Ships

Abstract

To provide a ship capable of holding at least a part of a deck in a target height position without using a friction force sensor.SOLUTION: A ship comprises a hull, a hydraulic cylinder, a deck connected via the hull and the hydraulic cylinder, a hydraulic pump constituting a closed circuit through connection to the hydraulic cylinder, a supporting capacity calculation unit to calculate the supporting capacity to support the deck using the hydraulic cylinder, and a flow control unit to adjust a flow rate of the hydraulic oil flowing in the circuit by controlling the hydraulic pump based on the supporting capacity. The flow control unit controls the flow rate so that the supporting capacity of the hydraulic cylinder approaches the preset standard weight as weight supported by the hydraulic cylinder.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to a ship.

Background Art

[0002] Conventionally, various multi-hull ships such as trimarans (three-hull ships) and catamarans (twin-hull ships) have been proposed as ships. For example, in Patent Document 1, there are at least two hulls (corresponding to hulls), a chassis part (corresponding to a deck) located above the two hulls, a suspension system capable of moving the two hulls with respect to the chassis part, a friction sensor, and a control system for controlling the suspension system. A ship (multi-hull ship) is disclosed. The friction sensor outputs a signal indicating the frictional force between an object (for example, a pylon) and the chassis part. The control system adjusts the support force between the chassis part and at least two hulls in order to reduce the frictional force in response to the input of the frictional force. Thereby, the relative movement between the object and the chassis part is minimized.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in Patent Document 1, a friction sensor (friction force input) is required to minimize the relative movement between the object and the chassis part and keep at least a part of the chassis part (for example, the bow) at the target height position, and there is room for improvement.

[0005] The present invention has been made to solve the above problems, and an object thereof is to provide a ship capable of keeping at least a part of a deck (for example, a bow) at a target height position without using a friction sensor. [Means for solving the problem]

[0006] A vessel according to one aspect of the present invention comprises a hull, a hydraulic cylinder, a deck connected to the hull via the hydraulic cylinder, a hydraulic pump connected to the hydraulic cylinder to form a closed circuit, a support force calculation unit that calculates the support force that the hydraulic cylinder provides to support the deck, and a flow rate control unit that controls the hydraulic pump based on the support force to adjust the flow rate of the hydraulic fluid flowing through the circuit, wherein the flow rate control unit adjusts the flow rate so that the support force of the hydraulic cylinder approaches a reference weight set in advance as the weight supported by the hydraulic cylinder. [Effects of the Invention]

[0007] With the above configuration, at least a portion of the deck can be kept at the target height position without using a friction force sensor. [Brief explanation of the drawing]

[0008] [Figure 1] This is a front view of a multi-hulled vessel, as an embodiment of the present invention, as seen from the front. [Figure 2] This is a perspective view of the above-mentioned multi-hulled ship, seen from the upper right front. [Figure 3] This is a side view of the above-mentioned multi-hulled vessel, seen from the right side. [Figure 4] This is a side view showing an enlarged view of the support mechanism located on the right front side of the above-mentioned multi-hulled vessel. [Figure 5] This is a side view showing the hydraulic cylinder of the above support mechanism in an extended state. [Figure 6] This is an explanatory diagram illustrating the forces that occur when the bow of the deck of the aforementioned multi-hulled vessel comes into contact with a pole installed on the base of an offshore structure. [Figure 7] This is a schematic diagram illustrating the configuration of the hydraulic circuit in the above-mentioned multi-hulled vessel. [Figure 8] This is a block diagram showing the schematic configuration of the control system installed in the above-mentioned multi-hulled vessel. [Figure 9] This flowchart shows the flow of operations due to bow-holding control in the above-mentioned multi-hulled vessel. [Figure 10] This is an explanatory diagram illustrating an example of the effects of the bow-holding control described above. [Figure 11] This is an explanatory diagram illustrating another example of the effects of the bow-holding control described above. [Figure 12] This is a schematic diagram illustrating the relationship between the hull of the above-mentioned multi-hulled vessel, the above-mentioned deck, and the reference height position of the above-mentioned deck. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below based on the drawings. In this specification, directions are defined as follows. First, the direction from the stern to the bow of a multi-hulled vessel is defined as "forward," and the direction from the bow to the stern is defined as "backward." The lateral direction perpendicular to the longitudinal direction is defined as the left-right direction. When the multi-hulled vessel is moving forward, the left side as seen from the perspective of the operator is defined as "left," and the right side as "right." Furthermore, the upstream side in the direction of gravity perpendicular to the longitudinal and left-right directions is defined as "up," and the downstream side is defined as "down." Vertical movement is also called ascending and descending. In the drawings, the forward direction is indicated by F, the aft direction by B, the left direction by L, the right direction by R, the upward direction by U, and the downward direction by D.

[0010] The multi-hull vessel of this embodiment can be used, for example, as a crew transfer vessel called a CTV (Crew Transfer Vessel). A CTV is a vessel used to transport workers, equipment, parts, etc., between land and offshore structures. For example, when performing maintenance on an offshore wind turbine used for offshore wind power generation, the structure in question could be the base of the offshore wind turbine. The multi-hull vessel of this embodiment is not limited to the above-mentioned CTV, and can also be used as a passenger ship, for example.

[0011] [1. Configuration of a multi-hulled ship] Fig. 1 is a front view of the multi-hull ship 1 of the present embodiment as seen from the front. Fig. 2 is a perspective view of the multi-hull ship 1 as seen from the upper right front. The multi-hull ship 1 includes a plurality of hulls 2, a deck 3, a support mechanism 4, and a main hull 5. A worker boarding the multi-hull ship 1 can enter a room inside the main hull 5 from the deck 3. The multi-hull ship 1 provided with the support mechanism 4 is also called a suspension boat.

[0012] In addition, in Figs. 1 and 2, for the convenience of explanation, the left hull 2 is lowered by the left and right support mechanisms 4 (the deck 3 is relatively raised with respect to the left hull 2), and the right hull 2 is raised (the deck 3 is relatively lowered with respect to the right hull 2). The raising and lowering of the deck 3 by such a support mechanism 4 is performed, for example, when the multi-hull ship 1 makes a right turn.

