Control device for electric aircraft and control method for electric aircraft

Abstract

A control device (6) controls an electric aircraft (100) comprising a motor (2) that drives a rotor blade (1), a storage battery (3) that supplies electric power to the motor (2), an electricity generator (4) that uses an internal combustion engine (5) as a motive power source and that can supply electric power to the motor (2) and the storage battery (3), and an altitude acquiring device (7) that acquires a flight altitude. The control device (6): causes the electric aircraft (100) to take off by supplying electric power from the storage battery (3) to the motor (2) while keeping the internal combustion engine (5) stopped; after the electric aircraft (100) has taken off, determines whether an altitude (H) of the electric aircraft (100) is at least equal to an altitude threshold (Ht); and activates the internal combustion engine (5) if the altitude (H) of the electric aircraft (100) acquired by the altitude acquiring device (7) is at least equal to the altitude threshold (Ht).

Description

Control device for electric aircraft and control method for electric aircraft

[0001] The present invention relates to a control device for an electric aircraft and a control method for an electric aircraft.

[0002] To extend flight time, electric aircraft have been developed that are equipped with a generator powered by an internal combustion engine in addition to a battery. Patent Document 1 discloses a system for controlling the internal combustion engine (gas turbine internal combustion engine) of such electric aircraft to cause the generator to generate electricity based on the amount of electricity stored in the battery.

[0003] Japanese Patent Application Laid-Open No. 2019-077361

[0004] In the control system for an electric aircraft described in Patent Document 1, not only is the internal combustion engine at maximum output to cause the generator to generate electricity during takeoff, but the propeller is driven using electricity stored in a battery, making it possible to downsize the internal combustion engine (gas turbine internal combustion engine). However, noise and exhaust gases are generated from the internal combustion engine during takeoff, posing a problem for use in urban areas or places close to residential environments.

[0005] An object of the present invention is to provide a control device for an electric aircraft that can suppress noise and exhaust gases generated from an internal combustion engine during takeoff.

[0006] The present application includes multiple means for solving the above-mentioned problems, and one example is a control device for controlling an electric aircraft that includes a motor that drives a rotor, a storage battery that supplies power to the motor, a generator that uses an internal combustion engine as a power source and can supply power to the motor and the storage battery, and an altitude acquisition device that acquires flight altitude, wherein the control device supplies power from the storage battery to the motor while the internal combustion engine is stopped to cause the electric aircraft to take off, and after the electric aircraft takes off, determines whether the altitude of the electric aircraft acquired by the altitude acquisition device is equal to or greater than an altitude threshold, and starts the internal combustion engine if the altitude of the electric aircraft is equal to or greater than the altitude threshold.

[0007] According to the present invention, noise and exhaust gases generated from the internal combustion engine during takeoff can be suppressed, making it possible to use the aircraft in urban areas and places close to residential areas. Problems, configurations, and effects other than those described above will become clear from the description of the following embodiments.

[0008] 1 is a schematic configuration diagram of an electric aircraft according to a first embodiment of the present invention. FIG. 1 is a block diagram showing an example of the hardware configuration of a control device according to the first embodiment of the present invention, a device for inputting data to the control device, and a device for outputting command data from the control device. FIG. 2 is a block diagram showing an example of a flowchart executed by the control device according to the first embodiment of the present invention at takeoff. FIG. 3 is a block diagram showing an example of a flowchart executed by the control device according to the first embodiment of the present invention at landing. FIG. 3 is a schematic configuration diagram of an electric aircraft according to a second embodiment of the present invention. FIG. 4 is a block diagram showing an example of the hardware configuration of a control device according to the second embodiment of the present invention, a device for inputting data to the control device, and a device for outputting command data from the control device. FIG. 4 is a graph showing the remaining battery charge of a charger and the altitude of the electric aircraft when the electric aircraft is taken off and ascended based only on the remaining battery charge. FIG. 5 is a graph showing the relationship between the coolant temperature of an internal combustion engine and the combustion variation rate at startup. FIG. 6 is a graph showing the relationship between the ambient air temperature of the electric aircraft and the combustion variation rate at startup. FIG. 7 is a graph showing the relationship between the ambient air pressure of the electric aircraft and the combustion variation rate at startup. FIG. 8 is a diagram showing an example of a flowchart executed by the control device according to the second embodiment of the present invention at takeoff. FIG. 9 is a diagram showing an example of a flowchart executed by the control device according to the second embodiment of the present invention at landing. FIG. 10 is a graph showing the relationship between the fuel temperature of an internal combustion engine and the combustion variation rate at startup. 1 is a graph showing the relationship between the humidity around an electric aircraft and the fuel temperature threshold of an internal combustion engine. FIG. 2 is a graph showing the relationship between the ethanol content in fuel and the fuel temperature threshold. FIG. 3 is an example of a time chart showing the state of an electric aircraft from takeoff to landing at a destination according to a second embodiment of the present invention. FIG. 4 is a schematic configuration diagram of an electric aircraft according to a third embodiment of the present invention. FIG. 5 is a block diagram showing an example of the hardware configuration of a control device according to a third embodiment of the present invention, a device that inputs data to the control device, and a device that outputs command data from the control device. FIG. 6 is a diagram showing an example of a flowchart executed at takeoff by the control device according to the third embodiment of the present invention.

[0009] The configurations and operations of control devices for electric aircraft according to first to third embodiments of the present invention will be described below with reference to the drawings. Note that the same reference numerals in each drawing indicate the same parts.

[0010] First Embodiment FIG. 1 is a schematic diagram of an electric aircraft according to a first embodiment of the present invention.

[0011] The electric aircraft 100 of this embodiment is, for example, an electric vertical take-off and landing aircraft (eVTOL), and includes a rotor 1, a motor 2, a storage battery 3, a generator 4, an internal combustion engine 5, a control device 6, and an altitude acquisition device 7.

[0012] The rotors 1 are devices that generate lift for the electric aircraft 100. The electric aircraft 100 of this embodiment is provided with four rotors 1.

[0013] The motors 2 are devices that drive the rotors 1. In the electric aircraft 100 of this embodiment, four motors 2 are mechanically connected to the four rotors 1, respectively.

[0014] The storage battery 3 is a device that supplies power to the motor 2 via a power converter, and preferably has a capacity greater than or equal to the output required for the electric aircraft 100 to take off.

[0015] The generator 4 is a device that uses an internal combustion engine 5 as a power source and can supply electric power to the motor 2 and the storage battery 3 via a power converter.

[0016] The internal combustion engine 5 is a device that is mechanically connected to the generator 4 to drive the generator 4 to generate electricity, such as a reciprocating engine, and can use gasoline, diesel, gas, etc. as fuel.

[0017] The control device 6 is a powertrain control device that controls the powertrain (power transmission system), and supplies power from the storage battery 3 to the motor 2 while the internal combustion engine 5 is stopped to cause the electric aircraft 100 to take off. After the electric aircraft 100 has taken off, the control device 6 determines whether the altitude H of the electric aircraft 200 acquired by the altitude acquisition device 7 is equal to or greater than an altitude threshold Ht, and starts the internal combustion engine 5 if the altitude H of the electric aircraft 200 is equal to or greater than the altitude threshold Ht. The altitude threshold Ht is the minimum altitude (e.g., 500 feet (approximately 152 meters)) that must be maintained above urban areas as specified by guidelines, etc.

[0018] The altitude acquisition device 7 is a device that acquires the flight altitude of the electric aircraft 100, and specifically, for example, is a barometric altitude sensor that detects altitude using pressure or a radio wave altitude sensor that detects altitude using radio waves. Since the altitude acquisition device 7 is a device that can acquire the flight altitude of the electric aircraft 100, for example, a device that calculates the altitude of the electric aircraft 200 based on positioning signals received from multiple positioning satellites, such as a GPS (Global Positioning System) receiver, may also be used. The control device 6 determines whether the altitude H of the electric aircraft 200 acquired by the altitude acquisition device 7 is equal to or greater than an altitude threshold Ht. The control device 6 may also determine whether the electric aircraft 100 has taken off based on the altitude H of the electric aircraft 200 acquired by the altitude acquisition device 7. An altimeter (barometric altimeter or radio altimeter) may also be used for the altitude acquisition device 7. In this case, an operator, instead of the control device 6, may determine whether the altitude H of the electric aircraft 200 is equal to or greater than the altitude threshold Ht or whether the electric aircraft 100 has taken off, based on the measurement value of the altimeter.

[0019] 2 is a block diagram showing an example of the hardware configuration of the control device 6 according to this embodiment, a device that inputs data to the control device 6, and a device that outputs command data from the control device 6. The control device 6 is configured by an electronic computer.

[0020] As shown in FIG. 2, the control device 6 includes an input / output circuit 6a, a first storage device 6b, a computing device 6c, and a second storage device 6d.

