JPH0353607B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a submarine optical cable that simplifies the work of repairing a failed submarine optical cable and improves economic efficiency.

Figure 1 shows an example of the structure of a conventional submarine optical cable. In FIG. 1, 1 is a center support, 2 is an optical fiber core, 3 is a core buffer layer, 4 is an inner layer metal pipe, 5 is a tensile strength member, 6 is an outer layer metal pipe, 7,
8 indicates the outer covering. Generally, to produce an optical cable, a plurality of optical fibers 2 are assembled around a central support 1, a core buffer layer 3 is provided to protect this assembly from external forces, and inner and outer metal pipes 4 are provided. , 6, and undergoes various steps such as covering with an outer jacket. FIG. 2 is an enlarged view of the conventional submarine optical cable shown in FIG. 1, excluding the outer jacket. In this type of cable, since a plurality of tensile strength members 5 are assembled, there are small gaps between each of the tensile strength members 5. Furthermore, when polypropylene yarn is used as the cable core buffer layer 8, there are voids in the yarn, and even when silicone rubber or the like is used as the buffer layer 8, voids occur between the inner layer metal pipe 4 and the buffer layer 3, and once the cable When the cable is cut, seawater runs along the length of the cable, making it impossible to reuse it.

In addition, as an idea to have this water running prevention function,
A method of providing a waterproof dam part in a submarine optical cable having a single metal pipe is disclosed in Japanese Patent Application No. 127879/1983 (Japanese Patent Application No. 51704/1983), but a submarine optical cable having inner and outer layer metal pipes cannot be applied directly.

Figure 3 is a diagram explaining the water running mechanism of a conventional submarine optical cable, with arrows indicating the path of infiltrated water;
10 indicates a resin for preventing water running, and 10 indicates a failure point. resin 9
is filled into the gap between the tensile strength member 5 and the buffer layer 3, but if both filling points are shifted as shown in Figure 3, water will enter through pinholes or cracks caused by poor welding of the inner layer metal pipe 4, making it impossible to reuse the cable. There were flaws.

The present invention relates to a cable core consisting of a central support, an optical fiber core, and a core buffer layer constituting a submarine optical cable, an inner layer metal pipe with butted ends that protects this core from external forces, and a tensile strength member and an outer metal layer on the outer periphery of the pipe. In a submarine optical cable constructed by providing a pipe and covering it with a plastic outer insulator, all the gaps inside the outer layer metal pipe are filled with the following intermittently in the longitudinal direction of the cable:
The cable is also characterized by filling the same section with resin and providing a bulkhead to prevent water from entering the cable.
The purpose is to create a more economical line configuration than conventional cables by shortening the repair length of submarine optical cables.

FIG. 4 is a sectional view of a portion of the submarine optical cable of the present invention in which the gaps are filled with resins 9, 9', and the same parts as in FIG. 1 are designated by the same reference numerals. The submarine optical cable of the present invention shown in FIG. 4 is different from the conventional submarine optical cable shown in FIG. The difference is that the voids are completely filled with resin 9, 9'.

FIG. 5 is a diagram illustrating the water running prevention mechanism of the resin-filled submarine optical cable according to the present invention, showing the abutting portion of the inner layer metal pipe, the inside of the inner layer metal pipe 4, and the inner layer metal pipe 4 and the outer layer metal pipe 6.
Any filling that exists in between must be filled in the same interval. Note that the resin 9 filled inside the inner layer metal pipe 4 and the resin 9' filled between the inner layer metal pipe 4 and the outer layer metal pipe 6 may be of different types, but they must be materials that adhere to each other. . The arrow indicates the path of water that has entered from the failure point 10.

Next, embodiments according to the present invention will be described.

