Wind propulsion device

Abstract

A wind propulsion device (1) according to an aspect of the present invention is installed on a movable body (2) and configured to generate propulsive force by receiving wind. The wind propulsion device (1) includes: a rotator (20A, 20B) including a frame (21) having an annular shape around a rotation axis (RC), the rotator (20A, 20B) being rotatable around the rotation axis (RC); and a plurality of blades (10A to 101) each fixed to the frame (21), the plurality of blades (10A to 10I) being provided such that imaginary straight lines connecting respective opposite ends in a direction orthogonal to the rotation axis (RC) are parallel. The plurality of blades (10A to 10I) include a central blade (10A), and an imaginary straight line connecting opposite ends of the central blade (10A) passes through a center of the frame (21).

Description

TECHNICAL FIELD

[0001] The present invention relates to a wind propulsion device.BACKGROUND

[0002] Patent Literature 1 discloses a wind powered sailing ship equipped with vertical blades, which are rotatable around a vertical shaft and configured in the form of a windmill, and a propeller connected to the vertical shaft. A trailing edge of the vertical blade is connected to a wire extending from an axis that is disposed eccentrically to the rotation axis of a leading edge of the vertical blade in a downwind direction. The vertical blades are each configured to pivot freely around the rotational axis of its leading edge. Patent Literature 2 discloses a wind power generator including a main shaft extending in the vertical direction, an upper bearing provided on the upper portion of the main shaft, a lower bearing provided on the lower portion of the main shaft, a frame connected to the main shaft via the upper and lower bearings, blades attached to the main shaft, a motor shaft connected to the main shaft via the lower bearing, and a generator connected to the motor shaft.RELEVANT REFERENCE LIST OF RELEVANT PATENT LITERATURE

[0003] Patent Literature 1: Japanese Patent Application Publication No. Hei 6-199287 Patent Literature 2: Chinese Patent Application Publication No. 101684778 SUMMARY

[0004] In a sailing ship intended to be propelled by wind as in Patent Literature 1 and provided with vertical blades that rotate around a main shaft extending in the vertical direction as in Patent Literature 2, a circular pillar may be provided in the middle to reduce wobbling of the rotation axis. If the circular pillar is made excessively thick in order to increase strength and rigidity, the aerodynamic characteristics, consisting of lift and rotational force, will deteriorate. It should be noted that the aerodynamic characteristics are the combination of lift (a force perpendicular to the wind, i.e., Magnus force) and rotational force (power generation energy, natural rotational speed, and no-load rotational speed).

[0005] The present invention is intended to overcome the above problem, and one object thereof is to provide a wind propulsion device having improved aerodynamic characteristics.

[0006] To overcome the above problem, aspects of the present invention are configured as follows. (1) A wind propulsion device according to an aspect of the present invention is a wind propulsion device installed on a movable body and configured to generate propulsive force by receiving wind, the wind propulsion device comprising: a rotator including a frame having an annular shape around a rotation axis, the rotator being rotatable around the rotation axis; and a plurality of blades each fixed to the frame, the plurality of blades being provided such that imaginary straight lines connecting respective opposite ends in a direction orthogonal to the rotation axis are parallel, wherein the plurality of blades include a central blade, and an imaginary straight line connecting opposite ends of the central blade passes through a center of the frame.

[0007] According to this configuration, the central blade provided at the center of the frame improves aerodynamic characteristics compared to the case where nothing or a circular pillar is at the center of the frame.

[0008] (2) In the wind propulsion device according to (1) above, the central blade may have a closed cross-section in a cross-sectional view intersecting an axial direction along the rotation axis.

[0009] (3) In the wind propulsion device according to (1) above, the frame may be made of a rigid material, and the plurality of blades may be made of a non-rigid material.

[0010] (4) In the wind propulsion device according to (1) or (2) above, as viewed from an axial direction along the rotation axis, the central blade may include: a central pillar provided at the center of the frame; and a blade body made of resin, the blade body being disposed to cover the central pillar.

[0011] (5) In the wind propulsion device according to (1) or (2) above, as viewed from an axial direction along the rotation axis, the central blade may include: a central pillar provided at the center of the frame; a pair of struts provided at opposite ends of the imaginary straight line; and a blade body formed of fabric stretched over the pair of struts and the central pillar.

[0012] (6) In the wind propulsion device according to (1) or (2) above, as viewed from an axial direction along the rotation axis, the central blade may include: a pair of struts provided at opposite ends of the imaginary straight line; and a blade body formed of fabric stretched over the pair of struts.

[0013] (7) In the wind propulsion device according to any one of (1) to (6) above, the plurality of blades other than the central blade may be curved radially outward with respect to the imaginary straight lines.

[0014] (8) In the wind propulsion device according to any one of (1) to (7) above, the rotator may further include a beam shaped like a propeller, the beam being connected at opposite ends thereof to an inner circumference of the frame and connecting the plurality of blades together.

[0015] (9) In the wind propulsion device according to any one of (1) to (8) above, the plurality of blades may be disposed so that respective opposite ends are located on an imaginary circle around the rotation axis.

[0016] (10) In the wind propulsion device according to any one of (1) to (9) above, as viewed from an axial direction along the rotation axis, the plurality of blades may be disposed so as to be line symmetrical with respect to a center line that passes through the center of the frame and is parallel to the imaginary straight lines.

[0017] (11) In the wind propulsion device according to any one of (1) to (10) above, as viewed from an axial direction along the rotation axis, the plurality of blades may be disposed so as to be line symmetrical with respect to a center line that passes through the center of the frame and is orthogonal to the imaginary straight lines.

[0018] (12) In the wind propulsion device according to any one of (1) to (11) above, as viewed from an axial direction along the rotation axis, those among the plurality of blades that are disposed closer to the center of the frame may each extend so that a length of the imaginary straight line is at least 1 / 2 a diameter of the frame.

[0019] (13) In the wind propulsion device according to any one of (1) to (12) above, each of the plurality of blades may have a twisted shape such that a first imaginary straight line, which connects opposite ends of each of the plurality of blades at a first position on the rotation axis, and a second imaginary straight line, which connects opposite ends of each of the plurality of blades at a second position on the rotation axis different from the first position, intersect with each other as viewed from an axial direction along the rotation axis.ADVANTAGEOUS EFFECTS

