JPS59187137A - Towing cable - Google Patents

Abstract

PURPOSE:To facilitate to maintain the depth of an underwater sensor by changing the distribution of specific gravity of outer casing along the length of a cable in such a manner that the specific gravity of the cable end is smaller than that of the cable base so that the entering angle of the cable relative to the water surface may be large and the angle between the cable and the underwater sensor may be small. CONSTITUTION:The number of layers of the outer casing is made smaller in the direction of length toward the end so that the specific gravity of the cable end may be smaller than that of the cable base. Accordingly, the base area (a) of the cable 4 is the heaviest, and so the entering angle theta1 of the cable 4 relative to the water surface is large. On the other hand, the end area (c) is the lightest, and so, the angle formed by the cable 4 and an underwater sensor 3 becomes small. As the intermediate area (b) is lighter than the area (a) but heavier than the area (c), the cable takes a form of a mild curve. By this, even when the towing speed changes a little, the depth of the underwater sensor 3 will not change greatly.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to improvements in cables for towing underwater sensors.

(Prior technology) Cable for towing underwater sensor (hereinafter referred to as cable)
The cable has one or two layers of steel wire or aramid fiber as an exterior sheath around the signal line or power line, and the outer circumference is further protected with an external sheath such as polyethylene, but conventional cables have no part of the cable at all. The cross-sectional structure was the same, and the specific gravity distribution along the length of the cable was uniform.

When an underwater sensor is towed using such a conventional cable, the state of the cable becomes as shown in FIG.

That is, when the cable 2 is let out from the towing boat 1, the underwater sensor 3 is attached to the tip of the cable 2, and the towing boat 1 is sailing at a constant speed, the cable 2 becomes almost straight at the angle of incidence θl on the water surface. The underwater sensor 3 is waving almost horizontally at the depth. Note that the longitudinal direction of the cable 2 and the underwater sensor 3 form an angle θ2.

Now, if you increase the towing speed in this condition, cable 2
The lifting force acting on the underwater sensor 3 also increases, and the underwater sensor 3 floats up. Conversely, if the towing speed is reduced, the underwater sensor 3 will sink. Therefore, in order to maintain the underwater sensor 3 at a deep depth, the amount of cable 2 to be fed out must be adjusted each time in accordance with the towing speed, and there is a drawback that the amount of adjustment is large.

One possible solution to this drawback is to make the cable 2 heavier and increase the angle of incidence θ1 at which the cable 2 enters the water surface, but in this way the angle θ2 between the cable 2 and the underwater sensor 3 becomes larger. Therefore, the minute vibrations generated when the cable 2 cuts through the water are not directly transmitted to the underwater sensor 3, resulting in a disadvantage that the measurement accuracy of the underwater sensor 3 deteriorates.

(Objective of the Invention) An object of the present invention is to increase the angle of incidence of the cable with respect to the water surface and to reduce the angle formed between the cable and the underwater sensor.

(Structure of the Invention) In order to achieve the above object, the present invention has a structure in which the specific gravity of the cable tip is lighter than the specific gravity of the cable proximal end by changing the specific gravity distribution of the outer sheath along the length direction of the cable. It provides cables.

(Embodiment) FIG. 2 is a state diagram showing an embodiment of the present invention, and 4 is a cable in which the number of layers of armored wire is reduced along its length. This cable 4 has the heaviest portion a at the base end, and therefore the incident angle θl of the cable 4 with respect to the water surface is large.

Further, the 0 portion at the tip is the lightest, and therefore the angle formed by the cable 4 and the underwater sensor 3 is small. Since the middle part b is lighter than part a and heavier than part b, the cable 4 has a gently curved shape.

FIGS. 3(a), (b), and (c) are cross-sectional views showing each part of the embodiment shown in FIG.
) is a sectional view of part a, FIG. 3(b) is a sectional view of part b,
Figure (e) shows a sectional view of part 0. This figure 3 (a
) + In (b) and (c), 41 is the center conductor,
42 is an insulator, 43 is an outer conductor, 44 is an inner sheath, 4
5 is a first exterior layer formed of aramid fiber; 46
Reference numeral 47 indicates a second exterior layer formed of steel wire, 47 indicates a third exterior layer covering the second exterior layer, and 48 indicates an outer sheath having a low specific gravity such as polyethylene. Note that hatching is not applied to make it easier to see, but there are no voids.

Because of this structure, the cable 4 is heavy at part a and has a large incident angle θ1, and has a gentle slope at part b.
At part 0, it is nearly horizontal.

