Parallel sealing and multi-stack integrated packaging structure of unmanned aerial vehicle fuel cell bipolar plate

Abstract

This invention discloses a parallel sealing and multi-stack integrated packaging structure for bipolar plates of a UAV fuel cell, including bipolar plates; several bipolar plates and membrane electrode assemblies (MEAs) are alternately stacked in a vertical direction, with a MEA and two parallel sealing components between adjacent bipolar plates; sealing grooves are formed on the outer periphery of the upper and lower surfaces of the bipolar plates, with a first limiting groove at the bottom of the groove; the parallel sealing component consists of a closed-loop sealing gasket and several through-embedded supporting sealing blocks, with a second limiting groove on one side of the closed-loop sealing gasket and a flat surface on the other side that fits against the membrane frame of the MEA to form a limiting constraint; the first and second limiting grooves align to form an adhesive limiting sealing cavity and are filled with adhesive limiting bodies; the bottom end cap integrates an air inlet and an air outlet, and together with the packaging shell and the top cap, forms an integrated insulating package. This invention integrates sealing, support, positioning, and limiting functions into one unit, effectively solving the problems of gasket slippage, creep, and MEA misalignment, and is suitable for the lightweight and extreme operating conditions of UAVs.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, specifically to a parallel sealing and multi-stack integrated packaging structure for bipolar plates of a UAV fuel cell. Background Technology

[0002] Hydrogen fuel cells, as a clean energy power generation device with high energy density, rapid recharging, and zero emissions, can significantly solve the industry pain points of short flight time and slow charging of drones compared to traditional lithium batteries. They have broad application prospects in various drone scenarios such as industrial inspection, logistics transportation, and surveying and exploration. However, in the engineering implementation of drone fuel cells, the reliability of bipolar plate sealing, the compactness of the fuel cell stack integration, and adaptability to operating environments are the core technological bottlenecks restricting their commercialization.

[0003] Current proton exchange membrane fuel cell stacks are assembled by alternating stacking of multiple bipolar plates and membrane electrode assemblies. The sealing structure between the bipolar plates is the core component to ensure the stack's airtightness, electrical insulation, and operational stability. Current mainstream sealing solutions and integrated packaging structures have the following technical defects: Insufficient sealing, anti-slip, and positioning performance, resulting in poor reliability: In traditional single-stack sealing solutions, the bipolar plate and the sealing gasket are only positioned by the fitting of the sealing groove. During the stacking and pressing process of UAVs, high-frequency vibration during flight, and high and low temperature thermal cycling conditions, the sealing gasket is prone to lateral slippage and local deformation. Furthermore, the lack of reliable bonding or mechanical locking structure between the sealing gasket and the bipolar plate leads to uneven contact pressure on the sealing surface, causing problems such as gas leakage and decreased electrical insulation performance. This makes it unsuitable for the extreme operating environment of UAVs with high altitude, low pressure, and strong vibration.

[0004] Separation of sealing and support structure design leads to insufficient assembly accuracy and lifespan: In existing solutions, the load-bearing support components and sealing gaskets of the fuel cell stack are mostly designed separately, requiring separate positioning during assembly, which is cumbersome and makes it difficult to guarantee positioning accuracy; at the same time, there is a lack of a precise control structure for the compression of the sealing gasket, which makes the sealing gasket prone to creep under long-term thermal and pressure cycling, resulting in continuous degradation of sealing performance and shortening the service life of the fuel cell stack.

[0005] Poor sealing compatibility of membrane electrode and difficulty in ensuring stack consistency: Regarding the sealing design of membrane electrode, the lack of coordinated positioning and adaptive sealing structure between the membrane frame and the sealing gasket of the framed membrane electrode makes it easy for problems such as cross-flow of anode and cathode media and misalignment of membrane electrode to occur. This leads to poor adhesion between membrane electrode and bipolar plate, poor performance consistency of individual cells, and insufficient stability of stack output power.

[0006] Low integration of multi-stack packaging makes it unsuitable for the lightweight requirements of drones: Existing fuel cell sealing and packaging solutions are mostly designed for ground vehicle scenarios and do not fully consider the core requirements of drones for extreme lightweighting and high power density; when multiple stacks are connected in parallel, there is a lack of unified packaging and fluid integration design, resulting in dispersed pipelines, complex assembly, serious redundancy in system volume and weight, and imperfect insulation protection design, which poses safety risks of high voltage leakage and short circuit.

[0007] Patent CN120356971A discloses a parallel sealing device and method for fuel cell bipolar plates. This solution embeds multiple sets of support blocks throughout the sealing gasket, forming a sealing frame structure. The first bipolar plate and one or more second bipolar plates are aligned and stacked through this sealing frame, enabling multiple stacks to be connected in parallel. This solution solves, to some extent, the problems of sealing gasket positioning and multi-stack integration, improving the vibration and shock resistance of the fuel cell stack.

