Rotor aircraft

Abstract

The present specification provides a rotorcraft capable of suppressing a temperature rise of a fuel cell more effectively than conventionally using an air flow of a rotor. A rotorcraft disclosed in the present specification is provided with: a rotor for generating lift force; a hydrogen source; and a flow path pipe for conveying hydrogen from the hydrogen source to the fuel cell stack. And the flow path pipe passes through the lower part of the rotor. A rotorcraft disclosed in this specification utilizes an airflow generated by a rotor to cool hydrogen prior to entering a fuel cell stack. A rotorcraft disclosed in the present specification can suppress a temperature increase in a fuel cell stack by supplying cooled hydrogen to the fuel cell stack.

Description

TECHNICAL FIELD

[0001] The technology disclosed in this specification relates to a rotorcraft. The rotorcraft in this specification includes, in addition to manned aircraft such as helicopters and autogiros, unmanned so-called drones. BACKGROUND

[0002] A rotorcraft is disclosed in Patent Literature 1, which is provided with a fuel cell and a radiator that cools the fuel cell. The radiator is cooled by wind during flight. Further, a rotorcraft is disclosed in Patent Literature 2, which is provided with a heat sink arranged at a position where it is subjected to airflow generated by a rotor.

[0003] Patent Literature 1: Japanese Patent Application Publication No. 2022-118983

[0004] Patent Literature 2: Japanese Patent Application Publication No. 2020-152143 SUMMARY

[0005] The present specification provides a rotorcraft that can more effectively suppress temperature rise of a fuel cell using airflow of a rotor than in the past.

[0006] The rotorcraft disclosed in this specification is provided with a rotor that generates lift, a hydrogen source, and a flow path pipe that transports hydrogen from the hydrogen source to a fuel cell stack. The flow path pipe passes below the rotor. The rotorcraft disclosed in this specification cools hydrogen before it enters the fuel cell stack using airflow generated by the rotor. The rotorcraft disclosed in this specification can suppress temperature rise of the fuel cell stack by supplying cooled hydrogen to the fuel cell stack.

[0007] The flow path pipe extends in a direction parallel to an axis of the rotor. It is possible to extend the range of the flow path pipe that receives airflow of the rotor, and it is possible to suppress airflow turbulence caused by the flow path pipe.

[0008] The rotorcraft sometimes has a plurality of rotors. In this case, the flow path pipe passes below at least two rotors. With this structure, it is also possible to extend the range of the flow path pipe that receives airflow of the rotors.

[0009] Details and further improvements of the technology disclosed in this specification will be described in the following “DETAILED DESCRIPTION”. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 is a plan view of a rotorcraft of Embodiment 1.

[0011] Figure 2 is a side view of a rotorcraft.

[0012] Figure 3 is a front view of a rotorcraft.

[0013] Figure 4 is a front view of the rotorcraft of the second embodiment. DETAILED DESCRIPTION

[0014] (First Embodiment) Reference Figures 1-3 The rotorcraft 10 of the first embodiment will be described. Figures 1-3 are a plan view, a side view, and a front view of the rotorcraft, respectively. The X axis and the Y axis of the coordinate system in the drawing represent the front-rear direction and the lateral direction of the rotorcraft 10, respectively. The +Z direction represents the vertical upward direction.

[0015] The rotorcraft 10 is a so-called unmanned aerial vehicle that flies by remote operation. The rotorcraft 10 is provided with a main body 11, four rotors 12, a hydrogen source 15, a fuel cell stack 16, and a flow path pipe 17. Hereinafter, for convenience of explanation, the "fuel cell stack" will be expressed as "FC stack".

[0016] The rotorcraft 10 flies by generating lift with the four rotors 12. The four rotors 12 are arranged on the four corners of the main body 11, respectively. The rotors 12 are driven by motors 13. The motors 13 are driven by electric power generated by the FC stack 16. In addition, a battery is provided in the main body 11, and the remaining electric power, which is not consumed by the motors 13, of the electric power generated by the FC stack 16 is stored in the battery. In the case where the FC stack 16 is insufficient in electric power for driving the motors 13, the electric power of the battery is used. A device that converts the electric power generated by the FC stack 16 (and the electric power of the battery) into electric power suitable for driving the motors 13 is mounted in the main body 11, but the drawing and the description of the device are omitted.

