Unmanned Aerial Vehicle (UAV) Fueling Systems and Fixed-Wing UAVs

Abstract

This invention relates to a fuel system for a fixed-wing UAV, comprising: a main fuel tank disposed in the wing of the UAV; and an auxiliary fuel tank disposed in the fuselage of the UAV and positioned spaced apart from the main fuel tank in the yaw direction, the auxiliary fuel tank being fluidly connected to the main fuel tank and supplying fuel to the engine of the fixed-wing UAV via the main fuel tank; wherein the main fuel tank is located at 0% to 25% of the wing span, while the auxiliary fuel tank is located at 40% to 70% of the fuselage length from the nose. This arrangement of the UAV fuel system allows the center of gravity of the fixed-wing UAV to vary between 23% and 31% of its MAC (Macro-Maneuvering Capacity). By designing the fuel tank shape and arranging its position according to the above constraints, the fuel consumption center of gravity curve is controlled, thereby meeting the center of gravity requirements for scaled-down flight maneuvers. Furthermore, this invention also relates to a fixed-wing UAV.

Description

Technical Field

[0001] This invention belongs to the field of unmanned aerial vehicle (UAV) fuel system technology, and relates to a UAV fuel system that realizes refueling / discharging / supplying, weight and center of gravity control, and real-time measurement functions. Additionally, this invention also relates to a fixed-wing UAV. Background Technology

[0002] With the rapid rise of the drone industry, different types of drone products have emerged, including rotary-wing drones, fixed-wing drones, and compound-wing drones, each with different fuel systems.

[0003] For example, the following patents all mention a fuel system and control method specific to a certain type of UAV:

[0004] (1) A utility model patent entitled “A fuel system for unmanned aerial vehicles”, filed by Shenyang Xuanfei Aviation Technology Co., Ltd. and published on August 16, 2019;

[0005] (2) A utility model patent entitled "A Drone Fuel System" filed by Wofei Changkong Technology (Chengdu) Co., Ltd. and published on September 6, 2022, with application number 202220842315.0.

[0006] (3) The invention patent filed by Rainbow Unmanned Aerial Vehicle Technology Co., Ltd. and published on April 18, 2023, with application number 202211730480.8, entitled "An active control fuel center of gravity oil transfer system and method, and an unmanned aerial vehicle"; and

[0007] (4) The invention patent with application number 201911400455.1, entitled "A Fuel System and Control Method for a Large Cargo Unmanned Aerial Vehicle," filed by Aerospace Era Feihong Technology Co., Ltd. and published on May 12, 2020. However, the fuel systems disclosed in these patents do not exhibit the characteristics of scaled-down verification. In particular:

[0008] 1) The reasonable control of the fuel consumption center of gravity curve was not considered;

[0009] 2) It does not have the function of real-time weight and center of gravity calculation;

[0010] 3) The fuel tank does not have a wave deflector design;

[0011] 4) The fuel tank lacks a three-dimensional design;

[0012] Therefore, there is still a need for an improved drone fuel system that can overcome one or more of the shortcomings of the existing technology. Summary of the Invention

[0013] The purpose of this invention is to provide a fuel system for unmanned aerial vehicles (UAVs) that meets the center of gravity requirements for scaled-down flight maneuvers of fixed-wing UAVs.

[0014] According to one aspect of the present invention, a fuel system for an unmanned aerial vehicle (UAV) is provided, comprising: a main fuel tank disposed in the wing of the fixed-wing UAV; and an auxiliary fuel tank disposed in the fuselage of the fixed-wing UAV and positioned spaced apart from the main fuel tank in the heading direction, wherein the auxiliary fuel tank is fluidly connected to the main fuel tank and supplies fuel to the engine of the fixed-wing UAV via the main fuel tank; wherein the main fuel tank is located at 0% to 25% of the wing span, while the auxiliary fuel tank is located at 40% to 70% of the fuselage length starting from the nose.

[0015] This UAV fuel system arrangement allows the center of gravity (CW) of the fixed-wing UAV to vary between 23% and 31% of its mean chord (MAC) during fuel consumption. The CW refers to the point where the UAV's gravity acts, typically expressed as a percentage of the mean aerodynamic chord (MAC). By designing the fuel tank shape and arranging its position according to these constraints, the fuel consumption CW curve can be controlled, thus meeting the CW requirements for scaled-down flight maneuvers.

[0016] According to the above aspects of the present invention, preferably, the main fuel tank can be positioned between the front spar and the rear spar of the wing, and includes an inner section close to the fuselage and an outer section away from the fuselage, wherein the inner section is located at 25% to 50% of the wing chord and the outer section is located at 15% to 40% of the wing chord.

[0017] This fuel tank arrangement allows for control of the center of gravity as fuel is consumed. For example, as fuel is consumed, the center of gravity of a fixed-wing UAV can shift from approximately 24% MAC to approximately 31% MAC, and then back to approximately 23% MAC.

[0018] According to the above aspects of the present invention, in order to better control the fuel consumption center of gravity curve, preferably, the main fuel tank may include a first main fuel tank and a second main fuel tank arranged symmetrically about the fuselage, and in the inner section, the first main fuel tank is arranged against the second main fuel tank.

[0019] According to the above aspects of the present invention, preferably, the external shape of the main fuel tank can conform to the internal space of the wing, and / or the external shape of the auxiliary fuel tank can conform to the internal space of the fuselage.

[0020] The fixed-wing UAV is scaled down from the prototype, so the main fuel tank retains the airfoil characteristics and the auxiliary fuel tank retains the multi-segment arc characteristics, thereby meeting the spatial constraints of the wing and fuselage structural design and better simulating the outline of the prototype.

[0021] According to the above aspects of the present invention, preferably, the UAV fuel system may further include an anti-bubble fuel tank fluidly connected to the main fuel tank, wherein fuel is added to the main fuel tank via the anti-bubble fuel tank, and fuel is supplied from the main fuel tank to the engine of the fixed-wing UAV via the anti-bubble fuel tank.

[0022] This type of anti-bubble fuel tank can minimize the formation of air bubbles in the fuel, especially during refueling or fuel supply.

