Vent devices for fuel tanks and fuel tanks for aircraft

Abstract

This invention relates to a venting device for a fuel tank, comprising: a venting pipe having a port section extending toward the upper wall of the fuel tank; a floating venting member having a through hole, disposed around the port section and floating along the port section in response to changes in the fuel level in the fuel tank; and a limiting structure disposed at the port section and housed between an upper stop and a lower stop of the floating venting member. When the fuel level in the fuel tank decreases to the lower limit position of the floating venting member, the limiting structure contacts the upper stop; when the fuel level increases to the upper limit position of the floating venting member, the limiting structure contacts the lower stop. This increases the height preventing fuel from overflowing into the venting pipe, prolongs the venting time of the fuel tank, and also preserves the fuel flow capacity of the venting pipe, effectively preventing fuel tank pressure buildup. This invention also provides a fuel tank for an aircraft, which may include the venting device described above.

Description

Technical Field

[0001] This invention relates to the field of civil transport aircraft design, and more specifically to the design of fuel tank venting systems. Background Technology

[0002] Civil aircraft main fuel tanks typically employ an open venting system. This system uses venting lines to connect the empty space above the fuel level in each tank to the outside atmosphere. This ensures that the pressure difference between the inside and outside of the fuel tank remains within acceptable limits during refueling, altitude changes, temperature variations, and aircraft maneuvers, thus protecting the aircraft's fuel tank structure. The venting system lines are usually installed above the fuel tanks, with multiple vents in each tank to ensure that at least one vent is above the fuel level under different aircraft attitudes or scenarios.

[0003] Aircraft fuel tanks typically have two types of vent ports: open vent ports and vent float valves. To prevent fuel tank pressure buildup, each fuel tank is equipped with an open vent port. At the same time, to minimize fuel entering the vent line through the vent port, some vent line outlets are equipped with vent float valves.

[0004] According to existing technology, current civil aircraft main fuel tanks generally adopt an open venting system based on venting lines. In this system, one part of the vent in each fuel tank is equipped with a float valve device, while the other part is an open vent. Currently, there are two main structural types of fuel tank venting devices, as shown in existing technical document CN112407305A and the accompanying drawings in this specification. Figure 1 One type is a vent valve commonly used in the fuel tanks of small aircraft such as helicopters. It automatically aligns and compensates via a limit compensation component, where the valve plate and float are integrated, resulting in a complex structure that is difficult to install and replace. Another type is a vent float valve device, as seen in prior art documents US8596289B2 and EP3590825A1 and the accompanying drawings in this specification. Figure 2-3 Large passenger aircraft typically use these venting float valve structures for their fuel tank venting systems. Both of these structures achieve vent closure through a floating mechanism. For open vents, the current systems use simple fixed pipe outlets.

[0005] Due to lightning protection requirements for aircraft fuel tanks, the distance between the open vent and the upper wall of the fuel tank must be at least 0.5 inches. When the fuel level in the tank is high and the aircraft is maneuvering, fuel in the tank can easily flow into the vent line through the open vent and then leak outside the aircraft, creating a fire hazard.

[0006] In view of the requirements for ventilation performance and reduction of fuel spillage in the above-mentioned prior art, it is necessary to provide a vent device that can improve the above-mentioned shortcomings. Summary of the Invention

[0007] The present invention was made in view of the above-mentioned technical problems, and its object is to provide a vent device for a fuel tank, which can improve the performance of the venting system and minimize the amount of fuel entering the venting line from the vent.

[0008] To solve the above-mentioned technical problems, the present invention provides a vent device for an oil tank, the vent device comprising:

[0009] A venting line, the venting line including a port section extending toward the upper wall of the fuel tank, the port section having a first inner diameter;

[0010] A floating vent member is provided with an axially extending through hole and is arranged around the pipe opening section such that the pipe opening section is located within the through hole, and the floating vent member is configured to float along the pipe opening section as the fuel level in the fuel tank changes.

[0011] A limiting structure is provided at the pipe opening section and is configured to restrict the floating ventilator between its upper and lower limit positions when the floating ventilator is floating.

