Electric vertical take-off and landing aircraft

Abstract

To increase a flight time or a payload for an electric vertical take-off and landing aircraft.SOLUTION: An eVTOL 1 comprises: an airframe 2; rotors 3A, 3B; motors 4A, 4B; a battery 21; a power generator 22; an engine 23 for driving the power generator 22; and a controller 26 which controls the engine 23 for power generation of the power generator 22, and controls charging from the power generator 22 to the battery 21 and power supply from the power generator 22 and the battery 21 to the motors 4A, 4B; and can perform vertical take-off and landing, levitation and horizontal displacement. The controller 26 controls the engine 23 so that maximum output power of the power generator 22 is smaller than levitation power that is supplied to the motors 4A, 4B during levitation, and is larger than horizontal displacement power that is supplied to the motors 4A, 4B during horizontal displacement.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The technology disclosed in this specification relates to an aircraft configured to be able to take off and land vertically, which is an electrically operated electric vertical take-off and landing aircraft.

Background Art

[0002] Conventionally, as this type of technology, for example, the technology described in Patent Document 1 below is known. This electric vertical take-off and landing aircraft includes a fuselage, a motor connected to be able to transmit power to a rotor, a battery that supplies power to the motor, a generator that generates power for charging the battery, an engine that operates with fuel to drive the generator, and a control device that controls the driving of the engine and the generator for charging the battery and determines whether the aircraft can wait for take-off and landing. The control device is configured to adjust the output of the engine so as to keep the amount of charge in the battery at a constant level at all times.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the electric vertical take-off and landing aircraft described in Patent Document 1, in order to keep the amount of charge from the generator to the battery constant at all times, if the power generation of the generator is always set to the maximum output, the generated power will be excessive for the entire flight. Here, most of the flight of the electric vertical take-off and landing aircraft is cruising flight, and the time for take-off and landing and hovering in the air is short. Therefore, if the power generation of the generator is always set to the maximum output in this way, the generated power of the generator will be excessive for the entire flight of the aircraft, and there is a concern of causing an excessive increase in size and weight of the generator. As a result, the amount of fuel that can be carried on the aircraft will decrease, and the flight time and payload of the aircraft will be reduced.

[0005] This disclosed technology has been made in view of the above circumstances, and its object is to provide an electric vertical takeoff and landing aircraft that enables an increase in flight time or payload.

Means for Solving the Problems

[0006] In an electric vertical takeoff and landing aircraft comprising a fuselage, a plurality of rotors, motors for driving each rotor, a rechargeable battery for supplying power to the motors, a generator for generating power, an engine that operates by fuel for driving the generator, and control means for controlling the engine for power generation by the generator and for controlling charging from the generator to the battery and supply of power from the generator and the battery to the motors, and configured to enable vertical takeoff and landing, hovering in the air, and horizontal movement of the fuselage, the control means is intended to control the engine such that the maximum power of the generated power of the generator is smaller than the hovering power supplied to the motors during hovering and larger than the horizontal movement power supplied to the motors during horizontal movement.

[0007] According to the configuration of the above technology, in an electric vertical takeoff and landing aircraft provided with a generator driven by an engine, the control means controls the engine such that the maximum power of the generated power of the generator is smaller than the hovering power and larger than the horizontal movement power. Thereby, during the entire flight, the generated power is optimized and does not become excessive. Therefore, when the physical size of the electric vertical takeoff and landing aircraft is kept constant, the engine can be miniaturized, and the battery can be enlarged or the amount of loaded fuel can be increased by the amount of its miniaturization, or the amount of load on the fuselage can be increased.

[0008] In order to achieve the above object, the technology according to claim 2 is intended to charge a part of the differential power between the generated power and the horizontal movement power from the generator to the battery when the generated power is larger than the horizontal movement power in the technology according to claim 1.

[0009] According to the configuration of the above technology, in addition to the operation of the technology described in claim 1, when the electric vertical takeoff and landing aircraft moves horizontally, a part of the differential power between the generated power exceeding the horizontal movement power is effectively charged from the generator to the battery.

[0010] To achieve the above object, the technology described in claim 3 is, in the technology described in claim 1 or 2, characterized in that the control means discharges a part of the differential power between the generated power and the horizontal movement power from the battery to the motor when the generated power is smaller than the horizontal movement power.

[0011] According to the configuration of the above technology, in addition to the operation of the technology described in claim 1 or 2, when the electric vertical takeoff and landing aircraft moves horizontally, a part of the differential power between the generated power insufficient for the horizontal movement power is effectively supplied from the battery to the motor.

