US-12617657-B2 - Method for protecting a lifting member against an overload and device implementing this method

US12617657B2US 12617657 B2US12617657 B2US 12617657B2US-12617657-B2

Abstract

A method for protecting a lifting member against an overload is described. The lifting member includes a lifting drum over which a cable is wound at the end of which a load is fixed. The lifting drum is mechanically connected to an electric motor capable of ensuring its rotation. The mechanical connection includes a clutch or equivalent device, has at least two distinct operating thresholds: a first threshold, the exceeding of which generates the freewheel operation of the lifting drum with respect to the kinematic chain coming from the electric motor, and a second threshold, of value greater than that corresponding to the nominal load of the lifting member, but of value less than that of the first threshold, generating the braking of the rotation of the lifting drum, and an attempt to progressively stop said rotation of the drum.

Inventors

Thomas THUBET
Sébastien DECREUSEFOND

Assignees

REEL

Dates

Publication Date: 20260505
Application Date: 20230926
Priority Date: 20221216

Claims (13)

1 . A method for protecting a lifting member against an overload, the lifting member comprising a lifting drum on which a cable is wound, cable at the end of which a load is fixed, said lifting drum being mechanically connected to an electric motor capable of ensuring its rotation, the mechanical connection comprising a clutch or equivalent device, wherein said method comprises at least two distinct operating thresholds: a first threshold, the exceeding of which generates a freewheel operation of the lifting drum with respect to a kinematic chain coming from the electric motor; a second threshold, of a value greater than that corresponding to a nominal load of the lifting member, but of a value less than that of the first threshold, generating a braking of the rotation of the lifting drum and an attempt to progressively stop said rotation of the lifting drum.
2 . The method for protecting a lifting member against an overload according to claim 1 , further comprising, in the case of an exceeding of said first threshold, a step consisting of attempting the re-coupling of the lifting drum on the kinematic chain intervening according to a determined periodicity.
3 . The method for protecting a lifting member against an overload according to claim 2 , wherein the determined periodicity is less than 5 seconds.
4 . The method for protecting a lifting member against an overload wherein the lifting drum belongs to a capstan system associated with a storage drum, according to claim 1 , method wherein the exceeding of said first threshold generates the braking of the rotation of the storage drum, in order to preserve a minimum strain of the cable extending between the capstan and the storage drum.
5 . The method for protecting a lifting member against an overload according to claim 1 , wherein generating the braking of the rotation of the lifting drum and an attempt to progressively stop said rotation of the lifting drum occurs after freewheel operation of the lifting drum has commenced.
6 . A device for protecting a lifting member against an overload, said lifting member comprising: a lifting drum on which a lifting cable is wound, cable at the end of which a load is fixed; an electric motor provided with a rotary shaft capable of ensuring a rotation of the lifting drum; a clutch or equivalent device mounted on a mechanical connection connecting the electric motor to the lifting drum and capable of uncoupling the motor from the drum; wherein the clutch or equivalent device is provided with elements capable of ensuring a free rotation of the lifting drum with respect to the rotary shaft of the motor as soon as a torque exerted by the cable on said lifting drum is greater than a predetermined threshold value, called first threshold; wherein the protection device also comprises braking means of the rotation of the lifting drum, the maximum braking capacities of which constitute a second threshold, of a value greater than that corresponding to the nominal load of the lifting member, but of a value less than that of the first threshold.
7 . The device for protecting a lifting member against an overload according to claim 6 , wherein the clutch or equivalent device is constituted of a cartridge, called overload cartridge, which can be coupled respectively to the motor shaft of the electric motor and to the lifting drum, said cartridge being constituted of a dome receiving two rings, independent from one another, but engaging with the other by way of a plurality of balls received in housings of suitable shape provided within one of said rings, and projecting outside of said housings in order to also be received in through-holes provided within the other ring, one of said rings being integral with the dome, itself mechanically connected to the motor shaft of the motor, and the other ring being integral with a means capable of rotating the lifting drum, springs associated with an engagement member with the braking means exerting a pressure on the balls.
8 . The device for protecting a lifting member against an overload according to claim 7 , wherein the housings provided within one of the rings and intended to receive the balls, communicate with an internal annular recess provided within said ring, of depth less than said housings, this communication being made by means of non-radial ramps.
9 . The device for protecting a lifting member against an overload according to claim 7 , wherein the cartridge is removable.
10 . The device for protecting a lifting member against an overload according to claim 6 , wherein the braking means of the rotation of the lifting drum are constituted of friction discs integral with the lifting member, and engaging with a toothed pinion clutched on the axis of rotation of said lifting drum in case of exceeding said first threshold.
11 . The device for protecting a lifting member against an overload according to claim 10 , wherein the braking means are removable.
12 . The device for protecting a lifting member against an overload according to claim 6 , wherein the lifting drum is a capstan associated with a storage drum moved in rotation by an electric motor, and wherein the device further comprises a ratchet wheel activated after exceeding said first threshold, and intended to act on the brakes associated with said storage drum such that said storage drum continues its rotation, in order to preserve a sufficient strain of a cable strand separating the capstan of the storage drum, even in case of operation of the capstan in freewheel mode.
13 . The device for protecting a lifting member against an overload according to claim 6 , wherein the braking means are engaged after commencement of free rotation of the lifting drum.

