Mooring line tension monitoring system

Abstract

To provide a tension monitoring system of a mooring rope capable of detecting a mooring post side tension of a mooring rope without using an elongation rate sensor.SOLUTION: A tension monitoring system 1 of a mooring rope according to one embodiment monitors the tension of a mooring rope 10 which is hung on at least one mooring hardware 22 on a hull 21 and the tip of which is moored to a mooring post 31 of a fixed structure 3. The tension monitoring system of the mooring rope includes a mooring machine 4 including a drum with the mooring rope 10 wrapped around it and a control device 9. The control device 9 calculates a drum side tension P of the mooring rope 10, determines a tension attenuation factor R due to the mooring rope 10 being spanned over at least one mooring hardware 22, and calculates the mooring post side tension P0 of the mooring rope 10 by multiplying the drum side tension P by the tension attenuation factor R, or by dividing the drum side tension P by the tension attenuation factor R.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to a mooring line tension monitoring system. [Background technology]

[0002] When mooring a vessel to a fixed structure such as a quay or offshore base, the mooring line is stretched across at least one mooring fitting on the hull, and the end of the mooring line is secured to a mooring post of the fixed structure. The mooring line is wound in and out by a mooring winch installed on the hull.

[0003] During mooring, the tension of the mooring line changes due to factors such as tide level, load, wind, and current, so it is desirable to monitor the tension of the mooring line. For example, Patent Document 1 describes a mooring machine that includes a drum around which the mooring line is wound, and a band brake that can be switched between a restrained state that prohibits the rotation of the drum and an open state that allows the rotation of the drum. When the band brake is in the restrained state, the tension of the mooring line is calculated from the detected value of a load cell provided on the band brake and the tension radius on the drum.

[0004] Furthermore, Patent Document 2 describes using a fiber rope as a mooring rope, twisting an elongation rate sensor into the tip of the fiber rope, and calculating the tension of the mooring rope from the value detected by the elongation rate sensor. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2002-211478 [Patent Document 2] International Publication No. 2020 / 110902 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] As described in Patent Document 1, when the tension of a mooring rope is calculated from the detected value of a load cell provided on a band brake and the tension radius on the drum, the calculated tension is the tension of the mooring rope in the vicinity of the drum. As mentioned above, since the mooring rope is stretched over at least one mooring fitting on the hull, the tension of the mooring rope differs before and after the mooring fitting. In other words, in the configuration described in Patent Document 1, it is not possible to detect the mooring post side tension, which is the tension of the mooring rope in the most important portion between the mooring fitting and the mooring post.

[0007] In contrast, the configuration described in Patent Document 2 can detect the tension of the mooring rope on the mooring post side, but it requires the elongation rate sensor to be twisted into the fiber rope.

[0008] Therefore, the present disclosure aims to provide a mooring line tension monitoring system that can detect the mooring line tension on the mooring post side without using an elongation rate sensor. [Means for solving the problem]

[0009] This disclosure provides a mooring line tension monitoring system for monitoring the tension of a mooring line stretched across at least one mooring fitting on a ship's hull and having its end secured to a mooring post of a fixed structure, comprising: a mooring machine including a drum around which the mooring line is wound; and a control device that calculates a drum-side tension, which is the tension in the portion of the mooring line between the mooring machine and the at least one mooring fitting; determines a tension attenuation rate due to the mooring line being stretched across the at least one mooring fitting; and calculates a mooring post-side tension, which is the tension in the portion of the mooring line between the at least one mooring fitting and the mooring post, by multiplying the drum-side tension by the tension attenuation rate or dividing the drum-side tension by the tension attenuation rate. [Effects of the Invention]

[0010] According to this disclosure, a mooring line tension monitoring system is provided that can detect the mooring line tension on the mooring post side without using an elongation rate sensor. [Brief explanation of the drawing]

[0011] [Figure 1] It is a schematic configuration diagram of a mooring cable tension monitoring system according to an embodiment. [Figure 2] It is a front view of a mooring machine. [Figure 3] It is a schematic configuration diagram of a band brake.

Mode for Carrying Out the Invention

[0012] Fig. 1 shows a mooring cable tension monitoring system 1 according to an embodiment. This mooring cable tension monitoring system 1 monitors the tension of the mooring cable 10 when the ship 2 is moored to a fixed structure 3 such as a quay wall or a marine base by the mooring cable 10.

