watercraft

Abstract

To provide a ship capable of promoting idling of a rotary blade on the downstream side.SOLUTION: The vessel 1 includes a rotary wing 60A and a rotary wing 60B. Here, the rotary blade 60A is disposed on the upstream side of the rotary blade 60B with respect to the water flow WF. Therefore, the rotary wing 60A and the water flow WF flowing to the rotary wing 60B are affected by the rotary wing 60A and then flow to the rotary wing 60B as a wake RF. The rotary wing 60B does not receive a mechanical rotational force for a predetermined purpose (regeneration or the like), and performs idling in which the rotary wing is rotated by the force of the water flow WF. On the other hand, the structure of the rotary blade 60B on the upstream side can be adjusted to promote idling of the rotary blade 60A on the downstream side. That is, the structure of the rotary wing 60A on the upstream side can be adjusted so that the water flow passing through the rotary wing 60A becomes a flow that promotes the idling of the rotary wing 60B on the downstream side. As described above, it is possible to promote the idling of the rotary blade 60B on the downstream side.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present invention relates to a ship. [Background technology]

[0002] In recent years, ships that generate thrust using renewable energy such as wind power have become known in order to reduce GHG gases such as CO2. For example, the ship described in Patent Document 1 is equipped with a wind propulsion unit on the hull that propels the hull using wind power, in addition to a propeller-based thruster. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-45018 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, in strong winds, the above-mentioned ships generate electricity using an electric motor by rotating a single large propeller. In light winds, the propeller is rotated using stored electricity to generate thrust. However, conventional ships use a single large propeller, which increases fluid resistance and causes problems such as a decrease in ship speed when sailing. To solve this problem, upstream and downstream propellers are sometimes installed, and the downstream propeller is allowed to rotate freely during regeneration. In this case, promoting the free rotation of the downstream propeller can improve regeneration efficiency. Thus, there has been a demand for promoting the free rotation of the downstream rotor.

[0005] The present invention has been made to solve the above problems, and has an object to provide a ship that can promote free rotation of the downstream rotor. [Means for solving the problem]

[0006] The vessel comprises a hull according to the present invention, a first rotor, and a second rotor, the first rotor being positioned upstream of the second rotor with respect to the water flow, and the structure of the first rotor being adjustable to promote free rotation of the second rotor.

[0007] The vessel according to the present invention includes a first rotor and a second rotor. Here, the first rotor is disposed upstream of the second rotor with respect to the water flow. Therefore, the water flowing toward the first rotor and the second rotor flows to the second rotor after being influenced by the first rotor. For a predetermined purpose, the second rotor rotates freely by the force of the water flow without receiving any mechanical rotational force. In contrast, the structure of the first rotor can be adjusted to promote the free rotation of the second rotor. That is, the structure of the first rotor can be adjusted so that the water flow passing through the first rotor is a flow that promotes the free rotation of the second rotor. As a result, the free rotation of the downstream rotor can be promoted.

[0008] In the ship, the second rotor may perform regeneration by rotating freely. In this case, the first rotor promotes the rotation of the second rotor, thereby improving regeneration efficiency.

[0009] The vessel may further include a wind propulsion unit that propels the hull using wind power. In this case, the vessel can sail the hull using the wind propulsion unit. The second rotor can regenerate by rotating freely when sailing. Furthermore, the first rotor can promote the rotation of the second rotor when sailing. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a ship that can promote free rotation of the downstream rotor. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic cross-sectional view showing an example of a ship according to an embodiment of the present invention. [Figure 2](a) is a diagram explaining the principle of the rotor sail, and (b) is a plan view of the ship. [Figure 3] FIG. 2 is a schematic side view of the aft structure of the vessel. [Figure 4] FIG. 1 is a diagram conceptually illustrating the energy efficiency of different propeller arrangements. [Figure 5] FIG. 4 is a block diagram showing control details in a motor-driven mode. [Figure 6] FIG. 10 is a block diagram showing the control contents in sailing mode. [Figure 7] FIG. 2 is a block diagram showing the control contents in motor sailing mode. [Figure 8] 1 is a graph showing the relationship between wind speed, thrust provided by the wind propulsion unit, and power used to rotate the wind propulsion unit. [Figure 9] 10 is a table showing control modes and the operating status of each device in each control mode. [Figure 10] (a) is a conceptual diagram showing the downstream rotor, and (b) is a conceptual diagram showing the upstream rotor. [Figure 11] 10A is a table showing the rotor settings in each operation mode, and FIG. 10B is a table showing the rotor settings in the free rotation mode. [Figure 12] FIG. 10 is a diagram showing the setting contents of the rotor blades in setting 1. [Figure 13] FIG. 10 is a diagram showing the setting contents of the rotor blades in setting 2. [Figure 14] FIG. 10 is a diagram showing the setting contents of the rotor blades in setting 3. [Figure 15] FIG. 10 is a diagram showing the setting contents of the rotor blades in setting 3. [Figure 16] FIG. 10 is a diagram showing the setting contents of the rotor blades in setting 4. [Figure 17] 10(a) is a diagram showing the arrangement of rotors according to a modified example, and FIG. 10(b) is a table showing the settings of rotors in each operation mode. [Figure 18] 10 is a table showing the settings of the rotor blades in the free rotation mode. DETAILED DESCRIPTION OF THE INVENTION

