RETURN SYSTEM FOR LIFTING HOOK AND HOOKING DEVICE COMPRISING SUCH A SYSTEM

Abstract

The present invention relates to a return system (10) intended to equip a hooking device comprising a housing and a load hook (30) mounted so as to be able to pivot relative to the housing, the return system being mounted between a rod (21) secured to said housing, and comprising at least one tension spring (11), a device for adjusting the force of each tension spring with a plate (12) and a connecting rod (13) adjustably attached to the plate, and a crank pin (14) situated at a free end of the connecting rod, each tension spring links the rod to said plate, the crank pin is attached to the load hook, and the return system exerts a return force on the load hook that allows said load hook to close. The present invention also relates to a hooking device equipped with such a return system.

Claims

1. Return system intended to equip a hooking device comprising a housing and a load hook mounted so as to pivot relative to the housing, the return system comprising an elastic means mounted between a rod secured to said housing and a crank pin fixed to said load hook, said return system being capable of exerting a return force on the load hook in order to allow said load hook to be closed, characterised in that it further comprises a device for adjusting the return force of the elastic means.

2. Return system according to claim 1, wherein the adjustment device of the return force of the elastic means comprises a plate connected to the elastic means and a connecting rod cooperating with said plate, the connecting rod passing through a hole of the plate and comprising a threaded portion connected to the crank pin and an adjustment nut screwed onto a portion of said threaded portion, the adjustment nut resting on the plate, the tightening of said adjustment nut making it possible to adjust an elongation of the elastic means.

3. Return system according to claim 1, wherein the elastic means comprises at least one tension spring.

4. Return system according to claim 1, in which the elastic means comprises at least two tension springs mounted in parallel.

5. Return system according to claim 3, wherein each tension spring has contiguous coils and comprises an upper hook through which said spring is suspended in a groove of the rod.

6. Return system according to claim 4, wherein each tension spring comprises a lower hook which cooperates with recesses made in the plate, said plate being suspended from the tension springs.

7. Return system according to claim 2, wherein the connecting rod comprises a curved part ending in a hole traversed by the crank pin, said crank pin and said connecting rod forming a sliding pivot connection.

8. Device for hooking loads for a lifting apparatus comprising a housing and a load hook mounted so as to pivot relative to the housing, characterised in that it comprises a return system according to claim 1.

9. Hooking device according to claim 8, wherein the load hook is pivotably mounted about a tilting axis and comprises a recess in which a part of the return system is housed, the recess having a length which allows the load hook to be tilted between a closed position and an open position in the presence of the part of the return system in said recess.

10. The hooking device according to claim 8, wherein the load hook is fixed to the crank pin of the return system along an axis offset with respect to the tilting axis of said load hook.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0023] The different figures as well as the elements of the same figure are not necessarily shown on the same scale. In all of the figures, the identical elements bear the same reference frame.

[0024] It is thus illustrated by:

[0025] FIG. 1: a partial perspective view of a hooking device equipped with a system for returning the hook according to one embodiment of the invention;

[0026] FIG. 2: a perspective view of the return system of FIG. 1;

[0027] FIG. 3: a perspective view of the return system coupled to the hook of the hooking device;

[0028] FIG. 4: another perspective view of the return system coupled to the hook, the hook being transparent to allow the connecting rod and the crank pin of the return system to be viewed;

[0029] FIGS. 5a and 5b: diagrams of the return system when the load hook is closed, FIG. 5a, and when the latter is open, FIG. 5b.

DETAILED DESCRIPTION OF EMBODIMENTS

[0030] In the embodiment described below, reference is made to a hooking device intended mainly for the transport of loads by helicopter. This example is in no way exclusive of applications to lifting and transporting loads by other apparatuses.

[0031] Such a hooking device is usually connected to a helicopter which comprises at this end fastening means such as, for example, a clevis, a bearing or bores. The hooking device then allows the suspension of the load to be transported, via a lifting attachment such as a ring or shackle.

[0032] FIG. 1 represents a partial view of a fastening device 100 comprising a return system 10, a housing 20 and a load hook 30, the load hook being pivotably mounted in the housing 20 and the return system 10 making it possible to return the load hook 30 in position relative to the housing. The hooking device further comprises other components which do not directly cooperate with the return system 10, which is the subject of the present invention, and which are known to a person skilled in the art such as the safety catch and the locking unlocking mechanism of the load hook. These elements are not shown in the drawings.

[0033] The return system 10 is placed between a transverse rod 21 secured to the housing 20 and the load hook 30, said transverse rod being arranged perpendicularly to a front plane of said housing.

[0034] FIG. 2 shows the return system 10 according to an exemplary embodiment of the invention, the return system mainly comprises two tension springs 11, a rectangular plate 12, a connecting rod 13 and a transverse crank pin 14.

[0035] According to the exemplary embodiment illustrated, the tension springs 11 are mounted in parallel between the transverse rod 21 and the rectangular plate 12, each of said springs being at contiguous coils comprising an upper hook 111 and a lower hook 112.

