JPH04172402A - Method of feeding optical fiber into narrow long-distance duct - Google Patents

Abstract

PURPOSE:To feed one continuous optical fiber into a narrow long-distance duct casting without forcing tension to the optical fiber by connecting a pneumatic type optical fiber feeding device on the inlet end of each narrow duct divided into the longitudinal direction, opening the outlet end and arranging an optical fiber accumulation container on the second feeder device and thereafter. CONSTITUTION:An optical fiber 11 fed into a narrow duct 15a by means of a first pneumatic type optical fiber feeder device 13a is accumulated in an optical fiber accumulation container 35a and, when the accumulation is adequate, the tip of the optical fiber 11 is passed through a gas sealed portion 21b of an optical fiber feeder device 33a, after which compressed gas is pressed through a supply inlet 17b of the compressed gas. The fiber 11 then is fed into a duct 15b by virtue of the force acting between itself and the compressed gas flowing inside the duct 15b. Because the outlet end of the duct 15b is opened inside a container 35b, there is a pressure difference at the inlet and the outlet which causes the fiber 11 to proceed smoothly into the duct 15b and further into the container 35b. By repeating the same thereafter, the fiber 11 can be fed into the narrow duct.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for installing a continuous optical fiber in a long-distance narrow-diameter conduit consisting of a plurality of narrow-diameter conduits arranged in series in the longitudinal direction. It is related to the method of sending.

[Conventional technology and its issues]

As a method of feeding an optical fiber into a small diameter pipe, there is a method of feeding compressed gas from one end of the small diameter pipe. As a conventional example of an apparatus for realizing this method, the one shown in FIG.
Publication No. 07).

In the figure, 11 is an optical fiber, 13 is a pneumatic optical fiber feeding device, and 15 is a small diameter conduit. 17 is a compressed gas supply port of the pneumatic optical fiber feeding device 13, 19 is an optical fiber feeding mechanism, and 21 is a gas seal portion at the optical fiber inlet.

The optical fiber 11 enters through the gas seal section 21 and is sent out by the sending mechanism 19. On the other hand, compressed gas is supplied from the supply port 17 by a compressor or a high-pressure gas cylinder (not shown). Then, the optical fiber 11 is fed into the narrow diameter pipe 15 by a hydrodynamic force acting between the optical fiber 11 and the compressed gas flowing inside the small diameter pipe 15. At this time, the flow rate of the compressed gas flowing through the narrow diameter pipe 15 needs to be faster than the delivery rate of the optical fiber 11. However, small diameter tubes are used for compressed gas! 15. Due to the frictional force with the inner surface, when the pressure is constant, the flow rate of compressed gas becomes slower as the pipe length increases, and if the pipe length is long, it may not be possible to ensure a practically sufficient delivery speed.

When the pipe length is long, the flow rate of the compressed gas can be maintained by increasing the pressure of the compressed gas, but the maximum pressure is limited by the pressure resistance strength of the pipe. For this reason, in practice, there is a limit to the length in which the optical fiber can be continuously fed.

In order to eliminate the above-mentioned limit on the feeding length, a method has been proposed in which compressed gas is supplied from the middle of a small diameter pipe as shown in FIG. 4 (Japanese Patent Laid-Open No. 1-292302).

That is, in order to lay optical fiber over a long distance, supply ports 17a, '17b, 17 supply compressed gas.
c... are provided at multiple locations at intervals in the longitudinal direction of the small diameter pipe line 15, and second, third... supply ports 17b,
The supply of compressed gas from 17c... is started after each optical fiber passes through its respective supply port.

However, in this method, since the narrow diameter pipe 15 is continuous, the pressure difference between the entrance of the optical fiber and the part to which the compressed gas is supplied from the middle becomes small, and the flow rate of the compressed gas in this part becomes slow. This made it difficult to feed the optical fiber.

[Means for solving problems and their effects]

The present invention provides a method for feeding an optical fiber into a long-distance narrow-diameter conduit, and its configuration is such that the long-distance narrow-diameter conduit, in which a continuous optical fiber is laid, is divided into a plurality of sections in the longitudinal direction. A pneumatic optical fiber feeding device is connected to the inlet end of each divided small diameter pipe, and the outlet end of each small diameter pipe is left open. It is characterized by feeding an optical fiber.

The pneumatic optical fiber feeding device was connected to the inlet end of each divided narrow-diameter pipe, and the outlet end of each narrow-diameter pipe was left open to control the pressure between the inlet and outlet for each section. This is to make it possible to obtain a difference, increase the flow rate of compressed gas, and feed the optical fiber at a speed sufficient for practical use.

In addition, if an optical fiber storage container is provided in the pneumatic optical fiber feeding device located between the small diameter pipes, and the optical fiber is temporarily stored in the container and then sent out (
(Invention of Claim 2) Even if the feeding speeds in each section are somewhat uneven, a continuous optical fiber can be fed into a small diameter conduit divided into a plurality of parts without applying excessive tension to the optical fiber.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the method for feeding an optical fiber into a long-distance narrow-diameter conduit according to the present invention.

A long-distance narrow-diameter conduit in which a continuous optical fiber 11 is installed is divided into a plurality of sections in the longitudinal direction, and the entrance end of each divided narrow-diameter conduit 15a, 15b, 41c, etc. , fig.
The same pneumatic fiber feeding device 1 as the conventional one shown in 3.
3aS13b, 13c... are connected, and the outlet ends 31a, 31b... of each small diameter pipe are open to the atmosphere.

