Hot air recirculation hood and heavy-duty UAV using the hood

Abstract

This invention discloses a hot gas recirculation hood and a heavy-duty UAV using the hood, relating to the field of UAV technology. The proposed solution includes a hot gas recirculation hood comprising: a shell for covering the outside of a fuel cell system stack, with the interior of the shell forming an annular circulating air duct with the fuel cell system stack; a rectifier for discharging waste heat gas generated by the fuel cell system stack to the outside of the shell; a spoiler hood disposed downstream of the exhaust path of the rectifier hood for changing the exhaust direction of the waste heat gas; and an active recirculation component movably disposed on the shell, having a waste gas capture section opposite to the spoiler hood. The movement of the active recirculation component is configured to synchronously adjust the proportion of waste gas recirculated back into the shell via the waste gas capture section, and the flow rate of fresh air entering the shell via the shell, thereby achieving regulation of the working microenvironment of the fuel cell system stack.

Description

Technical Field

[0001] This invention relates to the field of unmanned aerial vehicle (UAV) technology, and more particularly to a hot air recirculation hood and a heavy-duty UAV using the same hood. Background Technology

[0002] Hydrogen fuel cells, with their high energy density and zero emissions, have shown great application potential in the field of drones that require long flight time and heavy payload. However, when integrating hydrogen fuel cell systems into drone platforms, the drone's flight environment is highly variable. Especially in low-temperature and low-humidity environments, the fuel cell stack needs to maintain a suitable operating temperature and prevent the membrane electrode from drying out to ensure start-up performance and operating efficiency. In high-load or normal-temperature environments, waste heat needs to be dissipated quickly to prevent the stack from overheating.

[0003] In existing technologies, active cooling solutions for UAV fuel cell systems are mostly implemented using fixed air ducts and axial fans. While this solution is simple in structure, it has significant shortcomings in addressing the complex and conflicting thermal management requirements mentioned above. Firstly, the heat dissipation ducts are usually open or have a fixed opening, making it impossible to intelligently adjust the ratio of waste heat discharge to retention according to the ambient temperature. This can easily lead to heat loss and performance degradation of the fuel cell stack in low-temperature environments. Secondly, simple fan exhaust cannot effectively organize the airflow around the fuel cell stack, resulting in uneven mixing of hot and cold air. This affects both heat preservation / heat dissipation efficiency and makes it difficult to utilize the moisture in the exhaust gas to humidify the intake air. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to solve the above-mentioned problems.

[0005] To achieve the above-mentioned technical objectives, the present invention provides a hot gas recirculation hood and a heavy-duty UAV using the hood, comprising a hot gas recirculation hood, wherein the hot gas recirculation hood includes: The casing is used to cover the outside of the fuel cell system stack, and the inside of the casing forms a ring-shaped circulating air duct between the fuel cell system stack and the inside of the casing. The fairing is used to exhaust the waste heat gas generated by the fuel cell system stack to the outside of the fairing. The spoiler is located downstream of the exhaust path of the fairing and is used to change the direction of the exhaust of waste heat airflow. An active recirculation assembly is movably mounted on a housing and has an exhaust gas capture section opposite to the spoiler; wherein the movement of the active recirculation assembly is configured to synchronously adjust the proportion of exhaust gas recirculated back into the housing via the exhaust gas capture section, and the flow rate of fresh air entering the housing via the housing.

[0006] Preferably, the rear of the cover is provided with an inclined rear cover for guiding airflow to converge towards its center.

[0007] Preferably, the bottom of the cover has an air inlet for external air to enter.

[0008] Preferably, the active recirculation assembly includes a recirculation bucket as the exhaust gas capture unit, a valve plate connected to the recirculation bucket, and a linear drive unit for driving its movement; The return hopper is slidably and sealed to the cover, and the valve plate is used to adjust the opening area of ​​the air inlet.

[0009] Preferably, the linear drive unit may be a linear actuator, including but not limited to a linear servo, a voice coil motor, or a servo electric cylinder.

[0010] Preferably, the inner wall of the spoiler is fixed with a plurality of arc-shaped spoiler plates converging toward the center of the spoiler.