[0013] Specifically, the mooring cable tension monitoring system 1 includes a plurality of mooring machines 4 provided on the hull 21 of the ship 2 and a control device 9 that controls these mooring machines 4. Each mooring machine 4 winds in and pays out the corresponding mooring cable 10. In this embodiment, four mooring machines 4 are arranged on the left and right sides of the bow and the left and right sides of the stern, but the number and position of the mooring machines 4 can be changed as appropriate.

[0014] A plurality of mooring fittings 22 are provided on the hull 21, and a plurality of mooring posts 31 are provided on the fixed structure 3. At the time of mooring, each mooring cable 10 is slung over at least one mooring fitting 22, and the tip of the mooring cable 10 is locked to the mooring post 31. In Fig. 1, all the mooring cables 10 are slung over two mooring fittings 22, but the number of mooring fittings 22 over which each mooring cable 10 is slung may be one or three or more.

[0015] The mooring hardware 22 is, for example, a stand roller, a fairleader, a deck roller, a chock, etc. The mooring post 31 is, for example, a bit, a bollard, a quick release hook, etc. The mooring cable 10 may be a fiber rope or a metal wire. Examples of the material of the fiber rope include nylon, high molecular weight polyethylene (HMPE), etc. The mooring cable 10 may have a tip portion made of a fiber rope and most of the remaining part made of a wire.

[0016] As shown in FIG. 2, each mooring device 4 includes a drum 7 around which the mooring cable 10 is wound and a motor 51 that rotates the drum 7. In FIG. 2, the drawing of the mooring cable 10 is omitted for simplicity of the drawing. The drum 7 is rotatably supported by a support base 25. In the present embodiment, a speed reducer 52 is provided between the motor 51 and the drum 7, and a clutch 53 and a band brake 6 are provided between the speed reducer 52 and the drum 7. That is, the motor 51 rotates the drum 7 via the speed reducer 52 and the clutch 53.

[0017] The motor 51 rotates in a first direction in which the mooring cable 10 is wound around the drum 7 and a second direction in which the mooring cable 10 is unwound from the drum 7. In the present embodiment, the motor 51 is a hydraulic motor, and the supply and discharge of hydraulic oil to the hydraulic motor are performed via a control valve 55. By controlling the control valve 55 by a control device 9, the stop, rotation in the first direction, and rotation in the second direction of the motor 51 are switched. However, the motor 51 may be an electric motor and directly controlled by the control device 9.

[0018] Furthermore, the motor 51 is provided with a torque detector 50 that detects the torque of the motor 51. In this embodiment, since the motor 51 is a hydraulic motor, a pressure sensor that measures the inflow pressure of the hydraulic fluid supplied to the hydraulic motor is used as the torque detector 50, and the inflow pressure measured by the pressure sensor is converted into the torque of the motor 51. However, instead of the pressure sensor, a torque sensor that directly measures the torque of the motor 51 may be used. Alternatively, if the motor 51 is an electric motor, the current flowing through the electric motor may be converted into torque.

[0019] The clutch 53 can be switched between a engaged state, which connects the drum 7 to the reduction gear 52, and a disengaged state, which disconnects the drum 7 from the reduction gear 52. In this embodiment, the clutch 53 includes a hydraulic cylinder. This hydraulic cylinder is connected to a solenoid valve 81, and the clutch 53 is switched from the engaged state to the disengaged state or vice versa by the control device 9 controlling the solenoid valve 81. However, the clutch 53 may include an electric cylinder instead of a hydraulic cylinder, and the electric cylinder may be directly controlled by the control device 9.

[0020] The band brake 6 can be switched between a restrained state that prohibits the rotation of the drum 7 and an open state that allows the rotation of the drum 7. In this embodiment, as shown in Figure 3, the band brake 6 includes a hydraulic cylinder 66. This hydraulic cylinder 66 is connected to a solenoid valve 82 (see Figure 2), and the solenoid valve 82 is controlled by the control device 9 to switch the band brake 6 from the restrained state to the open state or vice versa. However, the band brake 6 may include an electric cylinder instead of the hydraulic cylinder 66, and the electric cylinder may be directly controlled by the control device 9.

