Aircraft fuel supply system and its operating method

Abstract

A fuel supply system includes a central fuel tank, a left-wing fuel tank, a right-wing fuel tank, a left-wing fuel collector tank, and a right-wing fuel collector tank, which are respectively arranged on both sides of the central fuel tank. Among them, the fuel supply system further includes a left-wing main fuel pipeline and a right-wing main fuel pipeline. Two fuel supply pumps are respectively arranged on these two main fuel pipelines. A pressure relief valve is arranged at the outlet of one fuel supply pump, and the downstream of the pressure relief valve is connected to another fuel supply pump. This fuel supply pump is respectively connected to the suction ports in the fuel collector tank and the central fuel tank, and a pipeline valve is arranged between each suction port and this another fuel supply pump. This structure can achieve a simplified override fuel supply architecture, and can reduce the energy consumption, weight, and cost of the system. It also relates to an operation method of this fuel supply system.

Description

Technical Field

[0001] The present invention belongs to the field of aircraft design, and particularly relates to a fuel supply system for an aircraft, and also relates to related methods for aircraft fuel supply. Background Art

[0002] The fuel system is one of the important systems of an aircraft, which supplies fuel to the aircraft's engines and auxiliary power units (APUs) and ensures fuel supply safety. In addition, the fuel system also controls the fuel consumption sequence of each fuel tank to cooperate with the aircraft's load control and improve the economy of aircraft operation.

[0003] In the prior art, the main fuel supply methods for aircraft engines include direct fuel supply, override fuel supply, transfer fuel supply, etc. In terms of fuel transfer, there are methods such as transfer by electric pump, transfer by ejector pump, gravity transfer, and air-boosted transfer. Hereinafter, a fuel supply system combining override fuel supply and ejector transfer / gravity transfer will be mainly introduced.

[0004] For example, in a fuel supply system of a certain aircraft model, a main fuel pump is provided in the wing fuel tank, and an override pump is provided in the central fuel tank. Among them, the override pump has a greater fuel pressurization ability than the main fuel pump, so as to be able to preferentially consume the fuel in the central fuel tank.

[0005] In the fuel supply system of another aircraft model, an override architecture is adopted for fuel supply to the engine, in which an override pump is provided in the central fuel tank to override the main fuel pumps in the wing fuel tanks located on both wings of the aircraft. In addition, fuel is transferred from the central fuel tank to the collector tank by means of ejector transfer. Among them, when the fuel quantity (oil level) in the central fuel tank drops to the situation where the override pump is closed, fuel is transferred from the central fuel tank to the wing fuel tank. In addition, fuel is transferred from the wing fuel tank to the collector tank by means of gravity transfer.

[0006] In applications, it is noted that there are some problems in the existing fuel supply systems. In order to provide a margin for the system, two fuel pumps are provided in each fuel tank, that is, two fuel pumps are provided in each of the left wing fuel tank, the right wing fuel tank and the central fuel tank, for a total of six fuel pumps. As a result, the number of high-power electrical equipment in the fuel supply system is relatively large, the energy consumption increases, and the weight of the system is also relatively large.

[0007] Secondly, in the case of adopting override fuel supply, the performance of the override pump in the central fuel tank needs to be higher than that of the fuel pumps in the wing fuel tanks, so that the override pump is actually "over-designed", which will cause the aircraft to carry a greater weight and also cause energy waste. Moreover, in the override fuel supply architecture, an override pump in the central fuel tank needs to be able to override two or more main fuel pumps in the wing fuel tanks in many cases, and it is relatively difficult to match the performance of the override pump with that of the main fuel pumps.

[0008] Again, for an aircraft with a three-tank layout, the central tank has a very high fuel capacity. It is desired to preferentially use the fuel in the central tank, so an override pump is used for override fuel supply. However, the use of this override pump will cause long-term additional energy consumption of the main fuel pump in the wing tank.

[0009] Therefore, it is necessary to further improve the fuel supply system of the aircraft to overcome the above-mentioned technical problems existing in the existing system. SUMMARY OF THE INVENTION

[0010] The present invention is made to solve the problems of the prior art described above. The object of the present invention is to provide an improved fuel supply system for an aircraft, which can simplify the architecture of the override fuel supply system, reduce energy consumption, and reduce the difficulty of performance matching between devices.

[0011] The present invention provides a fuel supply system, which includes a central tank, a left wing tank, a right wing tank, a left wing sump tank and a right wing sump tank respectively arranged on both sides of the central tank. Among them, the fuel supply system includes a left wing main fuel pipeline, on which a first left wing fuel pump and a second left wing fuel pump are connected. Among them, the first left wing fuel pump is arranged to extract fuel from the left wing sump tank, and the second left wing fuel pump is arranged to extract fuel from one of the left wing sump tank and the central tank. A first pressure relief valve is connected at the outlet of the first left wing fuel pump, and the second left wing fuel pump is connected downstream of the first left wing fuel pump. Similarly, the fuel supply system may also include a right wing main fuel pipeline, on which a first right wing fuel pump and a second right wing fuel pump are connected. The first right wing fuel pump is arranged to extract fuel from the right wing sump tank, and the second right wing fuel pump is arranged to extract fuel from one of the right wing sump tank and the central tank. A second pressure relief valve is connected at the outlet of the first right wing fuel pump, and the second right wing fuel pump is connected downstream of the first right wing fuel pump.

[0012] The fuel supply system with the above structure can achieve a simplified override fuel supply architecture, and the difficulty of performance matching between devices is also relatively low. In addition, this structure allows an override fuel supply to be achieved with a pump of lower power, thereby reducing the energy consumption of the system and helping to reduce the weight and cost of the system.

[0013] In a specific structure, the first left wing fuel pump is connected to a first left wing sump tank suction port arranged in the left wing sump tank, and the second left wing fuel pump is respectively connected to a second left wing sump tank suction port arranged in the left wing sump tank and a first central tank suction port arranged in the central tank. Among them, a first left wing cut-off valve is arranged between the second left wing fuel pump and the first central tank suction port, and a second left wing cut-off valve is arranged between the second left wing fuel pump and the second left wing sump tank suction port.

[0014] Similarly, the first right-wing fuel supply pump is connected to the first right-wing fuel tank suction port provided in the right-wing fuel tank assembly, and the second right-wing fuel supply pump is respectively connected to the second right-wing fuel tank suction port provided in the right-wing fuel tank assembly and the second central fuel tank suction port provided in the central fuel tank. Among them, a first right-wing cut-off valve is provided between the second right-wing fuel supply pump and the second central fuel tank suction port, and a second right-wing cut-off valve is provided between the second right-wing fuel supply pump and the second right-wing fuel tank suction port.