[0012] To achieve the above object, the technology described in claim 4 is, in the technology described in claim 3, characterized in that the control means discharges power from the battery to the motor when the remaining charge of the battery is greater than a predetermined value.

[0013] According to the configuration of the above technology, in addition to the operation of the technology described in claim 3, when the remaining charge of the battery is greater than a predetermined value, power is supplied from the battery to the motor, so that the battery is not overcharged.

[0014] To achieve the above object, the technology described in claim 5 is, in the technology described in claim 3, characterized in that the control means determines the generated power based on the remaining amount of fuel, and discharges power from the battery to the motor when the remaining amount of fuel is smaller than a predetermined value.

[0015] According to the configuration of the above technology, in addition to the operation of the technology described in claim 3, when the remaining amount of fuel used in the engine is smaller than a predetermined value, power is supplied from the battery to the motor, so that the engine and the generator are not driven unreasonably.

Effect of the Invention

[0016] According to the technology described in claim 1, the flight time of the electric vertical takeoff and landing aircraft can be extended, or the payload of the electric vertical takeoff and landing aircraft can be increased.

[0017] According to the technology described in claim 2, in addition to the effect of the technology described in claim 1, the battery can be efficiently charged.

[0018] According to the technology described in claim 3, in addition to the effect of the technology described in claim 1 or 2, the motor can be stably driven, and stable horizontal movement can be performed.

[0019] According to the technology described in claim 4, in addition to the effect of the technology described in claim 3, damage caused by overcharging of the battery can be suppressed.

[0020] According to the technology described in claim 5, in addition to the effect of the technology described in claim 3, damage caused by unreasonable operation of the engine and generator can be suppressed.

Brief Description of the Drawings

[0021]

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Embodiment for Carrying Out the Invention

[0022] Hereinafter, a detailed description will be given with reference to the drawings of an embodiment in which an electric vertical takeoff and landing aircraft (hereinafter referred to as “eVTOL”) is embodied.

[0023] [Regarding the Mechanical Configuration of the eVTOL] FIG. 1 shows the appearance of the eVTOL 1 in a perspective view. As shown in FIG. 1, the eVTOL 1 includes a fuselage 2, two rotors 3A and 3B, and two motors 4A and 4B for driving each of the rotors 3A and 3B. The fuselage 2 includes a body 11, a main wing 12 horizontally disposed at the center of the body 11, a horizontal tail 13 horizontally disposed at the rear side of the body 11, and a pair of vertical tails 14 vertically disposed at both left and right ends of the horizontal tail 13. At both left and right ends of the main wing 12, tilt devices 5A and 5B are provided which house each of the motors 4A and 4B and support each of the rotors 3A and 3B.

[0024] Each of the tilt devices 5A and 5B incorporates a drive mechanism (not shown) and is provided so as to be rotatable in a direction perpendicular to the main wing 12. By rotating each of the tilt devices 5A and 5B with respect to the main wing 12, each of the rotors 3A and 3B is configured to be switchable between an upward position (see FIG. 1) and a forward position. This eVTOL 1 arranges each of the rotors 3A and 3B in the upward position by each of the tilt devices 5A and 5B when vertically taking off and landing or hovering in the air, and arranges each of the rotors 3A and 3B in the forward position by each of the tilt devices 5A and 5B when moving horizontally. That is, this eVTOL 1 switches each of the rotors 3A and 3B between the upward position and the forward position by each of the tilt devices 5A and 5B, and rotationally drives each of the rotors 3A and 3B by each of the motors 4A and 4B at those respective positions, thereby enabling the vertical takeoff and landing, hovering in the air, and horizontal movement of the fuselage 2.

[0025] [Regarding the Electrical Configuration of the eVTOL, etc.] Fig. 2 shows the electrical configuration of the eVTOL1 and the like in a block diagram. As shown in Fig. 2, the eVTOL1 includes a rechargeable battery 21 for supplying power to each motor 4A, 4B, a generator 22 for generating power, an engine 23 that operates on fuel (gasoline) to drive the generator 22, and a controller 26 and a power management circuit 27 that control the engine 23 to generate power from the generator 22 and control the charging from the generator 22 to the battery 21 and the supply of power from the generator 22 and the battery 21 to each motor 4A, 4B. The generator 22 and the engine 23 constitute a power generation unit 24. The controller 26 and the power management circuit 27 correspond to an example of the "control means" of this disclosed technology.

[0026] As shown in Fig. 2, gasoline is supplied to the engine 23 from a gasoline tank 16. The power generated by the generator 22 is charged into the battery 21 via the power management circuit 27 and can be supplied to each motor 4A, 4B and each tilt device 5A, 5B. Also, the power charged in the battery 21 can be supplied to each motor 4A, 4B and each tilt device 5A, 5B via the power management circuit 27. The controller 26 controls the operations of the engine 23, the power management circuit 27, and the battery 21 by control signals.