[0011] Preferably, a side return flow grille is fixed through the side of the cover, and the side return flow grille includes a plurality of inclined grille plates with the inlets of the flow channels facing downwards.

[0012] Preferably, it also includes a detection unit and a control unit; The detection unit is used to collect operating condition data of the hot gas recirculation hood and the fuel cell system stack; The control unit connects the detection unit and the active recirculation component, and is configured to generate control commands for the active recirculation component based on the operating condition data.

[0013] Preferably, the control unit is configured as follows: When it is determined based on the operating condition data that enhanced heat dissipation is needed, the active recirculation component is controlled to move to the first position to minimize exhaust gas recirculation and maximize the intake of fresh air. When it is determined based on the operating data that heat preservation and humidification are required, the active recirculation component is controlled to move to a second position different from the first position, so as to introduce some exhaust gas recirculation and reduce the intake of fresh air.

[0014] A heavy-duty unmanned aerial vehicle using the aforementioned fairing includes a flight section and a power section; The power unit includes a chassis, a fuel cell stack, a hydrogen storage tank for supplying gas to the fuel cell stack, and a cooling fan for dissipating heat from the fuel cell stack. The hot gas recirculation shroud is mounted on the machine stand and covers the outside of the fuel cell system stack, and its shroud is connected to the outlet of the cooling fan.

[0015] As can be seen from the above technical solutions, this application has the following beneficial effects: 1. By setting up a hot gas recirculation hood that includes a cover, fairing, spoiler and active recirculation components, some high-temperature exhaust gas is actively recovered in low-temperature environment to improve the temperature and humidity inside the cavity, and exhaust gas is completely discharged in high-temperature environment to enhance heat dissipation, thereby realizing the regulation of the working microenvironment of the fuel cell system stack. 2. By forming an annular air duct between the inner wall of the casing and the fuel cell stack, combined with the bottom air inlet, the side return flow grille with a specific inclined angle grating, and the synergistic guiding effect of the inclined rear cover, the airflow organization flowing across the surface of the fuel cell stack is optimized, forming an encircling flow. This achieves more complete and uniform mixing and heat exchange between external cold air and internal hot exhaust gas, thereby improving the efficiency and response speed of thermal management and reducing the dependence on the energy consumption of the cooling fan. 3. In conjunction with a sensor-based feedback control unit, adaptive closed-loop control of the working microenvironment of the fuel cell system stack is achieved. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0017] Figure 1 A front view schematic diagram of the hot air recirculation hood and the heavy-duty UAV using the recirculation hood provided by the present invention. Figure 2 A schematic diagram of the overall structure of the flight section of a heavy-duty UAV using the hot air recirculation hood provided by the present invention. Figure 3 A schematic diagram of the overall structure of the power unit of a heavy-duty UAV using the hot air recirculation hood provided by the present invention. Figure 4 A schematic diagram of the overall structure of the hot gas recirculation hood, the hot gas recirculation hood of the heavy-duty UAV using the recirculation hood, and the fuel cell system stack provided by the present invention. Figure 5 A side cross-sectional view of the hot air return hood and the hot air return hood of a heavy-duty UAV using the hood provided by the present invention. Figure 6 A schematic diagram of the overall structure of the hot air recirculation hood and the shell of the heavy-duty UAV using the recirculation hood provided by the present invention. Figure 7 A schematic diagram of the extended state structure of the hot air recirculation hood and the active recirculation component of the heavy-duty UAV using the recirculation hood provided by the present invention. Figure 8A schematic diagram of the overall structure of the hot air recirculation hood and the shell of the heavy-duty UAV using the recirculation hood provided by the present invention. Figure 9 A schematic diagram of the exploded structure of the hot gas recirculation hood and the hot gas recirculation hood of a heavy-duty UAV using the hot gas recirculation hood provided by the present invention. Figure 10 A schematic diagram of the overall structure of the hot air recirculation hood and the spoiler of the heavy-duty UAV using the recirculation hood provided by the present invention. Figure 11 A schematic diagram of the overall structure of the hot air recirculation hood and the side recirculation grille of the heavy-duty UAV using the recirculation hood provided by the present invention. Figure 12 A schematic diagram of the overall structure of the hot air recirculation hood and the active recirculation component of the heavy-duty UAV using the recirculation hood provided by the present invention. Attached image description: 10. Flight Department; 20. Power unit; 21. Mounting frame; 22. Fuel cell stack; 23. Hydrogen storage tank; 24. Radiator fan; 25. DC power unit; 30. Hot air recirculation hood; 31. Housing; 311. Rear cover; 312. Air inlet slot; 32. Fairing; 33. Spoiler; 331. Spoiler plate; 34. Side recirculation grille; 341. Grille plate; 35. Active recirculation assembly; 351. Recirculation bucket; 352. Valve plate; 353. Linear drive unit. Detailed Implementation

