JPH04194805A - Optical fiber laying-through method - Google Patents

Abstract

PURPOSE:To improve workability and safety by connecting an extension pipe to the end part of a pipe located in a manhole, and feeding air with a pressure from the ground. CONSTITUTION:A cable 1 previously embedded in a ground is a light and power composite cable wherein, for example, power cables 2 and pipes 3 for an optical fiber cable are arranged in the shape of a star and covering with a plurality of covering layers is effected. An optical cable 5 is delivered in the air pipe 3 in an embedded state through a pipe opening end part 3a in a manhole M by means of a forced feed of air air. For this purpose, an extension pipe 6 is connected to the opening end part 3a and pulled out to the outside of the manhole M. A delivery device 9 comprises a delivery bobbin 10 around which the optical cable 5 is wound in a coil, a forced feed head 11 in which the optical fiber cable 5 unwound from the bobbin 10 is inserted, a compressor 12 to feed compressed air in the head 11, and a heater 13 to dry the compressed air. The delivery device is installed on a ground 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for passing an optical fiber cable into a pipe previously buried underground by pneumatic feeding.

[Prior art and problems to be solved by the invention] European Patent Publication No. 108590 discloses a wiring system in which air is blown into a pipe and an optical fiber cable is fed along the pipe by air pressure. The method is described, but if the pipe is located in a place with sufficient space, such as inside a building, there will be no problem with the work, but if the pipe is buried underground in advance, it is conventional to install it into a manhole. The work was carried out by installing a feeding device such as a feeding bobbin.

For example, if an optical/power composite cable is buried underground in advance, and a few years later, a new optical fiber cable is pneumatically routed into the empty pipe of this composite cable, sewage may leak inside the manhole. The working environment was often poor, with foul-smelling gas accumulating and it was difficult to work inside narrow manholes.

Furthermore, when burying the above-mentioned composite cable, it was necessary to leave sufficient extra length in the empty pipe in anticipation of the future connection of the optical fiber cable to the empty pipe. That is, conventionally, the end of this empty nozzle was directly connected to the pressure feed of the above-mentioned delivery device! - I had to leave some extra length at the end of the empty Tsukibu and pull it out to connect it. (The extra length at the end of the empty pipe was -2, which was stored in the rectilinear junction box in a double-wound shape.) The object of the present invention is to eliminate almost all of this extra length. The purpose of the present invention is to provide a method that allows wiring work to be carried out safely and efficiently in a good environment.

[Means to solve the problem]

The present invention provides a wiring method in which an optical fiber cable is pneumatically fed from the open end of the pipe corresponding to the manhole in a pipe previously buried underground. A joint pipe for drawing outward from the manhole is connected to the opening end inside the manhole, and the pipe is connected to the optical fiber cable feeding bobbin, pressure feeding head, compressor, etc. installed on the ground near the upper opening of the manhole. In this method, the above-mentioned joint pipe is connected to a feeding device consisting of the following, and air is fed under pressure from the ground surface.

[Operation j] A pipe for an optical fiber cable is buried in advance in the ground, including a full optical/electric power unit. -) Mariko's pipe is an empty pipe, and an optical fiber cable will be routed into it later, but even though the remaining length of the end of this pipe inside the manhole is short, If you connect the legs and 2 and 1 degrees apart, it will be long enough so that it can be attached to the outside of the manhole (
It can even reach the ground. The outer end of this joint pipe is installed on the ground and connected to a delivery device, which pumps air from the ground, reducing the amount of time workers have to go down to the manor, improving work efficiency and safety. increases.

〔Example〕

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

In Fig. 1, reference numeral 1 indicates an existing cable buried underground in advance, and for example, as shown in Fig. 2, a power line 2...
This is an optical/power composite cable in which optical fiber cable pipes 3 and 3 are arranged in a star shape and coated with multiple coating layers. That is, in Fig. 2, among the three pipes 3...
The optical fiber cable 21 has already been inserted into the first tree, but the remaining two are empty pipes, and in the present invention, the optical fiber cable 21 is inserted into the empty pipe 3 that is buried underground in advance.
The optical fiber cable 5 is fed by air pressure from the pipe opening end 3a in the manhole M shown in FIG.

