LOAD STRETCHER SYSTEM

The invention relates to a load bearing system comprising a load bearing textile strap.

The invention will find useful applications anywhere where a load needs to be spread along a contacting surface. Such useful applications will include objects which are supposed to come in contact with a portion of the body of the user of such object, such as: climbing harnesses, backpack shoulder straps, backpack hip belts, ski pole straps, medical slings, car seat belts, bag carrying straps, etc....

Currently, in such applications, a cushion pad may be provided adjacent the strap, so that the cushion pad is interposed between the strap and the user's body in order to avoid direct contact. The cushion pad is sometimes wider that the load bearing strap, but, usually by only a small amount. Moreover, the cushion pad being basically soft, it has a significant load spreading effect only very close to the edges of the strap. Therefore, the load is not properly spread and may result in too much contact pressure on the body, causing undesirable effects.

The invention may also be useful in other categories of applications, like for example in industrial lifting slings. Indeed, in such applications, it may also be desirable to increase the load spreading effect between the load bearing system and the object which it comes in contact with.

In order to achieve better spreading of the load, it is known to use variable width textile straps. Such straps are woven in a specific way at predefined positions along their length, most of the time by modifying the weaving parameters in a specific section of the strap. Typically, such techniques allow to increase the width of the strap at those specific predefined locations up to double the nominal width of the strap, but not more. Such techniques increase the production cost of the strap and they show no flexibility: once the strap is woven, the location, shape and measurements of the portions of increased width cannot be adjusted to each specific application.

Such variable width straps do achieve a load spreading effect, but it is limited by the maximum width increasing ratio. Other constraints include having to weave a specific strap for each individual application.

It is therefore an objective of the invention to provide a new construction for a load bearing systems which achieves a desired load spreading effect in an easy, flexible, low-cost and effective way.

In view of this objective, the invention provides for a load bearing system comprising a load bearing textile strap, wherein said strap comprises a woven portion having warp yarns extending along a longitudinal direction of the strap interlaced with at least one weft yarn, wherein said woven portion of the strap has a first width, wherein said strap has a non-woven portion comprising only at least a part of said warp yarns, and wherein, in said non-woven portion, said warp yarns are spread transversally so as to spread over a second width greater that said first width of said woven portion.

Other aspects of the invention will be set forth in the following detailed specification which refers to the appended drawings in which:

• Figure 1 is a schematic view of one example of a conventional woven strap;
• Figure 2 is a schematic view of the strap of Figure 1 where, in an intermediate portion of the strap, the weft yarn(s) has (have) been removed, forming an intermediate non-woven portion;
• Figure 3 is a schematic view of the strap of Figure 2 where, in the intermediate non-woven portion, the warp yarns have been spread transversally;
• Figure 4 is a schematic perspective view of the strap of Figure 3 showing how the warp yarns of said non-woven portion may be adhesively bonded on a support surface;
• Figure 5 and 6 are schematic drawings showing a simple and economical process for removing the weft yarn(s) in a portion of a conventional woven strap;
• Figure 7 is a schematic perspective view of another embodiment of the invention where the non woven portion is an end position of the strap, and;
• Figure 8 is a schematic perspective view of a climbing harness equipped with a load-bearing system according to the invention.

On figure 1 is shown very schematically a woven strap 10. Basically it comprises a series of warp textile yarns 12 which all extend substantially parallel one to another along the longitudinal direction of the strap. As in any woven textile, at least one weft textile yarn 14 is provided which is interlaced with the warp yarns 12, in that it extends transversally back and forth across the width of the strap, passing over some of the warp yarns and under other warp yarns. It is well known that diverse weaving patterns can be used (plain weave, twill weave, satin weave, etc...), each of them having all sorts of possible variations and elaborations. The strap could also be woven with several weft yarns. In each case though, the weft yarn(s) 14 is (are) continuous and, when it reaches the edge of the series of warp yarn, it turns back in the opposite transverse direction, again being interlaced with the warp yarns 12.

The diagrammatic aspect of Figure 1 does not show that, in a woven strap, the warp and weft yarns are preferably tightly woven so that in fact non void space is visible between the yarns. Moreover, with certain weaving patterns, a strap can be made which seemingly exhibits several superimposed layers of warp yarns, the layers being interconnected or not by the weft yarn. It also know to have a special weaving/knitting of the weft and warp yarns along the edges of the strap, mainly in order to provide an additional locking effect of the weft yarn on the edge warp yarns. Such locking ensures that the strap does not unravel totally if the weft yarn brakes at one point of the strap. In the drawings, the warp and weft yarns appear to be of the same nature and size, but it is of course common to use different warp and weft yarns, and also to use different warp yarns along the width of the strap, for example using stronger warp yarns along the edges of the strap.

