An electrostatic protection structure for aircraft fuel tank

Abstract

The invention discloses an electrostatic protection structure for an aircraft fuel tank, comprising a film layer, an aluminum mesh layer, a copper mesh layer, and a carbon fiber unidirectional tape, which are sequentially laid from bottom to top according to a general composite material laying process, wherein the aluminum mesh layer comprises a first aluminum mesh layer and a second aluminum mesh layer, the first aluminum mesh layer is installed on the fuel tank filling port cover, the copper mesh layer comprises a first copper mesh layer and a second copper mesh layer, the first copper mesh layer and the second copper mesh layer are respectively connected to the first aluminum mesh layer and the second aluminum mesh layer, the first copper mesh layer and the second copper mesh layer are connected with a carbon fiber unidirectional tape, and the second aluminum mesh layer is connected to the zero potential point of the aircraft, so that an electrical path for electrostatic derivation is formed between the fuel tank and the zero potential point of the aircraft. The invention has the advantages of improving the electrostatic protection efficiency and production efficiency of the fuel tank, reducing external overlapping components, and reducing manufacturing costs.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft, and in particular relates to an electrostatic protection structure for an aircraft fuel tank. Background Art

[0002] For composite structures on aircraft, especially aircraft fuel tanks, due to their high resistance and low thermal conductivity, and the low operating temperature of the matrix material of polymer-based composite materials (generally not exceeding 80°C), polymer-based composite structures are extremely sensitive to high voltage, high current, large coulomb (continuous high current) and sparks caused by lightning strikes. Lightning strikes can easily cause damage to such structures, resulting in catastrophic consequences. In addition, during the service of the aircraft, a large amount of static electricity is easily generated inside the composite integral tank, especially during maneuvering flight, when the fuel and the inner wall of the composite integral structure tank or other internal fuel system components are subjected to severe friction, collision, splashing, etc. During refueling and other use of the aircraft, the fuel in the wing tank is always in a vibrating state and the fuel itself will also be stirred. Since composite materials themselves are poor conductors of electricity, the static electricity leakage rate is slow. If the static electricity protection design of the composite structure is not appropriate, it is easy to cause a large amount of static electricity accumulation. When static electricity accumulates to a certain level and there are sensitive conditions in the fuel tank that may cause static electricity discharge (such as the tip of a fuel system component), the static electricity discharge may trigger a discharge spark, ignite the mixture of fuel vapor and air, and cause catastrophic accidents such as fuel tank explosion or fire.

[0003] For safety and risk considerations, Articles 23.867 and 23.954 of the Airworthiness Regulations for Normal, Utility, Acrobatic and Commuter Category Aircraft (CCAR23R3) stipulate lightning protection design requirements for aircraft fuselage structures and fuel systems, which are roughly divided into lightning direct effect protection design and electrostatic protection design requirements. For composite integral structure fuel tanks, it is usually considered to arrange the fuel tanks in areas with low probability of lightning attachment, that is, lightning strike zone 3, during the overall structural layout stage. Although the probability of lightning directly attaching to components arranged in lightning strike zone 3 is low, the components in lightning strike zone 3 still need to have the ability to conduct large currents. The electrostatic protection design of composite integral structure fuel tanks generally considers two aspects, namely, taking measures to reduce the generation of static electricity and taking measures to accelerate the dissipation of static electricity. Traditional anti-static protection methods and processes for fuel tanks mainly include applying flame sprayed aluminum layers on the inner wall of the fuel tank, spraying anti-static coating layers, and hanging metal mesh in the fuel tank. The traditional method has the disadvantages of poor electrostatic protection efficiency, requiring many parts to be overlapped externally, which makes the implementation cost high and increases the weight of the aircraft, and has problems such as difficult process, complicated operation and long production cycle. Summary of the invention

[0004] The purpose of the present invention is to solve the problems in the background technology and to propose an electrostatic protection structure for an aircraft fuel tank, which can improve the electrostatic protection efficiency and production efficiency of the fuel tank, reduce external overlapped components, and reduce manufacturing costs.

[0005] To achieve the above-mentioned purpose, the present invention proposes an aircraft fuel tank electrostatic protection structure, comprising a film layer, an aluminum mesh layer, a copper mesh layer, and a carbon fiber unidirectional tape, which are laid in sequence from bottom to top according to a general composite material laying process, the aluminum mesh layer comprises a first aluminum mesh layer and a second aluminum mesh layer, the first aluminum mesh layer is installed on the fuel tank filler cap, the copper mesh layer comprises a first copper mesh layer and a second copper mesh layer, the first copper mesh layer and the second copper mesh layer are connected to the first aluminum mesh layer and the second aluminum mesh layer respectively, the first copper mesh layer and the second copper mesh layer are connected with a carbon fiber unidirectional tape, and the second aluminum mesh layer is connected to the zero potential point of the aircraft, so that an electrical path for static electricity conduction is formed between the fuel tank and the zero potential point of the aircraft.