[0027] [Regarding the flight control of the eVTOL] Next, the flight control of the eVTOL1 will be described below. The controller 26 stores various control programs described below and controls the flight of the eVTOL1 based on those control programs.

[0028] Here, FIG. 3 graphically shows the relationships of the equivalent fuel consumption rate line EFCL, the equivalent output line EOL, the engine full throttle performance line WOT, the equivalent voltage line IL, and the operation line OL with respect to the engine speed and the current (generated current) of the generator 22 during the flight of the eVTOL1. In FIG. 3, the equivalent fuel consumption rate line EFCL is shown by a dashed line, the equivalent output line EOL is shown by a solid line, the engine full throttle performance line WOT is shown by a thick double-dashed line, the equivalent voltage line IL is shown by a broken line, and the operation line OL is shown by a thick solid line. The operation line OL is set to be orthogonal to the equivalent fuel consumption rate line EFCL. The voltage increases from the left side A1 to the right side A2 of the array of the plurality of equivalent voltage lines IL. The output increases from the lower side B1 to the upper side B2 of the array of the plurality of equivalent output lines EOL. The fuel consumption rate increases from the middle side C1 to the outer side C2 of the array of the plurality of equivalent fuel consumption rate lines EFCL.

[0029] In this embodiment, it is charged when the flight power of the eVTOL1 < the generated power (output operating point P2), and discharged when the flight power > the generated power (fuel consumption operating point P1). When transitioning from the fuel consumption operating point P1 to the charging idle operating point P5, the generator current and the engine speed are controlled by the controller 26 so as to transiently move above the operation line OL, and the output of the engine 23 is set to transition on the operation line OL. In FIG. 3, the eVTOL1 normally operates the generator 22 at the fuel consumption operating point P1 on the operation line OL where the fuel consumption of the engine 23 is optimal (low output mode), operates the generator 22 at the output operating point P2 on the operation line OL when the charge state drops or an extremely large flight power is required (high output mode), operates the generator 22 at the intermediate operating point P3 on the operation line OL between the fuel consumption operating point P1 and the output operating point P2 when avoiding overheating of the battery 21, operates the generator 22 at the no-load idle operating point P4 on the operation line OL when not generating power at the generator 22 in the idle state (no-load idle mode), and operates the generator 22 at the generating idle operating point P5 on the operation line OL when generating power at the generator 22 in the idle state (idle mode for charging). Also, regardless of that, the output of the generator 22 is changed according to the flight power.

[0030] The generated power of the generator 22 is, in FIG. 3, for example, "1500 W" at the fuel consumption operating point P1, "3000 W" at the output operating point P2, "0 W" at the no-load idle operating point P4, and "500 W" at the charging idle operating point P5.

[0031] In the eVTOL 1 of this embodiment, as a factor of overheating of the rechargeable battery 21, the influence of Joule heat due to internal resistance is mainly considered. In order to avoid overheating of the battery 21, it is preferable to make the current due to charging and discharging of the battery 21 zero as much as possible. The power required for the flight of the eVTOL 1 changes due to disturbances such as the motion state and attitude of the airframe 2 and wind. By changing the output of the generator 22 in accordance with the flight power required for this flight, the current related to the charging and discharging of the battery 21 can be made zero as much as possible, and overheating of the battery 21 can be suppressed.

[0032] In FIGS. 4 to 9, for the eVTOL 1, changes in various parameters with respect to time after the start of flight under certain conditions are shown in graphs. FIG. 4 shows an example of changes in the generated power GP, the battery power BP, and the flight power FP with respect to time after the start of flight in a graph. In FIG. 4, the portion surrounded by the dashed-dotted circle is enlarged and shown above. FIG. 5 shows an example of changes in the state of charge (SOC) with respect to time after the start of flight in a graph. FIG. 6 shows an example of changes in the remaining amount of gasoline with respect to time after the start of flight in a graph. FIG. 7 shows an example of changes in the flight altitude with respect to time after the start of flight in a graph. FIG. 8 shows an example of changes in the horizontal flight distance with respect to time after the start of flight in a graph. FIG. 9 shows an example of changes in the horizontal flight speed with respect to time after the start of flight in a graph.

