JPH0529085B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides power supply to underwater equipment that is moved by remote control from the water, such as underwater robots or underwater observation equipment. The present invention relates to an optical fiber cable for underwater equipment suitable for supplying control signals.

[Summary of the invention]

The optical fiber cable for underwater equipment of the present invention has a structure in which the optical fiber cores, which are usually gathered in the center of the cable, are scattered around the periphery of the cable, so that even when the optical fiber cable is twisted, This is designed to reduce the tensile stress or compressive stress applied to the core wire.

Therefore, it is possible to prevent an increase in transmission loss or a disconnection accident due to cable twisting or the like.

[Conventional technology]

Cables that supply power and control signals to underwater robots, etc. are a mixture of optical fibers for communication and power lines for power supply, and these are insulated with appropriate tensile strength wires, sheaths, etc.・Constructed to be reinforced.

FIG. 3 shows an example of such a conventional optical fiber cable, in which a central tensile strength member 1 made of a wire rope or the like is arranged in the central part, and a plurality of optical fiber core wires 2 are spirally arranged around it. wrapped in a shape. After forming the buffer layer 3 with a suitable inclusion or elastomer, the outer periphery of the buffer layer 3 is covered with a sheath 4 made of plastic or the like to form an optical fiber unit 5.

A plurality of insulated power supply wires 6 are wound around the optical fiber unit 5 at a constant pitch, and a tensile strength member 7 made of multi-layered aramid fibers or the like is applied around the outer periphery, and a tensile strength member 7 made of a thermoplastic elastomer or the like is applied to the outer periphery. It covers the sheath 8 and constitutes an optical fiber cable.

[Problem that the invention seeks to solve]

By the way, when the optical fiber cable having the above-described structure is connected to an underwater robot or the like, a twisting force is applied due to the movement of the underwater robot. Then, the optical fiber core 2 placed in the center receives a tightening force from the power supply insulated wire 6 and the tensile strength member 7, and also receives tensile stress or compressive stress due to a change in the twist pitch of the optical fiber core 2. receive,
The transmission loss of the optical fiber increases, and in extreme cases, there is a risk that a disconnection accident will occur.

That is, as shown in FIG. 4a, the optical fiber core 2, which is wound around the central tensile strength member 1 with a twist pitch P ₀ and a core diameter D ₀ , is twisted twice within a length l. If the optical fiber core 2 has a length l, the effective length l _c0 of the optical fiber is l _c0 = 2√ ₀ ² + ( ₀ ) ²
When the layer is twisted once in the twisting direction, the twist pitch changes to P ₁ = 2/3P ₀ as shown in Fig. 4b, and if the layer core diameter does not change, then l' _c0 = 3√( 23 ₀ ) ² + ( ₀ ) ² .

Therefore, the elongation rate of the core wire El=l′ _c0 −l _c0 /l′ _c0 <
1 and will be subjected to tensile stress.

Also, if the twist acts in the opposite direction to the twisting direction, El
>1, and compressive stress is also applied.

Furthermore, due to such twisting, the layer core diameter of the optical fiber core wire 2 or the power supply insulated wire 6 is also expanded.
Otherwise, stress will be applied in the direction of shrinkage.

In this case, as shown in FIG. Since the core diameter of the optical fiber core 2 being twisted is subjected to stress in the direction of expansion, there is a large stress at the intersection of the optical fiber core 2 and the insulated wire 6 as shown by the arrow in FIG. 5b. There is a problem in that the pressing force is applied through the sheath 4, causing microbending of the optical fiber core 2.

In conventional optical fiber cables, as mentioned above, when the cable is twisted many times, various stresses act on the optical fiber core 2, increasing transmission loss and causing disconnection due to microbending. There was a drawback of doing so.

The present invention has been made to eliminate such drawbacks, and provides an optical fiber cable for underwater equipment that has a high degree of torsional resistance.

[Means for solving problems]

That is, the optical fiber cable for underwater equipment of the present invention has a tensile strength layer made of aramid fiber or the like, a reinforcing layer made of hard plastic or the like, and a reinforcement layer made of soft plastic or the like for each of the plurality of optical fiber core wires. A buffer layer is applied and reinforced optical fiber cords are scattered and gathered near the outer periphery of the cable.

[Effect]

Each fiber optic core is reinforced and protected by a tensile strength layer, a buffer layer, and a reinforcing layer, making it highly resistant to tension and compression. Since it is configured to be placed on the side,
Tightening stress from the outside is eliminated, and problems caused by twisting of the cable can be reduced.

〔Example〕

FIG. 1 shows the cross-sectional structure of an optical fiber cable for underwater equipment showing one embodiment of the present invention.
An inclusion 19 is disposed together with a filling 20, and its outer periphery is configured to bear the tensile strength of the cable by vertically lining a four-layer tensile strength member 17 made of aramid fibers (Kevlar), for example.