[0006] Preferably, the left and right edges of the adhesive film layer are 18.5-19.5 mm wider than the left and right edges of the copper mesh layer, respectively.

[0007] Preferably, the left and right edges of the adhesive film layer are 19.05 mm wider than the left and right edges of the copper mesh layer.

[0008] Preferably, the first copper mesh layer and the second copper mesh layer are both in a square shape.

[0009] Preferably, the sizes of the first copper mesh layer and the second copper mesh layer are both 50.80 mm×50.80 mm.

[0010] Preferably, the aluminum mesh layer is laid according to the requirements of the main lightning current conduction path in the lightning strike area.

[0011] Preferably, the carbon fiber unidirectional tape is laid according to the requirements of the electrostatic conduction path.

[0012] Preferably, the copper mesh layer is laid according to lightning current overlapping requirements and electrochemical corrosion prevention requirements.

[0013] Preferably, the adhesive film layer, the aluminum mesh layer, the copper mesh layer, and the carbon fiber unidirectional tape are laid in sequence from bottom to top according to a general composite material laying process and then cured according to general composite material curing requirements.

[0014] Preferably, the adhesive film layer, the aluminum mesh layer, the copper mesh layer, and the carbon fiber unidirectional tape are cured at the same temperature.

[0015] Beneficial effects of the present invention:

[0016] 1. Use one-piece molding technology to improve the overall electrostatic protection efficiency, production efficiency and surface processing quality of the fuel tank, effectively improve the anti-static inspection efficiency of the fuel tank, speed up the development progress of general aircraft, and reduce development costs.

[0017] 2. Utilize and protect the fuel tank filler cap, and only place static protection / conductive layers on the fuel tank to avoid the use of a large number of external overlapping components, effectively reducing procurement costs and aircraft weight.

[0018] 3. No special manufacturing equipment is required, only conventional cutting equipment or simple cutting tools are needed, which greatly saves manufacturing costs.

[0019] 4. All electrostatic lap joint technologies are based on ply design. Therefore, when design requirements change, only the ply size needs to be updated without major changes in the design, paving mold, process parameters, etc., which greatly reduces the cost of design changes.

[0020] The features and advantages of the present invention will be described in detail through embodiments in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the installation structure of an embodiment of the present invention.

[0022] Figure 2 It is a schematic structural diagram of an embodiment of the present invention.

[0023] Figure 3 It is a schematic diagram of the paving state of an embodiment of the present invention.

[0024] In the figure: 1-adhesive film layer, 2-aluminum mesh layer, 3-copper mesh layer, 4-carbon fiber unidirectional tape, 5-paving mold, 21-second aluminum mesh layer, 22-first aluminum mesh layer, 31-second copper mesh layer, 32-first copper mesh layer. DETAILED DESCRIPTION

[0025] See also Figure 1 , Figure 2 , Figure 3The present embodiment provides an aircraft fuel tank electrostatic protection structure, comprising a film layer 1, an aluminum mesh layer 2, a copper mesh layer 3, and a carbon fiber unidirectional tape 4, which are sequentially laid from bottom to top according to a general composite material laying process, wherein the aluminum mesh layer 2 comprises a first aluminum mesh layer 22 and a second aluminum mesh layer 21, and the first aluminum mesh layer 22 is installed on the fuel tank filler cap, and the copper mesh layer 3 comprises a first copper mesh layer 32 and a second copper mesh layer 31, and the first copper mesh layer 32 and the second copper mesh layer 31 are connected to the first aluminum mesh layer 22 and the second aluminum mesh layer 21 respectively, and the first copper mesh layer 32 and the second copper mesh layer 31 are connected by a carbon fiber unidirectional tape 4, and the second aluminum mesh layer 21 is connected to the aircraft The zero potential point of the fuel tank is connected to the zero potential point of the aircraft, so that an electrical path for static electricity conduction is formed between the fuel tank and the zero potential point of the aircraft. The paving mold 5 is surface treated when paving is performed according to the general composite material paving process. The layout design of the film layer 1 is determined according to the design of the copper mesh layer 3 to ensure that the surface after curing is flat and smooth. The aluminum mesh layer 2 and the copper mesh layer 3 are respectively an extended aluminum mesh and an extended copper mesh. In actual use, the static electricity generated by the fuel tank is conducted to the zero potential point of the aircraft along the first aluminum mesh layer 22, the first copper mesh layer 32, the carbon fiber unidirectional tape 4, the second copper mesh layer 31, and the first aluminum mesh layer 22, thereby realizing the static electricity conduction of the fuel tank.

[0026] The left and right edges of the adhesive film layer 1 are 18.5 to 19.5 mm wider than the left and right edges of the copper mesh layer 3. Preferably, the left and right edges of the adhesive film layer 1 are 18.5 to 19.5 mm wider than the left and right edges of the copper mesh layer 3 to prevent the copper mesh layer from being exposed.