[0033] As shown in Fig. 4, immediately after starting at time t0, the flight power FP is in the vicinity of the hovering power LP near the maximum power in order to vertically lift off the aircraft 2 and keep it hovering in the air. After that, it decreases as the transition to horizontal movement occurs. During the horizontal movement between time t1 and time t2, it becomes constant at a predetermined horizontal movement power HMP. Between time t2 and time t3, in order to keep the aircraft 2 hovering in the air and perform a vertical landing, it increases again to the vicinity of the hovering power LP. Also, the generated power GP periodically changes between the maximum power GPmax and the minimum power GPmin between time t0 and time t3. Also, the battery power BP is in the vicinity of the maximum power immediately after starting at time t0. After that, in accordance with the change in the generated power GP, it periodically changes between the minimum power BPmin and the maximum power BPmax between time t1 and time t2. Between time t2 and time t3, in accordance with the hovering and vertical landing of the aircraft 2, it increases again to the vicinity of the maximum power.

[0034] With the power control of the eVTOL1 shown in Fig. 4, the state of charge SOC, as shown in Fig. 5, periodically increases and decreases within a certain range value (for example, 0.7 to about 0.9) between time t0 and time t3. The gasoline remaining amount, as shown in Fig. 6, gradually decreases from full between time t0 and time t3. Also, the flight altitude, as shown in Fig. 7, rapidly increases immediately after time t0 and remains constant until it rapidly decreases immediately before time t3. The horizontal flight distance, as shown in Fig. 8, gradually increases from 0 between time t0 and time t3. The horizontal flight speed, as shown in Fig. 9, rapidly increases immediately after time t0 and remains constant until it rapidly decreases immediately before time t3.

[0035] Here, as a premise for the flight control of the eVTOL1, as shown in Fig. 4, the controller 26 controls the engine 23 so that the maximum power GPmax of the generated power GP of the generator 22 is smaller than the hovering power LP supplied to each motor 4A, 4B during hovering and larger than the horizontal movement power HMP supplied to each motor 4A, 4B during horizontal movement.

[0036] [Regarding the content of flight control] Next, the details of flight control will be described. FIG. 10 shows, in a flowchart, one of the control programs executed by the controller 26, which is a main routine regarding the details of flight control.

[0037] In this main routine, at step 100, the controller 26 executes "pre-takeoff operations". A subroutine regarding the control of this pre-takeoff operation is shown in a flowchart in FIG. 11.

[0038] When the process transfers to this subroutine, at step 101, the controller 26 checks the remaining battery level. That is, the controller 26 checks the remaining charge of the battery based on the voltage of the battery 21.

[0039] Next, at step 102, the controller 26 determines whether the remaining battery level allows for takeoff. If the determination result is affirmative, the controller 26 transfers the process to step 103; if the determination result is negative, the controller 26 transfers the process to step 106.

[0040] At step 103, the controller 26 controls the generator 22 to a predetermined no-load idle mode (refer to P4 in FIG. 3). For this purpose, the controller 26 controls the output of the engine 23.

[0041] Next, at step 104, it is determined whether there is a user takeoff request. This user takeoff request can be input to the controller 26 via a communication device (not shown and not described) for example. If the determination result is affirmative, the controller 26 transfers the process to step 105; if the determination result is negative, the controller 26 returns the process to step 101.

[0042] At step 105, the controller 26 controls the aircraft 2 to the multicopter mode. That is, the controller 26 controls each tilt device 5A, 5B and each motor 4A, 4B to switch each rotor 3A, 3B to the upward position and start the rotation of each rotor 3A, 3B.

[0043] On the other hand, when shifting from step 102 and reaching step 106, after the controller 26 controls the generator 22 by the engine 23 to a predetermined charging idle mode (see P5 in FIG. 3), the process returns to step 101.

[0044] The above "pre - takeoff operation" is an operation for taking off after charging the battery 21 to a certain extent because excessive reduction of the battery remaining amount due to discharge will lead to deterioration of the battery 21.

[0045] Next, in the main routine, at step 110, the controller 26 determines whether takeoff has been determined. The controller 26 can make a takeoff determination based on, for example, the measured value of an altimeter (not shown and not described). If the determination result is affirmative, the process proceeds to step 120; if the determination result is negative, the process returns to step 100.

[0046] At step 120, the controller 26 executes the "takeoff operation". A sub - routine regarding the control of this takeoff operation is shown in FIG. 12 as a flowchart.

[0047] When the process shifts to this sub - routine, at step 121, the controller 26 controls the generator 22 to a high - output mode. To do so, the controller 26 controls the output of the engine 23.

[0048] Next, at step 122, the controller 26 controls the battery 21 to a discharge mode.

[0049] Next, in the main routine, at step 130, the controller 26 determines whether the aircraft 2 has reached the target altitude. The controller 26 can make this determination based on, for example, the measured value of the altimeter. If the determination result is affirmative, the process proceeds to step 140; if the determination result is negative, the process returns to step 120.