[0023] According to the above aspects of the present invention, preferably, the UAV fuel system may further include a flow meter fluidly connected between the anti-bubble fuel tank and the engine of the fixed-wing UAV.

[0024] In this way, the fuel will flow through the flow meter, and the weight of the fuel consumed can be measured. Based on ground calibration tests, the weight and center of gravity of the aircraft can be calculated in real time.

[0025] According to the above aspects of the present invention, preferably, wave deflectors can be respectively provided in the main fuel tank and the auxiliary fuel tank, the wave deflectors being arranged along the heading direction and located at 40% to 50% of the span of the corresponding main fuel tank and auxiliary fuel tank. This arrangement of wave deflectors effectively prevents the adverse effects of fuel sloshing on the center of gravity during aircraft maneuvers.

[0026] According to the above aspects of the present invention, in order to further reduce the adverse effects of fuel sloshing on the center of gravity, preferably, an oil passage hole is provided on the circumferential edge of the baffle, the diameter of which is 4% to 8% of the long side length of the baffle.

[0027] According to the above aspects of the present invention, preferably, the main oil tank and the auxiliary oil tank are respectively provided with a low-level opening and a high-level opening, wherein the low-level opening is respectively (or each) in fluid communication with the counterweight inside the main oil tank and the auxiliary oil tank, and the high-level opening is respectively located at the local highest point of the main oil tank and the auxiliary oil tank.

[0028] By closing and opening these openings, the fuel tank's refueling, emptying, and supply operations can be controlled as needed.

[0029] According to another aspect of the invention, a fixed-wing unmanned aerial vehicle (UAV) is provided, which may include an UAV fuel system according to the above aspects.

[0030] In particular, the beneficial technical effects of the UAV fuel system according to the present invention may include, but are not limited to:

[0031] 1) This invention achieves control of the fuel consumption center of gravity curve by rationally designing the shape and arranging the position of the fuel tank, thereby meeting the center of gravity requirements of scaled-down flight subjects.

[0032] 2) This invention calibrates the fuel flow meter and measures the fuel consumption curve through ground fuel consumption tests, thereby enabling real-time calculation of the aircraft's weight and center of gravity.

[0033] 3) Each fuel tank in this invention is designed with a wave deflector, which can effectively prevent the adverse effects of fuel sloshing on the center of gravity during aircraft maneuvers.

[0034] 4) The UAV involved in this invention is a scaled-down version of the prototype, and therefore differs from conventional rotary-wing UAVs, fixed-wing UAVs and hybrid-wing UAVs. The design of the main fuel tank and auxiliary fuel tank must be fully considered.

[0035] Therefore, the drone fuel system of the present invention can meet the usage requirements, overcome the shortcomings of the prior art, and achieve the intended purpose. Attached Figure Description

[0036] To further describe the UAV fueling system according to the present invention clearly, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments, in which:

[0037] Figure 1 A schematic diagram of a fixed-wing unmanned aerial vehicle (UAV) including an unmanned aerial vehicle (UAV) fuel system according to a non-limiting embodiment of the present invention is shown.

[0038] Figure 2 A fuel consumption center of gravity curve of a fixed-wing UAV including an UAV fuel system according to a non-limiting embodiment of the present invention is shown;

[0039] Figure 3 A schematic diagram of the fuel circuit of a drone fuel system according to a non-limiting embodiment of the present invention is shown;

[0040] Figure 4 A schematic diagram showing the mounting position of an unmanned aerial vehicle (UAV) fuel system on a fixed-wing UAV according to a non-limiting embodiment of the present invention is illustrated.

[0041] Figure 5 A schematic diagram of a drone fuel system according to a non-limiting embodiment of the present invention is shown;

[0042] Figure 6 A schematic perspective view of the main fuel tank according to a non-limiting embodiment of the present invention is shown;

[0043] Figure 7 Shown in different views Figure 6 The main fuel tank shown;

[0044] Figure 8 It shows Figure 6 A top view of the main fuel tank shown;

[0045] Figure 9 It shows crossing Figure 8 The sectional view taken by section line AA in the diagram;

[0046] Figure 10 A schematic diagram of a wave-damping plate according to a non-limiting embodiment of the present invention is shown;

[0047] Figure 11-14 It shows crossing Figure 8 Cross-sectional views taken from different section lines in the image;

[0048] Figure 15 It shows Figure 6 Another top view of the main fuel tank shown;

[0049] Figure 16 It shows crossing Figure 15 A sectional view taken by the section lines in the diagram;

[0050] Figure 17 A schematic perspective view of an auxiliary fuel tank according to a non-limiting embodiment of the present invention is shown;

[0051] Figure 18 Shown in different views Figure 17 The auxiliary fuel tank shown;

[0052] Figure 19 Another schematic perspective view of an auxiliary fuel tank according to a non-limiting embodiment of the present invention is shown;

[0053] Figure 20 It shows Figure 19 A top view of the auxiliary fuel tank shown;

[0054] Figure 21 It shows crossing Figure 20 A sectional view taken by the section lines in the diagram;

[0055] Figure 22 A schematic diagram of another wave deflector according to a non-limiting embodiment of the present invention is shown;

[0056] Figure 23-24 It shows crossing Figure 20 Cross-sectional views taken from different section lines in the image;

[0057] Figure 25 A schematic diagram of a drone fuel system according to a non-limiting embodiment of the present invention is shown;

[0058] Figure 26 Another example of a fixed-wing UAV that can be equipped with a UAV fuel system according to a non-limiting embodiment of the present invention is shown; and

[0059] Figure 27Another example of a fixed-wing drone that can be equipped with a drone fuel system according to a non-limiting embodiment of the present invention is shown.

[0060] The above figures are for illustrative purposes only and are not drawn to scale.

