Multi-rotor air cooling hydrogen fuel cell unmanned aerial vehicle

Abstract

The invention relates to the technical field of unmanned aerial vehicles, and discloses a multi-rotor air cooling hydrogen fuel cell unmanned aerial vehicle. The air cooling hydrogen fuel cell system is innovatively designed to solve the problems that a lithium battery of a traditional unmanned aerial vehicle is low in energy density and short in endurance, and a system is complex and difficult to dissipate heat in hydrogen fuel cell application. The system comprises a hydrogen supply unit, a fuel cell stack unit, an air supply unit, a heat management unit and an electrical control unit, and can accurately regulate and control hydrogen supply, efficiently convert energy, intelligently dissipate heat and monitor in real time. Through long-endurance surveying and mapping and agricultural plant protection application, the endurance is greatly improved, and the application prospect is good.

Description

Technical Field

[0001] The present invention relates to the technical field of unmanned aerial vehicles, and particularly to a multi-rotor air-cooled hydrogen fuel cell unmanned aerial vehicle, and more particularly to an air-cooled hydrogen fuel cell system adopted by the unmanned aerial vehicle. Background Art

[0002] With the rapid development of unmanned aerial vehicle technology, it has been widely used in many fields such as aerial photography, logistics, surveying and mapping, and agriculture. However, traditional unmanned aerial vehicles mostly use lithium batteries as power sources. The energy density of lithium batteries is relatively low, resulting in limited endurance of unmanned aerial vehicles and inability to meet the requirements of some long-endurance and high-load application scenarios. Hydrogen fuel cells have the advantages of high energy density, clean environmental protection, and long endurance time, and have become an ideal power choice to improve the performance of unmanned aerial vehicles. However, the application of hydrogen fuel cells in unmanned aerial vehicles still faces many challenges, such as complex systems, difficult heat dissipation, large volume and weight, etc., which limit their further popularization and application. Summary of the Invention

[0003] The purpose of the present invention is to provide a multi-rotor air-cooled hydrogen fuel cell unmanned aerial vehicle, which effectively solves the problems of short endurance of unmanned aerial vehicles and complex hydrogen fuel cell systems in the prior art through an innovatively designed air-cooled hydrogen fuel cell system. The multi-rotor air-cooled hydrogen fuel cell unmanned aerial vehicle of the present invention mainly includes a fuselage, a multi-rotor power system, an air-cooled hydrogen fuel cell system, a control system and other parts. Among them, the air-cooled hydrogen fuel cell system is the core innovation point of the present invention. The air-cooled hydrogen fuel cell system mainly consists of a hydrogen supply unit, a fuel cell stack, an air supply unit, a thermal management unit and an electrical control unit. The hydrogen supply unit includes components such as a hydrogen cylinder, a pressure reducing valve, and a flow controller. The hydrogen cylinder stores high-pressure hydrogen, adjusts the hydrogen pressure to a suitable range through the pressure reducing valve, and then precisely controls the hydrogen flow by the flow controller to provide a stable hydrogen supply for the fuel cell stack. The fuel cell stack is the core component that converts the chemical energy of hydrogen and oxygen into electrical energy. The present invention adopts an advanced proton exchange membrane fuel cell stack, which has a high energy conversion efficiency and power density. The air supply unit includes an air filter, a fan and an air duct, etc. The air filter filters impurities in the air, the fan inhales external air, and transports the air to the fuel cell stack through the air duct to provide the oxygen required for the electrochemical reaction of the fuel cell stack. The thermal management unit is a key part to ensure the stable operation of the fuel cell stack. Since a large amount of heat is generated during the operation of the fuel cell stack, if the heat is not dissipated in time, it will seriously affect the performance and lifespan of the fuel cell stack. The present invention uses an air-cooling method for heat dissipation. By designing a reasonable heat dissipation air duct and heat sink, the heat generated by the fuel cell stack is carried away by the air flow. At the same time, the thermal management unit also includes a temperature sensor and a controller. The temperature sensor monitors the temperature of the fuel cell stack in real time. When the temperature is too high, the controller controls the fan to increase the rotation speed, increase the air flow, and enhance heat dissipation; when the temperature is too low, the controller controls the heating element to appropriately heat the fuel cell stack to ensure that the fuel cell stack always operates within the optimal working temperature range. The electrical control unit is responsible for monitoring and controlling the entire air-cooled hydrogen fuel cell system. It collects parameters such as hydrogen flow rate, air flow rate, output voltage and current of the fuel cell stack, and temperature in real time, and optimally controls the system based on these parameters to ensure the efficient and stable operation of the system. Description of the Drawings