[0012] A preferred embodiment of the present invention will be described below with reference to the drawings. In the following description, the terms "forward" and "aft" refer to the direction of travel of the hull, the term "lateral" refers to the left-right (width) direction of the hull, and the terms "upper" and "lower" refer to the up-down direction of the hull.

[0013] 1 is a schematic cross-sectional view showing an example of a ship according to an embodiment of the present invention. The ship 1 is a ship that transports petroleum-based liquid cargo such as crude oil or liquid gas, and is, for example, an oil tanker. Note that the ship is not limited to an oil tanker, and may be, for example, a bulk carrier or various other types of ships.

[0014] As shown in Figure 1, the ship 1 comprises a hull 11, a propeller 12, and a plurality of wind-propulsion units 10. The hull 11 has a bow section 2, a stern section 3, an engine room 4, a pump room 5, and a cargo room 6. An upper deck 19 is provided above (or inside) the hull 11. The bow section 2 is located on the front side of the hull 11. The stern section 3 is located on the rear side of the hull 11.

[0015] The bow 2 has a shape designed to reduce wave-making resistance, for example, when the ship is at full load. The propeller 12 mechanically generates thrust for the hull 11, and is, for example, a propeller shaft. The propeller 12 is installed below the waterline (the water surface of the sea W) at the stern 3 during propulsion. Also, an azimuth propeller 15, which also functions as a rudder for adjusting the propulsion direction, is installed below the waterline at the stern 3. In the example shown in FIG. 1, the ship 1 is equipped with multiple propellers 12A, 12B. The multiple propellers 12A, 12B are arranged facing each other in the fore-and-aft direction.

[0016] The engine room 4 is located adjacent to the bow side of the stern section 3. The engine room 4 is a compartment for accommodating the main engine 16 that provides driving force to the propeller 12 (the front propeller 12A). An accommodation area 22 and an exhaust chimney 23 are provided above the engine room 4 on the upper deck 19. The pump room 5 is located adjacent to the bow side of the engine room 4. The pump room 5 is a compartment where pumps 17 and other components are located. The cargo hold 6 is located between the bow section 2 and the pump room 5. The cargo hold 6 is a compartment for storing petroleum-based cargo. The cargo hold 6 is divided into multiple cargo oil tanks 26 and multiple ballast tanks 27 by using a double-hull structure consisting of an outer plating 20 and an inner bottom plating 21. The cargo oil tank 26 holds petroleum-based cargo to be transported by the ship 1. The ballast tank 27 stores ballast water in an amount appropriate to the size of the ship.

[0017] The wind propulsion unit 10 is a mechanism that propels the hull 11 using wind power. In this embodiment, a rotor-type wind propulsion mechanism is used as the wind propulsion unit 10. Multiple wind propulsion units 10 (four in this example) are provided on the upper deck 19 of the hull 11, aligned in the fore-and-aft direction. As shown in FIG. 2(a), the wind propulsion unit 10 includes a cylindrical rotor sail 31 extending vertically and an electric motor 32 that rotates the rotor sail 31. When wind WD blows into the rotor sail 31 from the side, the rotation direction of the rotor sail 31 and the wind WD are opposite to each other at the rear, but are aligned with the wind WD at the front. This creates a pressure difference between the front and rear of the rotor sail 31, generating a forward thrust force PF (the Magnus effect). As shown in FIG. 2(b), when wind WD blows from the side of the hull 11, the thrust force PF of each wind propulsion unit 10 propels the hull 11 forward. 1, the rotor sail 31, which is the wind propulsion unit 10, may be provided on the wall of the cargo hold 6. In this way, even when supporting a heavy structure such as the rotor sail 31, providing it on the wall of the cargo hold 6 can serve as a reinforcing member for supporting the rotor sail.