[0061] The reference numerals in the figures are listed in the figures and embodiments:

[0062] 200 fixed-wing unmanned aerial vehicles, including:

[0063] 100-Unmanned Aerial Vehicle (UAV) fuel system, including:

[0064] 10-Main fuel tank, including:

[0065] 101-Inner Section;

[0066] 102-Outer segment;

[0067] 10A - First main fuel tank;

[0068] 10B - Second main fuel tank;

[0069] 11-First opening;

[0070] 11A - First internal pipeline;

[0071] 11B - First Hammer;

[0072] 12-Second opening;

[0073] 13 - Third opening; 20 - Auxiliary fuel tank, including:

[0074] 21-Fourth opening;

[0075] 21A - Second internal pipeline;

[0076] 21B - Second Hammer;

[0077] 22-The fifth opening;

[0078] 22A - Third internal pipeline;

[0079] 22B - Third Hammer;

[0080] 23 - The sixth opening;

[0081] 24-Platform Department;

[0082] 24A - Protrusion; 30 - Anti-bubble oil tank, including:

[0083] 30A - First Anti-bubble Oil Tank;

[0084] 30B - Second anti-bubble oil tank;

[0085] 31 - The first bite;

[0086] 32 - Second bite;

[0087] 33 - Third port; 40 - Flow meter, including:

[0088] 40A - First Flow Meter;

[0089] 40B - Second flow meter; 50 - Wave shield, including:

[0090] 50A - Oil passage hole;

[0091] 51-First wave deflector;

[0092] 52 - Second wave deflector;

[0093] 60 - Engine oil pump, including:

[0094] 60A - First engine oil pump;

[0095] 60B - Second engine oil pump;

[0096] 70 - Piping accessories, including:

[0097] 71 - Gas filler cap;

[0098] 72 - Switch valve;

[0099] 80 oil filter, including:

[0100] 80A - First oil filter;

[0101] 80B - Second oil filter;

[0102] 200A One-head unit;

[0103] 201-wing, including:

[0104] 201A - First Wing

[0105] 201B - Second Wing

[0106] 202 - Fuselage;

[0107] 203 - Engine, including:

[0108] 203A - First Engine;

[0109] 203B - Second Engine;

[0110] F - Heading direction. Detailed Implementation

[0111] It should be understood that, unless explicitly stated otherwise, the invention may employ various alternative orientations and sequences of steps. It should also be understood that the specific apparatus shown in the drawings and described in the specification are merely exemplary embodiments of the inventive concept disclosed and defined herein. Therefore, unless expressly stated otherwise, the specific orientations, directions, or other physical features involved in the various disclosed embodiments should not be considered limiting.

[0112] Figure 1 A schematic diagram of a fixed-wing unmanned aerial vehicle (UAV) 200 including an UAV fuel system 100 according to a non-limiting embodiment of the present invention is shown.

[0113] As shown in the figure and as a non-limiting example, the fixed-wing UAV 200 may include a wing 201, a fuselage 202, an engine 203, and a UAV fuel system 100. The UAV fuel system 100 may be disposed on the wing 201 and the fuselage 202 for supplying fuel to the engine 203.

[0114] The fixed-wing UAV 200 according to the present invention can be a scaled-down model of various military or civilian aircraft, that is, designed to scale according to the dimensions of these aircraft, for applications such as high angle-of-attack stall, spin characteristics, and turn stall, to promote technological innovation, shorten development cycles, and reduce test flight costs. During these tests, the aircraft's center of gravity needs to be controlled within a predetermined range based on fuel consumption, thereby meeting the center of gravity requirements for scaled-down flight maneuvers.

[0115] like Figure 1 As shown, the UAV fuel system 100 may mainly include a main fuel tank 10 and an auxiliary fuel tank 20.

[0116] The main fuel tank 10 is disposed within the wing 201 of the fixed-wing UAV 200, such that the external shape of the main fuel tank 10 conforms to the internal space of the wing 201, i.e., the main fuel tank 10 maintains airfoil characteristics. For example, the main fuel tank 10 may be positioned between the front and rear spars of the wing 201, and includes an inner section 101 near the fuselage 202 and an outer section 102 away from the fuselage 202. In this example, the main fuel tank 10 may be a wing fuel tank.

[0117] As an example, the inner section 101 is located at 25% to 50% of the chord of the wing 201, while the outer section 102 is located at 15% to 40% of the chord of the wing 201. Alternatively, preferably, the main fuel tank 10 can be located at 0% to 25% of the span of the wing 201, i.e., close to the centerline of the fuselage 202.

[0118] exist Figure 1In the example shown, the main fuel tank 10 may include a first main fuel tank 10A located in a first wing 201A on the left side of the fuselage 202 and a second main fuel tank 10B located in a second wing 201B on the right side of the fuselage 202. Therefore, the first main fuel tank 10A may also be referred to as the left main fuel tank, and the second main fuel tank 10B may also be referred to as the right main fuel tank. The first main fuel tank 10A and the second main fuel tank 10B may be arranged symmetrically about the centerline of the fuselage 202 and may abut against each other at the inner section 101.

[0119] The auxiliary fuel tank 20 can be housed within the fuselage 202 of the fixed-wing UAV 200. Furthermore, the external shape of the auxiliary fuel tank 20 conforms to the internal space of the fuselage 202. In this example, the auxiliary fuel tank 20 can be a fuselage fuel tank.

[0120] The terms "main fuel tank" and "auxiliary fuel tank" used in this document are for ease of description and distinction and are not intended to impose any specific limitations. For example, a fuel tank that is directly fluidly connected to the engine and supplies fuel to the engine can be defined as the "main fuel tank."

[0121] The fixed-wing UAV 200 involved in this invention is a scaled-down prototype, and therefore differs from conventional rotary-wing UAVs, fixed-wing UAVs, and hybrid-wing UAVs, requiring careful consideration of the design of the main fuel tank and auxiliary fuel tank. Therefore, as described above, both the main fuel tank 10 and the auxiliary fuel tank 20 conform to the corresponding internal space of the fixed-wing UAV 200.

[0122] exist Figure 1 In the example shown, the auxiliary fuel tank 20 can be positioned spaced apart from the main fuel tank 10 in the heading direction F. Figure 1 In this example, the auxiliary fuel tank 20 can be positioned behind the main fuel tank 10, and the auxiliary fuel tank 20 is fluidly connected to the main fuel tank 10. Additionally, as described below, in Figure 26 and 27 In the example, the auxiliary fuel tank 20 may alternatively be positioned in front of the main fuel tank 10.