[0004] Figure 1 This is a block diagram of a multi-rotor air-cooled hydrogen fuel cell unmanned aerial vehicle system according to the present invention. Detailed Implementation Modes

[0005] Example 1: A multi-rotor air-cooled hydrogen fuel cell unmanned aerial vehicle for long-duration mapping missions Raw material procurement and preparation: According to the design requirements, purchase large-capacity carbon fiber-wound hydrogen cylinders that meet the standards, ensuring that their manufacturers have corresponding qualifications and the products have passed strict inspections. High-precision proportional pressure reducing valves and mass flow controllers need to select well-known brands to ensure reliable performance. The proton exchange membrane fuel cell stack should be purchased with products certified for high energy conversion efficiency. Aluminum alloy materials are used to make the air ducts, and their material compositions need to be inspected to ensure compliance with the requirements of light weight and high strength.

[0006] Component installation and commissioning: Hydrogen supply unit: Install the hydrogen cylinder on a special fixing bracket on the fuselage. The fixing bracket is made of high-strength stainless steel and is firmly connected to the fuselage frame by bolts. Connect the pressure reducing valve and the flow controller, and use sealing tape to ensure good sealing at the connection. After installation, use a professional gas leakage detection instrument to comprehensively detect the entire hydrogen supply pipeline to ensure no leakage. Calibrate the pressure of the pressure reducing valve. Measure the output pressure with a standard pressure gauge and repeatedly adjust it to the 0.4 - 0.6 MPa range required by the fuel cell stack.

[0007] Fuel Cell Stack: Install a shock-absorbing bracket at the central position of the bottom of the fuselage. The bracket is made of a composite material of rubber and metal, which can effectively absorb flight vibrations. Place the fuel cell stack stably on the bracket and fix it with screws. Carefully check the electrical interface of the fuel cell stack to ensure that the connection plug is not damaged, and make the correct connection according to the positive and negative pole markings. After the connection is completed, use a multimeter to measure the conductivity of the electrical connection to ensure that the circuit is unobstructed.

[0008] Air Supply Unit: Install a high-efficiency paper filter at the air inlet of the fan. The filter is connected by snap fasteners for easy replacement. The fan is fixed to the preset position on the fuselage with bolts. Ensure the correct installation angle of the fan during installation to avoid uneven air flow caused by tilting. Connect the air duct and use sealant to seal the connection of the air duct. After the installation of the air duct is completed, use a fan performance test device to test the entire air supply system to ensure that the air flow reaches 100 m³ / h as required by the design, and at the same time detect the air pressure in the air duct to ensure compliance with the standard.

[0009] Thermal Management Unit: Install an annular heat dissipation air duct around the fuel cell stack. The heat dissipation air duct and the fuel cell stack are filled with thermal conductive silicone to enhance the heat conduction effect. Install copper heat sinks and use welding technology to ensure that the heat sinks are firmly connected to the air duct. Install high-precision thermistors in the heat-concentrated areas of the fuel cell stack, such as near the electrodes and on the surface of the membrane electrode assembly, and fix them with high-temperature resistant glue. Install a programmable logic controller (PLC) and connect the control lines of the temperature sensor, fan, and heating element. Program and debug the PLC, and set the temperature alarm threshold and the control logic of the fan and heating element.

[0010] Electrical Control Unit: Select a suitable position inside the fuselage to install an industrial-grade microcontroller and protect it with a metal shielding cover to reduce electromagnetic interference. According to the design drawings, reasonably arrange the wiring terminals of each sensor and actuator, and use wire troughs to organize the lines to ensure that the lines are neat and orderly. After connecting all the lines, conduct an electrical insulation test, and use an insulation resistance tester to measure the insulation resistance between each line and between the line and the fuselage to ensure compliance with safety standards.

[0011] Overall Machine Testing and Optimization: After the installation and commissioning of each component are completed, the overall performance of the drone is tested. The drone is placed on a professional flight test platform and connected to the ground control station. First, static testing is carried out to check whether the parameters of each system are normal, such as hydrogen flow rate, air flow rate, output voltage and current of the fuel cell stack, temperature, etc. Then, simulated flight testing is carried out. Instructions are sent through the ground control station to simulate the working conditions of the drone in different flight states, such as takeoff, hover, cruise, landing, etc. During the testing process, the operating status of each system is monitored in real time, and problems are optimized and adjusted in a timely manner. For example, if it is found that the temperature of the fuel cell stack is too high, the structure of the heat dissipation air duct can be further optimized or the speed control logic of the fan can be adjusted.