[0015] Preferably, the control device of the fuel supply system can at least control: the second left-wing fuel supply pump draws fuel from one of the second left-wing fuel tank suction port and the first central fuel tank suction port; and / or the second right-wing fuel supply pump draws fuel from one of the second right-wing fuel tank suction port and the second central fuel tank suction port.

[0016] Preferably, a first semi-sealed rib is provided in the left-wing fuel tank, and the part of the left-wing fuel tank on the side close to the central fuel tank of the first semi-sealed rib forms the left-wing fuel tank assembly. Similarly, a second semi-sealed rib is provided in the right-wing fuel tank, and the part of the right-wing fuel tank on the side close to the central fuel tank of the second semi-sealed rib forms the right-wing fuel tank assembly. Thus, the left-wing and right-wing fuel tank assemblies are integrally formed in the left-wing and right-wing fuel tanks, which is beneficial to improving the integration of the system.

[0017] Preferably, a left-wing rib one-way valve is provided at the lower part of the first semi-sealed rib, and at least one first hole is provided at the upper part of the first semi-sealed rib. Similarly, a right-wing rib one-way valve is provided at the lower part of the second semi-sealed rib, and at least one second hole is provided at the upper part of the second semi-sealed rib.

[0018] Preferably, a left-wing transfer pipeline is provided between the left-wing fuel tank assembly and the part of the left-wing fuel tank outside the left-wing fuel tank assembly, and a left-wing transfer ejector pump is provided in the left-wing transfer pipeline for transferring fuel from the part of the left-wing fuel tank outside the left-wing fuel tank assembly to the left-wing fuel tank assembly. A right-wing transfer pipeline is provided between the right-wing fuel tank assembly and the part of the right-wing fuel tank outside the left-wing fuel tank assembly, and a right-wing transfer ejector pump is provided in the right-wing transfer pipeline for transferring fuel from the part of the right-wing fuel tank outside the right-wing fuel tank assembly to the right-wing fuel tank assembly.

[0019] Preferably, a first one-way valve is provided between the first left-wing fuel supply pump and the second left-wing fuel supply pump, and the first one-way valve is arranged such that fuel can flow from the first left-wing fuel supply pump towards the second left-wing fuel supply pump, but prevents fuel from flowing along the direction from the second left-wing fuel supply pump to the first left-wing fuel supply pump. A second one-way valve is provided between the first right-wing fuel supply pump and the second right-wing fuel supply pump, and the second one-way valve is arranged such that fuel can flow from the first right-wing fuel supply pump towards the second right-wing fuel supply pump, but prevents fuel from flowing along the direction from the second right-wing fuel supply pump to the first left-wing fuel supply pump.

[0020] For the installation positions of the first left-wing fuel supply pump and the second left-wing fuel supply pump, they can be installed in the left-wing fuel tank assembly or in the central fuel tank. Similarly, the first right-wing fuel supply pump and the second right-wing fuel supply pump can also be installed in the right-wing fuel tank assembly or in the central fuel tank.

[0021] In one embodiment, the first left-wing fuel supply pump is the left-wing main fuel pump and the second left-wing fuel supply pump is the left-wing override pump. Thus, in this structure, the left-wing override pump can override the left-wing main fuel pump. Similarly, the first right-wing fuel supply pump is the right-wing main fuel pump and the second right-wing fuel supply pump is the right-wing override pump.

[0022] In another embodiment, a left-wing branch pipeline is connected to the outlet of the first left-wing fuel supply pump, a first pressure relief valve is arranged at the end of the left-wing branch pipeline, and a first pressure relief cut-off valve is arranged in the left-wing branch pipeline. In this structure, the second left-wing fuel supply pump can be the same pump as the first left-wing fuel supply pump, without the need to use a higher-power override pump, thus helping to further reduce energy consumption and costs. Similarly, a right-wing branch pipeline is connected to the outlet of the first right-wing fuel supply pump, a second pressure relief valve is arranged at the end of the right-wing branch pipeline, and a second pressure relief cut-off valve is arranged in the right-wing branch pipeline.

[0023] Preferably, a connecting pipeline is arranged between the left-wing main fuel pipeline and the right-wing main fuel pipeline, and a connecting pipeline cut-off valve is arranged on the connecting pipeline. Through the arrangement of the connecting pipeline and the connecting pipeline cut-off valve, cross-feed fuel supply can be achieved, that is, the left-wing fuel supply pump supplies fuel to the right-wing engine, or the right-wing fuel supply pump supplies fuel to the left-wing engine. Or, it is also possible to achieve that the left-wing fuel supply pump and the right-wing fuel supply pump supply fuel to only one of the left-wing engine and the right-wing engine together.

[0024] A method for operating the above fuel supply system is also designed. The method includes: the control device controls the first left-wing cut-off valve and the second left-wing cut-off valve, wherein when the first left-wing cut-off valve is opened, the second left-wing cut-off valve is closed, so that the second left-wing fuel supply pump only draws fuel from the central fuel tank; and when the first left-wing cut-off valve is closed, the second left-wing cut-off valve is opened, so that the second left-wing fuel supply pump only draws fuel from the left-wing fuel tank assembly.

[0025] The control device can also control the first right-wing cut-off valve and the second right-wing cut-off valve, wherein when the first right-wing cut-off valve is opened, the second right-wing cut-off valve is closed, so that the second right-wing fuel supply pump only draws fuel from the central fuel tank; and when the first right-wing cut-off valve is closed, the second right-wing cut-off valve is opened, so that the second right-wing fuel supply pump only draws fuel from the right-wing fuel tank assembly.

[0026] Further, in this method, the control device sets a first preset value, a second preset value, and a third preset value. Among them, for the left-wing fuel tank, when the fuel quantity in the central fuel tank drops to the first preset value, the second left-wing cut-off valve is opened and the first left-wing cut-off valve is closed, so as to consume the fuel in the left-wing fuel tank; when the fuel quantity in the left-wing fuel tank drops to the second preset value, the second left-wing cut-off valve is closed and the first left-wing cut-off valve is opened, so as to consume the fuel in the central fuel tank; and when the fuel quantity in the central fuel tank drops to the third preset value, the second left-wing cut-off valve is opened and the first left-wing cut-off valve is closed, so as to continue consuming the fuel in the left-wing fuel tank.