Example 1 A submarine optical cable structure shown in FIG. 4 was manufactured.
A 0.5 mm piano wire is used as the center support 1, 6 0.4 mm silicone coated fibers are assembled as the optical fiber core 2, and a Young's modulus of 0.3 is used as the core buffer layer 3.
Kg/mm ² silicone rubber is formed to a thickness of 0.6 mm, a core with an outer diameter of 2.5 mm is made, and an aluminum tape with a thickness of 1 mm is formed on this to make an outer diameter of 4.5 mm.
A cable was prototyped by providing a tensile strength member 5 and an outer layer metal pipe 6 formed by welding aluminum tape on its outer periphery. At this time, the trial length of the cable was 5 km, but the resin filling gaps 9 and 9' in Fig. 5 were set every 500 m, and the filling section length was approximately 5 m. The resins 9 and 9' used are applied to the inner and outer metal pipes by injecting a silicone adhesive from the gap between the tubes during the pipe forming process to bond between the core buffer layer 3 and the inner layer pipe 4 and between the tensile strength member 5 and the outer layer. The void in the pipe 6 was filled.

The fixing force of each part due to filling with adhesive is as follows:
After disassembly, the strength was measured and found to be approximately 2 kg. Applying 800 atm to one end of this 5km cable,
After leaving it for 2 weeks, cut it in 500m increments from the open end side.
As a result of checking for water leakage, there was no water leakage at 1 km from the pressure application point of the cable, but there was some water leakage at around 500 m. From this, it was found that the effect of the waterproof partition wall according to the present invention can be obtained by providing about two stages. In this example,
Although silicone resin was used, other resins such as urethane and acrylic may also be used.

Example 2 A cable having the same structure as the cable described in Example 1 was filled with a jewel-like resin without using an adhesive. The length of the filling section was approximately 10m, and the cable was filled intermittently every 100m, and a 3km cable was prototyped. A water pressure of 800 atmospheres was applied to one end of this cable, and as in the previous example, water leakage was investigated. As a result, jelly was accumulated at a location 2 km from the water pressure application point, and between 2 km from the water pressure application point. It was filled with water. In other words, it was found that even with a jelly-like filling material, water does not penetrate into the cable more than 2 km from the application point.

As explained above, the submarine optical cable of the present invention has two layers of metal pipes, and the inner metal pipes are butted to form a gap in the cable.
Both the inner and outer layers are filled with resin in the same section, so even if the submarine optical cable is cut under the seabed, the distance of seawater inundation can be kept to about 2 km, so the cable in the non-flooded sections can be reused. can.

Furthermore, when a faulty submarine optical cable is connected on board a ship, filling the entire length of the cable with adhesive resin will make it difficult to dismantle the cable required for the connection work, but as in the present invention,
If the filled section length is about 1/10 of the unfilled section length,
There is an advantage that this adhesive-filled section can be cut off during work inside the ship, and the connection work can be easily carried out in the non-filled section.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a conventional submarine optical cable, Figure 2
The figure is an enlarged view of the central part of Fig. 1, Fig. 3 is a diagram explaining the water running prevention mechanism of the conventional submarine optical cable, Fig. 4 is a cross-sectional view of the submarine optical cable of the present invention, and Fig. 5 is a diagram illustrating the water running prevention mechanism of the conventional submarine optical cable. FIG. 3 is a diagram illustrating a water running prevention mechanism of such a resin-filled submarine optical cable. 1... Central support, 2... Optical fiber core, 3
... Core buffer layer, 4 ... Inner layer metal pipe, 5 ...
Tensile strength member, 6...outer layer metal pipe, 7, 8...outer cover, 9, 9'...resin, 10...failure point.

Claims (1)

[Claims] 1. A cable core consisting of a central support, an optical fiber core, and a core buffer layer constituting a submarine optical cable, a butt-end-type inner layer metal pipe that protects this core from external forces, and a tensile strength on the outer periphery of this pipe. In a submarine optical cable consisting of a body and an outer layer metal pipe and covered with a plastic outer insulator, resin is applied intermittently in the longitudinal direction of the cable and in the same section in all the gaps inside the outer layer metal pipe. A submarine optical cable characterized by being filled with water and provided with a bulkhead to prevent water from entering the cable. 2 Silicone, urethane,
The submarine optical cable according to claim 1, characterized in that one type of acrylic is used.