Composite fuel tank of aircraft and design method of composite fuel tank

Abstract

The invention discloses an aircraft composite material oil tank and a design method thereof in the technical field of composite material oil tanks. The aircraft composite material oil tank comprises multiple oil tank barrel sections, an oil tank connecting frame, an end face sealing plate, an internal partition frame and a covering cap. The multiple oil tank sections are connected through oil tank connecting frames. The oil tank connecting frame is sleeved with the front and rear oil tank barrel sections; a plurality of internal bulkheads are arranged in the plurality of oil tank sections; the internal bulkhead is connected with the inner wall of the oil tank barrel section in a riveting and sealing manner; the covering cap is arranged at the front ends of the multiple oil tank barrel sections; the rear ends of the multiple oil tank barrel sections are sealed through end face sealing plates. An outer skin is further bonded to the whole tank body of the multiple oil tank barrel sections. The oil tank is segmented in the length direction and is divided into a multi-segment structure to be assembled and connected; production and manufacturing of the oil tank with the special-shaped section are achieved, installation and sealing of internal pipelines of the oil tank are guaranteed, and the overload requirements under various flight working conditions are met.

Description

Technical Field

[0001] The invention relates to the technical field of composite fuel tanks, and in particular to an aircraft composite fuel tank and a design method thereof. Background Art

[0002] At present, there are two main types of fuel tank materials used in aircraft, aluminum alloy and composite materials. Aluminum alloy has the characteristics of high strength and good high and low temperature resistance. Compared with aluminum alloy fuel tanks, composite fuel tanks have the advantages of light weight while having comparable strength and stiffness. However, composite fuel tanks are usually difficult to make due to mold making and demoulding. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides an aircraft composite fuel tank and a design method thereof, which can realize the production and manufacturing of special-section fuel tanks, ensure the installation and sealing of their internal pipelines, and meet the overload requirements under various flight conditions.

[0004] The object of the present invention is achieved in one aspect as follows: A design method for an aircraft composite fuel tank comprises the following steps: 1) First, the three sections of the fuel tank barrel, the fuel tank connection frame, the internal partition frame and the cover are formed by a mold, and the fuel tank end face sealing plate is machined and then assembled and installed; 2) Internal bulkhead connection: Install the bulkhead inside the fuel tank, split the bulkhead into two parts, and connect them through the bulkhead connecting plate; on the outside of the fuel tank, make the connection holes between the bulkhead and the fuel tank skin according to the position of the bulkhead, and connect them with fasteners; 3) Fuel tank segment socketing and positioning: Use the assembly tool to position the polished and socketed fuel tank segment, and the positioning card plate fits the fuel tank without gap; the end face of the first fuel tank segment is positioned by the tool end face positioning block, and the fuel tank connection frame, fuel tank segment 2, fuel tank connection frame, fuel tank segment 3, and end face sealing plate are fixed to the assembly tool in sequence, and the end face sealing plate locating block is used to position the end face sealing plate belly plate surface; fix the outer shape card plate in place to ensure the relative position of the entire fuel tank; 4) Making connection holes: After the tooling card has positioned the parts, make the connection holes between the tank section and the tank connection frame, the tank connection plate and the tank section, and the tank section and the end face partition; 5) Fuel pipeline assembly: according to the theoretical position of the digital model, make the air holes, oil holes and joint holes of each bulkhead; seal and install the pipeline joints on the end bulkhead, connect the pipeline, and use clamps to fix the pipeline on the bulkhead to ensure that the pipeline does not shake; 6) Oil tank sealing connection: Roughen and clean the joint position of the oil tank section, apply sealant to the joint surface of the oil tank section, the oil tank connection frame and the oil tank connection plate, and position them on the tooling, use fasteners to connect, then apply sealant to the oil tank section 2 and the oil tank connection frame, fit them together, and position them through the tooling, wet install the fasteners, and connect all the oil tanks in this order; when the oil tanks are connected in sequence, fillet the corners and seal the nail heads at each connection position; 7) Installation of the fuel tank cover: Place the cover frame into the fuel tank opening, make the connecting holes, fit the cover to the skin opening, and make the connecting holes between the cover and the cover frame; install the support plate nuts at the holes on the cover frame that will be connected to the cover; apply sealant to the fitting surface of the frame and the fuel tank, and connect them with rivets; apply sealant around the frame, and connect the cover with countersunk screws.

[0005] As a further limitation of the present invention, the three oil tank barrel sections in step 1) are formed by a male mold, and the oil tank connecting frame is formed by a female mold.

