Venting system for aircraft fuel tanks

Abstract

A ventilation duct (100) extends from the left vent tank (10), crosses the longitudinal plane of symmetry of the aircraft, traverses the wing, passes through the center wing tank (20), and extends to the right vent tank (30), and is fluidly connected to the left vent tank (10) and the right vent tank (30) at both ends; and a ventilation branch branch branches from the ventilation duct (100) to the interior of the center wing tank (20) and is fluidly connected to the interior of the center wing tank (20) through an end opening, wherein the cross-sectional area of ​​the ventilation duct (100) is larger than the cross-sectional area of ​​the ventilation branch branch. The aircraft fuel tank venting system of the present invention has crosswind protection, which enhances the airworthiness of the aircraft.

Description

Technical Field

[0001] This invention belongs to the field of aircraft fuel tank system design, and specifically relates to a venting system for aircraft fuel tanks. Background Technology

[0002] An aircraft's fuel tanks are usually located inside the wings.

[0003] Aircraft fuel tanks are typically connected to external gases to accommodate pressure changes caused by altitude during flight, in order to maintain pressure balance or a specific pressure difference between the aircraft fuel tank and the external environment when external pressure changes.

[0004] A common venting system used to connect aircraft fuel tanks to the outside is typically implemented through a venting tank located near the wingtip.

[0005] It is also common during aircraft operation that the pressure at the outlet of the ventilation system on one side of the aircraft differs from that on the other side. This can lead to a large amount of gas flowing through the ventilation system, also known as crosswinds. It is generally believed that these crosswinds can have undesirable effects on the oxygen concentration in the center wing fuel tank. The center wing fuel tank is located within the fuselage, has poor heat dissipation, and is highly susceptible to explosion. To meet the explosion-proof requirements of the center wing fuel tank, most mainstream commercial airliners install inerting systems that continuously inject inert gas into the fuel tank to reduce the oxygen concentration and prevent explosions. If crosswinds from the ventilation system flow through the vapor space of the center wing fuel tank, the oxygen concentration inside the tank will be increased, potentially negating the inerting effect and producing undesirable consequences. Therefore, it is necessary to suppress these crosswinds.

[0006] Furthermore, the outlet of the venting system's venting line inside the fuel tank may be flooded with fuel due to different flight attitudes of the aircraft (such as roll and / or pitch attitudes, etc.), meaning the vent is submerged. Considering the effect of the inerting system continuously injecting pressurized gas, if the fuel tank venting is obstructed and the fuel tank is pressurized, fuel will continuously flow into the venting system, causing a continuous fuel spill in the venting system. Therefore, it is necessary to take measures to prevent such fuel spills and ensure unobstructed ventilation.

[0007] US8777165B2 discloses a venting system for the A350 aircraft. The design of this venting system prioritizes the uniformity of inert gas distribution within the center wing fuel tank during descent. By using a combination of venting pipes of varying sizes, a mixing zone of fresh air and inert gas is created at the right-hand end compartment of the center wing during descent, thus reducing localized areas of high oxygen levels within the center wing fuel tank. The document also utilizes float valves and piping arrangements to ensure compatibility with the inerting system while preventing fuel spillage.

[0008] US8753429B2 discloses a fuel tank venting system architecture with dehumidification function, in which the venting system design has been used in the A320 aircraft. This configuration focuses on the venting and dehumidification function, reducing the amount of condensate entering the fuel tank during descent by installing a drying medium in the pipeline. This document does not cover features designed to prevent fuel spillage.

[0009] CN103167966B discloses a symmetrically arranged central fuel tank venting system. The venting pipes of the central fuel tank connect to the left and right wing venting tanks in a π-shape, which helps maintain a relatively uniform pressure at the outlets of all venting pipes in the central fuel tank, preventing crosswinds within the tank and facilitating better inerting of the central fuel tank in conjunction with the inerting system. However, this document does not address spill prevention design features, and especially under lateral overload conditions, this design cannot eliminate the risk of spillage from the central wing fuel tank.

[0010] US7621483B2 discloses a design for a fuel tank venting system. This design eliminates the wingtip venting compartments and instead incorporates a venting compartment within the central fuel tank, with each fuel tank connected to this compartment by a piping line. This reduces the difficulty of installing piping in the venting system. This document primarily addresses the engineering challenges of limited space and difficult piping layout in venting systems and does not cover spill prevention design features.