[0008] However, the above solutions are mainly aimed at fuel cells for ground vehicles and do not fully consider the special requirements of drone application scenarios, such as extreme lightweighting and adaptability to high-altitude and low-pressure environments. Summary of the Invention

[0009] This invention provides a parallel sealing and multi-stack integrated packaging structure for bipolar plates of a UAV fuel cell. The invention provides the following technical solution, including: bipolar plates, membrane electrode assemblies (MEAs), parallel sealing components, membrane frame, sealing groove, first limiting groove, gas channel unit groove, titanium alloy tie rod, tie rod hole, positive current collector, negative current collector, insulating plate, top cover, bottom cover, air inlet, air outlet, packaging shell, top cover, external terminal, and tie rod nut. A plurality of bipolar plates and a plurality of MEAs are stacked vertically. Between two adjacent bipolar plates, one MEA and two parallel sealing components are provided. Each MEA is provided with a membrane frame, which is clamped between two parallel sealing components to form a planar limiting constraint on the MEA. The inner contour of the parallel sealing component matches the outer contour of the membrane frame. Each bipolar plate has a sealing groove on its upper and lower outer periphery, and the bottom of the sealing groove has the first limiting groove. Preferably, each of the bipolar plates and the top cover has four gas channel unit slots through it, and each bipolar plate has a rod hole through it that allows the titanium alloy rod to pass through. At least four titanium alloy rods are provided. The upper end of each titanium alloy rod is screwed with a rod nut, and the lower end of each titanium alloy rod is fixedly installed on the bottom cover. Preferably, the lower surface of the lowest bipolar plate of the fuel cell is provided with the positive current collector, which is fixedly installed on the upper surface of the bottom end cover, with an insulating plate installed between them. The upper surface of the uppermost bipolar plate of the fuel cell is provided with the negative current collector, which is fixedly connected to the lower surface of the top end cover, with an insulating plate installed between them. The bottom end cover has an air inlet and an air outlet that communicate with the gas channel unit slot. An encapsulation shell is installed on the bottom end cover, and a top cover is fixedly installed in the opening above the encapsulation shell. The external terminals of the positive and negative electrodes are insulated and fixedly inserted into the encapsulation shell and connected to the corresponding positive or negative current collector.

[0010] Preferably, two adjacent bipolar plates, one membrane electrode, and two parallel sealing elements of the plates constitute a single battery cell unit. Multiple single battery cells are electrically connected in series to form a single stack module. Multiple single stack modules are connected in parallel to form a fuel cell system. The fuel cell is encapsulated inside the bottom end cover, the encapsulation shell, and the top cover, which together form an encapsulation and sealing structure.

[0011] Preferably, the sealing grooves formed on the outer periphery of the upper and lower surfaces of the bipolar plate are closed-loop rectangular grooves, and the bottom of the sealing groove is provided with a first limiting groove of the closed-loop rectangle along the same contour. The sealing grooves are assembled together with the corresponding electrode plate parallel sealing components.

[0012] Preferably, the parallel sealing element of the bipolar plates includes a closed-loop sealing gasket, a supporting sealing block, and a second limiting groove. A plurality of the supporting sealing blocks are evenly embedded in the closed-loop sealing gasket to form a through-type integrated structure. The end face of the supporting sealing block is flush with the upper and lower surfaces of the closed-loop sealing gasket. The second limiting groove is formed on one surface of the closed-loop sealing gasket. The closed-loop sealing gasket is assembled in the sealing groove corresponding to the bipolar plate.

[0013] Preferably, the closed-loop sealing gasket is a rectangular sealing gasket structure, the surface of the closed-loop sealing gasket with the second limiting groove is fitted into the sealing groove, the other side surface of the closed-loop sealing gasket is a plane, and the plane of the closed-loop sealing gasket is in contact with the surface of the membrane frame where the membrane electrode is disposed.

[0014] Preferably, the second limiting groove of the closed-loop sealing gasket corresponds to the first limiting groove of the bottom of the sealing groove, wherein the second limiting groove and the first limiting groove form an adhesive limiting sealing cavity, and the colloid solidifies in the adhesive limiting sealing cavity to form an adhesive limiting body.

[0015] Preferably, the bottom cover, the outer casing, and the top cover are all encapsulation structures made of insulating material. The lower opening of the outer casing is encapsulated by the bottom cover, and its upper opening is encapsulated by the rectangular top cover. A sealing gasket is installed between the outer casing and the bottom cover and the top cover. The bottom cover and the top cover are fixedly connected to the outer casing by bolts.

[0016] Preferably, the gas channel unit slots of the bipolar plates correspond to each other and are located on the same vertical line. The gas channel unit slots and the airflow pipes in the bipolar plates form two gas flow channel units. The two airflow channel units are respectively connected to the air inlet and air outlet of the bottom end cover. The bipolar plates have air inlets that communicate with the gas channel unit slots. The gas channel unit slots are connected to the airflow pipes in the bipolar plates through the air inlets. The air inlets and air outlets are respectively connected to the hydrogen inlet pipe, the air inlet pipe, and the corresponding exhaust pipe through manifolds.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention forms an adhesive limiting sealing cavity by aligning the first limiting groove at the bottom of the bipolar plate sealing groove and the second limiting groove on the surface of the closed-loop sealing gasket. After the colloid cures, it forms an adhesive limiting body, achieving precise bonding and fixation and secondary limiting between the sealing gasket and the bipolar plate. This significantly solves the problems of lateral slippage and misalignment of the sealing gasket during stacking assembly, flight vibration, and high and low temperature thermal cycling, ensuring uniform contact pressure on the sealing surface throughout the circumference, effectively preventing gas leakage, and significantly improving the long-term sealing stability of UAVs under high-altitude low-pressure and strong vibration conditions.

