Composite fuel tank, assembly jig and method of assembly thereof

Abstract

This invention discloses a composite fuel tank, assembly fixture, and assembly method thereof, relating to the field of integrated fuel tank assembly technology. It includes a mounting frame, on the top of which a main reducer is mounted; the mounting frame is sealed with sealant; and a fuel tank is fixedly installed inside the mounting frame. This invention positions the mounting platform and assembles it with a first side frame, a second side frame, and a skin using adhesive riveting to form an integral structural outer wall. This strengthens the overall integrity and rigidity of the fuel tank while reducing the weight of the fuselage. This invention effectively ensures the load-bearing capacity of the overall fuel tank structure, with a simple assembly process, high efficiency, fewer assembly fixtures, and low manufacturing cost.

Description

Technical Field

[0001] This invention relates to the field of integrated fuel tank assembly technology, and in particular to a composite fuel tank, assembly fixture and assembly method thereof. Background Technology

[0002] Most military aircraft, civilian aircraft, and drones now rely on aviation kerosene, gasoline, diesel, etc. to power their engines. Therefore, fuel tanks need to be installed in the airframe to store fuel. The combustion of fuel in the engine powers the propeller blades and other components, giving the aircraft lift and keeping it in flight.

[0003] Modern aircraft typically house fuel tanks in the fuselage and wing box sections. Some aircraft also utilize independent flexible fuel tanks within the structure. Previously, fuel tanks were individually designed structural components, sealed together using rivets to ensure airtightness, safety, and reliability. Designing independent fuel tank components would inevitably increase the aircraft's structural weight and shorten its range, contradicting the current pursuit of lightweight design and long endurance.

[0004] Currently, most structurally integrated composite fuel tanks are designed as separate, independent units. The main reduction platform is installed separately from the fuel tank and structural skin, and the fuel tank components cannot become part of the structural load-bearing structure. The disadvantages of this approach are complex structure, cumbersome assembly process, numerous assembly jigs, long operation time, and low degree of fuel tank integration.

[0005] Therefore, there is an urgent need to invent a composite fuel tank, an assembly fixture, and an assembly method thereof. Summary of the Invention

[0006] The purpose of this invention is to provide a composite fuel tank, assembly fixture, and assembly method thereof to solve the problems existing in the prior art. It can realize the installation of the main reducer or engine, while the fuel tank can bear the load as a body structure; the riveting assembly can also meet the fuel tank sealing requirements, and the assembly fixture can be used to pass the fuel tank air tightness and fuel tank oil tightness tests; the number of assembly fixtures is reduced, and the manufacturing cost is reduced.

[0007] To achieve the above objectives, the present invention provides the following solution: The present invention provides a composite fuel tank, comprising:

[0008] The mounting frame has a main reducer mounted on its top; the mounting frame is sealed with sealant.

[0009] A fuel tank is fixedly installed inside the mounting frame.

[0010] The mounting frame includes: a mounting platform for mounting the main reducer;

[0011] The first and second side frames have the same structure; the first and second side frames are riveted to both ends of the bottom surface of the mounting platform.

[0012] The skin consists of two pieces, which are respectively riveted to the two ends of the bottom surface of the mounting platform; each skin is fixedly connected to the first side frame and the second side frame at both ends;

[0013] Both of the aforementioned skins have annular limiting protrusions formed on them, and the two ends of the fuel tank are respectively placed inside the two annular limiting protrusions.

[0014] An assembly fixture, comprising:

[0015] Assemble the frame;

[0016] The clamp assembly is fixedly installed inside the assembly frame;

[0017] The composite oil tank, wherein the mounting frame is fixed within the clamp assembly.

[0018] The clamp assembly includes a positioning part and a limiting part;

[0019] The positioning part includes a mounting platform connector, which is fixedly installed in the middle of the top surface of the assembly frame; the bottom of the mounting platform connector is fixedly connected to the top of the mounting platform through a first positioning pin.

