JPS618813A - Optical fiber-containing wire - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electric wire with a built-in optical fiber, and more particularly to an electric wire with a built-in optical fiber having stable optical transmission characteristics.

Electrical cables with built-in optical fibers have the advantage of being able to transmit light and electricity, and are very useful.

[Prior Art] FIG. 3 shows a cross-sectional view of an example of a conventional electric wire with a built-in optical fiber. The optical fiber composite 11 is placed in a groove of a support structure (grooved spacer) 12 inside the pipe 13, and the steel wire 14 is twisted on the outside of the pipe j3. The support structure 12 is made of aluminum, for example, and the steel wire 14 is a zinc-coated or aluminium-coated steel wire. Although not shown, aluminum wires may be further twisted around the steel wires 14.

FIG. 4 shows a cross-sectional view of an example of the optical fiber composite used here. The optical fiber composite 11 is composed of a core glass optical fiber 16 and two layers of reinforcing materials 17 and 18. Glass optical fiber with inner sleeve reinforcement 17
, for example, is coated with silicone resin, and further includes external reinforcement 18,
For example, it is coated with nylon or fluororesin. In a typical optical fiber composite, glass optical fiber 1
6. The outer diameters of the inner sleeve reinforcement 17 and the outer reinforcement 18 are 0.125ia+, 0.4zz, and 0.91, respectively.

However, the coefficients of thermal expansion of the support structure and especially the external reinforcement are large; for example, the coefficients of thermal expansion of aluminum and nylon are approximately 23xl Q-6/°C and approximately 160x10
-”/”C. ), there was a high possibility that the optical transmission loss of the glass optical fiber 16 would increase when the temperature rose. For example, the composite coefficient of thermal expansion of the optical fiber composite described above is approximately 5.
0xl O-'/''C, which is a high value, and furthermore, the thermal expansion property of the supporting structure (the thermal expansion coefficient is about 23xl O-'/''C, for example)
6/”C), and as a result, thermal stress is applied to the glass optical fiber (especially in the length direction of the glass optical fiber).
There was a risk that this would occur. As the operating temperature of electric wires increases, it has been difficult to combine optical fibers with power lines.

[Object of the Invention] An object of the present invention is to provide an electric wire with a built-in optical fiber whose optical transmission characteristics do not deteriorate even when the temperature rises.

J [Constitution of the Invention The gist of the present invention is that the thermal expansion coefficient of the support structure is 10×10-6/”
C or less, and there is a gap between the optical fiber and the optical fiber reinforcing material.

FIG. 2 shows a cross-sectional view of one preferred embodiment of the optical fiber composite used in the present invention. Optical 7 fiber composite 1 comprises a glass optical fiber 6 having a coating 7 and a reinforcement 8
It consists of Since there is a gap 9 between the coating 7 and the reinforcement 8, the coated glass optical fiber is not constrained by the reinforcement 8.

In the coated glass optical fiber, the coefficient of thermal expansion α according to the compound law expressed by the following formula is 10x 10""
/ Must be below C.

In the r formula, aF, SF, and EF are the average thermal expansion coefficient, cross-sectional area, and Young's modulus of the glass optical fiber at room temperature to 230°C, respectively. , So and E.

represent the average coefficient of thermal expansion, cross-sectional area, and Young's modulus of the coating material at room temperature to 230'C, respectively. ].
1 In addition, the average coefficient of thermal expansion of commonly used glass optical fibers is 0.5xl (V'/
'C, Young's modulus is 7000 kg/w shoulder 2. Because the coating (e.g., 100 μII thick) has a very small cross-sectional area compared to the optical fiber (typically 0.91 outer diameter), the composite coefficient of thermal expansion a of the coated glass optical fiber is typically 10 x 10 ""/"C or less can be achieved.

As the thin covering material, for example, silicone resin, acrylic resin, fluororesin, and glass fiber reinforced resin are preferable, and as the reinforcing material, for example, fluororesin is preferable.

For example, the outer diameter of a glass optical fiber including the coating is 0.3
zx, and the inner and outer diameters of the reinforcement are 0 and 0, respectively.
5 wyp and 0.9 am, and the gap dimension is 0.11 as the difference between the stiffener inner radius and the lath optical fiber outer radius.

The average coefficient of thermal expansion of the support structure used in the present invention at room temperature to 230°C is 10xl O-'/'C or less.