[0018] 2. This invention adopts an integrated electrode plate parallel sealing component with a closed-loop sealing gasket and an embedded supporting sealing block. The end face of the supporting sealing block is flush with the surface of the sealing gasket. During stacking and pressing, the maximum compression of the sealing gasket is precisely limited by the rigid supporting sealing block, which effectively avoids creep failure caused by over-compression of the sealing gasket, while ensuring that the compression rate of the sealing gaskets in all layers of the stack is uniform. The integrated structure combines sealing, support and positioning functions, which greatly reduces the number of assembly parts and processes, and improves positioning accuracy and mass production efficiency.

[0019] 3. In this invention, the membrane frame of the membrane electrode is sandwiched between the flat mating surfaces of the parallel sealing components of the upper and lower plates. Axial compression forms a uniform surface pressure seal, avoiding the destruction of the sealing surface integrity by slotting and effectively preventing the risk of cross-contamination between the anode and cathode media. At the same time, the inner ring contour of the parallel sealing components of the plates forms a precise planar limiting constraint on the membrane frame, preventing the membrane electrode from shifting or misaligning. This ensures that the membrane electrode and the bipolar plate flow field reaction zone are tightly fitted without gaps, significantly improving the performance consistency of each individual cell and the stability of the stack output power.

[0020] 4. This invention forms an integrated insulating encapsulation structure through a bottom end cover, an encapsulation shell, and a top cover. The air inlet and outlet are integrated into the bottom end cover, forming a unified airflow channel unit with the gas channel unit slot of the bipolar plate. This eliminates the need for dispersed external piping, significantly reducing system volume and weight, and increasing volumetric power density. An insulating plate is added between the current collector and the end cover, and the external terminals are insulated and fixed to the encapsulation shell, improving the insulation protection design and effectively avoiding the risks of high-voltage leakage and short circuits. This fully meets the core requirements of UAVs for lightweight, highly integrated, and highly safe fuel cells.

[0021] 5. This invention enables flexible parallel integration of multiple battery stacks through standardized single battery cells. The unified packaging structure and fluid channel design solve the problems of complex assembly and volume redundancy in traditional multi-stack integration. The number of parallel units can be flexibly adjusted according to the power requirements of the UAV. The modular design enables good interchangeability of each component, greatly reducing maintenance and operation costs. Attached Figure Description

[0022] Figure 1 This is a partial cross-sectional structural diagram of the entire invention.

[0023] Figure 2 This is the present invention. Figure 1 Another perspective structural diagram.

[0024] Figure 3 This is the present invention. Figure 1 A magnified schematic diagram of the structure at point A.

[0025] Figure 4 This is a half-sectional structural diagram of the single battery cell of the present invention.

[0026] Figure 5 This is the present invention. Figure 4 A magnified schematic diagram of the structure at point B.

[0027] Figure 6 This is a schematic diagram of the bipolar plate of the present invention.

[0028] Figure 7 This is a partial cross-sectional structural diagram of the parallel sealing element of the electrode plates of the present invention.

[0029] Figure 8 This is a schematic diagram of the structure of the present invention without the outer casing installed.

[0030] In the picture: 1. Bipolar plate, 2. Membrane electrode, 3. Parallel sealing element of electrode plate, 31. Closed-loop sealing gasket, 32. Support sealing block, 33. Second limiting groove, 4. Membrane frame, 5. Sealing groove, 6. First limiting groove, 7. Gas channel unit groove, 8. Titanium alloy pull rod, 9. Pull rod hole, 10. Positive current collector, 11. Negative current collector, 12. Insulating plate, 13. Top cover, 14. Bottom cover, 15. Air inlet, 16. Air outlet, 17. Encapsulation shell, 18. Top cover, 19. External terminal, 20. Pull rod nut. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0032] As attached Figure 1-8 As shown: This invention provides a parallel sealing and multi-stack integrated packaging structure for bipolar plates of a UAV fuel cell, comprising a bipolar plate 1, a membrane electrode 2, a parallel sealing element 3, a membrane frame 4, a sealing groove 5, a first limiting groove 6, a gas channel unit groove 7, a titanium alloy pull rod 8, a pull rod hole 9, a positive current collector 10, a negative current collector 11, an insulating plate 12, a top cover 13, a bottom cover 14, an air inlet 15, an air outlet 16, a packaging shell 17, a top cover 18, an external terminal 19, and a pull rod nut 20. A plurality of bipolar plates 1 and a plurality of membrane electrodes 2 are stacked vertically. Between two adjacent bipolar plates 1, one membrane electrode 2 and two parallel sealing elements 3 are provided. Each membrane electrode 2 is provided with a membrane frame 4, which is clamped between two parallel sealing elements 3. Each bipolar plate 1 has a sealing groove 5 on its upper and lower outer peripheries, and the bottom of the sealing groove 5 is provided with the first limiting groove 6.

