DK2668868T3 - Stiffening element for a backpack and backpack with such a stiffening element - Google Patents

Abstract

The element (1) has an upper section (5), a middle section (10) and a lower portion (15), where the stiffening element is made of regenerating raw material and timber or timber products. The upper section comprises an S-shaped bend (20) and the lower portion comprises a kink (25), where width of the stiffening element is ranged from a specific centimeter to maximum width of a spine portion. A surface of the stiffener element is designed in a smooth manner and provided with wood preservative i.e. linseed oil, to be protected against influences from the weather. An independent claim is also included for a backpack.

Description

Description [0001] The present invention relates to a backpack with a stiffening element. From US 5,320,262 A is already known a backpack having a lattice as stiffening element, which may also be made of wood and is inserted completely into a closable pocket. This document does not show a strip-shaped stiffening element, the surface of which is protected against atmospheric influences by a wood preservative - preferably, linseed oil - wherein the stiffening element engages only in the upper section and the lower section of a slide-in pocket, and the middle section of the stiffening element is visible.

[0002] From DE 199 32 498 A1 is known a stiffening element made of wire that is partially exposed. In its corner regions, the wire-shaped stiffening element has several supporting elements that engage in accommodation chambers. To this end, the stiffening element has, for example, a double-T shape in the corner regions.

[0003] In the prior art, supporting and stiffening elements are known, which serve to stiffen a backpack and, in particular, the back section of a backpack. Basically, embodiments are known in which the backpack is attached to a frame-shaped stiffening element, e.g., in the shape of a back frame with shelf, by additional fastening elements. Stiffening elements that are preferably integrated into the backpack and, in particular, into its back section are, however, also known.

[0004] Such stiffening elements integrated into the backpack are generally made from metal or plastic. An advantage of metal is its high strength, which allows for filigree stiffening elements to be produced. Even though such metallic stiffening elements basically fulfil their function sufficiently, these metallic, and often thin, metal components have sharp edges and corners. In case of movement or loading, the sharp edges and corners result in the covering, which usually consists of flexible fabric, of the backpack possibly being scoured off, cut up, or pierced through. There is, furthermore, a risk of injury to the user.

[0005] As a countermeasure, there is also no possibility of simply forming the stiffening element made of metal to just be thicker and to thus prevent the formation of sharp edges, since the stiffening element would be too heavy and too stiff in this case, as a result of the high specific density of metals. It is consequently necessary to round off the thin corners and edges of stiffening elements by means of upturned edges, such that there is no possibility of damage of the backpack material or injury to the user. The production costs also increase in accordance with the effort needed to subsequently treat the stiffening elements in this way. Another non-negligible aspect is the deformability of metallic stiffening elements as a consequence of the effects of higher loads. Metallic materials, however, do not have a good reputation as to the sustainability of resource use - particularly if the materials are made of lightweight aluminium.

[0006] An alternative variant common today for the production of stiffening elements for backpacks is the use of plastics or composite materials. Compared to metallic stiffening elements, these materials definitely have advantages. For example, they can be produced in almost any shape and have a significantly lower weight. Plastics, also, do not have a good reputation as to the sustainability of resource use and the re-usability at the end of the lifecycle of the backpack, and thus of the stiffening elements integrated into it. In addition to ecological problems, the use of plastics also brings with it mechanical disadvantages. A frequent problem with plastics is the tendency to stress cracking, as a consequence of the loading during use and of inherent stress conditions. The source of inherent stress conditions lies in the production process of the plastic parts - in particular, in the injectionmoulding process. When carrying the backpack, the high loading of the backpack comes from the fact that, while walking, the carrier does not move completely linearly, but, instead, horizontal as well as vertical accelerations occur. Because of the mass inertia of the load carried, these accelerations cause jolts that are transferred to the carrier in a manner reducing comfort. Ideally, a stiffening element reduces these jolts by elastic motions, and thus significantly contributes to the carrying comfort. This, however, also means that the stiffening element is subjected to a continuous load. This continuous load, together with the inherent stress conditions from the production of the stiffening element, can then result in failure of the component, i.e., in fatigue and, ultimately, in breakage of the stiffening element.