[0020] The first side connector and the second side connector are respectively fixedly installed at both ends of the top surface of the assembly frame and are arranged parallel to the mounting platform connector; the bottom of the first side connector and the second side connector are both fixedly installed with an in-frame locator and a skin positioning ear piece; the in-frame locator is assembled and connected to the top inner frame of the first side frame or the second side frame.

[0021] The first and second side frames are connected to the top of the skin via skin positioning earpieces;

[0022] The limiting part includes a frame limiting plate, a fuel tank side limiting plate, and a fuel tank bottom limiting plate; two sets of frame limiting plates are provided, which are respectively fixedly installed on two opposite side walls of the assembly frame, and the frame limiting plates abut against the two skins respectively; the fuel tank side limiting plate and the fuel tank bottom limiting plate are both fixedly installed at the center of the bottom surface of the assembly frame, the fuel tank side limiting plate abuts against both sides of the fuel tank; the fuel tank bottom limiting plate abuts against the bottom of the fuel tank.

[0023] The frame locator and skin positioning earpiece are also installed at the bottom of the assembly frame; the frame locator is assembled and connected to the bottom inner frame of the first side frame or the second side frame; the first side frame and the second side frame are connected to the bottom of the skin through the skin positioning earpiece.

[0024] The bottom of the assembly frame is also equipped with a frame bottom locator and a frame top locator; the bottom and top surfaces of the first and second side frames are respectively fixedly connected to the frame bottom locator and the frame top locator.

[0025] A fuel tank positioning lug is also fixedly installed on the bottom limit plate of the fuel tank; the fuel tank positioning lug is fixedly connected to the bottom surface of the fuel tank.

[0026] An assembly method for mounting an assembly fixture includes the following steps:

[0027] Determine the mounting platform positioning and installation on the mounting platform connector;

[0028] The first side frame, the second side frame, the two skins, and the fuel tank are positioned and installed below the mounting platform.

[0029] Make sure to apply sealant to the joints between the mounting platform, the first side frame, the second side frame, the two skins, and the fuel tank;

[0030] Determine the riveting and forming process of the composite fuel tank;

[0031] The composite fuel tank is pressure tested under the limiting conditions of the skeleton limiting plate, the fuel tank side limiting plate and the fuel tank bottom limiting plate.

[0032] The pressure test is to test the airtightness of the mounting frame and the airtightness and oil tightness of the fuel tank.

[0033] The present invention discloses the following technical effects: After the installation platform is positioned, it is assembled with the first side frame, the second side frame and the skin by gluing and riveting to form an integral outer wall structure. Through this assembly technology, on the one hand, the integrity and rigidity of the fuel tank can be strengthened; on the other hand, the weight of the fuselage can be reduced, and the number of assembly tools can be reduced.

[0034] In the assembly technology of this invention, the side wall and bottom plate of the fuel tank are positioned by a clamping assembly, which can ensure that the gap between the inner wall of the fuel tank and the skin is uniform, avoiding the problems of pressure drop and oil leakage during sealing and riveting caused by single-sided gaps in traditional positioning methods.

[0035] This invention can effectively ensure the load-bearing capacity of the overall structure of the fuel tank, with simple assembly process, high efficiency, few assembly fixtures, and low manufacturing cost. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0038] Figure 2 This is a schematic diagram of the composite fuel tank structure of the present invention;

[0039] Figure 3 This is a schematic diagram of the fixture assembly structure of the present invention;

[0040] Figure 4 This is a schematic diagram of the top mounting structure of the composite fuel tank of the present invention;

[0041] Figure 5 This is a schematic diagram of the fuel tank bottom limiting plate structure of the present invention;

[0042] Figure 6 This is a schematic diagram of the fuel tank side limiting plate structure of the present invention;

[0043] The components include: 1. Mounting platform; 2. First side frame; 3. Second side frame; 4. Skin; 5. Fuel tank; 6. Assembly frame; 7. Frame limiting plate; 8. Fuel tank side limiting plate; 9. Fuel tank bottom limiting plate; 11. Mounting platform connector; 12. First side connector; 13. Frame internal locator; 14. Skin positioning lug; 15. Frame bottom locator; 16. Frame top locator; 17. Fuel tank positioning lug; 18. First positioning pin; 19. Second side connector. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] This invention provides a composite fuel tank, comprising:

[0047] The mounting frame is equipped with a main reducer mounted on top; the mounting frame is sealed with sealant.

