Load-bearing elements for a conveying system, in particular carrying belts for elevators

Abstract

Supporting element for a conveying device, in particular a carrying belt (1) for elevators, which has tensile or stress members, each of which is designed as a bundle or package (2, 3) of interconnected fibers, characterized in that the individual fiber bundles or packages (2, 3) have in cross-section such a layering of different fibers (4, 5) or fiber materials that the outer fiber layers (4) of the fiber bundles or packages with respect to the bending radius under load have a greater permissible elongation than the corresponding inner fiber layers (5), wherein the fiber bundles (2, 3) are designed as flat fiber packages which have a significantly greater width than thickness and the layering of different fibers or fiber materials takes place over the thickness of the fiber packages.

Description

[0001] The invention relates to a support element for a conveying device, in particular a carrying belt for elevators, which has tensile or reinforcing elements, each of which is designed as a bundle or package of interconnected fibers.

[0002] WO 2009 / 090 299 A1 discloses a flat-shaped support element or a support belt for an elevator, which has a significantly greater width than thickness and includes reinforcing elements, i.e., tensile or strengthening elements or cords for absorbing the tensile forces, which have carbon or glass fibers enclosed by a polymer matrix.

[0003] The fibers can be arranged parallel and evenly distributed along the longitudinal direction of the load-bearing element, or as interconnected bundles of fibers, see e.g. Fig. 1a to 1e of WO 2009 / 090 299 A1, wherein the individual fiber bundles or packets are formed in cross-section approximately in the form of a flat band or packet.

[0004] The individual fiber bundles or packages are adapted to the cross-section of the support cable or belt in such a way that one or more flat fiber bundles are arranged distributed across the width of the belt. This achieves a high load-bearing capacity with low weight and prevents relative movement of the fibers against each other, thus avoiding excessive internal friction.

[0005] One disadvantage of this design is that when these support elements are bent over a defined diameter, high elongations naturally occur in the outer areas of the bending radius and thus in the outer fibers of the support element bundles or packages.

[0006] The thickness of the bundles is thus limited by the maximum permissible tensile stress of the fibers. The tensile strength of the load-bearing element, which is primarily determined by the thickness, width, and number of fiber bundles, therefore reaches its design limits and cannot be altered by increasing the thickness of the load-bearing element for a given roller or bending diameter and a given load-bearing element width.

[0007] Similar disadvantages arise for the subject matter of the invention of EP 1 640 307 A2. EP 1 640 307 A2 also discloses lifting belts, which, among other features, have the characteristic that reinforcing elements or tensile members made of aramid are arranged in a flat load-bearing element with a width greater than thickness (width = w, thickness = t, w / t > 1) in the form of flat bundles or packages distributed across the width of the belt. The bundles or packages can be enclosed in a common casing, which is intended to optimize the transmission of shear forces. The aramid fibers used here are less suitable for certain applications with regard to their tensile strength and temperature resistance.

[0008] The object of the invention was therefore to provide a load-bearing device, in particular a flat support belt, in which, for a given width of the support belt and given roller diameters, the load-bearing capacity is increased compared to the prior art, without a significant increase in the weight of the support belt and with the same simple manufacturing process.

[0009] This problem is solved by the features of the main claim. Further advantageous embodiments are disclosed in the dependent claims.

[0010] The individual fiber bundles or packages exhibit a cross-sectional layering of different fibers or fiber materials such that the outer fiber layers of the fiber bundles or packages, relative to the bending radius under load, have a greater permissible elongation than the corresponding inner fiber layers. This layering design according to the invention allows the composite to be guided over rollers with a relatively small diameter and the support belt to be bent relatively sharply without causing damage to the outer fibers of the support bundles or packages due to exceeding the permissible elongations or tensile stresses. The additional and different fiber layers, namely the introduction of additional fibers with high elongation tolerance on the outer bending surface, significantly increase the tensile strength of the overall composite in this type of sandwich construction.

[0011] An advantageous further development involves forming the fiber bundles as flat fiber packages that are significantly wider than they are thick, with the layering of different fibers or fiber materials occurring across the thickness of the fiber packages. This results in particularly simple manufacturing and a flat, high-load-bearing conveyor belt for elevators, which can nevertheless be easily operated even with small rollers and tight bending radii.

[0012] Another advantageous design involves distributing several fiber bundles or packages across the width of the load-bearing element. This distribution can be uniform or uneven, for example, of ribbon-shaped fiber bundles or packages. The fiber bundles or packages can also have different cross-sectional shapes, such as round or rectangular. This allows for excellent adaptation of the load-bearing capacities and weights of the belts to the specific application. Consequently, the tensile strength is increased for the same width and bending radius.