[0019] The following description is exemplary in nature and is not intended to limit the scope, application, or use of this disclosure. It should be understood that in all these figures, the same or similar reference numerals indicate the same or similar parts and features. The figures are merely schematic representations of the concept and principles of embodiments of this disclosure and do not necessarily show the specific dimensions and scale of the various embodiments of this disclosure. Certain details or structures of embodiments of this disclosure may be exaggerated in particular portions of certain figures.

[0020] Example 1, see Figures 1-11As shown, the hot gas recirculation hood and the heavy-duty UAV using the hood are designed to solve the problems of stable operation and efficient thermal management of hydrogen fuel cell systems in low temperature and low humidity environments. In this embodiment, the heavy-duty UAV adopts a hybrid power supply mode of hydrogen fuel cell and lithium battery, which has the potential for large payload and long endurance. The heavy-duty UAV includes a flight unit 10, a power unit 20, and a hot gas recirculation hood 30 installed on the power unit 20. The flight unit 10 is the flight execution mechanism of the UAV. It receives electrical energy provided by the power unit 20 and generates lift and thrust. The flight unit 10 includes a frame and rotor arms fixedly connected to the four corners of the frame. Each rotor arm is equipped with a rotor driven by a motor at its end. The detailed structure of the flight unit 10 can adopt the conventional design of multi-rotor UAVs, which will not be described in detail here.

[0021] The power unit 20 is the core of the UAV's energy and power conversion. It is fixedly installed under the frame of the flight unit 10 to supply power to the flight unit 10. The power unit 20 also serves as the mounting base for the hot gas return shroud 30. The hot gas return shroud 30 covers the outside of the fuel cell system stack 22 of the power unit 20, forming an adjustable local thermal environment cabin.

[0022] Specifically, the power unit 20 includes a landing gear 21, a fuel cell system stack 22, a hydrogen storage tank 23, and a cooling fan 24. The landing gear 21 is the main load-bearing and mounting frame, made of high-strength lightweight materials, such as aviation aluminum alloy 7075-T6. The upper part of the landing gear 21 is fixedly connected to the frame of the flight unit 10, and the lower part provides support during landing. The fuel cell system stack 22 and the hydrogen storage tank 23 are arranged on the side of the landing gear 21. The internal space of the landing gear 21 can be used to install lithium batteries to cooperate with the fuel cell system stack 22.

[0023] The fuel cell stack 22 is the main power generation device. In this embodiment, four proton exchange membrane fuel cell stack units are arranged in parallel. The rated power of each stack unit is not less than 4.6kW, and the total net output power of the system is greater than 16.5kW. The fuel cell stack 22 is fixed on the side frame of the mounting bracket 21. The cathode air inlet and anode hydrogen inlet of each fuel cell stack 22 are connected to the external air and hydrogen supply systems through pipelines, respectively. Hydrogen is supplied by the hydrogen storage tank 23 through a pressure reducing valve. The fuel cell stack 22 generates waste heat during operation. This waste heat is mainly dissipated through the heat dissipation surface of the stack itself and guided to a specific heat accumulation area. Specifically, heat pipes or heat spreaders can be installed on the side of each fuel cell stack 22 to conduct heat to a concentrated heat dissipation area, and then discharged by the cooling fan 24.

[0024] Specifically, the cooling fan 24 is an active cooling device, fixed on one side of the concentrated heat dissipation area of ​​the fuel cell system stack 22. The cooling fan 24 is preferably a high-volume axial fan, for example, with a size of 200mm×200mm×53mm and an operating voltage of 48V. Its function is to generate forced airflow to form negative pressure in the concentrated heat dissipation area, so that waste heat is discharged from the fuel cell system stack 22. The exhaust direction of the cooling fan 24 is towards a specific opening of the hot gas return shroud 30.

