Optical cable

Description

/ 9 OPTICAL CABLE FIELD OF APPLICATION

[001] The present invention relates to a cable for external application in optical distribution and access networks. More specifically, the present invention relates to an optical cable with a single thermoplastic protective tube (loose tube) helically assembled around a metallic tensile element. FUNDAMENTALS OF THE INVENTION

[002] The installation of optical networks, especially in urban environments, represents a challenge to the organization, security, and aesthetics of cities, given that the vast majority of distribution and access networks are installed on overhead infrastructure (poles) due to resources and cost-effectiveness.

[003] From the technical point of view of the optical cables that need to be installed in these environments, there is a growing need for products that generate less visual impact, less weight, less space required, etc. For this, it is necessary that the technology of design, production and application of these cables be reviewed and innovation is an essential factor for this.

[004] Currently there are different product models for this application, cables made up of several loose tubes (multitubes) and cables made up of a single tube (monotubes). However, the single-tube products on the market have limitations regarding diameter, weight, and bending radius, which occur due to the physical limitations of the traction / support element itself. In optical cables, the traction element is generally composed of pultruded FRP (glass fiber reinforced plastic) rods.

[005] Installation using a plastic clamp for cable anchoring is not feasible due to the small bending radius that the clamp imposes on the cable. Furthermore, in most cases, they are classified as aerial cables. Petition 870250007483, dated 01 / 29 / 2025, p. 8 / 23 / 9 self-supporting and the cables for this application do not meet the requirements to also be classified as a "drop" model.

[006] The state of the art includes optical cables with the aim of providing solutions to related problems.

[007] In this regard, document CN213423553 describes an indoor optical cable suitable for pipe wiring, comprising an outer sheath of flame-retardant, halogen-free, low-smoke polyolefin, an annular groove and low-elasticity rubber, two groups of parallel steel wire reinforcing elements are arranged in the outer sheath of flame-retardant, halogen-free, low-smoke polyolefin, a double-sided coated steel and plastic composite belt is arranged on the inner side of the outer sheath of flame-retardant, halogen-free, low-smoke polyolefin, and a double-sided coated steel and plastic composite belt is arranged on the inner side of the outer sheath of flame-retardant, halogen-free, low-smoke polyolefin.The inner side of the double-sided coated steel-plastic composite belt is provided with water-blocking filler paste; the inner side of the water-blocking filler paste is provided with a loose PBT tube; the loose PBT tube is internally provided with a plurality of colored optical fiber groups; the peripheries of the colored optical fibers are filled with thixotropic fiber paste; the outer edge surface of the halogen-free, low-smoke flame-retardant polyolefin outer sheath is provided with an annular groove; and the annular groove is internally filled with low-elasticity rubber. However, document CN213423553 describes a cable that is exclusively internal, with parallel steel elements, for duct applications. Therefore, document CN213423553 does not describe a cable that can be used particularly in aerial applications, such as AS cable and as a drop cable.

[008] Document EP0371660B1 describes an electro-opto cable Petition 870250007483, dated 01 / 29 / 2025, page 9 / 23 / 9 mechanical that includes at least one thin-walled steel alloy tube containing at least one single-mode fiber and a void-filling gel to ensure the ability to transmit low-noise optical phase data. A dielectric ring and an electrically conductive layer disposed within it further help ensure watertight integrity and the transfer of electrical energy or signal. An optional double-layer or three- or four-layer counterhelical steel wire resistance element with torque balance provides additional protection as well as the ability to be towed, deployed, and recovered from the seabed at abyssal depths. The steel armor and cable core interface eliminates all interstitial spaces associated with the armor wires to produce a firm and rigid cable that suffers minimal residual stress (creep) due to extensive load cycling.An extruded pressure outer sheath helps protect individual steel wires against point loads and strength degradation due to corrosion. Document EP0371660B1 describes a cable for various applications, including submarine applications. Therefore, in EP0371660B1, the metallic elements are provided to give pressure resistance, rather than dimensional reduction and expansion of application scope.