[0018] The structure of the stern side of the vessel 1 will be described in detail with reference to Figure 3. Figure 3 is a schematic side view of the structure of the stern side of the vessel 1. The multiple propellers 12 of the vessel 1 are configured with contra-rotating propellers 35. The front propeller 12A has a front propeller 33 attached to the hull 11 and driven by the main engine 16. The propeller 12A is connected to the main engine 16 in the engine room 4 via a shaft 34 extending forward from its front end. An electric motor 36 that recovers electric power from the rotational force of the shaft 34 is provided midway along the shaft 34. The rear propeller 12B is rotatably attached outside the hull 11, positioned opposite the front propeller 33, and has a rear propeller 37 driven by an electric motor 38. The rear propeller 37 is attached to an azimuth propeller 15 that also functions as a rudder. The rear propeller 12B is an azimuth propeller with a rear propeller 37 attached to a pod that can rotate 360 ​​degrees horizontally. The contra-rotating propeller 35 has the front and rear propellers 33 and 37 rotating in opposite directions, and the energy of the rotational flow of the front propeller 33 is recovered by the rear propeller 37 and rectified into an axial flow, eliminating energy loss due to the rotational flow and leaving only the axial flow at the rear, improving energy efficiency. A diesel generator 39 is installed in the engine room 4. A battery 40 is installed, for example, in the stern 3.

[0019] FIG. 4 is a conceptual diagram illustrating the energy efficiency of various propeller arrangements. As shown in FIG. 4(a), the propulsion energy of a ship equipped with a propeller 12 having a single large propeller is used as the base. FIGS. 4(b), 4(c), and 4(d) are configured to obtain the same thrust as that of FIG. 4(a). In this case, the propulsion energy of a ship equipped with two propellers 12 having small propellers arranged in parallel, as shown in FIG. 4(c), is 5% higher than that of FIG. 4(a). The propulsion energy of a ship equipped with three propellers 12 having small propellers arranged in parallel, as shown in FIG. 4(d), is 10% higher than that of FIG. 4(a). On the other hand, the propulsion energy of a ship equipped with a contra-rotating propeller 35, as shown in FIG. 4(b), can be reduced by approximately 10 to 15% compared to that of FIG. 4(a).

[0020] 5 to 7, the control system 100 of the vessel 1 will be described. The control system 100 controls the wind propulsion unit 10 and the propellers 12A and 12B according to the available wind conditions. When the hull 11 is moving by the wind propulsion unit 10, the control system 100 uses the propeller 12 for regeneration. In this embodiment, of the multiple propellers 12A and 12B, the control system 100 uses the rear propeller 12B for regeneration and stops the front propeller 12A. As shown in FIG. 5, the control system 100 includes the wind propulsion unit 10 (rotor sail 31, electric motor 32), the front propeller 12A (main engine 16, electric motor 36, front propeller 33, shaft 34), the rear propeller 12B (electric motor 38, rear propeller 37), a generator 39, and a battery 40. The control system 100 also includes a management system 50 that manages the energy of the above-mentioned devices. The management system 50 is a system that exchanges and distributes current within the control system 100. In Figures 5 to 7, among the lines connecting the management system 50 and each device, solid lines indicate output current, dashed lines indicate regenerative current, and dashed lines indicate current cutoff.

[0021] Here, the control system 100 can switch control modes depending on the wind speed. The control system 100 can switch control modes to achieve the optimal overall control mode, taking into account the relationship between the wind speed and the thrust and required power obtained by the wind propulsion unit 10. The control system 100 has a "motor propulsion mode" in which the vessel is propelled only by the propeller 12 without using the wind propulsion unit 10, a "motor sailing mode" in which the vessel is propelled using both the wind propulsion unit 10 and the propeller 12, and a "sailing mode" in which the vessel is propelled only by the wind propulsion unit 10 without using the propeller 12.