[0025] The hydrogen storage cylinder 23 is used to store high-pressure hydrogen. In this embodiment, the working pressure of the hydrogen storage cylinder 23 is 35MPa or 45MPa, and the volume is 12L. The hydrogen storage cylinder 23 is connected to the anode gas inlet system of the fuel cell stack 22 through a dedicated cylinder valve and high-pressure pipeline, and the hydrogen pressure is adjusted to the working pressure required by the stack through a pressure reducing valve.

[0026] Furthermore, the hot gas recirculation hood 30 includes a hood 31, a rectifier 32, a spoiler 33, a side recirculation grille 34, and an active recirculation assembly 35. The hood 31 is a hollow shell that is entirely covered outside the fuel cell system stack 22. The top of the hood 31 is fixedly and sealed to the upper surface of the fuel cell system stack 22, and the outer surface of the hood 31 is fixedly connected to the side of the mounting bracket 21. The inner wall of the casing 31 maintains a certain distance from the bottom, sides and rear of the fuel cell system stack 22, thereby forming an annular circulating air duct around the fuel cell system stack 22.

[0027] Furthermore, a rear cover 311 is fixedly connected to the rear part of the cover 31, that is, the side facing away from the exhaust direction of the cooling fan 24. The rear cover 311 is an inclined guide plate used to change the flow direction of the gas entering the cover 31 and guide the gas flow to converge in the middle of the cavity of the cover 31, that is, the area where the fuel cell system stack 22 is located.

[0028] Inside the housing 31, corresponding to the position of the cooling fan 24, a shroud 32 is fixedly installed. Its inlet is aligned with and sealed to the outlet of the cooling fan 24, while the outlet faces outward from the housing 31. The function of the shroud 32 is to confine the airflow from the cooling fan 24 to the outside of the housing 31, isolating it from the flow inside the housing 31, and forming a concentrated airflow that enters the spoiler 33. The spoiler 33 is fixedly installed on the surface of the housing 31. The spoiler 33 is in the shape of a convex semi-bowl, and its main function is to force the airflow from the shroud 32 to change direction and be discharged downward from the drone. For further details, please refer to [link / reference]. Figure 10 As shown, arc-shaped spoiler plates 331 are uniformly fixed on the inner wall of the spoiler 33, and the ends of multiple spoiler plates 331 converge toward the center of the spoiler 33 to promote concentrated exhaust of airflow.

[0029] The side return flow grille 34 is fixedly installed on the side wall of the housing 31. The side return flow grille 34 includes multiple parallel and inclined grille plates 341. All grille plates 341 are inclined in the same direction and are configured so that the inlet of their flow channel faces downward and the outlet faces the inside of the housing 31. External airflow must pass through the gap between the grille plates 341 from the downward direction to enter the inside of the housing 31. The purpose of this design is, on the one hand, to introduce external air into the housing to participate in circulation, and on the other hand, to use the inclined grille plates 341 to guide the airflow direction so that it can better merge with the original airflow in the housing after entering, forming a flow field that surrounds the fuel cell stack.

[0030] Furthermore, the bottom of the cover 31 is provided with multiple air inlets 312, which are the main channels for external air to enter the internal cavity of the cover 31 and are located at the lower part of the annular air duct; the active recirculation assembly 35 is an adjustable recirculation channel assembly used to regulate the internal thermal environment.

[0031] Specifically, the active reflux assembly 35 includes a reflux hopper 351, a valve plate 352, and a linear drive unit 353. The reflux hopper 351 is a bucket-shaped gas collection hood. The bottom of the reflux hopper 351 is fixedly connected to the valve plate 352. The reflux hopper 351 is slidably sealed to the cover 31. The surface of the valve plate 352 is provided with a through groove corresponding to the air inlet 312. One end of the linear drive unit 353 is fixed inside the housing 31, and the other end of the linear drive unit 353, i.e. the output end, is fixed on the valve plate 352. It is used to drive the return bucket 351 and the valve plate 352 to slide and adjust their positions, thereby controlling whether the exhaust gas discharged from the turbulence shroud 33 is introduced into the housing 31. On the other hand, it controls the overlap between the through groove and the air inlet 312, thereby controlling the external air intake volume.