[0013] (1-1. Hull) The hull 2 is a longitudinally long float (hull) in the front-rear direction and is located one on each of the left and right sides of the main hull 5. Note that the number of hulls 2 is not limited to two, and may be three or more. That is, two or more hulls 2 may be located on each of the left and right sides of the main hull 5.

[0014] Fig. 3 is a side view of the multi-hull ship 1 as seen from the right side. In Fig. 3, for convenience, the illustration of the left hull 2 is omitted. Also, in the drawings after Fig. 3, for convenience, the illustration of the fence 3a of the deck 3 is omitted. An engine E is arranged inside the hull 2. By driving the engine E, a turbine (not shown) rotates and water flow is jetted into the sea. Thereby, the multi-hull ship 1 travels.

[0015] The hull 2 has an air intake and exhaust port 2a. The air intake and exhaust port 2a is located above the protruding portion 21. The protruding portion 21 protrudes upward from the rear end portion of the hull 2. The supply of air to the engine E and the exhaust from the engine E are performed through the air intake and exhaust port 2a located behind the engine E.

[0016] Inside Hull 2, in addition to Engine E, a hydraulic pump HP is also located. The hydraulic pump HP is connected to hydraulic hoses 46a and 46b (see Figures 4 and 5), which will be described later.

[0017] (1-2. Deck) The deck 3 shown in Figures 1 to 3 is a deck located above the multiple hulls 2 and the main hull 5. The deck 3 is connected to each of the multiple hulls 2 via the hydraulic cylinders 41 of the support mechanism 4, which will be described later. The main hull 5 is located below the deck 3 and is connected to the deck 3.

[0018] As shown in Figure 1, deck 3 has an upper plate section 31 and a frame structure section 32. The frame structure section 32 is formed in a grid pattern and constitutes the framework of the upper plate section 31. The upper part of the frame structure section 32 is covered by the upper plate section 31. On the other hand, the frame structure section 32 is exposed downwards. This reduces the weight of deck 3, and consequently the weight of the multi-hull vessel 1.

[0019] At both ends of the deck 3 in the left-right direction, fences 3a (see Figures 1 and 2) are installed extending in the front-to-back direction. The fences 3a are installed to prevent workers from falling from the deck 3.

[0020] A cockpit 3c is provided on deck 3. Inside the cockpit 3c, at the front, is the control unit 3c1 (see Figure 3). The control unit 3c1 is located approximately in the center of deck 3. The operator controls the multi-hulled vessel 1 by operating levers, handles, various switches, etc., in the control unit 3c1.

[0021] (1-3.Support mechanism) The support mechanism 4 shown in Figures 1 to 3 supports the deck 3 on multiple hulls 2 and is a mechanism that raises and lowers each of the multiple hulls 2 relative to the deck 3. In this embodiment, two support mechanisms 4 are provided for each of the left and right hulls 2. More specifically, one support mechanism 4 is provided on the front upper and rear upper parts of the right hull 2, and one support mechanism 4 is provided on the front upper and rear upper parts of the left hull 2. Each support mechanism 4 has a hydraulic cylinder 41.

[0022] Figure 4 is an enlarged side view showing the support mechanism 4 located on the front right side. The hydraulic cylinder 41 is a telescopic member that extends and retracts in one direction and includes a piston rod 412 that moves by hydraulic pressure. One end 41a of the hydraulic cylinder 41 in the extension and retraction direction is connected to the upper surface 2S of the hull 2. The upper surface 2S of the hull 2 ​​here refers to the upper surface of the hull 2 ​​when the protruding portion 21 (see Figures 2 and 3) is removed from the hull 2. The upper surface 2S is a nearly flat surface. On the other hand, the other end 41b of the hydraulic cylinder 41 in the extension and retraction direction is directly supported on the lower surface of the deck 3.

[0023] The hydraulic cylinders 41 described above are provided in each of the four support mechanisms 4. In other words, the multi-hull vessel 1 of this embodiment is equipped with multiple hydraulic cylinders 41.

[0024] The multi-hull vessel 1 of this embodiment has a link mechanism (not shown). The link mechanism is provided corresponding to each of the left and right hulls 2 and connects the hulls 2 to the deck 3. Each link mechanism is provided to prevent the deck 3 from tilting forward or backward relative to the hull 2 ​​as each hydraulic cylinder 41 extends or retracts.

[0025] [2. Details of the support mechanism] Next, we will explain the details of the support mechanism 4 described above. For convenience, we will explain the details of the support mechanism 4 located on the front right side, as shown in Figure 4. However, since the basic configuration of the support mechanisms 4 located on the rear right side, front left side, and rear left side is the same, we will omit their explanation.

[0026] The hydraulic cylinder 41 of the support mechanism 4 comprises a cylinder tube 411 and a piston rod 412. The cylinder tube 411 is a cylindrical cover that houses the piston rod 412. The rear end (lower end) of the cylinder tube 411 is rotatably connected to the upper surface 2S of the hull 2 ​​via a first bracket 44. The piston rod 412 moves hydraulically relative to the cylinder tube 411. The tip (upper end) of the piston rod 412 is rotatably connected to and supported by the lower surface of the deck 3 via a second bracket 45. The rear end (lower end) of the piston rod 412 is located inside the cylinder tube 411.

[0027] The support mechanism 4 also has two hydraulic hoses 46a and 46b. One end of hydraulic hose 46a is connected to the upper end of the cylinder tube 411, and the other end is connected to the hydraulic pump HP (see Figure 3) inside the hull 2. On the other hand, one end of hydraulic hose 46b is connected to the lower end of the cylinder tube 411, and the other end is connected to the hydraulic pump HP inside the hull 2.

[0028] By controlling the supply of hydraulic pressure from the hydraulic pump HP to the cylinder tube 411, the piston rod 412 can be extended and retracted relative to the cylinder tube 411. In other words, the hydraulic cylinder 41 can be extended and retracted in the axial direction of the piston rod 412. More details are as follows. The control of the supply of hydraulic pressure to the cylinder tube 411 (control of the hydraulic pump HP) is performed by the flow control unit 72 (see Figure 8), which will be described later.