[0027] For the right-wing fuel tank, when the fuel quantity in the central fuel tank drops to the first preset value, the second right-wing cut-off valve is opened and the first right-wing cut-off valve is closed, so as to consume the fuel in the right-wing fuel tank; when the fuel quantity in the right-wing fuel tank drops to the second preset value, the second right-wing cut-off valve is closed and the first right-wing cut-off valve is opened, so as to consume the fuel in the central fuel tank; and when the fuel quantity in the central fuel tank drops to the third preset value, the second right-wing cut-off valve is opened and the first right-wing cut-off valve is closed, so as to continue consuming the fuel in the right-wing fuel tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The specific implementation manners of the present invention can be more clearly understood from the structures shown in the drawings. Among them, in the drawings:

[0029] Figure 1 The structural schematic diagram of the fuel supply system according to the first embodiment of the present invention is shown.

[0030] Figure 2 The structural schematic diagram of the fuel supply system according to the second embodiment of the present invention is shown.

[0031] Figure 3 The structural schematic diagram of the fuel supply system according to the third embodiment of the present invention is shown.

[0032] (Symbol Description)

[0033] 100 Fuel supply system

[0034] 110 Central fuel tank

[0035] 111 First central fuel tank suction port

[0036] 112 Second central fuel tank suction port

[0037] 113 First left-wing override pump cut-off valve

[0038] 114 First right-wing override pump cut-off valve

[0039] 115 Connecting pipe cut-off valve

[0040] 120 Left-wing fuel tank

[0041] 121 First half-sealed rib

[0042] 122 Left-wing fuel collecting tank

[0043] 123 Left-wing transfer ejector pump

[0044] 124 Left-wing transfer non-return valve

[0045] 125 First left-wing fuel collecting tank oil suction port

[0046] 126 Second left-wing fuel collecting tank oil suction port

[0047] 127 Second left-wing override pump cut-off valve

[0048] 130 Right-wing fuel tank

[0049] 131 Second half-sealed rib

[0050] 132 Right-wing fuel collecting tank

[0051] 133 Right-wing transfer ejector pump

[0052] 134 Right-wing transfer non-return valve

[0053] 135 First right-wing fuel collecting tank oil suction port

[0054] 136 Second right-wing fuel collecting tank oil suction port

[0055] 137 Second right-wing override pump cut-off valve

[0056] 141 Left-wing engine

[0057] 142 Right-wing engine

[0058] 151 Left-wing main fuel pipeline

[0059] 152 Right-wing main fuel pipeline

[0060] 153 Left-wing transfer pipeline

[0061] 154 Right-wing transfer pipeline

[0062] 155 Connecting pipeline

[0063] 161 Left-wing main oil pump

[0064] 162 Left-wing override pump

[0065] 163 First pressure relief valve

[0066] 164 First main oil pump non-return valve

[0067] 171 Right-wing main oil pump

[0068] 172 Right-wing override pump

[0069] 173 Second pressure relief valve

[0070] 174 Second main oil pump check valve

[0071] 200 Fuel supply system

[0072] 210 Central fuel tank

[0073] 211 First central fuel tank suction port

[0074] 212 Second central fuel tank suction port

[0075] 213 First left wing override pump cut-off valve

[0076] 214 First right wing override pump cut-off valve

[0077] 220 Left wing fuel tank

[0078] 221 First semi-sealed rib

[0079] 222 Left wing collecting fuel tank

[0080] 225 First left wing collecting fuel tank suction port

[0081] 226 Second left wing collecting fuel tank suction port

[0082] 227 Second left wing override pump cut-off valve

[0083] 230 Right wing fuel tank

[0084] 231 Second semi-sealed rib

[0085] 232 Right wing collecting fuel tank

[0086] 235 First right wing collecting fuel tank suction port

[0087] 236 Second right wing collecting fuel tank suction port

[0088] 237 Second right wing override pump cut-off valve

[0089] 241 Left wing engine

[0090] 242 Right wing engine

[0091] 261 Left wing main oil pump

[0092] 262 Left wing override pump

[0093] 263 First pressure relief valve

[0094] 264 First main oil pump check valve

[0095] 271 Right wing main oil pump

[0096] 272 Right-wing override pump

[0097] 273 Second pressure relief valve

[0098] 274 Second main oil pump check valve

[0099] 300 Fuel supply system

[0100] 310 Central fuel tank

[0101] 311 First central fuel tank suction port

[0102] 312 Second central fuel tank suction port

[0103] 313 First left-wing cut-off valve

[0104] 314 First right-wing cut-off valve

[0105] 320 Left-wing fuel tank

[0106] 321 First semi-sealed rib

[0107] 322 Left-wing sump tank

[0108] 325 First left-wing sump tank suction port

[0109] 326 Second left-wing sump tank suction port

[0110] 327 Second left-wing cut-off valve

[0111] 330 Right-wing fuel tank

[0112] 331 Second semi-sealed rib

[0113] 332 Right-wing sump tank

[0114] 335 First right-wing sump tank suction port

[0115] 336 Second right-wing sump tank suction port

[0116] 337 Second right-wing cut-off valve

[0117] 341 Left-wing engine

[0118] 342 Right-wing engine

[0119] 351 Left-wing fuel pipeline

[0120] 352 Right-wing fuel pipeline

[0121] 353 Left-wing branch pipeline

[0122] 354 Right-wing branch pipeline

[0123] 361 First left-wing fuel supply pump

[0124] 362 Second Left-wing Fuel Supply Pump

[0125] 363 First Pressure Relief Valve

[0126] 365 First Pressure Relief Cut-off Valve

[0127] 371 First Right-wing Fuel Supply Pump

[0128] 372 Second Right-wing Fuel Supply Pump

[0129] 373 Second Pressure Relief Valve

[0130] 375 Second Pressure Application Cut-off Valve Detailed Embodiment

[0131] The detailed embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. It should be understood that what is shown in the drawings is only the preferred embodiments of the present invention, which do not constitute a limitation to the scope of the present invention. Those skilled in the art can make various obvious modifications, variations, equivalent replacements to the present invention based on the embodiments shown in the drawings, and on the premise of non-contradiction, the technical features in the following described different embodiments can be combined arbitrarily with each other, and all of these fall within the protection scope of the present invention.

