JP7661925B2 - Aircraft - Google Patents

Description

This application relates to an aircraft.

In recent years, aircraft equipped with fuel cell systems have been developed. For example, Patent Document 1 describes an aircraft power supply system that includes a battery and a fuel cell.

JP 2007-15423 A

In aircraft equipped with fuel cells and secondary batteries, if excess power generated to avoid high potential in the fuel cell, for refresh operation, or for rapid warm-up is charged into the secondary battery, there is a risk of fire due to overcharging. Such issues are of major concern in terms of safety.

Therefore, in view of the above-mentioned circumstances, the main objective of this application is to provide an aircraft that can prevent secondary batteries from catching fire due to overcharging.

As one means for solving the above problems, the present disclosure provides an aircraft that includes a fuel cell, a secondary battery, a motor that drives a propulsion propeller, an air resistance increasing device capable of increasing air resistance, and a control unit, the fuel cell, the secondary battery, and the motor are electrically connected, the motor is driven by obtaining power from at least one of the fuel cell and the secondary battery, and when the fuel cell generates an amount of power that exceeds the amount of power consumed, the control unit increases the amount of power supplied from the fuel cell to the motor while activating the air resistance increasing device to increase air resistance and maintain a flying state, thereby performing power consumption control.

In the above flying object, the air resistance increasing device may be a secondary control surface, and air resistance may be increased by opening the secondary control surface in both directions during power consumption control. In addition, when the fuel cell generates an amount of power that exceeds the amount of power consumed, and the amount of power that exceeds the amount of power consumed is set as surplus power, the control unit may perform power consumption control when the amount of surplus power exceeds a first threshold, and may stop power consumption control when the amount of surplus power falls below a second threshold.

The flying object disclosed herein performs a predetermined power consumption control when the fuel cell generates an amount of power that exceeds the amount of power consumed, i.e., when surplus power occurs. This allows the surplus power to be consumed, and makes it possible to prevent the secondary battery from catching fire due to overcharging.

1 is a schematic diagram of an aircraft 10. (a) is a front view of the aircraft 10, and (b) is a top view of the aircraft 10. 2 is a schematic diagram of the voltage system of the aircraft 10. FIG. FIG. 11 is a diagram for explaining power consumption control in which a threshold value is set. 13 is an example of a processing routine for power consumption control in which a threshold value is set.

The flying object of the present disclosure will be described using flying object 10 as one embodiment. Figure 1 shows a schematic diagram of flying object 10. Figure 1(a) is a front view of flying object 10, and Figure 1(b) is a top view of flying object 10. Figure 2 is a schematic diagram of the voltage system of flying object 10.

The flying object 10 is not particularly limited as long as it is an object capable of flying in the air. For example, the flying object 10 includes aircraft such as general aircraft, light aircraft, and drones. Figure 1 shows the flying object 10 in the form of an aircraft.

The flying object 10 comprises a fuel cell 1, a secondary battery 2, a motor 3 that drives a propulsion propeller 4, an air resistance increaser capable of increasing air resistance, and a control unit. As shown in FIG. 2, the fuel cell 1, the secondary battery 2, and the motor 3 are electrically connected, and the motor 3 is driven by obtaining power from at least one of the fuel cell 1 and the secondary battery 2. Note that FIG. 2 also shows an FDC (DC/DC converter for fuel cell) and an INV (inverter), which are general-purpose devices.

The fuel cell 1 is made by stacking multiple fuel cell units (sometimes simply called "unit cells") in series. The unit cell has an electrolyte membrane, an anode arranged on one side of the electrolyte membrane, and a cathode arranged on the other side of the electrolyte membrane. Specifically, catalyst layers are arranged on both sides of the electrolyte membrane, a diffusion layer is arranged on the outside of the catalyst layer, and a separator with a fuel gas flow path and an oxidant gas flow path is arranged on the outside of the diffusion layer. This type of fuel cell has a general configuration. Here, in the fuel cell, the catalyst layer and the diffusion layer function as the anode or cathode.

The electrolyte membrane, catalyst layer, diffusion layer, and separator arranged in the fuel cell are not particularly limited, and known materials can be used. For example, the electrolyte membrane can be an ion exchange membrane made of a solid polymer material. The catalyst layer can be a platinum-based catalyst. The diffusion layer can be a porous material such as a carbon material. The separator can be a metal material such as stainless steel, or a carbon material such as a carbon composite material.

The fuel cell 10 generates electricity through an electrochemical reaction when fuel gas is supplied to the anode and oxidant gas is supplied to the cathode. The generated electricity is used to charge the secondary battery 2 and drive the motor 3. It may also be used for other devices on the aircraft 10.

