Aircraft engine truss type mounting bracket joint fireproof structure

Abstract

The invention belongs to the technical field of aviation fireproof structures, and discloses an aircraft engine truss type mounting bracket joint fireproof structure which comprises a fireproof cover, a corner connecting box, a backflow cover and a flexible connecting assembly. The fireproof cover covers a main body of an aircraft engine truss type mounting bracket joint, and the lower end of the fireproof cover is connected with the corner connecting box; the upper end of the fireproof cover is connected with a backflow cover, and a truss rod system of the truss type mounting bracket joint of the aircraft engine extends out of the backflow cover; and the flexible connecting assembly is fastened at the upper end of the fireproof cover and is filled in the reflux cover. Through split type fireproof cover design, a flexible connection mechanism and dynamic gap optimization, excellent fireproof isolation performance, excellent structural dynamic adaptability, high-temperature sealing performance, material compatibility and the like are achieved.

Description

Technical Field

[0001] This invention belongs to the field of aviation fireproof structure technology, and relates to a joint fireproof structure design that takes into account deformation coordination, specifically a fireproof structure for an aircraft engine truss mounting bracket joint. Background Technology

[0002] As a critical load-bearing structure connecting the engine to the airframe, the safety and reliability of the aircraft engine mounting bracket directly affect the overall operational performance and airworthiness of the aircraft. According to the Chinese Civil Aviation Regulations (CCAR) Clause 25.865, the design of the engine mounting area must ensure that, in the event of an engine fire or high-temperature gas leak, it can effectively isolate flames and high-temperature gases, preventing their propagation to adjacent airframe structures or fuel systems, and maintain structural integrity for a specified period to avoid catastrophic consequences. Furthermore, this clause sets forth clear requirements for the dynamic adaptability of fire-resistant structures, requiring them to maintain stable fire-resistant isolation functions even under complex conditions such as engine vibration, aerodynamic loads, and thermal deformation.

[0003] Traditional aircraft engine mount fireproof structures mostly adopt an integrated fireproof cover or a single heat insulation layer design. Although they can provide basic fireproof isolation, they have significant deficiencies in meeting the airworthiness requirements of CCAR25.865.

[0004] 1. Insufficient fire protection isolation timeliness and integrity: Due to the lack of segmented thermal expansion compensation design, integral fireproof covers are prone to local cracking or sealing failure due to thermal stress concentration in high-temperature environments, making it difficult to meet the fire resistance time specified in CCAR25.865, such as the 15-minute fire barrier requirement.

[0005] 2. Poor dynamic deformation adaptability: The existing fireproof cover and truss system have insufficient precision in gap control. Under engine vibration or aerodynamic load, friction or collision may occur, resulting in structural damage and potentially causing the fire barrier to fail, which violates the requirements of CCAR25.865 for the stability of fireproof structures.

[0006] 3. Limitations of materials and connection methods: Some designs use flexible materials to alleviate deformation problems, but their high temperature resistance, such as long-term resistance to temperatures above 800°C, is insufficient, or the connection interfaces, such as bolt fixation, lack thermal deformation compensation capabilities, resulting in degraded sealing performance under high temperature conditions and failure to pass airworthiness and fire resistance tests.

[0007] The above problems indicate that existing technologies are unable to meet the comprehensive requirements of CCAR25.865 for fire isolation effectiveness, structural dynamic adaptability, and long-term fire resistance stability. Summary of the Invention

[0008] To address the aforementioned issues, this invention provides a fireproof structure for an aircraft engine truss-type mounting bracket joint. Through modular design, flexible connection mechanisms, and gap optimization, it effectively isolates flames and high-temperature gases in the event of engine fire or high-temperature gas leakage, meeting the 15-minute fire barrier requirement stipulated in CCAR25.865. It adapts to truss structure deformation caused by engine vibration, aerodynamic loads, and thermal deformation, avoiding structural interference or fatigue damage. Through high-temperature resistant composite materials and a split-type sealing design, it ensures structural integrity and sealing performance under long-term high-temperature conditions.