[0123] The location of the auxiliary fuel tank 20 plays a crucial role in controlling the center of gravity and requires comprehensive consideration of factors such as the total fuel volume, the proportion of fuel in the auxiliary fuel tank 20, and the overall weight of the aircraft. As shown in the figure, according to the present invention, the auxiliary fuel tank 20 is located at 40% to 70% of the length of the fuselage 202, starting from the nose 202A.

[0124] This invention achieves control of the fuel consumption center of gravity curve by rationally designing the shape and arranging the position of the fuel tank, thereby meeting the center of gravity requirements of scaled-down flight subjects.

[0125] The design of the UAV fuel system 100 of the present invention first needs to meet the flight time requirements of the verification platform, and secondly, it needs to meet the spatial constraints of the wing and fuselage structure design. Then, it needs to rationally design the fuel loading capacity of the main fuel tank and the fuel loading capacity of the auxiliary fuel tank. By rationally arranging the positions of the main fuel tank and the auxiliary fuel tank, the weight and center of gravity can be controlled as fuel is consumed.

[0126] The above-mentioned arrangement and positioning of the main fuel tank 10 and the auxiliary fuel tank 20 is beneficial. As the fixed-wing UAV 200 goes from a fully fueled state to a state where the fuel is completely consumed, the center of gravity position X of the fixed-wing UAV 200 can change between 23% MAC and 31% MAC. This range of change in the center of gravity position can meet the center of gravity requirements of the subjects of scaled-down flight.

[0127] The position of the center of gravity X can be calculated using the following equation: X = m0*X0 + m1*X1 + m2*X2 / (m0 + m1 + m2), where,

[0128] m0: The total weight of the fixed-wing UAV 200 excluding fuel;

[0129] X0: The center of gravity of the fixed-wing UAV 200 excluding fuel;

[0130] m1: Fuel load weight of main fuel tank 10;

[0131] X1: The center of gravity of the fuel in the main fuel tank 10;

[0132] m2: Fuel load weight of auxiliary fuel tank 20;

[0133] X2: The center of gravity of the fuel in the auxiliary fuel tank 20.

[0134] In addition, the positions of the main oil tank 10 and the auxiliary oil tank 20 are also constrained by the rotational inertia of the three axes of the entire machine.

[0135] Figure 2 The fuel consumption center of gravity curve of a fixed-wing unmanned aerial vehicle 200 including an unmanned aerial vehicle fuel system 100 according to a non-limiting embodiment of the present invention is shown.

[0136] Figure 2 The horizontal axis in the graph represents the centroid position (MAC), while Figure 2 The vertical axis represents the total weight of the drone's fuel system 100.

[0137] As is known in the art, the center of gravity of an aircraft is the point of application of the aircraft's gravity, usually expressed as a percentage of the mean aerodynamic chord (MAC). Therefore, the position of the aircraft's center of gravity is relative to the mean aerodynamic chord. The position of the center of gravity relative to the mean aerodynamic chord % = (length of the center of gravity projection from the leading edge of the mean aerodynamic chord / mean aerodynamic chord length) × 100%. Generally speaking, the center of gravity of 0% MAC (LEMAC) is located at the leading edge of the MAC, while the center of gravity of 100% MAC (TEMAC) will be located at the trailing edge of the MAC.

[0138] from Figure 2 As can be seen, with the consumption of fuel, the total weight of the fixed-wing UAV 200 gradually decreases from approximately 200 kg to approximately 120 kg, while the center of gravity position correspondingly changes from approximately 24% MAC to approximately 31% MAC, and then back to approximately 23% MAC. In other words, the center of gravity position can shift from a position closer to the rear of the aircraft to a position closer to the front, and then back to a position closer to the rear again. This is because the engine 203 will first consume fuel from the auxiliary fuel tank 20, and then consume fuel from the main fuel tank 10.

[0139] When conducting subject verification, the center of gravity of the subject's location waypoint can be designed by adding weights on the ground and planning the flight path.

[0140] Figure 3 A schematic diagram of the fuel circuit of an unmanned aerial vehicle (UAV) fuel system 100 according to a non-limiting embodiment of the present invention is shown; Figure 4 A schematic diagram showing the mounting position of a drone fuel system 100 on a fixed-wing drone 200 according to a non-limiting embodiment of the present invention is illustrated; while Figure 5 A schematic diagram of a drone fuel system 100 according to a non-limiting embodiment of the present invention is shown.

[0141] As shown in the figure, the UAV fuel system 100 may also include an anti-bubble fuel tank 30. The anti-bubble fuel tank 30 may be fluidly connected to the main fuel tank 10. Fuel can be added to the main fuel tank 10 via the anti-bubble fuel tank 30, and fuel can also be supplied from the main fuel tank 10 to the engine 203 of the fixed-wing UAV 200 via the anti-bubble fuel tank 30.

[0142] The anti-bubble oil tank 30 may include a first anti-bubble oil tank 30A and a second anti-bubble oil tank 30B. The first anti-bubble oil tank 30A may be fluidly connected to the first main oil tank 10A, while the second anti-bubble oil tank 30B may be fluidly connected to the second main oil tank 10B.

[0143] like Figure 3As shown, the engine 203 of the fixed-wing UAV 200 may include a first engine 203A and a second engine 203B, which can be respectively mounted below the first wing 201A and the second wing 201B. The engine 203 can be any type of engine that uses fuel, such as a fuel-powered turbojet engine or a turbofan engine. Multiple first engines 203A and multiple second engines 203B may be included, for example... Figure 3 and 25 As shown in the image.

[0144] An engine oil pump 60 may be disposed between the engine 203 and the anti-bubbling fuel tank 30 for supplying fuel to the engine 203. Specifically, as shown in the figure, the engine oil pump 60 may include a first engine oil pump 60A and a second engine oil pump 60B to supply fuel to the first engine 203A and the second engine 203B, respectively.