The secondary battery 2 is a known secondary battery such as a lithium ion secondary battery. The secondary battery 2 serves to drive the motor 3 and to store the electricity generated by the fuel cell 1. It may also be used for other devices in the aircraft 10.

The air resistance increasing device is not particularly limited as long as it is a control surface that can increase the air resistance of the aircraft 10. For example, a secondary control surface 5 can be used. A secondary control surface is an auxiliary control surface other than the main control surface. Examples of the secondary control surface 5 include spoilers, flaps, and tabs. FIG. 1 shows an example in which a spoiler is used as the secondary control surface 5. In FIG. 1, the secondary control surface 5 is provided on a pair of main wings 6, a pair of tails 7, and a vertical tail 8. The secondary control surface 5 is composed of a pair of flat plates, and usually, one or both of the flat plates are opened to change the air resistance and control the movement of the aircraft 10. As shown in FIG. 1, the secondary control surfaces 5 provided on the main wings 6 and tail 7 have flat plates arranged above and below, and the secondary control surface 5 provided on the vertical tail 8 has flat plates arranged on the left and right. This configuration is similar to the configuration of a general secondary control surface.

The control unit is a computer system equipped with a CPU, ROM, RAM, and an input/output interface, and controls each part of the aircraft 10.

As mentioned above, the power generated by the fuel cell 1 may be used to charge the secondary battery 2. Normally, the power generation of the fuel cell 1 is controlled so that the secondary battery 2 does not exceed the charging allowable power. However, if power is generated to avoid a high potential of the fuel cell 1, for refresh operation, rapid warm-up, etc., and the amount of power generated exceeds the amount of power consumed, when the amount of power exceeding the amount of power consumed (surplus power) is charged to the secondary battery 2, it may exceed the charging allowable power amount and become overcharged. If the secondary battery 2 is overcharged, there is a problem of it catching fire. Suppressing ignition of such secondary battery 2 is an important issue for improving the safety of the flying object 10.

In view of this, in the flying object 10, when the fuel cell 1 generates an amount of power that exceeds the amount of power consumed, the control unit increases the amount of power supplied from the fuel cell 1 to the motor 3, while activating the air resistance increasing device to increase air resistance and maintain the flying state, thereby performing power consumption control. This allows the flying state to be maintained while consuming surplus power, and makes it possible to prevent the secondary battery from catching fire due to overcharging.

Here, each term will be explained.
The "allowable charging power amount" is the amount of charging that does not result in overcharging. In other words, if the amount of charging exceeds the allowable charging power amount, the secondary battery 2 will be overcharged.
"Power consumption" refers to the amount of power consumption required to operate the aircraft 10. The amount of power consumption varies depending on the operating state of the aircraft 10, etc.
The term "surplus power" refers to the amount of power that exceeds the amount of power consumed when the fuel cell 1 generates an amount of power that exceeds the amount of power consumed.

"High potential avoidance" refers to power generation to prevent the voltage of the fuel cell 1 from rising above a predetermined voltage. If the voltage of the fuel cell 1 rises to the predetermined voltage, the metal (e.g., platinum) used in the catalyst layer will ionize and dissolve.
The "refresh operation" refers to power generation for lowering the voltage of the fuel cell 1 in order to remove the oxide film of the metal (eg, platinum) used in the catalyst layer.
"Rapid warm-up" refers to power generation for self-heating the fuel cell 1 to prevent it from freezing.

"Power consumption control" refers to control performed by the control unit to consume surplus power. In power consumption control, thrust increase control is performed to increase the amount of power supplied from the fuel cell 1 to the motor 3, and air resistance increase control is performed to increase air resistance by operating the air resistance increase device. At this time, thrust increase control and air resistance increase control must be performed to maintain the flight state. "Maintaining the flight state" means that there is almost no change in thrust and lift before and after the power consumption control. "Almost no change" means that the change in thrust and lift before and after the power consumption control is within ±10%, preferably within ±5%.

Therefore, power consumption control can be said to be control that consumes surplus power while maintaining the flight state by increasing the thrust or lift of the flying body 10 while increasing air resistance. Here, the order in which the thrust increase control and the air resistance increase control are performed is not particularly limited, and they may be performed sequentially or simultaneously. If they are performed sequentially, either control may be performed first.

