A gravity refueling assembly for a drone

Abstract

This invention discloses a gravity refueling assembly for unmanned aerial vehicles (UAVs), belonging to the field of UAV fuel system technology. It includes a refueling port cap, a refueling port base, a fuel funnel, a fuel baffle, and a fuel pipe. The refueling port base and the fuel funnel are respectively sealed and fixed to the inner and outer sides of the upper skin of a first fuel tank. The fuel funnel has a leakage hole on its side wall, and its lower part is a conical funnel section that is sealed and connected to the fuel pipe. The fuel baffle is a movable component with a sealing cone that matches the taper of the inner wall of the conical funnel section, and a sealing element is provided between the two. When the fuel baffle is in the sealed working position, the leakage hole is located above the sealing cone. When the refueling port cap is locked, it presses against the fuel baffle, causing the sealing element to be squeezed against the inner wall of the conical section to block the fuel passage. The end of the fuel pipe is connected to a second fuel tank via a frame connector. This invention can achieve gravity refueling and fuel transfer between two fuel tanks with a single refueling assembly, significantly saving internal space in the UAV, increasing fuel capacity and range, and featuring high reliability of the conical seal, simple structure, and low manufacturing cost.

Description

Technical Field

[0001] This invention belongs to the field of drone fuel system technology, specifically relating to a drone gravity refueling component that enables dual fuel tank refueling. Background Technology

[0002] Gravity refueling units are a crucial component of large UAV fuel systems. Installed at the highest point on top of each fuel tank, they refuel using the weight of the fuel itself. This method offers advantages such as simple refueling equipment, strong field adaptability, and low maintenance costs, making it a commonly used refueling method for small, medium, and large UAVs. In addition to refueling, gravity refueling units also seal the fuel tanks during flight, preventing rainwater, dust, salt spray, and other external impurities from entering the tanks. They also prevent fuel spillage during changes in flight attitude, ensuring the reliability of the fuel system and flight safety.

[0003] As large unmanned aerial vehicles (UAVs) develop towards longer endurance and greater range, the internal structure of the fuselage is limited by the frame and the layout of onboard equipment. Therefore, a distributed arrangement of multiple irregularly shaped fuel tanks is typically adopted to fully utilize the fragmented space within the fuselage and wings and maximize fuel capacity. In traditional designs, each independent fuel tank requires a corresponding complete gravity refueling cap assembly, and each refueling port needs to have operating space and installation interfaces reserved on the top of the tank.

[0004] This design has several shortcomings: First, due to installation location limitations, it is difficult to find suitable refueling port locations for some irregularly shaped fuel tanks, and sufficient space cannot be reserved for opening and refueling operations, which greatly restricts the layout of the fuel tanks and the overall structural design. Second, multiple refueling port assemblies increase the overall structural weight and sealing points, which not only reduces the effective fuel-carrying space but also increases the risk of fuel leakage and the workload of daily maintenance. Third, refueling operations require operation on each fuel tank individually, making the refueling process cumbersome and the work efficiency low.

[0005] While some current solutions achieve cross-tank refueling by adding an electric oil pump, this increases system complexity and failure rate due to the added power components and control circuitry, making it unsuitable for UAV platforms with high reliability and lightweight requirements. Therefore, there is an urgent need for a gravity refueling assembly that is simple in structure, requires no additional power, and can achieve controllable refueling of multiple tanks through a single refueling port, in order to solve many of the problems in existing technologies. Summary of the Invention

[0006] The purpose of this invention is to solve the problems of difficult arrangement of refueling ports for multi-tank drones, large space occupation, and high manufacturing cost in the prior art. It provides a gravity refueling component for drones, which realizes fuel filling and fuel transfer between two tanks through a single gravity refueling structure, saving internal space, improving fuel loading capacity, and ensuring sealing reliability and ease of operation.