[0012] According to the above technical solution, the vent device of the present invention can achieve the following beneficial technical effects: the vent device of the present invention has a simple structure, can be easily installed at the pipe opening section of an open venting pipeline, and floats with the rise / fall of the fuel level in the fuel tank, which can effectively reduce the amount of fuel entering the venting pipeline, while not affecting the venting efficiency of the venting pipeline.

[0013] According to a preferred embodiment of the vent device for a fuel tank of the present invention, the floating vent member may have an upper stop portion protruding inward toward the venting line and a lower stop portion below the upper stop portion, wherein, at the upper limit position, the limiting structure contacts the lower stop portion, and at the lower limit position, the limiting structure contacts the upper stop portion.

[0014] According to the above technical solution, the vent device of the present invention can achieve the following beneficial technical effects: the setting of the upper stop and the lower stop in the vent device of the present invention can more accurately limit the floating range of the vent device, so as to maximize the ventilation performance of the vent device.

[0015] According to a preferred embodiment of the vent device for an oil tank of the present invention, the inner diameter of the portion of the through hole between the upper stop and the lower stop can be larger than the inner diameter of the upper opening and the inner diameter of the lower opening of the through hole, so as to more stably accommodate the limiting structure.

[0016] According to a preferred embodiment of the vent device for a fuel tank of the present invention, the limiting structure may be configured as an annular flange surrounding the port section of the vent pipe.

[0017] According to the above technical solution, the vent device of the present invention can achieve the following beneficial technical effects: the limiting structure constructed as an annular flange can prevent tilting or oil leakage caused by unstable contact when in contact with the upper stop and lower stop of the floating vent component, thereby improving the stability of their contact and the sealing effect.

[0018] According to a preferred embodiment of the vent device for a fuel tank of the present invention, when the fuel level in the fuel tank drops to the lower limit position of the floating vent member, the upper surface of the annular flange engages with the lower surface of the upper stop portion; when the fuel level in the fuel tank rises to the upper limit position of the floating vent member, the lower surface of the annular flange engages with the upper surface of the lower stop portion.

[0019] According to the above technical solution, the vent device of the present invention can achieve the following beneficial technical effects: the surface contact between the upper stop and lower stop of the floating vent component and the limiting structure helps to improve the stability of the contact and the sealing effect.

[0020] According to a preferred embodiment of the vent device for a fuel tank of the present invention, the lower surface of the limiting structure and the upper surface of the lower stop can be inclined accordingly. When the fuel level in the fuel tank rises to the point that the floating vent member reaches the upper limit position, the lower surface of the limiting structure engages with the inclined surface of the upper surface of the lower stop to ensure a tight seal when they are joined.

[0021] According to the above technical solution, the vent device of the present invention can achieve the following beneficial technical effects: the structure helps to ensure that the lower surface of the limiting structure is in close contact with the upper surface of the lower stop when the oil level in the oil tank rises to the upper limit position of the floating vent member, preventing oil from entering the through hole from the lower opening of the through hole of the floating vent member and filling the vent pipe, so as to achieve a better sealing effect.

[0022] According to a preferred embodiment of the vent device for a fuel tank of the present invention, the vent device can be designed such that...

[0023] When the floating ventilated component is in its lower limit position, the distance between the upper opening of the through hole and the upper wall plate satisfies: H*D≥d 2 / 4, where H is the distance between the upper opening of the through hole and the upper wall plate, D is the inner diameter of the upper opening of the through hole, and d is the first inner diameter;

[0024] When the floating ventilation component is in its upper limit position, the distance between the upper opening of the through hole and the upper wall plate satisfies: H*D≥d 2 / 5, where H is the distance between the upper opening of the through hole and the upper wall plate, D is the inner diameter of the upper opening of the through hole, and d is the first inner diameter.

[0025] According to the above technical solution, the vent device of the present invention can achieve the following beneficial technical effects: ensuring that the vent device has full venting capacity when the oil level is low, and still ensuring a certain venting capacity when the oil level is high for a short time, so as to avoid causing the oil tank to become pressurized.