[0021] The input / output circuit 6a is a device that receives signals and data from the outside and transmits internal information and results to the outside. The altitude H of the electric aircraft 100 acquired by the altitude acquisition device 7 is input to the input / output circuit 6a. The data of the altitude H of the electric aircraft 100 input to the input / output circuit 6a is sent to and stored in the first storage device 6b.

[0022] The first storage device 6b is a device that temporarily stores data, such as a random access memory (RAM). The data on the altitude H of the electric aircraft 100 that is temporarily stored in the first storage device 6b is read by the calculation device 6c.

[0023] The arithmetic device 6c is a device, such as a CPU (Central Processing Unit), that calculates whether to start the internal combustion engine 5 based on altitude data of the electric aircraft 100. The arithmetic device 6c reads a program and the altitude threshold Ht from the second storage device 6d, calculates whether to start the internal combustion engine 5 based on the data of the altitude H of the electric aircraft 100 input from the first storage device 6b, and outputs command data for the storage battery 3 and the internal combustion engine 5.

[0024] The second storage device 6d is a device, such as a ROM (Read-Only Memory), that stores the program and the altitude threshold Ht. The program and the altitude threshold Ht are stored in advance in the second storage device 6d.

[0025] Command data for the controlled objects (storage battery 3 and internal combustion engine 5) calculated by the calculation device 6c according to the control program is stored in the first memory device 6b and then sent to the controlled objects (storage battery 3 and internal combustion engine 5) via the input / output circuit 6a.

[0026] Fig. 3 is a diagram showing an example of a flowchart executed by the control device 6 according to this embodiment at the time of takeoff. Fig. 4 is a diagram showing an example of a flowchart executed by the control device 6 according to this embodiment at the time of landing.

[0027] The control device 6 controls the start and stop of the internal combustion engine 5 based on data of the altitude H acquired by the altitude acquisition device 7. Specifically, the control device 6 executes the process shown in Fig. 3 at the time of takeoff, and executes the process shown in Fig. 4 at the time of landing.

[0028] 3 is initiated when the operator starts operation of the electric aircraft 100, and in takeoff step 1, the control device 6 supplies power from the storage battery 3 to the motor 2 to drive the rotor 1. The control device 6 also maintains the internal combustion engine 5 in a stopped state.

[0029] Next, the control device 6 determines whether the electric aircraft 100 has taken off in takeoff step 2. Note that the altitude H acquired by the altitude acquisition device 7, for example, can be used to determine whether the electric aircraft 100 has taken off.

[0030] If it is determined that the electric aircraft 100 has taken off (YES), the process proceeds to takeoff step 3. If it is determined that the electric aircraft 100 has not taken off (NO), the process returns to takeoff step 1.

[0031] Next, in takeoff step 3, the control device 6 determines whether the altitude H of the electric aircraft 100 is equal to or greater than the altitude threshold Ht. As described above, the altitude threshold Ht is the minimum altitude (e.g., 500 feet (approximately 152 meters)) that must be maintained above urban areas as specified by guidelines, etc. The altitude H acquired by the altitude acquisition device 7 is used to determine whether the electric aircraft 100 is equal to or greater than the altitude threshold Ht.

[0032] If the altitude H of the electric aircraft 100 is less than the altitude threshold Ht (NO), the process returns to takeoff step 3. If the altitude H of the electric aircraft 100 is equal to or greater than the altitude threshold Ht (YES), in takeoff step 4, the control device 6 starts the internal combustion engine 5 and ends the takeoff processing.

[0033] Next, when the electric aircraft 100 approaches the destination, the control device 6 executes the landing process shown in FIG. 4 .

[0034] First, when the operator starts landing the electric aircraft 100, the flow executed by the control device 6 during landing in Fig. 4 is initiated, and in landing step 1, the control device 6 determines whether the altitude H of the electric aircraft 100 acquired by the altitude acquisition device 7 is less than the altitude threshold Ht. If the altitude H is equal to or greater than the altitude threshold Ht (NO), the process returns to landing step 1. If the altitude H is less than the altitude threshold Ht (YES), the process proceeds to landing step 2, where the control device 6 stops the internal combustion engine 5, and the process proceeds to landing step 3.

[0035] Next, in landing step 3, the control device 6 drives the motor 2 using only the power supplied from the storage battery 3 to land the electric aircraft 100, and then ends the landing process.

[0036] [Effect] The control device 6 of this embodiment causes the electric aircraft 100 to take off by supplying power from the storage battery 3 to the motor 2 while keeping the internal combustion engine 5 stopped, and after the electric aircraft 100 takes off, determines whether the altitude of the electric aircraft 100 acquired by the altitude acquisition device 7 is equal to or greater than the altitude threshold Ht, and if the altitude H of the electric aircraft 100 is equal to or greater than the altitude threshold Ht, starts the internal combustion engine 5. Therefore, the electric aircraft 100 of this embodiment stops the internal combustion engine 5 after takeoff until the altitude H becomes equal to or greater than the altitude threshold Ht, making it possible to suppress noise and exhaust gases generated by the internal combustion engine 5, and therefore can take off from urban areas and locations close to residential areas.

[0037] Furthermore, when approaching a destination and landing, the control device 6 of this embodiment preferably stops the internal combustion engine 5 when the altitude H of the electric aircraft 100 acquired by the altitude acquisition device 7 falls below the altitude threshold Ht, and lands the electric aircraft 100 by driving the motor 2 using only the power supplied from the storage battery 3. As a result, the electric aircraft 100 of this embodiment stops the internal combustion engine 5 until the altitude threshold Ht is passed and landing is performed, thereby suppressing the noise and exhaust gas generated by the internal combustion engine 5, and therefore can land in urban areas or places close to residential areas.

[0038] Furthermore, the control device 6 may determine that the electric aircraft 100 has taken off based on the altitude H of the electric aircraft 100 acquired by the altitude acquisition device 7. This makes it possible to easily determine that the electric aircraft 100 has taken off. Furthermore, because an altimeter (pressure altimeter or radio altimeter) that measures the altitude of the aircraft is usually attached to an aircraft, this can be used as the altitude acquisition device 7 to acquire the altitude H of the electric aircraft 200, and it can be determined whether the altitude H is equal to or greater than the altitude threshold Ht or whether the electric aircraft 100 has taken off, thereby reducing costs.

[0039] Furthermore, the control method for controlling the electric aircraft 100 of this embodiment is characterized in that the electric aircraft 100 takes off by supplying power from the storage battery 3 to the motor 2 while the internal combustion engine 5 is stopped, and after the electric aircraft 100 takes off, it is determined whether the altitude H of the electric aircraft 100 acquired by the altitude acquisition device 7 is equal to or greater than an altitude threshold Ht, and if the altitude H of the electric aircraft 100 is equal to or greater than the altitude threshold Ht, the internal combustion engine 5 is started. Therefore, the control method for controlling the electric aircraft 100 of this embodiment stops the internal combustion engine 5 after takeoff until the altitude H becomes equal to or greater than the altitude threshold Ht, making it possible to suppress noise and exhaust gases generated by the internal combustion engine 5, and therefore allowing the electric aircraft to take off from urban areas or locations close to residential areas.

[0040] 5 is a schematic diagram of an electric aircraft 200 according to a second embodiment of the present invention. The electric aircraft 200 according to this embodiment differs from the electric aircraft 100 according to the first embodiment in that it includes a battery remaining capacity sensor 203, a water temperature sensor 205, an environmental sensor 208, a position receiver 209 having the function of the altitude acquisition device 7, a start-up confirmation sensor 210, and a start-up auxiliary device 211.

[0041] The battery remaining capacity sensor 203 is one of a plurality of start condition sensors that detect the start condition of the internal combustion engine 5 , and detects the remaining battery capacity of the storage battery 3 .

[0042] The water temperature sensor 205 is one of a plurality of start condition sensors that detect the start conditions of the internal combustion engine 5, and detects the temperature of the cooling water for the internal combustion engine 5.

[0043] The environmental sensor 208 is a sensor that detects physical quantities such as the temperature and air pressure around the electric aircraft 100. In this embodiment, the environmental sensor 208 is provided, but instead of the environmental sensor 208, an air temperature sensor that detects the temperature around the electric aircraft 100, an air pressure sensor that detects the air pressure around the electric aircraft 100, and a humidity sensor that detects the humidity around the electric aircraft 100 may be provided.

[0044] The position receiver 9 is a device that calculates the position and altitude of the electric aircraft 200 based on positioning signals received from multiple positioning satellites, such as a GPS (Global Positioning System) receiver, and detects, for example, the distance D between the electric aircraft 100 and an urban area and the altitude H of the electric aircraft 200. Therefore, the position receiver 9 has the function of the altitude acquisition device 7.

[0045] The start confirmation sensor 210 is a sensor that confirms the start of the internal combustion engine 5, and is, for example, a crank angle sensor.

