FUEL TANK FOR AN AIRCRAFT

Description

[0001] The invention relates to the field of fuel storage on board an aircraft. An aircraft generally comprises at least one fuel tank designed to store kerosene or liquid hydrogen, in particular to supply energy to a propulsion system of the aircraft. Such a tank is for example elongated in shape, for example cylindrical. A fuel pump is generally associated with the tank so as to allow the supply of fuel to a user system such as a propulsion engine or a fuel cell. For this, the fuel pump is connected at the inlet to a pipe, one free end of which is located in the lower part of the tank. When the aircraft is on the ground or when it is flying horizontally, the tank is generally in a horizontal position. As long as there is fuel left in the tank, the free end of the pipe is covered with fuel so that the pump does not risk sucking in air.However, in certain phases of aircraft flight, in particular during takeoff, landing or during aircraft maneuvers, the aircraft and the tank may be tilted. The free end of the hose may then not be covered with fuel and the pump may then suck in air, which should be avoided on the one hand to avoid damaging the pump and on the other hand to allow the continuity of the fuel supply to the user system.

[0002] Document US 2021 / 347252 A1 describes according to its abstract a suction system for a liquid reservoir, the reservoir being defined by side walls and a bottom wall, the system comprising a layer of permeable material, and the system comprises fixing means for fixing said permeable layer on at least one wall of said reservoir. The system also comprises means for suctioning said liquid arranged inside said permeable layer and means for connecting these suction means to a suction duct for suctioning said liquid. An internal volume is defined between said layer of permeable material, said fixing means and said at least one wall of said reservoir, the liquid being sucked into said internal volume through said layer of permeable material and said suction means. STATEMENT OF THE INVENTION:

[0003] The present invention aims in particular to provide a solution to this problem. It relates to an aircraft fuel tank according to claim 1.

[0004] Thus, when the first end of one of the pipes is not covered with fuel due to a tilt of the tank, the fuel level sensor associated with this pipe detects a low fuel level and the valve associated with this pipe is controlled in the closed position by the control system. This prevents air from being sucked in through the first end of the pipe. In addition, since the first ends of the different pipes are distributed over the lower part of the tank, as long as there is fuel left in the tank, the end of at least one of the pipes is covered with fuel. Consequently, the valve associated with this pipe is controlled in the open position by the control system, which ensures the continuity of fuel supply to a user system.

[0005] According to different embodiments which can be taken individually or in combination: the tank is elongated along a length of said tank and the set of pipes comprises at least four pipes including a first pipe whose first end is located near a first end of said length, a second pipe whose first end is located near a second end of the length, opposite the first end of said length, and two other pipes whose first ends are located on either side of the middle of the length of the tank. Advantageously, said first ends of the two other pipes are further located on either side of a longitudinal axis of the tank; the lower part of the tank is shaped so as to have a low point at the location of the first end of at least one of the pipes of the set of pipes; the tank comprises a partition partially covering the lower part of the tank and spaced from a lower wall of the tank in such a way that the first ends of the pipes as well as the level sensors are located between the lower wall of the tank and said partition. In particular, the partition is equipped with a valve provided to allow the evacuation towards an upper part of the tank, of gas contained between the lower wall of the tank and said partition; the tank comprises a set of walls each extending between the partition and the lower wall of the tank.In particular, the walls of the set of walls delimit sub-volumes of the tank between the partition and the lower wall of the tank, the number of sub-volumes being equal to the number of pipes of the set of pipes.

[0006] The invention also relates to an aircraft comprising such a tank. DETAILED DESCRIPTION:

[0007] The invention will be better understood by reading the following description and examining the attached figures. There figure 1 illustrates an aircraft equipped with a fuel tank. The figure 2 is a functional diagram of a fuel tank according to one embodiment of the invention. figure 3 is a detailed view of the lower part of the tank, illustrating a particular embodiment of the invention. The figure 4 , similar to the figure 2 , is a functional diagram of a fuel tank according to one embodiment of the invention.

[0008] Tank 10 shown on the figure 2 comprises a shell 20 intended to store fuel, in particular kerosene or hydrogen. When the fuel corresponds to hydrogen, it is for example stored in the liquid state in the tank 10, at a temperature less than or equal to -253°C. The tank 10 is then a so-called cryogenic tank of the double-shell type, comprising an inner shell and an outer shell between which a thermal insulator is arranged. The shell 20 shown in the figure 2 then corresponds to the internal shell of the tank. In the figure, the tank is shown in a position corresponding to that which it occupies when the aircraft is on the ground or when it is flying horizontally. A lower wall 22 of the tank shell is then horizontal or substantially horizontal.

[0009] The tank 10 comprises a set of pipes comprising at least two pipes 12a, 12d, a first end of each pipe being arranged in a lower part 28 of the tank, the first ends of the different pipes of the set of pipes being distributed over the lower part 28 of the tank.