[0048] The fuel tank 5 is fixedly installed inside the mounting frame.

[0049] The mounting frame includes: mounting platform 1, used for mounting the main reducer;

[0050] The first side frame 2 and the second side frame 3 have the same structure; the first side frame 2 and the second side frame 3 are riveted to both ends of the bottom surface of the mounting platform 1;

[0051] Two skin panels 4 are provided and are respectively riveted to the two ends of the bottom surface of the mounting platform 1; each skin panel 4 is fixedly connected to the first side frame 2 and the second side frame 3 at both ends respectively.

[0052] Both skins 4 have annular limiting protrusions, and the two ends of the fuel tank 5 are respectively placed inside the two annular limiting protrusions.

[0053] An assembly fixture, comprising:

[0054] Assemble frame 6;

[0055] The clamping assembly is fixedly installed inside the assembly frame 6;

[0056] The composite fuel tank is mounted on a frame that is fixed within the clamping assembly.

[0057] The clamp assembly includes a positioning part and a limiting part;

[0058] The positioning part includes a mounting platform connector 11, which is fixedly installed in the middle of the top surface of the assembly frame 6; the bottom of the mounting platform connector 11 is fixedly connected to the top of the mounting platform 1 through a first positioning pin 18;

[0059] The first side connector 12 and the second side connector 19 are respectively fixedly installed at both ends of the top surface of the assembly frame 6 and are arranged parallel to the mounting platform connector 11; the bottom of the first side connector 12 and the second side connector 19 are both fixedly installed with the frame locator 13 and the skin positioning ear piece 14; the frame locator 13 is assembled and connected to the top inner frame of the first side frame 2 or the second side frame 3.

[0060] The first side frame 2 and the second side frame 3 are connected to the top of the skin 4 via the skin positioning earpiece 14;

[0061] The limiting part includes a frame limiting plate 7, a fuel tank side limiting plate 8, and a fuel tank bottom limiting plate 9; two sets of frame limiting plates 7 are provided, which are fixedly installed on the two opposite side walls of the assembly frame 6, and the frame limiting plates 7 abut against the two skins 4 respectively; the fuel tank side limiting plate 8 and the fuel tank bottom limiting plate 9 are both fixedly installed at the center of the bottom surface of the assembly frame 6, the fuel tank side limiting plate 8 abuts against the two sides of the fuel tank 5; the fuel tank bottom limiting plate 9 abuts against the bottom of the fuel tank 5.

[0062] The bottom of the assembly frame 6 is also equipped with an in-frame locator 13 and a skin positioning ear piece 14; the in-frame locator 13 is assembled and connected to the bottom inner frame of the first side frame 2 or the second side frame 3; the first side frame 2 and the second side frame 3 are connected to the bottom of the skin 4 through the skin positioning ear piece 14.

[0063] The bottom of the assembly frame 6 is also equipped with a frame bottom locator 15 and a frame top locator 16; the bottom and top surfaces of the first side frame 2 and the second side frame 3 are respectively fixedly connected to a frame bottom locator 15 and a frame top locator 16.

[0064] A fuel tank positioning ear piece 17 is also fixedly installed on the bottom limit plate 9 of the fuel tank; the fuel tank positioning ear piece 17 is fixedly connected to the bottom surface of the fuel tank 5.