[0006] As a further limitation of the present invention, in step 2), the bulkhead connecting plate is positioned at the bulkhead corner, and after the position of the bulkhead connecting plate is determined, connecting holes between the bulkhead connecting plate and the bulkhead are made and connected using blind rivets.

[0007] Another aspect of the purpose of the present invention is achieved as follows: an aircraft composite fuel tank comprises a plurality of fuel tank barrel sections, a fuel tank connecting frame, an end face sealing plate, an internal bulkhead frame and a mouth cover; the plurality of fuel tank sections are connected via a fuel tank connecting frame; the fuel tank connecting frame is sleeved with the front and rear fuel tank barrel sections; a plurality of internal bulkhead frames are arranged in the plurality of fuel tank sections; the internal bulkhead frames are connected to the inner wall of the fuel tank barrel section by riveting and sealing; the mouth cover is arranged at the front end of the plurality of fuel tank barrel sections; the rear end of the plurality of fuel tank barrel sections is sealed by an end face sealing plate; an outer skin is also bonded to the entire tank body of the plurality of fuel tank barrel sections.

[0008] As a further limitation of the present invention, the multi-section fuel tank barrel section includes fuel tank section one, fuel tank section two and fuel tank section three; the fuel tank section one has a closed front end face and an open rear end face; the front and rear end faces of the fuel tank section two and fuel tank section three are both open structures.

[0009] As a further limitation of the present invention, the oil tank connecting frame is respectively sleeved with the front and rear oil tank barrel sections, and each oil tank barrel section is sleeved 20 mm.

[0010] As a further limitation of the present invention, the oil tank connection frame is provided with an oil hole at the bottom and an air hole at the top; and the oil tank connection frame is provided with an oil tank connection plate.

[0011] As a further limitation of the present invention, the internal bulkhead is a disconnected structure, which is connected by a bulkhead connecting plate; the top connecting gap of the internal bulkhead serves as a vent hole, and the bottom of the internal bulkhead is provided with an oil hole.

[0012] As a further limitation of the present invention, the end face sealing plate is made of aluminum alloy, has a thickness of 2 mm and a flange length of 40 mm; the outer side surface and bottom surface of the end face sealing plate bonded to the outer skin are connected by countersunk rivets, and the inner side surface and top surface are connected by semi-circular head rivets.

[0013] As a further limitation of the present invention, the outer side and the bottom of the multi-section fuel tank barrel section are connected to the outer skin by countersunk rivets, and the inner side and the top are connected by semi-circular head rivets.

[0014] Compared with the prior art, the beneficial effects of the present invention are: the present invention manufactures the fuel tank barrel section in sections, the parts structure is simple, and the cost and difficulty of parts manufacturing can be effectively reduced; the internal bulkhead is simple to install and easy to seal, and can effectively control the deformation effect of the aircraft load on the fuel tank under various working conditions; the internal bulkhead can be increased or reduced according to the aircraft in different working conditions, and it has strong adaptability.

[0015] Every two sections of the fuel tank are connected by a composite connecting frame. The connecting frame is formed by a negative mold to ensure the surface of the fuel tank socket section, which is easy to socket and reduces the amount of assembly and polishing. At the same time, the connecting plate of the fuel tank connecting frame can provide a baffle for the inside of the fuel tank, limit the violent shaking of the fuel, and play a role in stopping waves. The segmented assembly can ensure the cover and sealing quality of each internal bulkhead and connecting frame. The use of composite materials with low density can achieve lightweight requirements and reduce the overall structural weight. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0017] Figure 1 Schematic diagram of the fuel tank segmentation of the present invention.

[0018] Figure 2 Schematic diagram of the segmented connection of the oil tank of the present invention.

[0019] Figure 3 Schematic diagram of the oil tank connection frame structure of the present invention.

[0020] Figure 4 Schematic diagram of the installation of the internal bulkhead of the present invention.

[0021] Figure 5 Schematic diagram of the internal bulkhead structure of the fuel tank of the present invention.

[0022] Figure 6 A side view of a section of a fuel tank according to the present invention.

[0023] Figure 7 Cross-sectional view of the present invention taken along line AA.

[0024] Figure 8 A schematic diagram of the connection between the mouth frame and the mouth cover of the present invention.

[0025] Fig. 9 Schematic diagram of the end face sealing plate of the present invention.

