JPH0222905Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of an optical fiber composite overhead electric wire in which an optical fiber is housed in the overhead electric wire.

[Prior art] An optical fiber is housed in an overhead electric wire and connected to the overhead wire.
2. Description of the Related Art Optical fiber composite overhead wires, which constitute communication lines using overhead wires as carriers, have recently been rapidly put into practical use because communication lines can be laid by a simple method. In this case, the coefficient of linear expansion of the optical fiber is one order of magnitude smaller than that of the conductor, and the elastic elongation of the conductor is also larger, so there is a difference between the thermal expansion of the wire and the amount of elongation due to the tension of the wire after the overhead wire is connected. , which is applied as abnormal tension to the optical fiber, causing localized stress that may adversely affect the light conduction performance or, in extreme cases, cause the optical fiber to break.

Therefore, in order to avoid the above-mentioned problems, the optical fiber is accommodated through a cushion material such as home rubber, and even if the abnormal tension is applied to the optical fiber, this cushion material absorbs it well. Measures are being taken to prevent accidents like the one described above from developing.

[Problems to be solved by the invention] However, when the wire becomes hot, the inclusions thermally expand in the radial direction of the wire, which forces the optical fiber to expand in the radial direction. It was found that unexpected tension may occur.

[Means for Solving the Problems] In view of the above-mentioned circumstances, the present invention provides an optical fiber that does not cause the above-mentioned abnormal tension in the optical fiber housed therein even when the electric wire reaches a high temperature. The aim is to provide a composite overhead wire, and its gist is that an optical fiber unit is disposed within a housing space formed within the overhead wire, and the optical fiber unit is made of a heat-shrinkable material. This is an optical fiber composite overhead wire that has optical fibers arranged on the outside.

[Example] The present invention will be explained below using examples.

FIG. 1 is a sectional view showing an example of an optical fiber composite overhead wire according to the present invention. In the figure, 1 is a heating wire arranged as necessary, 2 is a heat-shrinkable tube made of polyethylene, etc., 3 is an optical fiber wound and arranged around the outer periphery of the heat-shrinkable tube, and 4 is a protection wire. a cushioning coating layer that protects the internal optical fiber from damage;
Reference numeral 6 indicates an accommodating body which creates a accommodating gap for accommodating an optical fiber made of, for example, an aluminum pipe, and 6 indicates conductive wires twisted to the outside.

In FIG. 1, the heat-shrinkable tube 3 is not yet heated and is in an expanded state. The electric wire according to the present invention may be wired in the state shown in FIG. 1, and then the heating wire 1 may be heated to heat-shrink the heat-shrinkable tube 2 as shown in FIG. 2, or the wire may be wired in the state shown in FIG. For example, the heat-shrinkable tube 2 may be heat-shrinked by performing the above-mentioned heating in a factory and before the overhead wire is installed.

Furthermore, in the present invention, the heating wire is omitted and the wire itself is heated by energization, or the temperature rise during energization is used to create a heated state, and the heat shrinkable tube is contracted by this heat. Good too.

In the above embodiment, an example was shown in which a heat-shrinkable tube was used as the heat-shrinkable member, but the present invention is not limited to the above-mentioned tube-shape, and for example, a sheet-like material formed into a spiral shape. However, the shape is not particularly limited. Further, in the above embodiment, a pipe is used to form a space for accommodating an optical fiber, but an appropriate space may be formed by twisting segmented wires. It's okay.

In the present invention, the heat-shrinkable member is initially in an expanded state, and optical fibers are arranged around its outer circumference.
After that, the heat-shrinkable material is heated to cause it to shrink, so after it is heat-shrinked, a gap is created between the optical fiber and the optical fiber. Therefore, even if the electric wire elongates, the effect on the optical fiber can be negligible or extremely small.

[Effects of the invention] As described above, according to the optical fiber composite overhead wire according to the invention, even if the wire elongates due to thermal expansion or overhead wire tension, the elongation does not affect the internal optical fiber. Therefore, it is possible to maintain a highly reliable state at all times, and today, when optical fiber composite overhead wires are being put into practical use in earnest, they have great industrial utility.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the optical fiber composite overhead wire according to the present invention, and FIG. 2 is a sectional view showing the heat-shrinkable tube in FIG. 1 in a contracted state. 1; heating wire; 2; heat-shrinkable member; 3; optical fiber; 5; container; 6; wire.

Claims (1)

[Claims for Utility Model Registration] 1. An optical fiber unit is arranged in a housing space formed in an overhead electric wire, and the optical fiber unit is one in which optical fibers are arranged outside a heat-shrinkable member. Optical fiber composite overhead wire. 2. The composite overhead electric wire according to claim 1, which is a heat-shrinkable member in which a heating wire is further interposed.