JPH0425686Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a gas dam for an optical fiber cable that performs gas maintenance.

[Prior Art] As a maintenance method for optical fiber cables after installation, there is a gas maintenance method in which dry gas is sealed inside the cables, as in the case of copper cables. In order to carry out this method, it is necessary to provide a gas pipe 36 for introducing gas into the sheath 32 of the optical fiber 31 along with the optical fiber core 33, intervening cup 34, tension member 35, etc., as shown in FIG. There is.

Further, in order to maintain gas tightness at the end of the cable in one gas section, a gas dam (gas partition wall) as shown in FIG. 4 is provided. That is, the end portion 31 of the optical fiber cable 31 is placed inside the sleeve 37.
a is stored, and its insertion opening is a heat shrink tube 38.
shielded by. The gas pipe 36 of the cable 31 is connected to a gas valve 39 provided on the side of the sleeve 37, and the optical fiber core 33,
The intervening cup 34 and the tension member 35 are each guided to an end face 40 of the sleeve 37.

Further, an adhesive treatment 41 is applied to the outer periphery of the end portion 31a of the cable 31, and an adhesive resin 42 is filled in the sleeve 37 to maintain airtightness.

Then, gas maintenance is performed by supplying dry gas from the gas valve 39 to the gas pipe 36.

[Problems to be solved by the invention] As described above, conventionally, in order to perform gas maintenance, a gas pipe 36 is provided inside the optical fiber cable 31, and this gas pipe 36 is further connected to the gas valve 39 inside the sleeve 37 of the gas dam. I had to. Therefore, the optical fiber cable 31
The structure of the gas dam became complicated and the construction of the gas dam was difficult. Furthermore, there was a risk that the gas pipe 36 would come off from the gas valve 39 inside the sleeve 37.

Thus, an object of the present invention is to provide a gas dam for an optical fiber cable that eliminates the problems of the prior art described above, does not require a gas pipe, and is easy to construct.

[Means for Solving the Problems] In order to achieve the above object, the gas dam for optical fiber cable of the present invention has a seal at the insertion end of the optical fiber cable so as to surround the outer peripheral surface of the terminal end of the optical fiber cable. forming a gas supply chamber,
A gas valve is provided on the outer periphery of the gas supply chamber, and a gas introduction section is provided on the outer periphery of the optical fiber cable facing the gas supply chamber, with a portion of its coating removed.

[Function] With this configuration, the gas supplied from the gas valve into the gas supply chamber is introduced into the optical fiber cable via the gas introduction section, and gas maintenance is performed. In other words, there is no need for a gas pipe to introduce gas, and the construction of the gas dam becomes easier.

[Examples] Examples of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a partially cutaway perspective view of a gas dam for an optical fiber cable according to an embodiment of the present invention. The gas dam includes a sleeve 2 that seals and fixes the end of the optical fiber cable 1, and a gas supply chamber 3 connected to the end of the sleeve 2 on the insertion side of the optical fiber cable.
The terminal portion 5 of the optical fiber cable 1 is inserted into the connecting member 4 and the sleeve 2. Further, a gas valve 6 is provided on the outer periphery of the connecting member 4, and a gas introduction portion 7 whose coating is partially removed is provided on the outer periphery of the optical fiber cable 1 facing the gas supply chamber 3. It is configured such that gas can be introduced into the optical fiber cable 1 via the gas supply chamber 3 and the gas introduction section 7.

Such a gas dam is created as follows.

First, the end portion 5 of the optical fiber cable 1 is passed through the connecting member 4, and a portion of its coating is removed to form the gas introduction portion 7. The cable insertion port of the connecting member 4 is shielded with a heat shrinkable tube 8.

Furthermore, after applying adhesive treatment 9 to the outer circumference of the optical fiber cable 1 located at the end on the cable insertion side in the connection member 4, adhesive resin 10 is injected here to bond the optical fiber cable 1 and the connection member 4 together. Fix tightly. At this time, the cable end side of the connecting member 4 is made into a cavity, and the gas introduction part 7 of the optical fiber cable 1 is positioned in this cavity.
Then, a gas valve 6 is installed on the outer surface of the cavity of the connecting member 4.

Next, the end portion 5 of the optical fiber cable 1 is inserted into the sleeve 2, and as shown in FIG. 2, the sleeve 2 and the connecting member 4 are integrated with the O-ring 11 with a bolt. Furthermore, an adhesive treatment 12 is applied to the outer periphery of the end portion 5 of the optical fiber cable 1, and the optical fiber core 13, intervening cup 14, and tension member 15 in the optical fiber cable 1 are guided to the end surface 16 side of the sleeve 2. Then, the sleeve 2 is filled with adhesive resin 17 and sealed.

In the gas dam created in this way,
When gas is supplied from the gas valve 6 to the gas supply chamber 3, the gas further enters the inside of the optical fiber cable 1 through the gas introduction section 7, and gas maintenance is performed. Note that the gas-tightness of the optical fiber cable 1 is maintained by adhesive resins 10 and 17 and an O-ring 11.

Further, as the adhesive resins 10 and 17, urethane resin, foamed urethane resin, silicone resin, etc. can be used.

[Effects of the invention] As explained above, according to the present invention, the following excellent effects are achieved.

(1) Since a gas pipe is not used, the structure of the gas dam and optical fiber cable can be simplified, and the construction work of the gas dam can be facilitated.

(2) Compared to the conventional method of indirectly feeding gas into the cable through a gas pipe, gas is sent directly into the cable, improving efficiency.

[Brief explanation of the drawing]

1 and 2 are a partially cutaway perspective view and a sectional view of a gas dam for an optical fiber cable according to an embodiment of the present invention, respectively, and a sectional view of the vicinity of the gas supply chamber, and FIG. 3 shows the structure of a conventional optical fiber cable. The sectional view and FIG. 4 are partially cutaway perspective views of a conventional gas dam for an optical fiber cable. In the figure, 1 is an optical fiber cable, 2 is a sleeve, 3 is a gas supply chamber, 4 is a connecting member, 5 is an end portion, 6 is a gas valve, and 7 is a gas introduction portion.

Claims (1)

[Scope of utility model registration request] In a gas dam for an optical fiber cable that accommodates an end portion of an optical fiber cable and introduces gas supplied from a gas valve into the optical fiber cable, an outer circumferential surface of the end portion of the optical fiber cable is provided at the end portion on the insertion side of the optical fiber cable. A sealed gas supply chamber was formed to surround the gas supply chamber, the gas valve was provided on the outer periphery of the gas supply chamber, and a part of the coating was removed from the outer periphery of the optical fiber cable facing the gas supply chamber. A gas dam for optical fiber cable, characterized by having a gas introduction section.