[0026] According to a preferred embodiment of the vent device for a fuel tank of the present invention, the limiting structure may be integrally disposed at or fixedly connected to the vent section of the vent pipe.

[0027] According to a preferred embodiment of the vent device for a fuel tank of the present invention, the floating vent member includes a housing, which may be solid or hollow.

[0028] According to a preferred embodiment of the vent device for an oil tank of the present invention, the outer surface of the top of the housing of the floating vent member may be inclined to facilitate the flow of oil in the oil tank along the outer surface.

[0029] According to the above technical solution, the vent device of the present invention can achieve the following beneficial technical effects: it can effectively reduce the risk of oil entering the venting pipeline from the upper orifice of the through hole of the floating venting component.

[0030] The present invention also provides a fuel tank for an aircraft, the fuel tank including the vent device described above.

[0031] In summary, compared with the prior art, the beneficial effects of the present invention are:

[0032] The floating venting component that can move with the fuel level is equivalent to extending the venting pipe section toward the upper wall of the fuel tank, increasing the height to prevent fuel from overflowing into the venting pipe and extending the fuel tank venting time.

[0033] Furthermore, the design principle of the distance between the floating venting component and the upper wall of the fuel tank ensures the venting performance of the fuel tank, while also preserving the fuel flow capacity of the venting pipeline to meet certain flow requirements, which can effectively prevent fuel tank pressure buildup.

[0034] Additional features and advantages of the vent device for fuel tanks described herein will be set forth in the detailed description below, and will be recognized by those skilled in the art either by the following description or by practice of the embodiments described herein, including the detailed description below, the claims, and the drawings.

[0035] It should be understood that the foregoing general description and the following detailed description illustrate various embodiments and are intended to provide an overview or framework for understanding the nature and characteristics of the claimed subject matter. The accompanying drawings illustrate the various embodiments described herein and, together with the description, are used to explain the principles and operation of the claimed subject matter. Attached Figure Description

[0036] With reference to the above objectives, the technical features of the present invention are clearly described in the following claims, 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 inventive concept.

[0037] Figure 1 This is a schematic diagram of the structure of a vent valve for a helicopter fuel system in the prior art;

[0038] Figure 2 This is a schematic diagram of the structure of the venting float valve in the fuel tank venting system of a large passenger aircraft, based on existing technology.

[0039] Figure 3 This is a schematic diagram of another venting float valve in the fuel tank venting system of a large passenger aircraft, which is a prior art technology.

[0040] Figure 4 This is a schematic diagram of the floating vent member in the vent device for an oil tank according to the present invention when the oil level is low.

[0041] Figure 5 This is a schematic diagram of the floating vent member in the vent device for an oil tank according to the present invention when the oil level is high.

[0042] Figure 6 This is a partially enlarged schematic diagram of the floating vent member in the vent device for an oil tank according to the present invention when the oil level is high.

[0043] Figure 7 This is a schematic diagram of the ventilation area above the vent device for an oil tank according to the present invention.

[0044] List of reference numerals

[0045] 1. Ventilation piping;

[0046] 2. Pipe section;

[0047] 3. Floating ventilation components;

[0048] 4. Limiting structure;

[0049] 5. Upper stop section;

[0050] 6. Lower stop section;

[0051] 10. Upper wall panel;

[0052] A. Fuel level;

[0053] D (inner diameter of the upper opening of the through hole);

[0054] d First inner diameter;

[0055] The distance between the upper opening of the H-through hole and the upper wall plate;

[0056] The ventilation area above the S1 vent device;

[0057] The ventilation area of ​​the pipe opening section of the S2 ventilation pipeline. Detailed Implementation

[0058] Reference will now be made in detail to various embodiments of the invention, examples of which are shown in the accompanying drawings and described below.

[0059] 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 those exemplary embodiments. 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 as defined by the appended claims.

[0060] For ease of interpretation and precise definition in the appended claims, the terms “upper,” “lower,” “inner,” and “outer” are used to describe features with reference to their location in the exemplary embodiments shown in the figures.