[0029] Figure 5 is a side view showing the hydraulic cylinder 41 in an extended state. For example, by supplying hydraulic fluid from a hydraulic pump HP to the lower part of the cylinder tube 411 via a hydraulic hose 46b, while simultaneously discharging hydraulic fluid from the upper part of the cylinder tube 411 via a hydraulic hose 46a, the piston rod 412 can be pushed out of the cylinder tube 411, that is, the hydraulic cylinder 41 can be extended, as shown in Figure 5.

[0030] Conversely, by supplying hydraulic fluid from the hydraulic pump HP to the upper part of the cylinder tube 411 via the hydraulic hose 46a, while simultaneously discharging the hydraulic fluid from the lower part of the cylinder tube 411 via the hydraulic hose 46b, the piston rod 412 can be retracted into the cylinder tube 411, as shown in Figure 4, that is, the hydraulic cylinder 41 can be retracted.

[0031] In this way, each hydraulic pump HP can adjust the relative distance (height position) of the deck 3 relative to the hull 2 ​​by extending and retracting each hydraulic cylinder 41. For example, by retracting each hydraulic cylinder 41, the deck 3 can be lowered, that is, the deck 3 can be brought closer to the hull 2. Conversely, by extending each hydraulic cylinder 41, the deck 3 can be raised, that is, the deck 3 can be moved away from the hull 2. Therefore, when workers board or disembark between a pier or offshore structure and the multi-hull vessel 1, the supply of hydraulic pressure to each hydraulic cylinder 41 can be appropriately controlled by the flow control unit 72, and by appropriately controlling the extension and retraction of each hydraulic cylinder 41, the height position of the deck 3 can be adjusted to match the position of the pier, etc., enabling smooth and safe boarding and disembarking of workers.

[0032] Furthermore, when the multi-hull vessel 1 is traveling in a right turn, as shown in Figure 1, by retracting the two front and rear hydraulic cylinders 41 connected to the right hull 2 ​​and extending the two front and rear hydraulic cylinders 41 connected to the left hull 2, the left side of the deck 3 is raised higher than the right side, making it less likely for the multi-hull vessel 1 to capsize due to rolling to the left. Conversely, by extending the two front and rear hydraulic cylinders 41 connected to the left hull 2 ​​and retracting the two front and rear hydraulic cylinders 41 connected to the right hull 2, the right side of the deck 3 is raised higher than the left side, making it less likely for the multi-hull vessel 1 to capsize due to rolling to the right.

[0033] [3. Regarding bow-holding control] In this embodiment, the front end of the deck 3 (hereinafter also referred to as the bow) is brought into contact with the base of the offshore wind turbine, and when crew members board or disembark between the deck 3 and the base, bow-holding control is performed to minimize the relative movement between the base and the deck 3 without using a friction force sensor.

[0034] (3-1. Principles of bow-holding control) First, the principle of bow-holding control in this embodiment will be explained. Figure 6 shows the forces generated when the bow of the deck 3 is in contact with the pole PO provided on the base. In the figure, the black circle indicates the contact point between the deck 3 and the pole PO. For convenience, in Figure 6, the contact point is shown separated from the pole PO. Wd represents the weight (N) of the deck 3, and Wh represents the weight (N) of the hull 2. S represents the force (N) acting from the hydraulic cylinder 41 on the deck 3 and the hull 2. B represents the buoyancy (N) acting on the hull 2, and T represents the thrust (N) acting on the hull 2. V represents the normal force (N) acting from the pole PO on the deck 3, and F represents the frictional force (N). WS is the water surface. In this figure, it is assumed that the deck 3 moves in the Z direction and the frictional force acts in the -Z direction. The positive direction of the Z direction is the downward direction in the vertical direction.

[0035] For deck 3, the equation of motion in the Z direction is given by equation (1) below. Md × a = Wd - SF ... (1) Here, Md represents the mass of deck 3 (kg), and a is the acceleration of deck 3 (m / s²). 2 This shows that when the elastic force of the hydraulic cylinder 41 (corresponding to S above) is equal to the weight Wd of the deck 3, the following equation (2) holds. Md × a = -F ···(2)

[0036] Since friction acts as a damping force, acceleration a converges to zero. In other words, deck 3 comes to rest, and the relative motion between pole PO and deck 3 is minimized. At this time, if the number of support points on deck 3, i.e., the number of hydraulic cylinders 41, is n, then the support force of one hydraulic cylinder 41 supporting deck 3 is Wd / n (equivalent to the supported weight). In other words, by controlling the hydraulic pump HP so that the support force of each hydraulic cylinder 41 approaches Wd / n, and adjusting the hydraulic pressure (flow rate of hydraulic fluid) supplied to each hydraulic cylinder 41, the relative motion between pole PO and deck 3 can be minimized without using a friction force sensor.

[0037] (3-2. Regarding hydraulic circuits) The multi-hull vessel 1 of this embodiment is configured to include the hydraulic circuit shown in Figure 7 in order to achieve the bow-holding control described above. Figure 7 schematically shows the configuration of the hydraulic circuit including the hydraulic pump HP installed inside the right hull 2 ​​in the multi-hull vessel 1 of this embodiment. Note that the configuration of the hydraulic circuit including the hydraulic pump HP installed inside the left hull 2 ​​is the same as the hydraulic circuit on the right side, so its explanation is omitted here.

[0038] In Figure 7, "FR" indicates the front right and "RR" indicates the rear right. The dashed arrows indicate output signals. Of the two hydraulic cylinders 41 connected to the hull 2, the hydraulic cylinder 41 connected to the front of the hull 2 ​​is shown as the front hydraulic cylinder 41F, and the hydraulic cylinder 41 connected to the rear of the hull 2 ​​is shown as the rear hydraulic cylinder 41R.