[0007] To achieve the above objectives, the present invention provides a gravity refueling component for unmanned aerial vehicles, including a refueling port cover, a refueling port base, an oil funnel, an oil baffle plate, and an oil pipe. The filler port base and the oil funnel are respectively sealed and fixed to the outer and inner sides of the upper skin of the first oil tank, and their internal flow channels are aligned and connected. The side wall of the oil-connecting funnel is provided with at least one oil leakage hole. The lower part of the oil-connecting funnel is a conical funnel section. The lower end of the conical funnel section narrows to form an oil outlet. The oil outlet is sealed and connected to the upper end of the oil-connecting pipe. The oil baffle is a movable part that can be placed inside the oil funnel and in a sealed working position; the oil baffle has a sealing cone, the outer cone surface of which matches the taper of the inner wall of the conical funnel section, and a sealing element is provided between the sealing cone and the inner wall of the conical funnel section; When the oil baffle is in the sealing working position, the oil leakage hole is located above the sealing cone. The filler cap and the filler base are detachably locked together. When the filler cap and the filler base are locked together, the inner side of the filler cap presses against the upper part of the oil baffle, causing the sealing cone to press down, so that the sealing element is squeezed and adhered to the inner wall of the conical funnel section, blocking the oil passage between the oil outlet and the upper chamber of the oil funnel. The lower end of the oil pipe is provided with a frame-connected joint, which is used to seal the oil tank frame and connect to the inside of the second oil tank.

[0008] Furthermore, the lower end of the filler port base is provided with a first flange face, and the upper end of the oil funnel is provided with a second flange face; the first flange face is attached to the outer surface of the upper skin of the first oil tank, and the second flange face is attached to the inner surface of the upper skin of the first oil tank, and the first flange face and the second flange face are clamped and fixed by fasteners.

[0009] Furthermore, sealing gaskets are provided between the first flange face and the upper skin of the first oil tank, and between the second flange face and the upper skin of the first oil tank, to achieve static sealing of the flange mounting surfaces.

[0010] Furthermore, the oil funnel comprises, from top to bottom, a straight cylindrical section and a conical funnel section, with the oil leakage hole located on the side wall of the straight cylindrical section.

[0011] Furthermore, the sidewall of the straight section is uniformly provided with a plurality of oil leakage holes; the oil leakage holes are used on the one hand to guide the fuel to the first fuel tank where the fuel funnel is located, and on the other hand to allow excess fuel to overflow into the first fuel tank when the second fuel tank at the far end is filled to overflow, so as to prevent fuel from overflowing from the filler port.

[0012] Furthermore, the oil baffle has an inverted T-shaped cross-section, with a column section at the top and a sealing cone section at the bottom. The column section is vertically positioned at the center of the top surface of the sealing cone section, and the top of the column section is directly opposite the center of the inner side of the filler cap, which is used to uniformly transmit the downward pressure of the filler cap and ensure that the circumferential clamping force of the seal is consistent.

[0013] Furthermore, the sealing element is a sealing ring, and an annular groove is provided on the outer edge of the sealing cone, and the sealing ring is embedded in the annular groove.

[0014] Furthermore, the filler cap and the filler base are fitted with a rotary locking mechanism.

[0015] Furthermore, both the oil funnel and the oil baffle are integral machined metal parts with high machining precision, good structural strength, and are suitable for aviation use environments.

[0016] Furthermore, the through-frame joint is sealed and fixed on the partition frame of two adjacent oil tanks, and the oil pipe passes through the partition frame and achieves through-wall sealing through the through-frame joint, ensuring the sealing performance of the partition frame of the two oil tanks.

[0017] Compared with the prior art, the present invention has the following beneficial effects: It saves internal space and increases fuel loading capacity. Only one gravity refueling assembly is needed for installation and operation to refuel both fuel tanks. There is no need to set up a separate refueling port for the second fuel tank at the far end. This reduces the internal space requirements for fuel tank layout, can increase fuel tank volume, and improve the range and flight time of the UAV. It is especially suitable for large UAVs with compact internal space and many irregularly shaped fuel tanks.

[0018] The refueling mode is flexible and easy to operate. The target fuel tank can be switched by removing or removing the baffle plate: when the baffle plate is in place, fuel is added to the first fuel tank through the drain hole; when the baffle plate is removed, fuel is added to the second fuel tank through the fuel line. The operation logic is simple and convenient for on-site use.

[0019] The conical sealing structure is reliable and has a good self-centering effect. The oil baffle adopts a sealing form in which the sealing cone part and the conical funnel section cooperate, which has an automatic centering effect. The greater the locking force of the oil filler cap, the more sufficient the sealing element is pressed against the cone wall. It can still maintain stable sealing performance under the vibration environment of UAV flight and prevent accidental oil leakage between the two oil tanks.