[0046] The starting assistance device 211 is a device that assists in starting the internal combustion engine 5, and has at least one of the following functions: increasing the amount of fuel injected into the engine and increasing the fuel concentration of the fuel-air mixture mixed in the engine; and increasing the ignition energy, which is the energy required for ignition by the spark plug.

[0047] FIG. 6 is a block diagram showing an example of the hardware configuration of the control device 206 according to this embodiment, a device that inputs data to the control device 206, and a device that outputs command data from the control device 206.

[0048] The control device 206 according to this embodiment differs from the control device 6 according to the first embodiment in the following respects. Specifically, the devices that input data to the control device 206 are a battery remaining capacity sensor 203, a water temperature sensor 205, an environmental sensor 208, a position receiver 209 having the function of the altitude acquisition device 7, and a start-up confirmation sensor 210. Also, in addition to the altitude threshold Ht, other thresholds described below are stored in the second storage device 206d. Also, a start-up auxiliary device 211 is added to the devices to which command data is output from the control device 206. As described above, the environmental sensor 8 may be replaced with an air temperature sensor that detects the air temperature around the electric aircraft 100, an air pressure sensor that detects the air pressure around the electric aircraft 100, or a humidity sensor that detects the humidity around the electric aircraft 100.

[0049] Specifically, the data input from the battery remaining amount sensor 203 to the control device 206 is the remaining battery amount (SOC: State of Charge) of the storage battery 3. Furthermore, the data input from the water temperature sensor 205 to the control device 206 is the coolant temperature Tw of the internal combustion engine 5.

[0050] The data input from the environmental sensor 208 to the control device 206 is physical quantities around the electric aircraft 100, such as the temperature Ta and the air pressure Pa. The temperature Ta may be a value detected by an air temperature sensor, and the air pressure Pa may be a value detected by an air pressure sensor. As described above, the data input from the position receiver 209 to the control device 206 is, for example, the distance D between the electric aircraft 200 and the urban area and the altitude H of the electric aircraft 200.

[0051] In addition, the second memory device 206d stores, for example, a takeoff SOCt, which is the remaining battery charge required in the storage battery 3 when the electric aircraft 200 takes off, a water temperature threshold Twt, which is the threshold for the coolant temperature Tw of the internal combustion engine 5, and an air temperature threshold Tat and an air pressure threshold Pat, which are thresholds for the air temperature Ta and air pressure Pa around the electric aircraft 100, respectively.

[0052] FIG. 7 is a graph showing the remaining battery capacity SOC of the storage battery 3 and the altitude H of the electric aircraft 200 when the electric aircraft 200 takes off and ascends based only on the remaining battery capacity SOC.

[0053] As shown in FIG. 7, the takeoff SOCt is the remaining battery charge SOC required for the electric aircraft 200 to take off and ascend to an altitude threshold Ht, which is the minimum altitude that must be maintained above an urban area.

[0054] Fig. 8 is a graph showing the relationship between the coolant temperature Tw of the internal combustion engine 5 and the rate of variation of combustion at startup. Fig. 9 is a graph showing the relationship between the ambient temperature Ta of the electric aircraft 200 according to this embodiment and the rate of variation of combustion at startup. Fig. 10 is a graph showing the relationship between the ambient air pressure Pa of the electric aircraft 200 according to this embodiment and the rate of variation of combustion at startup.

[0055] The startup combustion fluctuation rate is an index that represents the degree of instability and fluctuation in combustion that occurs when the internal combustion engine 5 is started. The higher the startup combustion fluctuation rate, the more difficult it is to start the internal combustion engine 5, and the lower the startup combustion fluctuation rate, the easier it is to start the internal combustion engine 5.

[0056] As shown in FIG. 8 , the water temperature threshold Twt is the coolant temperature Tw of the internal combustion engine 5 when the rate of variation in combustion at startup reaches the start limit value of the internal combustion engine 5. Since the rate of variation in combustion at startup is smaller as the coolant temperature Tw of the internal combustion engine 5 is higher, the higher the coolant temperature Tw, the easier it is to start the internal combustion engine 5. On the other hand, as the coolant temperature Tw decreases, the rate of variation in combustion at startup increases, making it more difficult to start the internal combustion engine 5. On the other hand, as the temperature of the electric aircraft 200 rises, the coolant temperature Tw decreases. Therefore, it is preferable that the control device 6 start the internal combustion engine 5 while the temperature of the electric aircraft 200 rises and the coolant temperature Tw decreases, and the coolant temperature Tw becomes equal to or lower than the water temperature threshold Twt, causing the internal combustion engine 5 to reach its start limit.

[0057] 9 , the temperature threshold Tat is the ambient temperature Ta of the electric aircraft 200 when the starting combustion variation rate reaches the starting limit of the internal combustion engine 5. The higher the ambient temperature Ta of the electric aircraft 200, the smaller the starting combustion variation rate, and therefore the higher the temperature Ta, the easier it is to start the internal combustion engine 5. On the other hand, as the temperature Ta decreases, the starting combustion variation rate increases, making it more difficult to start the internal combustion engine 5. On the other hand, as the electric aircraft 200 rises, the temperature Ta decreases. Therefore, it is preferable that the control device 6 start the internal combustion engine 5 while the electric aircraft 200 rises and the temperature Ta decreases, and the temperature Ta becomes equal to or lower than the temperature threshold Tat, causing the internal combustion engine 5 to reach its starting limit.

[0058] 10 , the atmospheric pressure threshold Pat is the atmospheric pressure Pa around the electric aircraft 200 when the combustion variation rate at startup reaches the startup limit of the internal combustion engine 5. The higher the atmospheric pressure Pa around the electric aircraft 200, the smaller the combustion variation rate at startup, and therefore the higher the atmospheric pressure Pa, the easier it is to start the internal combustion engine 5. On the other hand, as the atmospheric pressure Pa decreases, the combustion variation rate at startup increases, making it more difficult to start the internal combustion engine 5. On the other hand, as the electric aircraft 200 ascends, the atmospheric pressure Pa decreases. Therefore, it is preferable that the control device 6 start the internal combustion engine 5 while the electric aircraft 200 ascends and the atmospheric pressure Pa decreases, and the atmospheric pressure Pa becomes equal to or less than the atmospheric pressure threshold Pat, causing the internal combustion engine 5 to reach its startup limit.

[0059] Fig. 11 is a diagram showing an example of a flowchart executed by the control device 206 according to this embodiment at takeoff. Fig. 12 is a diagram showing an example of a flowchart executed by the control device 206 according to this embodiment at landing.

[0060] The flow executed by the control device 206 at takeoff according to this embodiment differs from the flow executed by the control device 6 at takeoff according to the first embodiment in the following points.

[0061] First, it has a step of comparing the remaining battery charge SOC of the storage battery 3, the air temperature Ta and air pressure Pa detected by the environmental sensor 208, the coolant temperature Tw of the internal combustion engine 5, and the distance D from the urban area detected by the position receiver 209 with their respective threshold values.

[0062] Secondly, the method includes a step of checking whether the internal combustion engine 5 has started, and if it has not started, starting the internal combustion engine 5 using the starting aid device 211 .

[0063] In this embodiment, the position receiver 209 acquires the altitude H instead of the altitude acquisition device 7 that acquires the flight altitude. The air temperature Ta may be detected by an air temperature sensor that detects the air temperature around the electric aircraft 200, and the air pressure Pa may be detected by an air pressure sensor that detects the air pressure around the electric aircraft 200.

[0064] Furthermore, the flow executed by the control device 206 according to this embodiment at the time of landing differs from the flow executed by the control device 6 according to the first embodiment at the time of landing in that it includes the following two steps.

[0065] One is a landing step 201 in which the remaining battery capacity SOC of the storage battery 3 is compared with a landing SOCt, which is the remaining battery capacity SOC required for the electric aircraft 200 to descend and land from an altitude threshold Ht, which is the minimum altitude that the electric aircraft 200 must maintain above urban areas.

[0066] The other is a landing step 203 in which the distance D from the city detected by the position receiver 209 is compared with a distance threshold Dt.

[0067] Specifically, the control device 206 executes the processes shown in FIGS.

[0068] First, when the operator starts operation of the electric aircraft 200, the flow executed by the control device 206 at takeoff in Fig. 11 is started, and in a takeoff step 201, the control device 206 determines whether the remaining battery capacity SOC is equal to or greater than the takeoff SOCt based on the detected value of the remaining battery capacity SOC of the storage battery 3 by the remaining battery capacity sensor 203. Note that the takeoff SOCt is the remaining battery capacity SOC required for the electric aircraft 200 to take off and climb and reach an altitude of the altitude threshold Ht, as described above.