[0039] Inside the hull 2, two hydraulic pumps HP are provided, corresponding to the hydraulic cylinders 41 located at the front right and rear right. Each hydraulic pump HP is a variable displacement pump and is driven by power transmitted from the engine E. Each hydraulic pump HP is connected to the hydraulic cylinder 41 via the hydraulic hoses 46a and 46b described above, forming a closed circuit through which hydraulic fluid flows. In other words, the multi-hull vessel 1 is equipped with hydraulic pumps HP that are connected to the hydraulic cylinders 41 to form a closed circuit. In Figure 7, of the two hydraulic pumps HP, the one that supplies hydraulic fluid to the front hydraulic cylinder 41F is shown as front hydraulic pump HP1, and the one that supplies hydraulic fluid to the rear hydraulic cylinder 41R is shown as rear hydraulic pump HP2.

[0040] The closed circuit described above is provided with a pressure detection unit 61. The pressure detection unit 61 detects the pressure that changes in accordance with the external force applied to the hydraulic cylinder 41 when an external force in the expansion / contraction direction is applied to the hydraulic cylinder 41. In other words, the multi-hull vessel 1 is equipped with the pressure detection unit 61 described above, which is provided in the closed circuit. The pressure detection unit 61 is composed of, for example, a pressure sensor. The closed circuit is provided with an accumulator (not shown) that stores hydraulic fluid, and the pressure detection unit 61 detects the pressure (hydraulic pressure) of the hydraulic fluid stored in the accumulator. The detection signal of the pressure (accumulator pressure) detected by the pressure detection unit 61 is output to the control device 70.

[0041] Figure 8 is a block diagram showing the schematic configuration of the control device 70. The control device 70 is composed of a central processing unit called a CPU (Central Processing Unit), for example, and controls the operation of each part of the hull vessel 1. In particular, the control device 70 includes the functions of a bearing capacity calculation unit 71 and a flow rate control unit 72. That is, the hull vessel 1 includes a bearing capacity calculation unit 71 and a flow rate control unit 72.

[0042] The support force calculation unit 71 calculates the support force that the hydraulic cylinder 41 provides to the deck 3 based on the pressure detected by the pressure detection unit 61. The flow rate control unit 72 controls the hydraulic pump HP based on the support force calculated by the support force calculation unit 71 to adjust the flow rate of the hydraulic fluid flowing through the closed circuit.

[0043] Furthermore, the multi-hulled vessel 1 of this embodiment is equipped with a height detection device 80. The height detection device 80 detects the height position of the deck 3. Such a height detection device 80 is composed of, for example, an inertial measurement unit (IMU) including an acceleration sensor. The height can be determined by performing a second integral of the vertical acceleration detected by the acceleration sensor. The height detection devices 80 are provided at the four corners of the deck 3 (front right, rear right, front left, and rear left). The flow control unit 72 can set a target height position H0 (see Figure 10) for bringing the bow of the deck 3 into contact with the pole PO based on the height position of the deck 3 detected at each height detection position 80, but the details of this will be described later.

[0044] (3-3. Operation by bow-holding control) Figure 9 is a flowchart showing the operation flow by the bow-holding control in this embodiment. The above operation will be described below.

[0045] First, a reference weight Wref(N) is set in advance (S1) for which the hydraulic cylinders 41 support the deck 3. This reference weight Wref is the value obtained by dividing the weight Wd(N) of the deck 3 by the total number n (units) of hydraulic cylinders 41. In this embodiment, the total number of hydraulic cylinders 41 is 4 (two front and rear for the right hull 2, and two front and rear for the left hull 2, for a total of 4), so Wref = Wd / n = Wd / 4.

[0046] When the bow of the deck 3 is in contact with an offshore structure (for example, a pole installed on the base of an offshore wind turbine) to maintain a stationary position, if the hull 2 ​​rises due to the rising of the water surface and approaches the deck 3, the hydraulic cylinder 41 receives an external force in the contraction direction. In this case, the pressure (accumulator pressure) detected by the pressure detection unit 61 increases. Conversely, if the hull 2 ​​descends due to the falling of the water surface and moves away from the deck 3, the hydraulic cylinder 41 receives an external force in the extension direction. In this case, the accumulator pressure detected by the pressure detection unit 61 decreases. In either case, the accumulator pressure detected by the pressure detection unit 61 is input to the control device 70 (S2). In this embodiment, the accumulator pressure is input to the control device 70 from four pressure detection units 61, each corresponding to one of the four hydraulic cylinders 41.

[0047] Then, the support force calculation unit 71 of the control device 70 calculates the support force S that the hydraulic cylinders 41 support the deck 3 based on the pressure detected by the pressure detection unit 61 corresponding to each hydraulic cylinder 41 (S3). Specifically, the accumulator pressure detected by the pressure detection unit 61 is P (MPa), and the cylinder area of ​​the hydraulic cylinder 41 (bottom area of ​​the cylinder tube 411) is Cs (cm²). 2 Assuming that the bearing force of the hydraulic cylinder 41 is S(N), the bearing force calculation unit 71 calculates the bearing force S from the following equation (3). S = P × Cs × 10 -2 ...(3)

[0048] In S3, the support force calculation unit 71 may calculate the support force S (also referred to as support force SF) that each front hydraulic cylinder 41F supports the deck 3 based on the pressure detected by the pressure detection unit 61 corresponding to at least two front hydraulic cylinders 41F located on the left and right among the four hydraulic cylinders 41. Therefore, in S3, it is not always necessary for the support force calculation unit 71 to calculate the support force S (also referred to as support force SR) that each rear hydraulic cylinder 41R supports the deck 3 based on the pressure detected by the pressure detection unit 61 corresponding to the two rear hydraulic cylinders 41R located on the left and right among the four hydraulic cylinders 41. However, in terms of also performing the position control (attitude control) of the deck 3 described later, in S3, in addition to the support force SF, it is desirable to calculate the support force SR. Hereinafter, it is assumed that the support force S includes both the above-mentioned support force SF and support force SR.