[0007] Likewise disadvantageous is the only insufficient resistance of plastics to UV-light irradiation - conditions such as occur with direct solar irradiation, for example. Backpacks are predominantly carried outside closed rooms and are accordingly subjected to high UV- radiation exposure in consequence of their use. In the mountains, a frequent environment of use, the radiation intensity additionally increases due to the thin mountain air. In addition to a colour change, the irradiation of plastics with UV-radiation also results in a change in the mechanical material properties; the plastics become brittle. This also furthers the previously described component fatigue and the later component failure.

[0008] In light of the above, it is the aim of the present invention to provide a backpack with an improved stiffening element that can be produced in a low-cost and resource-saving manner compared to the known stiffening elements and eliminates the mechanical deficits of known devices at the same time.

[0009] This aim is achieved according to the invention by the features of claim 1. Preferred embodiments result from the dependent claims.

[0010] When specifying directions and, in particular, component sections of the subject matter of the invention, terms, such as "at the top" or "at the bottom", are used in the following description of the invention in the manner in which they are defined during a functionally proper use of the subject matter of the invention, i.e., during the carrying of a backpack by a carrier in a vertical orientation.

[0011] According to the invention, the stiffening element is made from wood or wood products, i.e., from a renewable raw material. The use of renewable raw materials for a stiffening element of a backpack contributes to a more resource-saving end product. The disposal or reusability at the end of the lifecycle is also significantly improved when using renewable raw materials.

[0012] According to the invention, the stiffening element is made from wood or wood products. One reason for this is that wood has a high stiffness with a comparatively low density. In addition, wood can permanently transfer repeated bending stress, with only a minor tendency to creep. In the stiffening element according to the invention, the fibres of the wood preferably run parallel to the largest longitudinal extent of the stiffening element. As another reason for the preference for wood, the easy machinability must be mentioned. Particularly advantageous in this case is the use of at least two - preferably, a plurality of - individual wood layers joined to each other. They are preferably joined to each other permanently, using a suitable glue or joiner. A layer count of 5 to 7 laminated wood layers has been shown to be particularly advantageous in this regard. The individual layers preferably have a layer thickness of 1.5 mm.

[0013] The stiffening element preferably has a flat, rectangular cross-section. Stiffening elements with a flat, rectangular cross-section can be carved out of a larger workpiece of the raw material, e.g., by sawing, more easily than cross-sections with other dimensions. In the case of cross-sections with other shapes, e.g., a round or oval shape, another processing step, such as milling or turning, is required after a first cut, in order to achieve the final shape. In the present invention of a stiffening element with a flat, rectangular cross-section, the production costs are consequently reduced.

[0014] According to the invention, the individual large-area, preferably rectangular, wood layers are first placed one above the other, wherein a suitable joiner - in particular, adhesive or glue - is placed between the layers to be joined. The desired permanent joining of the individual layers and the shaping according to the invention take place at the same time in a further step by exerting a planar pressing force on the layered layers - in particular, also by using a thermal component. The specific shaping is in this case realised by using appropriately designed upper and lower pressing parts of the pressing tool. After hardening of the joiner, a planar workpiece formed in the shape according to the invention is produced from the joined, large-area layers. In another step, individual stiffening elements are then separated from the workpiece - preferably, in the form of strips - by means of a sawing device, before the surface treatment and sealing - including a treatment of the edges - of the individual stiffening element take place in a last step. In doing so, the edge is preferably broken at a radius of 4 mm, in order to prevent damage and injury to the backpack material and the carrier respectively.

[0015] Depending upon the type of application, it makes sense that the width of the stiffening element can be from one centimetre up to the maximum width of the back section. Above all, very wide stiffening elements can be used, when only one stiffening element is provided for a backpack. In this case, the width of the stiffening element is limited by the width of the back section. Narrower stiffening elements are used, above all, in backpacks that have several stiffening elements.

