JPS6248803B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a waterproof termination section for an optical fiber cable containing multi-core wires.

To prevent water droplets generated due to external temperature changes from flowing into communication cable lines, or from flowing into cables in adjacent sections when the cable is cut due to an accident, etc., underground and overhead lines are installed. Waterproof walls are often installed at ward boundaries and cable connections.

Conventionally, this type of waterproof wall has been made using a resin such as polyurethane or epoxy at the intermediate portion of the cable or the termination portion of the cable end.

FIG. 1 is a sectional view of an example of a conventional waterproof termination part using epoxy resin, in which 1 is an optical fiber cable, 2 is an optical fiber core, 3 is a dam sleeve, 4 is an epoxy resin, and 5 is an optical fiber cable. This is the connection between the dam sleeve and the cable jacket. Termination parts made using resin in this way have the characteristic that if the resin is injected into the liquid before it hardens, it will flow into the gap between the optical fiber cores and become fixed, so it can be easily manufactured.
As the number of cores increases, the distance between the cores becomes smaller, which makes it difficult to fill the gaps with resin, creating bubbles and voids, making it difficult to function as a waterproof wall. It was hot.

In the case of optical fiber cables, there is a problem in that the optical fiber core wire is mechanically weak and is therefore adversely affected by large expansion and contraction that occurs during resin curing or temperature changes.

Various ideas have been made to compensate for these shortcomings, but resins have the inherent problem that slight differences in injection conditions, curing conditions, etc. can easily cause large differences in the performance of the manufactured products. The drawback was that a stable and reliable waterproof wall could not be obtained.

In order to solve these drawbacks, the present invention constructs a waterproof wall by a mechanical method using rubber parts of a simple structure made uniformly in advance without using any resin. The object of the present invention is to obtain a uniform and highly reliable waterproof wall in an optical fiber cable containing multi-core wires without adversely affecting the optical fiber core wires. The present invention will be explained in detail below with reference to the drawings.

FIG. 2a is a cross-sectional view of an embodiment of the optical fiber cable waterproof termination part according to the present invention, and FIG.
is a cross-sectional view taken along line A-A', 6 is a rubber tube with a slit, 7 is a cylindrical member with a U-shaped groove, 8 is a sealing material, 9 is a rubber tube with an O-ring, 10 is a tightening ring, 11 is a presser metal fitting, 12
is an O-ring.

3 is a perspective view of parts of the rubber tube 6 with a slit in FIG. 2, 6-1 is a slit, FIG. 4 is a perspective view of a part of a cylindrical member with a U-shaped groove, and 7-1 is a U-shaped groove, FIG. 5 is a cross-sectional view of the parts of the rubber tube 9 with an O-ring,
9-1 is a nozzle part, and 9-2 is an O-ring part.

The inner diameter of the slitted rubber tube 6 is the same as or slightly smaller than the outer diameter of the optical fiber core 2, and when attached to the optical fiber core,
Expand the slit 6-1 and insert it into the fiber core. The suitable material for the slitted rubber tube 6 is vulcanized rubber such as ethylene propylene rubber, and the rubber hardness is 30 to 60 in order to provide waterproof function.
(JISA), dimensions are outer diameter 2~4mmφ, length 20~40mm
is appropriate.

The U-shaped grooved cylindrical member 7 may be made of rubber, plastic, metal, etc., and is made of a harder material than the slitted rubber tube 6. The size of the U-shaped groove is the same as or slightly smaller than the outer diameter of the slitted rubber tube, so that the slitted rubber tube can be inserted and held therein.

For this termination, a slitted rubber tube 6 is fitted into the optical fiber core 2, and the slitted rubber tube is fitted again into a cylindrical member with a U-shaped groove so that the slit is inside the U-shaped groove.
A structure that maintains airtightness between optical fiber cores by wrapping a sealing material 8 around the outer periphery, covering the outer periphery of the sealing material 8 with a rubber tube with an O-ring, and pressing the rubber tube with an O-ring from the outer periphery of the nozzle part with a tightening ring. It is becoming.

In the above structure, when inserting the slitted rubber tube 6 fitted into the optical fiber core into the U-shaped groove, the U-shaped groove must be lined with a thin layer of sealing material 8 in advance, or the outer periphery of the slitted rubber tube must be sealed. If you wrap the material 8 thinly and insert it into the U-shaped groove, the slitted rubber tube 6 and the U
The watertightness between the grooves is further improved.