[0132] <First Embodiment>

[0133] Figure 1 The schematic structure of the fuel supply system 100 of the first embodiment of the present invention is shown. The fuel supply system 100 includes a central fuel tank 110, and a left-wing fuel tank 120 and a right-wing fuel tank 130 located on both sides of the central fuel tank 110 respectively.

[0134] A first semi-sealed rib 121 is provided in the left-wing fuel tank 120, and the part of the left-wing fuel tank 120 on the side of the first semi-sealed rib 121 close to the central fuel tank 110 serves as the left-wing fuel collection tank 122. In other words, in the present invention, through the first semi-sealed rib 121 provided in the left-wing fuel tank 120, the left-wing fuel collection tank 122 integrated in the left-wing fuel tank 120 is formed.

[0135] In Figure 1 In the structure of the fuel supply system 100 shown, a left-wing main fuel pump 161 is provided in the left-wing fuel collection tank 122. The left-wing main fuel pump 161 is provided in the left-wing main fuel pipeline 151 and is also communicated with the first left-wing fuel collection tank suction port 125 provided in the left-wing fuel collection tank 122. In this way, the left-wing main fuel pump 161 can draw fuel from the left-wing fuel collection tank 122 and supply fuel to the left-wing engine 141 via the left-wing main fuel pipeline 151.

[0136] In the left-wing fuel tank sump 122, a left-wing override pump 162 is also provided. The left-wing override pump 162 is connected to the left-wing main fuel supply line 151 downstream of the left-wing main oil pump 161, and is also in communication with a second left-wing fuel tank sump suction port 126 provided in the left-wing fuel tank sump 122 and a first central fuel tank suction port 111 provided in the central fuel tank 110. Thus, it can extract fuel from the left-wing fuel tank sump 122 and the central fuel tank 110, and then supply the fuel to the left-wing engine 141 via the left-wing main fuel supply line 151.

[0137] A first left-wing override pump cut-off valve 113 is provided between the first central fuel tank suction port 111 and the left-wing override pump 162 to allow opening and closing of the suction of fuel by the left-wing override pump 162 from the first central fuel tank suction port 111. Similarly, a second left-wing override pump cut-off valve 127 is provided between the left-wing override pump suction port 126 and the left-wing override pump 162 to allow opening or closing of the suction of fuel by the left-wing override pump 162 from the second left-wing fuel tank sump suction port 126.

[0138] A first pressure relief valve 163 is provided at the outlet of the left-wing main oil pump 161. And, a first main oil pump check valve 164 is also provided between the left-wing main oil pump 161 and the left-wing override pump 162 to allow fuel to flow from the left-wing main oil pump 161 towards the left-wing override pump 162, but prevent fuel from flowing back from the left-wing override pump 162 towards the left-wing main oil pump 161. Through the cooperation of the first pressure relief valve 163 and the first main oil pump check valve 164, the left-wing override pump 162 can override the left-wing main oil pump 161.

[0139] Furthermore, a left-wing transfer line 153 is provided between the left-wing fuel tank sump 122 and the remaining part of the left-wing fuel tank 120 (i.e., the part outside the left-wing fuel tank sump 122) for transferring fuel from the left-wing fuel tank 120 to the left-wing fuel tank sump 122. A left-wing transfer ejector pump 123 and preferably a left-wing transfer check valve 124 are provided on the left-wing transfer line 153. The left-wing transfer ejector pump 123 is used to transfer fuel from the part of the left-wing fuel tank 120 outside the left-wing fuel tank sump 122 to the left-wing fuel tank sump 122. The left-wing transfer check valve 124 is arranged to allow fuel to flow from the outside of the left-wing fuel tank sump 122 into the left-wing fuel tank sump 122, but prevent fuel from flowing back from the left-wing fuel tank sump 122 into the part of the left-wing fuel tank 120 outside the left-wing fuel tank sump 122.

[0140] Preferably, the dynamic flow used during the operation of the left-wing transfer ejector pump 123 is an annular jet. Additionally, a left-wing rib one-way valve (not shown) is provided at the position below the first semi-sealing rib 121, preferably near the bottom of the left-wing fuel tank 120. This left-wing rib one-way valve allows fuel to flow from the part of the left-wing fuel tank 120 outside the left-wing collecting tank 122 into the left-wing collecting tank 122, but prevents fuel from flowing back. Moreover, at least one, preferably a plurality of first holes are provided at the upper part of the first semi-sealing rib 121, or near the top of the left-wing fuel tank 120. These first holes serve the functions of ventilation and oil overflow. Specifically, when the fuel level in the left-wing collecting tank 122 is higher than the holes, the fuel can overflow from the left-wing collecting tank 122 into the part of the left-wing fuel tank 120 outside the left-wing collecting tank 122 through these holes, and when the fuel level in the left-wing collecting tank 122 is lower than the holes, ventilation can be carried out through these holes.

[0141] The structure in the right-wing fuel tank 130 can be similar to the structure of the left-wing fuel tank 120. Specifically, a second semi-sealing rib 131 is provided in the right-wing fuel tank 130, and the part of the right-wing fuel tank 130 on the side close to the central fuel tank 110 of the second semi-sealing rib 131 serves as the right-wing collecting tank 132. In other words, in the present invention, the right-wing collecting tank 132 integrated in the right-wing fuel tank 130 is formed by the second semi-sealing rib 131 provided in the right-wing fuel tank 130.

[0142] A right-wing main oil pump 171 is provided in the right-wing collecting tank 132. The right-wing main oil pump 171 is provided in the right-wing main fuel pipeline 152 and is also connected to the first right-wing collecting tank oil suction port 135 provided in the right-wing collecting tank 132. In this way, the right-wing main oil pump 171 can extract fuel from the right-wing collecting tank 132 and supply fuel to the right-wing engine 142 via the right-wing main fuel pipeline 152.

[0143] A right-wing override pump 172 is also provided in the right-wing collecting tank 132. The right-wing override pump 172 is connected to the right-wing main fuel pipeline 152 downstream of the right-wing main oil pump 171 and is also connected to the second right-wing collecting tank oil suction port 136 provided in the right-wing collecting tank 132 and the second central fuel tank oil suction port 112 provided in the central fuel tank 110, so that it can extract fuel from the right-wing collecting tank 132 and the central fuel tank 110 and then supply fuel to the right-wing engine 142 via the right-wing main fuel pipeline 152.

