JP2951394B2 - Optical fiber feeding method to long distance small diameter pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method in which a continuous optical fiber is placed in a long-distance small-diameter pipe composed of a plurality of small-diameter pipes arranged so as to be continuous in the longitudinal direction. It is about the method of sending.

[Conventional technology and its problems]

As a method of feeding an optical fiber into a small-diameter pipe, there is a method in which compressed gas is sent from one end of the small-diameter pipe. As a conventional example of an apparatus for realizing this method, for example, the apparatus shown in FIG. 3 is known (Japanese Patent Laid-Open No. 59-104607).

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

The optical fiber 11 enters from the gas seal portion 21 and is sent out by the sending-out 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 becomes a small-diameter pipe.
The fluid is sent into the small-diameter conduit 15 by a hydrodynamic force acting between the compressed gas flowing through the inside 15 and the compressed gas flowing through the inside. At this time, the flow rate of the compressed gas flowing through the small-diameter pipe 15 needs to be faster than the sending speed of the optical fiber 11. However, since the frictional force between the compressed gas and the inner surface of the small-diameter pipe 15 acts on the compressed gas, when the pressure is constant, the flow velocity of the compressed gas becomes slower as the pipe length becomes longer. In some cases, the feeding speed cannot be secured. When the pipeline 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 of the pipeline. For this reason, in practice, there is a limit to the length of the optical fiber that is continuously fed.

In order to eliminate the limit of the feeding length described above,
As shown in (1), there has been proposed a method of supplying a compressed gas from the middle of a small-diameter pipe (Japanese Patent Laid-Open No. 1-292302). That is, in order to lay the optical fiber over a long distance, the supply ports 17a, 17b, 17c.
5 are provided at a plurality of locations at intervals in the longitudinal direction.
The supply of the compressed gas from the supply ports 17b, 17c,... Of 方法 is a method that starts after the optical fibers have passed through the supply ports.

However, in this method, since the small-diameter pipe 15 is continuous, the pressure difference between the entrance of the optical fiber and the portion to which the compressed gas is supplied from the middle becomes small, and the flow rate of the compressed gas during this period is slow. Thus, it was difficult to feed the optical fiber.

[Means for solving the problem and its operation]

The present invention provides a method for feeding an optical fiber to a long-distance small-diameter pipe, and the configuration is such that a long-distance thin-diameter pipe in which a continuous optical fiber is laid is divided into a plurality of pieces in the longitudinal direction. Each of the divided small-diameter pipes is connected to a pneumatic optical fiber feeding device at the inlet end, and the outlet end of each small-diameter pipe is opened, and one continuous line is sequentially connected to the separated small-diameter pipe. It is characterized by feeding an optical fiber.

The reason why the pneumatic optical fiber feeding device was connected to the inlet end of each of the divided small diameter pipes and the outlet end of each small diameter pipe was open was that the pressure between the inlet and the outlet for each section was This is because a difference can be obtained, the flow rate of the compressed gas is increased, and the optical fiber can be sent at a practically sufficient speed.

Also, a pneumatic optical fiber feeding device located between the small diameter pipes may be provided with an optical fiber storage container so that the optical fibers are temporarily stored therein and then sent out. Invention), even if the feeding speed in each section is somewhat uneven, a continuous optical fiber can be fed into a plurality of divided small-diameter conduits 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 a method for feeding an optical fiber into a long-distance small-diameter pipe according to the present invention.

A long-distance small-diameter pipe in which a continuous optical fiber 11 is laid is divided into a plurality of pieces in the longitudinal direction, and each of the divided small-diameter pipes is divided.
At the inlet ends of 15a, 15b, 15c... ‥, the same pneumatic optical fiber feeding devices 13a, 13b, 13c.
Are connected, and the outlet ends 31a, 31b,... Of each of the small-diameter pipes are open to the atmosphere.

The optical fiber 11 enters from the gas seal portion 21 and is sent out by the sending-out 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 becomes a small-diameter pipe.
The fluid is sent into the small-diameter conduit 15 by a hydrodynamic force acting between the compressed gas flowing through the inside 15 and the compressed gas flowing through the inside. Since the outlet end 31a of the small-diameter pipe 15a is open, the compressed gas is released into the atmosphere, and along with this, the optical fiber is smoothly fed into the small-diameter pipe 15a. It reaches the pneumatic optical fiber feeding device 13b. The optical fiber 11 reaches the second pneumatic optical fiber feeding device 13b and is fed into the small-diameter conduit 15b by the same operation as described above, and reaches the third pneumatic optical fiber feeding device 13c. . Thereafter, the same operation 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 is open, a pressure difference between the inlet and the outlet is obtained for each section, and the flow speed becomes equal in each section and the optical fiber is fed smoothly. Can be.