[0011] US8936218B2 discloses a fuel tank venting system design. It eliminates the wingtip venting compartment and instead places two venting chambers on the left and right sides of the bottom of the central fuel tank. Ventilation pipes are installed above and below the outer wing fuel tank, respectively, connecting to these venting chambers. The lower venting pipe is open to the atmosphere. This design represents a novel fuel tank layout and venting system design, effectively solving the problem of difficult wingtip venting fuel tank piping arrangement.

[0012] Aircraft such as the B787 use a cross-venting system. A vent is located on the left side of the center fuel tank, connecting to the right wing vent tank, while a vent is located on the right side, connecting to the left wing vent tank. The two vent lines are not directly connected but are arranged in a cross configuration within the center fuel tank. This arrangement of the center wing fuel tank venting system prevents fuel spillage under lateral loads. Furthermore, by installing a one-way valve on the right-side vent line, the center wing intake process is unilateral, preventing crosswinds from being generated within the center wing fuel tank during intake, which could dilute the inert gas concentration and disrupt the inerting process. By directly injecting inert gas into the right-side vent line, even if the center wing vents are completely submerged in fuel, fuel spillage and overpressure in the center wing fuel tank can be avoided; in other words, this venting system is compatible with inerting systems. Summary of the Invention

[0013] Based on the shortcomings of current technical solutions, this invention mainly targets aircraft with a three-tank layout and proposes a design scheme for a center wing fuel tank ventilation system with crosswind protection to enhance the airworthiness of the aircraft.

[0014] Therefore, the present invention provides a venting system for an aircraft fuel tank, comprising:

[0015] A ventilation duct, which originates from the left vent tank, crosses the longitudinal plane of symmetry of the aircraft, traverses the wing, extends through the center wing tank to the right vent tank, and is in fluid communication with the left and right vent tanks at both ends; and

[0016] A ventilation branch branch, which branches off from the main ventilation duct and leads to the interior of the central wing fuel tank, and is in fluid communication with the interior of the central wing fuel tank through an end opening.

[0017] The cross-sectional area of ​​the main ventilation duct is larger than that of the branch ventilation duct.

[0018] According to a preferred embodiment of the ventilation system of the present invention, the ventilation branch includes:

[0019] A left vent branch, which branches off from the left bifurcation point on the left side of the longitudinal symmetry plane of the vent duct, enters the center wing fuel tank, and extends into the center wing fuel tank near the right vent tank, such that when the aircraft is at its left roll limit position, the end opening of the left vent branch is higher than the fuel level inside the center wing fuel tank; and

[0020] The right vent branch branches off from the right bifurcation point on the right side of the longitudinal symmetry plane of the vent duct and enters the center wing fuel tank, extending into the interior of the center wing fuel tank near the left vent fuel tank, such that when the aircraft is at its right roll limit position, the end opening of the right vent branch is higher than the liquid level inside the center wing fuel tank.

[0021] According to a preferred embodiment of the ventilation system of the present invention, the left bifurcation point is located inside the central wing fuel tank near the left ventilation fuel tank, and the right bifurcation point is located inside the central wing fuel tank near the right ventilation fuel tank.

[0022] According to a preferred embodiment of the ventilation system of the present invention, the ventilation duct is arranged along the rear spars of the wing;

[0023] The left ventilation branch extends from the left bifurcation point towards the front spars of the wing, and then runs along the front spars of the wing; and

[0024] The right ventilation branch extends from the right bifurcation point toward the front spar of the wing and then runs along the front spar of the wing.

[0025] According to a preferred embodiment of the ventilation system of the present invention, the left ventilation branch and the right ventilation branch overlap in the longitudinal direction of the aircraft.

[0026] According to a preferred embodiment of the ventilation system of the present invention, the left ventilation branch extends along the bottom of the central wing fuel tank after leaving the left bifurcation point, and extends towards the top of the central wing fuel tank near its end, opening upwards inside the central wing fuel tank.

[0027] The right vent branch extends along the bottom of the central wing tank after leaving the right bifurcation point, and near its end extends toward the top of the central wing tank, opening upwards inside the central wing tank.

[0028] According to a preferred embodiment of the ventilation system of the present invention, the ventilation duct is arranged such that, when the aircraft is at its maximum pitch angle, the fuel level in the center wing fuel tank is higher at both the left and right bifurcation points.

[0029] According to a preferred embodiment of the ventilation system of the present invention, the ventilation duct is arranged such that it is higher than the fuel level in the center wing fuel tank when the aircraft is in maximum pitch attitude.