[0010] The tank 10 also comprises a fuel pump 18 and a manifold 16 to which the second ends of the various pipes 12a, 12d of the set of pipes are connected at the inlet, an outlet of the manifold being connected to the fuel pump 18.

[0011] The tank 10 also comprises a set of fuel level sensors 14a, 14d. A fuel level sensor is associated with each pipe 12a, 12d of the set of pipes and placed near the first end of said pipe.

[0012] The tank 10 further comprises a control system 24. The control system 24 is connected at the input to the various level sensors 14a, 14d. The tank 10 also comprises a valve associated with each pipe, this valve being controlled by the control system 24 in such a way that when the fuel level sensor 14a, 14d associated with this pipe detects a low fuel level, the valve is controlled in the closed position and otherwise the valve is controlled in the open position. According to a first alternative, the various valves are integrated into the manifold 16, as in the embodiment shown in the figure 2 . They are not shown in the figure so as not to overload it. Alternatively, the valves are mounted in series on the pipes to which they are associated.

[0013] In operation, when the aircraft is in a substantially horizontal position, whether in flight or on the ground, the lower wall 22 and the lower part 28 of the tank are horizontal or substantially horizontal. Consequently, as long as there is sufficient fuel remaining in the tank, the first ends of the various pipes 12a, 12d of the set of pipes are covered with fuel and none of the level sensors 14a, 14d detects a low fuel level. Consequently, the control system 24 controls the various valves associated with these pipes in the open position, such that when the pump 18 is in operation, fuel is drawn into the tank by each of said pipes. The fuel arrives at the pump 18 via the pipes 12a, 12d and the manifold 16. At the outlet of the pump, the fuel is transmitted to the user system via a pipe 26.

[0014] When the tank 10 is tilted due to an inclination of the aircraft in certain flight phases of the aircraft, the first end of at least one of the pipes is no longer covered with fuel. The level sensor associated with this pipe then detects a low fuel level. Consequently, the control system 24 controls the closing of the valve associated with this pipe. Consequently, when the pump 18 is in operation, there is no risk of air being sucked in through the first end of said pipe. This ensures the proper operation of the pump and the user system since the pump 18 does not risk sucking in air. Furthermore, given that the tank is tilted and the first ends of the different pipes 12a, 12d are distributed over the lower part 28 of the tank, the first end of at least one of the pipes of the set of pipes is covered with fuel.Therefore, as already explained when the tank 10 is in a horizontal position, the valve associated with this pipe is controlled in the open position by the control system 24 and the pump 18 draws fuel into the tank through said pipe. This makes it possible to guarantee the continuity of fuel supply to the user system.

[0015] In a particular embodiment, as illustrated in the figure 2 , the shell 20 of the tank is of elongated shape along a length of said tank, in particular of cylindrical shape, closed at its ends by two domes. The set of pipes comprises for example four pipes 12a, 12b, 12c, 12d. The first end of a first pipe 12a is located near a first end of said length. The first end of a second pipe 12d is located near a second end of the length, opposite the first end of said length. The first ends of two other pipes 12b and 12c are located on either side of the middle of the length of the tank, between the first ends of the first pipe 12a and the second pipe 12d.The first ends of the different pipes of the set of pipes are thus distributed over the lower part 28 of the tank according to its length, which makes it possible to ensure that the first end of at least one of said pipes is always covered with fuel when the tank 10 is inclined and that there remains sufficient fuel in the tank. In particular, the first ends of the other two pipes 12b and 12c are furthermore located on either side of a longitudinal axis of the tank (i.e. on either side of the plane of the figure). This makes it possible to ensure that the first end of at least one of the other two pipes 12b, 12c is always covered with fuel when the tank 10 is inclined laterally (for example due to a rolling movement of the aircraft) and that there remains sufficient fuel in the tank.

[0016] In the embodiment illustrated in the figure 3 , the lower part 28 of the tank is shaped so as to have a low point 36 at the location of the first end 13 of at least one of the pipes 12 of the set of pipes 12a ... 12d. In particular, the low point 36 corresponds to a downwardly oriented boss, made in the lower wall 22 of the tank 10. Preferably, the low point is shaped to receive the first end 13 of the pipe 12, as well as at least a lower part of the level sensor 14 associated with this pipe. Having such a low point 36 at the location of the first end of the pipe 12 makes it easier for the fuel to converge towards said first end of the pipe, even when there is little fuel left in the tank.