[0013] Another advantageous design feature is that the outer fiber layers, relative to the bending radius under load, consist of aramid fibers, while the corresponding inner fiber layers consist of carbon fibers. While carbon fibers exhibit elongation at break of approximately 1.5%, the elongation at break of aramids can reach up to 4%. A similar ratio is thus achieved for the permissible elongations under load when bending around a conveyor pulley of an elevator. Therefore, by selecting suitable materials, the tensile strength of the conveyor belt can be optimized to achieve the required elongations of the cords, resulting in high load-bearing capacity combined with high bending stress.

[0014] A further advantageous embodiment consists in the outer fiber layers, relative to the bending radius under load, comprising fibers made of polyphenylene-2,6-benzobisoxazole (PBO, trade name Zylon). PBO fibers are high-strength and at the same time extremely ductile, and therefore ideally suited for the application according to the invention. The same applies to high-modulus polyethylene (HMPE), aramid, or liquid crystal polymer (LCP), which are also suitable as outer fiber layers. Carbon fibers, glass fibers, or basalt fibers are suitable as inner fiber layers.

[0015] While parallel fibers are typically used in the fiber bundles, a further advantageous design involves the fiber bundles or packages having at least partially twisted / laid fibers. This further increases the cord strength and thus the load-bearing capacity of the support belts.

[0016] The invention will be explained in more detail using an exemplary embodiment. The single figure ( Fig. 1) shows a carrying belt for elevators which has tensile or reinforcing elements in the form of embedded cords, each formed as a bundle or package of interconnected fibers.

[0017] In the Fig. Figure 1 shows part of a longitudinal section of a carrying strap 1, in the upper part of the Fig. 1 in a stretched position and in the lower part of the Fig. 1 in a position during a bend under load around a deflection pulley not shown in detail here.

[0018] The individual fiber bundles or packages 2, 3 exhibit in cross-section, and thus also in the longitudinal section shown here, a layering of different fibers or a layering of fibers 4, 5 of different fiber materials, so that a kind of sandwich structure is created in which the fiber bundle consists of several strands of different individual filaments laid on top of each other.

[0019] With regard to the bending radius under load, the outer fiber layers of the fiber bundles or packages exhibit a greater permissible elongation than the corresponding inner fiber layers. In the Fig. 1. The support belt has two strands consisting of parallel individual fibers, designated as fiber bundles 2 and 3, of which strand / bundle 2 on the outer side of the bend consists of aramid fibers with a permissible material elongation of 2%, while strand / bundle 3 on the inner side of the bend consists of carbon fibers with a permissible material elongation of 1%. In the lower part of the Fig. Figure 1 shows that during bending under load around a deflection pulley (not shown in detail here), the resulting strains correspond to the permissible strains in the fibers. The upper layers have a greater permissible strain than the base layer, so this composite of matched fibers can be bent over the same diameter without risk of overstretching. The possibility of increasing the number of fibers by adding fiber layers of different materials naturally also significantly increases the tensile strength of the overall composite.

[0020] The cross-sectional shape of the fiber strands / fiber bundles is not shown. The latter are oriented perpendicular to the direction in Fig. 1 shown in the sectional view (cross-section) are designed as flat fiber packages that have a significantly greater width than thickness and are evenly distributed across the width of the load-bearing element. Reference symbol list 1 carrying strap 2 fiber bundles or packages 3 fiber bundles or packages 4 strands of parallel aramid fibers 5 strands of parallel carbon fibers

Claims

[1] Support element for a conveying device, in particular a carrying belt (1) for lifts, which has tensile or stiffening elements, each of which is formed as a bundle or package (2, 3) of interconnected fibers, characterized by , that the individual fiber bundles or packages (2, 3) have in cross-section such a layering of different fibers (4, 5) or fiber materials that the outer fiber layers (4) of the fiber bundles or packages have a greater permissible elongation with respect to the bending radius under load than the corresponding inner fiber layers (5), wherein the fiber bundles (2, 3) are designed as flat fiber packages which have a significantly greater width than thickness and the layering of different fibers or fiber materials is carried out over the thickness of the fiber packages. [2] Supporting means according to claim 1, in which several fiber bundles or fiber packages (2, 3) are arranged distributed over the width of the supporting means. [3] Supporting device according to claim 1 or 2, wherein the outer fiber layers (4) with respect to the bending radius under load comprise aramid fibers and the corresponding inner fiber layers (5) comprise carbon fibers. [4] Supporting device according to any one of claims 1 to 3, wherein the outer fiber layers (4) with respect to the bending radius under load comprise fibers made of polyphenylene-2,6-benzobisoxazole (PBO). [5] Supporting means according to any one of claims 1 to 4, wherein fiber bundles or packages (2, 3) comprise at least partially twisted and / or twisted fibers or fiber yarns. [6] Elevator with at least one support element according to one of claims 1 to 5, wherein each support element has at least one fiber bundle or package consisting of at least two layers or layers of different fibers or fiber materials, wherein the width of the layers is greater than their thickness, preferably twice as wide as the thickness of the layers.

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