In this embodiment, an example is shown in which a gap is provided between the outlet end of the small diameter pipe and the pneumatic optical fiber feeding device to open the outlet end of the small diameter pipe. The form of opening the outlet end of the conduit is not limited to this.For example, the outlet end of the small-diameter conduit is connected to the next pneumatic optical fiber feeding device, and an exhaust hole is provided in the small-diameter conduit near the continuation portion. The same operation and effect as described above can be obtained even if compressed gas is released from the exhaust hole by providing an open structure.

FIG. 2 shows another embodiment of the method for feeding an optical fiber into a long-distance small-diameter pipe according to the present invention. Parts having the same functions as those in FIG. 1 are denoted by the same reference numerals.

In this embodiment, the first pneumatic optical fiber feeding device 13a uses the same one as in the above embodiment,
Subsequent pneumatic optical fiber feeding devices 33a and 33b are provided with optical fiber storage containers 35a and 35b whose upper parts are open. The optical fiber storage containers 35a and 35b are connected to the outlet ends of the small-diameter conduits 15a and 15b, respectively. It is designed to go inside.

The optical fiber 11 fed into the small-diameter pipe 15a by the first pneumatic optical fiber feeding device 13a is stored in the optical fiber storage container 35a. When the accumulated amount of the optical fiber 11 becomes appropriate, the tip of the optical fiber 11 is passed through the gas seal portion 21b of the pneumatic optical fiber feeding device 33a, and the compressed gas is injected from the compressed gas supply port 17b. Then, the optical fiber 11 is fed into the small-diameter pipe 15b by a hydrodynamic force acting between the optical fiber 11 and the compressed gas flowing in the small-diameter pipe 15b. At this time, the outlet end of the small-diameter conduit 15b is connected to the optical fiber storage container 35b.
The pressure difference between the inlet and the outlet is obtained because the optical fiber 11 is opened in
The light travels through b and reaches the optical fiber storage container 35b. Thereafter, by repeating the same, the optical fiber 11 can be fed into the small-diameter pipe.

〔The invention's effect〕

As described above, according to the method for feeding an optical fiber into a small-diameter conduit according to the present invention, the long-distance small-diameter conduit is divided in the longitudinal direction, and the entrance end of each divided small-diameter conduit is divided. Is connected to a pneumatic optical fiber feeding device, and the outlet end is open, so that the flow velocity of the compressed gas in each of the small-diameter pipes can always be ensured to be sufficient. For this reason, a continuous optical fiber can be easily fed into a long-distance small-diameter conduit without being restricted by the length of the small-diameter conduit. In addition, by using the second and subsequent pneumatic optical fiber feeding devices having an optical fiber storage container, even if the feeding speed of the optical fiber in each of the divided sections is somewhat irregular, excessive tension may be applied to the optical fiber. A continuous optical fiber can be fed into a plurality of divided long-distance small-diameter pipes without applying a pressure.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a method for feeding an optical fiber into a long-distance small-diameter pipe according to the present invention, FIG. 2 is a sectional view showing another embodiment of the feeding method, and FIG. FIG. 4 is a sectional view showing a conventional pneumatic optical fiber feeding device, and FIG. 4 is an explanatory view of a conventional optical fiber feeding method. 11: Optical fiber 13a, 13b, 13c: Pneumatic optical fiber feeding device 15a, 15b, 15c: Small-diameter pipe line 17a, 17b, 17c: Compressed gas supply port 19a, 19b, 19c: Delivery mechanism 21a, 21b, 21c: Gas seal part 31a, 31b: Outlet end of small diameter pipe 33a, 33b: Pneumatic optical fiber feeding device 35a, 35b: Optical fiber storage container

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G02B 6/00 H02G 1/08

Claims (2)

(57) [Claims] 1. A long-distance narrow-diameter pipe in which a continuous optical fiber is laid is divided into a plurality of sections in a longitudinal direction, and a pneumatic optical fiber feeding device is provided at an entrance end of each of the divided small-diameter pipes. , And an outlet end of each small-diameter pipe is opened, and a continuous optical fiber is sequentially fed into the divided small-diameter pipes, and an optical fiber feeding method to a long-distance small-diameter pipe is characterized in that: . 2. The method of claim 1, wherein the pneumatic fiber optic feeder located between the small diameter conduits has an optical fiber storage container in which the optical fiber is temporarily stored. A method for feeding an optical fiber into a long-distance small-diameter pipe, which is then sent out.