[0065] An assembly method for mounting an assembly fixture includes the following steps:

[0066] Ensure that the mounting platform 1 is positioned and installed on the mounting platform connector 11;

[0067] Determine the positioning and installation of the first side frame 2, the second side frame 3, the two skins 4, and the fuel tank 5 below the mounting platform 1;

[0068] Make sure to apply the sealant to the joint between the mounting platform 1, the first side frame 2, the second side frame 3, the two skins 4, and the fuel tank 5;

[0069] Determine the riveting and forming process of the composite fuel tank;

[0070] The composite fuel tank is pressure tested under the limiting conditions of the skeleton limiting plate 7, the fuel tank side limiting plate 8, and the fuel tank bottom limiting plate 9.

[0071] The pressure test was conducted to test the airtightness of the mounting frame and the airtightness and oil tightness of the fuel tank 5.

[0072] In one embodiment of the present invention, the mounting platform 1 is connected and pressed onto the mounting platform connector 11 by the first positioning pin 18 to ensure the positional accuracy and flatness of the mounting platform 1.

[0073] Furthermore, there are four first locating pins 18, each with a unit diameter of 20mm.

[0074] In one embodiment of the present invention, the first side frame 2 and the second side frame 3 are positioned and installed at the bottom end of the mounting platform 1 by means of a second positioning pin;

[0075] Furthermore, a second locating pin is provided, with a unit diameter of 10mm.

[0076] In one embodiment of the present invention, the bottom of the fuel tank 5 is positioned within the clamping assembly by two fuel tank bottom limiting plates 9, ensuring the relative position of the bottom of the fuel tank 5 in space.

[0077] In one embodiment of the present invention, each of the two fuel tank bottom limiting plates 9 is equipped with a fuel tank positioning lug 17, which is positioned by inserting two positioning pins with a diameter of 4.5mm into the fuel tank positioning lug 17; this ensures the relative position of the fuel tank 5's inner wall within the space. Simultaneously, the fuel tank bottom limiting plates 9 can limit the deformation of the inner wall of the fuel tank 5 during airtight and oil tightness pressurization (0.18MPa).

[0078] In one embodiment of the present invention, the skin 4 is positioned on the assembly fixture by inserting two 4.5mm diameter locating pins into the skin positioning earpiece 14 and the frame limiting plate 7. The relative positions of the two skins with the first side frame 2, the second side frame 3, the mounting platform 1, and the inner wall of the fuel tank 5 are also determined. Simultaneously, the frame limiting plate 7 ensures that the deformation of the left and right skins is limited during airtightness and fuel tightness pressurization.

[0079] In one embodiment of the present invention, after the mounting frame is positioned by the tooling positioning component, the drill bit is clamped by a hand-held pneumatic drill to drill initial holes and enlarge final holes between the various parts.

[0080] Furthermore, after the connecting holes between parts are drilled, the parts are disassembled and the burrs inside the holes are removed.

[0081] Furthermore, after removing burrs from the connecting holes of the parts, the bonding surfaces are sanded with sealant (HM109-1 and primer NJD-3); 240 grit sandpaper is selected for sanding.

[0082] Furthermore, after the adhesive surfaces of the parts are treated, they are cleaned and then adhesive is applied (NJD-3 primer, applied in 3 coats with 15-minute intervals between each coat, and HM109-1).

[0083] Furthermore, after the parts are reassembled and positioned, they are riveted together using standard connecting parts to form a composite oil tank.

[0084] In one embodiment of the present invention, the fuel tank 5 is pressurized (0.18MPa) by connecting to an external pressure tester through the filler cap; after fuel is added through the filler cap, the fuel tank is pressurized (0.18MPa) by connecting to an external pressure tester.

[0085] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0086] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A composite fuel tank, characterized in that, include: The mounting frame has a main reducer mounted on its top; the mounting frame is sealed with sealant. A fuel tank (5) is fixedly installed inside the mounting frame; The mounting frame includes: a mounting platform (1) for mounting the main reducer; The first side frame (2) and the second side frame (3) have the same structure; the first side frame (2) and the second side frame (3) are riveted to both ends of the bottom surface of the mounting platform (1); The skin (4) is provided in two pieces and is respectively riveted to the two ends of the bottom surface of the mounting platform (1); each of the skins (4) is fixedly connected to the first side frame (2) and the second side frame (3) at both ends respectively; Both of the skins (4) have annular limiting protrusions, and the two ends of the fuel tank (5) are respectively placed in the two annular limiting protrusions.