Description

FIELD OF THE INVENTION The present invention relates to the technical field of lifting members, and more specifically, hoists, and even more specifically, hoists embedded on aircraft and, in particular, helicopters. BACKGROUND A hoist is traditionally constituted of at least one drum, also called lifting drum, associated with kinematics ensuring the rotation of the drum on itself, in order to enable the winding and the unwinding of a lifting cable, at the end of which a load is fixed. One of the problems to which the use of such a hoist conflicts, resides in the safety to be conferred to the hoist and to the associated kinematics, in case of overload. Such an overload can result, in particular when the hoist is embedded on a helicopter, from the fall of an operator connected to the hoist by the cable, from the engagement of the free end of the lifting cable to any fixed point of the shaft, pylon, etc. type. In the absence of a suitable safety device, this occurrence can directly affect the integrity of said operator, and/or the integrity of the helicopter and, in particular, generate their fall with associated dramatic consequences. Such safety devices are known, which induce, in case of detecting the exceeding of a limit load, the unwinding of the cable. These devices traditionally call upon a friction clutch system, constituted of one or more friction discs and a spring, said spring being tared to a value corresponding to the limit mass or limit load beyond which the unwinding of the cable is sought to generate. Doing this, when the limit load is reached, the friction disc(s) no longer adhere(s), for example to the drum, releasing the rotation of it, and consequently, the unwinding of the cable, with, as a first approximation, the absence of friction forces, other than simple friction forces of the axis of the drum on the windings which receive it. Therefore, thus, as long as the load is greater than the taring value of the spring, the kinematic chain is free. However, when the torque being exerted on the drum decreases, in particular below the threshold defined by the taring of the spring(s), the adherence of the friction disc(s), which always exists, returns and makes it possible to dampen, even stop the fall of the load. If such a system makes it possible to ensure a certain protection in case of overload, the implementation of a friction clutch is relatively sensitive and complex, and requires periodic controls, in order to ensure its correct operation according to the limit load that is sought to be imposed on the system. Thus, furthermore, such a system lacks accuracy in terms of triggering threshold, due to the implementation of environmental and operating principle trims, a taring defect of the spring(s) can generate the risk of letting the load fall freely, even not be triggered in case of overload. The control of such springs is therefore determinant to optimize the safety. Moreover, due to the operating mode of such a system, in case of overload, the rupture of the kinematic chain can lead to the complete unwinding of the cable without being able to oppose this. Doing this, such a system has proved to be ineffective for preserving the integrity of an operator connected to the hoist in case of fall, the latter being able to be severely affected at the end position of the unwinding of the cable, resulting from the sudden deceleration of said fall, even in case of impact of said operator with the ground. One of the aims of the present invention is to propose a system which is more reliable in terms of safety, in terms of adjusting the triggering threshold in case of overload and also in terms of modularity of said triggering threshold of the system, according to the operating conditions of the hoist and, consequently, of the helicopter within which said hoist is embedded. SUMMARY OF THE DISCLOSURE To this end, the invention first relates to a method for protecting a lifting member against an overload, the lifting member comprising a lifting drum, over which a cable is wound at the end of which a load is fixed, said drum being mechanically connected to an electric motor, in particular, by a clutch or equivalent device. This method comprises at least two distinct operating thresholds: a first threshold, the exceeding of which generates the freewheel operation of the lifting drum with respect to the kinematic chain coming from the motor;a second threshold, of value greater than that corresponding to the nominal load of the lifting member, but of value less than that of the first threshold, generating the braking of the rotation of the lifting drum and an attempt to progressively stop said rotation of the drum. In other words, and according to a first aspect of the invention, the method first consists of enabling a free rotation of the drum, according to the freewheel principle after the triggering of the first threshold, i.e. when a torque greater than a determined value is exerted on the drum by the