EP0923403B1 - Shock absorbing safety belt - Google Patents

Description

The invention relates to the technical sector of the means of safety to absorb a fall, brake a speed and more generally, absorb energy.

It is known in many applications to use straps acting as a shock absorber to absorb external energy, known as shock absorbing straps (see for example WO 95/01815, GB 2191560 or FR 2709970). For the most part, these straps shock absorbers are composed of two independent layers woven on a determined length and interconnected by interlacing of a chain additional so-called tying in order to constitute a uniform section. The tying chain constitutes a point of connection and rupture during an effort of traction exerted on the free parts of the layers which thus tends to separate the two plies linked against the resistance formed by the wires of woven binding acting as successive shock absorbers until they break.

We can cite for example the teaching of patent FR 2371533 which describes a process for weaving and tying damping straps. according to this process, the binding threads are woven successively with respect to the threads of weft following an irregular tying so that their criss-crossing differs step by step by preventing any sliding at the time of rupture, thus constituting a plurality of groups different. This results in a gradual rupture of each group, at the when the other groups are energized, in order to obtain a regularity of tearing and a slowing down of part of the strap, in relationship with the strength of the tying chain.

This type of shock absorbing strap includes a part, of length determined, that the two layers of yarn are juxtaposed and intimately linked under the conditions indicated described in the patent previously cited, for example. One end of this part where the two layers are intimately linked, presents two unitary strands independent of each other. For example, one of these strands is arranged for be connected to a fixed part, while the other strand is arranged to be connected to a movable part which can move under a given force. If an effort from traction or the like is exerted on at least one of the strands, this results in a tensioning which refers to the level of the tying chain up to the point of rupture between the two intimately linked layers. This results, so concomitant, a successive and continuous tearing of the two linked layers, in acting as energy absorbers and absorbers.

Note also that the other end of the linked part of the two layers, opposite the two free strands connected to the fixed and mobile points, may have two free strands connected to each other, to constitute a safety loop.

Obviously, these safety straps must respond to particular standards. In particular the pulling force between the two intimately linked tablecloths must correspond to numerical values. For get this breakout force, so it's necessary to connect the two tablecloths by means of an additional tying chain having a density of relatively large son, who generally requires to use the loom to weave to the maximum of its capacity. It is therefore not possible, depending on the structure of the woven strap as defined, to decrease the width of the weaving.

The object of the invention is to remedy these drawbacks, in a simple, safe, efficient and rational way.

The problem which the invention proposes to solve is to ability to double the force compared to a standard width of straps tear, or very significantly reduce the width of a strap standard while keeping the same force for this pullout, such than imposed by safety standards.

• une première partie de longueur déterminée où les deux nappes juxtaposées sont intimement liées avec capacité de déchirement sous un effort de traction,
• une deuxième partie, de longueur réduite, où les deux nappes juxtaposées sont libres l'une par rapport à l'autre pour constituer deux brins destinés à être reliés respectivement à un point fixe et à un point mobile ou à deux points mobiles,
• une troisième partie, de longueur déterminée, où les deux nappes juxtaposées sont intimement liées avec capacité de déchirement sous un effort de traction.

To solve such a problem, a shock absorbing strap has been designed and developed consisting of two plies of juxtaposed wires, and having a new structure making it possible to obtain such results. According to the invention, the damping strap successively has:

• a first part of determined length where the two juxtaposed sheets are intimately linked with the ability to tear under a tensile force,
• a second part, of reduced length, where the two juxtaposed plies are free relative to one another to constitute two strands intended to be connected respectively to a fixed point and to a mobile point or to two mobile points,
• a third part, of determined length, where the two juxtaposed sheets are intimately linked with the ability to tear under a tensile force.

In view of these technical provisions, it follows that the tensile or other forces exerted on the two free strands of the strap connected to the fixed and / or mobile points, are distributed in two directions directly opposite and no longer in one direction.

To solve the problem of obtaining depreciation progressive and regular the first and third parts where the layers are juxtaposed are intimately linked, are of equal length.

To solve the problem of obtaining perfect security, especially when the two layers are completely torn under stress of traction undergone, the free ends of the first and third parts do not are not linked to constitute each two free strands connected together so as to form a safety loop.

Given the problem of absorbing energy, the first and third part are intimately linked by means assembly capable of acting as a shock absorber allowing tearing in continuous and progressively, the plies of each of said parts when the strands of the second part are subjected to a tensile force;

Advantageously, the sheets are obtained by weaving. The means of assembling the two layers of the first and third parts are constituted by an additional linkage chain.

La figure 1 est une vue en perspective de la sangle selon les caractéristiques de l'invention.

La figure 2 est une vue à caractère schématique de la sangle en position normale d'utilisation, c'est-à-dire lorsqu'aucune force de traction ou autre n'est exercée sur les brins libres.

La figure 3 est une vue correspondant à la figure 2, montrant le début de déchirement des deux parties juxtaposées et intimement liées de la sangle lorsque les brins libres sont soumis à un effort de traction.

La figure 4 est une vue correspondant à la figure 3, en position de déchirement maximum des deux nappes juxtaposées et intimement liées de la sangle.

The invention is set out below in more detail with the aid of the figures of the appended drawings, in which:

Figure 1 is a perspective view of the strap according to the features of the invention.

Figure 2 is a schematic view of the strap in the normal position of use, that is to say when no tensile or other force is exerted on the free strands.

Figure 3 is a view corresponding to Figure 2, showing the beginning of tearing of the two juxtaposed and intimately linked parts of the strap when the free strands are subjected to a tensile force.