[0069] If the remaining battery charge SOC is equal to or greater than the takeoff SOCt (YES), in a takeoff step 202, power is supplied from the storage battery 3 to the motor 2 to drive the rotor 1. If the remaining battery charge SOC is less than the takeoff SOCt (NO), the control device 206 does not supply power from the storage battery 3 to the motor 2, turns off the power supply of the electric aircraft 200, and ends the flow, in order to charge the storage battery 3 from a power source (for example, a ground commercial power source).

[0070] Next, the control device 206 determines whether or not the electric aircraft 200 has taken off in a takeoff step 203. Whether or not the electric aircraft 200 has taken off can be determined based on the altitude H acquired by the position receiver 209.

[0071] If it is determined that the electric aircraft 200 has taken off (YES), the process proceeds to a takeoff step 204. If it is determined that the electric aircraft 200 has not taken off (NO), the process returns to the takeoff step 201.

[0072] Next, in the takeoff step 204, the control device 206 determines whether the remaining battery charge SOC is equal to or lower than the lower threshold Lt, the coolant temperature Tw is equal to or lower than the water temperature threshold Twt, the air temperature Ta is equal to or lower than the air temperature threshold Tat, and the air pressure Pa is equal to or lower than the air pressure threshold Pat. The lower threshold Lt is the minimum charge amount required for the storage battery 3.

[0073] If the battery remaining charge SOC is equal to or lower than the lower limit threshold Lt, the coolant temperature Tw is equal to or lower than the water temperature threshold Twt, the air temperature Ta is equal to or lower than the air temperature threshold Tat, or the air pressure Pa is equal to or lower than the air pressure threshold Pat (YES), there is a risk that the internal combustion engine 5 will not start, so the control device 206 sends command data to start the internal combustion engine 5 in the takeoff step 205 and proceeds to the takeoff step 206.

[0074] If the battery remaining charge SOC is not equal to or lower than the lower limit threshold Lt, the coolant temperature Tw is not equal to or lower than the water temperature threshold Twt, the air temperature Ta is not equal to or lower than the air temperature threshold Tat, or the air pressure Pa is not equal to or lower than the air pressure threshold Pat (NO), the process proceeds to takeoff step 207.

[0075] In the above example, the control device 206 makes a determination in the takeoff step 204 based on the remaining battery charge SOC of the storage battery 3, the coolant temperature Tw of the internal combustion engine 5, and the ambient temperature Ta and atmospheric pressure Pa of the electric aircraft 200. However, the present invention is not limited to these examples.

[0076] For example, the control device 206 may determine whether the humidity detected by the environmental sensor 208 or the humidity sensor is equal to or greater than a humidity threshold value. This is because, when the humidity around the electric aircraft 200 becomes high, it becomes difficult to start the internal combustion engine 5 for the following reason.

[0077] First, an appropriate air-fuel ratio (ratio of air to fuel) is required for proper combustion in the internal combustion engine 5. However, when humidity is high, the oxygen concentration in the air decreases, and more air is required to burn the same amount of fuel. Therefore, when humidity is high, there is a risk that insufficient air will be supplied, making it difficult to start the internal combustion engine 5.

[0078] Second, in high humidity conditions, moisture can affect the engine's spark plugs, wiring, etc. Moisture on the spark plugs can make ignition difficult or unreliable, which can make it difficult to start the internal combustion engine 5.

[0079] Third, high humidity can hinder fuel evaporation. If the fuel is supplied to the combustion chamber as a liquid rather than evaporating into a mist, a uniform air-fuel mixture cannot be obtained, which can cause combustion problems and make it difficult to start the internal combustion engine 5.

[0080] Furthermore, in the case of rainy weather, the humidity is high, so weather may be added to the conditions for determining whether to perform the takeoff step 204 .

[0081] FIG. 13 is a graph showing the relationship between the fuel temperature Tf of the internal combustion engine 5 and the combustion variation rate at startup.

[0082] A fuel temperature sensor that detects the fuel temperature Tf of the internal combustion engine 5 may be used as one of the multiple start condition sensors that detect the start conditions of the internal combustion engine 5. In the takeoff step 204, the control device 206 may determine whether the fuel temperature Tf detected by the fuel temperature sensor is equal to or lower than a fuel temperature threshold value Tft shown in FIG.

[0083] The fuel temperature threshold value Tft is the fuel temperature Tf of the internal combustion engine 5 when the combustion variation rate at startup reaches the startup limit value of the internal combustion engine 5, as shown in FIG.

[0084] The reason why it is determined in the takeoff step 204 whether the fuel temperature Tf detected by the fuel temperature sensor is equal to or lower than the fuel temperature threshold value Tft is that if the fuel temperature Tf of the internal combustion engine 5 becomes low, the vaporizability of the fuel will decrease, and the fuel will be supplied to the combustion chamber as a liquid without vaporizing, preventing an appropriate mixture from being obtained, making ignition and combustion difficult, and there is a risk that it will be difficult to start the internal combustion engine 5.

[0085] Fig. 14 is a graph showing the relationship between the humidity around the electric aircraft 200 and the fuel temperature threshold Tft of the internal combustion engine 5. As described above, when the humidity is high, the oxygen concentration in the air decreases and fuel evaporation is hindered, making it difficult to start the internal combustion engine 5. Therefore, the higher the humidity around the electric aircraft 200, the more difficult it becomes to start the internal combustion engine 5, and so as shown in Fig. 14, the fuel temperature threshold Tft may be set higher as the humidity around the electric aircraft 200 increases.

[0086] Furthermore, it is preferable to vary the fuel temperature threshold Tft depending on the type of fuel. For example, when comparing gasoline and bioethanol, bioethanol is more difficult to vaporize and therefore has a poorer starting time for the internal combustion engine 5. Therefore, it is preferable to set the fuel temperature threshold Tft for bioethanol higher than for gasoline.

[0087] 15 is a graph showing the relationship between the ethanol content in fuel and the fuel temperature threshold Tft. The higher the ethanol content in the fuel for the internal combustion engine 5, the more difficult it is to vaporize, resulting in poor starting of the internal combustion engine 5. Therefore, as shown in FIG. 15, the fuel temperature threshold Tft may be set higher as the ethanol content in the fuel increases.

[0088] 11 , in a takeoff step 207, the control device 6 determines whether the distance D between the electric aircraft 200 and the urban area, acquired by the position receiver 209, is equal to or greater than a distance threshold Dt. If the distance D is equal to or greater than the distance threshold Dt (YES), the electric aircraft 200 is away from urban areas and residential areas, and even if the internal combustion engine 5 generates noise and exhaust gas, the impact on people can be suppressed. Therefore, the control device 6 proceeds to a takeoff step 205, transmits command data to start the internal combustion engine 5, and proceeds to a takeoff step 206.

[0089] If the distance D is less than the distance threshold Dt (NO), the control device 206 determines in the takeoff step 208 whether the altitude H of the electric aircraft 200 acquired by the position receiver 209 is equal to or greater than the altitude threshold Ht.

[0090] If the altitude H of the electric aircraft 200 is less than the altitude threshold Ht (NO), the process returns to the takeoff step 204. If the altitude H of the electric aircraft 200 is equal to or greater than the altitude threshold Ht (YES), the process transmits command data to start the internal combustion engine 5 in the takeoff step 205, and the process proceeds to the takeoff step 206.

[0091] Next, the control device 206 determines whether or not the internal combustion engine 5 has started in a takeoff step 206. Whether or not the internal combustion engine 5 has started can be determined based on a detection value detected by the start confirmation sensor 210.

[0092] If it is determined that the internal combustion engine 5 has started (YES), the control device 206 ends the takeoff processing. If it is determined that the internal combustion engine 5 has not started (NO), the control device 206 proceeds to a takeoff step 209.

[0093] Next, in the takeoff step 209, the control device 206 attempts to start the internal combustion engine 5 by using the starting aid device 211, for example, by increasing the amount of fuel injected into the engine to increase the fuel concentration of the fuel-air mixture mixed in the engine, or by increasing the ignition energy, which is the energy required for ignition by the spark plug, and then returns to the takeoff step 206.

[0094] Next, the control device 206 determines again whether or not the internal combustion engine 5 has started in a takeoff step 206. If it is determined that the internal combustion engine 5 has started (YES), the control device 206 ends the takeoff processing, and if it is determined that the internal combustion engine 5 has not started (NO), the control device 206 attempts to start the internal combustion engine 5 again by the starting auxiliary device 211 in a takeoff step 209. Therefore, the control device 206 repeats the takeoff step 206 and the takeoff step 209 until the internal combustion engine 5 has started, and ends the takeoff processing when the internal combustion engine 5 has started.

[0095] Next, when the electric aircraft 200 approaches the destination, the control device 206 executes the landing process shown in FIG. 12 .