[0020] It features overflow protection. The oil drain hole on the side wall of the oil funnel can also serve as an overflow channel. When the second oil tank is overfilled, the excess fuel can flow back to the first oil tank through the drain hole, preventing fuel from overflowing from the filler neck and improving filling safety.

[0021] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0022] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.

[0023] Figure 1 This is a schematic diagram of the overall three-dimensional structure of the UAV gravity refueling component described in an embodiment of the present invention; Figure 2 This is a cross-sectional view of the gravity refueling assembly for unmanned aerial vehicles (UAVs) according to an embodiment of the present invention. Figure 3 This is a cross-sectional view of the oil baffle plate according to an embodiment of the present invention; Figure 4 This is a top view of the oil funnel described in an embodiment of the present invention; Figure 5 This is a cross-sectional view (AA) of the oil funnel described in an embodiment of the present invention; Figure 6 This is a schematic diagram showing the layout of the UAV gravity refueling component installed in a dual fuel tank according to an embodiment of the present invention.

[0024] Explanation of markings in the diagram: 1. Filler cap; 2. Filler base; 21. First flange face; 3. Oil funnel; 31. Second flange face; 32. Straight section; 33. Conical funnel section; 34. Oil drain hole; 35. Oil outlet; 4. Oil baffle; 41. Column section; 42. Sealing cone; 5. Oil pipe; 6. Frame connector; 7. Sealing ring; 100. First oil tank; 200. Second oil tank. Detailed Implementation

[0025] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0026] like Figure 1 , Figure 2 As shown, the gravity refueling assembly for unmanned aerial vehicles disclosed in this invention mainly consists of a refueling port cover 1, a refueling port base 2, an oil funnel 3, an oil baffle 4, an oil pipe 5, a frame connector 6, and a sealing component. The entire assembly is installed on the top skin of the first fuel tank and is connected to the second fuel tank through the oil pipe 5 and the frame connector 6, thereby realizing gravity refueling of the two fuel tanks from a single refueling port.

[0027] The lower end of the filler cap base 2 is integrally provided with a first flange face 21, on which multiple mounting through holes are evenly opened. The filler cap 1 and the filler cap base 2 are a rotary locking fit structure commonly used in the aviation field. After rotating to the correct position, it can lock and seal. Reverse rotation can unlock and remove the filler cap 1, thus opening the filler cap. During installation, the filler cap base 2 is placed on the upper surface of the upper skin of the first fuel tank, with the first flange face 21 fitting against the outer surface of the skin. The upper end of the fuel funnel 3 is integrally provided with a second flange face 31, which fits against the lower surface of the upper skin of the fuel tank. Bolts pass through the first flange face 21, the upper skin of the fuel tank, and the second flange face 31 from top to bottom and are then locked to clamp and fix the three together. Sealing gaskets are placed between the first flange face 21 and the upper skin of the fuel tank, and between the second flange face 31 and the skin, to achieve static sealing of the mounting surfaces and prevent fuel leakage from the mounting gaps.

[0028] like Figure 4 , Figure 5 As shown, the oil funnel 3 is a one-piece machined metal part, shaped like a funnel, and divided into three parts from top to bottom: a second flange face 31, a straight section 32, and a conical funnel section 33. The straight section 32 is a cylindrical structure with a uniform inner diameter, and multiple oil leakage holes 34 are evenly distributed around its side wall. The oil leakage holes 34 penetrate the wall of the straight section 32 and serve as the channel for fuel to enter the first fuel tank. At the same time, the oil leakage holes 34 can also serve as overflow holes. When the second fuel tank at the far end is full, the excess fuel can flow back along the oil connecting pipe 5 and into the first fuel tank through the oil leakage holes 34, preventing fuel from overflowing from the top filling port. The conical funnel section 33 is connected to the lower end of the straight section 32, and its inner diameter gradually narrows from top to bottom, narrowing to a circular oil outlet 35 at the end. The oil outlet 35 is sealed and fixedly connected to the upper end of the oil connecting pipe 5, allowing fuel to flow into the oil connecting pipe 5 through the oil outlet 35.