[0020] The present invention improves the aerodynamic characteristics.BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Fig. 1 is a perspective view showing a wind propulsion system according to a first embodiment. Fig. 2 is a diagram showing an example of functional configuration of the wind propulsion system according to the first embodiment. Fig. 3 is a diagram showing an example of flow of energy and the like in the wind propulsion system, along with a comparative example. Fig. 4 is a perspective view showing a wind propulsion device according to a first embodiment. Fig. 5 is a top perspective view showing a first position of a plurality of blades in the wind propulsion device according to the first embodiment. Fig. 6 is a top perspective view showing a second position of a plurality of blades in the wind propulsion device according to the first embodiment. Fig. 7 shows comparison of the effects (lift, drag, and rotational force) for the number of blades. Fig. 8 shows comparison of the effects (lift, drag, and rotational force) for the shape of blades. Fig. 9 shows comparison of the effects (lift, drag, and rotational force) of the central blade. Fig. 10 is a perspective view showing a wind propulsion device according to a second embodiment. Fig. 11 is a schematic view showing a central blade of the wind propulsion device according to the second embodiment. Fig. 12 is a schematic view showing a central blade of the wind propulsion device according to the third embodiment. Fig. 13 shows a wind propulsion device according to a fourth embodiment as viewed from a vertical direction. DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Embodiments of a wind propulsion device and a wind propulsion system according to the present invention will now be described with reference to the accompanying drawings. In the following description, terms such as "parallel," "orthogonal," "center" and "coaxial" describe relative or absolute positions. These terms not only strictly mean such positions but also allow some tolerances and relative differences in angle and distance as long as the same effects can be still produced. In the drawings used for the following description, members are shown to different scales into recognizable sizes.<Wind Propulsion System>

[0023] Fig. 1 is a perspective view showing a wind propulsion system 100 according to a first embodiment. Fig. 2 is a diagram showing an example of functional configuration of the wind propulsion system 100 according to the first embodiment. Referring to Figs. 1 and 2 together, the wind propulsion system 100 includes a wind propulsion device 1, which is installed on a ship 2 (an example of a movable body) to generate propulsive force by receiving wind, and a windmill sail controller 140 (an example of a wind power controller) for controlling the wind propulsion device 1.

[0024] The wind propulsion device 1 includes a windmill sail body 111 that can rotate around a rotation axis RC (see Fig. 4) extending vertically from the hull 3. The wind propulsion device 1 further includes an electric motor 41 that rotates the windmill sail body 111. The windmill sail body 111 is equipped with an assembly 4 that includes a plurality of blades 10A to 10I that are shaped like a plate and connected together so as to be integrally rotatable around a rotation axis.

[0025] The wind propulsion device 1 includes a rotator 20A, 20B, which has a frame 21 formed in an annular shape around the rotation axis RC and is rotatable around the rotation axis RC, and a plurality of blades 10A to 10I each being fixed to the frame 21 and arranged such that imaginary straight lines connecting respective opposite ends of the blades in a direction orthogonal to the rotation axis RC are parallel (see Fig. 4). The plurality of blades 10A to 10I include a central blade 10A. The imaginary straight line connecting the opposite ends of the central blade 10A passes through the center of the frame 21. The rotator 20A, 20B having the frame 21, and the plurality of blades 10A to 10I constitute the assembly 4.

[0026] The wind power controller 140 includes a speed meter 65 for acquiring the moving speed of the ship 2, a detection unit 7 for acquiring wind condition information including the current wind speed and wind direction in the area where the ship 2 is located, a calculation unit 126 for calculating the relative wind direction on the wind propulsion device 1 based on the acquired moving speed of the ship 2 and the wind condition information, and a rotation control unit 40 for controlling the electric motor 41 to adjust the rotation speed of the windmill sail body 111 according to the calculated relative wind direction. The wind propulsion device 1, which is included in the wind propulsion system 100, serves as a windmill sail that propels the ship 2 by generating a lift when receiving the wind.

[0027] The wind propulsion system 100 includes: the above-mentioned wind propulsion device 1 having the windmill sail body 111, the detection unit 7, a receiving unit 8, and the rotation control unit 40; a remote control device 120 equipped with an operation unit 121 that is operated to control a propulsion speed of the ship 2, and a determination unit 134 that determines a target thrust of the wind propulsion device 1 and a target thrust of a propeller 51 driven by a prime mover 50 attached to the ship 2 in accordance with an operation position of the operation unit 121; a windmill sail controller 140 that controls the rotational speed of the windmill sail body 111 rotating around the rotation axis in accordance with the target thrust of the wind propulsion device 1; and a prime mover controller 150 that controls a rotational speed of the prime mover 50 in accordance with the target thrust of the propeller 51. The wind propulsion system 100 constitutes a system (ship integrated propulsion system) that performs integrated control of two types of propulsion: propulsion by the wind propulsion device 1 and propulsion by the propeller 51 driven by the prime mover 50.

[0028] The ship 2 is equipped with the remote control device 120, the prime mover 50, a shaft 52, the propeller 51, a shaft horsepower meter 55, a detection system 60, the speed meter 65, and the prime mover controller 150. Note that the ship 2 is not necessarily a ship operated by crew members. For example, the ship 2 may be a ship capable of autonomous navigation.

[0029] The remote control device 120 executes a program (hereinafter referred to as a "ship control program") that controls the operation of the ship 2. The remote control device 120 functions, by executing the ship control program, as a device that includes a central control unit 130, the operation unit 121, a communication unit 122, an output unit 123, the calculation unit 126, and a storage unit 124. The remote control device 120 includes the central control unit 130 that controls operations of each functional unit of the remote control device 120.

[0030] The central control unit 130 includes, for example, a memory 132 and a processor 131 such as a CPU (Central Processing Unit) that are connected to each other via a bus. The processor 131 reads a ship control program stored in the storage unit 124 and stores the read ship control program in the memory 132. The processor 131 executes the ship control program stored in the memory 132.

[0031] The central control unit 130 communicates with the prime mover controller 150 by controlling the operation of the communication unit 122, for example. The central control unit 130 obtains information inputted via the operation unit 121, for example. The central control unit 130 records information generated by the execution of the ship control program in the storage unit 124, for example. The central control unit 130 obtains, for example, the number of revolutions of the prime mover 50. The central control unit 130 outputs, for example, the obtained number of revolutions to the prime mover controller 150. In the following description, an actual value of the number of revolutions of the prime mover 50 obtained (determined) by the central control unit 130 is also referred to as an "actual number of revolutions."

[0032] The operation unit 121 is a steering handle used to control both the speed and traveling direction of the ship 2. The operation unit 121 receives input from a crew. The crew inputs either one or both of a target number of revolutions or a rotational direction of an engine into the remote control device 120 by operating the operation unit 121. The target number of revolutions is a target number of revolutions of the prime mover 50. The rotational direction of the engine is the rotational direction of the prime mover 50. The rotational direction of the prime mover 50 is either forward or reverse. The traveling direction of the ship 2 with the prime mover 50 rotating in the forward direction is opposite to the traveling direction of the ship 2 with the prime mover 50 rotating in the reverse direction.

[0033] The operation unit 121 outputs the target number of revolutions indicated by the result of the crew's operation into the central control unit 130. The operation unit 121 outputs information indicating the engine rotational direction indicated by the result of the crew's operation (hereinafter referred to as "rotational direction information") to the central control unit 130. Note that the operation unit 121 does not necessarily need to be operated by crews. For example, when the ship 2 operates autonomously, the operation unit 121 may be operated by the central control unit 130 in accordance with a ship control program.