[0022] FIG. 8 is a graph showing the relationship between wind speed, thrust generated by the wind propulsion unit 10, and power used to rotate the wind propulsion unit 10. As shown in FIG. 9, in the wind speed range of 0 to 5 m / s, the thrust generated by the wind propulsion unit 10 is small. Therefore, in this range, the control system 100 is set to motor propulsion mode. In the wind speed range of 5 to 10 m / s, a reasonable amount of thrust can be generated, but the thrust generated by the wind propulsion unit 10 is insufficient. Therefore, in this range, the control system 100 is set to motor sailing mode. In the wind speed range of 10 to 20 m / s, thrust generated by the wind propulsion unit 10 alone is sufficient for navigation. Therefore, in this range, the control system 100 is set to sailing mode. In the wind speed range of 20 m / s or higher, problems occur due to excessive wind strength, so the control system 100 is set to motor propulsion mode. FIG. 9 is a table showing the control modes and the operating status of each device in each control mode.

[0023] FIG. 5 is a block diagram showing the control content in the propulsion mode. The wind speed in FIG. 5 is 0 (m / s). Although specific values ​​of the power output by each device are shown in FIGS. 5 to 7, these are merely examples for the purpose of explanation and can be changed as appropriate. For ease of understanding, the explanation will be given without taking into account energy loss, etc. As shown in FIG. 5, the control system 100 operates the main engine 16. At this time, the output of the main engine 16 is "3200 kW." The electric motor 36 recovers a portion of the output of the main engine 16 (1800 kW) as regenerative current. As a result, the front propulsion unit 12A generates thrust with an output of "1800 kW."

[0024] The management system 50 supplies the 1400 kW of power regenerated by the electric motor 36 to the electric motor 38 of the rear propeller 12B. This causes the electric motor 38 to rotate the rear propeller 37, and the rear propeller 12B generates thrust with an output of 1400 kW. As a result, the propellers 12A and 12B generate thrust with a total output of 3200 kW. Meanwhile, the control system 100 has stopped the wind power propulsion unit 10. Therefore, the thrust from the wind power propulsion unit 10 is 0 kW.

[0025] Figure 6 is a block diagram showing the control procedures in sailing mode. The wind speed in Figure 6 is greater than 15 (m / s) and less than 20 (m / s). As shown in Figure 6, the control system 100 stops the main engine 16. This stops the front propeller 12A, and the power regenerated by the electric motor 36 also becomes "0 kW." The management system 50 supplies "4 x 100 kW" of power to the electric motors 32 of the four wind propulsion units 10. As a result, the wind propulsion units 10 generate thrust greater than "4000 kW."

[0026] At this time, the control system 100 allows the rear propeller 37 of the rear propeller 12B to rotate freely. As a result, the rear propeller 37 rotates freely as the hull 11 sails. The electric motor 38 recovers 400 kW of power generated by the rotation of the rear propeller 37 as regenerative power. The electric motor 38 outputs the 400 kW of power regenerated by the rear propeller 12B to the management system 50. The management system 50 supplies 4 x 100 kW of regenerated power to the electric motors 32 of the four wind propulsion units 10. This allows the wind propulsion units 10 to operate using the power regenerated by the rear propeller 12B. Note that the management system 50 stores any surplus regenerated power in the battery 40.

[0027] FIG. 7 is a block diagram showing the control details for the motor sailing mode. The wind speed in FIG. 7 is 5 (m / s). As shown in FIG. 7, the control system 100 operates the main engine 16. At this time, the output of the main engine 16 is 2680 kW. The electric motor 36 recovers a portion of the output of the main engine 16 (1330 kW) as regenerative current. As a result, the front propeller 12A generates thrust with an output of 1350 kW.

[0028] The management system 50 supplies "1050 kW", which is a portion of the "1330 kW" of power regenerated by the electric motor 36, to the electric motor 38 of the rear propeller 12B. This causes the electric motor 38 to rotate the rear propeller 37, and the rear propeller 12B generates thrust with an output of "1050 kW". As a result, the propellers 12A and 12B generate thrust with a total output of "2400 kW".

[0029] The management system 50 supplies 4 x 70 kW, a portion of the 1,330 kW of power regenerated by the electric motor 36, to each of the electric motors 32 of the four wind propulsion units 10. This causes the wind propulsion units 10 to generate a thrust of 800 kW. As a result, the hull 11 travels using the thrust from both the propellers 12A, 12B and the wind propulsion units 10.

[0030] (Additional information for each mode) Next, an example of transitional control of the operation mode shown in FIG. 9 will be described.