[0144] A first right-wing override pump cut-off valve 114 is provided between the second central fuel tank suction port 112 and the right-wing override pump 172 to allow opening and closing of the suction of fuel by the right-wing override pump 172 from the second central fuel tank suction port 112. Similarly, a second right-wing override pump cut-off valve 137 is provided between the right-wing override pump suction port 136 and the right-wing override pump 172 to allow opening or closing of the suction of fuel by the left-wing override pump 162 from the second right-wing fuel sump suction port 136.

[0145] A second pressure relief valve 173 is provided at the outlet of the right-wing main fuel pump 171. Also, a second main fuel pump check valve 174 is provided between the right-wing main fuel pump 171 and the right-wing override pump 172 to allow fuel to flow from the right-wing main fuel pump 171 towards the right-wing override pump 172, but prevent fuel from flowing back from the right-wing override pump 172 towards the right-wing main fuel pump 171. Through the cooperation of the second pressure relief valve 173 and the second main fuel pump check valve 174, the right-wing override pump 172 can override the right-wing main fuel pump 171.

[0146] A right-wing transfer pipeline 154 is provided between the right-wing fuel sump 132 and the remaining part of the right-wing fuel tank 130 (i.e., the part outside the right-wing fuel sump 132) for transferring fuel from the right-wing fuel tank 130 to the right-wing fuel sump 132. A right-wing transfer ejector pump 133 and preferably a right-wing transfer check valve 134 are provided on the right-wing transfer pipeline 154. The right-wing transfer ejector pump 133 is used to transfer fuel from the part of the right-wing fuel tank 130 outside the right-wing fuel sump 132 to the right-wing fuel sump 132. The right-wing transfer check valve 134 is arranged to allow fuel to flow from the outside of the right-wing fuel sump 132 into the right-wing fuel sump 132, but prevent fuel from flowing back from the right-wing fuel sump 132 to the part of the right-wing fuel tank 130 outside the right-wing fuel sump 132.

[0147] The dynamic flow used when the right-wing transfer ejector pump 133 operates is preferably also an annular jet. Additionally, a right-wing rib check valve (not shown) is provided below the second semi-sealed rib 131, preferably near the bottom of the right-wing fuel tank 130. The right-wing rib check valve allows fuel to flow from the part of the right-wing fuel tank 130 outside the right-wing fuel sump 132 into the right-wing fuel sump 132, but prevents fuel from flowing back. Also, at least one, preferably a plurality of second holes are provided at the upper part of the second semi-sealed rib 131, or near the top of the right-wing fuel tank 130. These second holes function for ventilation and oil spillage, specifically having the same function as the first holes on the first semi-sealed rib 121.

[0148] A connecting pipeline 155 is connected between the left-wing main fuel pipeline 151 and the right-wing main fuel pipeline 152, and a connecting pipeline cut-off valve 115 is provided on the connecting pipeline 155. The connecting pipeline cut-off valve 115 can be used to control the enabling and stopping of cross-feed fuel supply, as will be specifically described below.

[0149] The following will describe Figure 1 The operating principle of the fuel supply system 100 of the structure shown, especially the override fuel supply principle therein:

[0150] Here, the left-wing fuel tank 120 is taken as an example for illustration. The operating principle of the right-wing fuel tank 130 is basically similar to that of the left-wing fuel tank 120. When the first pressure relief valve 163 is opened, the left-wing override pump 162 is started, so that the left-wing override pump 162 overrides the left-wing main fuel pump 161. During the override fuel supply process, only one of the first left-wing override pump cut-off valve 113 and the second left-wing override pump cut-off valve 127 is opened.

[0151] Among them, when it is determined that fuel needs to be pumped from the central fuel tank 110, the first left-wing override pump cut-off valve 113 is opened, and the second left-wing override pump cut-off valve 127 is closed, so that fuel can only be pumped from the first central fuel tank suction port 111.

[0152] On the other hand, when it is determined that fuel needs to be pumped from the left-wing fuel sump 122, the first left-wing override pump cut-off valve 113 is closed, and the second left-wing override pump cut-off valve 127 is opened, so that fuel can only be pumped from the second left-wing fuel sump suction port 126.

[0153] Furthermore, the above control is automatically controlled by a control device (not shown) such as a computer, without manual intervention. The control device controls the first left-wing override pump cut-off valve 113 and the second left-wing override pump cut-off valve 127 according to parameters such as the fuel quantity in the left-wing fuel tank 120, the fuel quantity in the central fuel tank 110, and the flight phase of the aircraft.

[0154] For example, in a control method based on the fuel levels in the central fuel tank 110 and the left-wing fuel tank 120 / right-wing fuel tank 130, considering that in order to extend the service life of the fuel pump / override pump, the fuel in the fuel tank is used to cool and dissipate heat from the fuel pump / override pump, it is necessary to retain a portion of the fuel in the fuel tank. Accordingly, a control device such as a computer sets a first preset value X1 representing the fuel level in the central fuel tank 110. When the fuel level in the central fuel tank 110 drops to the first preset value X1, the first left-wing override pump cut-off valve 113 / first right-wing override pump cut-off valve 114 is closed, and the second left-wing override pump cut-off valve 127 / second right-wing override pump cut-off valve 137 is opened, so that fuel is only drawn from the left-wing fuel sump 122 / right-wing fuel sump 132. Then, when the fuel level in the left-wing fuel tank 120 / right-wing fuel tank 130 drops to a second preset value X2, the first left-wing override pump cut-off valve 113 / first right-wing override pump cut-off valve 114 is opened, and the second left-wing override pump cut-off valve 127 / second right-wing override pump cut-off valve 137 is closed, so that fuel is only drawn from the central fuel tank 110. Then, when the fuel level in the central fuel tank 110 drops to a third preset value X3, the first left-wing override pump cut-off valve 113 / first right-wing override pump cut-off valve 114 is closed, and the second left-wing override pump cut-off valve 127 / second right-wing override pump cut-off valve 137 is opened, and fuel continues to be only drawn from the left-wing fuel sump 122 / right-wing fuel sump 132.

[0155] In addition, when crossfeed fuel supply is required, the connecting pipe cut-off valve 115 can be opened, so that crossfeed fuel supply can be achieved. For example, fuel can be supplied to the right-wing engine 142 through the left-wing main fuel pump 161 / left-wing override pump 162, or fuel can be supplied to the left-wing engine 141 through the right-wing main fuel pump 171 / right-wing override pump 172. Alternatively, fuel can be supplied to one of the left-wing engine 141 and the right-wing engine 142 by the left-wing main fuel pump 161 / left-wing override pump 162 and the right-wing main fuel pump 171 / right-wing override pump 172 together.