[0032] When the linear drive unit 353 drives the return bucket 351 to retract, forming a seal with the cover 31, all the exhaust gas discharged by the cooling fan 24 is guided by the rectifier 32 and the spoiler 33 and then directly discharged to the bottom of the drone. The through slot and the air inlet 312 are completely overlapped to achieve maximum heat dissipation efficiency.

[0033] When waste heat needs to be introduced, the linear drive unit 353 drives the return bucket 351 to extend out of the cover 31, so that the top opening of the return bucket 351 corresponds to the bottom opening of the baffle 33. This allows the waste gas disturbed by the baffle 33 to be discharged into the cover 31 through the collection of the return bucket 351. At the same time, the overlap between the through slot and the air inlet slot 312 is reduced, that is, the valve plate 352 partially blocks the air inlet slot 312, reducing the external air intake. The proportion of external cold air entering from the bottom air inlet slot 312 and the side return grid 34 is relatively increased. The returned hot waste gas and the incoming external cold air mix in the cover 31, thereby increasing the overall temperature and humidity of the air surrounding the fuel cell system stack 22.

[0034] By controlling the extension distance of the return bucket 351 through the linear drive unit 353, the proportion of captured and returned hot waste gas can be adjusted, thereby achieving regulation of the internal microenvironment of the casing 31.

[0035] The linear drive unit 353 is a linear servo, voice coil motor, or servo electric cylinder.

[0036] Example 2, based on the above examples, in order to improve the ability of the hot gas return hood 30 to actively adapt to the surrounding environment, a DC electrical box 25 is also included. The DC electrical box 25 includes multiple step-down DC-DC converters, each of which is connected to the output terminal of a fuel cell system stack 22. It is used to step down and stabilize the unstable DC power output from the stack to a voltage that matches the power bus of the UAV. The DC electrical box 25 also includes a control unit, which is connected to a data acquisition unit. The data acquisition unit is used to collect operating condition data. Based on the operating condition data, the control unit generates control commands for the linear drive unit 353. The linear drive unit 353 receives control commands from the main control unit of the power unit 20 and controls the extension distance of the return bucket 351 to provide the best working environment for the fuel cell system stack 22 under different temperatures.

[0037] Specifically, the data acquisition unit includes multiple acquisition modules distributed on the UAV; the operating data includes the temperature and humidity inside and outside the housing 31, the outlet temperature of the fairing 32, and the real-time position of the return bucket 351. Specifically, the data acquisition module includes a first acquisition module, a second acquisition module, a third acquisition module, and a fourth acquisition module. The first and second acquisition modules are both temperature and humidity sensors, installed inside and outside the housing 31 respectively, and are used to acquire the internal temperature value, internal humidity value, ambient temperature value, and ambient humidity value, respectively labeled as follows: , , and ; The third data acquisition module is a temperature sensor, installed at the outlet of rectifier 32, used to collect the exhaust gas temperature value, marked as... ; The fourth acquisition module is a position sensor, integrated within the linear drive unit 353, used to provide feedback on the real-time position of the return bucket 351, marked as... .

[0038] The control method of the control unit is as follows: A person skilled in the art simulates different working environments and statistically analyzes the experimental data on range and load. The optimal operating temperature range and humidity range corresponding to the fuel cell system stack 22 are selected as the optimal operating temperature range and humidity upper limit, and these are used as control targets, respectively labeled as… and ; It periodically receives all sensor data, performs filtering processing, and then determines the working mode. like and When the mode is determined to be heat dissipation mode, the control unit controls the linear drive unit 353 to place the return bucket 351 in the retracted position; like or When the time is right, it is determined to be in moisturizing mode.

[0039] The method for controlling the moisturizing mode is as follows: calculate the temperature deviation. , ,in The target temperature value; The proportional-integral control algorithm is adopted, based on Calculate the position of the target reflux hopper 351 The calculation expression is: In the formula , The optimized parameters are obtained by experimentally calibrating a specific thermodynamic system consisting of a hot gas recirculation hood 30 and a fuel cell system stack 22. The calibration process can be determined by measuring the system's response to a temperature step signal in a simulated environment and using engineering tuning methods. monitor ,when Then for the calculated After applying negative correction, it serves as the adjustment parameter for the linear drive unit 353, driving the return bucket 351 to move to a designated position to prevent excessive humidity inside the cavity.