[0049] The flow rate control unit 72 calculates the deviation D (N) between the support force S calculated in S3 and the reference weight Wref set in S1 (S4). That is, the deviation D is the absolute value of the difference between the support force S and the reference weight Wref. Then, the flow rate control unit 72 determines whether the deviation D calculated in S4 is greater than or equal to the threshold value Dth (S5). In S5, when the deviation D is less than the threshold value Dth (No in S5), the flow rate control unit 72 does not perform the following hydraulic oil flow rate correction control (flow rate operation) and waits. That is, when the deviation D satisfies 0 ≦ D < Dth, the flow rate operation is not performed. Therefore, this range can also be called the "dead zone" where the flow rate operation is not performed.

[0050] On the other hand, in S5, when the deviation D is greater than or equal to the threshold value Dth (Yes in S5), the flow rate control unit 72 performs the following hydraulic oil flow rate correction control. That is, the flow rate control unit 72 adjusts the flow rate of the hydraulic oil flowing through the closed circuit so that the deviation D approaches zero (ultimately, the deviation D becomes zero) (S6 to S8).

[0051] Specifically, the flow control unit 72 determines a flow rate correction amount for the hydraulic fluid that corresponds to the pressure correction amount for a closed circuit such that the deviation D becomes zero. The flow rate correction amount is the correction amount (mL / s) for the flow rate of the hydraulic fluid that flows per second. The relationship between the pressure correction amount and the flow rate correction amount is determined in advance according to the expansion and contraction characteristics (elastic properties, spring constant) of the hydraulic cylinder 41.

[0052] The flow control unit 72 then controls the hydraulic pump HP so that the hydraulic fluid flows through the closed circuit with the determined flow correction amount (operates the flow rate of the hydraulic fluid).

[0053] For example, if the bearing capacity S of the hydraulic cylinder 41 is greater than or equal to the reference weight Wref (Yes in S6), the flow control unit 72 controls the hydraulic pump HP to perform a flow rate operation that discharges hydraulic fluid from the hydraulic cylinder 41 (upper end of cylinder tube 411), reducing the flow rate of hydraulic fluid per unit time to the above flow rate correction amount (S7). On the other hand, if the bearing capacity S of the hydraulic cylinder 41 is less than the reference weight Wref (No in S6), the flow control unit 72 controls the hydraulic pump HP to perform a flow rate operation that supplies hydraulic fluid to the hydraulic cylinder 41 (upper end of cylinder tube 411), increasing the flow rate of hydraulic fluid per unit time to the above flow rate correction amount (S8). In either case, by controlling the flow rate of hydraulic fluid discharged by the hydraulic pump HP as described above, the bearing capacity S can be brought closer to the reference weight Wref, and ultimately matched to the reference weight Wref.

[0054] Furthermore, for example, if the water surface is rough and the front end of the hull 2 ​​is not touching the water, the hull 2 ​​does not have the necessary support to hold the deck 3 in place. Therefore, even if the amount of hydraulic fluid supplied to the hydraulic cylinder 41 is increased by controlling the hydraulic pump HP, the supporting force S of the deck 3 by the hydraulic cylinder 41 does not increase immediately. The supporting force S only begins to increase after the hull 2 ​​touches the water (after the hull 2 ​​has gained sufficient support). For this reason, in S8, it is desirable to perform feedback control on the amount of hydraulic fluid flow correction to adjust the amount of flow correction (the amount of hydraulic fluid discharged by the hydraulic pump HP) over time.

[0055] [4. Effects] As described above, in this embodiment, the flow control unit 72 adjusts the flow rate of the hydraulic fluid flowing through the closed circuit (by controlling the hydraulic pump HP) so that the supporting force S of the hydraulic cylinder 41 approaches a preset reference weight Wref which is the weight supported by the hydraulic cylinder 41 (S4~S8).

[0056] As described above, when the hull 2 ​​approaches the deck 3 due to the swell of the water surface and the pressure detected by the pressure detection unit 61 increases, the flow rate control unit 72 controls the hydraulic pump HP so that hydraulic fluid is discharged from the hydraulic cylinder 41 (S7). In this way, the increase in pressure can be absorbed by the discharge of hydraulic fluid from the hydraulic cylinder 41. Conversely, when the pressure detected by the pressure detection unit 61 decreases, the flow rate control unit 72 controls the hydraulic pump HP so that hydraulic fluid is supplied to the hydraulic cylinder 41 (S8). In this way, the decrease in pressure can be compensated for by the supply of hydraulic fluid.

[0057] Therefore, as shown in Figure 10, even when the hull 2 ​​moves up and down due to the swell of the water surface WS, and the hydraulic cylinder 41 is subjected to an external force in the extension and contraction direction, while a specific part of the deck 3 (e.g., the bow) is in contact with the pole PO, the vertical movement of at least the specific part of the deck 3 can be suppressed. As a result, the specific part can be kept at the target height position H0 in the vertical direction. Thus, a friction force sensor that detects the frictional force against the structure in order to minimize the relative motion between the structure and the ship, as in the conventional system, is unnecessary. In other words, the vertical movement of the bow of the deck 3 accompanying the vertical movement of the hull 2 ​​can be suppressed without the need for a friction force sensor. Furthermore, since a friction force sensor is unnecessary, there is no need for a pressing force to press the deck 3 against the pole PO in order to generate a frictional force between the deck 3 and the pole PO. In other words, according to the control of this embodiment, a specific part of the deck 3 (bow) can be fixed to the pole PO without relying on the pressing force.

[0058] Furthermore, since a friction force sensor is not required, the control described in this embodiment can be performed even without bringing the deck 3 into contact with the pole PO. Therefore, for example, as shown in Figure 11, the control of this embodiment can be applied even during the approach phase (while sailing) when the multi-hull vessel 1 is brought closer to the pole PO. As a result, it becomes easier to bring the deck 3 of the multi-hull vessel 1 into contact with the pole PO at the target height position H0.

[0059] Here, for example, increases or decreases in weight due to increases or decreases in materials loaded onto the multi-hull vessel 1, or onboarding or disembarking of crew members, are within the range of the deadweight capacity. Deadweight capacity is the tonnage (weight) obtained by subtracting the weight of the vessel itself from the total weight when cargo is loaded up to the limit of the full load waterline. Increases or decreases in weight within the deadweight capacity are within a range that can be anticipated in advance, and it is desirable to allow them as an error (dead zone). In this regard, it is desirable that the flow control unit 72 controls the hydraulic pump HP so that the supporting force S approaches the reference weight Wref when the deviation D between the supporting force S of the hydraulic cylinder 41 and the reference weight Wref is greater than or equal to the threshold Dth (S5~S8).

