JPH0588410B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention is used for searching and catching cables, etc. laid on the bottom of the water or on the ocean floor using ropes suspended from a ship. The present invention relates to an underwater tension measuring device.

[Conventional technology] Conventionally, when searching for the location of a cable laid on the seabed or underwater, a search rope with a grapnel was hung from the exploration vessel and towed, and a load cell (tension measuring device) was installed on the vessel. The tension of the probe rope was measured during towing, and it was determined whether the grapnel had grasped the cable or not.

FIG. 5 schematically shows such a line-of-sight method, where S is a research ship exploring cable C from the sea, and R is a probe with a grapnel G connected to the tip to capture cable C. It is connected to a load cell M on the shipboard side with a wire rope.

When the exploration vessel S is operated at the point where the target cable C is laid, the grapnel G of the probe rope R being towed will be located at the cable C submerged on the seabed.
caught on. Then, since the tension applied to the search rope R increases, the onboard load cell M can detect that the grapnel G has gripped the cable C.

At this point, the cable C is pulled up, cut, or held while being pulled up and repaired.

[Problem that the invention seeks to solve]

However, a tensile force based on the underwater weight of the search rope R is always applied to the load cell on the ship. For example, in the case of a deep seabed, this underwater weight becomes extremely large, so the tensile force when catching the cable is There is a problem in that it becomes difficult to detect an increase in the load cell from the resolution of the load cell.

In particular, when varying tensions generated in the search rope due to waves, ocean currents, changes in ship speed, etc. are combined, it becomes extremely difficult to accurately detect cable information using a load cell on board.

The present invention was made in view of such problems, and relates to an underwater tension measuring device that can more accurately detect tension fluctuations during cable catching.

[Means for solving problems]

The casing has a pressure-resistant structure that houses a tension sensor with a bellows-type pressure balance mechanism between the grapnel and the probe rope, and an electric circuit to amplify the signal detected by the tension sensor and convert it into an appropriate signal. Join.

[Effect]

Tension fluctuations when the grapnel captures the target cable are detected by a tension sensor on the seabed or on the bottom of the water, and can be observed on board the ship via a signal line in the probe rope. Therefore, the influence of external tension fluctuations on the search rope is eliminated, and tension fluctuations during line tracking can be accurately detected.

〔Example〕

FIG. 1 shows a side view of the underwater tension device of the present invention, in which 1 is the tension sensor body, 2 is a watertight connector, and 3 is for amplifying the signal obtained from the tension sensor and converting it to a predetermined signal if necessary. 4 is a hook for locking the above-mentioned grapnel, etc.; 5 is a pressure-resistant protective casing that protects the tension sensor main body 1 and the circuit casing 3; 6; is a relief valve for water pressure balance, which will be described later.
7a and 7b are watertight bushes, 8 is a joint cylinder, 9 is a gimbal housing, and 10 is a bellows. Reference numeral 11a denotes a signal line outputted from the circuit case 3 via the watertight bushing 7a, and this signal line 11a is connected within the joint cylinder 8 to a signal line 11b inserted through the probe rope. . Reference numeral 12 indicates a tapered anchor that holds the tensile strength line of the search rope 14, and reference numeral 13 indicates a boot. Incidentally, as the grapnel to be secured to the hook 4, one having a cutting and holding function can be used.

FIG. 2 is a side view showing the inside of the tension sensor 1. Reference numeral 15 indicates screw holes 15a for locking the hooks 4 at both ends, and a probe rope connected through the joint cylinder 8, gimbal housing 9, and anchor 12. A center shaft 14 is provided with a screw hole 15b for locking a circuit housing flange 4a that transmits tension, and 16 is a strain gauge attached to the surface of the center shaft 15. For example, when the center shaft 15 is strained, Any electrical element may be used as long as it changes the impedance value when it occurs. Reference numeral 17 indicates silicone oil filled in the tension sensor 1, and reference numeral 18 indicates a bellows for balancing the external pressure and the internal pressure of the tension sensor and uniformizing the pressure applied to the strain gauge 16.