[0050] In step 140, the controller 26 executes a "fixed-wing mode transition operation" to shift the aircraft 2 to horizontal movement. A subroutine related to the control of this fixed-wing mode transition operation is shown in FIG. 13 as a flowchart.

[0051] When the process transfers to this subroutine, in step 141, the controller 26 changes the angle of the rotor rotation axes (the rotation axes of the respective rotors 3A, 3B). In this case, the respective rotors 3A, 3B are switched to the forward-facing positions. For this purpose, the controller 26 rotates the respective tilt devices 5A, 5B.

[0052] Next, in step 142, the controller 26 controls the generator 22 in the high-output mode. For this purpose, the controller 26 controls the output of the engine 23.

[0053] Next, in step 143, the controller 26 controls the battery 21 in the discharge mode.

[0054] Next, in step 144, the controller 26 determines whether the rotor rotation axes are horizontal. That is, the controller 26 determines whether the respective rotors 3A, 3B have switched to the forward-facing positions. The controller 26 can make this determination based on, for example, the measured values of a level gauge (not shown and not described). If this determination result is affirmative, the process transfers to step 150, and if this determination result is negative, the process returns to 141.

[0055] In the above "fixed-wing mode transition operation", until the respective rotors 3A, 3B reach the forward-facing positions, the respective tilt devices 5A, 5B are controlled so that the angles of the rotation axes of the respective rotors 3A, 3B change little by little.

[0056] Next, in step 150 of the main routine, the controller 26 executes an "operation in fixed-wing state". That is, the aircraft 2 is horizontally moved. A subroutine related to the control of this operation in fixed-wing state is shown in FIG. 14 as a flowchart.

[0057] When the process transfers to this subroutine, the controller 26 checks the remaining battery level at step 301.

[0058] Next, at step 302, the controller 26 determines whether the battery 21 is within the target remaining battery level range in the fixed-wing mode. If the determination result by the controller 26 is affirmative, the process transfers to step 303, and if the determination result is negative, the process transfers to step 312.

[0059] At step 303, the controller 26 maintains the current output mode of the generator 22. To do so, the controller 26 maintains the current output of the engine 23.

[0060] Next, at step 304, the controller 26 maintains the current charge / discharge state of the battery 21. That is, neither charging nor discharging is performed on the battery 21.

[0061] Next, at step 305, the controller 26 checks the remaining gasoline level in the gasoline tank 16. The controller 26 can make this determination based on, for example, the measured value of a gasoline gauge (not shown and not described) provided in the gasoline tank 16.

[0062] Next, at step 306, the controller 26 determines whether there is remaining gasoline. If the determination result by the controller 26 is affirmative, the process transfers to step 307, and if the determination result is negative, the process transfers to step 317.

[0063] At step 307, the controller 26 checks whether the aircraft 2 has reached its destination. The controller 26 can perform this check based on, for example, the data of a "GPS" (not shown and not described).

[0064] Next, in step 308, the controller 26 determines whether the aircraft 2 has arrived at the destination. If the determination result is affirmative, the controller 26 transfers the process to step 309, and if the determination result is negative, the controller 26 returns the process to step 301.

[0065] In step 309, the controller 26 checks the remaining battery level.

[0066] Next, in step 310, the controller 26 determines whether there is a remaining battery level sufficient for landing. If the determination result is affirmative, the controller 26 transfers the process to step 311, and if the determination result is negative, the controller 26 transfers the process to step 318.

[0067] In step 311, the controller 26 permits the start of the multicopter mode transition and transfers the process to step 160.

[0068] On the other hand, when transferring from step 302 and in step 312, the controller 26 determines whether the remaining battery level is equal to or lower than the lower limit value. If the determination result is affirmative, the controller 26 transfers the process to step 313, and if the determination result is negative, the controller 26 transfers the process to step 315.

[0069] In step 313, the controller 26 controls the generator 22 to the high-output mode. For this purpose, the controller 26 controls the output of the engine 23.

[0070] Next, in step 314, the controller 26 controls the battery 21 to the charging mode and transfers the process to step 305.

[0071] In steps 312 to 314 described above, when the generated power GP of the generator 22 is greater than the horizontal movement power HMP, the controller 26 charges a part of the differential power between the generated power GP and the horizontal movement power HMP from the generator 22 to the battery 21.

[0072] On the one hand, when transitioning from step 312 to step 315, the controller 26 controls the generator 22 in a low-output mode. To do so, the controller 26 controls the output of the engine 23.

[0073] Next, at step 316, the controller 26 controls the battery 21 in a discharge mode and transfers the process to step 305.