[0034] The communication unit 122 includes a communication interface for connecting the remote control device 120 to the shaft horsepower meter 55, the detection system 60, the speed meter 65, and the prime mover controller 150. The communication unit 122 communicates with the shaft horsepower meter 55, the detection system 60, the speed meter 65, and the prime mover controller 150 via either wired or wireless communication. The communication unit 122 transmits, for example, the target number of revolutions, the actual number of revolutions, and the rotational direction information to the prime mover controller 150.

[0035] The output unit 123 includes output devices such as display devices including CRT (Cathode Ray Tube) displays, liquid crystal displays, and organic EL (Electro-Luminescence) displays, as well as audio output devices such as speakers. The output unit 123 may be configured as an interface for connecting these output devices to the device in which the output unit is included. The output unit 123 outputs information related to the remote control device 120. The output unit 123 outputs, for example, results of operations performed via the operation unit 121.

[0036] The calculation unit 126 includes a processor such as a CPU (Central Processing Unit) (an example of a processing unit) connected by a bus. The calculation unit 126 calculates various information related to the remote control device 120. The calculation unit 126 calculates, for example, the relative wind direction on the wind propulsion device 1 based on the obtained traveling speed of the ship 2 and wind condition information.

[0037] The storage unit 124 is formed of storage devices such as magnetic hard disk devices and semiconductor storage devices. The storage unit 124 stores various information related to the remote control device 120. The storage unit 124 stores, for example, a ship control program in advance. The storage unit 124 stores information generated by execution of the ship control program, for example. The storage unit 124 stores, for example, a history of operations performed by crew members through the operation unit 121. The storage unit 124 stores, for example, a history of the actual number of revolutions of the prime mover 50.

[0038] The prime mover 50 is an engine that generates propulsive force for the ship 2. The prime mover 50 converts the energy contained in fuel into motive power. Any types of fuel and operating mechanism can be used provided that the prime mover 50 is able to convert the energy contained in fuel into the motive power. The prime mover 50 is, for example, a two-stroke diesel engine. Alternatively, the prime mover 50 may be, for example, a four-stroke diesel engine or a gas engine. For the sake of explanatory convenience, an example of the ship 2 in which the prime mover 50 is a two-stroke engine will be described.

[0039] The shaft 52 is rotated by the power produced by the prime mover 50. The number of rotations of the shaft 52 is proportional to the number of revolutions of the prime mover 50. The rotation of the shaft 52 transmits the power produced by the prime mover 50 to the propeller 51.

[0040] The propeller 51 is rotated by the power generated by the prime mover 50. The rotation of the propeller 51 produces the propulsive force that moves the ship 2.

[0041] The shaft horsepower meter 55 measures the power produced by the prime mover 50. The shaft horsepower meter 55 measures the power produced by the prime mover 50 by, for example, detecting a torsional strain produced in the shaft 52 by one or both of electrical and optical methods.

[0042] The detection system 60 includes a sensor that detects the number of revolutions of the prime mover 50. The detection system may include, for example, a proximity sensor. The proximity sensor may be configured to output an on-signal when metal is situated within a certain distance and an off-signal when metal is not situated within the certain distance. In this case, the proximity sensor outputs an on-signal when, for example, a convex portion provided on the surface of the shaft 52 is situated within a detection range and an off-signal when a concave portion provided in the surface of the shaft 52 is situated within the detection range. The detection system 60 may detect the number of revolutions of the prime mover 50 based on such changes in the output of the proximity sensor and the information obtained in advance indicating the interval between the concave portion and convex portion of the shaft 52.

[0043] The detection system 60 may include other types of devices, in place of the proximity sensor. For example, the detection system 60 may include an encoder, a sensor that detects engine sound, or a sensor that detects engine vibration.

[0044] The speed meter 65 measures the speed of the ship 2. The speed meter 65 uses, for example, the Doppler effect for measuring the speed of the ship. The ship speed measured by the speed meter 65 is specifically the ship's speed relative to the water.

[0045] The prime mover controller 150 controls the operation of the prime mover 50. The prime mover controller 150 determines the amount of the fuel to be injected and the timing of the fuel injection based on the actual number of revolutions obtained by the determination unit 134. The prime mover controller 150 controls the operation of the prime mover 50 so that the determined amount of fuel is injected at the determined timing. The prime mover controller 150 controls the operation of the prime mover 50 by executing a fuel feed calculation process, fuel feed control process, and rotational direction control process.

[0046] In the fuel feed calculation process, the amount of fuel to be fed to the prime mover 50 (hereinafter also referred to as "fuel feed") is calculated based on the target number of revolutions and the actual number of revolutions, using a predetermined fuel feed calculation function. The fuel feed calculation function is a function that uses the target number of revolutions and the actual number of revolutions as explanatory variables, and the fuel feed as an objective variable. The prime mover controller 150 calculates the fuel feed by executing the fuel feed calculation process.

[0047] In the fuel feed control process, the degree of opening and closing of a valve attached to a fuel feed pipe is controlled so that the fuel feed calculated by the fuel feed calculation process is accomplished to the prime mover 50. The fuel feed pipe is a pipe connecting the prime mover 50 and an unshown fuel tank, through which the fuel flows from the fuel tank to the prime mover 50. The prime mover controller 150 feeds the fuel from the fuel tank to the prime mover 50 by executing the fuel feed control process.

[0048] In the rotational direction control process, the rotational direction of the prime mover 50 is controlled to the rotational direction of the engine. The rotational direction control process is, for example, a process of switching the rotational direction of the prime mover 50 between forward and reverse by operating a clutch of the prime mover 50. The prime mover controller 150 controls the rotational direction of the prime mover 50 to the rotational direction of the engine by executing the rotational direction control process.

[0049] The direction of a torque outputted by the prime mover 50 is in accordance with the rotational direction of the prime mover 50. Therefore, the direction of the torque occurring when the rotational direction of the prime mover 50 is forward is opposite to the direction of the torque occurring when the rotational direction of the prime mover 50 is reverse. The power produced by the prime mover 50 is equal to the value obtained by multiplying the magnitude of the torque outputted from the prime mover 50 by the number of revolutions of the prime mover 50.

[0050] The central control unit 130 is further provided with an obtaining unit 133 and the determination unit 134. The obtaining unit 133 obtains the results of detections performed by the detection system 60 via the communication unit 122. The determination unit 134 obtains the power measured by the shaft horsepower meter 55 via the communication unit 122. The obtaining unit 133 obtains the ship speed measured by the speed meter 65 via the communication unit 122. The obtaining unit 133 obtains the fuel feed calculated by the prime mover controller 150 via the communication unit 122. The obtaining unit 133 obtains the target number of revolutions and the rotational direction information outputted by the operation unit 121 via the communication unit 122.

