SE532329C2 - Optical indoor fiber cable - Google Patents

Description

The belt comprises at least one optical fiber, at least one strain relief and an outer sheath which tightly encloses the optical fiber and the strain relief, the optical fiber and the strain relief being twisted together.

The fibers designed in this case have an optimal structure, which results in good blowing, feed-in and tensile properties, with improved installation performance.

According to a further embodiment, the optical fiber and the strain relief are located so that the corresponding longitudinal axes thereby do not coincide with the central axis of the cable.

According to a preferred embodiment, the cable comprises two optical cables and two strain reliefs.

This type of configuration involves a cable with an optimal dimension and rigidity structure.

According to another preferred embodiment, the strain relief is a glass-reinforced plastic rod.

According to yet another embodiment, the outer jacket comprises a halogen-free fire-resistant material.

According to a further embodiment, the optical fiber is enclosed by an outer coating.

The outer coating mechanically protects the optical fiber and results in easy and safe coupling of the optical fiber.

According to another embodiment, the optical fiber cable comprises a water-swellable material in the cavity of the cable.

The water-swellable material is intended to protect the optical fiber cable from the ingress of water and thus enables reduced water exposure.

According to yet another embodiment, the outer sheath comprises silicone additives.

This improves the installation lengths because the friction between the cable and the protective pipe is reduced, which means a low coefficient of friction for the outer sheath.

According to another preferred embodiment, the diameter of the cable is less than 6 mm.

The smaller diameter preferably increases the potential installation distance and installation in protective pipes with smaller diameters is possible, ie micro-protective pipes.

Consequently, it enables telecom operators to design more flexible networks. Yet another object of the invention relates to the use of the cable in feed-in drawing or blowing installations.

The cable thus means a versatile structure, which is preferably used in different types of indoor installations, ie feed, pull or blow installations. Other features and advantages of the invention are further described in more detail in the following description, which does not constitute a limitation in any respect, in connection with the drawing, in which Fig. 1 is a cross-sectional view of an optical erk berkabei according to the invention. .

Fig. 1 shows a preferred embodiment regarding the optical fiber cable according to the invention.

The optical fiber cable 1 comprises in the form of examples two optical fibers 2 and two strain reliefs such as e.g. glass reinforced plastic (GRP) rods 3.

The optical fibers and rods are held by the outer sheath 4 by enclosure.

The optical fibers and rods are twisted together, which makes it possible to obtain a cable 1 with a reduced diameter and an optimum rigidity.

The twisting is made possible in a helical direction with the designation "S" or "Z" twisting or beating with reversed, oscillating twisting with the designation "S-Z" twisting or any other form of twisting configuration.

The optical fiber according to the invention may consist of optical fiber in simple form, e.g. lTU-T Recommendation G.652.D optical fiber or multimodal optical cable. .ex. lTU-T Re- commendation G.651 optical fiber.

This exemplified lTU-T G.652.D optical fiber is in principle composed of a glass core with a diameter of 9 μm, which is enclosed by a glass coating with an outer diameter of 125 μm.

The optical fiber comprises at least one layer of UV-curable polymer composition, which encloses the coating, the outer diameter of the coating amounting to about 250 μm.

According to a preferred embodiment of the invention, the optical fiber 2 is enclosed by an outer coating 5, derived from an extruded polymer or UV-cured polymer. on the basis of examples, the extruded polymer is derived from the polymer Hytrel, supplier DuPont.

The present outer coating 5 mechanically protects the optical fiber and results in a simple and safe coupling of the optical fiber. optical fiber 2 in common with the outer coating 5 identical diameter resp. rod 3, especially the diameter 900 pm.

According to this example, the nominal thickness of the outer coating 5 is about 650 μm.

Thus, a symmetrical cable is made possible, which maintains a structure with a round shape with a basically circular cross-section.

On the basis of a preferred embodiment according to fi g. 1, the fiber and rods with an alternative configuration for limiting the preferred bending directions of the cable are preferably placed. 10 15 20 25 30 532 329 4 Thus, each outer coating 5 is in direct contact with two rods 3 and resp. rod 3 is in direct cash with two outer coatings 5.

In addition, according to Fig. 1, only resp. optical fi ber 2 and GRP rod 3 located separately from the central shaft to the cable network, ie no additional optical fiber or strain relief is coaxially located in connection with the central shaft of the cable.

According to a preferred feature of the present invention, the outer jacket 4 preferably comprises any suitable polymer known in the prior art for the production of a halogen-free, refractory material (HFFR).

The outer jacket is produced e.g. on the basis of an extruded composition comprising a copolymer of low density polyethylene and ethyl vinyl acetate (LDPE-EVA) and a flame retardant filler.

The flame retardant filler may be a metal hydroxide, preferably magnesium hydroxide.

The nominal thickness of the outer jacket 4 is e.g. 800 um.

Thus, on the basis of the diameters of the glass core, the glass coating, the UV-curable layer, the outer coating, the GRP rod and the thickness of the outer sheath, all diameters being exemplified, the diameter of the optical cable is about 4 mm.

The optical carrier cable 1 may comprise water-swellable material, which is located in the cavity of the cable, ie the inner empty space in the cable.

On the basis of Fig. 1, the water-swellable material originates e.g. from water-swellable threads 6.

The water-swellable threads can refer to aramid or glass threads, which are impregnated with superabsorbent polymer (SAP).

The cavities between and around the optical fibers and the strain reliefs are specially filled with water-swellable wires 6 similar to the middle part of the cable, which is surrounded by fibers and rods in mutual contact.

According to a further embodiment, the strain reliefs may also be surrounded by a layer of some conventional water-swellable material such as SAP. Although preferred embodiments of the invention have been set forth for illustrative purposes, it is to be understood that deviations may be made from this preferred embodiment by those skilled in the art without departing from the scope of the invention.

Claims (9)

10 15 20 25 532 329 5 'PATENT REQUIREMENTS An indoor optical fiber cable (1) comprising: - two optical fibers (2), each optical fiber being surrounded by an outer coating (5), - two strain reliefs (3), the respective outer coating (5) being in direct contact with the two traction sheaths ( 3), and the respective strain reliefs (3) are in direct contact with the two outer coatings (5), and - an outer sheath (4) which tightly encloses the optical fibers (2) and the traction sheaths (3), the optical fi bern (2) and the traction force aviators (3) are intertwined. Cable according to claim 1, wherein the optical fibers (2) and the tensile forces (3) are located so that the corresponding longitudinal axes do not coincide with the central axis of the cable (1). Cable according to Claim 1 or 2, in which the respective optical fiber (2), together with its outer coating (5), has a diameter equal to the respective tensile force relief (3). Cable according to one of Claims 1 to 3, in which the respective traction relief unit (3) is a glass-reinforced plastic rod. A cable according to any one of claims 1 to 4, wherein the outer sheath (4) comprises a halogen-free fire-resistant material. A cable according to any one of claims 1 to 5, wherein it (1) comprises water-swellable material (6) in the cavity of the cable. A cable according to any one of claims 1 to 5, wherein the outer sheath (4) comprises silicone additive. Cable according to one of Claims 1 to 6, in which the diameter of the cable (1) is less than 6 mm. Use of a cable according to claims 1 to 8, in feeding, traction or blowing installations.