[0027] The first copper mesh layer 32 and the second copper mesh layer 31 are both in a square shape, and the size of the first copper mesh layer 32 and the second copper mesh layer 31 are both 50.80 mm×50.80 mm.

[0028] The aluminum mesh layer 2 is laid according to the requirements of the main lightning current conduction path in the lightning strike area.

[0029] The carbon fiber unidirectional tape 4 is laid according to the requirements of the electrostatic conduction path.

[0030] The copper mesh layer 3 is laid according to the lightning current overlapping requirements and the electrochemical corrosion prevention requirements to avoid electrochemical corrosion of the copper mesh layer 3.

[0031] The adhesive film layer 1, the aluminum mesh layer 2, the copper mesh layer 3, and the carbon fiber unidirectional tape 4 are laid in sequence from bottom to top according to a general composite material laying process and then cured according to the general composite material curing requirements.

[0032] The curing temperatures of the adhesive film layer 1, the aluminum mesh layer 2, the copper mesh layer 3, and the carbon fiber unidirectional tape 4 are kept consistent during curing.

[0033] The manufacturing process of the electrostatic protection structure of the aircraft fuel tank includes the following steps:

[0034] Step 1: Complete the layout design of the 2-layer aluminum mesh according to the main lightning current conduction path requirements in the lightning strike area;

[0035] Step 2: Complete the layout design of the carbon fiber unidirectional tape 4 layers according to the requirements of the electrostatic conduction path;

[0036] Step 3: Complete the copper mesh layer 3 layout design according to the lightning current bonding requirements and electrochemical corrosion prevention requirements;

[0037] Step 4, completing the layout design of the film layer 1 according to the copper mesh layer 3 laying design;

[0038] Step 5, performing surface treatment on the paving mold 5 according to the general composite material paving requirements;

[0039] Step 6: Lay the adhesive film layer 1, the aluminum mesh layer 2, the copper mesh layer 3, and the carbon fiber unidirectional tape 4 in sequence according to the general composite material laying requirements;

[0040] Step seven, complete the integral curing and molding of the parts according to the general composite material curing requirements.

[0041] The above embodiments are intended to illustrate the present invention, not to limit the present invention. Any solution that is a simple transformation of the present invention belongs to the protection scope of the present invention.

Claims

1. An aircraft fuel tank electrostatic protection structure, characterized in that: The invention comprises a film layer, an aluminum mesh layer, a copper mesh layer and a carbon fiber unidirectional tape which are sequentially laid from bottom to top according to a general composite material laying process. The aluminum mesh layer comprises a first aluminum mesh layer and a second aluminum mesh layer. The first aluminum mesh layer is installed on the fuel tank filler cap. The copper mesh layer comprises a first copper mesh layer and a second copper mesh layer. The first copper mesh layer and the second copper mesh layer are connected to the first aluminum mesh layer and the second aluminum mesh layer respectively. The first copper mesh layer and the second copper mesh layer are connected with a carbon fiber unidirectional tape. The second aluminum mesh layer is connected to the zero potential point of the aircraft, so that an electrical path for static electricity conduction is formed between the fuel tank and the zero potential point of the aircraft.

2. The aircraft fuel tank electrostatic protection structure according to claim 1, characterized in that: The left and right edges of the adhesive film layer are respectively 18.5-19.5 mm wider than the left and right edges of the copper mesh layer.

3. The aircraft fuel tank electrostatic protection structure according to claim 2, characterized in that: The left and right edges of the adhesive film layer are respectively 19.05 mm wider than the left and right edges of the copper mesh layer.

4. The aircraft fuel tank electrostatic protection structure according to claim 1, characterized in that: The first copper mesh layer and the second copper mesh layer are both in a square shape.

5. The aircraft fuel tank electrostatic protection structure according to claim 1 or 4, characterized in that: The sizes of the first copper mesh layer and the second copper mesh layer are both 50.80 mm×50.80 mm.

6. The aircraft fuel tank electrostatic protection structure according to claim 1, characterized in that: The aluminum mesh layer is laid according to the requirements of the main lightning current conduction path in the lightning strike area.

7. The aircraft fuel tank electrostatic protection structure according to claim 1, characterized in that: The carbon fiber unidirectional tape is laid according to the requirements of the electrostatic conduction path.

8. The aircraft fuel tank electrostatic protection structure according to claim 1, characterized in that: The copper mesh layer is laid according to the lightning current overlapping requirements and the electrochemical corrosion prevention requirements.

9. The aircraft fuel tank electrostatic protection structure according to claim 1, characterized in that: The adhesive film layer, the aluminum mesh layer, the copper mesh layer, and the carbon fiber unidirectional tape are laid in sequence from bottom to top according to a general composite material laying process and then cured according to general composite material curing requirements.

10. The aircraft fuel tank electrostatic protection structure according to claim 9, characterized in that: The curing temperature of the adhesive film layer, the aluminum mesh layer, the copper mesh layer and the carbon fiber unidirectional tape is kept consistent when curing.

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