[0033] Specifically, four gas channel unit slots 7 are coaxially formed on each bipolar plate 1 and the top cover 13. The bipolar plate 1 is precision stamped from a 0.1mm thick titanium alloy sheet, and a PVD nano-carbon coating with a thickness of <100nm is deposited on the surface. The cathodic corrosion current is <8×10 -7 A / cm 2 Contact resistance <7mΩ·cm 2The gas channel unit slots 7 are evenly distributed along the rectangular outline corners of the bipolar plate 1 and are connected to the reaction medium flow channels inside the bipolar plate 1. A tie rod hole 9, allowing the titanium alloy tie rod 8 to pass through, is also coaxially opened at the rectangular outline corners of the bipolar plate 1. The tie rod hole 9 is staggered with the gas channel unit slots 7 to avoid flow channel interference. At least four titanium alloy tie rods 8 are provided, made of TC4 aerospace-grade titanium alloy, and conform to the M8 standard. The upper end of the titanium alloy tie rod 8 is machined with external threads and fitted with a tie rod nut 20. The lower end of the titanium alloy tie rod 8 is fixedly installed in the corresponding mounting hole of the bottom cover 14 by pre-embedding and threaded locking. The axes of all titanium alloy tie rods 8 are parallel to each other and perpendicular to the stacking plane of the bipolar plates 1 to ensure the coaxiality and uniformity of the clamping force of each bipolar plate 1 during stacking.

[0034] Specifically, a positive current collector 10 is tightly fitted onto the lower surface of the bottom bipolar plate 1 of the fuel cell stack structure. The positive current collector 10 is made of oxygen-free copper with a gold-plated surface and is used to collect the total positive current of the stack structure. The positive current collector 10 is fixedly installed on the upper surface of the bottom end cover 14, and an insulating plate 12 is installed between the positive current collector 10 and the bottom end cover 14. The insulating plate 12 is made of high-insulation-strength polyimide (PI) or epoxy resin with an electrical insulation strength ≥20kV / mm, achieving insulation isolation between the charged current collector and the external end cover. A negative current collector 11 is tightly fitted onto the upper surface of the top bipolar plate 1 of the fuel cell stack structure. The negative current collector 11 is made of the same material as the positive current collector 10. The negative electrode current collector 11 is fixedly connected to the lower surface of the top cover 13, and an insulating plate 12 is also installed between the negative electrode current collector 11 and the top cover 13. The bottom cover 14 has an air inlet 15 and an air outlet 16 that are coaxially connected and correspond to the gas channel unit slot 7. The upper surface edge of the bottom cover 14 is positioned and installed with a sealing shell 17. An external terminal 19 is fixedly installed at the upper opening of the sealing shell 17. The two sets of external terminals 19 for positive and negative electrodes are inserted into the inside of the sealing shell 17 with a sealed insulating structure, and are reliably electrically connected to the corresponding positive electrode current collector 10 and negative electrode current collector 11 through flexible copper busbars to realize the external output of fuel cell power.

[0035] Specifically, two adjacent bipolar plates 1, one membrane electrode 2, and two parallel sealing elements 3 together constitute an independent single-cell battery unit. The membrane electrode 2 is a five-in-one proton exchange membrane MEA module with a membrane frame 4, including a proton exchange membrane, two catalytic layers, two gas diffusion layers, and an outer insulating membrane frame 4. The two parallel sealing elements 3 are respectively attached to the upper and lower sides of the membrane electrode 2, and are sandwiched between the two bipolar plates 1, forming a configuration of "bipolar plate 1 - parallel sealing element 3 - membrane electrode 2 - parallel sealing element 3 - bipolar plate 1". The standard stacking hierarchy is as follows: multiple individual battery cells are stacked sequentially along a direction perpendicular to the plane of the bipolar plate 1, and are electrically connected in series by sharing the middle bipolar plate 1 between adjacent cells to form a single stack module. Multiple single stack modules can be electrically connected in parallel to form a high-power fuel cell system according to power requirements. The complete fuel cell system is encapsulated inside the cavity formed by the bottom end cover 14, the encapsulation shell 17 and the top cover 18. The three are sealed together to form a dustproof and waterproof encapsulation and sealing structure, which is suitable for the complex working conditions of drone outdoor flight and high-altitude low-pressure.

[0036] Specifically, the outer sealing areas of the upper and lower surfaces of the bipolar plate 1 are provided with closed-loop rectangular sealing grooves 5. The contour of the sealing grooves 5 is equidistantly set along the outer contour of the bipolar plate 1, and is precisely matched with the outer dimensions of the parallel sealing component 3 of the electrode plate. The depth of the sealing grooves 5 is 0.3-1.0mm, the width is 2.5mm, and the cross-section is rectangular. At the center of the bottom wall of the sealing groove 5, a closed-loop rectangular first limiting groove 6 is provided along the same contour of the sealing groove 5. The depth of the first limiting groove 6 is 0.1-0.5mm, the width is 1.0mm, and it is fully connected to the sealing groove 5. The sealing grooves 5 and the corresponding parallel sealing components 3 of the electrode plate are assembled with a clearance fit, with a fit tolerance of H7 / h6, to ensure the assembly positioning accuracy and sealing fit effect.