[0156] <Second Embodiment>

[0157] Figure 2 The fuel supply system 200 of the second embodiment of the present invention is shown. In the following description of the second embodiment, the technical features different from those of the first embodiment will be mainly described. Unless there is a contrary description or conflict with other technical features in the following content, the features described in the first embodiment are also applicable to the second embodiment and will not be described in detail herein.

[0158] Similar to the fuel supply system 100 of the first embodiment, the fuel supply system 200 includes a central fuel tank 210, and a left-wing fuel tank 220 and a right-wing fuel tank 230 respectively located on both sides of the central fuel tank 210.

[0159] A first semi-sealing rib 221 is provided in the left-wing fuel tank 220, and the portion of the left-wing fuel tank 220 on the side of the first semi-sealing rib 221 close to the central fuel tank 210 serves as the left-wing fuel collecting tank 222, which is the same as that in the first embodiment.

[0160] The fuel supply system 200 of the second embodiment also includes a left-wing main oil pump 261 and a left-wing override pump 262. Different from the first embodiment, the left-wing main oil pump 261 and the left-wing override pump 262 are provided in the central fuel tank 210. The left-wing main oil pump 261 is communicated with a first left-wing fuel collecting tank suction port 225 provided in the left-wing fuel collecting tank 222, so as to extract fuel from the left-wing fuel collecting tank 222. The left-wing override pump 262 is communicated with a first central fuel tank suction port 211 provided in the central fuel tank 210 and a second left-wing fuel collecting tank suction port 226 provided in the left-wing fuel collecting tank 222. Thus, the left-wing override pump 262 can extract fuel from the central fuel tank 210 and the left-wing fuel collecting tank 222 to supply fuel to the left-wing engine 241.

[0161] Similar to the first embodiment, a first left-wing override pump cut-off valve 213 is provided between the first central fuel tank suction port 211 and the left-wing override pump 262, and a second left-wing override pump cut-off valve 227 is provided between the second left-wing fuel collecting tank suction port 226 and the left-wing override pump 262.

[0162] Moreover, a first pressure relief valve 263 and a first main oil pump check valve 264 are provided at the outlet of the left-wing main oil pump 261. Among them, a pipeline leading to the left-wing fuel collecting tank 222 is connected to the first pressure relief valve 263, so that the fuel flowing out of the first pressure relief valve 263 can flow back to the left-wing fuel collecting tank. With the help of the first pressure relief valve 263 and the first main oil pump check valve 264, the left-wing override pump 262 can override the left-wing main oil pump 261.

[0163] Similar to the left-wing fuel tank 220, a second semi-sealing rib 231 is provided in the right-wing fuel tank 230, and the portion of the right-wing fuel tank 230 on the side of the second semi-sealing rib 231 close to the central fuel tank 210 serves as the right-wing fuel collecting tank 232.

[0164] The fuel supply system 200 also includes a right-wing main oil pump 271 and a right-wing override pump 272. The right-wing main oil pump 271 and the right-wing override pump 272 are provided in the central fuel tank 210. The right-wing main oil pump 271 is communicated with a first right-wing fuel collecting tank suction port 235 provided in the right-wing fuel collecting tank 232, so as to extract fuel from the right-wing fuel collecting tank 232. The right-wing override pump 272 is communicated with a second central fuel tank suction port 212 provided in the central fuel tank 210 and a second right-wing fuel collecting tank suction port 236 provided in the right-wing fuel collecting tank 232. Thus, the right-wing override pump 272 can extract fuel from the central fuel tank 210 and the right-wing fuel collecting tank 232 to supply fuel to the right-wing engine 242.

[0165] Moreover, a first right-wing override pump cut-off valve 214 is provided between the second central fuel tank suction port 212 and the right-wing override pump 272, and a second right-wing override pump cut-off valve 237 is provided between the second right-wing fuel collection tank suction port 236 and the right-wing override pump 272.

[0166] Moreover, a second pressure relief valve 273 and a second main oil pump check valve 274 are provided at the outlet of the right-wing main oil pump 271. Among them, a pipeline leading to the right-wing fuel collection tank 232 is connected to the second pressure relief valve 273, so that the fuel flowing out of the second pressure relief valve 273 can flow back to the right-wing fuel collection tank. With the help of the second pressure relief valve 273 and the second main oil pump check valve 274, the right-wing override pump 272 can override the right-wing main oil pump 271.

[0167] <Third Embodiment>

[0168] Figure 3 A fuel supply system 300 of the third embodiment of the present invention is shown. In the following description of the third embodiment, the technical features different from those of the first and second embodiments will be mainly described. Unless there is a contrary description or conflict with other technical features in the following content, the features described in the first and second embodiments are also applicable to the third embodiment, and will not be described in detail here.

[0169] A first semi-sealed rib 321 is provided in the left-wing fuel tank 320. The part of the left-wing fuel tank 320 on the side of the first semi-sealed rib 321 close to the central fuel tank 310 serves as the left-wing fuel collection tank 322, which is the same as that in the first embodiment.

[0170] A first left-wing fuel supply pump 361 and a second left-wing fuel supply pump 362 are provided in the left-wing fuel collection tank 322. The first left-wing fuel supply pump 361 is provided in the left-wing fuel pipeline 351 and is also communicated with the first left-wing fuel collection tank suction port 325 provided in the left-wing fuel collection tank 322. In this way, the first left-wing fuel supply pump 361 can extract fuel from the left-wing fuel collection tank 322 and supply fuel to the left-wing engine 341 via the left-wing fuel pipeline 351.

[0171] The second left-wing fuel supply pump 362 is used as an alternative to the left-wing override pumps 162 / 262 in the first and second embodiments. The second left-wing fuel supply pump 362 is connected to the left-wing fuel pipeline 351 and is also communicated with the second left-wing fuel collection tank suction port 326 provided in the left-wing fuel collection tank 322 and the first central fuel tank suction port 311 provided in the central fuel tank 110, so that it can extract fuel from the left-wing fuel collection tank 322 and the central fuel tank 310 and then supply fuel to the left-wing engine 341 via the left-wing main fuel pipeline 351.