[0061] Civil aircraft main fuel tanks typically have one or more open vent lines, installed independently of the vent line housing the float valve. These are usually simply installed inside the fuel tank to balance the gas pressure inside and outside the tank. For example, when the fuel level in the tank rises to a certain height to close the float valve, the open vent line prevents tank pressure buildup and allows excess fuel to overflow. The open vent line usually has at least one bend, with one end connected to the outside of the fuel tank and the other end located inside the tank with a nozzle extending above the fuel level to connect the fuel-free space above the fuel level to the outside atmosphere. However, due to lightning protection requirements for aircraft fuel tanks, the distance between the nozzle of the open vent line and the upper wall of the fuel tank should be at least 0.5 inches. Therefore, existing open vent lines require extended venting time and minimal fuel overflow. The vent device according to the present invention includes a vent line 1, which is an open vent line. The vent pipe 1 includes a port section 2 extending toward the upper wall of the fuel tank. This port section 2 is typically an axially extending hollow cylinder with a first inner diameter d. Here, the term "axial" refers to the direction of extension substantially toward the upper wall of the fuel tank, and does not require a completely straight extension.

[0062] The venting device according to the present invention further includes a floating venting member 3. The floating venting member 3 has a through hole extending axially along the pipe section 2 and is arranged around the pipe section 2 through the through hole, such that the pipe section is located within the through hole. This allows the floating venting member 3 to float along the pipe section 2 as the fuel level A in the fuel tank changes, without affecting the ventilation performance of the venting line and allowing excessive fuel overflow. The through hole has an upper orifice inner diameter D and a lower orifice inner diameter. The size of the upper orifice inner diameter D affects the ventilation area S above the venting device. The lower orifice inner diameter should be designed to allow the floating venting member 3 to float smoothly along the pipe section 2 without allowing excessive fuel to enter from the bottom of the floating venting member 3. Furthermore, the overall height of the housing of the floating venting member 3 is between the distance between the venting line 1 and the upper wall plate 10 when the venting device is not installed, to extend the ventilation time while preventing the venting device from colliding with the upper wall plate 10 of the fuel tank and causing damage. Furthermore, the floating ventilation component 3 in the ventilation port device can be installed integrally or in stages onto the port section 2 of the ventilation pipeline 1.

[0063] The vent device also includes a limiting structure 4 disposed at the port section 2, protruding radially outward from the port section (e.g., its outer surface) to limit the floating range of the floating vent member 3, confining it between an upper limit position and a lower limit position. In some embodiments, the vent device may also include a separate stop that works in conjunction with the limiting structure, such as a rod or plate laterally inserted into the port section 2 or into a through hole of the floating vent member 3, to prevent the floating vent member 3 from detaching from the port section 2 during floating.

[0064] like Figure 4 As shown, in a preferred embodiment, the through-hole of the floating vent member 3 preferably has an upper stop 5 protruding inward toward the pipe section 2 and a lower stop 6 below the upper stop. The inner diameter of the portion of the through-hole between the upper stop 5 and the lower stop 6 is larger than the inner diameter D of the upper orifice and the inner diameter of the lower orifice of the through-hole to accommodate the limiting structure 4. The limiting structure 4 restricts the floating vent member 3 to the upper limit position and the lower limit position by contacting the upper stop 5 and the lower stop 6. The positions of the upper stop 5 and the lower stop 6 on the through-hole can be adjusted according to the initial distance between the pipe section 2 of the open vent pipe and the upper wall plate 10 of the oil tank and the oil storage level of the oil tank. They can be located at the two ends of the through-hole or at a certain distance from the ends to maximize the ventilation performance of the vent device.

[0065] The limiting structure 4 can preferably be configured as an annular flange surrounding the pipe opening section 2 of the vent pipe 1. More preferably, the limiting structure 4 can be integrally disposed at or fixedly connected to the pipe opening section 2. When the fuel level A in the fuel tank drops to the lower limit position of the floating vent member 3, the upper surface of the limiting structure 4 can engage with the lower surface of the upper stop part 5. When the fuel level A in the fuel tank rises to the upper limit position of the floating vent member 3, the lower surface of the limiting structure 4 can engage with the upper surface of the lower stop part 6. This ensures that the upper and lower surfaces of the limiting structure 4 are in contact with the upper and lower stops of the floating vent member 3 even when the fuel in the fuel tank sloshes or the floating vent member 3 rotates, preventing tilting or oil leakage caused by uneven contact and improving the sealing effect when they are in contact.