[0017] The hydrogen source 15 is arranged on the main body 11. Sodium borohydride (SBH) and water are stored in the hydrogen source 15. The hydrogen source 15 generates hydrogen by mixing water in the SBH. The SBH and the water are stored in the hydrogen source 15 at normal pressure, respectively. In a fuel cell vehicle or the like, a high-pressure hydrogen tank is generally used as a hydrogen source, but the high-pressure hydrogen tank increases in weight in order to obtain high pressure resistance. The hydrogen source 15 of the rotorcraft 10 stores the SBH and the water at normal pressure, and thus the dry weight (weight excluding the SBH and the water) is lighter than that of the high-pressure hydrogen tank, and is suitable for the rotorcraft 10 that flies by electric power.

[0018] The FC stack 16 is arranged below the main body 11, and the hydrogen source 15 and the FC stack 16 are connected by the flow path pipe 17. Hydrogen generated by the hydrogen source 15 is supplied to the FC stack 16 through the flow path pipe 17. As shown in the front view ( Figure 3 ), for convenience of explanation, the flow path pipe 17 that connects the hydrogen source 15 and the FC stack 16 is divided into a flow path pipe upper portion 17a, flow path pipe intermediate portions 17b, 17c, and a flow path pipe lower portion 17d. Also, for convenience of explanation, the rotors 12 shown on the left side of the front view are indicated by symbols 12a, and the rotors 12 shown on the right side of the front view are indicated by symbols 12b. Figure 3 Figure 3 ​The rotor 12 shown on the right side of the figure is indicated by the symbol 12b.

[0019] The flow path pipe upper portion 17a is connected to the hydrogen source 15 and is divided into two at the middle. The flow path pipe upper portion 17a extends to below the left and right rotors 12a, 12b. The upper end of the flow path pipe middle portion 17b is connected to the left end of the flow path pipe upper portion 17a, and the upper end of the flow path pipe middle portion 17c is connected to the right end of the flow path pipe upper portion 17a. The flow path pipe middle portion 17b (17c) extends below the rotor 12a (12b) along the axis Ax of the rotor 12a (12b). The flow path pipe lower portion 17d is connected to the FC stack 16 and is divided into two at the middle. The lower end of the flow path pipe middle portion 17b is connected to the left end of the flow path pipe lower portion 17d, and the lower end of the flow path pipe middle portion 17c is connected to the right end of the flow path pipe lower portion 17d. The hydrogen generated by the hydrogen source 15 is divided into two at the flow path pipe upper portion 17a and flows below the rotors 12a, 12b along the axes Ax of the rotors 12a, 12b. Then, the hydrogen converges at the flow path pipe lower portion 17d and flows to the FC stack 16.

[0020] In flight, the helicopter 10 pushes air below the rotors 12 to generate lift. In flight, the air flows below the rotors 12 along the axes Ax. A part of the flow path pipe 17 (the flow path pipe middle portions 17b, 17c) extends along the axes Ax, and the hydrogen flowing in the flow path pipe middle portions 17b, 17c is cooled by the air flow. The helicopter 10 has four legs 14, and the flow path pipe middle portions 17b, 17c extend to near the lower ends of the legs 14. In addition, the illustration of the legs 14 is omitted in Figure 1 The flow path pipe middle portions 17b, 17c extend along the axes Ax, and thus the hydrogen is cooled by the air flow over a relatively long distance. By providing the flow path pipe 17 that extends long along the axes Ax, the hydrogen is effectively cooled. In addition, the flow path pipe 17 is made of metal (typically copper) having a high thermal conductivity.

[0021] The FC stack 16 generates electric power by reacting hydrogen with oxygen (air). Heat is also emitted when hydrogen reacts with oxygen. Normally, a fuel cell has a cooler that cools the FC stack, but the cooler of the fuel cell includes a pump or the like, and thus the weight increases. The helicopter 10 suppresses the temperature rise of the FC stack 16 by cooling the hydrogen using the air flow of the rotors 12 and supplying the cooled hydrogen to the FC stack 16. The helicopter 10 does not need to have a cooler that is complex in structure and heavy. The extension of the flow path pipe 17 to below the plurality of rotors 12 also contributes to the effective cooling of the hydrogen.

[0022] (Second Embodiment) Figure 4 A front view of a helicopter 20 of a second embodiment is shown in FIG. 2. The flow path pipe 27 of the helicopter 20 is different from that of the helicopter 10 of the first embodiment. The structure of the helicopter 20 is the same as that of the helicopter 10 of the first embodiment except for the flow path pipe 27.