[0096] First, when the operator performs an operation to start landing of the electric aircraft 200, the flow executed by the control device 206 during landing shown in Fig. 12 is started, and in a landing step 201, the control device 206 determines whether the remaining battery capacity SOC of the storage battery 3 is equal to or greater than the landing SOCt based on the detected value of the remaining battery capacity SOC by the battery capacity sensor 203. The landing SOCt is the remaining battery capacity SOC required to stop the internal combustion engine 5 from the altitude threshold Ht and to descend and land the electric aircraft 200 using only power from the storage battery 3.

[0097] If the remaining battery capacity SOC is less than the landing SOCt (NO), the landing step 201 is executed from the beginning without stopping the internal combustion engine 5 in order to charge the storage battery 3 by the generator 4. If the remaining battery capacity SOC is equal to or greater than the landing SOCt (YES), the process proceeds to the landing step 202.

[0098] Next, in landing step 202, the control device 206 determines whether the altitude H of the electric aircraft 100 acquired by the position receiver 9 is less than the altitude threshold Ht. If the altitude H is equal to or greater than the altitude threshold Ht (NO), the internal combustion engine 5 is not stopped and the process returns to landing step 201. If the altitude H is less than the altitude threshold Ht (YES), the process proceeds to landing step 203.

[0099] Next, in landing step 203, the control device 206 determines whether the distance D between the electric aircraft 200 and the urban area, acquired by the position receiver 209, is less than the distance threshold Dt. If the distance D is equal to or greater than the distance threshold Dt (NO), the electric aircraft 200 is away from urban areas and residential environments, and even if the internal combustion engine 5 generates noise and exhaust gas, the impact on people can be suppressed, so the internal combustion engine 5 is not stopped and the process returns to landing step 201. If the distance D is less than the distance threshold Dt (YES), the process proceeds to landing step 204, where the internal combustion engine 5 is stopped, and the process proceeds to landing step 205.

[0100] Next, in a landing step 205, the control device 206 drives the rotor 1 using only the power of the storage battery 3, lands the electric aircraft 200, and ends the landing process.

[0101] FIG. 16 is an example of a time chart showing the state of the electric aircraft 200 according to this embodiment from takeoff to landing at the destination.

[0102] The vertical axis of Figure 16 shows the state of the electric aircraft 200, and from top to bottom are the altitude H of the electric aircraft 200, the coolant temperature Tw of the internal combustion engine 5, the air temperature Ta and air pressure Pa around the electric aircraft 200, the remaining battery charge SOC of the storage battery 3, and the output Gp of the generator 4.

[0103] The horizontal axis of FIG. 16, which is the time axis, is as follows.

[0104] Time 0 is the time when the electric aircraft 200 takes off.

[0105] Time t1 is the time when the internal combustion engine 5 is started. Note that in Fig. 16 , the internal combustion engine 5 is started because the coolant temperature Tw has reached the water temperature threshold value Twt, and the altitude H of the electric aircraft 200 has not yet reached the altitude threshold value Ht.

[0106] Time t2 is the time when the remaining battery charge SOC of the storage battery 3 reaches the upper limit threshold UL. The upper limit threshold UL is the maximum amount that can be charged to the storage battery 3.

[0107] Time t3 is the time when the altitude H of the electric aircraft 200 falls below the altitude threshold Ht and the internal combustion engine 5 is stopped.

[0108] Time t4 is the time when the electric aircraft 200 lands.

[0109] In Figure 16, the altitude threshold Ht is shown by dotted lines on the time chart for altitude H, the water temperature threshold Twt is shown by dotted lines on the time chart for coolant temperature Tw, the air temperature threshold Tat is shown by dotted lines on the time chart for air temperature Ta, the air pressure threshold Pat is shown by dotted lines on the time chart for air pressure Pa, and the upper limit threshold UL and lower limit threshold Lt are shown by dotted lines on the time chart for remaining battery charge SOC.

[0110] The control device 206 of this embodiment does not start the internal combustion engine 5 during takeoff, and drives the rotor 1 using only the power of the storage battery 3. Therefore, as shown in Fig. 16 , the remaining battery charge SOC decreases as the altitude H of the electric aircraft 200 increases. Furthermore, as the altitude H of the electric aircraft 200 increases, the coolant temperature Tw of the internal combustion engine 5, the atmospheric pressure Pa, and the temperature Ta around the electric aircraft 200 decrease.

[0111] Then, for example, when the coolant temperature Tw reaches a water temperature threshold Twt (time t1), which is the limit at which the internal combustion engine 5 can be started stably, if the coolant temperature Tw drops any further, the internal combustion engine 5 will no longer be able to start stably, and therefore the control device 206 starts the internal combustion engine 5 without waiting for the altitude H of the electric aircraft 200 to become equal to or higher than the altitude threshold Ht. After the internal combustion engine 5 is started, the coolant temperature Tw rises due to heat generated by the internal combustion engine 5.

[0112] Furthermore, after time t1, the control device 206 drives the internal combustion engine 5 so that the output Gp of the generator 4 exceeds the power consumed by the rotor 1 in order to increase the remaining battery charge SOC of the storage battery 3 .

[0113] Then, when the remaining battery charge SOC reaches the upper threshold UL and charging of the storage battery 3 is completed (time t2), the control device 206 drives the internal combustion engine 5 so that the output Gp of the generator 4 becomes the power consumed by the rotor 1.

[0114] Thereafter, as the electric aircraft 200 approaches the destination, the altitude H gradually decreases. Then, when the altitude H becomes less than the altitude threshold Ht (time t3), the control device 206 stops the internal combustion engine 5, drives the rotor 1 using only the power from the storage battery 3, and lands at the destination (time t4).

[0115] [Effect] The electric aircraft 200 of this embodiment further includes an environmental sensor 8 that detects physical quantities (e.g., temperature Ta, pressure Pa, and humidity) around the electric aircraft 200, and the control device 206 determines whether the physical quantities detected by the environmental sensor 8 have reached threshold values ​​for the physical quantities (e.g., temperature threshold Tat, pressure threshold Pat, and humidity threshold) (takeoff step 204), and if the physical quantities have reached the threshold values, it is preferable to start the internal combustion engine 5 and generate electricity with the generator 4. This makes it possible to prevent the internal combustion engine 5 from failing to start, which would make flight difficult, and allows the electric aircraft 200 to fly safely.

[0116] Note that the step of determining whether or not the physical quantity detected by the environmental sensor 8 has reached the threshold value of the physical quantity (takeoff step 204) is preferably executed after takeoff of the electric aircraft 200, and before the step of determining whether or not the distance D between the electric aircraft 200 and the urban area is equal to or greater than the distance threshold Dt (takeoff step 207) and the step of determining whether or not the altitude H of the electric aircraft 200 is equal to or greater than the altitude threshold Ht (takeoff step 208). As a result, even before the distance D between the electric aircraft 200 and the urban area reaches the distance threshold Dt or before the altitude of the electric aircraft 200 reaches the altitude threshold Ht, the internal combustion engine 5 starts when the physical quantity detected by the environmental sensor 8 has reached the threshold value of the physical quantity, thereby improving the flight safety of the electric aircraft 200.

[0117] Furthermore, the environmental sensor 208 in this embodiment is a temperature sensor that detects the temperature Ta around the electric aircraft 200, and the control device 206 determines whether the temperature Ta detected by the temperature sensor is equal to or lower than the temperature threshold Tat, and when the temperature Ta becomes equal to or lower than the temperature threshold Tat, it is preferable to start the internal combustion engine 5 and generate electricity with the generator 4. This makes it possible to prevent the internal combustion engine 5 from failing to start due to a drop in the temperature Ta around the electric aircraft 200, which would make flight difficult, and therefore allows the electric aircraft 200 to fly safely.

[0118] Note that the step of determining whether the temperature Ta detected by the temperature sensor has reached the temperature threshold value Tat (takeoff step 204) is preferably executed after takeoff of the electric aircraft 200, and before the step of determining whether the distance D between the electric aircraft 200 and the urban area is equal to or greater than the distance threshold value Dt (takeoff step 207) and the step of determining whether the altitude H of the electric aircraft 200 is equal to or greater than the altitude threshold value Ht (takeoff step 208). As a result, even before the distance D between the electric aircraft 200 and the urban area reaches the distance threshold value Dt or before the altitude of the electric aircraft 200 reaches the altitude threshold value Ht, the internal combustion engine 5 starts when the temperature Ta detected by the temperature sensor reaches the temperature threshold value Tat, thereby improving the flight safety of the electric aircraft 200.

[0119] Furthermore, the environmental sensor 208 in this embodiment is a barometric pressure sensor that detects the barometric pressure Pa around the electric aircraft 200, and the control device 206 determines whether the barometric pressure Pa detected by the barometric pressure sensor is equal to or lower than a barometric pressure threshold Pat, and if the barometric pressure Pa becomes equal to or lower than the barometric pressure threshold Pat, it is preferable to start the internal combustion engine 5 and generate electricity with the generator 4. This makes it possible to prevent the internal combustion engine 5 from failing to start due to a drop in the barometric pressure Pa around the electric aircraft 200, which would make flight difficult, and therefore allows the electric aircraft 200 to fly safely.