Figures 4 and gi: > 5 are explanatory diagrams comparing the effect of the above embodiment with the conventional example, and Figure 4 shows the relationship between the towing speed and the depth of the underwater sensor when the cable length is constant. FIG. 5 is a characteristic diagram showing the relationship between the cable length and the depth of the underwater sensor when the towing speed is constant. Further, in FIGS. 4 and 5, the solid line indicates the conventional side number, and the broken line indicates the present embodiment. Further, depth 0 means the water surface.

In Fig. 4, the depth of the underwater sensor changes greatly in response to changes in towing speed in the conventional system, whereas the depth of the underwater sensor in this embodiment does not change much even if the towing speed changes slightly. It shows that

In addition, Fig. 5 shows that when changing the depth of the underwater sensor, conventionally it was necessary to wind up and unwind a large amount of cable, but in this embodiment, the amount of winding or unwinding of this cable is small. It is shown that.

As explained above, in this embodiment, the number of layers of the outer wire, which has the highest specific gravity in the internal structure of the cable 4, gradually decreases from the towing boat 1 side toward the underwater sensor 3, and the specific gravity is large on the towing boat 1 side. , the specific gravity is smaller on the underwater sensor 3 side.

Therefore, the sea surface incidence angle θ3 of the cable 4 on the towing boat l side is large, and the angle formed by the underwater sensor 3 and the cable 4 is small. This makes it easier to maintain the depth of the underwater sensor 3 against fluctuations in towing speed, and also when changing the depth of the underwater sensor 3, the cable 4 is wound υ
In addition, the amount of vibration generated when the cable 4 drains from water is reduced, and the amount of vibration transmitted to the underwater sensor 3 is reduced.

Note that since the tension applied to the cable 4 gradually decreases from the towing boat 1 side toward the underwater sensor 3, no strength problem will occur even if the number of layers of the exterior is gradually reduced.

Further, the present invention is not limited to the above-described embodiments, and the same effect can be obtained by, for example, gradually reducing the number of sheathing wires along the length of the cable, or reducing the thickness of the sheathing wires.

Furthermore, when carrying out the present invention, it is desirable that the specific gravity of the cable near the underwater sensor 3 be approximately the same as that of the underwater sensor. This allows the underwater sensor and the cable to be connected in a substantially straight line, reducing vibrations of the underwater sensor. Specifically, since underwater sensors often have the same specific gravity as seawater, it is better to have the tip of the cable pull 4 close to the same specific gravity as seawater.

Furthermore, the specific gravity of the cables changed in three stages as shown in the example shown in Fig. 2, but also by thinning out the third layer of the exterior by one to several cables at each fixed distance. When the number is used up, the second exterior layer may be thinned out one to several pieces at a time to gradually reduce the number of pieces in multiple stages.

(Effects of the Invention) According to the present invention, the angle of incidence at which the cable enters the water is large, and at the connection part with the underwater sensor, the cape) and the underwater sensor form a straight line with an inclination angle close to the horizontal plane, so the underwater sensor The depth can be easily maintained, and even when the depth is changed, the amount of winding and unwinding of the cable is reduced, and the vibration transmitted to the underwater sensor is also reduced.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a towing state when a conventional towing cable is used, Fig. 2 is a schematic diagram showing a towing state when an embodiment of the present invention is used, Fig. 3(a), Φ) and (c) are sectional views showing the surface structure of each part of the embodiment shown in FIG. 2, and FIGS. 4 and 5 are characteristic diagrams comparing this embodiment and the conventional example. Figure 4 is a characteristic diagram showing the relationship between towing speed and underwater sensor depth when the cable length is constant, and Figure 5 is a characteristic diagram showing the relationship between cable length and underwater sensor depth when towing speed is constant. It is. DESCRIPTION OF SYMBOLS 1... Towing boat, 3... Underwater sensor, 4... Cable, 41... Center conductor, 42... Insulator, 43...
- External conductor, 44... Inner sheath, 45... Exterior first layer, 46... Exterior second layer, 47... Exterior third layer,
48...External sheath. Patent Applicant Yuki Omori Director of Technology Research Headquarters, Defense Agency Eioki Electric Industry Co., Ltd.

Claims (1)

[Claims] A towing cable for towing an underwater sensor, characterized in that at least one of the number of layers, the number, or the thickness of the outer wire having a large specific gravity gradually decreases toward the direction where the underwater sensor is connected.