[0031] (1) Transitional control from sail mode to motor sail mode involves switching the main engine 16 from OFF to ON. This also switches the front propeller 33 from OFF to propulsion mode. The rear propeller 37 also switches from regeneration mode to propulsion mode, making it possible to maintain the thrust of the boat 1 when switching from sailing to motor sailing.

[0032] (2) Next, to switch from motor-powered mode to motor-sailed mode, the rotor sail 31 is switched from Off to On to gradually prepare for sailing.

[0033] (3) To switch from motor sail mode to sail mode, simply turn off the main engine 16. However, it is preferable to switch to sail mode when the wind speed is expected to be 10 m / sec or higher for a predetermined period of time or more. If the predetermined period of time or more is not expected, the boat must return to motor sail mode and turn the main engine 16 on again, which increases the amount of fuel injected at startup and worsens fuel consumption.

[0034] (4) Similarly, to switch from sail mode to motor sail mode, the main engine 16 can be turned on, but it is preferable to switch to motor sail mode when the wind speed is expected to be below 10 m / sec for a predetermined period of time or longer. This, like (3), also helps prevent the increase in fuel consumption caused by repeatedly starting and stopping the main engine 16.

[0035] Here, when the rear propeller 12B, that is, the propeller 12B downstream with respect to the water flow, performs regeneration, the rear propeller 37 rotates freely. To improve regeneration efficiency, it is preferable to promote the rotation of the rear propeller 37 to increase the rotation speed, increase the torque, or both. Therefore, it is preferable that the structure of the front propeller 33 of the propeller 12A upstream with respect to the water flow be adjustable so as to promote the rotation of the rear propeller 37.

[0036] 10 to 16, an upstream rotor 60A (first rotor) whose structure is adjustable to promote free rotation of a downstream rotor 60B (second rotor) will be described. As shown in FIG. 10(a), the downstream rotor 60B has a main body 61B disposed at the center of rotation and multiple blades 62B extending radially outward from the main body 61B. The downstream rotor 60B may be adjustable in the blade angle, number, axial and rotational positions, and rotation speed of the blades 62B depending on the operating conditions. As shown in FIG. 10(b), the upstream rotor 60A has a main body 61A disposed at the center of rotation and multiple blades 62A extending radially outward from the main body 61A. The upstream rotor 60A may be adjustable in the blade angle, number, axial and rotational positions, and rotation speed of the blades 62A depending on the operating conditions. Although it is preferable that the blade portions 62A, 62B of the rotors 60A, 60B have a variable pitch, they may also have a fixed pitch.

[0037] Referring to FIG. 10(a), the blade angle of the blade portion 62B of the downstream rotor 60B will be described. FIG. 10(a) shows a cross section of one blade portion 62B at the 70% radius position when the blade portion 62B is arranged directly to the side. The 70% radius position is the 70% position in the radial direction when the center of rotation is 0% and the outermost periphery is 100%. When a reference line SL1 extending upward is set and a reference line SL2 of the blade portion 62B is set, the angle of the reference line SL2 in the clockwise direction on the page relative to the reference line SL1 is the blade angle β of the blade portion 62B. Note that the blade portion 62B curves so that the main surface on the opposite side of the reference line SL1 bulges out relative to the reference line SL2. When the wing angle β is between 0 and 90°, it is called "wing angle I", when it is between 90 and 180° it is called "wing angle II", when it is between 180 and 270° it is called "wing angle III", and when it is between 270 and 360° it is called "wing angle IV".

[0038] The blade angle of the blade portion 62A of the upstream rotor 60A will be described with reference to FIG. 10(b). FIG. 10(b) shows a cross section at the 70% radius position of one blade portion 62A arranged directly beside it. When a reference line SL3 extending downward is set and a reference line SL4 of the blade portion 62A is set, the angle of the reference line SL4 measured counterclockwise from the reference line SL3 is the blade angle α of the blade portion 62A. Note that the blade portion 62A curves so that the main surface on the opposite side of the reference line SL3 bulges outward from the reference line SL4. A blade angle α between 0 and 90° is defined as "blade angle A," a blade angle between 90 and 180° is defined as "blade angle B," a blade angle between 180 and 270° is defined as "blade angle C," and a blade angle between 270 and 360° is defined as "blade angle D."

[0039] When adjusting the blade angle of the rotors 60A, 60B, the angle of each of the blades 62A, 62B is changed at the root portion of the blades 62A, 62B relative to the main bodies 61A, 61B. In the following explanation, when describing the rotation direction of the rotors 60A, 60B, the terms "counterclockwise" and "clockwise" are used based on the view from the downstream side to the upstream side of the water flow.

