JPH0142084Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composite optical fiber cable with a circular cross section, in which optical fiber units are assembled into a cable together with a linear body such as a power line or a communication line with a circular cross section.

Conventionally, this type of composite optical fiber cable, for example, as shown in FIG. 1, two power lines 1, 1 are twisted together, and optical fibers are combined to form a composite optical fiber cable with a circular cross section. In this case, as shown in FIG. 2, an inclusion 2 is placed in the center, and an optical fiber unit 3 and a power line 1 are connected around the inclusion 2. As shown in FIG. , 3 are twisted, and inclusions 2, 3 are further twisted on the outside of the two power lines 1, 1, respectively.
2 to form a cable core with a circular cross section.

However, each of these cable cores needs to have a larger diameter than the cable core shown in FIG. 1, and also requires the inclusion 2, which has the disadvantage of increasing cable cost. Regarding this point, if the outer diameters of the optical fiber units 3, 3 shown in Fig. 3 are made smaller, they can be configured to have the same outer diameter as shown in Fig. 1. However, it is often technically difficult to obtain the desired composite optical fiber cable due to design and manufacturing problems.

This invention was created in view of this point, and the fourth
As shown in the figure, the optical fiber unit 3 is formed into a non-circular shape having a tension member, and this non-circular optical fiber unit is inserted into a spiral outer circumferential groove formed by wire bodies 4, 4 having a circular cross section such as a power line. The basic idea is to twist 3 together.

However, when the linear bodies 4, 4, etc., each having a circular cross section, such as a power line or a unit type communication line, are twisted together, they are generally assembled while undoing the twist that inevitably occurs when they are assembled. It is normal for the linear bodies 4, 4 to gather together at a so-called twist rate of 100%, so the linear bodies 4, 4
When the non-circular optical fiber units 3, 3 are twisted with a twist rate of 100%, the cross section at the 1/4 and 3/4 cycles of the set pitch becomes as shown in Fig. 5, and the non-circular The optical fiber units 3, 3 are twisted into a protruding shape at each period mentioned above. As a result, the cross section shown in Figure 4 and the cross section shown in Figure 5 are repeated every 1/4 of the set pitch in the resulting cable core, resulting in an undesirable cross-sectional shape that is discontinuous in the longitudinal direction. Become.

Therefore, in the present invention, the linear bodies 4, 4... may be untwisted and twisted together, but the optical fiber units 3, 3... having a tension member and having a non-circular cross section may be twisted together.
I try to twist it without twisting it.

As a result, the optical fiber units 3, 3... are twisted in the longitudinal direction, but in the optical fiber units 3, 3..., the optical fibers themselves are housed in a loosely fitted state. Therefore, the twist of the optical fiber units 3, 3 is not directly applied to the internal optical fibers. Therefore, the optical fiber units 3, 3
The negative influence on the optical fiber caused by the twisting of the optical fiber can be eliminated.

The present invention will be explained below with reference to the embodiments shown in FIGS. 6 and 7. In FIG. 6, 11 is a linear body with a circular cross section, and 12 is an optical fiber unit with a non-circular cross section having a tension member. A CV cable with a diameter of 9.7 mmφ was used, and as an optical fiber unit 12 having a tension member, as shown in FIG. The nonwoven fabric 14 is inserted loosely into a vertically molded cylinder so that the outer diameter is 5 mmφ, and the polyethylene 16 is attached with FRP tension members 15 having an outer diameter of 2.5 mmφ on both sides. Commonly used are insert-coated ones with a major axis of 13 mm and a minor axis of 6 mm. Therefore, the cross-sectional shape of the optical fiber unit 12 is longer in the direction where the tension members 15, 15 are located and shorter in the direction perpendicular thereto, and the thickness of the middle part where the optical fiber 13 is located is thicker than the both sides where the tension members 15, 15 are located. It has a thick shape.

These linear bodies 11 and optical fiber units 12
Two pieces of each are prepared, and two linear bodies 1
1 and 11 have a twist rate of 100% and a twist pitch.
It is twisted at 1000mm. Further, the two optical fiber units 12, 12 are connected to the two linear bodies 11,
The tension members 15, 15 on both sides are twisted into two helical outer circumferential grooves formed by the wires 11 without twisting, and the tension members 15, 15 portions on both sides each have two linear bodies 1
1 and 11. Therefore, the peripheral shape of the cable core is approximately circular.

Next, the cable core constructed as shown in Fig. 6 is wrapped with plastic, and then a 1.5 mm thick polyethylene sheath is extruded to form a composite optical fiber cable with an outer diameter of 25 mmφ. did.

As a result, the optical fiber unit 1
The configuration is completely the same as without 2 and 12, and the cable weight is 1500 kg/
100Kg/Km of Km is optical fiber unit 12,
It is only an increase of 12.

Also, the process change in transmission loss of optical fiber 13 is 8
It was confirmed that there was almost no heart.

In the embodiment of the present invention, the linear body 11 is composed of a CV cable for power.
The present invention is not limited to this case, and may be a communication unit with a circular cross-sectional shape or a simple rope, and the number is not limited to two, but may be more than two.

Moreover, the linear bodies may be twisted together without twisting, or may be twisted together with a twisting ratio other than 100%.

As described above, since the composite optical fiber cable of the present invention has the above-described configuration, the optical fiber unit can be easily accommodated in the spiral outer circumferential groove formed between adjacent linear bodies, and the optical fiber The position of the unit is stabilized, and the cable core can be shaped into a nearly circular shape. At the same time, there is an advantage that the outer diameter of the cable does not need to be increased much.

Further, since the optical fiber unit is twisted together without twisting, each pitch is twisted once. However, since the optical fiber itself is accommodated in this optical fiber unit in a loosely fitted state, it is not directly subjected to the above-mentioned twisting. There is also no risk of an increase in optical fiber transmission loss or optical fiber breakage.

In addition, the tension members on both sides of the optical fiber unit directly receive the tensile force during cable core construction or installation, so the optical fiber has the advantage that it is difficult to break even if tensile force is applied from the outside. be.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing a conventional power cable core, Figs. 2 and 3 are sectional views showing different examples of conventional composite optical fiber cable cores, and Figs. FIG. 6 is a sectional view of a composite optical fiber cable core showing an embodiment of the invention, and FIG. 7 is a cross-sectional view of the optical fiber cable core used in FIG. 6. FIG. 3 is an enlarged sectional view of the unit. 11... Linear body, 12... Optical fiber unit, 13... Optical fiber, 15... Tension member.

Claims (1)

[Scope of utility model registration request] A plurality of linear bodies having a circular cross section are twisted together, and a spiral outer circumferential groove formed between the adjacent linear bodies has tension members on both sides and an optical fiber in the middle thereof. A common coating is applied to them, and the cross-sectional shape is longer in the direction of the tension member and shorter in the direction perpendicular to it, and the middle part where the optical fiber is located is thicker than the parts on both sides where the tension member is located. an optical fiber unit in which the optical fiber is loosely fitted within the common covering, and the tension member portions on both sides thereof are aligned with the mutually adjacent linear bodies, A composite optical fiber cable characterized by being twisted together without twisting.