Since the underwater tension measuring device of the present invention has the above-described structure, when it is attached to the tip of the probe rope 14 and submerged to the bottom of the water or towed by a research vessel, A cable laid on the hook 4 is caught by a grapnel secured to the hook 4. Then hook 4
The electrical characteristics of the strain gauge 16 change as the tension applied to the strain gauge 16 increases and strain occurs in the central axis 15. This change characteristic is converted into an electric signal by an amplifier, a modulator, etc. provided inside the circuit case 3, and is transmitted to the observation device on the ship via the signal line in the search rope 14 via the signal lines 11a and 11b. be done.

Therefore, it is possible to accurately detect only the tension applied to the hook 4, and it is possible to accurately determine the state of the grapnel that has been caught, as seen in the data described below.

Fig. 3 is a graph showing tension fluctuation data obtained from a line-trapping experiment using a conventional load cell installed on a ship under the same conditions and a line-tracing experiment using the underwater tension measuring device of the present invention; B is the measurement data obtained by a conventional load cell.
The horizontal axis shows the time from sinking the search rope to catching the line, where T ₁ is the time when the grapnel landed on the seabed, T ₂ is the time when the cable was caught during the subsequent towing, and T ₃ is the time to catch the cable. Indicates the time the cable was cut after being caught.

As can be easily understood from this figure, the data obtained using the underwater tension measuring device of the present invention shows extremely low tension until the line is caught, and the tension increases rapidly at the moment the line is caught. Furthermore, amplitude fluctuations (noise) are extremely small and S/N is high compared to those using conventional load cells. Therefore, the resolving power is improved and landing time, line catching time, and cutting time can be detected very clearly.

FIG. 4 is a detailed side view of the relief valve 6 provided in the protective case 5, in which 19 is a relief valve cylinder, 20 is an automatic valve, and this automatic valve is connected to the cylinder 19 through an O-ring 20a. It is configured to slide with the Reference numeral 21 indicates a vertically long cut groove carved in the cylinder 19, and reference numeral 22 indicates an opening 2 fitted into one end of the cylinder 19.
A cap 2a is provided, and 23 is an aperture 23 which is also fitted into the other end of the cylinder 19.
A is the cap where it is installed.

This relief valve 6 is an automatic valve 20 when the water pressure increases when the underwater tension meter body is submerged in the sea.
moves to balance the internal pressure of the silicone oil filled inside the underwater tension meter body with the water pressure, increasing the pressure resistance of the protective casing, and at the same time, when abnormal water pressure is applied, it moves to the position indicated by the dotted line. The cut grooves 21 provide electrical continuity between the outside and the inside, thereby preventing accidents such as crushing of the protective casing 5.

Furthermore, even if seawater flows in, the tension sensor body is equipped with a bellows, so this double balance structure protects the inside of the expensive tension sensor from contamination and corrosion.
High accuracy can be maintained.

〔Effect of the invention〕

As explained above, by installing the underwater tension measuring device of the present invention between the probe rope and the grapnel, it is possible to search for cables with higher accuracy compared to the probe work using conventional load cells. It has the effect of
It has the advantage of being able to accurately measure tension on the ocean floor or under the seabed and perform cable trapping work.

[Brief explanation of drawings]

FIG. 1 is a side view of an underwater tension measuring device showing an embodiment of the present invention, FIG. 2 is a side view showing an example of a tension sensor, and FIG. 3 is a side view of an underwater tension measuring device of the present invention and a conventional load cell. Fig. 4 is a detailed side view of the relief valve, and Fig. 5 is an explanatory diagram of line catching work on the seabed or the bottom of the water. In the figure, 1 is the tension sensor body, 3 is the circuit case, 4
5 is a hook that locks the grapnel, 5 is a protective casing,
6 is a relief valve, 8 is a joint cylinder, 9 is a gimbal housing, 11a, 11b are signal lines,
Reference numeral 12 indicates an anchor, and reference numeral 14 indicates a search rope.

Claims (1)

[Claims] 1 Search lines for cables laid or buried at the bottom of the water,
Underwater tension measurement characterized in that, in an auxiliary line, a tension sensor equipped with a bellows-type pressure balance mechanism and a protective case containing a built-in circuit for amplifying the signal of the tension sensor are coupled between the grapnel and the probe rope. Device.