The woven portion of the strap had a fist width. Although that first width could vary along the length of the woven portion (as known in the prior art), the first width is substantially constant along the length of the non-woven portion.

According to one aspect of the invention, it is provided a strap 10 having a portion where the weft yarn is absent, that is a non-woven portion 16.

In the example shown on Figure 2, the non-woven portion is an intermediate portion of the strap between two woven portions 18, 20. In the example shown, the non woven portion16 of the strap has only warp yarns 12 extending along the longitudinal direction of the strap 10. Those warp yarns 12 are continuous with the warp yarns 12 of the two woven portions 18, 20 adjacent the non-woven portion. In the example shown, all the warp yarns of both woven portions are continuous through the non-woven portion. Nevertheless, it could be chosen that only a portion of the warp yarns 12 of those woven portions 18, 20 are continued through the non woven portion 16.

Such non-woven portion 16 could be made simply by interrupting the weaving process, namely by interrupting the interlacing of the weft yarn(s) with the warp yarns on the weaving loom, while letting the warp yarns advance through the loom. Therefore, after a first upstream woven portion 18 has been woven, the weaving process would be interrupted for a period of time corresponding to the time necessary for the desired length of the non-woven portion to advance through the loom. Then, the weaving process would resume in order to weave the adjacent downstream woven portion 20. A strap 10 with a built-in non-woven intermediate portion 16 could therefore be directly produced in such way.

In figures 5 and 6 is shown an alternative and very simple method to make a non-woven portion 16 in an initially continuously woven strap as shown in Figure 1. The idea is simply to remove the weft yarn(s) 14 in the desired portion of the strap. In order to do so, it is sufficient to cut the weft yarn(s) 14 along one of the edges of the woven strap 10. As shown on figures 5 and 6, if a weft yarn 14 is cut a two of its consecutive turn back locations at the edge of the strap 10, then the weft yarn forms, between the two cut-outs, something like a "U pin" with only the branches interlaced with the warp yarns. That "U pin" is virtually not locked any more to the warp yarn and can be easily pulled out. If the strap has been woven with an additional special locking effect along the edges of the strap (as discussed above), the locking weave/knit usually involves only one or a few warp yarns along each edge of the strap, and for commodity, it may be simpler to cut also those warp yarns at each of the longitudinal ends of the desired non-woven portions and to remove them together with the weft yam(s).

The main advantage of this process is that it is possible to use almost any standard strap, so that the strap can be sourced in great quantities for a variety of applications. Indeed, with a given standard strap, it is very easy to adjust the length and position of the non-woven portion(s) relative to the length and position of the woven portions, keeping full flexibility in the choice of the base strap depending on the application. To the contrary, a ready-made strap with built-in non-woven portions will not exhibit such flexibility.

The cutting of the weft yarn(s) may be done manually, as indicated in Figure 5, for example with scissors or with a blade, or it can be done with a specific tool, for example a die-cut, or even with a machine like a laser cutting machine. Manual operations will be of course more flexible, the exact length and position of the non woven portion being easily determined by the precise location of the cutting. Operations done with a specific tool or machines will be more productive, while requiring some preparation.

As can be seen in Figures 3 and 4, the warp fibres of the non woven-portion of the strap can be spread transversally and maintained transversally spread apart.

Various techniques can be used to maintain the warp yarns in the spread apart configuration.

One method would be to make a series of transverse stitches to stitch down the warp yarns 12 on a support surface. Such support surface could be any kind of textile material, of laminate material, of film, etc...

But, according to an optional aspect of the invention, the warp yarns 12 may be very effectively maintained in their spread apart configuration by adhesive bonding.

Depending on the materials making up the yarns, different adhesive bonding techniques can be used. It is within the scope of the invention that, if the materials are compatible, one can envision that the yarns be affixed on a support surface by welding, for example ultrasonic or radio-frequency welding. But, in most cases, the adhesive bonding preferably will be achieved through the use of adhesive materials such as glues or glue-containing compounds. Many types of glues can be used, such as, for example, polyurethane based glues. Those glues can be in the form of self-standing films or in liquid form. They can be thermo-activated glues, e.g., hot-melt glues. A glue-containing compound may be for example made of two or more films of hot-melt adhesive, possibly of different compositions to adapt to the specific materials of the warp yarns on one side and of a support surface on the other side. The gluing compound could also possibly have an interfacial layer between two adhesive films. The interfacial layer could for example be a fabric layer or a foam layer.