[0037] Specifically, the parallel sealing component 3 of the electrode plates is an integrated structure, including a closed-loop sealing gasket 31, supporting sealing blocks 32, and a second limiting groove 33. Several supporting sealing blocks 32 are evenly distributed circumferentially and embedded throughout the body of the closed-loop sealing gasket 31, forming a through-type integrated structure with the closed-loop sealing gasket 31 through a molding and vulcanization process. The number of supporting sealing blocks 32 is 4-12, which can be adjusted according to the fuel cell stack specifications. The supporting sealing blocks 32 are made of carbon fiber reinforced PEEK composite material with a density of approximately 1.42 g / cm³. 3The compressive strength is ≥180MPa, and the electrical insulation strength is ≥20kV / mm. Its upper and lower end faces are flush with the upper and lower surfaces of the closed-loop sealing gasket 31, without any protrusions or depressions. When stacked and pressed, the supporting sealing block 32 bears the axial pressing force, and the closed-loop sealing gasket 31 bears the sealing function. The surface of the closed-loop sealing gasket 31 facing the sealing groove 5 of the bipolar plate 1 has a second limiting groove 33 that is precisely aligned with the first limiting groove 6. The closed-loop sealing gasket 31 is embedded and assembled in the corresponding sealing groove 5 of the bipolar plate 1, realizing the four functions of sealing, support, positioning and limiting in one.

[0038] Specifically, the closed-loop sealing gasket 31 is a rectangular closed-loop sealing gasket structure that matches the contour of the sealing area of ​​the bipolar plate 1. It is made of fluororubber FKM material with a density of approximately 1.85 g / cm³. 3 The operating temperature range is -40℃ to 250℃, the electrical insulation strength is ≥15kV / mm, and the compression set (100℃×70h) is ≤12%. The closed-loop sealing gasket 31 has a surface with a second limiting groove 33, which is embedded and assembled towards the bottom of the sealing groove 5 of the bipolar plate 1. The other side surface of the closed-loop sealing gasket 31 is a complete smooth plane without grooves or protrusions. The smooth plane of the closed-loop sealing gasket 31 is in close contact with the surface of the membrane frame 4 fixedly set around the membrane electrode 2. The inner ring contour of the closed-loop sealing gasket 31 is precisely matched with the outer ring contour of the membrane frame 4. The inner ring sidewall forms a planar limiting constraint on the membrane frame 4. During stacking and pressing, the smooth plane of the closed-loop sealing gasket 31 forms a uniform axial clamping surface pressure on the membrane frame 4, realizing the surface sealing of the edge of the membrane electrode 2 and avoiding cross-contamination of the anode and cathode reaction media.

[0039] Specifically, the second limiting groove 33 on the closed-loop sealing gasket 31 and the first limiting groove 6 at the bottom of the sealing groove 5 of the bipolar plate 1 are precisely aligned after assembly, and the two enclose a closed-loop rectangular adhesive limiting sealing cavity. The adhesive limiting sealing cavity is filled with a fluid colloid, which completely cures at room temperature to form an adhesive limiting body. The colloid is Dow Corning 737 fluorosilicone sealant, but epoxy resin sealant, polyurethane sealant, and other suitable materials can also be used. The cured adhesive limiting body forms a firm bond with the bipolar plate 1 and the closed-loop sealing gasket 31, achieving precise positioning of the sealing gasket and the bipolar plate, lateral anti-slip, and secondary auxiliary sealing, significantly suppressing the problem of misalignment and deformation of the sealing gasket under stacked assembly and vibration conditions.

[0040] Specifically, the bottom cover 14, the encapsulation shell 17, and the top cover 18 are all made of high-insulation-strength, lightweight, and high-strength insulating materials, with carbon fiber composite materials being the preferred choice. Glass fiber reinforced epoxy resin, PPS, and other engineering plastics can also be used to meet the extreme lightweight requirements of drones. The encapsulation shell 17 is a vertically continuous rectangular cylindrical structure. Its lower opening is positioned and sealed with the bottom cover 14 via a stop, and its upper opening is positioned and sealed with the rectangular top cover 18 via a stop. A closed-loop sealing gasket 31 rings are installed between the mating stop surfaces of the encapsulation shell 17, the bottom cover 14, and the top cover 18. These 31 rings are made of silicone rubber to ensure the airtightness and insulation of the encapsulation cavity. The bottom cover 14 and the top cover 18 are both locked and fixed to the upper and lower end faces of the encapsulation shell 17 by circumferentially evenly arranged stainless steel bolts, forming a stable overall encapsulation structure.