[0051] The determination unit 134 executes a number-of-revolutions determination process. The number-of-revolutions determination process determines the actual number of revolutions of the prime mover 50 from one of values of the number of revolutions obtained by the detection system 60, based on at least one of the target number of revolutions, state information, which is information about the state of the prime mover 50, or the speed of the ship 2. Examples of the possible actual number of revolutions include a first number of revolutions and a second number of revolutions. The state information includes, for example, the fuel feed. The state information includes, for example, the power measured by the shaft horsepower meter 55.

[0052] The central control unit 130 outputs the actual number of revolutions determined by the determination unit 134 to the prime mover controller 150 via the communication unit 122. The central control unit 130 outputs the rotational direction information to the prime mover controller 150 via the communication unit 122. The central control unit 130 outputs the target number of revolutions to the prime mover controller 150 via the communication unit 122. The central control unit 130 controls the operation of the output unit 123 and causes the output unit 123 to output information.<Flow of Energy in Wind Propulsion System>

[0053] Fig. 3 is a diagram showing an example of flow of energy and the like in the wind propulsion system 100, along with a comparative example. In Fig. 3, the flow of physical objects, the flow of information, and the electrical flow (an example of a flow of energy and the like) are indicated by various arrows.

[0054] As shown in Fig. 3, in the comparative example (conventional system), the force of the wind is once converted to rotational force to turn the propeller. Therefore, in the comparative example, the force conversion results in a reduction of propulsion efficiency. In contrast, the wind propulsion system 100 of the embodiment has the windmill sail regarded as a propeller and uses directly as a propulsive force the lift (Magnus force) generated by the windmill sail rotating with the force of the wind. In other words, the wind propulsion system 100 of the embodiment uses the wind directly as a propulsive force. Therefore, the wind propulsion system 100 of the embodiment provides an improved propulsion efficiency compared to the comparative example.

[0055] Thus, in the wind propulsion system 100 of the embodiment, the wind is received by the windmill sail and converted into a propulsive force. For example, just as a sailing ship receives the wind in its sails and converts it into a propulsive force, a windmill sailing ship converts the wind directly into a propulsive force with its windmill sail. The wind propulsion system 100 of the embodiment is characterized by converting the wind into a propulsive force as a sailing ship. In the wind propulsion system 100 of the embodiment, the performance of the windmill sail as a sail is superior to that of a conventional rigid-wing sail.<Electric Motor>

[0056] Referring to Figs. 2 to 4, the rotation control unit 40 includes an electric motor 41 capable of rotationally driving the windmill sail body 111. The electric motor 41 enables both the driving of the rotation of the windmill sail body 111 around a rotation axis and the acceleration and deceleration of the rotation of the windmill sail body 111. In other words, the electric motor 41 enables both the driving of the rotation of the blades 10A to 10H around the rotation axis and the acceleration and deceleration of the rotation of the blades 10A to 10H around the rotation axis.<Brake Unit>

[0057] The wind propulsion system 100 further includes a brake unit 45 that brakes the rotation of the blades 10A to 10H around the rotation axis when the wind speed exceeding a threshold is detected by the detection unit 7. The brake unit 45 reduces the rotation speed of the blades 10A to 10H by braking the rotation of the blades 10A to 10H around the rotation axis during strong winds, thereby reducing the lift. Induced drag can also be reduced by reducing the lift during headwinds.<Energy Storage Unit>

[0058] The wind propulsion system 100 further includes an energy storage unit 46 that stores regenerative energy generated by the electric motor 41 when the rotation around the rotation axis is decelerated. With this configuration, it is possible to utilize the regenerative energy of the electric motor 41 stored in the energy storage unit 46. For example, the energy storage unit 46 may be configured to include a battery, capacitor, etc.

[0059] As described above, the windmill sail functions as a sail that converts the wind force into a propulsive force, and also operates as a generator capable of converting excess wind energy into electricity when the wind force exceeds propulsion commands. For example, the generated electricity may be used during propulsion or for general purposes such as lighting.<Obtaining Unit>

[0060] The wind propulsion system 100 further includes the obtaining unit 133 that obtains the wind speed and wind direction of the wind currently occurring. When the rotation speed of the blades 10A to 10H, which rotate only by the wind currently occurring, is below a threshold value, the rotation control unit 40 increases the rotation speed of the blades 10A to 10H rotating around the rotation axis, using the electric motor 41. For example, when the thrust that can be generated by the windmill sail rotating without energy supply based on the current wind speed and wind direction is insufficient to meet a thrust command, the thrust can be amplified by accelerating the rotation using the power of the electric motor 41.

[0061] For example, the threshold value for the rotational speed of the blades 10A to 10H (an example of a threshold value for the blade rotational speed) is calculated based on the thrust command. For example, the optimal rotational speed can be calculated from the thrust command, and based on that calculation result, the rotational speed of the blades 10A to 10H can be increased by the electric motor 41.<Relationship Between Windmill Sail Control And Prime Mover Control>

[0062] The thrust that the windmill sail ship can generate without auxiliary power is limited. Accordingly, any shortfall in the thrust occurring without auxiliary power may be compensated by the drive mode of the windmill sail (the rotational driving of the blades 10A to 10H). For example, any shortfall in the thrust occurring with the drive mode of the windmill sail may be compensated by the propeller 51 (propeller drive).

[0063] For example, the central control unit 130 calculates the optimal rotation speed of the blades 10A to 10H rotating around the rotation axis based on the received thrust command and the results of detection of the wind direction and wind speed conducted when the thrust command was received. For example, when controlling the rotational speed of the blades 10A to 10H, vector control can be used to control the q-axis current, enabling seamless control regardless of whether to drive or brake the blades. For example, the central control unit 130 may link the blades 10A to 10H and the propeller 51 and adjust the thrust ratio between the windmill sail and the propeller 51 to maximize energy efficiency.

[0064] As described above, the wind propulsion system 100 is a system that converts the wind force into thrust. For example, when a thrust command value is received from the remote control device 120, the optimal rotation speed of the blades 10A to 10H is calculated based on the wind direction and the wind speed so that the specified thrust is generated. Then, the electric motor 41 is controlled so that the calculated rotation speed is achieved. The rotation speed referred to here includes the direction of rotation. In the case of reverse rotation, the electric motor 41 is controlled at a negative speed.

[0065] For example, when the natural thrust of the windmill sail ship alone is insufficient, the propeller 51 is also driven. Depending on the wind direction, when the wind propulsion device 1 is more efficient than the propeller 51, the electric motor 41 is driven to increase the rotation speed and thus the thrust. On the other hand, when the propeller 51 is more efficient than the wind propulsion device 1, the wind propulsion device 1 is set to free operation mode, and the propeller 51 is driven to generate thrust. Additionally, it is also possible to drive both the electric motor 41 of the wind propulsion device 1 and the propeller 51.