[0030] According to a preferred embodiment of the ventilation system of the present invention, a pitch ventilation branch extending toward the top of the central wing fuel tank is provided in the ventilation duct inside the central wing fuel tank. The pitch ventilation branch opens at the top inside the central wing fuel tank to communicate with the fluid inside the central wing fuel tank, and a float valve is provided at the opening. The float valve is configured to close the opening when the liquid level in the central wing fuel tank reaches or exceeds the opening of the pitch ventilation branch, and to keep the opening open in other cases.

[0031] According to a preferred embodiment of the ventilation system of the present invention, the pitch ventilation branch and the corresponding ventilation branch are connected to the ventilation main via a tee joint.

[0032] In summary, according to the preferred embodiment of the present invention, the center wing fuel tank can be effectively connected to the outside atmosphere under various flight attitudes, preventing the vent / pipe from being submerged in fuel, avoiding poor fuel tank exhaust, and at the same time reducing the impact of crosswinds on the performance of the center wing inerting system. Attached Figure Description

[0033] This document includes accompanying drawings to provide a further understanding of various embodiments. The drawings are incorporated in and form part of this specification.

[0034] The accompanying drawings illustrate various embodiments described herein and, together with the textual description, serve to explain the principles and operation of the claimed subject matter.

[0035] With reference to the above objectives, the technical features of the present invention are clearly described below, and its advantages will be apparent from the following detailed description with reference to the accompanying drawings, which illustrate preferred embodiments of the invention by way of example, without limiting the scope of the invention.

[0036] In the attached image:

[0037] Figure 1 A top view of the plan arrangement of an aircraft fuel tank venting system according to a preferred embodiment of the present invention is shown.

[0038] Figure 2 It shows Figure 1 A side sectional view of a preferred embodiment of the aircraft fuel tank venting system, wherein the aircraft is in a pitch-up climbing attitude.

[0039] Figure 3 It shows Figure 1 A side sectional view of a preferred embodiment of an aircraft fuel tank venting system, wherein the aircraft is in a cruise attitude.

[0040] Figure 4 It shows Figure 1 A side sectional view of a preferred embodiment of an aircraft fuel tank venting system, wherein the aircraft is in a nose-down descent attitude.

[0041] List of reference numerals

[0042] 10. Left-side vent fuel tank

[0043] 20 Central Wing Fuel Tanks

[0044] 21. Bottom of the central wing fuel tank

[0045] 22. Top of the center wing fuel tank

[0046] 30 Right-side vent fuel tank

[0047] 100 ventilation ducts

[0048] 110 Pitch ventilation branch

[0049] 111 Float Valve

[0050] 210 Left ventilation branch

[0051] 211 left bifurcation point

[0052] 212 The terminal opening of the left ventilation branch

[0053] 220 Right ventilation branch

[0054] 221 right bifurcation point

[0055] 222 The end opening of the right ventilation branch Detailed Implementation

[0056] Embodiments of the invention will now be described in detail, examples of which are shown in the accompanying drawings and described below.

[0057] Although the invention will be described in conjunction with exemplary embodiments, it should be understood that this specification is not intended to limit the invention to the embodiments illustrated. Rather, the invention is intended to cover not only these exemplary embodiments, but also various alternatives, modifications, equivalents, and other embodiments that may be included within the spirit and scope of the invention.

[0058] To facilitate explanation and precise definition of the technical solutions of the present invention, the terms "upper," "lower," "inner," and "outer" are used to describe these features with reference to the positions of features in the exemplary embodiments shown in the accompanying drawings.

[0059] Various preferred, but non-limiting, embodiments of the aircraft fuel tank venting system of the present invention will be described in detail below with reference to the accompanying drawings.

[0060] First refer to Figure 1 This paper illustrates a preferred embodiment of a venting system for an aircraft fuel tank. The venting system includes a main vent 100 and venting branches.

[0061] Ventilation duct 100 extends from the left vent tank 10, crosses the longitudinal plane of symmetry of the aircraft, traverses the wing, passes through the center wing tank 20, and reaches the right vent tank 30, and is fluidly connected to the left vent tank 10 and the right vent tank 30 at both ends; and

[0062] The ventilation branch branches off from the ventilation duct 100 and leads to the interior of the central wing fuel tank 20, and is in fluid communication with the interior of the central wing fuel tank 20 through the end opening.

[0063] According to the basic concept of the present invention, the cross-sectional area of ​​the ventilation trunk 100 is larger than the cross-sectional area of ​​the ventilation branch.