[0060] Furthermore, even if an external force in the expansion and contraction direction is applied to the hydraulic cylinder 41 due to the vertical movement of the hull 2 ​​caused by the swell of the water surface WS, it is desirable for the flow control unit 72 to perform the following control in order to cancel the effect of that external force and reliably suppress the vertical movement of at least a specific part of the deck (for example, the bow section). That is, if the support force S is greater than or equal to the standard weight Wref, the flow control unit 72 controls the hydraulic pump HP to discharge hydraulic fluid from the hydraulic cylinder 41, while if the support force S is less than the standard weight Wref, the hydraulic pump HP controls to supply hydraulic fluid to the hydraulic cylinder 41 (S6~S8).

[0061] Furthermore, from the standpoint of facilitating the setting of the standard weight Wref mentioned above, it is desirable that the standard weight Wref be the value obtained by dividing the weight Wd of the deck 3 by the total number n of hydraulic cylinders 41.

[0062] Furthermore, as shown in Figures 10 (especially the center and right-hand figures) and 11, keeping at least the bow of deck 3 at the target height position H0 in the vertical direction, that is, keeping the bow height of deck 3 constant, makes it easier for crew members to board and disembark when the bow of deck 3 is in contact with the structure (e.g., pole PO) between deck 3 and the structure. Also, keeping the bow height of deck 3 constant makes it easier to bring the bow of deck 3 into contact with the structure at the target height position H0 when approaching the structure. Moreover, keeping the bow height of deck 3 constant makes it possible to align the bow of deck 3 with the target height position H0 while slightly lowering the stern (below the target height position H0), thereby making navigation smoother. From this perspective, in a configuration in which multiple hydraulic cylinders 41 include front hydraulic cylinders 41F connected to the front of multiple hulls 2 (see Figure 7), and a hydraulic pump HP includes a front hydraulic pump HP1 connected to the front hydraulic cylinders 41F to form a closed circuit (see Figure 7), it is desirable for the flow control unit 72 to perform the following control. That is, the flow control unit 72 controls the front hydraulic pump HP1 so that the support force SF of at least the front hydraulic cylinders 41F approaches the reference weight Wref (S3~S8).

[0063] Furthermore, when there is a swell on the water surface WS and the hull 2 ​​moves up and down, it is desirable to keep the deck 3 horizontal or as close to horizontal as possible in order to make it easier for crew members to board and disembark when the deck 3 is in contact with the structure, and to make it easier to bring the bow of the deck 3 into contact with the structure at the target height position H0 when the deck 3 is brought closer to the structure. To achieve this, it is desirable to control the flow rate of the aft hydraulic pump HP2 in the same way as the forward hydraulic pump HP1. In other words, in a configuration in which multiple hydraulic cylinders 41 include a rear hydraulic cylinder 41R connected to the rear of multiple hulls 2 (see Figure 7), and a hydraulic pump HP includes a rear hydraulic pump HP2 connected to the rear hydraulic cylinder 41R to form a closed circuit (see Figure 7), it is desirable for the flow control unit 72 to control the rear hydraulic pump HP2 so that the support force SR of the rear hydraulic cylinder 41R approaches the reference weight Wref (S3~S8).

[0064] Furthermore, from the viewpoint of reliably and easily determining the support force S that each hydraulic cylinder 41 provides to the deck 3, it is desirable that the support force calculation unit 71 calculates the support force S using the above-mentioned equation (3) (S3). In other words, it is desirable that the support force calculation unit 71 calculates the support force S based on the pressure detected by the pressure detection unit 61 and the cylinder area of ​​the hydraulic cylinder 41.

[0065] [5. Setting the target height position] By the way, the target height position H0 mentioned above can be determined as follows. Figure 12 is a schematic diagram illustrating the positional relationship between the target height position H0 with respect to the reference height position Href, the hull 2, and the deck 3. First, the flow control unit 72 determines the reference height position Href, which is the center of the fluctuation in the vertical movement of the hull 2 ​​due to the swell of the water surface.

[0066] Here, the height of the hull 2 ​​fluctuates periodically due to the swell of the water surface, but it can be estimated by subtracting the vertical length of the hydraulic cylinder 41 from the height of the deck 3 detected by the height detection device 80. The vertical length of the hydraulic cylinder 41 can be calculated based on the stroke length in the extension and retraction direction of the hydraulic cylinder 41 detected by monitoring, and the inclination angle of the hydraulic cylinder 41 relative to the hull 2 ​​(or deck 3).

[0067] Therefore, the flow control unit 72 can determine the minimum (lowest position) and maximum (highest position) of the height of the hull 2, which fluctuates periodically in the vertical direction, based on the height position of the deck 3 and the vertical length of the hydraulic cylinder 41. The flow control unit 72 recognizes the average of the minimum and maximum values ​​as the center of the vibration amplitude of the hull 2, and determines this center position as the reference height position Href.

[0068] Once the reference height position Href is determined, the flow rate control unit 72 determines the position obtained by adding a predetermined value Hd to the reference height position Href as the target height position H0.

[0069] In this embodiment, the bow-holding control is performed using a generally readily available device such as an IMU as the height position detection device 80. That is, in determining the target height position H0, it is desirable that the flow control unit 72 performs the following control without using a special sensor capable of detecting the absolute height from sea level 0m. Specifically, the flow control unit 72 estimates the height position of the hull 2 ​​based on the height position of the deck 3 detected by the height detection device 80 and the length of the hydraulic cylinder 41, and recognizes the vertical fluctuation center (reference height position Href) when the height position of the hull 2 ​​fluctuates periodically in the vertical direction. The flow control unit 72 determines the target height position H0 by adding a predetermined value Hd to the fluctuation center. Then, as described above, the flow control unit 72 controls the hydraulic pump HP to adjust the flow rate of the hydraulic fluid flowing through the closed circuit so that the bow of the deck 3 approaches the target height position H0.