[0120] Note that the step of determining whether the atmospheric pressure Pa detected by the atmospheric pressure sensor has reached the atmospheric pressure threshold Pat (takeoff step 204) is preferably executed after takeoff of the electric aircraft 200, and before the step of determining whether the distance D between the electric aircraft 200 and the urban area is equal to or greater than the distance threshold Dt (takeoff step 207) and the step of determining whether the altitude H of the electric aircraft 200 is equal to or greater than the altitude threshold Ht (takeoff step 208). As a result, even before the distance D between the electric aircraft 200 and the urban area reaches the distance threshold Dt or before the altitude of the electric aircraft 200 reaches the altitude threshold Ht, the internal combustion engine 5 starts when the atmospheric pressure Pa detected by the atmospheric pressure sensor has reached the atmospheric pressure threshold Pat, thereby improving the flight safety of the electric aircraft 200.

[0121] Furthermore, the environmental sensor 208 in this embodiment is a humidity sensor that detects the humidity around the electric aircraft 200, and the control device 206 determines whether the humidity detected by the humidity sensor is equal to or greater than a humidity threshold, and when the humidity detected by the humidity sensor is equal to or greater than the humidity threshold, it is preferable to start the internal combustion engine 5 and generate electricity with the generator 4. This makes it possible to prevent the internal combustion engine 5 from failing to start due to an increase in the humidity around the electric aircraft 200, which would make flight difficult, and allows the electric aircraft 200 to fly safely.

[0122] Note that the step of determining whether the humidity detected by the humidity sensor has reached the humidity threshold (takeoff step 204) is preferably executed after takeoff of the electric aircraft 200, and before the step of determining whether the distance D between the electric aircraft 200 and the urban area is equal to or greater than the distance threshold Dt (takeoff step 207) and the step of determining whether the altitude H of the electric aircraft 200 is equal to or greater than the altitude threshold Ht (takeoff step 208). As a result, even before the distance D between the electric aircraft 200 and the urban area reaches the distance threshold Dt or before the altitude of the electric aircraft 200 reaches the altitude threshold Ht, the internal combustion engine 5 starts when the humidity detected by the humidity sensor has reached the humidity threshold, thereby improving the flight safety of the electric aircraft 200.

[0123] The electric aircraft 200 further includes a plurality of start-up condition sensors (e.g., a water temperature sensor 205 that detects the coolant temperature and a battery remaining capacity sensor 203 that detects the remaining battery capacity of the storage battery 3) that detect start-up conditions for the internal combustion engine 5, and the control device 206 determines whether a detection value detected by any of the plurality of start-up condition sensors has reached a threshold value, and if the detection value has reached the threshold value, it is preferable to start the internal combustion engine 5 and generate electricity with the generator 4. This makes it possible to prevent, for example, the internal combustion engine 5 from failing to start due to a drop in the coolant temperature Tw of the internal combustion engine 5, which would make flight difficult, or to prevent flight difficulty due to the storage battery 3 running out of battery power, thereby enabling the electric aircraft 200 to fly safely.

[0124] It is preferable that the step of determining whether a detection value detected by any of the plurality of activation condition sensors has reached a threshold value (takeoff step 204) be executed after takeoff of the electric aircraft 200, and before the step of determining whether a distance D between the electric aircraft 200 and an urban area is equal to or greater than a distance threshold value Dt (takeoff step 207) and the step of determining whether an altitude H of the electric aircraft 200 is equal to or greater than an altitude threshold value Ht (takeoff step 208). As a result, even before the distance D between the electric aircraft 200 and the urban area reaches the distance threshold value Dt or before the altitude of the electric aircraft 200 reaches the altitude threshold value Ht, the internal combustion engine 5 is started when a detection value detected by any of the plurality of activation condition sensors has reached a threshold value, thereby improving the flight safety of the electric aircraft 200.

[0125] Furthermore, in this embodiment, one of the multiple startup condition sensors that detect the startup condition of the internal combustion engine 5 is a water temperature sensor 205 that detects a coolant temperature Tw of the internal combustion engine 5, and the control device 206 preferably determines whether the coolant temperature Tw detected by the water temperature sensor 205 is equal to or higher than a water temperature threshold, and when the coolant temperature Tw is equal to or higher than the water temperature threshold, starts the internal combustion engine 5 and generates electricity with the generator 4. This makes it possible to prevent the internal combustion engine 5 from failing to start due to a drop in the coolant temperature Tw of the internal combustion engine 5, which would cause flight difficulties, and therefore allows the electric aircraft 200 to fly safely.

[0126] Note that the step of determining whether the coolant temperature Tw detected by the water temperature sensor 205 that detects the coolant temperature Tw of the internal combustion engine 5 has reached the water temperature threshold Twt (takeoff step 204) is preferably executed after takeoff of the electric aircraft 200 and before the step of determining whether the distance D between the electric aircraft 200 and the urban area is equal to or greater than the distance threshold Dt (takeoff step 207) and the step of determining whether the altitude H of the electric aircraft 200 is equal to or greater than the altitude threshold Ht (takeoff step 208). As a result, even before the distance D between the electric aircraft 200 and the urban area reaches the distance threshold Dt or before the altitude of the electric aircraft 200 reaches the altitude threshold Ht, the internal combustion engine 5 starts when the coolant temperature Tw detected by the water temperature sensor 205 that detects the coolant temperature Tw of the internal combustion engine 5 reaches the water temperature threshold Twt, thereby improving the flight safety of the electric aircraft 200.

[0127] Furthermore, in this embodiment, one of the multiple start condition sensors that detect the start condition of the internal combustion engine 5 is a battery remaining capacity sensor 203 that detects the remaining battery capacity SOC of the storage battery 3, and the control device 206 preferably determines whether the remaining battery capacity SOC detected by the battery remaining capacity sensor 203 has reached a lower limit threshold Lt, and if the remaining battery capacity SOC has reached the lower limit threshold Lt, starts the internal combustion engine 5 and generates electricity using the generator 4. In this way, the internal combustion engine 5 is started and power is supplied from the generator 4 to the motor 2 before the remaining battery capacity SOC of the storage battery 3 reaches the lower limit threshold Lt, thereby preventing flight difficulties and enabling the electric aircraft 200 to fly safely.

[0128] Note that the step of determining whether the remaining battery capacity SOC detected by the battery remaining capacity sensor 203 that detects the remaining battery capacity SOC of the storage battery 3 has reached a lower threshold value Lt (takeoff step 204) is preferably executed after takeoff of the electric aircraft 200 and before the step of determining whether the distance D between the electric aircraft 200 and the urban area is equal to or greater than a distance threshold value Dt (takeoff step 207) and the step of determining whether the altitude H of the electric aircraft 200 is equal to or greater than an altitude threshold value Ht (takeoff step 208). As a result, even before the distance D between the electric aircraft 200 and the urban area reaches the distance threshold value Dt or before the altitude of the electric aircraft 200 reaches the altitude threshold value Ht, the internal combustion engine 5 starts when the remaining battery capacity SOC detected by the battery remaining capacity sensor 203 that detects the remaining battery capacity SOC of the storage battery 3 reaches the lower threshold value Lt, thereby improving the flight safety of the electric aircraft 200.

[0129] Furthermore, in this embodiment, one of the multiple startup condition sensors that detect the startup condition of the internal combustion engine 5 is a fuel temperature sensor that detects the fuel temperature Tf of the internal combustion engine 5, and it is preferable to determine whether the fuel temperature Tf detected by the fuel temperature sensor is equal to or lower than a fuel temperature threshold Tft, and if the fuel temperature Tf becomes equal to or lower than the fuel temperature threshold Tft, to start the internal combustion engine 5 and generate electricity with the generator 4. This makes it possible to prevent the internal combustion engine 5 from failing to start due to a drop in the fuel temperature Tf of the internal combustion engine 5, which would cause flight difficulties, and therefore allows the electric aircraft 200 to fly safely.

[0130] Note that the step of determining whether the fuel temperature Tf detected by the fuel temperature sensor has reached the fuel temperature threshold Tft (takeoff step 204) is preferably executed after takeoff of the electric aircraft 200, and before the step of determining whether the distance D between the electric aircraft 200 and the urban area is equal to or greater than the distance threshold Dt (takeoff step 207) and the step of determining whether the altitude H of the electric aircraft 200 is equal to or greater than the altitude threshold Ht (takeoff step 208). As a result, even before the distance D between the electric aircraft 200 and the urban area reaches the distance threshold Dt or before the altitude of the electric aircraft 200 reaches the altitude threshold Ht, the internal combustion engine 5 starts when the fuel temperature Tf detected by the fuel temperature sensor has reached the fuel temperature threshold Tft, thereby improving the flight safety of the electric aircraft 200.