[0041] Specifically, after the stacking assembly is completed, all the gas channel unit slots 7 opened on the bipolar plates 1 are corresponding and their axes are on the same vertical line, forming two sets of independent medium channels that run through the stack axis. The multiple sets of coaxially connected gas channel unit slots 7, together with the airflow pipes opened inside the bipolar plates 1, form two independent gas flow channel units. One airflow channel unit is a hydrogen inlet channel, and the other is a reaction tail gas exhaust channel. The bottom ends of the two airflow channel units correspond to and are sealed and connected to the air inlet 15 and air outlet 16 provided on the bottom end cover 14, respectively. The flow field area of ​​the bipolar plates 1 is provided with a branch gas port that communicates with the gas channel unit slots 7. The gas channel unit slots 7 are connected to the airflow pipes and flow field reaction area inside the bipolar plates 1 through the branch gas port, so as to realize the uniform distribution of the reaction medium to each single cell unit. The air inlet 15 and the air outlet 16 are sealed and connected to the external hydrogen inlet pipe and the tail gas exhaust pipe, respectively, through a compression fitting insulated manifold, so as to realize the unified supply and discharge of the medium of the fuel cell system. Example

[0042] This embodiment is completely consistent with Embodiment 1 in its core structural system, material selection standards, sealing and anti-slip design principles, and multi-stack integrated packaging logic. The core innovative "sealing-support-positioning-limiting four-function integrated" design system is fully retained. Only for the low-power, ultra-lightweight, and small installation space requirements of small industrial inspection and surveying drones, the core parameters of the fuel cell stack, sealing frame layout, and packaging specifications have been adapted and optimized. The specific differentiated designs are as follows: Specifically, this embodiment addresses the power requirements of small unmanned aerial vehicles (UAVs). The fuel cell stack is designed with a rated power of 3kW and consists of 50 individual cells connected in series. The core components of each individual cell are completely identical to those in Embodiment 1, including one five-in-one proton exchange membrane (MEA) module with a membrane frame and two metal bipolar plates. The bipolar plates are still precision-stamped from 0.1mm thick titanium alloy sheets, with a PVD nano-carbon coating of <100nm thickness deposited on the surface, and a cathodic corrosion current of <8×10⁻⁶. -7 A / cm 2 Contact resistance <7mΩ·cm 2 The effective reaction area is proportionally adapted to the power requirement, and the core corrosion resistance and conductivity indicators remain consistent with those of Example 1.

[0043] Specifically, the parallel sealing element 3 used in this embodiment is the core of this invention, an integrated structure of "sealing-supporting-positioning-limiting" four functions. The overall size of the parallel sealing element 3 is proportionally reduced to the contour of the sealing area of ​​the bipolar plate 1, adapting to the assembly requirements of a 3kW fuel cell stack. Unlike the layout of 18 supporting sealing blocks 32 in embodiment 1, in this embodiment, only 4 cylindrical supporting sealing blocks 32 are uniformly embedded in the circumference of each parallel sealing element 3. The supporting sealing blocks 32 are still made of carbon fiber reinforced PEEK composite material, and their upper and lower end faces are completely flush with the upper and lower surfaces of the closed-loop sealing gasket 31. During stacking and pressing, the rigid supporting sealing blocks 32 bear the axial compression force, precisely limiting the maximum compression of the closed-loop sealing gasket 31 and ensuring uniform pressure on the sealing surfaces of all layers of the stack. The closed-loop sealing gasket 31 is still made of fluororubber (FKM) material, and its core performance indicators are completely consistent with those of embodiment 1, making it suitable for high-frequency vibration and high and low temperature thermal cycling conditions during the flight of small UAVs.

[0044] Specifically, the sealing interface and anti-slip structure of this embodiment are completely consistent with the principle of the bipolar plate sealing interface and anti-slip composite sealing structure in embodiment 1: A rectangular closed-loop sealing groove 5 is formed on the outer periphery of the sealing surface of the bipolar plate 1. A first limiting groove 6 is formed at the center of the bottom of the sealing groove 5 with the same contour. A second limiting groove 33 is formed on the surface of the closed-loop sealing gasket 31 facing the bottom of the sealing groove 5, which is precisely aligned with the first limiting groove 6. The two are joined to form an adhesive limiting sealing cavity, which is filled with Dow Corning 737 fluorosilicone sealant. After curing at room temperature, it forms an adhesive limiting body, realizing the precise bonding and fixation of the sealing gasket and the bipolar plate 1 and the lateral anti-slip constraint. Only the overall contour of the sealing groove 5 and the limiting groove is reduced proportionally with the size of the sealing frame. The core size tolerance and assembly process are consistent with embodiment 1, ensuring the sealing reliability in miniaturized scenarios.

[0045] Specifically, the packaging structure is designed to be extremely miniaturized. The packaging shell 17 in this embodiment is made of carbon fiber composite material and molded in one piece. The external dimensions are optimized to 220mm×200mm×150mm. Compared with the multi-stack integrated packaging structure in high-power scenarios, the overall size is greatly reduced, which can perfectly fit the narrow cabin installation space of small drones.

[0046] Specifically, after optimization, the lightweight performance and scenario adaptability advantages of this embodiment are such that the weight of the 3kW single-stack unit is ≤4.5kg and the power density is ≥650W / kg. Compared with the high-power stack of Embodiment 1, it further achieves extreme lightweighting, perfectly meeting the core requirements of small UAVs for high power density, small size and light weight of the power system. At the same time, it fully retains the core advantages of high sealing reliability, strong vibration resistance and long service life of Embodiment 1, and can stably adapt to the long-term continuous flight conditions of small UAVs in scenarios such as low-altitude inspection and aerial surveying.