[0040] FIG. 11(a) is a table showing the settings of the rotors 60A, 60B in each operation mode. The operation modes include a "propulsion mode" in which the vessel 1 propels, and a "free-spin mode" in which the downstream rotor 60B rotates freely. As shown in FIG. 11(a), in the propulsion mode, both rotors 60A, 60B rotate at settings suitable for propulsion. In the free-spin mode, the downstream rotor 60B rotates freely at settings suitable for propulsion, or is adjusted to a setting suitable for free spinning and rotates freely. The upstream rotor 60A is adjusted to a position, angle, and rotation (including stopping) that promotes the free spin of the downstream rotor 60B.

[0041] FIG. 11(b) is a table showing the settings of rotors 60A, 60B in free rotation mode. As shown in FIG. 11(b), four settings, "Setting 1" to "Setting 4," are shown here. Note that FIG. 11(b) shows the case where rotor 60A on the upstream side rotates clockwise, so in the case of counterclockwise rotation, simply swap "left" and "right" in the table. Hereinafter, the settings of rotors 60A, 60B in each setting will be described with reference to FIGS. 12 to 16.

[0042] Fig. 12 is a diagram showing the setting contents of rotors 60A, 60B in setting 1. The upper diagram in Fig. 12(a) shows a model of rotors 60A, 60B as viewed from the side, and the lower diagram in Fig. 12(a) shows the positional relationship of the cross sections of blade portions 62A, 62B. The same applies to the other diagrams in Figs. 12 to 16.

[0043] As shown in Figure 12(a), in setting 1, the downstream rotor 60B has a blade angle I, and the upstream rotor 60A is feathered and stopped. Feathering means setting the blade angle α to 90° or 270°. The blade portion 62A of the upstream rotor 60A is stopped at a blade angle that provides minimum resistance. Therefore, the water flow WF becomes a relatively fast wake RF and flows toward the downstream rotor 60B. The free rotation direction D of the downstream rotor 60B is counterclockwise, and is set to a blade angle I. Therefore, the blade portion 62B is subjected to the fast-flowing wake RF, which promotes free rotation in the free rotation direction D.

[0044] As shown in Figure 12(b), in setting 1, the downstream rotor 60B is set to a blade angle III, and the upstream rotor 60A is feathered and stopped. As in Figure 12(a), the blade portion 62B is subjected to a fast wake RF, which promotes free rotation in the free rotation direction D.

[0045] As shown in Figure 13(a), in setting 2, the downstream rotor 60B is set to a blade angle I, and the upstream rotor 60A is stopped or rotates freely at a blade angle A. The blade portion 62A of the upstream rotor 60A is stopped (or rotates freely) at a blade angle that generates a wake RF that induces the downstream rotor 60B to rotate freely in a counterclockwise direction. The blade portion 62B of the downstream rotor 60B is set to a blade angle I that matches the wake RF, so that the blade portion 62B receives the wake RF and promotes free rotation in the rotation direction D.

[0046] 13(b), in setting 2, the downstream rotor 60B is set to blade angle III, and the upstream rotor 60A is stopped or rotates freely at blade angle A. The blade portion 62B of the downstream rotor 60B is set to blade angle III in accordance with the wake RF, so that the blade portion 62B receives the wake RF, promoting free rotation in the free rotation direction D.

[0047] As shown in Figure 14(a), in setting 3, the downstream rotor 60B is set to blade angle II, and the upstream rotor 60A is stopped at blade angle B. The blade portion 62A of the upstream rotor 60A is stopped at a blade angle that generates a wake RF that induces clockwise free rotation of the downstream rotor 60B. The blade portion 62B of the downstream rotor 60B is set to blade angle II that matches the wake RF, so that the blade portion 62B receives the wake RF, promoting free rotation in the free rotation direction D.

[0048] 14(b), in setting 3, the downstream rotor 60B is set to a blade angle IV, and the upstream rotor 60A is stopped at a blade angle B. The blade portion 62B of the downstream rotor 60B is set to a blade angle IV that matches the wake RF, so that the blade portion 62B receives the wake RF, promoting free rotation in the free rotation direction D.