[0016] According to an advantageous embodiment, the thickness of the stiffening element is from one millimetre to 30 millimetres. The easy machinability compared to metal stiffening elements and the cross-section of the stiffening element made of renewable raw materials, moreover, allows for the edges and corners to be rounded off in a cost-effective manner, or to be provided with a phase, for example. As a result of the cross-sectional dimensions, it is thus ensured that the material of the backpack on which the stiffening element lies be neither scoured off, cut up, or pierced through. There is also a significantly reduced risk of injury to the user. Depending upon the width and thickness of the stiffening element, its mechanical properties can, moreover, be advantageously changed, and adapted to the requirements.

[0017] Depending upon the type of application, it makes sense that the stiffening element is elastic to differing degrees depending upon the cross-sectional dimensions of the stiffening element, and that the carrying properties of the backpack can thus be adapted to the comfort requirements of the user. The larger the width and thickness of the cross-section are, the stiffer the stiffening element becomes. It can, in general, be established that the stiffening element must be stiffer the heavier the load to be transported in the backpack is-not least in order to prevent breakage of the stiffening element. Because of the specific density of renewable raw materials - in particular, of the preferred material, wood - which is low in comparison to metals, an adaptation of the cross-section of the stiffening element is easily possible, without excessively increasing the weight. In addition to the required stiffness for transferring the load, the stiffening element is elastic to different degrees, depending upon the cross-sectional dimensions. In this way, the carrying properties of the backpack can be adapted to the comfort requirements of the user. In practice, it has been shown that a thickness from one millimetre - in particular, in wide stiffening elements - to a thickness of 30 millimetres - in particular, when using narrow stiffening elements - covers the spectrum of elasticity of the stiffening element of a backpack necessary for the user.

[0018] The spine of the human body has a double-S-shaped curve. The shaping of the present invention is optimised based upon the anatomical shape requirement of the carrier, so that the stiffening element has an upper section, a middle section, and a lower section, wherein the upper section has an S-shaped bend, and the lower section has a kink. The stiffening element shaped in this way brings the backpack into a shape such that its back section follows the course of the double-S-shaped curve of the spine. This significantly increases the carrying comfort. On the one hand, the contact area between the back section and the back of the carrier is increased in this way. Pressure points as a result of point contacts between the back section and the back are thus prevented. On the other hand, the back section can lie closely against the back of the carrier. In this way, it is possible to carry the load in the backpack closer to the body. This results in the centre of gravity of the load not being located as far away from the spine as would be the case with straight stiffening elements with a free space between the back section and the back. The distance between the spine and the centre of gravity of the load in the backpack produces a torque, which must be counteracted by the carrier so that the carrier does not fall backwards. If the distance between the spine and the centre of gravity of the load is reduced, the torque exerted on the body of the carrier is also reduced. This allows the load to be more comfortably carried by the carrier, since the carrier has to counteract a lower load torque. The shaping can easily be achieved using the material according to the invention.

[0019] In order to protect the carrier and extend the lifecycle of the backpack, the surface of the stiffening element is, in an advantageous embodiment, designed to be smooth. By using wood preservatives - preferably, linseed oil - an effective protection against atmospheric influences - in particular, humidity - is ensured. The use of linseed oil has the advantage that the linseed oil layer can, in case of damage to the protective layer or in case of a use-related wear and tear, be renewed at any time by the user rubbing the stiffening element with linseed oil. In contrast to resin-containing products, a coating with linseed oil does not chip off because of the effect of humidity or UV-radiation exposure. Likewise, in case of treatment with linseed oil, no pre-treatment of the surface, e.g., by grinding or the like, need take place. It has proven advantageous that the preferred material wood has a high resistance to UV-radiation. UV-radiation causes only a certain discolouration of the surface, which has, however, no significant influence on the mechanical properties.

[0020] The slide-in pocket is closed on one side and open on the other side. The open side of the slide-in pocket can be opened and closed again using a slide-in pocket closure. A preferred embodiment of the slide-in pocket closure provides for the use of a Velcro fastener. A possible embodiment is the design of the slide-in pocket closure as a tab provided with a Velcro fastener. However, other closures are also conceivable, e.g., using buttons or a zip fastener.

