JPH095589A - Optical fiber cable - Google Patents

Abstract

PURPOSE: To provide an optical fiber cable whose outside diameter is made small, whose tensile strength is high and which has flexibility. CONSTITUTION: This optical fiber cable is constituted of a grooved inclusion 1 constituted by spirally forming plural grooves 1A provided at specified intervals on an outer periphery in a longitudinal direction, plural tensile force absorbing rods 2 whose <=1/3 of the outer periphery is housed in the groove 1A of the inclusion 1, a coated optical fiber 3 arranged between the rods 2 and on the outer periphery of the inclusion 1, a buffer layer 4 provided on the optical fiber 3, and a protective covering layer 5 provided on the buffer layer 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of an optical fiber cable.

[0002]

2. Description of the Related Art In recent years, an optical fiber communication network has been constructed with overhead power transmission lines (including overhead ground lines). When constructing an optical fiber communication network on an existing overhead transmission line, an optical fiber cable is wound around the outer periphery of the overhead transmission line, and also when constructing an optical fiber communication network on a new overhead transmission line. Is performed by placing a storage pipe inside the overhead power transmission line, manufacturing an optical fiber composite overhead power transmission line in which an optical fiber cable is stored in the storage pipe, and installing it between steel towers.

As described above, the optical fiber cable wound around the outer circumference of the overhead power transmission line is required to have a small outer diameter in order to suppress wind pressure load after laying, and various tensile loads applied after laying. It is required to endure. On the other hand, the optical fiber cable stored in the storage tube is
The optical fiber core wire may be broken after the optical fiber composite overhead power transmission line is installed between the towers, and it is necessary to replace the optical fiber cable at this time, but the optical fiber cable newly drawn into the storage pipe is too large. It is required to withstand a tensile load.

Conventional optical fiber cables are made of metal or FR.
A structure in which a plurality of optical fiber core wires are arranged around a tension member made of P, a press winding layer formed by winding a plastic tape or the like is formed on the outer circumference thereof, and a sheath formed of plastic or the like is provided on the outer circumference thereof. .

[0005]

However, in the optical fiber cable having the above structure, it is necessary to use a thick tension member in order to increase the tensile strength, and when such a thick tension member is used. Although the tensile strength can be increased, the outer diameter of the optical fiber cable becomes large, the wind pressure load increases, the flexibility of the optical fiber cable is lost, and it becomes difficult to wind around the overhead power transmission line. There was a problem.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides an optical fiber cable having a small outer diameter, high tensile strength, and flexibility. Is a grooved inclusion formed by spirally forming a plurality of grooves provided at a predetermined interval on the outer periphery along the longitudinal direction, and a plurality of tension absorbing members housed in the plurality of grooves of the grooved inclusion. Rods, an optical fiber core wire arranged between the tension absorbing rods and on the outer circumference of a grooved inclusion, a buffer layer provided on the optical fiber core wire, and a protective coating layer provided on the buffer layer And (claim 1). Further, the plurality of tension absorbing rods housed in the plurality of grooves of the grooved inclusion are characterized in that one third or less of the outer circumference thereof is housed (claim 2).

[0007]

When a plurality of tension absorbing rods are used, the tension applied to the optical fiber cable can be shared by the tension absorbing rods, so that the optical fiber cable having high tensile strength can be obtained. Further, since the diameter of one tension absorbing rod can be reduced by using a plurality of tension absorbing rods, the flexibility of the optical fiber cable is not impaired.

Further, the tension absorbing rod is provided in the groove of the grooved inclusion,
Since 1/3 or less of the outer circumference is arranged in a housed state, the length of the outer circumference excluding the groove of the grooved inclusion can be made large. Therefore, without increasing the outer diameter of the grooved inclusion, the number of optical fiber core wires arranged at the position can be increased. That is, since the diameter of the optical fiber core wire is small, the number of optical fiber core wires arranged on the outer periphery excluding the grooves of the grooved inclusions varies depending on the size of the grooved inclusions. If the tension absorbing rod is arranged so as to be shallow, that is, one third or less of the outer circumference thereof is accommodated, the length of the outer circumference excluding the groove of the grooved inclusion can be made large. Even if the diameter is not increased, the number of optical fiber core wires arranged at the position can be increased. Furthermore, since it is not necessary to increase the outer diameter of the grooved inclusion and the diameter of the tension absorbing rod is small as described above, the outer diameter of the optical fiber cable can be reduced as a whole.

[0009]

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of an optical fiber cable according to the present invention, in which 1 is a grooved inclusion, 2 is a tension absorbing rod, 3 is an optical fiber core wire, 4 is a buffer layer, and 5 is a protective coating. It is a layer.

The grooved inclusion 1 is made of synthetic resin or the like, and three grooves 1A are provided on the outer periphery thereof at predetermined intervals. The three grooves 1A are formed in a spiral shape along the longitudinal direction. Further, the depth of the three grooves 1A is such that one third or less of the outer circumference of the tension absorbing rod 2 is accommodated.

The tension absorbing rod 2 is formed of a metal or glass fiber aggregate or the like, and 1/3 or less of the outer periphery thereof is housed in the groove 1A of the grooved inclusion 1.