[0131] Furthermore, it is preferable that the fuel temperature threshold Tft increases as the humidity around the electric aircraft increases and as the ethanol content in the fuel for the internal combustion engine 5 increases. This further prevents the internal combustion engine 5 from failing to start and making flight difficult, allowing the electric aircraft 200 to fly safely.

[0132] Furthermore, the control device 206 of this embodiment preferably does not supply power from the storage battery 3 to the motor 2 when the remaining battery charge SOC detected by the remaining battery charge sensor 203 before takeoff of the electric aircraft 200 is less than a takeoff SOCt, which is the remaining battery charge required for takeoff. This makes it possible to prevent the internal combustion engine 5 from having to be started due to a lack of the remaining battery charge SOC at the time of takeoff of the electric aircraft 200 or before the altitude of the electric aircraft 200 reaches the altitude threshold Ht, thereby making it possible to suppress noise and exhaust gas emissions from the internal combustion engine in urban areas or places close to residential environments.

[0133] Furthermore, the electric aircraft 200 of this embodiment further includes a position receiver 209, and the control device 206 determines whether the distance D between the electric aircraft 200 and an urban area obtained by the position receiver 209 is equal to or greater than a distance threshold Dt, and if the distance D is equal to or greater than the distance threshold Dt, it is preferable to start the internal combustion engine 5 and generate electricity with the generator 4. This allows the internal combustion engine 5 to start in a location away from urban areas and human living environments, thereby reducing the impact of noise and exhaust gas on people.

[0134] In addition, the step of determining whether the distance D between the electric aircraft 200 and the urban area obtained by the position receiver 209 is greater than or equal to the distance threshold Dt (takeoff step 207) is preferably performed after the takeoff of the electric aircraft 200, after the step of determining whether the physical quantity detected by the environmental sensor 208 has reached a physical quantity threshold, or whether the detection value detected by any of the multiple start-up condition sensors of the internal combustion engine 5 has reached a threshold (takeoff step 204).

[0135] This prevents the internal combustion engine 5 from being unable to start when the distance D between the electric aircraft 200 and the urban area detected by the position receiver 209 becomes equal to or greater than the distance threshold Dt and an attempt is made to start the internal combustion engine 5, thereby improving the safety of the flight of the electric aircraft 200.

[0136] Furthermore, the step of determining whether the distance D between the electric aircraft 200 and the urban area, acquired by the position receiver 209, is equal to or greater than a distance threshold Dt (takeoff step 207) is preferably executed before the step of determining whether the altitude H of the electric aircraft 200 is equal to or greater than an altitude threshold Ht (takeoff step 208). This allows the internal combustion engine 5 to be started earlier, enabling the electric aircraft 200 to fly safely.

[0137] The electric aircraft 200 further includes a start confirmation sensor 210 that confirms the start of the internal combustion engine 5, and a start assist device 211 that assists in the start of the internal combustion engine, and the control device 206 determines whether or not the internal combustion engine 5 is to be started based on the detection value of the start confirmation sensor 210, and if the internal combustion engine 5 is not started, starts the internal combustion engine 5 using the start assist device 211 and generates electricity with the generator 4. This makes it possible to prevent the internal combustion engine 5 from being unable to start, thereby improving the flight safety of the electric aircraft 200.

[0138] (Third embodiment) Figure 17 is a schematic configuration diagram of an electric aircraft 300 according to a third embodiment of the present invention. Figure 18 is a block diagram showing an example of the hardware configuration of a control device 306 according to a third embodiment of the present invention, a device for inputting data to the control device 306, and a device for outputting command data from the control device 306. Figure 19 is a diagram showing an example of a flowchart executed at takeoff by the control device according to the third embodiment.

[0139] The electric aircraft 300 according to this embodiment differs from the electric aircraft 200 according to the second embodiment in that it includes an exhaust catalyst 305, which is a catalyst provided in the exhaust pipe of the internal combustion engine 5, and a catalyst temperature sensor 312 that detects the temperature of the exhaust catalyst 305. Note that although the start confirmation sensor 210 and the start assist device 211 are not included in Fig. 17, the electric aircraft 300 may also include the start confirmation sensor 210 and the start assist device 211.

[0140] The control device 306 according to this embodiment differs from the control device 206 according to the second embodiment in that the catalyst temperature Tc detected by the catalyst temperature sensor 312 is input to the control device 306, and a catalyst temperature threshold Tct, which is a threshold value for the catalyst temperature Tc, is stored in the second storage device 306d. Note that in FIG. 18 , the device that inputs data to the control device 306 does not have the start-up confirmation sensor 210, and the device that outputs command data from the control device 206 does not have the start-up auxiliary device 211, but the device that inputs data to the control device 306 may have the start-up confirmation sensor 210, and the device that outputs command data from the control device 206 may have the start-up auxiliary device 211.

[0141] Furthermore, the flow executed by the control device 306 of this embodiment at takeoff differs from the flow executed by the control device 206 of the second embodiment at takeoff in that it includes a takeoff step 307 that determines whether the catalyst temperature Tc is equal to or lower than the catalyst temperature threshold value Tct.

[0142] 19 does not include a takeoff step 207 for determining whether or not the distance D from the urban area detected by the position receiver 209 is equal to or greater than the distance threshold Dt, but the takeoff step 207 may be executed together with the takeoff step 307. Also, the takeoff step 206 for determining whether or not the internal combustion engine 5 has started and the takeoff step 209 for attempting to start the internal combustion engine 5 by the starting assist device 211 are not provided, but these steps may be provided as in the second embodiment.

[0143] Specifically, the flow executed by the control device 306 at the time of takeoff in FIG. 19 is initiated in response to an operation by the operator to start operating the electric aircraft. As in the second embodiment, in a takeoff step 201, the control device 306 reads the remaining battery capacity SOC of the storage battery 3 and determines whether the remaining battery capacity SOC is equal to or greater than the takeoff SOCt. In a takeoff step 202, the control device 306 supplies power from the storage battery 3 to the motor 2 and starts the rotor 1. In a takeoff step 203, the control device 306 determines whether the electric aircraft 300 has taken off. In a takeoff step 204, the control device 306 determines whether the remaining battery capacity SOC is equal to or less than the lower limit threshold Lt, whether the cooling water temperature Tw is equal to or less than the water temperature threshold Twt, whether the air temperature Ta is equal to or less than the air temperature threshold Tat, and whether the air pressure Pa is equal to or less than the air pressure threshold Pat. If the determination in the takeoff step 204 is YES, the control device 306 proceeds to a takeoff step 205.

[0144] If the battery remaining charge SOC is not equal to or lower than the lower limit threshold Lt, the coolant temperature Tw is not equal to or lower than the water temperature threshold Twt, the air temperature Ta is not equal to or lower than the air temperature threshold Tat, or the air pressure Pa is not equal to or lower than the air pressure threshold Pat (NO), the control device 306 determines in the takeoff step 307 whether the catalyst temperature Tc is not equal to or lower than the catalyst temperature threshold Tct.

[0145] If the catalyst temperature Tc is below the catalyst temperature threshold Tct (YES), the purification performance of the exhaust catalyst 305 will be significantly reduced, causing large amounts of harmful substances to be emitted from the internal combustion engine 5. Therefore, in the takeoff step 205, the internal combustion engine 5 is started to prevent the catalyst temperature Tc from decreasing further.

[0146] If the catalyst temperature Tc exceeds the catalyst temperature threshold Tct (NO), the process proceeds to takeoff step 208, where it is determined whether the altitude H of the electric aircraft 200 has reached the altitude threshold Ht, and in step 205, the internal combustion engine 5 is started, and the takeoff processing is terminated.

[0147] [Effect] The electric aircraft 300 of this embodiment further includes an exhaust catalyst 305 provided in the piping of the internal combustion engine 5, and a catalyst temperature sensor 312 that detects the catalyst temperature Tc of the exhaust catalyst 305, and the control device 306 determines whether the catalyst temperature Tc detected by the catalyst temperature sensor 312 is equal to or lower than a catalyst temperature threshold Tct, and if the catalyst temperature Tc is equal to or lower than the catalyst temperature threshold Tct, it is preferable to start the internal combustion engine 5 and generate electricity using the generator 4.

[0148] This prevents the catalyst temperature Tc detected by the catalyst temperature sensor 312 from falling below the catalyst temperature threshold Tct, which would significantly reduce the purification performance of the exhaust catalyst 305 and prevent large amounts of harmful substances from being emitted from the internal combustion engine 5.

[0149] It is preferable that the step of determining whether the catalyst temperature Tc detected by the catalyst temperature sensor 312 is equal to or lower than the catalyst temperature threshold Tct (takeoff step 307) be performed after the electric aircraft 200 has taken off, after the step of determining whether the physical quantity detected by the environmental sensor 208 has reached a physical quantity threshold, or whether the detection value detected by any of the multiple start-up condition sensors of the internal combustion engine 5 has reached a threshold (takeoff step 204).