[0009] The technical solution of the present invention is as follows: A fireproof structure for an aircraft engine truss mounting bracket joint includes a fireproof cover, a corner connection box, a backflow shield, and a flexible connection assembly. The fireproof cover covers the main body of the aircraft engine truss mounting bracket joint. The lower end of the fireproof cover is connected to the corner connection box, and the upper end of the fireproof cover is connected to the backflow shield. The truss rods of the aircraft engine truss mounting bracket joint extend from the backflow shield. The flexible connection assembly is fastened to the upper end of the fireproof cover and filled inside the backflow shield.

[0010] Furthermore, the fireproof cover has a split structure, consisting of a left half and a right half, with a 1mm to 2mm gap at the joint between the left and right halves.

[0011] Furthermore, a dynamic gap of 5mm to 8mm is provided between the fireproof cover and the truss system, and a dynamic gap of 5mm to 8mm is provided between the counterflow cover and the fireproof cover.

[0012] Furthermore, the cover surfaces of the counterflow shield and the fireproof shield have an overlap area of ​​at least 20 mm in the axial direction of the truss system, and the fireproof shield covers the truss system with an axial coverage of at least 60 mm. A labyrinthine fireproof structure is formed between the counterflow shield, the fireproof shield, and the truss system.

[0013] Furthermore, a high-temperature resistant silicone rubber sealing strip is filled between the counterflow shield and the fireproof shield.

[0014] Furthermore, the counterflow shield is a split-and-joint structure. The front end of the counterflow shield is fixed to the truss system with bolts, and the rear end of the counterflow shield is snapped onto the outside of the fireproof shield.

[0015] Furthermore, the flexible connection assembly includes clamps, rubber components, and elastic gaskets. The clamps are fastened to the upper end of the fireproof cover, the rubber components are filled on the contact surface between the counterflow cover and the truss system, and the elastic gaskets are arranged at the bolted connections to absorb thermal deformation stress.

[0016] Furthermore, the same number of truss rods as the aircraft engine truss mounting bracket joint are provided with a counterflow cowling.

[0017] Technical effects: This invention achieves the following significant technical effects through a split-type fireproof cover design, a flexible connection mechanism, and dynamic gap optimization: 1. Excellent fireproof and fire-resistant performance: Employing a laminated structure of aerogel or ceramic matrix composite materials, combined with a split fireproof cover and a counterflow cover to form a "labyrinthine" fire barrier, it can effectively block the spread of flames and high-temperature gases. Tests have verified that under continuous burning conditions of 1100℃ flame for 15 minutes, the inner surface temperature of the fireproof cover remains below 600℃, with no cracking, deformation, or gas leakage, fully meeting the fire resistance timeliness and integrity requirements stipulated in CCAR25.865.

[0018] 2. Excellent structural dynamic adaptability: A controllable dynamic gap of 5mm~8mm is reserved between the fireproof cover and the truss system, and between the counterflow cover and the fireproof cover. An expansion gap of 1mm~2mm is set at the joint to effectively absorb the structural deformation caused by thermal deformation and mechanical load, avoid interference, friction or stress concentration, and significantly improve the durability and reliability of the structure under vibration, aerodynamic load and thermal cycling.

[0019] 3. High-temperature sealing performance and material compatibility: The fireproof cover adopts a high-temperature resistant composite material and metal sheet laminate structure, which has both high fire resistance and impact resistance of ≥1000℃; the space between the backflow cover and the fireproof cover is filled with a high-temperature resistant silicone rubber sealing strip to form an airtight redundant protection, ensuring good sealing performance even under extreme temperatures.

[0020] 4. Modular design and ease of maintenance: The modular structure allows for quick disassembly and replacement, while the clamp and bracket nut connection method facilitates on-site maintenance, significantly reducing maintenance time and costs, and improving aircraft availability and operational economy.