[0017] In one embodiment illustrated in the figure 4 , the tank comprises a partition 30 partially covering the lower part 28 of the tank and spaced from the lower wall 22 of the tank in such a way that the first ends of the pipes as well as the level sensors are located between the lower wall 22 of the tank and said partition 30. The partition 30 has the effect of preventing the fuel contained under this partition from moving suddenly upwards during a rapid reduction in the force of gravity which may occur during the flight of the aircraft, or even when the fuel is subjected to an upwardly oriented acceleration force. Thanks to this partition 30, the fuel is then maintained in the lower part 28 of the tank in such a way that the first end of at least one of the pipes remains covered by the fuel. This makes it possible to guarantee the continuity of the pumping of fuel by the pump 18 and therefore the supply of fuel to the user system.The partition 30 only partially covers the lower part 28 of the tank, so as to allow said lower part to be filled with fuel. In particular, the partition 30 is not contiguous with the shell 20 of the tank so that the fuel can flow between this shell 20 and an edge of the partition 30 to fill the lower part 28 of the tank. Preferably, the partition 30 is equipped with at least one valve 32 provided to allow the evacuation to an upper part of the tank of gas contained between the lower wall 22 of the tank and said partition 30. This makes it possible to avoid the accumulation of gas in the lower part 28 of the tank, under the partition 30, in particular due to evaporation of part of the fuel.This further helps to ensure that the first end of at least one of the pipes remains covered by the fuel and therefore to ensure the continuity of the pumping of fuel by the pump 18 and therefore the supply of fuel to the user system. In a particular embodiment, the tank comprises a set of walls 34 each extending between the partition 30 and the lower wall 22 of the tank. These walls 34 make it possible to avoid sudden movements of the fuel in the lower part 28 of the tank during movements of the aircraft. They therefore help to prevent the first ends of certain pipes from no longer being covered with fuel in such a situation. In particular, the walls of the set of walls 34 delimit sub-volumes of the tank between the partition 30 and the lower wall 22 of the tank, the number of sub-volumes being equal to the number of pipes in the set of pipes as illustrated in the . figure 4 . Advantageously, the walls 34 do not delimit these sub-volumes in a sealed manner, such that the fuel can be distributed between these sub-volumes, but without sudden movements. For this, certain walls comprise, for example, orifices allowing the circulation of the fuel, or the tank comprises walls 34 offset so as to allow the distribution of the fuel between the sub-volumes while limiting sudden movements of the fuel along the length of the tank.

[0018] In a non-limiting manner of the invention, the fuel tank 10 is for example integrated into a nacelle of a propulsion engine 3 of the aircraft 1 as shown in the figure 1. This engine is then either a combustion engine using fuel as an energy source, or an electric motor powered electrically by fuel cells using fuel, in particular hydrogen, as an energy source. In another exemplary embodiment, the fuel tank 10 is integrated into a fuselage 2 of the aircraft, in particular in a rear part of the fuselage.

Claims

1. Fuel tank (10) for an aircraft (1), comprising a fuel pumping system in said tank, the fuel pumping system comprising: - a set of hoses (12a ... 12d) comprising at least two hoses, a first end of each hose being disposed in a lower part (28) of the tank, the first ends of the different hoses of the set of hoses being distributed over the lower part (28) of the tank; - a fuel pump (18); and - a manifold (16) to which second ends of the different hoses (12a ... 12d) of the set of hoses are connected as input, an outlet of the manifold being connected to the fuel pump, the fuel pumping system further comprising: - a set of fuel level sensors (14a ... 14d) such that a fuel level sensor is associated with each hose of the set of hoses and is placed in the vicinity of the first end of said hose; and - a valve associated with each hose, this valve being controlled by a control system (24) in such a way that when the fuel level sensor associated with this hose detects a low fuel level, the valve is controlled into a closed position, and otherwise the valve is controlled into an open position, the tank additionally comprising a partition (30) which partially covers the lower part (28) of the tank and which is spaced apart from a lower wall (22) of the tank in such a way that the first ends of the hoses and the level sensors are situated between the lower wall (22) of the tank and said partition (30), the partition being equipped with a valve (32) provided to allow gas contained between the lower wall (22) of the tank and said partition (30) to be discharged to an upper part of the tank.

2. Tank according to Claim 1, characterized in that it is of elongate form along a length of said tank and the set of hoses comprises at least four hoses including a first hose (12a) whose first end is situated in the vicinity of a first end of said length, a second hose (12d) whose first end is situated in the vicinity of a second end of the length, opposite the first end of said length, and two other hoses (12b, 12c) whose first ends are situated on either side of the middle of the length of the tank.

3. Tank according to the preceding claim, characterized in that the first ends of the two other hoses (12b, 12c) are also situated on either side of a longitudinal axis of the tank.

4. Tank according to any one of the preceding claims, characterized in that the lower part (28) of the tank is shaped so as to have a low point (36) at the location of the first end (13) of at least one of the hoses (12) of the set of hoses.

5. Tank according to any one of the preceding claims, characterized in that the tank comprises a set of walls (34) each extending between the partition (30) and the lower tank wall (22).

6. Tank according to the preceding claim, characterized in that the walls (34) of the set of walls delimit sub-volumes of the tank between the partition (30) and the lower wall (22) of the tank, the number of sub-volumes being equal to the number of hoses of the set of hoses.

7. Aircraft (1), characterized in that it comprises a tank (10) according to any one of the preceding claims.