[0021] The ability of the stiffening element to be pulled out of the slide-in pocket and to be replaced by another stiffening element ensures that, after the slide-in pocket closure is opened, the previously described, varyingly hard or stiff stiffening element can be exchanged by the user, without any tool, for another stiffening element, in order to adjust the carrying comfort.

[0022] The invention provides that the slide-in pocket be partially recessed, and that the stiffening element only engage in the slide-in pocket in the upper section and in the lower section, and that the middle section, in particular, of the stiffening element remain visible. In addition to printing a visible identification of the stiffening element onto this visible stiffening element, a carrying device of the backpack may, for example, also be attached to this visible stiffening element. This can, for example, be carried out on the carrying device by means of a tubular pocket that is open on both sides. The tubular pocket in this case surrounds the part of the visible stiffening element.

[0023] Additional features and advantages of the subject matter of the invention result from the following description of specific exemplary embodiments with reference to the figures. The figures show:

Figure 1: a top view of the stiffening element according to the invention;

Figure 2: a lateral view of the stiffening element according to the invention;

Figure 3: the anatomy of a human spine;

Figure 4: a lateral view of the backpack according to the invention;

Figure 5: a simplified view of a back section of a backpack, which is not part of the present invention;

Figure 6: a view of the back section of the backpack according to the invention, with a carrying device;

Figure 7: a perspectival view of a stiffening element according to the invention; and Figure 8: a production method for the stiffening elements, with its individual production steps.

[0024] Figure 1 shows a stiffening element (1) with the three-part division into an upper section (5), a middle section (10), and a lower section (15). The fibre course (A) of the wood is oriented along the longitudinal extent of the stiffening element (1).

[0025] Figure 2 shows a stiffening element (1) with the three-part division into an upper section (5), a middle section (10), and a lower section (15). The upper section (5) has an S-shaped bend (20), the middle section (10) runs linearly, and the lower section (15) has a kink (25).

[0026] Figure 3 shows the anatomy of a spine (65), with the double-S-shaped curve (70). Optimised therefor is the shaping of the stiffening element (1) with an S-shaped bend (20) in the upper section (5), a linearly extending middle section (10), and a kink (25) in the lower section (15). This shaping of the stiffening element (1) results in the back section (45) lying completely against the back of the carrier. In this way, pressure points are avoided, and the load of the backpack (40) is at the same time carried as closely to the body as possible. The torque occurring as a result of the distance between the back and the load is thereby minimised. This is significant with respect to the carrying comfort, since the carrier otherwise has to counteract this torque by exerting force.

[0027] Figure 4 shows a design variant according to the invention of the backpack (40) with the stiffening element (1). In the design variant shown, the backpack (40) has a slide-in pocket (30) that has a recessed section. In the middle section (10), the stiffening element (1) is designed as visible stiffening element (2). In the upper section (5) and in the lower section (15), the stiffening element is inserted into the slide-in pocket (30) and is not visible (3). Another alternative design variant (not shown), which is not part of the present inven- tion, does not provide a recessed section of the slide-in pocket (37). In both design variants, the slide-in pockets (30) have a closed side (31) and an open side (32). The open side (32) of the slide-in pocket (30) is provided with a slide-in pocket closure (35), which can preferably be opened and closed again using a Velcro fastener (36). It is basically insignificant whether the open side (32) and the slide-in pocket closure (35) are located at the top or at the bottom on the slide-in pocket (30). In the design variant shown in figure 4, the open side (32) and the slide-in pocket closure (35) are attached at the bottom, whereas the closed side (31) of the slide-in pocket (30) is at the top. Also conceivable is a third design variant with slide-in pocket closures (35) at two opposite open sides (32) of the slide-in pocket (30).

[0028] Figure 4 shows a backpack (40) with a carrying device (50). In the recessed section of the slide-in pocket (37), the visible stiffening element (2) is passed through a tubular pocket (60) attached to the carrying device (50), and the carrying device (50) is thus attached to the back section (45).