[0049] As shown in Figure 15(a), in setting 3, the downstream rotor 60B is set to blade angle II, and the upstream rotor 60A is stopped at blade angle D. The blade portion 62A of the upstream rotor 60A is stopped at a blade angle that generates a wake RF that induces clockwise free rotation of the downstream rotor 60B. The blade portion 62B of the downstream rotor 60B is set to blade angle II that matches the wake RF, so that the blade portion 62B receives the wake RF and promotes free rotation in the free rotation direction D.

[0050] As shown in Figure 15(b), in setting 3, the downstream rotor 60B has a blade angle IV, and the upstream rotor 60A is stopped at a blade angle D. The blade portion 62B of the downstream rotor 60B is set to a blade angle IV that matches the wake RF, so that the blade portion 62B receives the wake RF and promotes free rotation in the free rotation direction D.

[0051] As shown in Figure 16(a), in setting 4, the downstream rotor 60B is set to blade angle II, and the upstream rotor 60A is rotated clockwise at blade angle A. The blade portion 62A of the upstream rotor 60A is set to blade angle A so as to generate a clockwise wake RF. The blade portion 62B of the downstream rotor 60B is set to blade angle II to match the clockwise wake RF, thereby promoting free rotation in the free rotation direction D as the blade portion 62B receives the wake RF.

[0052] 16(b), in setting 4, the downstream rotor 60B is set to a blade angle IV, and the upstream rotor 60A is rotated clockwise at a blade angle A. The blade portion 62B of the downstream rotor 60B is set to a blade angle IV that matches the clockwise wake RF, so that the blade portion 62B receives the wake RF and promotes free rotation in the free rotation direction D.

[0053] Next, the functions and effects of the boat 1 according to this embodiment will be described.

[0054] The vessel 1 according to this embodiment includes rotors 60A and 60B. Here, rotor 60A is disposed upstream of rotor 60B with respect to the water flow WF. Therefore, the water flow WF flowing toward rotor 60A and rotor 60B is influenced by rotor 60A and then flows to rotor 60B as a wake RF. For a predetermined purpose (such as regeneration), rotor 60B rotates freely by the force of the water flow WF without receiving any mechanical rotational force. In contrast, the structure of the upstream rotor 60A can be adjusted to promote the free rotation of the downstream rotor 60B. That is, the structure of the upstream rotor 60A can be adjusted so that the water flow passing through rotor 60A promotes the free rotation of the downstream rotor 60B. As described above, the free rotation of the downstream rotor 60B can be promoted.

[0055] In the vessel 1, the downstream rotor 60B may perform regeneration by freely rotating. In this case, the upstream rotor 60A promotes the freely rotating of the downstream rotor 60B, thereby improving regeneration efficiency.

[0056] The vessel 1 may further include a wind propulsion unit 10 that propels the hull 11 by wind power. In this case, the vessel 1 can sail the hull 11 using the wind propulsion unit 10. The downstream rotor 60B can perform regeneration by rotating freely when sailing. Furthermore, the upstream rotor 60A can promote the rotation of the downstream rotor 60B when sailing.

[0057] The boat 1 according to this embodiment includes multiple propellers 12 that mechanically generate thrust for the hull 11. The boat 1 also includes a wind propulsion unit 10 that propels the hull 11 using wind power. Therefore, the boat 1 can sail using the wind propulsion unit 10. At this time, the boat 1 can regenerate power using the propellers 12. Furthermore, the boat 1 can sail using mechanical thrust using the propellers 12 when the wind is weak. Here, by using multiple propellers 12, the boat 1 can perform motorized propulsion with improved propulsion efficiency compared to using one large propeller. Furthermore, during regeneration, the boat 1 can reduce the fluid resistance of each propeller 12 by making each propeller 12 smaller, so the boat 1 can perform regeneration with improved regeneration efficiency compared to using one large propeller. As a result, energy efficiency can be improved.

[0058] The vessel 1 may use at least one of the propellers 12B for regeneration and stop the other propellers 12A among the multiple propellers 12. In this case, stopping the propeller 12A that is not used for regeneration can prevent the propeller 12A from acting as a fluid resistance when sailing.

[0059] The multiple propellers 12 may be configured with contra-rotating propellers 35. The contra-rotating propellers 35 allow the downstream propeller 12B to rotate by effectively utilizing the rotational flow of the upstream propeller 12A. Therefore, the propulsion efficiency of the vessel 1 can be improved when propelled by engine power.

[0060] The present invention is not limited to the above-described embodiments.