[0070] Furthermore, in response to vertical fluctuations of the hull 2 ​​due to swells on the water surface, when bringing the bow of the deck 3 closer to the target height position H0, it is desirable that the above predetermined value Hd be a value corresponding to the center of the extension and retraction stroke of the hydraulic cylinder 41, from the following perspective. Here, the above perspective is to ensure a similar maximum adjustment range in both the direction of contracting or extending the hydraulic cylinder 41 relative to the target height position H0, and to extend or retract the hydraulic cylinder 41 within the range of that maximum adjustment range to bring the bow of the deck 3 closer to the target height position H0.

[0071] Furthermore, the position control to bring the bow of deck 3 closer to the target height position H0 may be performed in conjunction with the force control described above, which adjusts the support force S of the hydraulic cylinder 41, or it may be performed independently. When the flow control unit 72 performs both position control and force control together, the flow rate correction value of the hydraulic fluid required for position control and the flow rate correction value of the hydraulic fluid required for force control are added together.

[0072] Incidentally, if the height position of deck 3 is within the extension / retraction stroke range of the hydraulic cylinder 41 relative to the target height position H0, it is possible to bring deck 3 closer to horizontal by extending or retracting each hydraulic cylinder 41. Therefore, in this case, the extension / retraction of each hydraulic cylinder 41 may simultaneously maintain the bow height position of deck 3 and the horizontal posture of deck 3. In other words, when the height position of deck 3 detected by the height detection device 80 is within the extension / retraction stroke range of the hydraulic cylinder 41 relative to the target height position H0, the flow control unit 72 may control the hydraulic pump HP so that the bow of deck 3 approaches the target height position H0 and deck 3 approaches a horizontal posture.

[0073] On the other hand, if the height of deck 3 exceeds the range of extension and retraction stroke of the hydraulic cylinder 41 relative to the target height position H0, it is difficult to bring deck 3 closer to horizontal by extension and retraction of each hydraulic cylinder 41 alone. Therefore, in this case, it is desirable to control the hydraulic pump HP so that the bow of deck 3 approaches the target height position H0, thereby maintaining at least the bow height of deck 3. In other words, when the height of deck 3 exceeds the range of extension and retraction stroke of the hydraulic cylinder 41 relative to the target height position H0, the flow control unit 72 may control the hydraulic pump HP so that the bow of deck 3 approaches the target height position H0.

[0074] [6. Other] As in this embodiment, a multi-hulled vessel 1 in which the deck 3 is located above the left and right hulls 2 and the main hull 5 is also called a trimaran. In the trimaran structure, a large deck 3 can be secured, so a large amount of equipment and parts necessary for work can be loaded onto the deck 3 and transported to the destination. In addition, as described above, workers can board the main hull 5 below the deck 3. Therefore, trimarans are very useful in that they can efficiently transport workers and equipment.

[0075] However, the trimaran 1 in this embodiment is not limited to trimarans, but may be other trimarans such as catamarans. For example, a catamaran is constructed by omitting the main hull 5 from the trimaran 1 shown in Figure 1, etc. Even if the trimaran 1 is a catamaran, it is possible to control the bow position and position of the deck by controlling the hydraulic pump HP in the same way as in this embodiment, thereby obtaining the same effects as in this embodiment.

[0076] The bow-holding control described in this embodiment is, of course, applicable to vessels having only one hull 2. In other words, the bow-holding control of this embodiment can also be applied to vessels in which the deck 3 is located above a single hull 2 ​​and the support mechanism 4 supports the deck 3 relative to the hull 2.

[0077] [7. Addendum] The vessel described in this embodiment can also be described as the vessel shown in the following appendix.

[0078] The vessels mentioned in Appendix (1) are Haru and, Hydraulic cylinder and The hull and the deck connected via the hydraulic cylinder, A hydraulic pump connected to the aforementioned hydraulic cylinder to form a closed circuit, A support force calculation unit calculates the support force that the hydraulic cylinder provides to support the deck, The system includes a flow control unit that controls the hydraulic pump based on the aforementioned support force to adjust the flow rate of the hydraulic fluid flowing through the (closed) circuit, The flow rate control unit adjusts the flow rate so that the supporting force of the hydraulic cylinder approaches a preset reference weight which is the weight supported by the hydraulic cylinder.

[0079] The vessels in Appendix (2) are, in the vessels described in Appendix (1), The flow rate control unit controls the hydraulic pump so that the supporting force approaches the reference weight when the deviation (absolute value) between the supporting force of the hydraulic cylinder and the reference weight is greater than or equal to a threshold.

[0080] The vessels in Appendix (3) are, in the vessels described in Appendix (2), The flow rate control unit controls the hydraulic pump to discharge the hydraulic fluid from the hydraulic cylinder when the supporting force is equal to or greater than the standard weight, while controlling the hydraulic pump to supply the hydraulic fluid to the hydraulic cylinder when the supporting force is less than the standard weight.

[0081] The vessels in Appendix (4) are, in any of the vessels described in Appendix (1) to (3), The facility comprises multiple hydraulic cylinders, The aforementioned standard weight is the weight of the deck divided by the total number of hydraulic cylinders.

[0082] The vessels in Appendix (5) are, in the vessels described in Appendix (4), The hull comprises multiple such hulls, The plurality of hydraulic cylinders include front hydraulic cylinders connected to the front of the plurality of hulls, The hydraulic pump includes a front hydraulic pump that is connected to the front hydraulic cylinder to form a closed circuit. The flow control unit controls the front hydraulic pump such that the support force of the front hydraulic cylinder approaches the reference weight.

[0083] The vessels in Appendix (6) are, in the vessels described in Appendix (5), The plurality of hydraulic cylinders include rear hydraulic cylinders connected to the rear of the plurality of hulls, The hydraulic pump includes a rear hydraulic pump that is connected to the rear hydraulic cylinder to form a closed circuit. The flow control unit controls the rear hydraulic pump so that the support force of the rear hydraulic cylinder approaches the reference weight.