[0066] For example, multiple windmill sails can be arranged on the hull to adjust the rotational moment of the ship. For example, multiple windmill sails can be arranged at the front and rear of the hull, and the rotational speeds can be made different between the front and rear windmill sails. This allows the forces acting in the lateral direction of the ship to be set to different values between the front and rear windmill sails, thereby generating a moment.<Steering Gear Control Unit>

[0067] Referring to Fig. 2, the wind propulsion system 100 further includes a steering gear control unit 125. When the rotation control unit 40 changes the rotational speed of the blades 10A to 10H around the rotation axis, the steering gear control unit 125 controls the steering gear to steer to a direction opposite to the inertial force generated in a direction opposite to the direction of changing the rotational speed of the blades 10A to 10H. By anticipating that the torque caused by the inertial force would impose on the hull 3, the steering gear control unit 125 cooperates with a rudder to counteract the torque and thus prevent the hull 3 from rotating.

[0068] For example, when changing the rotational speed of the blades 10A to 10H by driving or braking, it may cooperate with the rudder. For example, when the electric motor 41 is in a free state and the blades 10A to 10H are rotating freely, it may not be necessary to cooperate with the rudder. For example, when braking or driving to change the rotational speed of the blades 10A to 10H, torque may act on the hull 3, causing the hull 3 to rotate. To prevent this, when only one wind propulsion device 1 is installed, it is desirable to cooperate with the rudder to account for the torque acting on the hull 3, thereby preventing the hull 3 from rotating.<Wind Propulsion Device>

[0069] Referring to Figs. 1 and 2 together, the wind propulsion device 1 serves as a windmill sail which is installed on the ship 2 to generate propulsive force by receiving wind. In the illustrated example, a single wind propulsion device 1 is installed on the front part (bow) of the hull 3. The installation configuration (installation location, number of devices, etc.) of the wind propulsion device 1 is not limited to the above and can be modified in accordance with the design specifications.<Windmill Sail Body>

[0070] Fig. 4 is a perspective view showing a windmill sail body 111 in the wind propulsion device 1 according to the first embodiment. Referring to Fig. 4, the wind propulsion device 1 includes the windmill sail body 111 that can rotate around the rotation axis RC (represented by the chain line in Fig. 4) extending vertically from the hull 3. The windmill sail body 111 includes the assembly 4, which is constituted by the rotator 20A, 20B rotatable around the axis RC and a plurality of blades 10A to 10I each shaped like a plate and fixed to the rotator 20A, 20B.

[0071] The rotator 20A, 20B has the frame 21 having an annular shape and located around the rotation axis RC and is rotatable around the rotation axis RC. In the illustrated example, the rotator 20A, 20B include a lower plate 20A, to which the lower ends of the plurality of blades 10A to 10I are fixed, and an upper plate 20B, to which the upper ends of the plurality of blades 10A to 10I are fixed.

[0072] The plurality of blades 10A to 10I are each fixed to the frame 21 so that the imaginary straight lines connecting their respective opposite ends in a direction orthogonal to the rotation axis RC are parallel. The plurality of blades 10A to 10I include a central blade 10A. The imaginary straight line connecting the opposite ends of the central blade 10A passes through the center of the frame 21. The plurality of blades 10A to 10I are disposed so that their respective opposite ends are located on an imaginary circle around the rotation axis RC. The axial direction along the rotation axis RC is vertical.

[0073] Viewed from the vertical direction, those among the plurality of blades 10A to 10I that are disposed closer to the center of the frame 21 extend so that the length of the imaginary straight line is at least 1 / 2 the diameter of the frame 21. In the illustrated example, those among the plurality of blades 10A to 10I that are disposed closer to the center of the frame 21 are other than the outermost one of the plurality of blades 10A to 10I. The length of the imaginary straight line is the length from one end of the blade to the other, or what is called chord length. The outermost one of the plurality of blades 10A to 10I may have a chord length less than 1 / 2 the diameter of the frame 21 (an imaginary circle around the rotation axis RC). Note that the chord lengths of the plurality of blades 10A to 10I are not limited to the above and may be modified in accordance with the design specifications.

[0074] In the illustrated example, the frame 21 (an imaginary circle around the rotation axis RC) is a perfect circle as viewed from the vertical direction. Note that the shape of the imaginary circle as viewed from the vertical direction is not limited to the above, but may also be elliptical, oblong, or a closed ring formed by connecting curves.

[0075] The rotator 20A, 20B further includes a beam 22 shaped like a propeller that is connected at both ends thereof to the inner circumference of the frame 21 and that connects the plurality of blades 10A to 10I together. In the illustrated example, the beam 22 passes through the center of the frame 21 and is connected at both ends thereof to the inner circumference of the frame 21. The rotator 20A, 20B has two beams 22, one each for the lower frame 20A and the upper frame 20B. Note that the configuration (number and arrangement, etc.) of the beams 22 is not limited to the above and can be modified in accordance with the design specifications.

[0076] The central blade 10A is disposed such that the imaginary straight line connecting the opposite ends of the central blade 10A passes through the center of the frame 21. The central blade 10A has a closed cross-section in the cross-sectional view (cross-sectional view intersecting the axial direction along the rotation axis RC). In the illustrated example, the central blade 10A has hollow structure. Note that the central blade 10A may have solid structure.

[0077] As viewed from the vertical direction, the central blade 10A has a central pillar 71 provided at the center of the frame 21, and a blade body 70 made of resin disposed to cover the central pillar 71. The central pillar 71 is coaxial with the rotation axis RC. The blade body 70 is made of FRP (Fiber Reinforced Plastics), for example. The blade body 70 may be made of metal, wood, other resins, or a composite of wood and resin.

[0078] In the illustrated example, the plurality of blades 10A to 10I, including the central blade 10A, are made of FRP (resin). It is also possible that the blades other than the central blade 10A are made of fabric, and only the central blade 10A is made of FRP (resin).

[0079] Of the plurality of blades 10A to 10I, the blades 10B to 10I other than the central blade 10A are curved radially outward with respect to the imaginary straight lines. In other words, viewed from the vertical direction, the blades 10B to 10I on the outer side of the central blade 10A are formed in a camber shape that curves radially outward with respect to their respective imaginary straight lines. In the illustrated example, the eight blades 10B to 10I, other than the center blade 10A, are formed in a camber shape. Note that the blades 10B to 10I, other than the center blade 10A, may be uncambered (elliptical or thin).

[0080] In the example shown in Fig. 4, the assembly 4 has a single stage; however, this embodiment is not limited thereto, and the number of stages of the assembly 4 can be modified in accordance with the design specifications. In the example shown in Fig. 1, there are multiple (e.g., three) assemblies 4A to 4C provided along the vertical direction. For example, if assemblies 4A and 4B are provided, the assemblies 4A and 4B may have a common rotator 20A, 20B. The installation configuration of the rotator 20A, 20B with respect to a plurality of assemblies 4 may be varied in accordance with the design specifications. Furthermore, the assemblies 4A and 4B may have the same shape, and the rotator 20A, 20B may be bolted or welded.