[0012] Practical Application and Effect Evaluation: The tested and optimized drone is put into long-endurance mapping tasks. In practical applications, parameters such as the flight time of the drone, the area of the mapping area, and the accuracy of data collection are recorded. It is compared with the same type of lithium battery mapping drone to evaluate the improvement effect of its endurance. Through practical application feedback, experience is continuously summarized, and the performance of the drone is continuously optimized, such as further optimizing the flow control accuracy of the hydrogen supply system and improving the energy conversion efficiency of the fuel cell stack.

[0013] Embodiment 2: A multi-rotor air-cooled hydrogen fuel cell drone for agricultural plant protection operations Raw Material Procurement and Preparation: Purchase medium-capacity aluminum alloy hydrogen cylinders and strictly inspect their pressure resistance performance and material quality. Select products with appropriate protection grades for the direct-acting pressure reducing valve and electromagnetic flow control valve for the agricultural operation environment. The miniaturized proton exchange membrane fuel cell stack needs to have good shock resistance and corrosion resistance. The waterproof and corrosion-resistant metal mesh filter and flexible rubber air duct material should ensure compliance with the special requirements of agricultural operations.

[0014] Component Installation and Commissioning: Hydrogen Supply Unit: Install the aluminum alloy hydrogen cylinder on the special fixing device of the fuselage. The fixing device is made of high-strength plastic and has a certain shock-absorbing function. Install the direct-acting pressure reducing valve and electromagnetic flow control valve, and use sealant to ensure the connection is sealed. Reinforce the fixing device of the hydrogen cylinder. By increasing the number of fixing bolts and using high-strength nuts, ensure the stability of the hydrogen cylinder during the frequent takeoff and landing of the drone. Conduct a pressure adjustment test on the pressure reducing valve, and use a pressure test instrument to adjust the output pressure to the range of 0.4 - 0.6 MPa.

[0015] Fuel cell stack: Install a high-strength plastic bracket on the side of the fuselage. The bracket is designed to match the shape of the fuel cell stack and is fixed with screws. Place the fuel cell stack on the bracket and fix it. Conduct special anti-corrosion coating treatment on the electrodes of the fuel cell stack, such as using electroless nickel plating process, to enhance the anti-pesticide corrosion ability of the electrodes. After the treatment, use a multimeter to check the electrical performance of the electrodes to ensure there is no abnormality.

[0016] Air supply unit: Install a waterproof and corrosion-resistant metal mesh filter at the air inlet of the axial flow fan and fix it by welding to ensure good sealing. The fan is installed at a suitable position on the fuselage through rubber shock pads to reduce the vibration transmission during the operation of the fan. Connect a flexible rubber air duct and fix the connection of the air duct with a clamp. After the installation is completed, conduct a waterproof test on the air supply unit. Place the whole unit in a simulated rainy environment and check whether there is water vapor entering inside after testing for a certain period of time.

[0017] Thermal management unit: Attach a flat heat dissipation air duct to the side of the fuel cell stack and fix it with thermal conductive glue. Install aluminum heat sinks and conduct anodizing treatment on the surface of the heat sinks to increase their corrosion resistance. Install thermocouple sensors and weld them at the key heat-generating parts of the fuel cell stack. Install a single-chip microcontroller and connect the control circuits of the temperature sensor, fan, and heating element. Program the single-chip microcontroller to set the temperature control threshold and the working logic of the fan and heating element.

[0018] Electrical control unit: Select a low-cost and high-performance microcontroller and install it in a sealed electrical control box. Connect each component with waterproof cables, and the connection heads of the cables use waterproof sealed connectors. Conduct a sealing treatment on the electrical control unit and fill the gaps of the control box with sealant. After the connection is completed, conduct an electrical performance test to check whether each control function is normal.

[0019] Overall machine test and optimization: Set up a temporary test site near the agricultural experimental field and place the UAV on the test stand. First, conduct a ground power-on test to check whether the initial state of each system is normal. Then conduct a low-altitude flight test, simulate the flight altitude and speed in the farmland environment, and observe the stability of the UAV and the working conditions of each system. During the test, monitor parameters such as the temperature, voltage, and current of the fuel cell system, as well as the flight attitude control of the UAV. If it is found that the UAV shakes or the temperature of the fuel cell stack is abnormal during the flight, stop the machine in time for inspection and optimization adjustment, such as adjusting the installation position of the fan or optimizing the control algorithm of the thermal management system.

[0020] Practical applications and effectiveness evaluation: The optimized drone is put into agricultural pest control operations. During the actual operation process, parameters such as the single operation time of the drone, the area of pesticide spraying, and the uniformity of pesticide spraying are recorded. It is compared with traditional fuel-powered pest control drones to evaluate its operation efficiency and environmental protection advantages. The usage feedback from farmers is collected, and according to the problems that occur in actual applications, such as the corrosion of components by pesticide residues and the flight stability of the drone under different terrain conditions, the drone is improved and optimized specifically, such as increasing the thickness of the protective coating or optimizing the flight control algorithm to adapt to complex terrains.