[0145] In addition, such as Figure 3 As shown, the UAV fuel system may also include a flow meter 40, which is fluidly connected between the anti-bubble fuel tank 30 and the engine 203 of the fixed-wing UAV 200 to measure the amount of fuel supplied to the engine 203, and may be connected to the onboard control system to send the measurement data to electronic devices such as controllers or memory.

[0146] As an example, flow meter 40 can record fuel consumption in real time. Thus, if the total weight of the fixed-wing UAV 200 is recorded before engine ignition, subtracting the fuel consumption allows for the calculation of the real-time weight of the fixed-wing UAV 200, which can then be used to... Figure 2 By interpolating the fuel consumption center of gravity curve in real time, the real-time center of gravity position of the fixed-wing UAV 200 can be obtained.

[0147] Therefore, according to the UAV fuel system 100 of the present invention, by conducting ground fuel consumption tests, calibrating the fuel flow meter, and measuring the fuel consumption curve, the weight and center of gravity of the aircraft can be calculated in real time.

[0148] The specific structure of the main fuel tank 10 and the auxiliary fuel tank 20 will be described in more detail below with reference to the accompanying drawings.

[0149] exist Figure 6-16 In this text, the first main fuel tank 10A is used as an example to describe the main fuel tank 10. The second main fuel tank 10B can be arranged symmetrically with the first main fuel tank 10A. Therefore, the following description can also be applied to the second main fuel tank 10B.

[0150] Figure 6 A schematic perspective view of the main fuel tank 10 according to a non-limiting embodiment of the present invention is shown; while Figure 7 Shown in different views Figure 6 The main fuel tank 10 is shown.

[0151] As shown in the figure, the shape of the main fuel tank 10 can be similar to that of an aircraft wing, and can include an inner section 101 close to the fuselage 202 and an outer section 102 away from the fuselage 202. The inner section 101 can be roughly rectangular, while the outer section 102 can taper toward the wingtip, and the height of the inner section 101 can be greater than that of the outer section 102.

[0152] The main fuel tank 10 may include multiple openings. For example... Figure 6 and 7 The diagram shows a first opening 11, a second opening 12, and a third opening 13. The first opening 11 and the third opening 13 can be located on the inner segment 101, while the second opening 12 can be located on the outer segment 102, for example, at the outermost part of the outer segment 102. Figure 7 As shown in the side view, the second opening 12 is at the highest point of the part of the main tank 10 that is tilted upwards.

[0153] Preferably, the first opening 11 can be located on the side of the inner section 101 and serve as a fuel inlet. The second opening 12 can be located at the very end of the outer section 102, while the third opening 13 can be located at the top of the inner section 101. The second opening 12 and the third opening 13 can be openings at the highest points of the main fuel tank 10 and can connect to the auxiliary fuel tank 20. In this way, the first opening 11 can be used as a low-level opening, while the second opening 12 and the third opening 13 can be used as high-level openings.

[0154] It should be understood that, as used herein, the terms "lower opening" and "higher opening" refer to the relative positional relationship of these openings. The "lower opening" may be connected via a fuel line or counterweight to a lower compartment within the fuel tank, while the "higher opening" may be a localized higher point within the fuel tank. During the process of adding fuel to the tank, fuel is added through the "lower opening," and air or fuel exits the tank through the "higher opening." During the process of supplying fuel to the engine, the "lower opening" and "higher opening" may have opposite functions. For example, during fuel supply, fuel or air may enter the tank through the "higher opening," and fuel may exit the tank and enter the engine through the "lower opening."

[0155] exist Figure 6 and 7 In the example shown, when refueling the main fuel tank 10, fuel can be injected into the main fuel tank 10 through the first opening 11. As the fuel level rises, air is gradually discharged from the second opening 12 and the third opening 13 of the main fuel tank 10 until the main fuel tank 10 is full.

[0156] Figure 8 It shows Figure 6 The top view of the main fuel tank 10 shown; and Figure 9 and Figure 11-14 It shows crossing Figure 8 A sectional view taken from different section lines in the image.

[0157] like Figure 8 As shown, the main fuel tank 10 may include a first opening 11, a second opening 12 and a third opening 13, as well as a first wave deflector 51. Figure 8 The diagram includes cross-sectional lines AA, BB, CC, DD, and EE to show the detailed structure of the main fuel tank 10.

[0158] Figure 9 It shows crossing Figure 8 The sectional view of section line AA in the middle, and Figure 10 A schematic diagram of a wave deflector 50 according to a non-limiting embodiment of the present invention is shown.

[0159] As shown in the figure, the first baffle 51 of the main oil tank 10, as an embodiment of the baffle 50, is positioned in the main oil tank 10. An oil passage hole 50A is provided on the circumferential edge of the first baffle 51, and the diameter R1 of the oil passage hole 50A of the first baffle 51 is equal to the length of the long side of the first baffle 51 (i.e.,...). Figure 9 The length of the longitudinal side (L1) is 4% to 8%.

[0160] The thickness of the first wave deflector 51 is approximately 2–5 mm, and preferably, the upper and lower edges of the first wave deflector 51 are designed with an airfoil shape. This effectively prevents the adverse effects of fuel sloshing on the center of gravity during aircraft maneuvers.

[0161] Figure 11-13 It shows crossing Figure 8 The cross-sectional views taken by different section lines BB, CC, and DD show the specific structures of the first opening 11, the second opening 12, and the third opening 13, respectively.

[0162] As can be seen, fluid connectors are provided at these openings. These fluid connectors can be sealed to the housing of the main fuel tank 10 by means of fasteners and gaskets, so as to allow fuel or air to enter or leave the main fuel tank 10 through these openings.

[0163] Figure 14 It shows crossing Figure 8 The cross-sectional view is taken by section line EE. In this view, a schematic structure of the first counterweight 11B is shown, which can ensure that the free end of the first inner pipeline 11A connected to the first opening 11 can be kept below the liquid level of the main oil tank 10, or at a substantially lowest position.

[0164] Figure 15 It shows Figure 6 Another top view of the main fuel tank 10 shown; and Figure 16 It shows crossing Figure 15 The sectional view is taken by the section line FF in the diagram.