[0026] Among them, 1 is the first section of the oil tank, 2 is the second section of the oil tank, 3 is the third section of the oil tank, 4 is the connecting frame of the oil tank, 4-1 is the connecting plate of the oil tank, 4-2 is the air vent, 4-3 is the oil hole; 5 is the internal bulkhead frame, 5-1 is the bulkhead connecting plate, 5-2 is the oil hole; 6 is the mouth cover, 6-1 is the mouth frame, 7 is the end face sealing plate. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] A design method for an aircraft composite fuel tank comprises the following steps: 1) First, the three-section fuel tank barrel section, fuel tank connection frame, internal partition frame and cover are formed by molds, and the fuel tank end face sealing plate is machined, and then assembled and installed; the three-section fuel tank barrel section is formed by a positive mold, and the fuel tank connection frame is formed by a negative mold to ensure the surface of the fuel tank sleeve section, which is easy to sleeve and reduce the amount of assembly grinding; 2) Internal bulkhead connection: Install the bulkhead inside the fuel tank, split the bulkhead into two parts, and connect them through the bulkhead connecting plate; the bulkhead connecting plate is positioned at the corner of the bulkhead, and after the position of the bulkhead connecting plate is determined, the connecting holes between the bulkhead connecting plate and the bulkhead are made, and connected with blind rivets; on the outside of the fuel tank, according to the position of the bulkhead, the connecting holes and countersinks between the bulkhead and the fuel tank skin are made, and rivets and screws are used to connect them; 3) Fuel tank segment socketing and positioning: Use the assembly tool to position the polished and socketed fuel tank segment, and the positioning card plate fits the fuel tank without gap; the end face of the first fuel tank segment is positioned by the tool end face positioning block, and the fuel tank connection frame, fuel tank segment 2, fuel tank connection frame, fuel tank segment 3, and end face sealing plate are fixed to the assembly tool in sequence, and the end face sealing plate locating block is used to position the end face sealing plate belly plate surface; fix the outer shape card plate in place to ensure the relative position of the entire fuel tank; 4) Making connection holes: After the tooling pallet has positioned the parts, make the connection holes and countersinks between the tank section and the tank connection frame, between the tank connection plate and the tank section, and between the tank section and the end face partition; 5) Fuel pipeline assembly: according to the theoretical position of the digital model, make the air holes, oil holes and joint holes of each bulkhead; seal and install the pipeline joints on the end bulkhead, connect the pipeline, and use clamps to fix the pipeline on the bulkhead to ensure that the pipeline does not shake; 6) Oil tank sealing connection: Roughen and clean the joint position of the oil tank section, apply sealant to the joint surface of the oil tank section, the oil tank connection frame and the oil tank connection plate, and position them on the tooling, use fasteners to connect, then apply sealant to the oil tank section 2 and the oil tank connection frame, fit them together, and position them through the tooling, wet install the fasteners, and connect all the oil tanks in this order; when the oil tanks are connected in sequence, fillet the corners and seal the nail heads at each connection position; 7) Installation of the fuel tank cover: Place the cover frame inside the fuel tank opening and make the connection hole; fit the cover to the skin opening to ensure the butt clearance and make the connection hole between the cover and the cover frame; install the support plate nut at the hole on the frame that will be connected to the cover to ensure that the cover is removable. Apply sealant to the fitting surface of the frame and the fuel tank and connect them with rivets. Apply sealant around the frame and connect the cover with countersunk screws.

[0029] like Figure 1 As shown, a composite fuel tank for aircraft has a front-end closing and a concave special-shaped structure in the middle. The fuel tank is segmented in the length direction and is assembled and connected in a multi-segment structure. The fuel tank is respectively spliced ​​by three small fuel tanks. Considering the easy demoulding of the fuel tank, the arrangement of the T-shaped ribs and the installation of the fuel pipe, the length of each small fuel tank is about 400mm~500mm to ensure its operability. Specifically, it includes a multi-section fuel tank barrel section, a fuel tank connecting frame 4, an end face sealing plate 7, an internal partition frame 5 and a cover 6; the multi-section fuel tank sections are connected by the fuel tank connecting frame 4; the fuel tank connecting frame 4 is sleeved with the front and rear fuel tank barrel sections; a plurality of internal partition frames 5 are arranged in the multi-section fuel tank section; the internal partition frame 5 is connected to the inner wall of the fuel tank barrel section by riveting and sealing; the cover 6 is arranged at the front end of the multi-section fuel tank barrel section; the rear end of the multi-section fuel tank barrel section is sealed by the end face sealing plate 7; the entire box body of the multi-section fuel tank barrel section is also bonded with an outer skin; the outer side and bottom of the multi-section fuel tank barrel section are bonded to the outer skin using countersunk rivets HB6316 to ensure surface fit, and the inner side and top use semi-circular head rivets HB6231 to optimize the force form and reduce the workload of countersinking during assembly.