The amount of increase in the amount of power supplied to the motor 3 is not particularly limited, but may be a portion or the entire amount of surplus power. When the air resistance device is a secondary control surface 5, the air resistance can be increased by opening one or both of the secondary control surfaces 5. Preferably, the secondary control surfaces 5 are opened in both directions. As shown in FIG. 1, when the aircraft 10 is equipped with multiple secondary control surfaces 5, all of the secondary control surfaces 5 equipped on the aircraft 10 may be opened, or some of the secondary control surfaces 5 may be opened. By using the secondary control surfaces 5 as an air resistance increasing device, power consumption control can be performed without providing an additional device.

The control unit may also perform power consumption control as follows. That is, the control unit may perform power consumption control when the amount of surplus power exceeds a first threshold, and may stop power consumption control when the amount of surplus power falls below a second threshold. This makes it possible to reduce the number and duration of power consumption control while preventing overcharging of the secondary battery, thereby improving fuel efficiency.

The "first threshold" can be set appropriately from the range of the chargeable electric energy amount that can suppress overcharging of the secondary battery 1 by performing power consumption control when surplus electric energy occurs, taking fuel consumption into consideration. For example, it can be appropriately selected from the range of 30% to 70%, preferably 40% to 60%, of the chargeable electric energy amount.
The "second threshold" can be set appropriately from the range of the chargeable electric energy amount that can suppress overcharging of the secondary battery 1 without performing power consumption control when surplus electric energy occurs, taking fuel consumption into consideration. For example, it can be appropriately selected from the range of 0% to 30%, preferably 10% to 20%, of the chargeable electric energy amount.

Figure 3 shows a diagram explaining power consumption control with a threshold set. (1) and (2) in Figure 3 indicate the first threshold and the second threshold, respectively. Also, (A) and (B) in Figure 3 indicate the power consumption control in progress and the power consumption control stopped, respectively. As shown in Figure 3, the power consumption control with a threshold set is controlled to draw a hysteresis loop.

Figure 4 shows an example of a processing routine for power consumption control with a set threshold value. As shown in Figure 4, the control unit 50 has processes S1 to S6, and the control unit 50 repeats these processes.

In process S1, it is determined whether the amount of surplus power exceeds a first threshold. If it is determined that the amount of surplus power exceeds the first threshold, power consumption control (processes S2 and S3) is performed.

In process S2, thrust increase control is performed to increase the amount of power supplied from the fuel cell 1 to the motor 3. In process S3, air resistance increase control is performed to increase air resistance by operating the air resistance increase device. Here, when performing both processes S2 and S3, control is performed to maintain the flight state.

In process S4, it is determined whether the amount of surplus power is below the second threshold. If the amount of surplus power is below the second threshold, power consumption control is stopped (processes S5 and S6).

In process S5, thrust increase control is stopped. In process S6, air resistance increase control is stopped. Here, when performing both processes S5 and S6, it is preferable to control so as to maintain the flight state.

The above describes the flying object of the present disclosure using flying object 10, which is one embodiment. The flying object of the present disclosure performs a predetermined power consumption control when the fuel cell generates an amount of power that exceeds the amount of power consumed, i.e., when surplus power occurs. Therefore, with the flying object of the present disclosure, it is possible to consume the surplus power while maintaining a flying state, and to prevent the secondary battery from catching fire due to overcharging.

1 Fuel cell 2 Secondary battery 3 Motor 4 Propeller 5 Secondary control surface 6 Main wing 7 Tail 8 Vertical stabilizer 10 Aircraft

Claims (2)

The vehicle is provided with a fuel cell, a secondary battery, a motor for driving a propulsion propeller, an air resistance increasing device capable of increasing air resistance, and a control unit,
the fuel cell, the secondary battery, and the motor are electrically connected to each other;
the motor is driven by obtaining electric power from at least one of the fuel cell and the secondary battery,
When the fuel cell generates an amount of electric power that exceeds the amount of electric power consumed, the control unit increases the amount of electric power supplied from the fuel cell to the motor, while operating the air resistance increasing device to increase air resistance and maintain a flying state, thereby performing power consumption control;
When the fuel cell generates an amount of power that exceeds the amount of power consumed, and the amount of power that exceeds the amount of power consumed is determined as surplus power, the control unit performs the power consumption control when the amount of surplus power exceeds a first threshold, and stops the power consumption control when the amount of surplus power falls below a second threshold;
the secondary battery has a role of storing the electric power generated by the fuel cell,
the first threshold value is 30% to 70% of the charge allowable energy,
the second threshold value is 0 to 30% of the charge allowable energy,
the charge allowable amount of electric power is within a range in which the secondary battery is not overcharged;
Flying vehicle. the aerodynamic device is a secondary control surface;
During the power consumption control, the secondary control surface is opened in both directions to increase air resistance.
The flying vehicle according to claim 1.