[0165] As shown in the figure, the first inner pipeline 11A extends between the first opening 11 and the first counterweight 11B to supply fuel to the main fuel tank 10, thereby avoiding the generation of air bubbles, or to extract the fuel located at the bottom of the main fuel tank 10, thereby emptying the main fuel tank 10 as much as possible.

[0166] Figure 17 A schematic perspective view of an auxiliary fuel tank 20 according to a non-limiting embodiment of the present invention is shown; while Figure 18 Shown in different views Figure 17 The auxiliary fuel tank 20 is shown.

[0167] As shown in the figure, the shape of the auxiliary fuel tank 20 can be similar to that of the fuselage 202, and it is also similar to the fuselage 202. The auxiliary fuel tank 20 maintains the multi-segment arc feature.

[0168] The auxiliary fuel tank 20 may include multiple openings. For example... Figure 17 and 18 The fourth opening 21, the fifth opening 22, and the sixth opening 23 are shown in the figure. A platform portion 24 may be provided on the top of the auxiliary fuel tank 20, and a protrusion 24A may be provided on the platform portion 24.

[0169] The fourth opening 21 and the fifth opening 22 may be located on the side of the auxiliary fuel tank 20 (e.g., the front side facing the main fuel tank 10), while the sixth opening 23 may be located on the platform section 24 and serve as a fuel inlet.

[0170] The fourth opening 21 and the fifth opening 22 can be used as low-level openings and connected via fuel lines or a counterweight to a lower receiving space in the fuel tank to refuel the auxiliary fuel tank 20 with fuel from the first main fuel tank 10A and the second main fuel tank 10B, for example, via the second opening 12 and the third opening 13 of the main fuel tank 10 and the corresponding external lines. The sixth opening 23 can be an opening at the highest point of the auxiliary fuel tank 20 and can be used as a high-level opening.

[0171] During the process of adding fuel to the fuel tank, fuel is added to the auxiliary fuel tank 20 through the fourth opening 21 and the fifth opening 22, and air exits the auxiliary fuel tank 20 through the sixth opening 23. During the process of supplying fuel to the engine, the "low-level opening" and the "high-level opening" can have opposite effects. For example, during fuel supply, air can enter the fuel tank through the sixth opening 23, and fuel can exit the auxiliary fuel tank 20 and enter the engine through the fourth opening 21 and the fifth opening 22, for example, via the first main fuel tank 10A and the second main fuel tank 10B.

[0172] When refueling the auxiliary fuel tank 20, fuel can be injected into the auxiliary fuel tank 20 through the fourth opening 21 and the fifth opening 22. As the fuel level rises, air is gradually discharged from the sixth opening 23 of the auxiliary fuel tank 20 until the auxiliary fuel tank 20 is full.

[0173] Figure 19 It shows Figure 17 Another schematic perspective view of the auxiliary fuel tank 20 shown; Figure 20 It shows Figure 19 A top view; and Figure 21 and Figure 23-24 It shows crossing Figure 20 A sectional view taken from different section lines in the image.

[0174] like Figure 19 As shown, the auxiliary fuel tank 20 includes a fourth opening 21, a fifth opening 22 and a sixth opening 23, as well as a second wave deflector 52. Figure 20 The diagram includes cross-sectional lines GG, HH, and II to show the detailed structure of the auxiliary fuel tank 20, respectively.

[0175] Figure 21 It shows crossing Figure 20 The cross-sectional view of section line GG in the middle, and Figure 22 A schematic diagram of another wave deflector 50 according to a non-limiting embodiment of the present invention is shown.

[0176] As shown in the figure, a second wave deflector 52, as an embodiment of the wave deflector 50, is positioned within the auxiliary fuel tank 20. For example, the second wave deflector 52 can be arranged along the heading direction F, dividing the auxiliary fuel tank 20 into two symmetrical parts. An oil passage hole 50A is provided on the circumferential edge of the second wave deflector 52, and the diameter R2 of the oil passage hole 50A of the second wave deflector 52 is equal to the length of the long side of the second wave deflector 52 (i.e.,...). Figure 22 The length of the longitudinal side (L2) is 4% to 8%. Similarly, the thickness of the second wave deflector 52 can be approximately 2 to 5 mm.

[0177] Figure 23-24 It shows crossing Figure 20 The cross-sectional views taken by different section lines HH and II show the specific structures of the fifth opening 22 and the third counterweight 22A, respectively.

[0178] As can be seen, a fluid connector is provided at the fifth opening 22. The fluid connector can be sealed to the housing of the auxiliary fuel tank 20 by means of fasteners and gaskets, so as to allow fuel or air to enter or leave the auxiliary fuel tank 20 through the fifth opening 22.

[0179] like Figure 24As shown, the third counterweight 22A can ensure that the free end of the third inner pipeline 22A connected to the fifth opening 22 is kept below the liquid level in the auxiliary oil tank 20, or at the lowest position.

[0180] The third inner line 22A extends between the fifth opening 22 and the third counterweight 22A to supply fuel to the auxiliary fuel tank 20 while avoiding the generation of air bubbles, or to extract fuel located at the bottom of the auxiliary fuel tank 20, thereby emptying the auxiliary fuel tank 20 as much as possible.

[0181] Figure 25 A schematic diagram of a drone fuel system 100 according to a non-limiting embodiment of the present invention is shown.

[0182] Figure 25 The description takes a 200kg UAV fuel system 100 as an example. The UAV fuel system 100 can adopt a configuration of three fuel tanks connected together: a left wing fuel tank, a right wing fuel tank, and an auxiliary fuel tank. It is made of Kevlar fiber cloth and wrapped with an electrostatic shielding copper mesh.

[0183] As described above, each fuel tank can be equipped with a baffle 50 with an oil passage 50A to minimize the impact of fuel on the center of gravity during operation. The auxiliary fuel tank 20 is connected to the two main fuel tanks 10 via two external fuel lines, forming a communicating vessel.