Note that the inner diameter of the rubber tube with an O-ring is slightly smaller than the outer diameter when the sealing material is wrapped around it. Expand and cover. The material of the sealing material 8 is sticky soft rubber, and prevents gaps from forming between each member. The tube with the O-ring is made of the same material as the rubber tube with the slit, or a slightly softer rubber material is used. The material of the tightening ring may be rubber, plastic, or metal.

Next, an application example of the embodiment shown in FIG. 2 will be described.

FIG. 6 shows A in FIG. 2a of an embodiment of the termination section in which the core wires are accommodated in two layers in response to an increase in the number of core wires.
It is a sectional view corresponding to -A', and 13 is a U-shaped grooved sheet.

FIG. 7 is a perspective view of the parts of the U-shaped grooved seat. The U-shaped grooved sheet 13 has almost the same U-shaped groove and its material as the U-shaped grooved cylindrical member 7, and the sheet end face is bias-cut so that there is no step at the seam when the sheet is wound round. .

Next, FIG. 8 is a cross-sectional view corresponding to A-A' in FIG. 2a of an embodiment of a tape-shaped optical fiber, in which 14 is a tape-shaped optical fiber, 15 is a square rubber tube, and 16 is a square rubber tube. It is a cylindrical member with grooves.

9 is a perspective view of parts of the square rubber tube in FIG. 8, and FIG. 10 is a perspective view of parts of the square grooved cylindrical member used in FIG. 8.

Each has a shape that matches the tape-shaped optical fiber core wire. It is of course possible for this termination part to have a multilayer structure according to the number of core wires, as in FIG. 6.

As explained above, the optical fiber cable waterproof termination section of the present invention has the following advantages.

(1) A soft rubber tube is applied to the optical fiber core, and its length is short, about 20 to 40 mm, and it softly grasps the optical fiber core to maintain watertightness, so it does not adversely affect the properties of the optical fiber. do not have.

(2) The rubber tube that is fitted into the optical fiber core has a slit, and the rubber tube is fitted into the U-shaped groove of the cylindrical member with a U-shaped groove to achieve watertightness. Easy to assemble as there is no need to pass it through.

(3) The structure uses a pre-molded rubber tube and a cylindrical member with a U-shaped groove as watertight parts, and is assembled mechanically.
There is little variation in the performance of the finished product,
A uniform and highly reliable waterproof termination can be obtained.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a conventional waterproof termination, Figure 2a
2 is a sectional view of an embodiment of the optical fiber cable waterproof termination part according to the present invention, and FIG.
Sectional view at A', Figures 3, 4 and 5
The figures show the parts of the rubber tube with slit 6, the cylindrical member with U-shaped groove 7, and the rubber tube with O-ring 9 used in Fig. 2, respectively, and Fig. 6 shows the termination part accommodated in two layers corresponding to the core wires. 7 is a perspective view of the parts of the U-shaped grooved sheet used in FIG. 6, FIG. 8 is a sectional view of the embodiment of the termination part for the tape-shaped optical fiber core wire, and FIG. 9 is a sectional view of the embodiment. Figure and 1st
0 is a perspective view of the parts of the square rubber tube U-shaped grooved cylindrical member used in FIG. 8, respectively. DESCRIPTION OF SYMBOLS 1... Optical fiber cable, 2... Optical fiber core wire, 3... Dam sleeve, 4... Epoxy resin, 5... Cable jacket connection part, 6... Rubber tube with slit, 6-1... Slit, 7...
Cylindrical member with U-shaped groove, 7-1...U-shaped groove, 8
... Seal material, 9 ... Rubber tube with O-ring, 9-1 ... Nozzle part, 9-2 ... O-ring part, 10 ... Tightening ring, 11 ... Holding metal fitting,
12... O-ring, 13... U-shaped grooved sheet, 14... Tape-shaped optical fiber core, 15...
Square rubber tube, 16...Cylindrical member with square groove.

Claims (1)

[Scope of Claims] 1. A rubber tube having an inner diameter that is the same as or slightly smaller than the diameter of an optical fiber core, and in which a slit is provided at one location on the circumference formed by rolling it; and this rubber tube. It consists of a cylindrical member having a plurality of U-shaped grooves into which the cylindrical member can be inserted, and a soft rubber sealing material and a rubber tube with an O-ring placed on the outer periphery of the cylindrical member. A waterproof termination part for an optical fiber cable, characterized in that it is configured to be tightened with a ring.