[009] Therefore, although there are state-of-the-art solutions related to cables for optical networks, the state of the art lacks a solution capable of addressing all the aforementioned problems. In particular, there is a need for a solution with optimized dimensional constructions, through the reduction of cable diameter and mass. Furthermore, it is necessary to apply it in conditions that require greater flexibility, allowing for smaller bending radii and also anchoring using plastic clamp-type accessories as an alternative to pre-formed accessories. There is also a need for these solutions to comply with regulatory and homologation requirements with the competent bodies. Petition 870250007483, dated 01 / 29 / 2025, p. 10 / 23 / 9 OBJECTIVES OF THE INVENTION

[0010] It is an objective of the present invention to provide an optical cable with equivalent and expanded technical application constructions, by supporting smaller bending radii, enabling smaller overall cable diameter, lower mass, and maintaining compliance with technical requirements such as tensile load, compression, bending, and torsion. SUMMARY OF THE INVENTION

[0011] In order to achieve the above objectives, the present invention relates to an optical cable comprising: one or more optical fibers; a tensile element; and a thermoplastic protective tube configured to accommodate one or more optical fibers, wherein the thermoplastic protective tube is helically braided around the tensile element, wherein the tensile element is metallic. DESCRIPTION OF THE DRAWINGS

[0012] The present invention will be described below, with reference to the accompanying drawings, which are given by way of example only and in which: Figure 1 illustrates a side view according to an embodiment of the present invention.

[0013] Figure 2 illustrates a cross-sectional schematic diagram of an optical cable according to an embodiment of the present invention.

[0014] Figure 3A is a side view of the optical cable to illustrate the helically braided thermoplastic conduit according to an embodiment of the present invention.

[0015] Figure 3B is a longitudinal section of a schematic diagram of the optical cable to illustrate the helically braided thermoplastic conduit according to an embodiment of the present invention. Petition 870250007483, dated 01 / 29 / 2025, p. 11 / 23 / 9 DETAILED DESCRIPTION OF THE INVENTION

[0016] The following description will be based on preferred embodiments of the present invention, as applied to an optical cable comprising: one or more optical fibers; a tensile element; and a thermoplastic protective tube configured to accommodate one or more optical fibers, wherein the thermoplastic protective tube is helically braided around the tensile element, wherein the tensile element is metallic.

[0017] However, as will be evident to a person skilled in the art, the present invention is not limited to the particular embodiments described.

[0018] The present invention relates to optical cables for external installations in optical distribution and access networks, in projects that require products optimized for installations in self-supporting urban networks with spans up to 200 meters. In general, the present invention relates to a single-tube optical cable, optimized for urban subscriber access installations, structured cabling systems for voice, data and image traffic, for distribution networks, for external aerial installation, with direct laying between poles, supporting its own weight, without requiring the use of guy wires, or underground in ducts.

[0019] Figures 1 and 2 illustrate an optical cable according to an embodiment of the present invention. The optical cable (10) comprises one or more optical fibers (1). The optical cable comprises a single thermoplastic protective tube (3) which is configured to accommodate the one or more optical fibers (1). The thermoplastic protective tube (3) is helically braided around a tensile element (5) as also seen in Figures 3A and 3B.

[0020] According to the present invention, the traction element (5) is metallic. The traction element (5) according to the present invention may comprise one or more metallic elements. Preferably, the traction element (5) is made of stainless steel, and may be galvanized, phosphated or Petition 870250007483, dated 01 / 29 / 2025, page 12 / 23 / 9 brass-plated as a traction / support element. The metallic traction element (5), such as a steel wire, has a higher modulus of elasticity compared to FRP and, when used as a traction and support element for the single-tube optical cable, allows, when desired, the classification of the cable as a “drop”, as it will support the tensile loads specified in current requirements for this type of classification.

[0021] Figure 2 shows a cross-section of the optical cable illustrated in Figure 1. As observed in Figure 2, in the cable core, along with the tensile element (5) and the single thermoplastic protective tube (3), is included the moisture protection element (2) for protection against moisture ingress, and a binding element (4) to hold the core together and which may also serve the function of protection against moisture ingress, as it is composed of hydro-expandable material. More specifically, the interior of the thermoplastic protective tube (3) contains one or more moisture protection elements (2) with hydro-expandable material or thixotropic gel filling, for protection against moisture ingress. The entire assembly is covered by an outer sheath (6) made of polymeric material.

[0022] Figure 3A is a side view of the optical cable of the present invention illustrating the thermoplastic protective tube (3) helically braided around the tensile element (5). In addition, Figure 3B is a longitudinal section of Figure 3A to illustrate the interior of the optical cable and the thermoplastic protective tube (3) helically braided around the tensile element (5).

[0023] The present invention, which is a single-tube cable in a circular shape, differs primarily in that the cable has the tube assembled around one (or more) metallic tensile element instead of FRP (Fiberglass Reinforced Pultruded Plastic).