Claims

1. A multi-rotor air-cooled hydrogen fuel cell drone, characterized in that: It includes a fuselage, a multi-rotor power system, an air-cooled hydrogen fuel cell system and a control system. The air-cooled hydrogen fuel cell system includes: A hydrogen supply unit, comprising a hydrogen cylinder, a pressure reducing valve and a flow controller. The hydrogen cylinder is used to store high-pressure hydrogen. The pressure reducing valve is used to adjust the hydrogen pressure to a range suitable for the fuel cell stack. The flow controller is used to accurately control the hydrogen flow to stably supply hydrogen to the fuel cell stack. Fuel cell stacks, using advanced proton exchange membrane fuel cell stacks to convert the chemical energy of hydrogen and oxygen into electrical energy; An air supply unit, including an air filter, a fan and an air duct, wherein the air filter is used to filter impurities in the air, and the fan is used to inhale external air and transport the air to the fuel cell stack through the air duct to provide oxygen for the electrochemical reaction; The thermal management unit uses air flow to remove the heat generated by the fuel cell stack through the design of reasonable heat dissipation ducts and heat sinks. It is also equipped with a temperature sensor and a controller. The temperature sensor monitors the temperature of the fuel cell stack in real time. When the temperature is too high, the controller controls the fan to increase the speed to enhance heat dissipation. When the temperature is too low, the controller controls the heating element to heat the fuel cell stack. The electrical control unit is responsible for real-time collection of parameters such as hydrogen flow, air flow, fuel cell stack output voltage and current, temperature, etc., and optimizes and controls the entire air-cooled hydrogen fuel cell system based on these parameters.

2. The multi-rotor air-cooled hydrogen fuel cell drone according to claim 1, characterized in that: The hydrogen cylinder in the hydrogen supply unit is made of carbon fiber winding or aluminum alloy, and the fixing frame of the hydrogen cylinder is made of high-strength stainless steel or high-strength plastic, and is firmly connected to the fuselage frame by bolts or special fixing devices.

3. The multi-rotor air-cooled hydrogen fuel cell drone according to claim 1, characterized in that: The fuel cell stack is installed at the center of the bottom or on the side of the fuselage. When installed at the bottom, it is equipped with a shock-absorbing bracket. When installed on the side, the bracket is designed to match the shape of the fuel cell stack, and the electrodes of the fuel cell stack are treated with an anti-corrosion coating.

4. The multi-rotor air-cooled hydrogen fuel cell drone according to claim 1, characterized in that: The fan in the air supply unit is installed at a preset position of the fuselage through bolts or rubber shock-absorbing pads, the air duct is made of aluminum alloy or flexible rubber, and the air duct connection is sealed with sealant or clamps.

5. The multi-rotor air-cooled hydrogen fuel cell drone according to claim 1, characterized in that: The heat dissipation duct in the thermal management unit is installed in a ring or flat shape around the fuel cell stack. The heat sink is made of copper or aluminum and is connected to the duct by welding or thermal conductive adhesive. The temperature sensor is a high-precision thermistor or thermocouple and is installed in the heat concentrated area of ​​the fuel cell stack.

6. The multi-rotor air-cooled hydrogen fuel cell drone according to claim 1, characterized in that: The microcontroller in the electrical control unit is an industrial-grade or low-cost high-performance product, installed in a suitable position in the fuselage, and protected by a metal shielding cover or a sealed electrical control box. The wiring terminals of each sensor and actuator are arranged reasonably, the lines are organized using wire troughs, and electrical insulation tests are performed.

7. The multi-rotor air-cooled hydrogen fuel cell drone according to any one of claims 1 to 6, characterized in that: When the UAV is used for long-flight mapping missions, after completing the installation and debugging of various components, it is necessary to carry out static testing and simulated flight testing on a professional flight test platform, monitor the operating status of each system in real time through the ground control station, and continuously optimize the flow control accuracy of the hydrogen supply system and the energy conversion efficiency of the fuel cell stack based on actual application feedback.

8. The multi-rotor air-cooled hydrogen fuel cell drone according to any one of claims 1 to 6, characterized in that: When the UAV is used in agricultural plant protection operations, the hydrogen cylinder fixing device has a shock-absorbing function, the air supply unit has undergone a waterproof test, the heat sink surface of the thermal management unit is anodized, and the electrical control unit uses waterproof cables and sealed connectors. Improvements and optimizations have been made based on feedback from farmers for issues such as pesticide residue corrosion and flight stability in complex terrain.

Images