[0029] like Figure 3 As shown, the oil baffle 4 is a one-piece machined metal part with an inverted T-shaped cross-section, including an upper column section 41 and a lower sealing cone section 42. The column section 41 is vertically positioned at the center of the top surface of the sealing cone section 42, with its top end facing the inner bottom surface of the filler cap 1. It is used to transmit the downward pressure when the filler cap 1 is locked, ensuring that the sealing cone section 42 is subjected to uniform force in the circumference. The outer conical surface of the sealing cone section 42 is perfectly matched with the inner wall taper of the conical funnel section 33 of the oil funnel 3. An annular groove is formed on the outer edge of the sealing cone section 42, and the sealing ring 7, which serves as a sealing element, is embedded in the annular groove. The natural outer diameter of the sealing ring 7 is larger than the maximum outer diameter of the sealing cone section 42.

[0030] The baffle plate 4 is a movable part, which can be inserted or removed from the upper opening of the oil funnel 3. Under normal conditions, the baffle plate 4 is placed inside the oil funnel 3. When the filler cap 1 is locked, the inner side of the filler cap 1 presses down on the top of the column section 41, pushing the entire baffle plate 4 downward. The sealing ring 7 on the outer edge of the sealing cone 42 is then pressed against the inner wall of the conical funnel section 33. The wedge-shaped clamping force of the cone surface causes the sealing ring 7 to undergo elastic deformation, forming a circumferential seal, completely blocking the oil passage between the straight section 32 and the lower oil outlet 35, preventing fuel from flowing into the oil pipe 5. At this time, the oil leakage hole 34 on the straight section 32 is located above the sealing cone 42, ensuring that fuel can flow normally into the fuel tank through the oil leakage hole 34.

[0031] The fuel line 5 is a rigid fuel line. Its upper end is sealed to the outlet 35 of the fuel funnel 3. The line extends downwards along the inside of the first fuel tank and then bends horizontally, passing through the partition between the two fuel tanks and extending into the second fuel tank. The partition joint 6 is sealed and fixed to the partition between the two fuel tanks. When the fuel line 5 passes through the partition, the partition joint 6 achieves sealing and fixation at the wall penetration point, ensuring the airtightness of the fuel tank partition and preventing fuel leakage from the wall penetration point.

[0032] like Figure 6 As shown, the entire drone gravity refueling assembly is installed on top of the first fuel tank. The fuel line 5 is connected to the second fuel tank through the frame connector 6. The two refueling modes can be switched by removing and placing the fuel baffle 4.

[0033] When refueling the first fuel tank, simply rotate and remove the fuel filler cap 1, leaving the baffle plate 4 inside the fuel funnel 3. As fuel is poured into the filler, it falls into the straight section 32 of the fuel funnel 3. Because the lower conical funnel section 33 is blocked by the baffle plate 4 and the seal, the fuel cannot flow downwards into the fuel pipe 5. Instead, it flows out through the leakage hole 34 on the side wall of the straight section 32 and directly into the first fuel tank, completing the refueling of this tank. After refueling, reinstall the fuel filler cap 1 back onto the fuel filler base 2 and lock it in place. The inside of the fuel filler cap 1 presses against the column section 41 of the baffle plate 4, further pressing the seal against the inner wall of the conical funnel section 33. This ensures a reliable seal during flight, preventing accidental fuel leakage between the two fuel tanks and preventing fuel overflow from the filler cap.

[0034] When refueling the second fuel tank, first remove the filler cap 1, then remove the baffle plate 4 from the fuel funnel 3 upwards. As fuel is injected into the filler cap, it passes sequentially through the straight section 32 and the conical funnel section 33, flowing directly from the lower outlet 35 into the fuel pipe 5. It then flows along the fuel pipe 5 through the frame connector 6 and finally into the second fuel tank, completing the cross-tank refueling. If the second fuel tank reaches full capacity during refueling, excess fuel will flow back along the fuel pipe 5 into the fuel funnel 3, and then overflow into the first fuel tank through the drain hole 34 on the side wall of the straight section 32, preventing overflow from the top filler cap and improving the safety of the refueling operation. After refueling, place the baffle plate 4 back into the fuel funnel 3, then reinstall and lock the filler cap 1 to restore the flight seal.