[0150] This prevents the internal combustion engine 5 from being unable to start when the catalyst temperature Tc detected by the catalyst temperature sensor 312 falls below the catalyst temperature threshold Tct and an attempt is made to start the internal combustion engine 5, thereby improving the flight safety of the electric aircraft 200.

[0151] Furthermore, the step of determining whether the catalyst temperature Tc detected by the catalyst temperature sensor 312 is equal to or lower than the catalyst temperature threshold Tct (takeoff step 307) is preferably executed before the step of determining whether the altitude H of the electric aircraft 200 is equal to or higher than the altitude threshold Ht (takeoff step 208). This allows the internal combustion engine 5 to be started earlier, thereby preventing a large amount of harmful substances from being emitted from the internal combustion engine 5.

[0152] The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0153] Furthermore, the above-described configurations, functions, etc. may be partially or entirely implemented in hardware, for example, by designing them as integrated circuits. Furthermore, the above-described configurations, functions, etc. may be implemented in software, with a processor (microcomputer) interpreting and executing a program that implements each function. Information such as the program, table, and file that implements each function can be stored in a memory, a recording device such as a hard disk or SSD (Solid State Drive), or a recording medium such as an IC card, SD card, or DVD.

[0154] The embodiment of the present invention may be configured as follows: For example, one of the multiple start-up condition sensors that detect the start-up condition of the internal combustion engine 5 may be a sensor that detects the temperature of the engine oil of the internal combustion engine 5, and in the takeoff step 204, it may be determined whether the engine oil temperature detected by this sensor is equal to or lower than a threshold value (the minimum temperature for starting the internal combustion engine 5), and if the detected value reaches the threshold value, the internal combustion engine 5 may be started and the generator 4 may generate electricity.

[0155] 1...rotor, 2...motor, 3...storage battery, 4...generator, 5...internal combustion engine, 6...controller, 7...altitude acquisition device, 8...environmental sensor, 100, 200, 300...electric aircraft, 203...battery remaining capacity sensor, 205...water temperature sensor, 209...position receiver, 210...start confirmation sensor, 211...starting auxiliary device, 305...exhaust catalyst, 312...catalyst temperature sensor

Claims

1. A control device for controlling an electric aircraft comprising a motor that drives a rotor, a storage battery that supplies power to the motor, a generator that is powered by an internal combustion engine and can supply power to the motor and the storage battery, and an altitude acquisition device that acquires flight altitude, wherein the control device supplies power from the storage battery to the motor while the internal combustion engine is stopped, causing the electric aircraft to take off, and after the electric aircraft has taken off, determines whether the altitude of the electric aircraft acquired by the altitude acquisition device is equal to or greater than an altitude threshold, and if the altitude of the electric aircraft is equal to or greater than the altitude threshold, starts the internal combustion engine.

2. A control device for an electric aircraft as described in claim 1, wherein the electric aircraft further comprises an environmental sensor that detects a physical quantity around the electric aircraft, and the control device determines whether or not the physical quantity detected by the environmental sensor has reached a threshold value for the physical quantity after the electric aircraft has taken off, and if the physical quantity has reached the threshold value, starts the internal combustion engine and generates electricity using the generator.

3. A control device for an electric aircraft as described in claim 1, wherein the electric aircraft further comprises a plurality of start-up condition sensors that detect the start-up conditions of the internal combustion engine, and the control device determines whether or not a detection value detected by any of the plurality of start-up condition sensors has reached a threshold value after the electric aircraft has taken off, and if the detection value has reached the threshold value, starts up the internal combustion engine and generates electricity with the generator.

4. A control device for an electric aircraft as described in claim 2, wherein the environmental sensor is an air temperature sensor that detects the air temperature around the electric aircraft, and the control device determines whether the air temperature detected by the air temperature sensor is below a threshold air temperature after the electric aircraft takes off, and if the air temperature detected by the air temperature sensor becomes below the threshold air temperature, starts the internal combustion engine and generates electricity using the generator.

5. A control device for an electric aircraft as described in claim 2, wherein the environmental sensor is a barometric pressure sensor that detects the barometric pressure around the electric aircraft, and the control device determines whether the barometric pressure detected by the barometric pressure sensor is below a barometric pressure threshold after the electric aircraft takes off, and if the barometric pressure detected by the barometric pressure sensor becomes below the barometric pressure threshold, starts up the internal combustion engine and generates electricity using the generator.

6. A control device for an electric aircraft as described in claim 2, wherein the environmental sensor is a humidity sensor that detects the humidity around the electric aircraft, and the control device determines whether the humidity detected by the humidity sensor is equal to or higher than a humidity threshold value after the electric aircraft takes off, and if the humidity detected by the humidity sensor is equal to or higher than the humidity threshold value, starts up the internal combustion engine and generates electricity using the generator.

7. A control device for an electric aircraft as described in claim 3, wherein one of the multiple start-up condition sensors is a water temperature sensor that detects the temperature of the cooling water for the internal combustion engine, and the control device determines whether the water temperature detected by the water temperature sensor is below a water temperature threshold after the electric aircraft takes off, and if the water temperature detected by the water temperature sensor becomes below the water temperature threshold, starts up the internal combustion engine and generates electricity using the generator.

8. A control device for an electric aircraft as described in claim 3, wherein one of the multiple start-up condition sensors is a battery remaining capacity sensor that detects the remaining battery capacity of the storage battery, and the control device determines whether the remaining battery capacity detected by the battery remaining capacity sensor is below a lower threshold value after the electric aircraft takes off, and if the remaining battery capacity detected by the battery remaining capacity sensor falls below a lower threshold value, starts up the internal combustion engine and generates electricity using the generator.

9. A control device for an electric aircraft as described in claim 1, wherein the electric aircraft further comprises a position receiver that calculates the position of the electric aircraft based on positioning signals received from a plurality of positioning satellites, and the control device determines, after the electric aircraft takes off, whether the distance between the electric aircraft and an urban area detected by the position receiver is equal to or greater than a distance threshold, and if the distance between the electric aircraft and the urban area detected by the position receiver is equal to or greater than the distance threshold, starts the internal combustion engine and generates electricity using the generator.

10. A control device for an electric aircraft as described in claim 1, wherein the electric aircraft further comprises a catalyst provided in an exhaust pipe of an internal combustion engine and a catalyst temperature sensor that detects the temperature of the catalyst, and the control device determines whether or not the temperature detected by the catalyst temperature sensor is below a catalyst temperature threshold after the electric aircraft takes off, and if the temperature detected by the catalyst temperature sensor becomes below the catalyst temperature threshold, starts the internal combustion engine and generates electricity using the generator.

11. A control device for an electric aircraft as described in claim 3, wherein one of the multiple start-up condition sensors is a fuel temperature sensor that detects the temperature of fuel in the internal combustion engine, and the control device starts the internal combustion engine and generates electricity with the generator when the fuel temperature detected by the fuel temperature sensor becomes equal to or lower than a fuel temperature threshold value after the electric aircraft takes off.

12. A control device for an electric aircraft as described in claim 8, characterized in that the control device does not supply power from the storage battery to the motor if the remaining battery charge detected by the battery remaining charge sensor before the takeoff of the electric aircraft is less than the takeoff battery remaining charge, which is the battery remaining charge required for takeoff.

13. A control device for an electric aircraft as described in claim 1, wherein the electric aircraft further comprises a start confirmation sensor that confirms the start of the internal combustion engine, and a start auxiliary device that assists the start of the internal combustion engine, and the control device determines whether or not the internal combustion engine should be started based on the detection value of the start confirmation sensor, and if the internal combustion engine is not started, starts the internal combustion engine using the start auxiliary device and generates electricity with the generator.

14. A control device for an electric aircraft as described in claim 1, characterized in that, when landing the electric aircraft, the control device determines whether the altitude of the electric aircraft is below the altitude threshold, and if the altitude of the electric aircraft is below the altitude threshold, stops the internal combustion engine and drives the motor using only the power supplied from the storage battery to land the electric aircraft.

15. A control method for controlling an electric aircraft comprising a motor that drives a rotor, a storage battery that supplies power to the motor, a generator that is powered by an internal combustion engine and can supply power to the motor and the storage battery, and an altitude acquisition device that acquires flight altitude, the control method for an electric aircraft comprising the steps of: supplying power from the storage battery to the motor while the internal combustion engine is stopped, causing the electric aircraft to take off, determining after the electric aircraft has taken off whether the altitude of the electric aircraft acquired by the altitude acquisition device is equal to or greater than an altitude threshold, and starting the internal combustion engine if the altitude of the electric aircraft is equal to or greater than the altitude threshold.

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