[0021] More specifically, the band brake 6 includes a brake drum 61 that rotates with the drum 7, and a pair of arc-shaped bands 62 and 63 that run along the brake drum 61. One end of the bands 62 and 63 are connected to each other via a pin 64, and the other ends of the bands 62 and 63 are connected to the aforementioned hydraulic cylinder 66 via a link mechanism 65. When the hydraulic cylinder 66 moves the other ends of the bands 62 and 63 apart via the link mechanism 65, a small gap is formed between the bands 62 and 63 and the brake drum 61, and the band brake 6 is released. Conversely, when the hydraulic cylinder 66 moves the other ends of the bands 62 and 63 closer together via the link mechanism 65, the bands 62 and 63 tighten around the brake drum 61, and the band brake 6 is restrained.

[0022] The band brake 6 is equipped with a load cell 60 that detects the band tension F acting on the bands 62 and 63 when they are restrained. In this embodiment, a pin-type load cell 60 is used. The link mechanism 65 includes a tension bar 67, which is connected to a bracket 23 provided on the hull 21 via the load cell 60.

[0023] The control device 9 receives an operation signal for each mooring machine 4. Based on the input operation signals, the control device 9 controls the control valve 55 and solenoid valves 81, 82 of the corresponding mooring machine 4. For example, since the control valve 55 includes an operation lever so that a crew member can manually operate the mooring machine 4, when the operation lever is tilted, an operation signal corresponding to the direction of tilt is input to the control device 9. Alternatively, if automatic operation is performed, the control device 9 may generate the operation signals itself.

[0024] With respect to the control device 9, the functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, dedicated processors, integrated circuits, ASICs (Application Specific Integrated Circuits), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuits. In this disclosure, a circuit, unit, or means is hardware that performs the enumerated functions, or hardware programmed to perform the enumerated functions. The hardware may be hardware disclosed herein, or other known hardware that is programmed or configured to perform the enumerated functions. If the hardware is a processor, which is considered a type of circuit, then the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and / or the processor.

[0025] Furthermore, the control device 9 is electrically connected to the torque detector 50 and load cell 60 described above. In this embodiment, the control device 9 is also electrically connected to the winding layer detector 70 and the two cameras 91 (see Figure 1). The winding layer detector 70 detects the number of winding layers of the mooring rope 10 on the drum 7. For example, the winding layer detector 70 converts the position of the outermost surface of the mooring rope 10 wound around the drum 7 into the number of winding layers.

[0026] One of the two cameras 91 photographs the area including the two mooring machines 4 located on the bow side and all the mooring hardware 22 through which the mooring lines 10 extending from these mooring machines 4 may be stretched, while the other camera 91 photographs the area including the two mooring machines 4 located on the stern side and all the mooring hardware 22 through which the mooring lines 10 extending from these mooring machines 4 may be stretched.

[0027] The control device 9 calculates the mooring column side tension P0, which is the tension in the portion of each mooring rope 10 between the mooring hardware 22 and the mooring column 31, based on the detection results of the torque detector 50, the load cell 60 and the winding layer detector 70, as well as the image from the camera 91.

[0028] First, the control device 9 calculates the drum-side tension P, which is the tension in the portion of each mooring rope 10 between the mooring machine 4 and the mooring hardware 22. Specifically, when the band brake 6 is in the open state, the control device 9 calculates the drum-side tension P based on the torque T of the motor 51 detected by the torque detector 50 and the number of windings N detected by the winding layer detector 70. For example, the control device 9 calculates the drum-side tension P using the following equation (1).

[0029]

number

[0030] Conversely, when the band brake 6 is in a restrained state, the control device 9 calculates the drum-side tension P based on the band tension F detected by the load cell 60 and the number of windings N detected by the winding layer detector 70. For example, the control device 9 calculates the drum-side tension P using the following equation (2).

[0031]

number

[0032] Next, the control device 9 determines the tension attenuation rate R for each mooring rope 10, which is caused by the mooring rope 10 being stretched over the mooring hardware 22. The image from the camera 91 is used to determine this tension attenuation rate R.

[0033] The control device 9 determines from the video captured by the camera 91 which mooring lines 10 are looped around which mooring fittings 22, and the winding angle of the mooring lines 10 with respect to each mooring fitting 22. Then, the control device 9 calculates an individual attenuation rate R i for each of the mooring fittings 22 around which the mooring lines 10 are looped. Here, "i" refers to the number of the mooring fitting 22 around which one mooring line 10 is looped. For example, the control device 9 calculates the individual attenuation rate R i using the following formula (3).