[0084] The vessels referred to in Appendix (7) are, in any of the vessels described in Appendix (1) to (6), The (closed) circuit further includes a pressure detection unit that detects a pressure that changes in accordance with an external force applied to the hydraulic cylinder, The bearing capacity calculation unit calculates the bearing capacity based on the pressure.

[0085] The vessels in Appendix (8) are, in the vessels described in Appendix (7), The bearing force calculation unit calculates the bearing force based on the pressure detected by the pressure detection unit and the cylinder area of ​​the hydraulic cylinder.

[0086] The vessels in Appendix (9) are, in any of the vessels listed in Appendix (1) to (8), The device further includes a height detection device for detecting the height position of the deck, The flow rate control unit estimates the height of the hull based on the height of the deck detected by the height detection device and the length of the hydraulic cylinder, recognizes the center of vertical fluctuation when the height of the hull periodically fluctuates in the vertical direction, determines a target height position by adding a predetermined value to the center of fluctuation, and controls the hydraulic pump to adjust the flow rate of the hydraulic fluid flowing through the (closed) circuit so that the bow of the deck approaches the target height position.

[0087] The vessels in Appendix (10) are, in the vessels described in Appendix (9), The predetermined value is the value corresponding to the midpoint of the extension and retraction stroke of the hydraulic cylinder.

[0088] The vessels in Appendix (11) are, in the vessels described in Appendix (9) or (10), The flow rate control unit controls the hydraulic pump so that the bow of the deck approaches the target height and the deck approaches a horizontal position when the height of the deck detected by the height detection device is within the extension / retraction stroke range of the hydraulic cylinder relative to the target height; on the other hand, when the height of the deck exceeds the extension / retraction stroke range of the hydraulic cylinder relative to the target height, the flow rate control unit controls the hydraulic pump so that the bow of the deck approaches the target height.

[0089] Although embodiments of the present invention have been described above, the scope of the present invention is not limited thereto, and it can be expanded or modified without departing from the spirit of the invention. [Industrial applicability]

[0090] This invention can be used, for example, in multi-hulled vessels such as trimarans and catamarans. [Explanation of Symbols]

[0091] 1. Multihulled ship 2 Haru 3 decks 41 Hydraulic Cylinder 41F Front hydraulic cylinder 41R Rear hydraulic cylinder 61 Pressure detection unit 71 Supporting force calculation section 72 Flow Control Unit 80 Height detection device HP Hydraulic Pump HP1 Front Hydraulic Pump HP2 Rear Hydraulic Pump

Claims

1. Haru and, Hydraulic cylinder and The hull and the deck connected via the hydraulic cylinder, A hydraulic pump connected to the aforementioned hydraulic cylinder to form a closed circuit, A support force calculation unit calculates the support force that the hydraulic cylinder provides to support the deck, The circuit includes a flow control unit that controls the hydraulic pump based on the support force to adjust the flow rate of the hydraulic fluid flowing through the circuit, The flow control unit adjusts the flow rate so that the supporting force of the hydraulic cylinder approaches a preset reference weight which is the weight supported by the hydraulic cylinder. The facility comprises multiple hydraulic cylinders, The standard weight is the weight of the deck divided by the total number of hydraulic cylinders, in this vessel.

2. The vessel according to claim 1, wherein the flow control unit controls the hydraulic pump so that the supporting force approaches the reference weight when the deviation between the supporting force of the hydraulic cylinder and the reference weight is greater than or equal to a threshold.

3. The vessel according to claim 2, wherein the flow rate control unit controls the hydraulic pump to discharge the hydraulic fluid from the hydraulic cylinder when the support force is equal to or greater than the standard weight, and controls the hydraulic pump to supply the hydraulic fluid to the hydraulic cylinder when the support force is less than the standard weight.

4. comprising a plurality of the hulls, The plurality of hydraulic cylinders include front hydraulic cylinders connected to the front of the plurality of hulls, The hydraulic pump includes a front hydraulic pump that is connected to the front hydraulic cylinder to form a closed circuit. The vessel according to claim 1, wherein the flow control unit controls the front hydraulic pump such that the support force of the front hydraulic cylinder approaches the reference weight.

5. The plurality of hydraulic cylinders include rear hydraulic cylinders connected to the rear of the plurality of hulls, The hydraulic pump includes a rear hydraulic pump that is connected to the rear hydraulic cylinder to form a closed circuit. The vessel according to claim 4, wherein the flow control unit controls the rear hydraulic pump so that the support force of the rear hydraulic cylinder approaches the reference weight.

6. The circuit further comprises a pressure detection unit provided therein, which detects a pressure that changes in accordance with an external force applied to the hydraulic cylinder, The ship according to any one of claims 1 to 5, wherein the bearing capacity calculation unit calculates the bearing capacity based on the pressure.

7. The ship according to claim 6, wherein the bearing force calculation unit calculates the bearing force based on the pressure detected by the pressure detection unit and the cylinder area of ​​the hydraulic cylinder.

8. Further comprising a height detection device for detecting the height position of the deck, The vessel according to claim 1, wherein the flow rate control unit estimates the height of the hull based on the height of the deck detected by the height detection device and the length of the hydraulic cylinder, recognizes the center of vertical fluctuation when the height of the hull periodically fluctuates in the vertical direction, determines a position obtained by adding a predetermined value to the center of fluctuation as the target height, and controls the hydraulic pump to adjust the flow rate of the hydraulic fluid flowing through the circuit so that the bow of the deck approaches the target height.

9. The vessel according to claim 8, wherein the predetermined value is a value corresponding to the center of the extension and retraction stroke of the hydraulic cylinder.

10. The vessel according to claim 8 or 9, wherein the flow rate control unit controls the hydraulic pump so that the bow of the deck approaches the target height position and the deck approaches a horizontal position when the height position of the deck detected by the height detection device is within the range of the extension and retraction stroke of the hydraulic cylinder with respect to the target height position, and controls the hydraulic pump so that the bow of the deck approaches the target height position when the height position of the deck exceeds the range of the extension and retraction stroke of the hydraulic cylinder with respect to the target height position.

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