[0021] 5. Wide industrial applicability and airworthiness compliance: This structural design is not only suitable for civil aircraft engine mounting brackets, but can also be extended to fire protection in high-temperature and high-vibration environments such as military aircraft and hypersonic vehicles. It has good versatility and engineering promotion value, and has been verified by CCAR25.865 airworthiness clause, demonstrating high reliability and safety.

[0022] 6. Industrial applicability This invention can be widely applied to the fireproof design of engine mounting brackets for civil aviation, military aircraft, and hypersonic vehicles, and is especially suitable for high-temperature and high-vibration operating conditions that require meeting stringent airworthiness standards. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the fireproof cover structure of the present invention.

[0024] Figure 2 This is a schematic diagram of the movement gap of the present invention.

[0025] Figure 3 This is a schematic diagram of the "maze" fireproof structure.

[0026] Among them, 101-left half cover, 102-sealing baffle, 103-right half cover, 104-first clamp, 105-first counterflow cover, 106-first rubber component, 107-first truss strut, 108-second counterflow cover, 109-second rubber component, 110-second truss strut, 111-second clamp, 112-truss joint, 113-connecting corner box. Detailed Implementation

[0027] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific design details are set forth in the following detailed description to provide a more complete understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setup and method set forth below, but covers any improvements, substitutions, and modifications to the structures, methods, and devices without departing from the spirit of the invention. In the drawings and the following description, any parts not exhaustively described are considered to be common knowledge or conventional practices in the art.

[0028] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0029] Example 1: A fireproof structure for an aircraft engine truss mounting bracket joint includes a fireproof cover, an angle connection box 113, a backflow shield, and a flexible connection assembly. The fireproof cover covers the main body of the aircraft engine truss mounting bracket joint. The lower end of the fireproof cover is connected to the angle connection box 113, and the upper end of the fireproof cover is connected to the backflow shield. The truss rods of the aircraft engine truss mounting bracket joint extend from the backflow shield. The flexible connection assembly is fastened to the upper end of the fireproof cover and filled inside the backflow shield.

[0030] The fireproof cover has a split structure, consisting of a left half cover 101 and a right half cover 103. A gap of 1mm to 2mm is provided at the joint between the left half cover 101 and the right half cover 103.

[0031] A dynamic gap of 5mm to 8mm is provided between the fireproof cover and the truss system, and a dynamic gap of 5mm to 8mm is provided between the counterflow cover and the fireproof cover.

[0032] The cover surfaces of the counterflow shield and the fireproof shield have an overlap area of ​​at least 20 mm in the axial direction of the truss system, and the fireproof shield covers the truss system with an axial coverage of at least 60 mm. The counterflow shield, the fireproof shield and the truss system form a labyrinthine fireproof structure.

[0033] A high-temperature resistant silicone rubber sealing strip is filled between the counterflow shield and the fireproof shield.

[0034] The counterflow shield is a split-and-joint structure. The front end of the counterflow shield is fixed to the truss system with bolts, and the rear end of the counterflow shield is snapped onto the outside of the fireproof shield.

[0035] The flexible connection assembly includes clamps, rubber parts, and elastic gaskets. The clamps are fastened to the upper end of the fireproof cover, the rubber parts are filled on the contact surface between the counterflow cover and the truss system, and the elastic gaskets are arranged at the bolted connection to absorb thermal deformation stress.

[0036] The same number of truss rods as the aircraft engine truss mounting bracket joint are provided with the same number of anti-flow cowlings.

[0037] Example 2: The core of this invention lies in the following split-type fireproof structure and its assembly method: Fireproof cover: It adopts a split design to cover the main body of the engine mounting bracket. The material is a laminated structure of aerogel or ceramic matrix composite material and stainless steel or high temperature alloy, and can withstand temperatures ≥1000℃. Connecting corner box 113: It is fixed to the base of the truss joint 112 by high-strength bolts, providing rigid support for the lower end of the fireproof cover; Counterflow shield: a split-and-joint structure, fixed to the truss system with bolts, and snapped onto the outside of the fireproof shield to form double protection; Flexible connection components include clamps and rubber parts. The clamps are used to fasten the upper end of the fireproof cover, the rubber parts are filled in the contact surface between the counterflow cover and the truss system, and the elastic gaskets are arranged at the bolt connections to absorb thermal deformation stress.