[0034]

Equation

[0035] The friction coefficient μ i is a coefficient corresponding to the type of the i-th mooring fitting 22 and the type of the mooring line 10 looped around the i-th mooring fitting 22. The control device 9 stores in advance a friction coefficient table defining the correspondence between the type of the mooring fitting 22 and the type of the mooring line 10 (material and diameter) and the friction coefficient. The control device 9 determines the friction coefficient μ of the i-th mooring fitting 22 using the friction coefficient table based on the type of the mooring line 10 stored in advance and the video of the camera 91. i For example, the friction coefficient table when the mooring fitting 22 is a chock is as shown in Table 1.

[0036]

Table 1

[0037] If there is only one mooring fitting 22 through which the mooring rope 10 is stretched, the control device 9 will control the individual attenuation rate R of that mooring fitting 22. i The tension attenuation rate R is determined as the tension attenuation rate R due to the mooring rope 10 being stretched over the mooring hardware 22. If there are multiple mooring hardware 22 through which the mooring rope 10 is stretched, the control device 9 determines the individual attenuation rate R of those mooring hardware 22. i The multiplier is then determined as the tension attenuation rate R due to the mooring rope 10 being stretched over the mooring hardware 22. In other words, the control device 9 determines the tension attenuation rate R of the entire mooring rope 10 using the following equation (4).

[0038]

number

[0039] Subsequently, when winding the mooring rope 10 onto the drum 7, the control device 9 calculates the mooring post side tension P0 by multiplying the drum side tension P by the tension attenuation rate R (P0 = P × R), and when unwinding the mooring rope 10 from the drum 7 and when the drum 7 stops, it calculates the mooring post side tension P0 by dividing the drum side tension P by the tension attenuation rate R (P0 = P ÷ R). Therefore, by simply switching whether to multiply or divide the drum side tension P by the tension attenuation rate R, it is possible to calculate the mooring post side tension P0 when winding the mooring rope and the mooring post side tension P0 when unwinding the mooring rope and when the drum stops.

[0040] As described above, in the mooring rope tension monitoring system 1 of this embodiment, the drum-side tension P is converted to the mooring post-side tension P0 using the tension attenuation rate R, so the mooring post-side tension P0 of the mooring rope 10 can be detected without using an elongation rate sensor.

[0041] Furthermore, in this embodiment, the tension damping rate R is determined using equation (4), so the individual damping rate R of each mooring hardware 22 i By simply calculating [a certain value], the overall tension attenuation rate R of the mooring line 10 can be calculated.

[0042] Furthermore, the individual damping rate R of each mooring fixture 22 i The coefficient of friction μ i and winding angle θ i Since it is calculated using the same formula, the individual attenuation ratio R i It is possible to calculate this.

[0043] (modified version) The present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention.

[0044] For example, instead of using a winding layer detector 70, a split drum including a storage drum and a tension drum may be used as the drum 7, and when mooring, the mooring rope 10 may be wound around the tension drum so that the radius from the center of the drum 7 to the line of action of the tension is constant. However, in this case, the work of winding the mooring rope 10 around the tension drum is required when mooring. In contrast, if the winding layer detector 70 detects the number of winding layers of the mooring rope 10 on the drum 7, special work during mooring, such as when using a split drum, is unnecessary.

[0045] Furthermore, depending on the vessel 2, the mooring hardware 22 to which the mooring rope 10 is passed may be predetermined. In this case, the camera 91 is unnecessary, and the control device 9 may store in advance the winding angles of the mooring rope 10 for each mooring hardware 22 other than the mooring hardware 22 located near the outline of the vessel 2.

[0046] Furthermore, with regard to the wrapping angle of the mooring rope 10 around the mooring fitting 22 located near the outline of the vessel 2, in other words, the mooring fitting 22 to which the mooring rope 10 is stretched, the control device 9 may calculate the wrapping angle of the mooring rope 10 around the mooring fitting 22 located closest to the mooring post 31 based on the GPS information (latitude and longitude) of the vessel 2, as well as the topographic information of the fixed structure 3 (including the latitude and longitude of the mooring post 31) that has been stored in the control device 9 in advance.

[0047] (summary) In a first aspect, the present disclosure provides a mooring line tension monitoring system for monitoring the tension of a mooring line stretched across at least one mooring fitting on a hull and having its end secured to a mooring post of a fixed structure, comprising: a mooring machine including a drum around which the mooring line is wound; and a control device that calculates a drum-side tension, which is the tension in the portion of the mooring line between the mooring machine and the at least one mooring fitting; determines a tension attenuation rate due to the mooring line being stretched across the at least one mooring fitting; and calculates a mooring post-side tension, which is the tension in the portion of the mooring line between the at least one mooring fitting and the mooring post, by multiplying the drum-side tension by the tension attenuation rate or dividing the drum-side tension by the tension attenuation rate.

