JPH02208611A - Nonmetallic optical fiber cable - Google Patents

Abstract

PURPOSE:To obtain the nonmetallic optical fiber cable which is high in strength, small in diameter and light in weight and is excellent in flexibility and economy by substantially closely disposing plural tensile bodies around the optical fiber disposed at the cable center. CONSTITUTION:The optical fiber 1 is positioned at the center of the cable and spacers 4 hold the optical fiber 1 and the polyethylene (PE) coated FRP twisted wires 11 to 14 in such a manner that the PE-coated FRP stranded wires 11 to 14 enclose the circumference of the optical fiber. Retaining winding of a plastic tape 5 is applied on the outer side of the spacers 4 and an outer coating 6 is formed above the tape. Each of these PE-coated FRP stranded wires 11 to 14 is constituted by twisting and doubling 7 pieces of FRP rods 2 and coating these rods with PE. The tensile bodies function as the armor of the cable as well and the structure highly strong to the tensile force in the axial direction and the compressive force in the diametral direction is obtd. The diameter and weight of the cable are reduced and the flexibility as the cable is improved.

Description

[Detailed description of the invention] Industrial applications The present invention relates to non-metallic optical fiber cables.

More specifically, the present invention relates to the structure of a non-metallic optical fiber cable that has high strength, small diameter, light weight, and excellent economic efficiency.

Conventional technology Among optical fiber cables, cables that do not contain any metal are called non-metallic cables. Non-metallic cables are not subject to electrostatic induction or electromagnetic induction, so they are installed in parallel with electrical cables. It can be combined with the overhead ground wire or attached to a power cable.

Conventional non-metallic optical fiber cables generally use FRP (I-fiber reinforced plastic) rods or aramid fibers as the tensile strength members.

FIGS. 2(a), (b) and (C) show radial cross-sectional views of conventional non-metallic optical fiber cables.

The non-metallic optical fiber cable shown in Fig. 2(a) uses an FRP rod 2 as a tensile strength member, and the optical fibers 1 are directly twisted in a spiral around the FRP rod 2 placed at the center. . A cushioning material 3 such as plastic yarn is placed over these for protection, and an outer covering 6 is formed on top of which a plastic tape 5 is applied.

Furthermore, the non-metallic optical fiber cable shown in FIG. 2(c) also uses an FRP rod 2 as a tensile strength member, but a plastic spacer 4 containing an optical fiber l is placed around the FRP rod 2. The arrangement differs from that in FIG. 2(a). That is, Figure 2 (c)
In the non-metallic optical fiber cable, an FRP rod 2 is arranged at the center of a spacer 4. On the surface of the spacer 4, a groove 41 in which the optical fiber 1 is accommodated is formed continuously in the axial direction. Furthermore, a plastic tape 5 is wrapped around the spacer 4, and an outer covering 6 is formed thereon.

The non-metallic optical fiber cable shown in FIG. 2(C) uses aramid fiber 7 as a tensile strength member instead of the FRP rod. This non-metallic optical fiber cable consists of an optical fiber 1 and an aramid fiber 7 twisted together, the outside of which is wrapped with a plastic tape 5, and an outer covering 6 is formed thereon.

Problems to be Solved by the Invention As described above, in conventional non-metallic optical fiber cables, FRP rods are widely used as tensile strength members to withstand the tension applied during installation. However, compared to the steel wire used in metallic optical fiber cables, Young's modulus is small at approximately A, so in terms of tension design,
It was necessary to make the outer diameter of the FRP rod thicker than that of the steel wire.

As a result, not only the flexibility of the cable is impaired, but also the rigidity of the FRP rod is large, so there are problems in handling from a safety standpoint.

In order to improve flexibility, some cables have an FRP rod with an outer diameter equivalent to that of a steel wire, and have a tension design using aramid fibers or only aramid fibers. However, such cables are expensive because aramid fibers are expensive.

Further, armor structures that can be used under severe installation conditions such as direct burial include structures in which FRP rods or the like are stranded in multiple strips on the outer covering, and structures in which hard plastic is coated in two layers. However, in either case, it is difficult to reduce the diameter and weight, and there are problems in that the flexibility of the cable is impaired.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a non-metallic optical fiber cable having high strength, small diameter, light weight, flexibility, and economical efficiency, which solves the problems of the prior art described above.

Means for Solving the Problems According to the present invention, a non-metallic optical fiber cable comprising an optical fiber, a tensile strength member, and an outer coating, the non-metallic optical fiber cable containing no metal as a constituent material,
A non-metallic optical fiber cable is provided, characterized in that a plurality of tensile strength members are arranged substantially without gaps around an optical fiber arranged at the center of the cable.

PSYCHOLOGY In the non-metallic optical fiber cable of the present invention, an optical fiber is arranged at the center of the cable, and a plurality of tensile strength members are arranged around the optical fiber with substantially no gaps. Therefore, the tensile strength member also functions as a cable armor.
The structure has high strength against both axial tensile force and radial compressive force. Since no special armor is required on the outer sheath of the cable, it is possible to reduce the diameter and weight, and it is also economical.

Further, when polyethylene-coated FRP stranded wire is used as the tensile strength member, the cable has particularly excellent flexibility. Furthermore, since the optical fiber is located at the center of the cable, it is less susceptible to distortion due to bending, etc., and long-term reliability can be improved.

Embodiment FIG. 1 shows a cross-sectional structure of an embodiment of the non-metallic optical fiber cable of the present invention.

In the non-metallic optical fiber cable shown in Figure 1,
Optical fiber 1 is located at the center of the cable, and 4 fibers are placed around it.
The spacer 4 holds the optical fiber 1 and the polyethylene-coated FRP strands 11-14 so that the polyethylene-coated FRP strands 11-14 surround it. Spacer 4
A plastic tape 5 is wrapped around the outside, and an outer covering 6 is formed on top of the plastic tape 5.