[0024] Cables according to the state of the art, with FRP, Petition 870250007483, dated 01 / 29 / 2025, p. 13 / 23 / 9, allows for a bending radius of up to 22.5 times the diameter of the glass fiber reinforced plastic (FRP) pultruded element (mandrel with a diameter 45 times the diameter of the FRP). The cable according to the present invention allows for even smaller bending radii, no longer limited to the minimum bending radius of the tensile element itself, but limited only to the bending radius limit of the loose tube and the optical fiber.

[0025] The present invention also features a smaller diameter, with cable diameters between 3.0 and 6.0 mm (nominal), which consequently results in a product with less mass, occupying less space in the network, fitting into smaller reels, requiring less storage space, and being easier to handle during installation and maintenance.

[0026] The use of a metallic tensile element, which may be single or multiple, positioned as the central element of the cable, around which the tube containing the optical fibers is helically assembled. The fibers inside the tube may be loose individually within the tube or of the “ribbon” or “rollable ribbon” type, in single or multiple quantities. The metallic tensile element replaces traditional FRPs (multiple or single) in the construction of the ASU cable, allowing for equivalent and expanded technical application constructions, by supporting smaller bending radii, enabling smaller overall cable diameter, lower mass, and maintaining compliance with technical requirements such as tensile load, compression, bending, torsion, etc.

[0027] The present invention solves the problems of the prior art by using one or more metal wire(s) as traction and support element(s). The one or more metal wires can be manufactured from stainless steel, galvanized steel, phosphated steel, brass-plated steel, or with other possible anti-corrosion treatments. Thus, the present invention allows for compaction. Petition 870250007483, dated 01 / 29 / 2025, page 14 / 23 / 9 of the cable assembly, as well as its application in environmental and mechanical conditions that were not previously possible with cables that used FRP (fiberglass reinforced plastic) rod traction elements, where there is a demand for smaller bending radii and resistance to bending.

[0028] The helically arranged loose tube around the metallic tensile element, instead of being arranged in parallel, creates a greater extra length of optical fibers relative to the linear length of the cable, which provides a significant advantage in robustness and optical performance related to the tensile stresses imposed on the cable during and after its installation.

[0029] Thus, the present invention is advantageous insofar as it presents an optical cable that allows miniaturization for application as an aerial cable, without loss of capacity.

[0030] Furthermore, the present invention provides a cable that offers advantages such as space optimization, diameter reduction, mass reduction, greater flexibility, smaller permissible bending radius, and reduced reel size. Consequently, the invention also has the benefit of requiring less storage and transportation space.

[0031] Furthermore, the present invention provides an optical cable that meets the above advantages and also has the possibility of being classified as a “drop” cable.

[0032] With regard to installation, the present invention has the possibility of installation using plastic straps as an anchoring accessory. Furthermore, the present invention also makes it possible to reduce costs in general, but particularly in infrastructure and accessories.

[0033] Although only a few have been presented here Petition 870250007483, dated 01 / 29 / 2025, page 15 / 23 / 9 examples of product embodiments, it should be understood that changes in form and arrangement of the different component parts of the product may be made, without departing from the proposed inventive concept. Petition 870250007483, dated 01 / 29 / 2025, page 16 / 23

Claims

1 / 2 CLAIMS 1. Optical cable (10) comprising: a thermoplastic protective tube (3) configured to accommodate one or more optical fibers (1); characterized in that it further comprises a metallic tensile element (5); wherein the thermoplastic protective tube (3) is helically braided around the metallic tensile element (5).

2. Optical cable (10) according to claim 1, characterized in that the traction element (5) comprises one or more metallic elements.

3. Optical cable (10) according to claim 1 or 2, characterized in that the tensile element (5) is made of stainless steel.

4. Optical cable (10) according to claim 3, characterized in that the traction element (5) is galvanized, phosphated or brass-plated.

5. Optical cable (10) according to any one of claims 1 to 4, characterized in that the thermoplastic protective tube (3) comprises, inside, moisture protection elements (2).

6. Optical cable (10) according to claim 5, characterized in that the moisture protection elements (2) are hydro-expandable materials or thixotropic gel fillings.

7. Optical cable (10) according to any one of claims 1 to 6, characterized in that it further comprises a binding element (4) configured to hold together the core of the optical cable (10).

8. Optical cable (10) according to any one of claims 1 to 7, characterized in that it comprises an outer sheath (6) of polymeric material configured to accommodate the thermoplastic protective tube (3) and the tensile element (5).

9. Optical cable (10) according to any one of claims 1 to 8, characterized in that one or more optical fibers (1) are loosely arranged inside a single thermoplastic protective tube (3) or one or more optical fibers (1) are of the ribbon or rollable ribbon type. Petition 870250007483, dated 29 / 01 / 2025, p. 18 / 23

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