An optical fiber core wire 3 is arranged between the tension absorbing rods 2 and on the outer periphery of the grooved inclusion 1. Since the groove 1A formed in the grooved inclusion 1 has a shallow depth, the outer circumference of the grooved inclusion 1 can be made long. Therefore, the number of optical fiber core wires 3 arranged between the tension absorbing rods 2 and on the outer periphery of the grooved inclusion 1 can be increased without increasing the outer diameter of the grooved inclusion 1.

A buffer layer 4 made of a silicone resin or the like is provided on the optical fiber core wire 3, and a protective coating layer 5 made of a heat resistant resin is provided on the outer periphery thereof.

2 and 3 show another embodiment of the present invention. The one shown in FIG. 2 is a grooved inclusion 1
The number of the grooves 1A provided in the groove 1 is two, and the groove 1A provided in the grooved inclusion 1 is shown in FIG.
Four A's are provided at opposite positions. 2 and 3, the point that the depth of the groove 1A is set to a depth that accommodates 1/3 or less of the outer circumference of the tension absorbing rod and the point that the groove is spiral are the same as in the above-described embodiment. Further, in FIGS. 2 and 3, the same parts as those in FIG.

Next, specific examples of the present invention will be described. A grooved inclusion having an outer diameter of 2.4 mm was formed from a synthetic resin (plastic). 120 on the outer circumference of the grooved inclusion.
Three grooves were provided at intervals of one degree. The three grooves were formed in a spiral shape along the longitudinal direction. Further, the depth of the three grooves is set to a depth that accommodates 1/3 of the outer circumference of the tension absorbing rod. A tension absorbing rod having an outer diameter of 0.6 mm manufactured by FRP was placed in this groove. An optical fiber core with an outer diameter of 0.4 mm is attached to the outer circumference of the grooved inclusion between the tension absorbing rods as a whole.
Five were arranged. A buffer layer made of silicon resin is provided on the optical fiber core, and a heat-resistant resin (fluorine resin) is provided around the buffer layer.
An optical fiber cable was manufactured by providing a protective coating layer consisting of The outer diameter of the optical fiber cable is 5.0 mm.

The above optical fiber cable is used for 240 mm ²
Was wound around a steel core aluminum stranded wire at a winding pitch of 500 mm. The fiber optic cable was flexible and could be easily wrapped. A steel core aluminum stranded wire wound with an optical fiber cable was installed in a wind tunnel test facility and the wind speed was 20 m.
When the drag coefficient increase rate when the wind speed is 40 m / s and the drag coefficient increase rate when the wind speed is 40 m / s are measured, the drag coefficient increase rate at the wind speed of 20 m / s is 1.054 times, and the wind speed is 40 m / s.
At that time, the drag coefficient increase rate was 1.006. If the drag coefficient is increased to this extent, there is no need to reinforce the steel tower that supports the overhead transmission line, and there is no particular problem. In addition, an experiment was conducted in which the above optical fiber cable was pulled into a straight aluminum hollow tube with a predetermined tensile load, and the optical fiber cable was not broken in the straight aluminum hollow tube. I was able to pull in.

The number of grooves provided in the grooved inclusion used in the present invention is not particularly limited and may be, for example, five. Also, the material of each part is not particularly limited. Further, the tension absorbing rod may be arranged in the groove of the grooved inclusion in such a manner that one third or more of the outer circumference thereof is housed.

[0018]

As described above, since the optical fiber cable according to the present invention uses a plurality of tension absorbing rods, the tension applied to the optical fiber cable can be shared by the tension absorbing rods. Therefore, an optical fiber cable having high tensile strength can be obtained. Moreover, since the diameter of one tension absorbing rod can be reduced by using a plurality of tension absorbing rods, the flexibility of the optical fiber cable is not impaired and the winding operation can be easily performed.

The tension absorbing rod is provided in the groove of the grooved inclusion,
Since one third or less of the outer circumference of the grooved inclusion is arranged in a housed state, the outer circumference of the grooved inclusion can be made long. Therefore, it is possible to increase the number of optical fiber cables arranged at the position without increasing the outer diameter of the grooved inclusion. Further, since it is not necessary to increase the outer diameter of the grooved inclusions and the diameter of the tension absorbing rod is small, the outer diameter of the optical fiber cable can be reduced as a whole, thereby increasing the wind load. Nothing.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing another embodiment of the present invention.

FIG. 3 is a sectional view showing still another embodiment of the present invention.

[Explanation of symbols]

 1 Inclusion with groove 2 Tension absorbing rod 3 Optical fiber core wire 4 Buffer layer 5 Protective coating layer

Claims (2)

[Claims] 1. A grooved inclusion formed by spirally forming a plurality of grooves provided on the outer periphery at predetermined intervals along a longitudinal direction, and a plurality of grooved inclusions housed in the plurality of grooves. Of the tension absorbing rod, an optical fiber core wire arranged between the tension absorbing rods and on the outer circumference of the grooved inclusion, a buffer layer provided on the optical fiber core wire, and provided on the buffer layer. An optical fiber cable consisting of a protective coating layer. 2. The optical fiber cable according to claim 1, wherein the tension absorbing rods accommodated in the grooves of the grooved inclusions accommodate one third or less of the outer circumference thereof.