[0172] A first left-wing cut-off valve 313 is provided between the first central fuel tank suction port 311 and the second left-wing fuel supply pump 362 to allow opening and closing of the suction of fuel by the second left-wing fuel supply pump 362 from the first central fuel tank suction port 311. Similarly, a second left-wing cut-off valve 327 is provided between the second left-wing fuel tank suction port 326 and the second left-wing fuel supply pump 362 to allow opening or closing of the suction of fuel by the second left-wing fuel supply pump 362 from the second left-wing fuel tank suction port 326.

[0173] In addition, different from the first and second embodiments, in the third embodiment, a left-wing branch pipeline 353 is provided at the outlet of the first left-wing fuel supply pump 361. One end of the left-wing branch pipeline 353 is connected to the left-wing fuel pipeline 351, and a first pressure relief valve 363 is provided at the other end. And a first pressure relief cut-off valve 365 is provided on the left-wing fuel pipeline 351.

[0174] A second semi-sealed rib 331 is provided in the right-wing fuel tank 330, and the part of the right-wing fuel tank 330 on the side close to the central fuel tank 310 of the second semi-sealed rib 331 serves as the right-wing fuel tank 332.

[0175] And, similar to the left-wing fuel tank 320, a first right-wing fuel supply pump 371 is also provided in the right-wing fuel tank 330. A second right-wing fuel supply pump 372 is also provided in the right-wing fuel tank 330 as an alternative to the right-wing override pumps 172 / 272 in the first and second embodiments. The first right-wing fuel supply pump 371 and the second right-wing fuel supply pump 372 are connected to the right-wing fuel pipeline 352 to supply fuel to the right-wing engine 342.

[0176] The fuel supply system 300 further includes components such as a first right-wing fuel tank suction port 335, a first right-wing cut-off valve 314, a second right-wing fuel tank suction port 336, a second right-wing cut-off valve 337, a second central fuel tank suction port 312, etc., and their structures and arrangements are the same as the corresponding components in the left-wing fuel tank 320.

[0177] A right-wing branch pipeline 354 is connected to the outlet of the first right-wing fuel supply pump 371, a second pressure relief valve 373 is provided at the end of the right-wing branch pipeline 354, and a second pressure application cut-off valve 375 is provided in the right-wing branch pipeline 354.

[0178] In the structure of the third embodiment, override fuel supply is achieved by opening and closing the first pressure relief cut-off valve 365 and the second pressure application cut-off valve 375. Specifically, when the first pressure relief cut-off valve 365 and the second pressure application cut-off valve 375 are closed, the working states of the first left-wing fuel supply pump 361 and the second left-wing fuel supply pump 362 are the same, and the working states of the first right-wing fuel supply pump 371 and the second right-wing fuel supply pump 372 are also the same. Therefore, the four fuel supply pumps supply fuel to the left-wing engine 341 and the right-wing engine 342 in the same working state.

[0179] When the first pressure relief cut-off valve 365 is opened, the first pressure relief valve 363 starts to operate, creating a pressure difference at the intersection of the fuel supply pipelines downstream of the first left-wing fuel supply pump 361 and the second left-wing fuel supply pump 362, so as to achieve the override fuel supply of the second left-wing fuel supply pump 362 to the first left-wing fuel supply pump 361. At the same time, the first left-wing cut-off valve 313 is opened and the second left-wing cut-off valve 327 is closed, thereby drawing fuel from the first central fuel tank suction port 311, that is, preferentially consuming the fuel in the central fuel tank 310.

[0180] Similarly, when the second pressure relief cut-off valve 375 is opened, the second pressure relief valve 373 starts to operate, creating a pressure difference at the intersection of the fuel supply pipelines downstream of the first right-wing fuel supply pump 371 and the second right-wing fuel supply pump 372, so as to achieve the override fuel supply of the second right-wing fuel supply pump 372 to the first right-wing fuel supply pump 371. At the same time, the first right-wing cut-off valve 314 is opened and the second right-wing cut-off valve 337 is closed, thereby drawing fuel from the second central fuel tank suction port 312, that is, preferentially consuming the fuel in the central fuel tank 310.

Claims

1. A fuel supply system, the fuel supply system comprising a central fuel tank, and a left-wing fuel tank and a right-wing fuel tank respectively arranged on both sides of the central fuel tank; It is characterized in that The fuel supply system further comprises: A left-wing collecting fuel tank, wherein a first semi-sealed rib is arranged in the left-wing fuel tank, and a part of the left-wing fuel tank on the side of the first semi-sealed rib close to the central fuel tank forms the left-wing collecting fuel tank; A right-wing collecting fuel tank, wherein a second semi-sealed rib is arranged in the right-wing fuel tank, and a part of the right-wing fuel tank on the side of the second semi-sealed rib close to the central fuel tank forms the right-wing collecting fuel tank; A left-wing main fuel pipeline, a first left-wing fuel supply pump and a second left-wing fuel supply pump are connected to the left-wing main fuel pipeline, wherein the first left-wing fuel supply pump is arranged to extract fuel from the left-wing collecting fuel tank, the second left-wing fuel supply pump is arranged to extract fuel from one of the left-wing collecting fuel tank and the central fuel tank, a first pressure relief valve is connected to the outlet of the first left-wing fuel supply pump, and the second left-wing fuel supply pump is connected downstream of the first left-wing fuel supply pump; and / or A right-wing main fuel pipeline, a first right-wing fuel supply pump and a second right-wing fuel supply pump are connected to the right-wing main fuel pipeline, the first right-wing fuel supply pump is arranged to extract fuel from the right-wing collecting fuel tank, the second right-wing fuel supply pump is arranged to extract fuel from one of the right-wing collecting fuel tank and the central fuel tank, a second pressure relief valve is connected to the outlet of the first right-wing fuel supply pump, and the second right-wing fuel supply pump is connected downstream of the first right-wing fuel supply pump.