[0064] Continue to refer to Figure 1 The ventilation duct 100 may be arranged along the rear spar 1 of the wing. However, those skilled in the art will understand that the arrangement of the ventilation duct 100 is not limited to this, but may be arranged close to the front spar at least in the direction relative to the front spar 2 to the rear spar 1.

[0065] like Figure 1As shown in the embodiment, the ventilation branches may preferably include a left ventilation branch 210 and a right ventilation branch 220. However, those skilled in the art will understand that the two ventilation branches do not necessarily need to exist simultaneously to improve the crosswind problem in the prior art, but at least one of them is sufficient to improve the relevant technical problem.

[0066] The left vent branch 210 branches off from the left bifurcation point 211 on the left side of the longitudinal symmetry plane of the vent duct 100 and enters the center wing fuel tank 20, extending into the interior of the center wing fuel tank 20 near the right vent fuel tank 30, so that when the aircraft is in the left roll limit position, the end opening 212 of the left vent branch 210 is higher than the liquid level inside the center wing fuel tank 20.

[0067] Preferably, and with reference Figure 1 It can be seen that the left bifurcation point 211 can be located inside the central wing fuel tank 20 near the left vent fuel tank 10. However, it should be noted that, in general, the arrangement of the left bifurcation point 211 is not limited to this, as long as the left vent branch 210 can extend into the central wing fuel tank 20.

[0068] Furthermore, the left vent branch 210 can extend from the left bifurcation point 211 towards the front spar 2 of the wing, and then be arranged along the front spar 2 of the wing.

[0069] The right vent branch 220 branches off from the right bifurcation point 221 on the right side of the longitudinal symmetry plane of the vent duct 100 and enters the center wing fuel tank 20, extending into the interior of the center wing fuel tank 20 near the left vent fuel tank 10, so that when the aircraft is at the right roll limit position, the end opening 222 of the right vent branch 220 is higher than the liquid level inside the center wing fuel tank 20.

[0070] Preferably, and with reference Figure 1 It can be seen that the right bifurcation point 221 can be located inside the central wing fuel tank 20 near the right vent fuel tank 30. However, it should be noted that, generally, the arrangement of the right bifurcation point 221 is not limited to this, as long as the right vent branch 220 can extend into the central wing fuel tank 20.

[0071] Furthermore, the right ventilation branch 220 can extend from the right bifurcation point 221 toward the front spar 2 of the wing, and then be arranged along the front spar 2 of the wing.

[0072] exist Figure 1 In the preferred embodiment shown, the left vent branch 210 and the right vent branch 220 overlap in the longitudinal direction of the aircraft. That is, at least one of them extends across the longitudinal plane of the aircraft. Figure 1 Both of them extend beyond the longitudinal plane of the aircraft.

[0073] refer to Figures 2 to 4It can be seen that, in the preferred embodiment, the left vent branch 210 extends along the bottom 21 of the central wing fuel tank 20 after leaving the left bifurcation point 211, and extends towards the top 22 of the central wing fuel tank 20 near its end, opening at the upper part of the central wing fuel tank 20.

[0074] Same reference Figures 2 to 4 It can be seen that, in the preferred embodiment, the right vent branch 220 extends along the bottom 21 of the central wing fuel tank 20 after leaving the right bifurcation point 221, and extends toward the top 22 of the central wing fuel tank 20 near its end, opening at the top inside the central wing fuel tank 20.

[0075] In a preferred embodiment of the invention, and see also Figure 4 The ventilation duct 100 can be arranged such that, when the aircraft is in maximum pitch attitude, the fuel level in the center wing fuel tank is higher at both the left bifurcation point 211 and the right bifurcation point 221.

[0076] In a preferred embodiment of the invention, see also Figure 4 The ventilation duct 100 is arranged so that it is higher than the fuel level in the center wing fuel tank when the aircraft is at its maximum pitch angle.

[0077] Continue to refer to Figures 2 to 4 Preferably, a pitch vent branch 110 extending toward the top 22 of the central wing fuel tank 20 may be provided on the vent duct 100 within the central wing fuel tank 20. The pitch vent branch 110 opens slightly above the interior of the central wing fuel tank 20 to allow fluid communication with the interior of the central wing fuel tank 20, and a float valve 111 is provided at the opening. The float valve 111 is configured to close the opening when the liquid level in the central wing fuel tank reaches or exceeds the opening of the pitch vent branch 110, and to keep the opening open under other conditions. See [reference needed]. Figures 2 to 4 The illustration.