[0081] Fig. 5 is a top perspective view showing a first position of a plurality of blades 10A to 10I in the wind propulsion device according to the first embodiment. Fig. 6 is a top perspective view showing a second position of a plurality of blades 10A to 10I in the wind propulsion device according to the first embodiment. In Figs. 5 and 6, the upper frame and other members included in the assembly are not shown.

[0082] Referring to Figs. 5 and 6 together, each of the plurality of blades 10A to 10I has a twisted shape so that a first imaginary straight line (such as the first imaginary straight line FL1 for the central blade 10A shown in the drawing), which connects both ends of the blade at a first position on the rotation axis RC (represented by the chain line in the drawing), and a second imaginary straight line (such the second imaginary straight line FL2 for the central blade 10A shown in the drawing), which connects both ends of the blade at a second position different from the first position on the rotation axis RC, intersect each other as viewed from the vertical direction.

[0083] In the illustrated example, the nine blades are twisted so that the first imaginary straight line FL1 at the first position on the rotation axis RC and the second imaginary straight line FL2 at the second position on the rotation axis RC intersect when viewed from the vertical direction. In other words, each of the nine blades has a twisted shape such that cross-sections thereof orthogonal to the vertical direction are the same at any position on the rotation axis RC. It should be noted that the manner of twisting (such as the shape) of the plurality of blades 10A to 10I is not limited to the above and may be modified in accordance with the design specifications.<Comparison of Effects for Number of Blades>

[0084] Fig. 7 shows comparison of the effects (lift, drag, and rotational force) for the number of blades. As shown in Fig. 7, mesh models (finite element models) were created for blade configurations with 5, 7, 9, 11, and 13 blades, respectively, and the effects for the number of blades (lift, drag, and rotational force) were compared through analysis. The results confirmed that the number of blades is optimal at the midpoint. Specifically, lift was largest for the 11-blade configuration, drag was largest for the 7-blade configuration, and rotational force was largest for the 11-blade configuration. The number of blades for which lift and drag are at their largest values varies depending on the size of the windmill sail, the thickness of the blades, and other conditions.<Comparison of Effects for Shape of Blades>

[0085] Fig. 8 shows comparison of the effects (lift, drag, and rotational force) for the shape of blades. Fig. 8 shows a circular pillar at the rotation center of the rotation axis. As shown in Fig. 8, mesh models (finite element models) were created for the elliptical blade, the first camber shape, and the second camber shape, respectively, and the effects for the shape of blades (lift, drag, and rotational force) were compared through analysis. The second camber shape is a shape in which the blades are more curved than in the first camber shape. The results confirmed that camber shapes increase lift but decrease rotational force.<Comparison of Effects of Central Blade>

[0086] Fig. 9 shows comparison of the effects (lift, drag, and rotational force) of the central blade. As shown in Fig. 9, mesh models (finite element models) were created for the following configurations: empty center, central circle, thin central blade, thick central blade, and central blade alone, respectively, and the effects of the central blade (lift, drag, and rotational force) were compared through analysis. The analysis conditions were as follows: a size of 4 meters in diameter and 40 meters in height of the windmill sail body, a wind speed of 10 m / s, and fixed rotation of the windmill sail at 54 rpm. The results confirmed that the optimum performance (lift, drag, and rotational force are all maximum values) is achieved with the thin central blade configuration.<Advantageous Effects>

[0087] As described above, the wind propulsion device 1 according to this embodiment is installed on the ship 2 and generates propulsive force by receiving wind. The wind propulsion device 1 includes a rotator 20A, 20B, which has a frame 21 formed in an annular shape around the rotation axis RC and is rotatable around the rotation axis RC, and a plurality of blades 10A to 10I each being fixed to the frame 21 and arranged such that imaginary straight lines connecting respective opposite ends of the blades in a direction orthogonal to the rotation axis RC are parallel. The plurality of blades 10A to 10I include a central blade 10A. The imaginary straight line connecting the opposite ends of the central blade 10A passes through the center of the frame 21.

[0088] According to this configuration, the central blade 10A provided at the center of the frame 21 improves aerodynamic characteristics compared to the case where nothing or a circular pillar is at the center of the frame 21.

[0089] The central blade 10A according to this embodiment has a closed cross-section in the cross-sectional view. This configuration improves rigidity compared to the case where the central blade 10A has an open cross-section in the cross-sectional view.

[0090] As viewed from the vertical direction, the central blade 10A according to this embodiment has a central pillar 71 provided at the center of the frame 21, and a blade body 70 made of resin disposed to cover the central pillar 71. This configuration improves the accuracy of the blade shape compared to the case where the central blade 10A is made of fabric, resulting in improved aerodynamic characteristics.

[0091] Of the plurality of blades 10A to 10I according to this embodiment, the blades 10B to 10I other than the central blade 10A are curved radially outward with respect to the imaginary straight lines. This configuration improves lift compared to the case where the blades other than the central blade 10A have an uncambered (elliptical) shape.

[0092] The rotator 20A, 20B according to this embodiment further includes a beam 22 shaped like a propeller that is connected at both ends thereof to the inner circumference of the frame 21 and that connects the plurality of blades 10A to 10I together. This configuration improves the aerodynamic characteristics compared to the case where the plurality of blades 10A to 10I are connected to each other by a horizontal rod.

[0093] The plurality of blades 10A to 10I according to this embodiment are disposed so that their respective opposite ends are located on an imaginary circle around the rotation axis RC. This configuration increases the propulsive force relative to the area occupied by the blades.

[0094] In the wind propulsion device 1 according to this embodiment, as viewed from the vertical direction, those among the plurality of blades 10A to 10I that are disposed closer to the center of the frame 21 extend so that the length of the imaginary straight line is at least 1 / 2 the diameter of the frame 21. This configuration increases the effect of accelerating and decelerating the wind in front and behind, and the Magnus effect improves the propulsive force relative to the area occupied by the blades.

[0095] Each of the plurality of blades 10A to 10I according to this embodiment has a twisted shape such that a first imaginary straight line FL1, which connects both ends of the blade at a first position on the rotation axis RC, and a second imaginary straight line FL2, which connects both ends of the blade at a second position on the rotation axis RC different from the first position, intersect with each other when viewed in the vertical direction. According to this configuration, the plurality of blades 10A to 10I have a shape twisted along the vertical direction, thus generating airflow along the vertical direction. Thus, induced drag (e.g., the effect of aspect ratio) can be reduced and, in turn, propulsion efficiency can be improved.<Second Embodiment>

[0096] The following describes a wind propulsion device 201 according to a second embodiment. In the following description, the parts having the same functions as in the first embodiment will have the same names and reference numerals, and their functions will not be specifically described.