[0048] With the above configuration, the tension on the drum side is converted to the tension on the mooring post side using the tension attenuation rate, so the tension on the mooring post side of the mooring rope can be detected without using an elongation rate sensor.

[0049] In a second embodiment, in the first embodiment, the at least one mooring device may include a plurality of mooring devices, and the control device may calculate an individual attenuation rate for each of the plurality of mooring devices and determine the tension attenuation rate due to the mooring rope being stretched over the plurality of mooring devices by multiplying the individual attenuation rates of the plurality of mooring devices. With this configuration, the tension attenuation rate of the entire mooring rope can be calculated by simply calculating the individual attenuation rate of each mooring device.

[0050] In a third embodiment, in the second embodiment, the control device may calculate the individual damping rate using the friction coefficient corresponding to the type of mooring rope and mooring hardware, and the wrapping angle of the mooring rope around the mooring hardware. With this configuration, the individual damping rate can be calculated using the same formula.

[0051] In a fourth embodiment, in any of the first to third embodiments, the control device may calculate the mooring post side tension by multiplying the drum side tension by the tension attenuation rate when winding the mooring rope onto the drum, and calculate the mooring post side tension by dividing the drum side tension by the tension attenuation rate when unwinding the mooring rope from the drum and when the drum is stopped. With this configuration, the mooring post side tension when winding the mooring rope and the mooring post side tension when unwinding the mooring rope and when the drum is stopped can be calculated simply by switching whether to multiply or divide the drum side tension by the tension attenuation rate.

[0052] In a fifth embodiment, in any of the first to fourth embodiments, for example, the mooring machine may include a motor for rotating the drum and a band brake that can be switched between a restrained state that prohibits the rotation of the drum and an open state that allows the rotation of the drum, and the control device may calculate the drum-side tension based on the torque of the motor when the band brake is in the open state, and calculate the drum-side tension based on the band tension of the band brake when the band brake is in the restrained state. [Explanation of Symbols]

[0053] 1. Mooring line tension monitoring system 10 Mooring lines 2 ships 21 Hull 22 Mooring hardware 4 Mooring machine 51. Motor (hydraulic motor or electric motor) 6-band brake 7 Drums 9 Control device

Claims

1. A system for monitoring the tension of a mooring rope that is stretched across at least one mooring device on the hull and whose end is secured to a mooring post of a fixed structure, A mooring machine including a drum around which the aforementioned mooring rope is wound, A control device that calculates the drum-side tension, which is the tension in the portion of the mooring rope between the mooring machine and the at least one mooring fitting, determines the tension attenuation rate due to the mooring rope being stretched over the at least one mooring fitting, and calculates the mooring post-side tension, which is the tension in the portion of the mooring rope between the at least one mooring fitting and the mooring post, by multiplying the drum-side tension by the tension attenuation rate or dividing the drum-side tension by the tension attenuation rate. A mooring line tension monitoring system equipped with the following features.

2. The aforementioned at least one mooring device includes a plurality of mooring devices, The mooring rope tension monitoring system according to claim 1, wherein the control device calculates an individual attenuation rate for each of the plurality of mooring fittings and determines the tension attenuation rate due to the mooring rope being stretched over the plurality of mooring fittings by multiplying the individual attenuation rates of the plurality of mooring fittings.

3. The mooring rope tension monitoring system according to claim 2, wherein the control device calculates the individual damping rate using the friction coefficient according to the type of mooring rope and mooring hardware and the wrapping angle of the mooring rope around the mooring hardware.

4. A mooring rope tension monitoring system according to any one of claims 1 to 3, wherein the control device calculates the mooring pole side tension by multiplying the drum side tension by the tension attenuation rate when the mooring rope is wound onto the drum, and calculates the mooring pole side tension by dividing the drum side tension by the tension attenuation rate when the mooring rope is unwound from the drum and when the drum is stopped.

5. The mooring machine includes a motor for rotating the drum and a band brake that can be switched between a restrained state that prohibits the rotation of the drum and an open state that allows the rotation of the drum. The mooring line tension monitoring system according to any one of claims 1 to 3, wherein the control device calculates the drum-side tension based on the torque of the motor when the band brake is in the open state, and calculates the drum-side tension based on the band tension of the band brake when the band brake is in the restrained state.

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