[0066] Additionally, in a preferred embodiment, the housing of the floating vent member 3 can be solid or hollow. The floating vent member is preferably made of an insulating material with a density less than that of fuel, such as rubber and plastic, or preferably made of other insulating materials with a hollow housing, to ensure that the floating vent member 3 can float in the fuel. Furthermore, the top outer surface of the housing of the floating vent member 3 is preferably inclined to facilitate fuel flow down the top outer surface of the housing.

[0067] Figure 4 and Figure 5 The diagrams show the floating vent component 3 in the vent device when it is at a low oil level and a high oil level, respectively.

[0068] like Figure 4 As shown, in a preferred embodiment, when the fuel level A is not higher than the upper surface of the limiting structure 4 installed on the pipe section 2 of the vent pipe 1, the floating vent member 3 is in the lower limit position, and the upper surface of the limiting structure 4 is engaged with the lower surface of the upper stop portion 5 of the floating vent member 3.

[0069] like Figure 5 As shown, in a preferred embodiment, when the fuel level A is higher than the upper surface of the limiting structure 4 installed on the pipe section 2 of the vent pipe 1, the floating vent member 3 floats up with the fuel level A until the lower surface of the limiting structure 4 engages with the upper surface of the lower stop portion 6 of the floating vent member 3. At this time, the floating vent member is in the upper limit position.

[0070] like Figure 6 As shown, in a further preferred embodiment, the lower surface of the limiting structure 4 and the upper surface of the lower stop 6 of the floating vent member 3 can be configured to be inclined accordingly. When the floating vent member 3 reaches its upper limit position, the lower surface of the limiting structure 4 and the upper surface of the lower stop 6 can be inclined to improve the sealing performance when they are joined, and prevent oil from entering the through hole from the lower opening of the through hole of the floating vent member 3 and filling the vent pipe 1.

[0071] Considering that the difference between the ventilation area S1 above the vent device and the ventilation area S2 of the pipe opening section of the ventilation pipeline when the vent device is not installed will affect the ventilation performance of the ventilation pipeline, the present invention also proposes a design method for the above-mentioned vent device.

[0072] Figure 7 A schematic diagram of the ventilation area above the vent device for an oil tank according to the present invention is shown. The ventilation area S1 above the vent device is the lateral area of ​​the cylinder formed between the upper opening of the through hole of the floating vent member 3 and the upper wall plate 10 of the oil tank, i.e., S1 = π * D * H (where D is the inner diameter of the upper opening of the through hole, and H is the distance between the upper opening of the through hole and the upper wall plate); the ventilation area S2 of the vent pipe section when the vent device is not installed is π * d 2 / 4 (where d is the first inner diameter), when the floating ventilation component 3 reaches the upper limit position, the ventilation area S1 above the ventilation port device reaches its minimum.

[0073] In a preferred embodiment, the vent device of the present invention can be designed as follows:

[0074] When the floating ventilated component 3 is in the lower limit position, it should satisfy S1≥S2, that is, π*D*H≥π*d 2 / 4, such that the distance H between the upper opening of its through hole and the upper wall plate 10 satisfies: H*D≥d 2 / 4, to ensure that the vent device has full ventilation capacity when the oil level is low, without affecting the ventilation performance of the original venting pipeline.

[0075] When the floating ventilated component 3 is in the upper limit position, S1 ≥ S2 * k should be satisfied, where k is the ventilation conversion factor, preferably 0.5 ≤ k < 1, more preferably k = 0.8. When k = 0.8, that is, π * D * H ≥ π * d 2 / 4*0.8, so that the distance H between the upper opening of its through hole and the upper wall plate 10 satisfies: H*D≥d 2 / 5, so that when the fuel level A in the fuel tank is at a high level for a short time, the vent device can still ensure that the fuel tank has a certain ventilation capacity, so as to avoid the fuel tank being pressurized.