In particular, Fe-Ni alloys (usually
(called Invar) is preferred. Here, the average thermal expansion coefficient is set to 10xl O-'/''C or less, which is 200 to 230, which is the maximum temperature of heat-resistant wires below this value.
This is to prevent distortion of more than 0.2%, which is generally considered an allowable distortion, from occurring in optical fibers even when the temperature rises to .degree. The invar wire contains 35 to 42% Ni, and optionally Cr, Mo% Si, Mn, C, Nb, Go,
One or more elements selected from the group consisting of An, Mg, and Ti are contained as additional elements in a total of 0.2 to 10% (the remainder is Fe content). The additive elements are expected to have the effect of lowering the thermal expansion coefficient or improving the Invar strength. Normally, the thermal expansion coefficient of Invar is 2~3×
10-6/'C.

FIG. 1 shows a cross-sectional view of one preferred embodiment of the optical fiber built-in electric wire of the present invention.

Optical fiber composite 1 and support structure 2 as described above
is in pipe 3. The pipe 3 is preferably made of Fe-Ni alloy, but may also be made of aluminum. A zinc-coated or aluminum-coated steel wire 4 is twisted on the outside thereof, and an aluminum wire 5 is further twisted on the outside thereof. It is preferable that the aluminum wire 5 is made of a material whose mechanical properties (especially electrical properties) hardly deteriorate even if the temperature continues up to 230°C, such as an AN-Zr alloy.

[Effects of the Invention] The optical fiber built-in electric wire of the present invention has excellent optical transmission characteristics, especially when the temperature is increased. Even at high temperatures, such as 230'C (which is said to be the maximum allowable temperature for electric wires), there is a permissible strain (approximately 0.2%) in glass optical fibers.
No thermal distortion occurs.

The optical fiber built-in electric wire of the present invention is particularly useful as an overhead ground wire.

[Example] The present invention will be explained in more detail by showing Examples and Comparative Examples below.

Example (Glass optical fiber (outer diameter 0.125 an+) was coated with silicone resin, coating thickness 100μ), and this was made into a fluororesin tube (inner diameter 0.5 ax, outer diameter 0.911)
1I) and the outer diameter is 0.91! The shoulder optical fiber composite was manufactured (see Figure 2). After placing one optical fiber in each groove of the four-grooved support structure made of Fe-Ni alloy, this The aluminum pipe (
The inner diameter was 3.8 mm, the outer diameter was 4.8 mm). Seven aluminum coated steel wires (outer diameter 3,8 xa) are twisted on the outside, and further outside is an Aρ-Zr alloy wire (outer diameter 3.8JI).
14 strands of L (ZrO, 3%) were twisted together (see Figure 1).

The length of the manufactured glass optical fiber built-in electric wire is 200+
Met. The wire is energized and the wire temperature is 150°C and 2
In the case of 00° C., optical transmission loss hardly increased.

Comparative Example Two layers of silicone resin (outer diameter 0.4*l) and nylon (outer diameter 0.9u*) were used as reinforcing materials for the optical fiber composite (see Figure 4), and as materials for the grooved support structure. A conventional electric wire with a built-in glass optical fiber was manufactured using aluminum in the same manner as in the example. 10
A rapid increase in optical transmission loss was observed after several heat cycles at temperatures above 10°C.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a preferred embodiment of the electric wire with a built-in glass optical fiber of the present invention, FIG. 2 is a cross-sectional view of a preferred embodiment of the glass optical fiber composite used in the present invention, and FIG. FIG. 4 is a cross-sectional view of an example of a conventional glass optical fiber composite. FIG. 4 is a cross-sectional view of an example of a conventional glass optical fiber composite. 1.11... Optical fiber composite, 2.12... Support structure, 3, 13... Pipe, 4, 14... Zinc coated or aluminum coated steel wire, 5... Aluminum wire, 6 ,1
6...Glass optical fiber, 7...Coating, 8.17
゜18...Reinforcement material, 9...Gap.

Claims (2)

[Claims] (1) The thermal expansion coefficient of the support structure is 10×10^-^6/
℃ or less, and is characterized by having a gap between the optical fiber and the optical fiber reinforcing material. (2) The optical fiber built-in electric wire according to claim 1, wherein the optical fiber is coated, and the coated optical fiber has a composite coefficient of thermal expansion of 10×10^-^6/°C or less.