[0036] The transverse rod 21 comprises two grooves 211 adapted to hold the upper hooks 111 of the springs 11. Thus, the tension springs 11 are suspended from the transverse rod 21 via the upper hooks 111 each of which is placed in a groove 211 of said transverse rod. The grooves 211 limit the transverse play of the tension springs 11 relative to the transverse rod 21.

[0037] In all of the figures except in FIGS. 5a and 5b, the tension springs 11 are shown at rest, and therefore separated from the transverse rod 21 to which they are normally suspended by being tensioned, in order to better represent their elongation, or length, unloaded.

[0038] The springs 11 are mounted tensioned, or pre-loaded, between the housing 20 and the load hook 30 in order to secure the closed position of the load hook by means of a restoring force exerted permanently on said load hook.

[0039] The rectangular plate 12, according to the exemplary embodiment illustrated, is suspended from the tension springs 11 by means of recesses 121 produced for this purpose in said rectangular plate. Each lower hook 112 is placed in two recesses 121 facing one end of the rectangular plate 12, each recess being a lateral groove opening between a lower face and an upper face of said rectangular plate.

[0040] The connecting rod 13, according to the exemplary embodiment illustrated, comprises a curved portion 131 and a straight threaded portion 132, the threaded portion is inserted into a central hole of the rectangular plate 12 and is fixed to said plate by an adjustment nut 133 which is screwed onto the thread of said threaded portion. The assembly formed by the adjustment nut 133 and the threaded part 132 makes it possible to adjust the preload of the tension springs 11 by adjusting the distance between the transverse rod 21 and the plate 12.

[0041] In fact, the tightening of the adjustment nut 133 produces a downward displacement of the rectangular plate 12 thus increasing the elongation of the tension springs 11 suspended from the transverse rod 21. The usefulness of this preloading adjustment will be detailed later in the description.

[0042] The curved part 131 of the connecting rod 13 is connected to the crank pin 14, said crank pin being mounted in a sliding pivot, of axis 140, in a hole provided in the free end of said curved part.

[0043] The crank pin 14, according to the exemplary embodiment illustrated, is mounted in the load hook 30, immobilized in translation with respect to said load hook but free in rotation about its axis 140.

[0044] FIGS. 3 and 4 show the return system 10 coupled to the load hook 30. The load hook 30 comprises a recess 31, visible in FIG. 4, suitable for mounting the connecting rod 13 and the crank pin 14 in said load hook.

[0045] In a known manner, the load hook 30 is pivotably mounted in the housing 20 in relation to a tilting axis 32.

[0046] The recess 31 of the load hook 30 has a useful length allowing the displacement of the connecting rod 13 in said recess when the load hook 30 pivots about its tilting axis 32. The recess 31 further has a width allowing a determined transverse play of the connecting rod 13 mounted in sliding pivot relative to the crank pin 14.

[0047] The crank pin 14, according to the exemplary embodiment illustrated, comprises a collar 141 at each of its ends, the collars 141 blocking, to a functional clearance, the return system 10 in the load hook 30.

[0048] According to an exemplary embodiment, one of the collars 141 is dismountable to allow the pin 14 of the hook 30 to be removed, and is thus blocked by a pin 142 as shown in FIG. 2.

[0049] FIG. 5a schematically represents the return system 10 just before the opening of the hook 30, the opening of said hook being controlled by an unlocking locking mechanism (not shown). In this case, the springs 11 in this case have an initial elongation previously set with the adjustment nut 133.

[0050] FIG. 5b schematically represents the state of the return system 10 when the load hook 30 is in the open position, the open position corresponding to the release of a load not shown hooked via a lifting device 200. When the load hook 30 is unlocked, the force that the load exerts on it causes it to tilt downwards about its tilting axis 32. This tilting produces a circular translation of the crank pin 14, the axis 140 of which is offset with respect to the tilting axis 32, about the tilting axis 32, like the movement of a nacelle of a wheel carrousel. The movement of the crank pin drives a displacement of the connecting rod 13 and of the plate 12 of the return system 10, thus inducing an elongation of the springs 11 of a length l with respect to their initial elongation.

[0051] As soon as the load hook is completely released from the lifting accessory, said hook tilts upwards drawn by the crank pin under the effect of the return force exerted by the return system on said load hook.

[0052] In the light of the proportionality law between the return force and the elongation in a spring, the greater the springs 11 elongation, the greater the return force exerted on the hook. As a result, the tightening of the adjustment nut 133 makes it possible to increase the initial elongation of the springs and thus to increase the return force of said springs. This adjustment makes it possible, for example, to increase or decrease the closing speed of the hook as a function of the mass thereof.

[0053] In addition to the load distribution, another advantage of the present invention is the stability provided by two springs arranged in parallel instead of a single spring as being used in known hooking devices.

[0054] This arrangement, with four points of attachment which are the upper 111 and lower 112 hooks of the two springs 11, makes the system hyperstatic. Furthermore, the parallel mounting of the springs makes it possible to obtain a system with an equivalent stiffness which is the sum of the stiffnesses.

[0055] However, this arrangement is in no way obligatory and the return system according to the invention can operate with a single spring provided that the preload of said spring is adjustable by means of a nut which is screwed onto a threaded portion integral with the spring as described, or by any other means available to a person skilled in the art.