[0097] Fig. 10 is a perspective view showing the wind propulsion device 201 according to the second embodiment. Fig. 11 is a schematic view showing a central blade 210A of the wind propulsion device 201 according to the second embodiment. Referring to Figs. 10 and 11 together, in the wind propulsion device 201 of the second embodiment, the central blade 210A includes a central pillar 71 provided at the center of the frame 21 as viewed from the vertical direction, a pair of struts 72 provided at both ends of the imaginary straight line, and a blade body 270 formed of fabric stretched over the pair of struts 72 and the central pillar 71.

[0098] The rotator 20A, 20B may include a horizontal rod 222 (rod-shaped beam) that is connected at both ends thereof to the inner circumference of the frame 21 and that connects the plurality of blades 210A to 210I together. The rotator 20A, 20B may have a plurality of wires 223 (tension structure) that are connected to the frame 21 and support the plurality of blades 210A to 210I, respectively. The blades 210B to 210I, other than the central blade 210A, may be formed of fabric stretched over the frame 21 and the wires 223.

[0099] In the illustrated example, the central pillar 71 has a cylindrical shape. Each of the pair of struts 72 has a cylindrical shape with a smaller diameter than the central pillar 71. The pair of struts 72 have the same shape. The fabric of the central blade 210A has a rhombic shape as viewed from the vertical direction. Note that the configuration (number, geometry, shape, etc.) of the plurality of blades 210A to 210I, including the central blade 210A, is not limited to the above and may be modified in accordance with the design specifications.

[0100] The central blade 210A according to this embodiment includes a central pillar 71 provided at the center of the frame 21 as viewed from the vertical direction, a pair of struts 72 provided at both ends of the imaginary straight line, and a blade body 270 formed of fabric stretched over the pair of struts 72 and the central pillar 71. This configuration reduces manufacturing costs compared to the case where the central blade 210A is made of FRP.<Third Embodiment>

[0101] The following describes a wind propulsion device according to a third embodiment. In the following description, the parts having the same functions as in the second embodiment will have the same names and reference numerals, and their functions will not be specifically described.

[0102] Fig. 12 is a schematic view showing a central blade 310A of the wind propulsion device according to the third embodiment. As shown in Fig. 12, in the wind propulsion device of the third embodiment, the central blade 310A includes, as viewed from the vertical direction, a pair of struts 72 provided at both ends of the imaginary straight line, and a blade body 370 formed of fabric stretched over the pair of struts 72.

[0103] In the illustrated example, the central blade 310A does not have the central pillar 71. The pair of struts 72 have a cylindrical shape. The pair of struts 72 have the same shape. The fabric of the central blade 310A is I-shaped (shaped like one straight line) as viewed from the vertical direction. Note that the configuration (number, geometry, shape, etc.) of the plurality of blades, including the central blade 310A, is not limited to the above and may be modified in accordance with the design specifications.

[0104] The central blade 310A according to this embodiment includes, as viewed from the vertical direction, a pair of struts 72 provided at both ends of the imaginary straight line, and a blade body 370 formed of fabric stretched over the pair of struts 72. This configuration reduces the weight and the manufacturing costs of the wind propulsion device compared to the case with the central pillar 71 included in the central blade 310A.<Fourth Embodiment>

[0105] The following describes a wind propulsion device 401 according to a fourth embodiment. In the following description, the parts having the same functions as in the first embodiment will have the same names and reference numerals, and their functions will not be specifically described.

[0106] Fig. 13 shows the wind propulsion device 401 according to the fourth embodiment as viewed from the vertical direction. As shown in Fig. 13, in the wind propulsion device 401 of the fourth embodiment, the plurality of blades 410A to 410I extend in the vertical direction. The frame 21 is made of a rigid material. The plurality of blades 410A to 410I are made of a non-rigid material.

[0107] The frame 21 is made of a material having a higher rigidity than the blades 410A to 410I. The frame 21 is made of, for example, metal, resin (e.g., FRP), wood, or a composite of at least two of these materials. The plurality of blades 410A to 410I are made of fabric, for example.

[0108] As viewed from the vertical direction, the plurality of blades 410A to 410I are disposed so as to be line symmetrical with respect to a center line CL1 that passes through the rotation center of the rotation axis RC and is parallel to the imaginary straight lines. As viewed from the vertical direction, the plurality of blades 410A to 410I are disposed so as to be line symmetrical with respect to a center line CL2 that passes through the rotation center of the rotation axis RC and is orthogonal to the imaginary straight lines.

[0109] The frame 21 according to this embodiment is made of a rigid material. The plurality of blades 410A to 410I are made of a non-rigid material. This configuration reduces manufacturing costs compared to the case where the plurality of blades 410A to 410I are made of a rigid material (e.g., FRP).

[0110] As viewed from the vertical direction, the plurality of blades 410A to 410I according to this embodiment are disposed so as to be line symmetrical with respect to the center line CL1 that passes through the center of the frame 21 and is parallel to the imaginary straight lines. According to this configuration, the center of gravity does not change even upon rotation, thus minimizing the centrifugal force exerted on the ship 2.

[0111] As viewed from the vertical direction, the plurality of blades 410A to 410I according to this embodiment are disposed so as to be line symmetrical with respect to the center line CL2 that passes through the center of the frame 21 and is orthogonal to the imaginary straight lines. According to this configuration, the characteristics of the obtained propulsive force remain the same regardless of the rotational direction of the blades, so the rotational direction can be changed to match the wind direction for propulsion.<Modifications>

[0112] The technical scope of the present invention is not limited to the embodiments described above but is susceptible of various modifications within the purport of the present invention.

[0113] The following describes other examples (modifications) of the movable body on which the wind propulsion device of the embodiments described above is installed. Sails of ships, airplane wings, rotor blades, and windmill blades have the same feature of generating lift, and the present invention can be applied to them with the effect of generating a large lift force (Magnus force) while also generating electricity. For example, the configuration of the embodiments described above can be applied to movable bodies moving at a high speed (e.g., high-speed ships, automobiles, etc.). The wind propulsion device may also be applied to the wings of flying bodies, or may also be applies to airplanes, drones, flying cars, etc. If water resistance is to be ignored, railroads may be used. For example, the wind propulsion device may be installed on railroad vehicles running on underutilized local lines. The windmill sail mechanism is not limited to wind and can be applied to other fluids. For example, electricity may be generated by moving a ship across ocean currents (ocean current power generation). Ocean currents are slower in speed, but they have a higher density compared to air. The Japan Current flows at approximately 2 meters per second, but considering that its density is about 1,000 times greater than that of air, it is equivalent to a wind blowing at 20 meters per second. For ships, power transmission is challenging, and the capacity for onboard energy storage is inherently limited. Therefore, it is feasible to construct a factory that consumes a large amount of electricity within a ship (i.e., a factory ship). Examples include hydrogen production and electrolytic refining of aluminum. In this case, electrical power can be directly transported to the demand site by ship. For example, the wind propulsion device may be installed on a railroad container. In this case, electrical power can be supplied to refrigerated containers and the like, and thus it is no longer necessary to provide electricity via pantographs. Furthermore, it can be electrically isolated from the railroad system, the risk of accidents can be reduced. It can also be used as a power source for the braking system of freight cars. Similarly, the wind propulsion device may be installed on truck containers or ship containers.