[0038] Split-type fireproof cover and gap optimization: The fireproof cover is divided into a left half and a right half, with a 1-2mm expansion gap reserved at the joint; A 5mm~8mm dynamic gap X1 is reserved between the fireproof cover and the truss system, and a 5mm~8mm isolation gap X2 is reserved between the counterflow cover and the fireproof cover to ensure no contact interference during deformation under load. See Figure 2 .

[0039] Double-layer protection design of the anti-airflow shield: The counterflow shield and the fireproof shield have an overlap area of ​​more than 20mm x3, and the fireproof shield and the rod system cover length x4 is greater than 60mm, forming a "maze-like" fireproof structure that effectively blocks flames from entering the interior area of ​​the fireproof shield.

[0040] A high-temperature resistant silicone rubber sealing strip is filled between the counterflow shield and the fireproof shield to achieve redundant airtight protection.

[0041] The assembly process for fire-resistant structures is as follows: Step 1: Fix the connecting corner box 113 to the connector base with high-strength bolts. The installation accuracy requirement is ±0.2mm. Step 2: Pre-fix the lower end of one side of the fireproof cover to the connecting corner box 113 using bolts / plate nuts; Step 3: Install the other side of the fireproof cover, and use clamps to lock the upper end. The clamps are connected by bolts / plate nuts. Step 4: Install the backflow shield on the truss system and secure it with bolts / plate nuts, ensuring that the backflow shield covers the outside of the fireproof shield upside down, and fill the gaps in the backflow shield with silicone rubber sealing strips.

[0042] The fire resistance performance was verified as follows: Fire resistance testing was conducted according to CCAR25.865 requirements: Test conditions: The outer surface of the fireproof cover was continuously burned by a flame at 1100℃ for 15 minutes; Results: The inner surface temperature of the fireproof cover was ≤600℃, with no cracks, deformations or gas leaks. Conclusion: The fire isolation timeliness and integrity requirements stipulated in the airworthiness regulations are met.

[0043] The present invention proposes a split-type fireproof structure that meets airworthiness standards through the following design innovations: Modular fireproof cover and flexible connection: The fireproof cover adopts a split-and-joint design, combined with rubber parts and clamps for flexible connection, so as to realize the adaptive adjustment of thermal expansion, avoid stress concentration, and ensure the sealing integrity at high temperature.

[0044] Dynamic gap optimization design: Controllable gaps are reserved between the fireproof cover and the truss system and the reverse flow cover. Combined with the "reverse buckle" structure design of the reverse flow cover, it still maintains interference-free movement under thermal deformation or mechanical load, which meets the requirements of CCAR25.865 for the deformation resistance of fireproof structures.

[0045] Application of high-temperature resistant composite materials: The fireproof cover adopts an aerogel or ceramic matrix composite material CMC and metal laminate structure, which has both high fire resistance (withstanding temperatures above 1000℃) and impact resistance. Its isolation effectiveness has been verified by the combustion test for airworthiness certification.

[0046] Through the above-mentioned technical solution, this invention not only solves the inherent defects of traditional fireproof structures, but also ensures compliance with the stringent airworthiness requirements of CCAR25.865 from the design source, providing a reliable guarantee for the fire safety of engine mounting brackets.

[0047] Example 3: A fireproof structure for an aircraft engine truss-type mounting bracket joint includes a left half-cover 101 and a right half-cover 103 of a fireproof cover, a connecting corner box, a deflector, clamps, rubber components, etc. The fireproof cover is split in half and fits together to cover the main body of the engine nose. The lower end of the fireproof cover is fixed to the connecting corner box by bolts, and the upper end is tightened by clamps. The deflector is split in half and fits together to press the rubber components, and is fixed to the truss system by bolts, and is snapped onto the outside of the fireproof cover.

[0048] The main material consists of a 0.1mm thick high-temperature alloy or stainless steel sheet covered with aerogel, or ceramic matrix composite material, etc., with a thickness of 5mm~10mm.