[0040] The exemplary implementation of the solution proposed in this disclosure has been described in detail above with reference to preferred embodiments. However, those skilled in the art will understand that various modifications and alterations can be made to the above specific embodiments without departing from the spirit of this disclosure, and various combinations can be made to the various technical features and structures proposed in this disclosure without exceeding the protection scope of this disclosure, which is determined by the appended claims.

Claims

1. A hot gas recirculation hood, comprising a hot gas recirculation hood (30), characterized in that: The hot gas recirculation hood (30) includes: The casing (31) is used to cover the outside of the fuel cell system stack (22), and the inside of the casing (31) and the fuel cell system stack (22) form an annular circulating air duct; The fairing (32) is used to vent the waste heat gas generated by the fuel cell system stack (22) to the outside of the casing (31); The spoiler (33) is located downstream of the exhaust path of the fairing (32) and is used to change the exhaust direction of the waste heat flow. An active recirculation assembly (35) is movably disposed on a housing (31) and has an exhaust gas capture section opposite to a spoiler (33); wherein the movement of the active recirculation assembly (35) is configured to synchronously adjust the proportion of exhaust gas recirculated to the housing (31) via the exhaust gas capture section and the flow rate of fresh air entering the housing (31) via the housing (31).

2. The hot gas recirculation hood according to claim 1, characterized in that, The rear of the cover (31) is provided with an inclined rear cover (311) for guiding airflow to converge in the middle.

3. The hot gas recirculation hood according to claim 1, characterized in that, The bottom of the cover (31) is provided with an air inlet (312) for external air to enter.

4. The hot gas recirculation hood according to claim 3, characterized in that, The active recirculation assembly (35) includes a recirculation bucket (351) as an exhaust gas capture unit, a valve plate (352) connected to the recirculation bucket (351), and a linear drive unit (353) that drives its movement. The return hopper (351) is slidably and sealed to the cover (31), and the valve plate (352) is used to adjust the opening area of ​​the air inlet slot (312).

5. The hot gas recirculation hood according to claim 4, characterized in that, The linear drive unit (353) may employ a linear actuator, including but not limited to a linear servo, a voice coil motor, or a servo electric cylinder.

6. The hot gas recirculation hood according to claim 1, characterized in that, The inner wall of the spoiler (33) is fixed with a plurality of arc-shaped spoiler plates (331) that converge toward the center of the spoiler (33).

7. The hot gas recirculation hood according to claim 1, characterized in that, The side of the cover (31) is fixed with a side return grid (34), which includes a plurality of inclined grid plates (341) with the inlet of the flow channel facing downwards.

8. The hot gas recirculation hood according to claim 1, characterized in that, It also includes a detection unit and a control unit; The detection unit is used to collect operating condition data of the hot gas recirculation hood and the fuel cell system stack; The control unit connects the detection unit and the active recirculation component, and is configured to generate control commands for the active recirculation component based on the operating condition data.

9. The hot gas recirculation hood according to claim 8, characterized in that, The control unit is configured to: When it is determined based on the operating condition data that enhanced heat dissipation is needed, the active recirculation component is controlled to move to the first position to minimize exhaust gas recirculation and maximize the intake of fresh air. When it is determined based on the operating data that heat preservation and humidification are required, the active recirculation component is controlled to move to a second position different from the first position, so as to introduce some exhaust gas recirculation and reduce the intake of fresh air.

10. A heavy-duty unmanned aerial vehicle (UAV) employing a fairing as described in any one of claims 1-9, characterized in that, It includes the flight section (10) and the power section (20); The power unit (20) includes a chassis (21), a fuel cell stack (22), a hydrogen storage tank (23) for supplying gas to the fuel cell stack (22), and a cooling fan (24) for dissipating heat from the fuel cell stack (22). The hot gas return shroud (30) is mounted on the machine stand (21) and covers the outside of the fuel cell system stack (22), and its shroud (32) is connected to the outlet of the cooling fan (24).

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