[0078] The pitch ventilation branch 110 is connected to the corresponding ventilation branch via a tee joint, also known as a T-joint, to the ventilation main 100.

[0079] The preferred embodiments of the present invention have been described in detail above, but it should be understood that, if necessary, aspects of the embodiments can be modified to utilize aspects, features, and concepts from various patents, applications, and publications to provide other embodiments.

[0080] Given the detailed description above, various readily conceivable variations can be made to the embodiments described herein.

[0081] Generally speaking, the terminology used in the claims should not be considered as limited to the specific embodiments disclosed in the specification and claims, but should be understood to include all possible embodiments together with the full scope of equivalents enjoyed by the claims.

Claims

1. A venting system for aircraft fuel tanks, include: A ventilation duct (100) extends from the left vent tank (10), across the longitudinal plane of symmetry of the aircraft, through the center wing tank (20), to the right vent tank (30), and is in fluid communication with the left vent tank (10) and the right vent tank (30) at both ends; and A ventilation branch, which branches off from the main ventilation duct (100) and leads to the interior of the center wing fuel tank (20) and is in fluid communication with the interior of the center wing fuel tank (20) through an end opening, the ventilation branch including: a left ventilation branch (210), which branches off from the left bifurcation point (211) on the left side of the longitudinal symmetry plane of the main ventilation duct (100) and enters the center wing fuel tank (20), and extends to the interior of the center wing fuel tank (20) near the right ventilation fuel tank (30), so that when the aircraft is in the left roll limit position... The left vent branch (210) has an end opening (212) higher than the liquid level inside the center wing fuel tank (20); and a right vent branch (220) branches off from the right bifurcation point (221) on the right side of the longitudinal symmetry plane of the ventilator (100) into the center wing fuel tank (20), and extends into the center wing fuel tank (20) near the left vent tank (10), such that when the aircraft is at its right roll limit position, the end opening (222) of the right vent branch (220) is higher than the liquid level inside the center wing fuel tank (20). in, The cross-sectional area of ​​the ventilation main (100) is larger than that of the ventilation branch.

2. The ventilation system according to claim 1, Its features are, The left bifurcation point (211) is located inside the central wing fuel tank (20) near the left vent fuel tank (10), and The right bifurcation point (221) is located inside the central wing fuel tank (20) near the right vent fuel tank (30).

3. The ventilation system according to claim 1, Its features are, The ventilation duct (100) is arranged along the rear spars (1) of the wing; The left ventilation branch (210) extends from the left bifurcation point (211) towards the front spar (2) of the wing, and then runs along the front spar (2) of the wing; and The right ventilation branch (220) extends from the right bifurcation point (221) toward the front spar (2) of the wing and then runs along the front spar (2) of the wing.

4. The ventilation system according to claim 3, Its features are, The left ventilation branch (210) and the right ventilation branch (220) overlap in the longitudinal direction of the aircraft.

5. The ventilation system according to claim 3, Its features are, The left vent branch (210) extends along the bottom (21) of the central wing fuel tank (20) after leaving the left bifurcation point (211), and extends towards the top (22) of the central wing fuel tank (20) near its end, opening upwards inside the central wing fuel tank (20). The right vent branch (220) extends along the bottom (21) of the central wing tank (20) after leaving the right bifurcation point (221), and extends toward the top (22) of the central wing tank (20) near its end, opening at the top inside the central wing tank (20).

6. The ventilation system according to claim 5, Its features are, The ventilation duct (100) is arranged such that, when the aircraft is in maximum pitch attitude, the fuel level in the center wing fuel tank is higher at both the left bifurcation point (211) and the right bifurcation point (221).

7. The ventilation system according to claim 6, Its features are, The ventilation duct (100) is arranged such that it is above the fuel level in the center wing fuel tank when the aircraft is in maximum pitch attitude.

8. The ventilation system according to claim 5, Its features are, The ventilation duct (100) is provided with a pitch ventilation branch (110) extending toward the top (22) of the central wing fuel tank (20) inside the central wing fuel tank (20). The pitch ventilation branch (110) opens at the top inside the central wing fuel tank (20) to communicate with the interior of the central wing fuel tank (20) in fluid communication. A float valve (111) is provided at the opening. The float valve (111) is configured to close the opening when the liquid level in the central wing fuel tank reaches or exceeds the opening of the pitch ventilation branch (110) and keep the opening open in other cases.

9. The ventilation system according to claim 8, Its features are, The pitch ventilation branch (110) and the corresponding ventilation branch are connected to the ventilation main (100) via a tee joint.

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