[0114] The functions of the control unit according to the embodiments described above may be implemented in a program stored on a computer-readable storage medium, and the program stored on the storage medium may be loaded onto a computer system that then executes the program for processing. The "computer system" mentioned above may include an operating system (OS) or hardware such as peripheral devices. The "computer-readable storage medium" mentioned above refers to a storage device such as a portable medium like a flexible disc, a magneto-optical disc, a ROM (Read Only Memory), a flash memory or other writable non-volatile memory, and a DVD (Digital Versatile Disc), and a hard disk built-in to the computer system.

[0115] Further, the "computer-readable storage medium" includes storage media that retain the program for some period of time, like a volatile memory (for example, DRAM (Dynamic Random Access Memory)) in an information processing device receiving the program through a network such as the Internet or a communication line such as a telephone line, or in a computer system that operates as a client. The program mentioned above may be transmitted from a computer system that includes a storage device or the like storing the program to another computer system through a transmission medium or by a transmission wave in a transmission medium. The "transmission medium" for transmitting the program refers to a medium that operates to transmit information, like a network (communication network) such as the Internet or a communication line (communication wire) such as the telephone line. Only a part of the functions described above may be implemented in the above program. Further, the functions described above may be implemented by a combination of the above program and other programs previously stored on the computer system. That is, the above program may be what is called a difference file (a difference program).

[0116] The elements of the embodiments described above may be replaced with known elements within the purport of the present invention. Further, the modifications described above may be combined. In the embodiments disclosed herein, a member formed of multiple components may be integrated into a single component, or conversely, a member formed of a single component may be divided into multiple components. Irrespective of whether or not the components are integrated, they are acceptable as long as they are configured to attain the object of the invention. According to the foregoing embodiments disclosed herein, a plurality of functions may be distributively provided. Some or all of these functions may be integrally provided. Conversely, a different plurality of functions may be integrally provided. Some or all of these functions can be distributively provided. Irrespective of whether the functions are integrally or distributively provided, they are acceptable as long as they are configured to attain the object of the invention.LIST OF REFERENCE NUMBERS

[0117] 1, 201, 401: wind propulsion device; 2: ship (movable body); 10A to 10I, 210A to 210I, 410A to 410I: blade; 10A, 210A, 310A: central blade; 20A, 20B: rotator; 21: frame; 22: beam; 70, 270, 370: blade body; 71: central pillar; 72: strut; CL1, CL2: center line; FL1, FL2: imaginary straight line; RC: rotation axis

Claims

1. A wind propulsion device (1) installed on a movable body (2) and configured to generate propulsive force by receiving wind, the wind propulsion device (1) comprising: a rotator (20A, 20B) including a frame (21) having an annular shape around a rotation axis (RC), the rotator (20A, 20B) being rotatable around the rotation axis (RC); and a plurality of blades (10A to 10I) each fixed to the frame (21), the plurality of blades (10A to 10I) being provided such that imaginary straight lines connecting respective opposite ends in a direction orthogonal to the rotation axis (RC) are parallel, wherein the plurality of blades (10A to 10I) include a central blade (10A), and an imaginary straight line connecting opposite ends of the central blade (10A) passes through a center of the frame (21).

2. The wind propulsion device (1) of claim 1, wherein the central blade (10A) has a closed cross-section in a cross-sectional view intersecting an axial direction along the rotation axis (RC).

3. The wind propulsion device (1) of claim 1, wherein the frame (21) is made of a rigid material, and wherein the plurality of blades (10A to 10I) are made of a non-rigid material.

4. The wind propulsion device (1) of claim 1 or 2, wherein as viewed from an axial direction along the rotation axis (RC), the central blade (10A) includes: a central pillar (71) provided at the center of the frame (21); and a blade body (70) made of resin, the blade body (70) being disposed to cover the central pillar (71).

5. The wind propulsion device (201) of claim 1 or 2, wherein as viewed from an axial direction along the rotation axis (RC), the central blade (210A) includes: a central pillar (71) provided at the center of the frame (21); a pair of struts (72) provided at opposite ends of the imaginary straight line; and a blade body (270) formed of fabric stretched over the pair of struts (72) and the central pillar (71).

6. The wind propulsion device of claim 1 or 2, wherein as viewed from an axial direction along the rotation axis (RC), the central blade (310A) includes: a pair of struts (72) provided at opposite ends of the imaginary straight line; and a blade body (370) formed of fabric stretched over the pair of struts (72).

7. The wind propulsion device (1) of any one of claims 1 to 3, wherein the plurality of blades (10A to 10I) other than the central blade (10A) are curved radially outward with respect to the imaginary straight lines.

8. The wind propulsion device (1) of any one of claims 1 to 3, wherein the rotator (20A, 20B) further includes a beam (22) shaped like a propeller, the beam (22) being connected at opposite ends thereof to an inner circumference of the frame (21) and connecting the plurality of blades (10A to 10I) together.

9. The wind propulsion device (1) of any one of claims 1 to 3, wherein the plurality of blades (10A to 10I) are disposed so that respective opposite ends are located on an imaginary circle around the rotation axis (RC).

10. The wind propulsion device (401) of any one of claims 1 to 3, wherein as viewed from an axial direction along the rotation axis (RC), the plurality of blades (410A to 410I) are disposed so as to be line symmetrical with respect to a center line (CL1) that passes through the center of the frame (21) and is parallel to the imaginary straight lines.

11. The wind propulsion device (401) of any one of claims 1 to 3, wherein as viewed from an axial direction along the rotation axis (RC), the plurality of blades (410A to 410I) are disposed so as to be line symmetrical with respect to a center line (CL2) that passes through the center of the frame (21) and is orthogonal to the imaginary straight lines.

12. The wind propulsion device (1) of any one of claims 1 to 3, wherein as viewed from an axial direction along the rotation axis (RC), those among the plurality of blades (10A to 10I) that are disposed closer to the center of the frame (21) each extend so that a length of the imaginary straight line is at least 1 / 2 a diameter of the frame (21).

13. The wind propulsion device of any one of claims 1 to 3, wherein each of the plurality of blades (10A to 10I) has a twisted shape such that a first imaginary straight line (FL1), which connects opposite ends of each of the plurality of blades (10A to 10I) at a first position on the rotation axis (RC), and a second imaginary straight line (FL2), which connects opposite ends of each of the plurality of blades (10A to 10I) at a second position on the rotation axis (RC) different from the first position, intersect with each other as viewed from an axial direction along the rotation axis (RC).

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