The optical fiber 11 enters through the gas seal section 21 and is sent out by the sending mechanism 19. On the other hand, compressed gas is supplied from the supply port 17 by a compressor or a high-pressure gas cylinder (not shown). Then, the optical fiber 11 is sent into the narrow diameter pipe 15 by the hydrodynamic force acting between the optical fiber 11 and the compressed gas flowing in the small diameter pipe I5. At this time, since the outlet end 31a of the small diameter pipe 15H is open, the compressed gas is released into the atmosphere, and the optical fiber is smoothly fed into the small diameter pipe 15a.
The second pneumatic optical fiber feeding device 13b is reached. The optical fiber 11 that has reached the second pneumatic optical fiber feeding device 13b is fed into the small diameter conduit 15b by the same action as described above, and reaches the third pneumatic optical fiber feeding device 13c. Thereafter, the same process is repeated to feed the optical fiber 11 into the small diameter pipe.

According to this feeding method, since the outlet end of each small-diameter pipe line is open, a pressure difference between the input and exit of each section can be obtained, and the flow velocity is the same in each section, making it possible to smoothly feed the optical fiber. I can do it.

In addition, in this example, an example was shown in which a gap was provided between the outlet end of the small diameter pipe line and the pneumatic optical fiber feeding device to open the outlet end of the small diameter pipe line. The opening form of the outlet end of the conduit is not limited to this; for example, the outlet end of a small diameter conduit may be connected to the next pneumatic optical fiber feeding device, and an exhaust hole may be installed in the small diameter conduit near the connection point. By providing an open structure, the same operation and effect as described above can be obtained even if the compressed gas is released from the exhaust hole.

FIG. 2 shows another embodiment of the method of feeding an optical fiber into a long-distance narrow-diameter conduit according to the present invention.

Components having the same functions as those in Figure 1 are given the same reference numerals.

In this embodiment, the first pneumatic optical fiber feeding device 13a is the same as in the previous embodiment, but the second
The subsequent pneumatic optical fiber feeding devices 33a and 33b include optical fiber storage containers 35a and 35b with open tops.
is the provision. These optical fiber storage containers 35a, 35
b are connected to the outlet ends of the narrow diameter pipes 15a and 15b, respectively, so that the compressed gas released from the outlet ends of the small diameter pipes exits into the atmosphere from above the optical fiber storage container. .

The optical fibers 11 fed into the narrow diameter conduit 15a by the first pneumatic fiber feeding device 13a are accumulated in the optical fiber storage container 35a. When the amount of optical fiber 11 accumulated is appropriate, the tip is passed through the gas seal part 21b of the pneumatic optical fiber feeding device 33a,
Compressed gas is pressurized from the compressed gas supply port 17b. Then, the optical fiber 11 is moved through the small diameter pipe 15 by the hydrodynamic force acting between it and the compressed gas flowing inside the small diameter pipe 15b.
It is sent into b.

At this time, since the outlet end of the small diameter conduit 15b is open in the optical fiber storage container 35b, a pressure difference at the large low exit is obtained, and accordingly, the optical fiber 11 is smoothly transferred to the small diameter conduit 15b. The optical fiber storage container 35b is reached. Thereafter, by repeating the same process, the optical fiber 11 can be fed into the small diameter pipe.

〔Effect of the invention〕

As explained above, according to the method of feeding an optical fiber into a small-diameter pipe according to the present invention, a long-distance small-diameter pipe is divided in the longitudinal direction, and the entrance end of each of the divided small-diameter pipes is Since a pneumatic optical fiber feeding device is connected to the tube and the outlet end is open, a sufficient flow rate of the compressed gas in each small-diameter pipe can be ensured at all times. Therefore, a continuous optical fiber can be easily fed into a long-distance narrow-diameter pipe without being restricted by the length of the small-diameter pipe. In addition, by using an optical fiber storage container for the second and subsequent pneumatic fiber feeding devices, even if the feeding speed of the optical fibers in each divided section is slightly uneven, it is possible to avoid undue tension on the optical fibers. A continuous optical fiber can be sent into a long-distance, small-diameter conduit divided into a plurality of parts without any stress.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing one embodiment of the method for feeding optical fiber into a long-distance narrow-diameter conduit according to the present invention, Figure 2 is a sectional view showing another embodiment of the same feeding method, and Figure 3 4 is a sectional view showing a conventional pneumatic optical fiber feeding device, and FIG. 4 is an explanatory diagram of a conventional optical fiber feeding method. 11: Optical fibers 13a, 13b, 13c: Pneumatic optical fiber feeder 15a, 15b, 15c:! fl diameter pipe line 17a, 1
7b, 17C: Compressed gas supply ports 19a, 19b, 19
c: Delivery mechanism 21a, 21b, 21c: Gas seal portion 31a, 31b: Outlet end of small diameter pipe line

Claims (1)

[Claims] 1. A long-distance narrow-diameter conduit in which a continuous optical fiber is installed is divided into a plurality of sections in the longitudinal direction, and a pneumatic light beam is installed at the entrance end of each divided narrow-diameter conduit. Light to a long-distance narrow-diameter conduit, characterized in that a fiber feeding device is connected, and the outlet end of each narrow-diameter conduit is left open, and a series of optical fibers are sequentially fed into the divided narrow-diameter conduits. Fiber feeding method. 2. The method according to claim 1, wherein the pneumatic optical fiber feeding device located between the narrow diameter pipes has an optical fiber storage container, and after the optical fiber is temporarily stored in the storage container, the optical fiber is sent out. A method for feeding an optical fiber into a long-distance, small-diameter conduit.