[0074] In steps 312, 315, and 316 above, when the generated power GP of the generator 22 is smaller than the horizontal movement power HMP, the controller 26 discharges a part of the differential power between the generated power GP and the horizontal movement power HMP from the battery 21 to each of the motors 4A and 4B.

[0075] In steps 312 to 316 above, basically, the controller 26 repeatedly makes the aircraft 2 cruise in the high-output mode and the low-output mode of the generator 22 so that the remaining battery level stays within a predetermined range.

[0076] On the one hand, when transitioning from step 306 to step 317, the controller 26 performs an emergency determination and transfers the process to step 160.

[0077] On the one hand, when transitioning from step 310 to step 318, the controller 26 makes a fixed wing turn in the vicinity.

[0078] Next, at step 319, the controller 26 controls the generator 22 in a high-output mode. To do so, the controller 26 controls the output of the engine 23.

[0079] Next, at step 320, the controller 26 controls the battery 21 in a charging mode and returns the process to step 309.

[0080] When the aircraft 2 lands, if the remaining battery capacity that allows landing cannot be ensured, the battery 21 will deteriorate due to over-discharge. If the remaining battery capacity that allows landing can be ensured, the deterioration of the battery 21 due to over-discharge can be suppressed. Therefore, in the above steps 309 to 311 and steps 318 to 320, until the remaining battery capacity that allows landing can be ensured, the aircraft 2 is rotated in the vicinity by the main wing 12, and the generator 22 is operated to generate electricity at a high output to charge the battery 21.

[0081] And in the above steps 309 to 311, when the remaining charge of the battery 21 is greater than a predetermined value, the controller 26 discharges power from the battery 21 to each motor 4A, 4B.

[0082] Next, in the main routine, at step 160, the controller 26 determines whether there is no emergency determination. If this determination result is affirmative, the process proceeds to step 170, and if this determination result is negative, the process proceeds to step 210.

[0083] At step 170, the controller 26 executes a "normal multi-copter mode transition operation" to horizontally move the aircraft 2. A subroutine related to the control of this normal multi-copter mode transition operation is shown in FIG. 15 as a flowchart.

[0084] When the process transfers to this subroutine, at step 171, the controller 26 changes the angle of the rotor rotation axis. That is, the controller 26 changes each rotor 3A, 3B to the forward position. For this purpose, the controller 26 rotates each tilt device 5A, 5B.

[0085] Next, at step 172, the controller 26 controls the generator 22 to the high-output mode. For this purpose, the controller 26 controls the output of the engine 23.

[0086] Next, at step 173, the controller 26 controls the battery 21 to the discharge mode.

[0087] Next, in step 174, the controller 26 determines whether the rotor rotation axis is vertical. That is, the controller 26 determines whether each of the rotors 3A and 3B has switched to the upward position. If the determination result by the controller 26 is affirmative, the process proceeds to step 175. If the determination result is negative, the process returns to step 171.

[0088] In step 175, the controller 26 completes the multicopter mode transition and proceeds the process to step 180.

[0089] In step 180 of the main routine, the controller 26 executes a "normal landing operation" to land the aircraft 2. A subroutine related to the control of this normal landing operation is shown in a flowchart in FIG. 16.

[0090] When the process proceeds to this subroutine, in step 181, the controller 26 controls the generator 22 to the high-output mode. For this purpose, the controller 26 controls the output of the engine 23.

[0091] Next, in step 182, the controller 26 controls the battery 21 to the discharge mode.

[0092] Next, in step 190 of the main routine, the controller 26 determines whether the landing of the aircraft 2 has been determined. The controller 26 can make this determination based on, for example, the measured value of an altimeter (not shown and not described). If the determination result by the controller 26 is affirmative, the process proceeds to step 200. If the determination result is negative, the process returns to step 180.

[0093] Then, in step 200, the controller 26 controls the generator 22 to the no-load idle mode (see P4 in FIG. 3) and ends the subsequent process. For this purpose, the controller 26 controls the output of the engine 23.

[0094] On the other hand, when transitioning from step 160 and reaching step 210, the controller 26 executes an "emergency multi-copter mode transition operation". A subroutine regarding the control of this emergency multi-copter mode transition operation is shown in the flowchart of FIG. 17.

[0095] When the process transfers to this subroutine, at step 211, the controller 26 changes the angle of the rotor rotation axis. That is, the controller 26 switches each rotor 3A, 3B to the upward position. For this purpose, the controller 26 rotates each tilt device 5A, 5B.

[0096] Next, at step 212, the controller 26 controls the battery 21 to the discharge mode.