[0023] The flow path pipe 27 has a flow path pipe upper portion 27a, two flow path pipe middle portions 27b, 27c, and a flow path pipe lower portion 27d. The flow path pipe upper portion 27a and the flow path pipe lower portion 27d are the same as the flow path pipe upper portion 17a and the flow path pipe lower portion 17d of the hydrogen source 15 of the embodiment. The two flow path pipe middle portions 27b, 27c extend along the axis Ax of the rotor 12 macroscopically. Of the two flow path pipe middle portions 27b, 27c, the two flow path pipe middle portions 27b, 27c are curved in a zigzag shape microscopically. The two flow path pipe middle portions 27b, 27c are curved in a zigzag shape to increase the flow path length, and can cool hydrogen more effectively. Figure 3

[0024] Notes related to the technology described in the embodiment are described. The hydrogen source 15 of the rotorcraft 10, 20 of the embodiment is a device that generates hydrogen by mixing water in the SBH. The hydrogen source 15 can be a device that generates hydrogen from a compound other than the SBH. Alternatively, the hydrogen source 15 can be a tank that stores hydrogen or a hydrogen storage alloy. That is, the hydrogen source 15 can be a device that generates hydrogen or a reservoir that stores hydrogen. Of the hydrogen source 15, it is preferable that the device supply hydrogen at room temperature. This is because the rotorcraft disclosed in the present specification cools hydrogen supplied to the FC stack 16 by the airflow of the rotor.

[0025] The flow path pipe 17 (27) of the rotorcraft 10 (20) of the embodiment is bifurcated from the hydrogen source 15, curved downward below the two rotors 12a, 12b, and extends along the axes of the rotors 12a, 12b, and then converges to be connected to the FC stack 16. This structure can increase the proportion of the total length of the flow path pipe that passes below the rotors 12. That is, this structure of the flow path pipe is lightweight and provides high cooling efficiency.

[0026] The rotorcraft 10 (20) of the embodiment has a plurality of rotors 12, and the flow path pipe 17 (27) passes below at least the two rotors 12. The rotorcraft disclosed in the present specification can pass below at least one rotor. A portion of the flow path pipe can extend along the axis of the rotor directly below the rotor.

[0027] ​If the viewpoint is changed, the hydrogen flowing in the flow path pipe can be considered as a refrigerant that cools the FC stack. That is, if the viewpoint is changed, the rotorcraft disclosed in the present specification is characterized in that the downward airflow generated by the rotor is used to cool the refrigerant. If based on this viewpoint, it can be stated that the rotorcraft of the embodiment has the following characteristics. The rotorcraft 10 (20) disclosed in the present specification has a rotor 12 that generates lift and a flow path pipe (flow path pipe intermediate portions 17b, 17c, 27b, 27c) that extends along the axis Ax of the rotor 12 below the rotor 12. A refrigerant flows in the flow path pipe 17 (27), and the refrigerant that passes through the flow path pipe is sent to the heat generating body (FC stack 16) possessed by the rotorcraft 10 (20). By having the flow path pipe (flow path pipe intermediate portions 17b, 17c, 27b, 27c) that extends along the axis Ax below the rotor 12, the rotorcraft 10 (20) can efficiently cool the refrigerant without significantly increasing the weight. This rotorcraft can more efficiently cool the refrigerant than in the past using the airflow of the rotor. From this viewpoint, the heat generating body can be a component other than the FC stack, and the refrigerant can be a substance other than hydrogen (for example, water).

[0028] The rotorcraft 10 (20) has a plurality of rotors 12, and the flow path pipe (flow path pipe intermediate portions 17b, 17c, 27b, 27c) can be disposed below at least two rotors 12. The refrigerant can be more efficiently cooled.

[0029] The above has described the specific examples of the present application in detail, but these are merely examples and do not limit the scope of the claims. The technology recited in the claims includes technology in which various modifications and changes are made to the above-described specific examples. The technical elements described in the specification or the drawings singly or through various combinations exhibit technical usefulness and are not limited to the combinations recited in the claims at the time of filing. Also, the technology exemplified in the specification or the drawings can achieve multiple purposes at the same time, and achieving only one purpose itself also has technical usefulness.

[0030] Symbol explanation

[0031] 10, 20 - rotorcraft, 11 - main body, 12, 12a, 12b - rotor, 13 - motor, 14 - leg, 15 - hydrogen source, 16 - fuel cell stack, 17, 27 - flow path pipe, 17a, 27a - flow path pipe upper portion, 17b, 17c, 27b, 27c - flow path pipe intermediate portion, 17d, 27d - flow path pipe lower portion.

Claims

1. A rotary-wing aircraft, characterized in that, have: The rotor generates lift. Hydrogen source; Fuel cell stacks; and A flow path pipe, which supplies hydrogen from the hydrogen source to the fuel cell stack, The flow path pipe passes below the rotor.

2. The rotorcraft according to claim 1, characterized in that, The flow path extends in a direction parallel to the axis of the rotor.

3. The rotorcraft according to claim 1 or 2, characterized in that, It has multiple rotors, and the flow path passes under at least two of the rotors.

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