FIG. 4 is a view corresponding to FIG. 3, in the position of maximum tearing of the two juxtaposed and intimately linked plies of the strap.

The shock absorbing safety strap according to the invention is consisting of two layers of juxtaposed wires (1) and (2).

According to a characteristic underlying the invention, the strap has a first part (A) of determined length (L) where the two tablecloths (1) and (2) are juxtaposed and intimately linked with the ability to tearing under a tensile force. Following this first part, the strap has a third part (B) of reduced length and where both tablecloths (1) and (2), juxtaposed are free relative to each other, for constitute two strands (la) and (1b). This second part is extended by a third part (C) of determined length (L) where the two layers juxtaposed (1) and (2) are intimately linked in the same way as for the part (A) with capacity to tear under a tensile force. Strands (la) and (1b) are intended to be connected respectively to a fixed point and at a moving point or at two moving points or even at two points fixed.

The first and third parts (A) and (C) are of length equal (L).

The free ends of parts (A) and (C), opposite the ends where the strands (1a) and (1b) are formed are not linked, for each constitute two free strands (1c) (1d) and (2c) (2d), interconnected by sewing (3) or otherwise, so as to form a safety loop. Parts (A) and (C) are juxtaposed and intimately linked by means assembly capable of acting as shock absorbers, allowing tearing continuously and progressively the plies of each of said parts (A) and (C), when the strands (la) and / or (1b) are subjected to a force of traction (F1) and (F2). For example, when the layers (1) and (2) are obtained by weaving, the means of assembling parts (A) and (C) are constituted by an additional chain of tying.

For example, the binding of the two parts (A) and (C) is carried out according to the technical characteristics defined in patent FR 2,371,533. recalls in this regard that the tying chain threads are fixed successively during the assembly of the sheets and differently by each compared to the others, with regard to the variable strokes of the threads of weft following an irregular tying, so that their intertwining differs longitudinally and transversely, to constitute a plurality of different successive groups allowing a progressive rupture without sliding of each group, when the other groups are under voltage. These provisions allow regular tearing and a slowing of the moving part of the strap, in relation to the resistance of the tying chain.

Obviously and as indicated, we do not exclude other modes of tying the two layers, with the objective of obtaining a progressive tearing of the latter by acting as absorbers of energy, depending on the applied tensile forces and in front meet safety standards. For example, the two tablecloths can be stitched together.

In view of these provisions, it therefore appears that when the two strands (la) and (1b) are subjected for example to two tensile forces (F1) and (F2), the resulting breakout force is distributed, generally by half, at the level of the two parts (A) and (C) and no longer at the level of only a single part presenting the two juxtaposed tablecloths and intimately linked.

These provisions therefore make it possible to double the tensile force exerted on the strands (la) and (1b) while allowing to obtain the same damping effects, compared to a safety strap, depending on the state of the known technique, considered according to the same width, between selvedge.

The specific design of the strap also allows, for the same pulling or tearing force exerted on the strands (1a) and (1b) to produce a strap of reduced width compared to the state of the technical.

In other words, according to the state of the art, a woven strap of safety having only one part where the two plies of son are juxtaposed and closely linked, should be woven across (1) corresponding to the force of pullout criteria dictated by the standards of security. According to the invention, the shock absorbing strap can be woven in a reduced width, always matching the strength criteria safety dictated by safety standards.

The safety strap according to the invention finds numerous applications as well for ensuring braking in a substantially plane vertical than in a substantially horizontal plane, the aim being to absorb a shock after connecting the two strands (la) and (1b) to a structure fixed and / or mobile.

Advantageously, the woven safety strap according to the invention finds application in the safety harnesses used by people. One of the strands (la) is connected in this case, to a fixed part of a structure for example, while the other strand (1b) is connected to part of the harness.

As is perfectly known, the two parts (A) and (C) of the strap are folded to form a compact unit.

The advantages are apparent from the description.

Claims (7)

1. Shock absorbing belt consisting of two juxtaposed yarn laps, having successively:

   a first portion (A) of predetermined length where the two juxtaposed laps (1) and (2) are closely linked with tearing capacity under traction force;

   a second portion (B), of reduced length, where the two juxtaposed laps (1) and (2) are free relative to each other to constitute two sides (la-1b) to be respectively linked to one fixed point and to one mobile point or to two mobile points;

   a third portion (C), of predetermined length, where the two juxtaposed laps are closely linked with tearing capacity under traction force.
2. Belt as claimed in claim 1 characterised in that the first and third portions (A) and (C), in which laps (1) and (2) are juxtaposed and closely linked, are of equal length (L).
3. Belt as claimed in claim 1 characterised in that the free ends of the first and third portions (A) and (C) are not linked so that each portion forms two free sides (lc-2c) and (1d-2d) linked together to form a safety loop.
4. Belt as claimed in claim 1 characterised in that the first and third portions (A) and (C) are closely linked by assembly means capable of acting as a shock absorber by allowing the continuous, progressive tearing of laps (1) and (2) of each of the said portions (A) and (C) when the sides (1a-1b) of the second portion (B) are under traction force;
5. Belt as claimed in claim 1 characterised in that laps (1) and (2) are obtained by weaving.
6. Belt as claimed in claim 5 characterised in that the assembly means of the two laps (1) and (2) of first and third portions (A) and (C) consist of an additional linking warp.
7. Belt as claimed in any of claims 1 to 6 and application thereof to a safety harness.

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