[0097] Next, at step 213, the controller 26 determines whether the rotor rotation axis is vertical. That is, the controller 26 determines whether each rotor 3A, 3B has switched to the upward position. If the determination result is affirmative, the controller 26 transfers the process to step 214; if the determination result is negative, the controller 26 returns the process to step 211.

[0098] At step 214, the controller 26 completes the multi-copter mode transition and transfers the process to step 220.

[0099] In the above steps 150, 160, and 210, the controller 26 determines the generated power GP of the generator 22 based on the gasoline remaining amount, determines it as an emergency when the gasoline remaining amount is less than a predetermined value, and causes the battery 21 to supply power to each motor 4A, 4B.

[0100] In the above steps 150, 160, and 210, when the remaining gasoline amount runs out during the flight of the aircraft 2, for example, when the headwind becomes stronger than expected and it takes longer to reach the destination than planned, the controller 26 determines it as an emergency and is configured to perform an emergency landing. That is, before the remaining battery amount runs out and the aircraft 2 crashes, the aircraft 2 is landed on the spot in multicopter mode. During an emergency landing, since there is a risk that the battery 21 may be over-discharged, it can also be configured to notify the user to that effect.

[0101] In step 220 of the main routine, the controller 26 controls the battery 21 to the discharge mode.

[0102] Next, in step 230, the controller 26 determines whether landing has been determined. If this determination result is affirmative, the controller 26 transfers the process to step 240, and if this determination result is negative, the controller 26 returns the process to step 220.

[0103] In step 240, the controller 26 notifies the user to replace the battery 21. For example, the controller 26 performs this notification by lighting an alarm (not shown and not described). Then, the controller 26 ends the subsequent process.

[0104] Here, FIG. 18 shows the changes in (A) the power generation state, (B) the generated power of the generator 22, and (C) the remaining gasoline amount during normal flight by a time chart. FIG. 19 shows the changes in (A) the power generation state, (B) the generated power of the generator 22, and (C) the remaining gasoline amount during flight including emergencies by a time chart.

[0105] As shown in FIG. 18, during normal flight, from time t0 to time t2, in order to perform vertical takeoff and fixed-wing transition, the state of charge of the battery 21 is below the available takeoff / landing remaining amount L2 (for example, "85%") and decreases once until it falls below the fixed-wing target remaining amount lower limit L3 (for example, "80%"). Thereafter, during fixed-wing flight from time t2 to time t4, the state of charge increases and decreases between the fixed-wing target remaining amount upper limit L1 (for example, "90%") and the target remaining amount lower limit L3. Then, from time t4 to time t6, in order to perform multicopter transition and vertical landing, the state of charge decreases below the available takeoff / landing remaining amount L2 to a predetermined remaining amount that is below the fixed-wing target remaining amount lower limit L3. In this case, the gasoline remaining amount becomes zero when landing is completed.

[0106] As shown in FIG. 19, when the gasoline remaining amount runs out at time t5 during fixed-wing flight different from normal flight, and during emergency flight when the state of charge of the battery 21 falls below the fixed-wing target remaining amount lower limit L3, from time t5 to time t6, in order to perform multicopter transition and vertical landing, the charging power of the battery 21 will be used.

[0107] [Regarding the operation and effect of eVTOL] According to the configuration of the eVTOL 1 of this embodiment described above, in the eVTOL 1 equipped with the generator 22 driven by the engine 23, the controller 26 controls the engine 23 so that the maximum power GPmax of the generated power GP of the generator 22 is smaller than the hovering power LP in the air and larger than the horizontal movement power HMP. As a result, throughout the flight of the eVTOL 1, the generated power GP of the generator 22 is optimized and does not become excessive. Therefore, when the size of the eVTOL 1 is kept constant, the engine 23 can be miniaturized, and accordingly, the battery 21 can be enlarged or the amount of loaded gasoline can be increased, or the amount of luggage loaded on the airframe 2 can be increased. For this reason, the flight time of the eVTOL 1 can be extended, or the payload of the eVTOL 1 can be increased. That is, it becomes possible to fly the eVTOL 1 to the destination without running out of battery. Also, the generator 22 can be lightened, and the payload and the amount of gasoline loaded can be increased accordingly.

[0108] Figure 20 shows, by a graph, the relationship between each component of the eVTOL1 of the present embodiment and the weight breakdown. Figure 21 shows, by a graph, the relationship between each component of a conventional proportional eVTOL and the weight breakdown. As shown in Figures 20 and 21, the present embodiment and the proportional example have common components, namely, a fuselage, an engine, a generator, a suspension structure, an electrical circuit, a tank, gasoline, and a battery. Between the present embodiment and the proportional example, the weights of the fuselage, the generator, the suspension structure, the circuit, the tank, and the whole are the same. In contrast, in this embodiment, the weight of the engine can be reduced from "5.0 (kg)" to "2.0 (kg)", whereby the weight of the battery can be increased from "1.9 (kg)" to "4.1 (kg)", and the gasoline can be increased from "0.1 (kg)" to "0.9 (kg)". In this case, the flight time of the eVTOL1 could be extended due to the increase in the size of the battery and the increase in gasoline.