[0061] In the above embodiment, contra-rotating propellers 35 have been described as an example of multiple propellers, but as long as multiple propellers are used, there are no particular limitations on how they are arranged. For example, both rotors 60A, 60B may be attached to the front shaft, or both may be attached to the rudder-side shaft. Furthermore, as long as the upstream rotor can promote the free rotation of the downstream rotor, there are no particular limitations on the number and arrangement of the rotors.

[0062] For example, as shown in FIG. 17(a), two rotors 160A and 160B may be provided on the upstream side, and one rotor 160C may be provided on the downstream side. FIG. 17(a) is a top view of each rotor 160A, 160B, and 160C. As shown in FIG. 17(a), the rotors 160A and 160B are arranged side by side in the horizontal direction, and the downstream rotor 160C is disposed between the rotors 160A and 160B in the horizontal direction. As shown in FIG. 18(a), the wing portion 162C on the left side of the downstream rotor 160C overlaps with the wing portion 162A on the right side of the upstream rotor 160A. The wing portion 162C on the right side of the downstream rotor 160C overlaps with the wing portion 162B on the left side of the upstream rotor 160B.

[0063] FIG. 17(b) is a table showing the settings of the rotors 160A, 160B, and 160C in each operating mode. As shown in FIG. 17(b), in the propulsion mode, all of the rotors 160A, 160B, and 160C rotate at settings suitable for propulsion. In the free-spinning mode, the downstream rotor 160C either rotates freely at a setting suitable for propulsion or is adjusted to a setting suitable for free spinning. The upstream rotors 160A and 160B are adjusted to a position, angle, and rotation (including stopping) that promotes the free spinning of the downstream rotor 160C.

[0064] Figure 18 is a diagram showing the settings of the rotors 160A, 160B, and 160C in free rotation mode. Figure 18(a) is a model of the rotors 160A, 160B, and 160C viewed from the downstream side of the water flow. Figure 18(b) is a cross-sectional view taken along line XVIIb-XVIIb in Figure 18(a). Figure 18(c) is a cross-sectional view taken along line XVIIc-XVIIc in Figure 18(a).

[0065] As shown in FIG. 18(b), the blade 162A of the upstream rotor 160A on the left side induces a downward wake RF when stationary. The blade 162C of the downstream rotor 160C has a blade angle that matches the wake RF on the left side, and receives the downward wake RF to promote free rotation in the counterclockwise direction D. As shown in FIG. 18(c), the blade 162B of the upstream rotor 160B on the right side induces an upward wake RF when stationary. The blade 162C of the downstream rotor 160C has a blade angle that matches the wake RF on the right side, and receives the upward wake RF to promote free rotation in the counterclockwise direction D. Note that the angle combinations of the blades 162A, 162B, and 162C shown in FIGS. 18(b) and 18(c) are merely examples, and any combination that promotes free rotation can be used. For example, the downstream blade 162C in Figure 18(b) may have blade angle II or blade angle IV, and the upstream blade 162A may have blade angle B or blade angle D. The downstream blade 162C in Figure 18(c) may have blade angle I or blade angle III, and the upstream blade 162B may have blade angle A or blade angle C.

[0066] For example, there are no particular limitations on the number and arrangement of wind propulsion units and how they are provided relative to the hull. The wind propulsion units are not limited to rotor sails and may be any type that can propel the hull using wind power, such as ordinary sails. In addition, the wind propulsion units may be omitted.

[0067] Even when the wind propulsion unit is omitted, the downstream rotor may perform regeneration by receiving the water current of an ocean or river when the vessel is stationary, and the upstream rotor may promote free rotation of the downstream rotor for regeneration.

[0068] The downstream rotor may rotate freely for purposes other than regeneration.

[0069] The structure of the hull 11 is not limited to that shown in FIG. 1, and may be modified as appropriate depending on the intended use. [Explanation of symbols]

[0070] 1...ship, 11...hull, 10...wind propulsion unit, 60A, 160A, 160B...rotor (first rotor), 60B, 160C...rotor (second rotor).

Claims

1. The hull and a first rotor and a second rotor, the first rotor is disposed upstream of the second rotor with respect to the water flow; The marine vessel, wherein a configuration of the first rotor is adjustable to facilitate free rotation of the second rotor.

2. The watercraft according to claim 1 , wherein the second rotor performs regeneration by freely rotating.

3. The watercraft according to claim 1 or 2, further comprising a wind propulsion unit that propels the hull by wind force.

Images