 10' here comprise two springs 18.1, 18.2, they could comprise only one. Although the shoulders 11.3', 11.4' are here arranged to rest on the sides of the hook C in order to center the olive 11' relative to said hook C, they can also rest on any other part of the attachment housing B, such as for example on soles fixed to a casing of the attachment housing B. The device 10, 10' can be fixed directly on the hatch T or offset by means of a connecting rod. Although the device 10, 10' is here attached to the hatch T, it can also be directly machined on the hatch T. Although the device 10, 10' is here attached to the hatch T, it can also be attached to the landing gear L. Generally speaking, the device 10, 10' can be attached to any hatch of the aircraft A (emergency generator hatch, access door, cargo door, etc.). Even more generally, the device 10, 10' can be attached to any mobile aircraft element (structural element, slat, flap, airbrake, etc.).The bolt formed by the screw 15 and the nut 16 can be replaced by any element making it possible to hold the shaft 12 between the first cheek 14.1 and the second cheek 14.2 of the yoke 14. The first collar 11.5' and the second collar 11.6' can have a shape different from that described, and in particular any shape defining a guide ramp making it possible to engage the hook between the first shoulder 11.3' and the second shoulder 11.4'.

Claims

CLAIMS 1. Device (10, 10') for hooking a movable element (T) by a hook (C), the device comprising an olive (11, 11') mounted movable in translation on a shaft (12) between two extreme positions along a longitudinal axis (X) of the shaft, and returned to a rest position arranged between the two extreme positions by elastic return means (18.1, 18.2), the olive being further mounted movable in rotation on the shaft (12) around the longitudinal axis of said shaft.

2. Device (10, 10') according to claim 1, comprising a yoke (14) intended to be attached to the movable element (T), the yoke comprising two cheeks (14.1, 14.2) each carrying one end (12.1, 12.2) of the shaft (12) and between which the olive (11, 11') extends.

3. Device according to claim 2, in which the elastic return means comprise at least one helical spring (18.1, 18.2) extending between the olive (11, 11') and one of the cheeks (14.1, 14.2) of the yoke (14).

4. Device according to claim 3, in which the ends of the spring (18.1, 18.2) are each fitted onto a guide ring (19) slidably mounted on the shaft (12), the guide rings being arranged so as to ensure guidance of the spring without contact with the shaft.

5. Device (10, 10') according to claim 3, in which the elastic return means comprise a first helical spring (18.1) extending between one of the cheeks (14.1) and the olive (11, 11'), and a second helical spring (18.2) extending between the other of the. cheeks (14.2) and the olive (11, 11').

6. Device (10') according to any one of the preceding claims, wherein the olive comprises a body comprising an external surface delimited by a first shoulder (11.3') and a second shoulder (11.4') together defining a hook reception area.

7. Device (10') according to claim 6, wherein the body comprises a first collar (11.5') and a second collar (11.6') respectively forming the first shoulder (11.3') and the second shoulder (11.4'), the first collar and the second collar each comprising an external surface (11.7', 11.8') of frustoconical shape to form a guide ramp for engaging the hook between the first shoulder and the second shoulder.

8. Aircraft hatch (T) equipped with a device (10, 10') according to any one of claims 1 to 7. 9.Aircraft landing gear (L) equipped with a device (10, 10') according to any one of claims 1 to 7.

10. Aircraft (A) comprising at least one hatch according to claim 8 or at least one landing gear according to claim 9, the hook being fixed to a structure (S) of the aircraft.

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