2. The fuel supply system according to claim 1, wherein The first left-wing fuel supply pump is connected to a first left-wing collecting fuel tank suction port arranged in the left-wing collecting fuel tank, the second left-wing fuel supply pump is respectively connected to a second left-wing collecting fuel tank suction port arranged in the left-wing collecting fuel tank and a first central fuel tank suction port arranged in the central fuel tank, wherein a first left-wing cut-off valve is arranged between the second left-wing fuel supply pump and the first central fuel tank suction port, and a second left-wing cut-off valve is arranged between the second left-wing fuel supply pump and the second left-wing collecting fuel tank suction port; and / or The first right-wing fuel supply pump is connected to a first right-wing collecting fuel tank suction port arranged in the right-wing collecting fuel tank, the second right-wing fuel supply pump is respectively connected to a second right-wing collecting fuel tank suction port arranged in the right-wing collecting fuel tank and a second central fuel tank suction port arranged in the central fuel tank, wherein a first right-wing cut-off valve is arranged between the second right-wing fuel supply pump and the second central fuel tank suction port, and a second right-wing cut-off valve is arranged between the second right-wing fuel supply pump and the second right-wing collecting fuel tank suction port.

3. The fuel supply system according to claim 2, characterized in that, The fuel supply system further comprises a control device, and the control device can at least control: the second left-wing fuel supply pump extracts fuel from one of the second left-wing collecting fuel tank suction port and the first central fuel tank suction port; and / or the second right-wing fuel supply pump extracts fuel from one of the second right-wing collecting fuel tank suction port and the second central fuel tank suction port.

4. The fuel supply system according to claim 1, wherein A left-wing rib portion one-way valve is provided at the lower part of the first semi-sealing rib, and at least one first hole is provided at the upper part of the first semi-sealing rib; and / or A right-wing rib portion one-way valve is provided at the lower part of the second semi-sealing rib, and at least one second hole is provided at the upper part of the second semi-sealing rib.

5. The fuel supply system according to claim 1, wherein A left-wing transfer pipeline is provided between the left-wing fuel tank assembly and the part of the left-wing fuel tank outside the left-wing fuel tank assembly, and a left-wing transfer ejector pump is provided in the left-wing transfer pipeline for transferring fuel from the part of the left-wing fuel tank outside the left-wing fuel tank assembly to the left-wing fuel tank assembly; and / or A right-wing transfer pipeline is provided between the right-wing fuel tank assembly and the part of the right-wing fuel tank outside the left-wing fuel tank assembly, and a right-wing transfer ejector pump is provided in the right-wing transfer pipeline for transferring fuel from the part of the right-wing fuel tank outside the right-wing fuel tank assembly to the right-wing fuel tank assembly.

6. The fuel supply system according to claim 1, wherein A first one-way valve is provided between the first left-wing fuel pump and the second left-wing fuel pump, and the first one-way valve is arranged such that fuel can flow from the first left-wing fuel pump towards the second left-wing fuel pump, but prevents fuel from flowing in the direction from the second left-wing fuel pump to the first left-wing fuel pump; and / or A second one-way valve is provided between the first right-wing fuel pump and the second right-wing fuel pump, and the second one-way valve is arranged such that fuel can flow from the first right-wing fuel pump towards the second right-wing fuel pump, but prevents fuel from flowing in the direction from the second right-wing fuel pump to the first right-wing fuel pump.

7. The fuel supply system according to any one of claims 1 to 6, characterized in that, The first left-wing fuel pump and the second left-wing fuel pump are arranged in the left-wing fuel tank assembly or the central fuel tank; and / or The first right-wing fuel pump and the second right-wing fuel pump are arranged in the right-wing fuel tank assembly or the central fuel tank.

8. The fuel supply system according to any one of claims 1 to 6, characterized in that, The first left-wing fuel pump is a left-wing main fuel pump, and the second left-wing fuel pump is a left-wing override pump; and / or The first right-wing fuel pump is a right-wing main fuel pump, and the second right-wing fuel pump is a right-wing override pump.

9. The fuel supply system according to any one of claims 1 to 6, characterized in that A left-wing branch pipeline is connected to the outlet of the first left-wing fuel pump, a first pressure relief valve is provided at the end of the left-wing branch pipeline, and a first pressure relief cut-off valve is provided in the left-wing branch pipeline; and / or A right-wing branch pipeline is connected to the outlet of the first right-wing fuel pump, a second pressure relief valve is provided at the end of the right-wing branch pipeline, and a second pressure relief cut-off valve is provided in the right-wing branch pipeline.

10. The fuel supply system according to claim 1, characterized in that, A communication pipeline is provided between the left-wing main fuel pipeline and the right-wing main fuel pipeline, and a communication pipeline cut-off valve is provided on the communication pipeline.

11. A method of operating a fuel supply system as claimed in claim 3, characterized in that, The method includes: The control device controls the first left-wing cut-off valve and the second left-wing cut-off valve. When the first left-wing cut-off valve is open, the second left-wing cut-off valve is closed, so that the second left-wing fuel supply pump only draws fuel from the central fuel tank; when the first left-wing cut-off valve is closed, the second left-wing cut-off valve is open, so that the second left-wing fuel supply pump only draws fuel from the left-wing fuel sump tank; and / or The control device controls the first right-wing cut-off valve and the second right-wing cut-off valve. When the first right-wing cut-off valve is open, the second right-wing cut-off valve is closed, so that the second right-wing fuel supply pump only draws fuel from the central fuel tank; when the first right-wing cut-off valve is closed, the second right-wing cut-off valve is open, so that the second right-wing fuel supply pump only draws fuel from the right-wing fuel sump tank.

12. The operating method according to claim 11, characterized in that, It further includes: The control device sets a first preset value, a second preset value, and a third preset value. When the fuel quantity in the central fuel tank drops to the first preset value, the second left-wing cut-off valve is opened and the first left-wing cut-off valve is closed, so as to consume the fuel in the left-wing fuel tank; when the fuel quantity in the left-wing fuel tank drops to the second preset value, the second left-wing cut-off valve is closed and the first left-wing cut-off valve is opened, so as to consume the fuel in the central fuel tank; when the fuel quantity in the central fuel tank drops to the third preset value, the second left-wing cut-off valve is opened and the first left-wing cut-off valve is closed, so as to continue consuming the fuel in the left-wing fuel tank; and / or When the fuel quantity in the central fuel tank drops to the first preset value, the second right-wing cut-off valve is opened and the first right-wing cut-off valve is closed, so as to consume the fuel in the right-wing fuel tank; when the fuel quantity in the right-wing fuel tank drops to the second preset value, the second right-wing cut-off valve is closed and the first right-wing cut-off valve is opened, so as to consume the fuel in the central fuel tank; when the fuel quantity in the central fuel tank drops to the third preset value, the second right-wing cut-off valve is opened and the first right-wing cut-off valve is closed, so as to continue consuming the fuel in the right-wing fuel tank.

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