[0047] First, the stack assembly and axial pre-tightening positioning are completed: the individual battery cells are stacked sequentially according to the standard hierarchy of "bipolar plate 1 - parallel plate seal 3 - membrane electrode 2 - parallel plate seal 3 - bipolar plate 1". The titanium alloy tie rod 8 is passed through the tie rod hole 9 of the bipolar plate 1, and the lower end is fixed to the bottom end cover 14. The upper end is subjected to uniform axial pre-tightening force through the tie rod nut 20. During the pre-tightening process, the support sealing block 32 in the parallel plate seal 3 rigidly bears the force, accurately limiting the compression of the closed-loop sealing gasket 31, ensuring uniform pressure on the sealing surfaces of each layer of the stack. At the same time, the parallelism constraint of the titanium alloy tie rod 8 ensures the coaxiality of each bipolar plate 1.

[0048] Secondly, the sealing interface locking and anti-slip limiting are completed: Before stacking and assembling, sealing colloid is injected into the first limiting groove 6 of the sealing groove 5 of the bipolar plate 1, and the closed-loop sealing gasket 31 is embedded into the sealing groove 5, so that the second limiting groove 33 is precisely aligned with the first limiting groove 6. The colloid cures to form an adhesive limiting body, which firmly bonds the closed-loop sealing gasket 31 to the bipolar plate 1, forming a double sealing barrier and lateral anti-slip constraint. At the same time, the inner ring contour of the closed-loop sealing gasket 31 forms a planar limiting on the membrane frame 4 of the membrane electrode 2, and the axial pre-tightening force makes the closed-loop sealing gasket 31 form a uniform clamping surface pressure on the membrane frame 4, realizing the surface sealing of the edge of the membrane electrode 2 and avoiding cross-contamination of the anode and cathode reaction media.

[0049] Next, the integrated and uniform distribution of the reaction medium is completed: hydrogen and reaction air enter from the air inlet 15 of the bottom cover 14, and are evenly distributed to the flow field reaction zone of each single cell through the axial airflow channel unit formed by the coaxial gas channel unit 7 and the gas distribution port of the bipolar plate 1, so as to continuously supply the reaction medium for the electrochemical reaction of the membrane electrode 2; the exhaust gas after the reaction is collected in the axial airflow channel unit through the bipolar plate 1 channel, and finally discharged uniformly from the air outlet 16 of the bottom cover 14, realizing the centralized supply and discharge of the medium.

[0050] Subsequently, the electrochemical reaction and concentrated output of electrical energy are completed: the hydrogen and air supplied to the membrane electrode 2 undergo redox electrochemical reactions in the catalytic layers on both sides of the proton exchange membrane. The generated electrons are conducted through the bipolar plate 1 and gradually collected through the series structure between the monomers. Finally, they are collected by the positive current collector 10 and negative current collector 11 at the beginning and end of the stacked structure. The electrical energy is output to the outside through the external terminal 19 connected to the current collector to provide power for the drone.

[0051] Finally, multi-stack integration and operating condition adaptation are achieved: multiple assembled single-stack modules can be electrically connected in parallel to form a high-power fuel cell system according to the power requirements of the UAV. All single stacks share a unified fluid manifold interface within the encapsulation shell 17, which significantly reduces the system volume and weight. The lightweight and insulated encapsulation structure and integrated sealing design can adapt to the complex operating conditions of UAVs, such as high altitude, low pressure, strong vibration, and wide temperature variation. At the same time, the spacing effect of the supporting sealing block 32 suppresses the creep failure of the closed-loop sealing gasket 31 under long-term thermal and pressure cycling, ensuring the sealing reliability and performance stability of the fuel cell stack during long-term operation.

[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A parallel sealing and multi-stack integrated packaging structure for bipolar plates of a UAV fuel cell, characterized in that: The bipolar plates (1), membrane electrodes (2), parallel sealing elements (3), membrane frame (4), sealing groove (5), first limiting groove (6), gas channel unit groove (7), titanium alloy pull rod (8), pull rod hole (9), positive current collector (10), negative current collector (11), insulating plate (12), top cover (13), bottom cover (14), air inlet (15), air outlet (16), encapsulation shell (17), top cover (18), external terminal (19), and pull rod nut (20) are stacked vertically. The bipolar plates (1) are stacked together, with a membrane electrode (2) and two parallel sealing members (3) between two adjacent bipolar plates (1). Each membrane electrode (2) is provided with a membrane frame (4), which is sandwiched between two parallel sealing members (3). The inner ring contour of the parallel sealing member (3) matches the outer contour dimension of the membrane frame (4), forming a planar limiting constraint on the membrane electrode (2). Each bipolar plate (1) has a sealing groove (5) on the outer periphery of its upper and lower surfaces, and the bottom of the sealing groove (5) is provided with the first limiting groove (6). Four gas channel unit slots (7) are opened through each of the bipolar plates (1) and the top cover (13). A rod hole (9) is opened through the bipolar plate (1) to allow the titanium alloy rod (8) to pass through. At least four titanium alloy rods (8) are provided. The upper end of the titanium alloy rod (8) is screwed with the rod nut (20). The lower end of the titanium alloy rod (8) is fixedly installed on the bottom cover (14). The lower surface of the bipolar plate (1) at the bottom of the fuel cell is provided with the positive current collector (10), which is fixedly installed on the upper surface of the bottom cover (14), with the insulating plate (12) installed between them. The upper surface of the bipolar plate (1) at the top of the fuel cell is provided with the negative current collector (11), which is fixedly connected to the lower surface of the top cover (13), with the insulating plate (12) installed between them. The bottom cover (14) is provided with an air inlet (15) and an air outlet (16) that are connected to the gas channel unit slot (7). The bottom cover (14) is provided with an encapsulation shell (17), and the top cover (18) is fixedly installed on the opening above the encapsulation shell (17). The external terminals (19) of the positive and negative electrodes are insulated and fixedly inserted into the encapsulation shell (17) and connected to the corresponding positive current collector (10) or negative current collector (11).