On the outside of the tensile strength body 17 is an insulated electric wire 16B for power supply.
A predetermined number of optical fiber cords 15 which have been reinforced and protected as will be described later are spirally wound at a constant pitch, and the gaps between them are filled with suitable inclusions.

A sheath 18 made of thermoplastic elastomer or the like is provided further outside.

FIG. 2 shows an enlarged sectional view of the optical fiber cord 15. A tensile strength layer 12 made of aramid fiber or the like is vertically formed around the optical fiber core 11, and a cushioning layer made of soft PVC is placed on top of this. The buffer layer 13 is made of plastic having a . Further, a reinforcing layer 14 made of hard polyamide plastic is formed on the outer periphery of the optical fiber cord 15.

Since the optical fiber cable for underwater equipment of the present invention has the above-described structure, even when the cable is twisted, the tensile stress applied to the optical fiber core 11 is absorbed by the buffer layer 13, and When compressive stress is applied to the optical fiber core wire 11, microbending can be prevented since the reinforcing layer 14 sets the optical fiber cord 5 to have high steel properties.

Furthermore, since the optical fiber cords 15 are scattered around the outer periphery of the cable, there is almost no tightening force from the outer periphery that would otherwise occur due to twisting, and even if compressive stress is applied, the optical fiber cords 15 There is an advantage that it becomes easy to diverge in a direction perpendicular to the length direction of the fiber cord 15 (particularly in the direction of the sheath 18).

FIG. 6 shows that an optical fiber cord having the structure of the embodiment of the present invention described above and a conventional optical fiber cable are twisted, and the change in transmission loss (dB) is plotted on the vertical axis, and the number of twists is plotted. This is data on the horizontal axis.

The twist was set to be 360 degrees per meter, and the twist direction was changed to rotate clockwise and counterclockwise every other turn.

As can be easily understood from this data diagram, the transmission loss of conventional optical fiber cables increases rapidly with each twist as shown by the dotted line, and breaks after about 10 twists, whereas the optical fiber of the present invention In the case of cables, as shown by the solid line, there is a remarkable effect that the transmission loss hardly changes even when twisted several tens to hundreds of times (not shown), and there is almost no mechanical failure. It will be done.

〔Effect of the invention〕

As explained above, in the optical fiber cable for underwater equipment of the present invention, the optical fiber core wire is processed into optical fiber cords, and these are scattered on the outside of the cable, so that the torsion resistance characteristics are significantly improved. This has the effect of making it possible to

Therefore, there is an advantage in that even when used in equipment that moves rapidly, such as underwater robots, there is almost no transmission failure, making it possible to conduct more advanced exploration activities, observation work, etc.

Furthermore, since each optical fiber cord is coated with a reinforcing coating, it is possible to directly connect these to an optical fiber connector or the like after terminal treatment, which has the advantage of simplifying the connection work.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the optical fiber cable for underwater equipment of the present invention, Fig. 2 is an enlarged sectional view of the optical fiber cord, Fig. 3 is a sectional view of a conventional optical fiber cable, and Fig. 4. Figures a and b are explanatory diagrams showing the elongation rate of the optical fiber when torsion is applied; FIG. 2 is a data diagram showing characteristic changes due to twisting of an optical fiber cable and a conventional optical fiber cable. In the figure, 11 is an optical fiber core wire, 12 is a tensile strength layer, 13 is a buffer layer, 14 is a reinforcing layer, 15 is an optical fiber cord, 16A, 16B are insulated electric wires for power supply,
17 is a tensile strength member, and 18 is a plastic sheath.

[Claims]

1 Manufacture of a waterproof optical cable that is made waterproof by storing a plurality of optical fiber cores or optical tape core wire laminates and powder of a water-absorbing swelling substance in a plurality of grooves spirally provided on the outer periphery of a rod-shaped spacer. In the method, the powder of the water-absorbing and swelling substance is supplied and charged by a conductive belt conveyor to which a voltage is applied, and a voltage having the same potential as the belt conveyor is applied to an inner side installed around the belt conveyor. A method for manufacturing a waterproof optical cable, characterized in that the powder is attached to an optical fiber core, an optical tape core laminate, or a rod-shaped spacer by electrostatic force through an opening in a cover made of an insulator seal having a conductor. . 2. The method of manufacturing a waterproof optical cable according to claim 1, wherein the powder of the water-absorbing and swelling substance is made of fibers of the water-absorbing and swelling substance. 3. The method for attaching the charged powder of water-absorbing and swelling material to the optical fiber core, optical tape core laminate, or rod-shaped spacer includes adhering the powder to the optical fiber core, optical tape core laminate, or rod-shaped spacer. The waterproof light case according to claim 1, characterized in that the waterproof light case is attached after the agent is applied.