[0184] The various components or parts of the UAV fuel system 100 are connected by fuel lines, which may include 6mm (inner diameter) × 8mm (outer diameter) and 8mm × 10mm PTFE tubing, 6mm × 8mm PU tubing, and 4mm × 6mm flexible tubing, etc., and those skilled in the art can select other types of tubing as needed. The flow meter 40 and the engine oil pump 60 can be unidirectional, that is, fuel is only allowed to be supplied to the engine 203 in one direction via the flow meter 40 and the engine oil pump 60.

[0185] In addition, corresponding control valves, such as solenoid valves, can be installed at the corresponding openings of the UAV fuel system 100 to control the opening or closing of each opening, thereby achieving the desired fuel supply, fuel release or supply function. The structure of these valves is known in the art, so for the sake of brevity, it will not be described in detail here.

[0186] Combination Figure 3 and 25 As can be seen, the following operations can be performed when refueling the tank:

[0187] 1) Open the filler port 71 and switch valve 72 of the pipeline accessory 70, close the third port 33 (C port) of the anti-bubble oil tank 30, and open the sixth opening 23 (H port) of the auxiliary oil tank 20, which can be connected to the atmosphere, for example, via the downward-extending external pipeline shown in the attached figure.

[0188] 2) Aviation kerosene or diesel fuel is added through filler port 71 and injected into anti-bubble fuel tank 30 through the first port 31 (port A). As the fuel level rises, air is gradually discharged from the second port 32 (port B) of anti-bubble fuel tank 30 until anti-bubble fuel tank 30 is full of fuel;

[0189] 3) Then, fuel is injected into the main fuel tank 10 (i.e., the left wing fuel tank and the right wing fuel tank) through the first opening 11 (D port) of the main fuel tank 10. As the fuel level rises, air is gradually discharged from the second opening 12 and the third opening 13 (E port and F port) of the main fuel tank 10 until the main fuel tank 10 is full;

[0190] 4) Then, fuel is injected into the auxiliary fuel tank 20 through the fourth opening 21 and the fifth opening 22 (G port). As the fuel level rises, air is gradually discharged from the sixth opening 23 (H port) of the auxiliary fuel tank 20 until the auxiliary fuel tank 20 is full. At this time, fuel may be discharged from the sixth opening 23 (H port).

[0191] 5) Close the filler port 71 and the switch valve 72.

[0192] When draining fuel from the tank, the following steps can be taken:

[0193] 1) Open the filler port 71 and the switch valve 72, close the third port 33 (C port) of the anti-bubble oil tank 30, and open the sixth opening 23 (H port) of the auxiliary oil tank 20, which can be connected to the atmosphere;

[0194] 2) Connect the drain pipe to the drain port (i.e., filler port 71) and draw fuel through an external fuel pump. The drain process is the reverse of the filler process.

[0195] 3) After the oil is drained, the filler port 71 and the switch valve 72 can be closed.

[0196] During fuel supply, the following operations can be performed:

[0197] 1) Close the filler port 71 and the switch valve 72, open the third port 33 (C port) of the anti-bubble oil tank 30, and open the sixth port 23 (H port) of the auxiliary oil tank 20;

[0198] 2) Engine oil pump 60 pumps fuel from the fuel tank (e.g., main fuel tank 10) and supplies it to engine 203. The fuel passes through flow meters 40, such as the first flow meter 40A and the second flow meter 40B, allowing for the measurement of the weight of fuel consumed, based on ground calibration tests (see fuel consumption center of gravity curve). Figure 3 This allows for real-time calculation of the aircraft's center of gravity. Additionally, an oil filter 80, such as a first oil filter 80A and a second oil filter 80B, can be installed between the anti-bubble fuel tank 30 and the flow meter 40 to filter out any impurities that may be present in the fuel.

[0199] During fuel supply, since the main fuel tank 10 is not connected to the atmosphere, while the auxiliary fuel tank 20 is connected to the atmosphere through the sixth opening 23 and fuel is drawn from the auxiliary fuel tank 20 through the second counterweight 21B, the fuel in the auxiliary fuel tank 20 will be consumed first, and the fuel in the main fuel tank 10 will only be consumed after the fuel in the auxiliary fuel tank 20 has been basically consumed.

[0200] Therefore, although the engine oil pump 60 pumps fuel out of the tank (e.g., main tank 10) during the supply period, as the fuel leaves the main tank 10, a negative pressure is generated in the main tank 10, which forces the oil in the auxiliary tank 20 to flow into the main tank 10, effectively pumping the fuel out of the auxiliary tank 20.

[0201] It should be understood that the above combination Figure 3 and 25 The method steps shown are exemplary, and those skilled in the art can adjust the order of the method steps, add corresponding steps, or delete relevant steps without departing from the scope of the present invention.

[0202] Figure 26 Another example of a fixed-wing drone 200 that can be equipped with a drone fuel system 100 according to a non-limiting embodiment of the present invention is shown; while Figure 27 Another example of a fixed-wing drone 200 that can be equipped with a drone fuel system 100 according to a non-limiting embodiment of the present invention is shown.

[0203] As shown in the figure Figure 26 and 27 The fixed-wing UAV 200 shown in the image Figure 1 The fixed-wing UAV 200 shown may have different configurations, but all include a UAV fuel system 100 according to the present invention, and the UAV fuel system 100 includes a main fuel tank 10 and an auxiliary fuel tank 20. The difference lies in that... Figure 26 In the example, the auxiliary fuel tank 20 can be positioned behind the main fuel tank 10, and can supply fuel to the engine 203 via either the main fuel tank 10 or the auxiliary fuel tank 20, enabling it to achieve [the desired effect]. Figure 2 A similar fuel consumption centroid curve is shown.

[0204] exist Figure 27 In the example, the main fuel tank 10 can have different shapes, and the engine 203 can be supplied with fuel via either the main fuel tank 10 or the auxiliary fuel tank 20, enabling the connection with... Figure 2 A similar fuel consumption centroid curve is shown.