2. An assembly fixture, characterized in that, include: Assemble the frame (6); The clamp assembly is fixedly installed inside the assembly frame (6); The composite fuel tank according to claim 1, wherein the mounting frame is fixed inside the clamp assembly.

3. An assembly fixture according to claim 2, characterized in that: The clamp assembly includes a positioning part and a limiting part; The positioning part includes a mounting platform connector (11), which is fixedly installed in the middle of the top surface of the assembly frame (6); the bottom of the mounting platform connector (11) is fixedly connected to the top of the mounting platform (1) through a first positioning pin (18); The first side connector (12) and the second side connector (19) are respectively fixedly installed at both ends of the top surface of the assembly frame (6) and are arranged parallel to the mounting platform connector (11); the bottom of the first side connector (12) and the second side connector (19) are both fixedly installed with an in-frame locator (13) and a skin positioning ear piece (14); the in-frame locator (13) is assembled and connected to the top inner frame of the first side frame (2) or the second side frame (3); The first side frame (2) and the second side frame (3) are connected to the top of the skin (4) via a skin positioning earpiece (14); The limiting part includes a frame limiting plate (7), a fuel tank side limiting plate (8), and a fuel tank bottom limiting plate (9); the frame limiting plate (7) is provided in two sets, which are fixedly installed on the two opposite side walls of the assembly frame (6), and the frame limiting plate (7) abuts against the two skins (4); the fuel tank side limiting plate (8) and the fuel tank bottom limiting plate (9) are both fixedly installed at the center of the bottom surface of the assembly frame (6), the fuel tank side limiting plate (8) abuts against the two sides of the fuel tank (5); the fuel tank bottom limiting plate (9) abuts against the bottom of the fuel tank (5).

4. An assembly fixture according to claim 3, characterized in that: The frame locator (13) and the skin positioning earpiece (14) are also installed at the bottom of the assembly frame (6); the frame locator (13) is assembled and connected to the bottom inner frame of the first side frame (2) or the second side frame (3); the first side frame (2) and the second side frame (3) are connected to the bottom of the skin (4) through the skin positioning earpiece (14). The bottom of the assembly frame (6) is also equipped with a frame bottom locator (15) and a frame top locator (16); the bottom and top surfaces of the first side frame (2) and the second side frame (3) are respectively fixedly connected to the frame bottom locator (15) and the frame top locator (16).

5. An assembly fixture according to claim 3, characterized in that: A fuel tank positioning earpiece (17) is also fixedly installed on the bottom limiting plate (9) of the fuel tank; the fuel tank positioning earpiece (17) is fixedly connected to the bottom surface of the fuel tank (5).

6. A method for assembling an assembly fixture, characterized in that, The assembly fixture for installing any one of claims 2-5 comprises the following steps: Determine that the mounting platform (1) is positioned and installed on the mounting platform connector (11); Determine the positioning and installation of the first side frame (2), the second side frame (3), the two skins (4) and the fuel tank (5) below the mounting platform (1); Determine that the sealant will be bonded to the joint between the mounting platform (1), the first side frame (2), the second side frame (3), the two skins (4) and the fuel tank (5); Determine the riveting and forming process of the composite fuel tank; The composite fuel tank is pressure tested under the limiting conditions of the skeleton limiting plate (7), the fuel tank side limiting plate (8) and the fuel tank bottom limiting plate (9).

7. The assembly method of an assembly fixture according to claim 6, characterized in that: The pressure test is to test the airtightness of the mounting frame and the airtightness and oil tightness of the fuel tank (5).

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