In the non-metallic optical fiber cable of this embodiment, the polyethylene-coated FRP strands 11 to 14 have a structure in which seven FRP rods 2 are twisted together and coated with polyethylene. Since the periphery is surrounded by polyethylene-coated FRP stranded wires having such a configuration, in the non-metallic optical fiber cable of the present invention, the optical fiber 1 is not only subjected to tension in the axial direction of the cable but also to compressive stress in the radial direction. Also protected from. Furthermore, the FRP rods 2 used for the polyethylene-coated FRP strands 11 to 14 are stranded with a small diameter, and therefore have sufficient flexibility.

A sectional view of the spacer 4 used in the non-metallic optical fiber cable of this example is shown in FIG.

This spacer 4 uses high-density polyethylene (HDPE), the centers of the polyethylene-coated FRP strands 11 and 13 are located on one diameter of the cable, and the polyethylene-coated FRP strands 11 and 13 are opposed to each other with the cable center in between. The center of the cable is on a diameter perpendicular to the diameter of the cable, and the polyethylene-coated FRP strands 11 and 12.12 and 1
It is formed so that the outer peripheries of No. 3 are held at a position where they are almost in contact with each other. Furthermore, the optical fiber l is housed in the center of the cable in the spacer 4, and on the outside, the center of the polyethylene-coated FRP stranded wire 14 is connected to the polyethylene-coated FRP stranded wire 1.
2, the polyethylene-coated FRP stranded wires 12 and 14 face each other across the cable center, and the polyethylene-coated FRP stranded wires 11 and 14
．． A groove 10 in which the polyethylene-coated FRP stranded wire 14 is housed is continuously carved in the axial direction at a position where the outer circumferences of the wires 13 and 14 substantially touch each other. Polyethylene coated FRP
When the twisted wires 11 to 13 are held in a spiral shape, the flexibility is further improved and the effect of protecting the optical fiber 1 is also increased.

In this case, the polyethylene-coated FRP strands 11 to 13 are
It is also preferable that it is held in a spiral shape in one direction in the axial direction, and it is also preferable that it is held in a spiral shape that reverses in the middle. In these cases, of course, the groove 10 is such that the polyethylene-coated FRP strands 14 draw an axial spiral similar to that of the polyethylene-coated FRP strands 11 to 13, and the polyethylene-coated FRP strands 11 to 14 draw the above-mentioned spiral in the spacer 4. It is engraved so that it can be placed in the correct position. Also, groove 1
It is also preferable to fill the voids within 0 with waterproof resin.

In this example, an optical fiber coated with an ultraviolet curable resin was used as the optical fiber 1, but the optical fiber 1 could also be a nylon resin coated optical fiber wire or a multi-core tape-shaped core wire coated with an ultraviolet curable resin. It is also possible to use .

As explained above, in the non-metallic optical fiber cable of this embodiment, a plurality of polyethylene-coated FRP strands, which are tensile strength members, are arranged so as to surround the optical fiber arranged at the center of the cable. Therefore, the optical fiber is protected not only from tension but also from compressive stress in the radial direction by the polyethylene-coated FRP strands, so no armor is required. Therefore, it is possible to reduce the diameter and weight, and it is economical because expensive aramid fibers are not used. Furthermore, unlike conventional ones, it uses twisted FRP rods with a small diameter, so it is highly flexible.

Effects of the Invention As detailed above, the non-metallic optical fiber cable of the present invention can be applied to all installation environments, including underground, conduit, and overhead, because the tensile strength member also serves as the cable armor. be. Furthermore, since the optical fiber is placed in the center and the tensile strength body surrounds it without any gaps, it is particularly effective for use in rodent and bulletproof applications.

Furthermore, since multiple tensile strength members are arranged, each individual member can be made small in diameter and has great flexibility, and this effect can be further enhanced by using polyethylene-coated FRP strands as the tensile strength members. It will be done.

Also, there is no need to use expensive materials such as aramid fibers.
Since armor can also be omitted, costs can also be reduced.

[Brief explanation of the drawing]

FIG. 1(a) is a cross-sectional view of an embodiment of the non-metallic optical fiber cable of the present invention, and FIG. 1(5) is a cross-sectional view of the spacer of the non-metallic optical fiber cable of FIG. 1(a). FIG. 2A to FIG. 2C are cross-sectional views of a conventional non-metallic optical fiber cable. [Main reference numbers] 1. Optical fiber, 2. FRP rod, 3. Cushioning material, 4. Spacer, 5. Plastic tape, 6. Outer wave, covering, 7. Aramid fiber, 10 ··groove,

Claims (5)

[Claims] (1) In a non-metallic optical fiber cable comprising an optical fiber, a tensile strength member, and an outer covering, and whose constituent materials do not contain metal, a plurality of optical fibers are arranged around the optical fiber arranged at the center of the cable. A non-metallic optical fiber cable characterized in that tensile strength members are arranged with substantially no gaps. (2) The non-metallic optical fiber cable according to claim 1, wherein the tensile strength member is a polyethylene-coated FRP stranded wire made by twisting a plurality of FRP rods and coating them with polyethylene. (3) The non-metallic optical fiber cable according to claim 1 or 2, wherein the tensile strength member is arranged spirally in the axial direction of the cable. (4) Claims (1) to (3) characterized in that the optical fiber and the tensile strength body are held by spacers.
) The non-metallic optical fiber cable according to any one of the above. (5) Claim (4) characterized in that the spacer has a groove continuous in the axial direction on its surface, and the optical fiber and at least one of the tensile strength members are accommodated in the groove.
Non-metallic fiber optic cables listed in .