2. The parallel sealing and multi-stack integrated packaging structure of bipolar plates for UAV fuel cells as described in claim 1, characterized in that: Two adjacent bipolar plates (1), one membrane electrode (2) and two parallel sealing members (3) constitute a single battery cell unit. Multiple single battery cells are electrically connected in series to form a single stack module. Multiple single stack modules are connected in parallel to form a fuel cell system. The fuel cell is encapsulated inside the bottom end cover (14), the encapsulation shell (17) and the top cover (18), which together form an encapsulation and sealing structure.

3. The parallel sealing and multi-stack integrated packaging structure of bipolar plates for UAV fuel cells as described in claim 2, characterized in that: The sealing groove (5) opened on the outer periphery of the upper and lower surfaces of the bipolar plate (1) is a closed-loop rectangular groove. The bottom of the sealing groove (5) is provided with a first limiting groove (6) of the closed-loop rectangle with the same contour. The sealing groove (5) is assembled together with the corresponding electrode plate parallel sealing element (3).

4. The parallel sealing and multi-stack integrated packaging structure of bipolar plates for UAV fuel cells as described in claim 3, characterized in that: The parallel sealing component (3) of the electrode plate includes a closed-loop sealing gasket (31), a supporting sealing block (32), and a second limiting groove (33). Several supporting sealing blocks (32) are evenly embedded in the closed-loop sealing gasket (31) to form a through-type integrated structure. The end face of the supporting sealing block (32) is flush with the upper and lower surfaces of the closed-loop sealing gasket (31). The second limiting groove (33) is opened on one surface of the closed-loop sealing gasket (31). The closed-loop sealing gasket (31) is assembled in the sealing groove (5) corresponding to the bipolar plate (1).

5. The parallel sealing and multi-stack integrated packaging structure of bipolar plates for UAV fuel cells as described in claim 4, characterized in that: The closed-loop sealing gasket (31) is a rectangular sealing gasket structure. The surface of the closed-loop sealing gasket (31) with the second limiting groove (33) is assembled in the sealing groove (5). The other side surface of the closed-loop sealing gasket (31) is a plane. The plane of the closed-loop sealing gasket (31) is in contact with the surface of the membrane frame (4) of the membrane electrode (2).

6. The parallel sealing and multi-stack integrated packaging structure of bipolar plates for UAV fuel cells as described in claim 5, characterized in that: The second limiting groove (33) provided on the closed-loop sealing gasket (31) corresponds to the first limiting groove (6) provided at the bottom of the sealing groove (5). The second limiting groove (33) and the first limiting groove (6) form an adhesive limiting sealing cavity, and the colloid solidifies in the adhesive limiting sealing cavity to form an adhesive limiting body.

7. The parallel sealing and multi-stack integrated packaging structure of bipolar plates for UAV fuel cells as described in claim 1, characterized in that: The bottom cover (14), the encapsulation shell (17), and the top cover (18) are all encapsulation structures made of insulating materials. The lower opening of the encapsulation shell (17) is encapsulated by the bottom cover (14), and the upper opening is encapsulated by the rectangular top cover (18). A sealing gasket is installed between the encapsulation shell (17), the bottom cover (14), and the top cover (18). The bottom cover (14) and the top cover (18) are fixedly connected to the encapsulation shell (17) by bolts.

8. The parallel sealing and multi-stack integrated packaging structure of bipolar plates for UAV fuel cells as described in claim 1, characterized in that: Several gas channel unit slots (7) provided in the bipolar plates (1) correspond to each other and are on the same vertical line. Several gas channel unit slots (7) and airflow pipes provided in the bipolar plates (1) form two gas flow airflow channel units. The two airflow channel units are respectively connected to the air inlet (15) and air outlet (16) provided in the bottom end cover (14). The bipolar plates (1) are provided with air inlets that communicate with the gas channel unit slots (7). The gas channel unit slots (7) are connected to the airflow pipes provided in the bipolar plates (1) through the air inlets. The air inlets (15) and air outlets (16) are connected to the hydrogen inlet pipe and exhaust pipe through manifolds.

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