[0205] Alternatively, depending on whether the fuel in the main fuel tank 10 or the auxiliary fuel tank 20 is consumed first, or the front and rear arrangement of the main fuel tank 10 or the auxiliary fuel tank 20, Figure 26 Alternatively, the fuel consumption curve of the fixed-wing UAV 200 could point in the opposite direction. For example, as fuel is consumed, the total weight of the fixed-wing UAV 200 gradually decreases from approximately 200 kg to approximately 120 kg, while the center of gravity position correspondingly changes from approximately 30%-35% MAC to approximately 20%-25% MAC, and then changes again to approximately 30%-35% MAC. That is, the center of gravity position relative to the nose of the UAV 200A first changes from the rear to the front, and then changes back to the rear.

[0206] The foregoing example uses the wing fuel tank as the main fuel tank and the fuselage fuel tank as the auxiliary fuel tank. In alternative embodiments, the fuselage fuel tank can also be used as the main fuel tank and the wing fuel tank as the auxiliary fuel tank without departing from the scope of the invention.

[0207] The terms “lower” and “higher” used herein to indicate orientation or location, and “first” and “second” used to indicate sequence, are merely to enable those skilled in the art to better understand the concept of the invention as illustrated in the preferred embodiments, and are not intended to limit the invention. Unless otherwise stated, all sequences, orientations, or locations are used only to distinguish one element / component / structure from another element / section / structure, and do not indicate any particular order, sequence of operations, direction, or orientation unless otherwise stated. For example, in an alternative embodiment, “first main tank” could be “second main tank.”

[0208] As used herein, unless otherwise specified, the terms “approximately” and “about” are interpreted as indicating a value or range of values ​​plus or minus five percent, or a deviation of the shape and / or position from the value by plus or minus five percent.

[0209] In summary, the drone fuel system 100 according to embodiments of the present invention overcomes the shortcomings of the prior art and achieves the intended purpose of the invention.

[0210] While the UAV fueling system of the present invention has been described above with reference to preferred embodiments, those skilled in the art should recognize that the above examples are merely illustrative and should not be construed as limiting the invention. Therefore, various modifications and variations can be made to the invention within the spirit and scope of the claims, and all such modifications and variations will fall within the scope claimed by the claims.

Claims

1. A drone fueling system (100), comprising: The main fuel tank (10) is disposed in the wing (201) of the fixed-wing UAV (200); An auxiliary fuel tank (20) is disposed in the fuselage (202) of the fixed-wing UAV (200) and positioned spaced apart from the main fuel tank (10) in the heading direction (F), wherein the auxiliary fuel tank (20) is fluidly connected to the main fuel tank (10) and supplies fuel to the engine (203) of the fixed-wing UAV (200) via the main fuel tank (10); The main fuel tank (10) is not connected to the atmosphere, while the auxiliary fuel tank (20) is connected to the atmosphere. During fuel supply, the engine fuel pump (60) pumps fuel from the main fuel tank (10) and creates a negative pressure in the main fuel tank (10), forcing fuel from the auxiliary fuel tank (20) to flow into the main fuel tank (10), thus consuming the fuel in the auxiliary fuel tank (20) first. The main fuel tank (10) is located at 0% to 25% of the span of the wing (201), while the auxiliary fuel tank (20) is located at 40% to 70% of the length of the fuselage (202) starting from the nose (200A). This allows the center of gravity (X) of the fixed-wing UAV (200) to change between 23% MAC and 31% MAC as the fixed-wing UAV (200) goes from being fully fueled to being completely fueled.

2. The unmanned aerial vehicle fuel system (100) according to claim 1, characterized in that, The main fuel tank (10) is located between the front and rear spars of the wing (201) and includes an inner section (101) near the fuselage (202) and an outer section (102) away from the fuselage (202), wherein the inner section is located at 25% to 50% of the chord of the wing (201) and the outer section is located at 15% to 40% of the chord of the wing (201).

3. The unmanned aerial vehicle fuel system (100) according to claim 2, characterized in that, The main fuel tank (10) includes a first main fuel tank (10A) and a second main fuel tank (10B) arranged symmetrically about the fuselage (202), and the first main fuel tank (10A) is arranged against the second main fuel tank (10B) in the inner section (101) near the fuselage (202).

4. The unmanned aerial vehicle fuel system (100) according to claim 1, characterized in that, The external shape of the main fuel tank (10) conforms to the internal space of the wing (201), and / or The external shape of the auxiliary fuel tank (20) conforms to the internal space of the fuselage (202).

5. The unmanned aerial vehicle fuel system (100) according to any one of claims 1-4, characterized in that, The UAV fuel system also includes an anti-bubble fuel tank (30) which is fluidly connected to the main fuel tank (10), wherein fuel is added to the main fuel tank (10) via the anti-bubble fuel tank (30) and fuel is supplied from the main fuel tank (10) to the engine (203) of the fixed-wing UAV (200) via the anti-bubble fuel tank (30).

6. The unmanned aerial vehicle fuel system (100) according to claim 5, characterized in that, The UAV fuel system also includes a flow meter (40) which is fluidly connected between the anti-bubble fuel tank (30) and the engine (203) of the fixed-wing UAV (200).

7. The unmanned aerial vehicle fuel system (100) according to any one of claims 1-4, characterized in that, The main fuel tank (10) and the auxiliary fuel tank (20) are respectively provided with wave deflectors (50), which are arranged along the heading direction (F) and located at 40% to 50% of the span of the main fuel tank (10) and the auxiliary fuel tank (20).

8. The unmanned aerial vehicle fuel system (100) according to claim 7, characterized in that, The wave deflector (50) has an oil passage hole (50A) on its circumferential edge, and the diameter of the oil passage hole is 4% to 8% of the length of the long side of the wave deflector (50).

9. The unmanned aerial vehicle fuel system (100) according to any one of claims 1-4, characterized in that, The main oil tank (10) and the auxiliary oil tank (20) are respectively provided with a low-level opening and a high-level opening. The low-level opening is in fluid communication with the counterweight inside the main oil tank (10) and the auxiliary oil tank (20), while the high-level opening is located at the local highest point of the main oil tank (10) and the auxiliary oil tank (20).

10. A fixed-wing unmanned aerial vehicle (200) comprising an unmanned aerial vehicle fuel system (100) according to any one of claims 1-9.

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