[0030] The oil tank structure is a circumferentially wrapped "barrel-shaped" structure, and the multiple oil tank barrel sections include oil tank section one 1, oil tank section two 2 and oil tank section three 3; oil tank section one 1 is a structure with a closed front end face and an open rear end face; oil tank section two 2 and oil tank section three 3 are both open structures in terms of front and rear end faces; the demoulding property of each oil tank section is ensured.

[0031] like Figure 2-3 As shown, the fuel tank connection frame 4 is respectively connected with the front and rear fuel tank barrel sections, and each fuel tank barrel section is inserted 20mm; the connection surface is coated with sealant and then connected, and then sealed by rivets. The fuel tank connection frame is made of composite material, with a thickness of 2mm and a flange length of 40mm. A φ15mm oil hole 4-3 is opened at the bottom of the fuel tank connection frame 4, and a φ10mm air hole 4-2 is opened at the top to ensure the oil circulation inside the fuel tank. A fuel tank connection plate 4-1 is set on the fuel tank connection frame 4; the fuel tank connection plate 4-1 can provide a barrier for the inside of the fuel tank, limit the violent shaking of the fuel, and play a role in stopping waves; and pipe holes can be opened on the connection plate according to different fuel pipeline forms.

[0032] like Figure 4-5 As shown, multiple T-shaped internal bulkheads 5 are arranged inside the oil tank according to needs, and the structural thickness is 2mm. The internal bulkhead 5 is connected to the inner wall of the oil tank by riveting and sealing. In order to ensure the surface sealing of the internal bulkhead 5, the internal bulkhead 5 is a disconnected structure, which is connected by a bulkhead connecting plate 5-1, and the bulkhead connecting plate 5-1 is fixed by blind rivets. The top connecting gap of the internal bulkhead 5 is used as a vent, and a φ15mm oil hole 5-2 is opened at the bottom of the internal bulkhead for oil communication.

[0033] like Figure 6-8As shown, considering the installation of the oil pipe joint and the operability of the fillet seal of the oil tank connecting plate, a cover 6 structure is designed at the front end of the front oil tank. The thickness of the cover 6 and the frame 6-1 is consistent with the thickness of the oil tank, both of which are 2mm. The frame 6-1 and the oil tank are connected with semi-circular head rivets, and the cover 6 and the frame 6-1 are connected with GB933 airtight support plate nuts GB933 and semi-circular head screws.

[0034] like Fig. 9 As shown, the rear end face of the fuel tank is sealed by the fuel tank end face sealing plate 7, the end face sealing plate 7 is made of 7075 aluminum alloy, has a thickness of 2mm, and a flange length of 40mm; the flange has a variable cross-section, and can be connected to the fuel tank and the skin at the same time, thereby optimizing the force transmission path of the entire body structure; the outer side and bottom surfaces of the end face sealing plate 7 bonded to the outer skin are connected by countersunk rivets, and the inner side and top surfaces are connected by semicircular head rivets.

[0035] The present invention provides an aircraft composite fuel tank, which has a closed front end and a concave special-shaped structure in the middle. The fuel tank is segmented in the length direction and is divided into a multi-segment structure for assembly and connection. The fuel tank is respectively formed by splicing three small fuel tanks. The internal bulkhead is easy to install and seal, and can effectively control the deformation effect of the load of the aircraft under various working conditions on the fuel tank. The internal bulkhead can be increased or reduced according to the aircraft in different working conditions, and the adaptability is strong. Every two sections of the fuel tank are connected by a composite connecting frame, and the connecting frame is formed by a female mold to ensure the profile of the fuel tank sleeve section, which is easy to sleeve and reduces the amount of assembly and grinding. The production of special-shaped cross-section fuel tanks is realized, and the internal pipelines are ensured to be installed and sealed, and the overload requirements under various flight conditions are met.