A connecting leg vibro, indicated by a broken line in FIG. 1, is connected to the pipe opening end 3a inside the manhole M and pulled out to the outside of the manhole M. In other words, this connecting leg vibro is used for drawing outward from a manhole, and a few meters is sufficient, and it is desirable that it has the same inner diameter as the empty pipe 3. A delivery device 9 is installed on the ground surface 8 near the upper opening 7 of the manhole M.

Specifically, this feeding device 9 includes a feeding bobbin 10 in which an optical fiber cable 5 is wound into a coil, a pressure feed gutter 11 through which the optical fiber cable 5 fed from the bobbin 10 is inserted, and It consists of a compressor 12 that supplies compressed air so that it joins in the pressure feed head '11, a heater 13 that dries this compressed air, etc., and is installed on the ground surface 8.Of course, it is installed on the ground surface 8. In the present invention, even if a part or the whole is placed on the
Defined as something installed on the ground.

The inner end of the connecting leg vibro is connected to the open end 3a of the pipe 3 with a removable connector ↓, and the outer end of the vibro is connected to the discharge part of the pressure-feeding head 11 with a similar connector. Ru. In this way, air is fed from the ground surface 8, and the bobbin I
The optical fiber cable 5 fed out from O is connected to the pressure feeding bend 1
It is pneumatically fed in the following order: 1 → connecting leg vibro → pipe 3.

The pipe 3 in FIG. 2 is shown in FIG. 3 on an enlarged scale.

As is clear from Fig. 3, the inner diameter of the pipe 3 is
The outer diameter of the optical fiber cable 5 is selected to be sufficiently small. For example, the former is selected to be about 6 meters, and the latter is selected to be about 2 meters. Also,
Polyethylene resin is suitable as the material for the pipe 3.6, and the outermost layer of the optical fiber cable 5, the secondary coating layer 14, is made of foamed polyethylene to reduce weight. More preferably, the surface roughness of this secondary coating layer 14 is Rma
When x is 100 μm or more, the air resistance with the pumped air increases, and the air travels well with the air.

In Fig. 1, 15 is a linear junction box (usually cylindrical) placed on the axis of the existing cable 1.
When laying the optical fiber cable 5 into the empty pipe 3 according to the present invention, the extra long bone at the end of the empty pipe 3 is wrapped and stored in this junction box. Pull it out and connect it to the connecting leg vibro as shown in Figure 1. In the present invention, it has been found that it is sufficient for the extra long bones to be rolled up and stored in the junction box to be of a small size.

It should be noted that the number of power lines 2... and pipes 3... that make up the optical/power composite cable as the existing cable l can be increased or decreased, and the arrangement can be changed at will. 3 is buried underground in advance,
preferable. Further, on the ground, the secondary coating layer 1 of the optical fiber cable 5 in the case of having a rough surface of 100 μm or more as described above.
4. Fluorine-based or silicone-based mold release agent□ll! It is preferable to pay out the wiping abrasion agent □ while adhering it to the feeding bobbin 10 and the pressure feed between 7F'llO, in order to improve the wire passing characteristics.

This type of work has the advantage of being easier to perform on the ground.

It is also preferable to provide a mechanism for mechanically pushing the optical fiber cable 5 into the pressure feeding head 11 or immediately upstream thereof.

〔Effect of the invention〕

The present invention is configured as described above, and the work can be performed mainly outside the manhole M, and the work can be performed with good work efficiency and safety. Furthermore, when the cable 1 is laid in advance, the extra length of the pipe 3 can be shortened.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing one embodiment of the present invention, Fig. 2 is a cross-sectional view showing an example of an existing cable, and Fig. 3 is an enlarged sectional view of an optical fiber cable routed inside a pipe. . M... Manhole, 3... Pipe, 3a... Opening end, 5... Optical fiber cable, 6... Joint pipe, 7... Upper opening, 8... Ground surface , 9... feeding device, 10... feeding hobbin, 11... pressure feeding head, 12... compressor.

Claims (1)

[Claims] 1. In a wiring method in which an optical fiber cable is fed by pneumatic feeding into a pipe previously buried underground from an open end of the pipe corresponding to the position of the manhole, the manhole A connecting pipe for drawing outward from the manhole is connected to the opening end located inside the manhole, and a feeding system consisting of an optical fiber cable feeding bobbin, a pressure feeding head, a compressor, etc. installed on the ground near the upper opening of the manhole. An optical fiber cable wiring method characterized by connecting the above-mentioned joint pipe to a device and performing air pressure feeding from the ground surface.