[0035] This invention achieves independent refueling of dual fuel tanks using a single gravity refueling assembly through the combination of a fuel funnel, a movable fuel baffle, and a fuel pipe. This eliminates the need for refueling ports and operating space in each tank, significantly reducing the fuel system's footprint on the UAV's internal space. This facilitates increased fuel tank capacity and improves the UAV's range and flight time. Simultaneously, the conical sealing structure provides a self-centering effect, with sealing reliability increasing with tightening force, adapting to the vibration environment during UAV flight. The overall structure primarily consists of simple machined parts, resulting in low manufacturing costs, convenient maintenance, and significant engineering application value.

[0036] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A gravity refueling component for unmanned aerial vehicles (UAVs), characterized in that, It includes a filler cap (1), a filler base (2), an oil funnel (3), an oil baffle (4), and an oil pipe (5); The oil filler base (2) and the oil funnel (3) are respectively sealed and fixed to the outer and inner sides of the upper skin of the first oil tank, and their internal flow channels are aligned and connected. The side wall of the oil funnel (3) is provided with at least one oil leakage hole (34). The lower part of the oil funnel (3) is a conical funnel section (33). The lower end of the conical funnel section (33) shrinks to form an oil outlet (35). The oil outlet (35) is sealed and connected to the upper end of the oil pipe (5). The oil baffle (4) is a movable part that can be placed inside the oil funnel (3) and in a sealed working position; the oil baffle (4) has a sealing cone (42), the outer cone surface of the sealing cone (42) matches the taper of the inner wall of the conical funnel section (33), and a sealing element is provided between the sealing cone (42) and the inner wall of the conical funnel section (33); When the oil baffle (4) is in the sealing working position, the oil leakage hole (34) is located above the sealing cone (42); The filler cap (1) and the filler base (2) are detachably locked together. When the filler cap (1) and the filler base (2) are locked together, the inner side of the filler cap (1) presses against the upper part of the oil baffle (4), causing the sealing cone (42) to press down, so that the sealing element is squeezed and adhered to the inner wall of the conical funnel section (33), blocking the oil passage between the oil outlet (35) and the upper chamber of the oil funnel (3). The lower end of the oil pipe (5) is provided with a frame connector (6), which is used to seal the oil tank frame and connect to the inside of the second oil tank.

2. The UAV gravity refueling component according to claim 1, characterized in that, The lower end of the oil filling port base (2) is provided with a first flange face (21), and the upper end of the oil funnel (3) is provided with a second flange face (31); the first flange face (21) is attached to the outer surface of the upper skin of the first oil tank, and the second flange face (31) is attached to the inner surface of the upper skin of the first oil tank. The first flange face (21) and the second flange face (31) are clamped and fixed by fasteners.

3. The UAV gravity refueling component according to claim 2, characterized in that, A sealing gasket is provided between the first flange face (21) and the upper skin of the first oil tank, and between the second flange face (31) and the upper skin of the first oil tank, to achieve static sealing of the flange mounting surface.

4. The UAV gravity refueling assembly according to claim 1, characterized in that, The oil funnel (3) includes a straight section (32) and a conical funnel section (33) from top to bottom, and the oil leakage hole (34) is opened on the side wall of the straight section (32).

5. The UAV gravity refueling assembly according to claim 4, characterized in that, The straight section (32) has a plurality of oil leakage holes (34) evenly distributed around its sidewall.

6. The UAV gravity refueling assembly according to claim 1, characterized in that, The cross-section of the oil baffle (4) is inverted T-shaped, with the upper part being a column section (41) and the lower part being the sealing cone (42). The column section (41) is vertically arranged at the center of the top surface of the sealing cone (42), and the top of the column section (41) is directly opposite the inner center of the filler cap (1) to transmit the downward pressure of the filler cap (1).

7. The UAV gravity refueling assembly according to claim 1, characterized in that, The sealing element is a sealing ring (7), and the outer edge of the sealing cone (42) is provided with an annular groove, and the sealing ring (7) is embedded in the annular groove.

8. The UAV gravity refueling assembly according to claim 1, characterized in that, The filler cap (1) and the filler base (2) are rotated and locked together.

9. The UAV gravity refueling assembly according to claim 1, characterized in that, The oil funnel (3) and the oil baffle (4) are both integral metal machined parts.

10. The UAV gravity refueling assembly according to claim 1, characterized in that, The through-frame connector (6) is sealed and fixed on the partition frame of two adjacent oil tanks. The oil pipe (5) passes through the partition frame and achieves through-wall sealing through the through-frame connector (6).

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