[0036] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A design method for an aircraft composite fuel tank, characterized in that: The following steps are involved: 1) First, the three sections of the fuel tank barrel, the fuel tank connection frame, the internal partition frame and the cover are formed by a mold, and the fuel tank end face sealing plate is machined and then assembled and installed; 2) Internal bulkhead connection: Install the bulkhead inside the fuel tank, split the bulkhead into two parts, and connect them through the bulkhead connecting plate; on the outside of the fuel tank, make the connection holes between the bulkhead and the fuel tank skin according to the position of the bulkhead, and connect them with fasteners; 3) Fuel tank segment socketing and positioning: Use the assembly tool to position the polished and socketed fuel tank segment, and the positioning card plate fits the fuel tank without gap; the end face of the first fuel tank segment is positioned by the tool end face positioning block, and the fuel tank connection frame, fuel tank segment 2, fuel tank connection frame, fuel tank segment 3, and end face sealing plate are fixed to the assembly tool in sequence, and the end face sealing plate locating block is used to position the end face sealing plate belly plate surface; fix the outer shape card plate in place to ensure the relative position of the entire fuel tank; 4) Making connection holes: After the tooling card has positioned the parts, make the connection holes between the tank section and the tank connection frame, the tank connection plate and the tank section, and the tank section and the end face partition; 5) Fuel pipeline assembly: according to the theoretical position of the digital model, make the air holes, oil holes and joint holes of each bulkhead; seal and install the pipeline joints on the end bulkhead, connect the pipeline, and use clamps to fix the pipeline on the bulkhead to ensure that the pipeline does not shake; 6) Oil tank sealing connection: Roughen and clean the joint position of the oil tank section, apply sealant to the joint surface of the oil tank section, the oil tank connection frame and the oil tank connection plate, and position them on the tooling, use fasteners to connect, then apply sealant to the oil tank section 2 and the oil tank connection frame, fit them together, and position them through the tooling, wet install the fasteners, and connect all the oil tanks in this order; when the oil tanks are connected in sequence, fillet the corners and seal the nail heads at each connection position; 7) Installation of the fuel tank cover: Place the cover frame into the fuel tank opening, make the connecting holes, fit the cover to the skin opening, and make the connecting holes between the cover and the cover frame; install the support plate nuts at the holes on the cover frame that will be connected to the cover; apply sealant to the fitting surface of the frame and the fuel tank, and connect them with rivets; apply sealant around the frame, and connect the cover with countersunk screws.

2. The design method of an aircraft composite fuel tank according to claim 1, characterized in that: The three oil tank barrel sections in step 1) are formed by a male mold, and the oil tank connecting frame is formed by a female mold.

3. The design method of an aircraft composite fuel tank according to claim 1, characterized in that: The bulkhead connecting plate described in step 2) is positioned at the bulkhead corner. After the position of the bulkhead connecting plate is determined, connecting holes between the bulkhead connecting plate and the bulkhead are made and connected using blind rivets.

4. An aircraft composite fuel tank, characterized in that: It includes multiple sections of fuel tank barrel, fuel tank connecting frame, end face sealing plate, internal partition frame and mouth cover; the multiple sections of fuel tank barrel are connected by the fuel tank connecting frame; the fuel tank connecting frame is sleeved with the front and rear fuel tank barrel sections; multiple internal partition frames are arranged in the multiple sections of fuel tank; the internal partition frames are connected to the inner wall of the fuel tank barrel by riveting cover sealing; the mouth cover is arranged at the front end of the multiple sections of fuel tank barrel; the rear end of the multiple sections of fuel tank barrel is sealed by the end face sealing plate; the entire box body of the multiple sections of fuel tank barrel is also bonded with an outer skin.

5. The aircraft composite fuel tank according to claim 4, characterized in that: The multi-section oil tank barrel section includes oil tank section one, oil tank section two and oil tank section three; the oil tank section one has a closed front end face and an open rear end face; the front and rear end faces of the oil tank section two and oil tank section three are both open structures.

6. The aircraft composite fuel tank according to claim 4, characterized in that: The oil tank connecting frame is respectively sleeved with the front and rear oil tank barrel sections, and each oil tank barrel section is sleeved 20mm.

7. The aircraft composite fuel tank according to claim 6, characterized in that: The oil tank connection frame has an oil through hole at the bottom and an air vent at the top; and an oil tank connection plate is arranged on the oil tank connection frame.

8. The aircraft composite fuel tank according to claim 4, characterized in that: The internal bulkhead is a disconnected structure, which is connected by a bulkhead connecting plate; the top connecting gap of the internal bulkhead serves as a vent hole, and the bottom of the internal bulkhead is provided with an oil hole.

9. The aircraft composite fuel tank according to claim 4, characterized in that: The end face sealing plate is made of aluminum alloy, with a thickness of 2mm and a flange length of 40mm; the outer side surface and bottom surface of the end face sealing plate bonded to the outer skin are connected by countersunk rivets, and the inner side surface and top surface are connected by semi-circular head rivets.

10. The aircraft composite fuel tank according to claim 4, characterized in that: The outer side and the bottom of the multi-section oil tank barrel section are connected to the outer skin by countersunk rivets, and the inner side and the top are connected by semi-circular head rivets.

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