[0049] The outer contour of the fireproof cover can be customized by mold according to the surrounding components. The fireproof cover is divided into two halves, with the seam covered by a high-temperature alloy or stainless steel sheet, and a specific gap is reserved between the fireproof cover and the truss members.

[0050] The connecting corner box is made of titanium alloy or stainless steel with a wall thickness of 2mm~3mm and is fixed by bolts to the truss joint base.

[0051] A support plate nut is installed on the connecting corner box, and bolts are used to support the installation of the fireproof cover.

[0052] The material of the counterflow hood is titanium alloy or stainless steel, with a wall thickness of 2mm to 3mm. A specific gap is reserved between the inner wall of the counterflow hood and the fireproof hood, and the length of the overlap area between the counterflow hood and the fireproof hood is not less than 12mm.

[0053] The raw material for the rubber parts is fire-retardant rubber, with embedded rubber fabric and external fabric covering, and the cross-sectional shape is grooved.

[0054] The clamps are made of stainless steel or titanium alloy thin plates, 1mm to 2mm thick, and are connected with bolts, support plates and nuts to tighten the fireproof cover.

[0055] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements without departing from the principle of the present invention, and these improvements should also be considered within the scope of protection of the present invention.

Claims

1. A fireproof structure for a truss-type mounting bracket joint for an aircraft engine, characterized in that, It includes a fireproof cover, an angle connection box (113), a counterflow cover, and a flexible connection assembly. The fireproof cover covers the main body of the aircraft engine truss mounting bracket joint. The lower end of the fireproof cover is connected to the angle connection box (113), and the upper end of the fireproof cover is connected to the counterflow cover. The truss rods of the aircraft engine truss mounting bracket joint extend out from the counterflow cover. The flexible connection assembly is fastened to the upper end of the fireproof cover and filled inside the counterflow cover.

2. The fireproof structure for an aircraft engine truss-type mounting bracket joint according to claim 1, characterized in that, The fireproof cover has a split structure, consisting of a left half cover (101) and a right half cover (103), with a gap of 1mm to 2mm at the joint between the left half cover (101) and the right half cover (103).

3. The fireproof structure for an aircraft engine truss-type mounting bracket joint according to claim 2, characterized in that, A dynamic gap of 5mm to 8mm is provided between the fireproof cover and the truss system, and a dynamic gap of 5mm to 8mm is provided between the counterflow cover and the fireproof cover.

4. The fireproof structure for the truss-type mounting bracket joint of an aircraft engine according to claim 3, characterized in that, The cover surfaces of the counterflow shield and the fireproof shield have an overlap area of ​​at least 20 mm in the axial direction of the truss system, and the fireproof shield covers the truss system with an axial coverage of at least 60 mm. The counterflow shield, the fireproof shield and the truss system form a labyrinthine fireproof structure.

5. The fireproof structure for an aircraft engine truss-type mounting bracket joint according to claim 3, characterized in that, A high-temperature resistant silicone rubber sealing strip is filled between the counterflow shield and the fireproof shield.

6. The fireproof structure for an aircraft engine truss-type mounting bracket joint according to claim 1, characterized in that, The counterflow shield is a split-and-joint structure. The front end of the counterflow shield is fixed to the truss system with bolts, and the rear end of the counterflow shield is snapped onto the outside of the fireproof shield.

7. The fireproof structure for an aircraft engine truss-type mounting bracket joint according to claim 1, characterized in that, The flexible connection assembly includes clamps, rubber parts, and elastic gaskets. The clamps are fastened to the upper end of the fireproof cover, the rubber parts are filled on the contact surface between the counterflow cover and the truss system, and the elastic gaskets are arranged at the bolted connection to absorb thermal deformation stress.

8. The fireproof structure for an aircraft engine truss-type mounting bracket joint according to claim 1, characterized in that, The same number of truss rods as the aircraft engine truss mounting bracket joint are provided with the same number of anti-flow cowlings.

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