[0029] Figure 5 shows the back section (45) of a design variant with two stiffening elements (1) and slide-in pockets (30), which are not part of the present invention. However, deviating from the design variant shown, other design variants (not shown) with only one stiffening element (1) or more than two stiffening elements (1) are also conceivable, which are part of the present invention if they fall within the scope of the set of claims. For purposes of better visibility, the carrying device (50) is not shown in figure 5. In the design variant shown, the slide-in pocket (30) is not recessed. The closed side (31) is located at the top on the back section (45), and the open side (32), together with the slide-in pocket closure (35), is located at the bottom. Not shown here are design variants with an open side (32) and a slide-in pocket closure (35) at the top on the back section (45) or design variants with two open sides (32) and two slide-in pocket closures (35) at the top and at the bottom on the back section (45).

[0030] Figure 6 shows the complete back section (45) with the carrying device (50) of a backpack (40) with covering (55), as well as an additional hip belt (53) and visible stiffening elements (2). The non-visible stiffening elements (3) are located in the slide-in pocket (30). In the variant shown, two stiffening elements (1) are used.

[0031] Figure 7 shows a stiffening element (1) in the preferred design variant made from wood, as well as the latter's fibre course (A), which extends along the longitudinal extent of the stiffening element.

[0032] The production method according to the invention of the stiffening elements 1 with its individual production steps is shown in figure 8. The individual large-area and rectangular wood layers are first placed one above the other, wherein a suitable adhesive or glue is placed between the layers to be joined. The desired permanent joining of the individual layers and the shaping according to the invention take place at the same time in another step by exerting a planar pressing force on the layered layers. The specific shaping in side profile - the upper section 5 has the S-shaped bend 20, while the middle section 10 extends linearly, and the lower section 15 has a kink 25 - is in this case realised by using appropriately designed upper and lower pressing parts of the pressing tool. After hardening of the joiner, a planar workpiece formed in the shape according to the invention is produced from the joined, large-area layers. In a further step, individual stiffening elements 1 are then separated from the workpiece in the form of strips by means of a sawing device. In a last step (not shown), the surface treatment and sealing - including a treatment of the edges - of the individual stiffening element 1 takes place.

List of reference symbols [0033] 1 stiffening element 2 visible stiffening element 3 non-visible stiffening element 5 upper section 10 middle section 15 lower section 20 S-shaped bend 25 kink 30 slide-in pocket 31 closed side 32 open side 35 slide-in pocket closure 36

Velcro fastener 37 recessed section of the slide-in pocket 40 backpack 45 back section 50 carrying device 53 hip belt 55 covering 60 tubular pocket 65 spine 70

double-S-shaped curve A fibre course

Claims (6)

A backpack (40) having a back portion (45) and a stiffening element (1), wherein the stiffening element (1) is made of wood or wood products, the stiffening element (1) is strip-like and has an upper section (5), a middle section ( 10) and a lower section (15), the upper section (5) having an S-shaped bend and the lower section (15) having a jaw, the backpack (40) of the back portion (45) comprising an insertion pocket (30) and the stiffening element (1) can be accommodated in the insertion pocket (30), characterized in that the surface of the stiffening element (1) is protected against weather with a wood preservative, preferably linseed oil, and the insertion pocket (30) is partially recessed, and the stiffening element (1) only in the upper section (5) and in the lower section (15) engage the insertion pocket (30) and the middle section (10) of the stiffening element (1) can be seen. Backpack (40) according to one of the preceding claims, characterized in that the stiffening element (1) has a flat square cross-section. Backpack (40) according to one of the preceding claims, characterized in that the width of the stiffening element (1) can be from one centimeter to the maximum width of the back portion (45). Backpack (40) according to one of the preceding claims, characterized in that the thickness of the stiffening element (1) can be from one millimeter to 30 millimeters. Backpack (40) according to one of the preceding claims, characterized in that the surface of the stiffening element (1) is smoothly formed. Backpack (40) according to claim 1, characterized in that the insertion pocket (30) is provided with an insertion pocket closure, preferably designed as a Velcro closure, so that the insertion pocket (30) can be opened and closed.