[0109] According to the configuration of this embodiment, when the eVTOL1 is horizontally moving, a part of the differential power between the generated power GP exceeding the horizontal movement power HMP is effectively charged from the generator 22 to the battery 21. Therefore, the battery 21 can be efficiently charged.

[0110] According to the configuration of this embodiment, when the eVTOL1 is horizontally moving, a part of the differential power between the generated power insufficient for the horizontal movement power HMP is effectively supplied from the battery 21 to each of the motors 4A and 4B. Therefore, each of the motors 4A and 4B can be stably driven, and stable horizontal movement can be performed.

[0111] According to the configuration of this embodiment, when the remaining charge amount of the battery 21 is greater than a predetermined value, power is supplied from the battery 21 to each of the motors 4A and 4B, so that the battery 21 is not overcharged. Therefore, damage or the like due to overcharging of the battery 21 can be suppressed.

[0112] According to the configuration of this embodiment, when the remaining amount of gasoline used in the engine 23 is less than a predetermined value, power is supplied from the battery 21 to each of the motors 4A and 4B, so that the engine 23 and the generator 22 are not forced to drive. Therefore, damage and the like caused by the forced operation of the engine 23 and the generator 22 can be suppressed.

[0113] <Another embodiment> Note that the disclosed technology is not limited to the above-described embodiment, and a part of the configuration can be appropriately changed without departing from the spirit of the disclosed technology and implemented as follows.

[0114] In the above embodiment, the eVTOL 1 is configured to enable vertical takeoff and landing, hovering in the air, and horizontal movement by providing a fixed wing and switching the left and right rotors 3A and 3B between the forward position and the upward position by the left and right tilt devices 5A and 5B. On the other hand, it is also possible to configure an eVTOL that enables vertical takeoff and landing, hovering in the air, and horizontal movement by using a multicopter configured to drive and control three or more upward rotors without a fixed wing.

Industrial applicability

[0115] This disclosed technology can be used in fields such as aerial photography surveying, material delivery, disaster investigation, monitoring, and rescue activities.

Explanation of reference numerals

[0116] 1 eVTOL 2 Airframe 3A Rotor 3B Rotor 4A Motor 4B Motor 21 Battery 22 Generator 23 Engine 26 Controller (control means) 27 Power management circuit (control means) GP Generated power GPmax Maximum power BP Battery power BPmax Maximum power FP Flight power LP Levitation power HMP Horizontal movement power

Claims

1. An airframe, a plurality of rotors, a motor for driving each of the rotors, a rechargeable battery for supplying power to the motor, a generator for generating the power, an engine that operates on fuel to drive the generator, and control means for controlling the engine for power generation by the generator and for controlling charging from the generator to the battery and power supply from the generator and the battery to the motor. In an electric vertical takeoff and landing aircraft configured to enable vertical takeoff and landing, hovering in the air, and horizontal movement of the airframe, the control means controls the engine such that the maximum power of the generated power of the generator is smaller than the hovering power supplied to the motor during hovering and larger than the horizontal movement power supplied to the motor during horizontal movement. An electric vertical takeoff and landing aircraft characterized by the above.

2. In the electric vertical takeoff and landing aircraft according to Claim 1, when the generated power is larger than the horizontal movement power, the control means charges a part of the differential power between the generated power and the horizontal movement power from the generator to the battery. An electric vertical takeoff and landing aircraft characterized by the above.

3. In the electric vertical takeoff and landing aircraft according to Claim 1 or 2, when the generated power is smaller than the horizontal movement power, the control means discharges a part of the differential power between the generated power and the horizontal movement power from the battery to the motor. An electric vertical takeoff and landing aircraft characterized by the above.

4. In the electric vertical takeoff and landing aircraft according to Claim 3, when the remaining charge of the battery is larger than a predetermined value, the control means discharges power from the battery to the motor. An electric vertical takeoff and landing aircraft characterized by the above.

5. In the electric vertical takeoff and landing aircraft according to Claim 3, the control means determines the generated power based on the remaining amount of fuel, and when the remaining amount of fuel is smaller than a predetermined value, discharges power from the battery to the motor. An electric vertical takeoff and landing aircraft characterized by the above.

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