[0076] After installing this vent device, the height preventing fuel from overflowing into the vent line can be increased, thereby extending the fuel tank venting time. When the fuel level A rises from the low fuel level to the high fuel level, the floating vent member 3 rises with the fuel level A, raising the inlet height of the vent line 1 and keeping it above the fuel level. When the floating vent member 3 rises to its upper limit position, the fuel level A is already close to the upper wall plate 10 of the fuel tank. If the fuel level A continues to rise, it will enter the vent line through the vent. When the fuel level begins to drop, the floating vent member 3 will then drop accordingly.

[0077] The above detailed description illustrates the working principle of this vent device. This vent device has a simple structure and is easy to install. While ensuring the venting performance of the fuel tank, it also retains the fuel flow capacity of the venting pipeline to meet certain flow requirements, so that the fuel tank has better venting performance and economy.

Claims

1. A breather port device for an oil tank, characterized by, The vent device includes: Ventilation pipe (1), the ventilation pipe includes a port section (2), the port section (2) extends toward the upper wall plate (10) of the oil tank, the port section has a first inner diameter; A floating vent member (3) is provided with an axially extending through hole and is arranged around the pipe section (2) such that the pipe section (2) is located within the through hole, and the floating vent member (3) is configured to float along the pipe section (2) as the fuel level (A) in the fuel tank changes, wherein the upper orifice of the floating vent member (3) is kept not lower than the opening of the pipe section (2) adjacent to the fuel level (A) in the fuel tank and floats relative to the opening; A limiting structure (4) is provided at the nozzle section (2) and configured to restrict the floating venting member (3) to between its upper and lower limit positions when the member floats. The vent device is designed as follows: when the floatable ventilation member (3) is in the lower limit position, the distance between the upper hole of the through hole and the upper wall plate (10) satisfies: H D ≥ d 2 / 4, When the floatable ventilation member (3) is in the upper limit position, the distance between the upper hole of the through hole and the upper wall plate (10) satisfies: H D ≥ d 2 / 5, Wherein, H is the distance between the upper opening of the through hole and the upper wall plate, D is the inner diameter of the upper opening of the through hole, and d is the first inner diameter of the pipe section (2).

2. The vent device of claim 1, wherein The floating ventilation component (3) has an upper stop (5) protruding inward toward the ventilation duct (1) and a lower stop (6) below the upper stop, wherein, at the upper limit position, the limiting structure (4) contacts the lower stop (6), and at the lower limit position, the limiting structure (4) contacts the upper stop (5).

3. The vent device of claim 2, wherein, The inner diameter of the portion of the through hole between the upper stop (5) and the lower stop (6) is greater than the inner diameter of the upper opening and the inner diameter of the lower opening of the through hole.

4. The vent device of claim 3, wherein The limiting structure (4) is configured as an annular flange surrounding the port section (2) of the ventilation pipe (1).

5. The vent device according to claim 4, characterized in that, When the fuel level (A) in the fuel tank drops to the lower limit position of the floating vent member (3), the upper surface of the annular flange engages with the lower surface of the upper stop (5); when the fuel level (A) in the fuel tank rises to the upper limit position of the floating vent member (3), the lower surface of the annular flange engages with the upper surface of the lower stop (6).

6. The vent device of claim 5, wherein, The lower surface of the limiting structure (4) and the upper surface of the lower stop (6) are inclined accordingly. When the fuel level (A) in the fuel tank rises to the point that the floating vent member (3) reaches the upper limit position, the lower surface of the limiting structure (4) and the upper surface of the lower stop (6) are inclined to help with the sealing when they are joined.

7. The vent device of claim 1, wherein The limiting structure (4) is integrally disposed at or fixedly connected to the port section (2) of the ventilation pipeline (1).

8. The vent device of claim 7, wherein, The floating ventilator (3) includes a housing, which may be solid or hollow.

9. The vent device of claim 8, wherein, The top outer surface of the housing of the floating venting member is inclined to allow fuel in the tank to flow down along the top outer surface of the housing.

10. A fuel tank for an aircraft, the fuel tank comprising a vent device according to any one of the preceding claims.

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