In the example shown, the adhesive bonding is achieved though the use of a self-standing film of thermo-activated polyurethane glue 22. The film is for example pre-cut to a desired shape (which here corresponds to the shape of the non-woven portion 16 of the strap 10 and its spread apart warp yarns 12) and simply heat pressed on the strap. In doing so, the glue will flow very intimately around each yarn and secure each yarn very solidly. Indeed, contrary to a tightly woven web where the tight interlacing might prevent the glue from perfectly bonding to the fibres (unless a perfect match of temperature, glue flow rate and glue quantity is achieved), it will be relatively easily to secure a perfect bonding of the yarns.

As shown in Figure 4, it is possible to provide that the non-woven portion 16 be sandwiched between two films of hot-melt glue 22.

In any case, it is desirable that the film(s) of glue has (have) a length greater than the length of the non-woven portion in order to cover not only the non-woven portion 16 but also the neighbouring parts 17, 19 of the woven portions 18, 20. Indeed, the film of glue will therefore not only maintain the warp yarns 12 in a spread apart configuration, but will also prevent the terminal transversal edges of the woven portions 18, 20 from fraying.

The strap therefore exhibits a load spreading portion of having an increased second width compared to the first width of the woven portion. The load spreading portion is made without compromising the amount of load that the strap can withstand since the warp yarns 12, which bear most of the load, are continuous through both woven portions 18, 20 and through the non-woven portion 16.

The strap and its load spreading portion can be totally or partially encased in a flexible casing or envelope, made for example of two sheets of textile material joined along their edges. The load spreading portions of the strap will preferably be glued inside the casing.

Adjacent the load spreading portion of the strap, it is possible to provide a cushioning layer, for example a foam layer. The cushioning layer may be glued onto the load spreading portion. In case the load spreading portion is encased in a casing, the cushioning layer may for example be contained within the casing.

The embodiment described above has a non-woven portion in an intermediate location between two woven portions of the strap.

In Figure 7 is shown the case where the non-woven portion is an end portion of the strap, which end portion is to be connected to a support surface 24 in order to transfer the load to said support surface 24.

Such an embodiment can be used for example when connecting a load bearing strap to a backpack waist-belt, etc.

Here, it can be seen that the warp yarns 12 of the non-woven portions have free ends (not connected to another woven portion), so that they can be spread angularly apart as in a fan. As discussed above, this fanned end portion can be glued on the support surface 24 via any of the techniques described above (for example by using a thermo-activated sheet of glue, or simply by stitching), and it can also be covered by a covering layer 26, which itself can be glued on with another sheet of glue 22.

In Figure 8 is shown an exemplary application of the invention, with the load bearing system being integrated in a climbing harness 30. The climbing harness 30 has for example a waist belt 23 and two leg loops 34. The waist belt 32 and the two legs loops 34 each have a rear comfort part 36, 38 of greater width which is intended to transfer most of the contact pressure between the harness 30 and the corresponding parts of the user's body, respectively the lumbar part of the back and the back of the thighs.

A securing ring 40 is secured on the front part of the waist belt and a link strap 42 connects the two legs loops 34 while passing through the securing ring 42.

As can be seen on figure 8, the waist belt 32 comprises a load bearing system according to the invention. A load bearing textile strap 10 encircles the waist of the user and is closed on itself in an adjustable manner through an adjustment buckle 44. According to the invention, the strap 10 is a woven strap having a non woven portion 16. Advantageously, the non woven portion 16 is located in the rear comfort zone 36 of the waist belt 32, in order to give it its enlarged width. In the example shown, the non woven portion 16 of the strap is encased in a textile casing 46 (partially cut-out in the drawing to show the non woven portion of the strap). The front part of the strap, and especially the connecting zone where the adjustment buckle 44 is located, is made up of two woven portions 18 of the strap 10.

The two leg loops 34 are constructed in a similar way with a load bearing strap 10 which is closed on itself (here in a non-adjustable manner, for example through adequate sewing of the two woven extremities of the strap), the strap having a non-woven back portion 16 (also encased in a supple casing 46) intended to come in contact with the back of the user's thighs.

A climbing harness constructed as above is extremely light in weight while remaining comfortable to wear, thanks to the load spreading effect of the non-woven portion of the strap.

Of course many variations can be devised in the use of the load bearing system according to the invention in a climbing harness. For example, only the waist belt or only the leg loops could be built using a load bearing system according to the invention.

Other uses of the invention are contemplated for making various articles such as: backpack shoulder straps and hip belts, industrial lifting slings, ski pole straps, gear slings, gun straps, musical instrument straps, medical slings, etc...