Aircraft Transparency Pressure Seal with Integrated Compression Stops
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Solution Overview
Problem
Aircraft transparencies face challenges with pressure seal integrity due to torque loss and creep, as well as precipitation static, which can lead to moisture penetration, pressure loss, and electrical interference.
Innovation Solution
An aircraft transparency assembly with a pressure seal incorporating integrated compression stops and an anti-static drain assembly, featuring a flexible conductive element connecting the transparency to the aircraft fuselage, helps maintain seal integrity and drain electrical charges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If torque is applied to bolts to compress the pressure seal, then seal integrity is improved, but torque loss and creep occur over time reducing the seal effectiveness
Solution Approach 1:
The pressure seal is segmented into distinct functional zones: a compression zone with integrated compression stops that maintains constant compressive force on the seal, and a deflection zone that allows controlled movement. This segmentation enables the seal to maintain integrity without requiring constant high torque on the bolts, preventing torque loss and creep over time.
Solution Approach 2:
The compression stops are designed to maintain a constant compression parameter on the pressure seal regardless of bolt deflection or torque variations. By changing the parameter from variable compression (dependent on bolt torque) to constant compression (maintained by the stops), the system achieves reliable seal integrity over extended periods without torque retention issues.
2Reliability
If the pressure seal is highly compressed to ensure sealing, then moisture penetration is prevented, but the pressure seal loses flexibility and cannot accommodate fuselage expansion and contraction
Solution Approach 1:
The pressure seal structure is divided into a compression region with integrated stops that provide constant sealing force, and a flexible region that can deform to accommodate fuselage dimensional changes. This segmentation allows the seal to simultaneously maintain moisture protection through constant compression while preserving adaptability through the flexible portion that moves with fuselage expansion and contraction.
Solution Approach 2:
The pressure seal is designed with dynamic characteristics, allowing it to transition between compressed and relaxed states as the fuselage expands and contracts. The integrated compression stops provide a dynamic equilibrium point, maintaining adequate compression for moisture protection while permitting the necessary movement for adaptability during flight operations.
3Adaptability or versatility
If the pressure seal material is made flexible to accommodate fuselage movement, then adaptability is improved, but the material loses compression force over time leading to creep and seal failure
Solution Approach 1:
The seal system is segmented such that the flexible pressure seal material provides adaptability for fuselage movement, while separate integrated compression stops provide constant compressive force. This segmentation allows the flexible material to maintain its range of motion without suffering from compression force loss, as the compression stops continuously replenish the compression force regardless of material relaxation or creep.
4Device complexity
If conventional pressure seals are used without integrated compression stops, then device complexity is reduced, but torque loss and creep lead to loss of seal integrity over time
Solution Approach 1:
The compression stop functionality is merged directly into the pressure seal body as an integrated feature rather than a separate component. This merging maintains relatively simple device complexity while achieving reliable long-term seal integrity through constant compression force, eliminating the need for separate adjustment mechanisms or complex bolt torque control systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances torque retention and prevents creep, while effectively draining precipitation static, reducing moisture and electrical interference issues.
Implementation Method 1
an anti-static drain assembly comprising at least one flexible conductive element having a first end in electrical contact with the outer surface of the ply and a second end in electrical contact with the conductive tab
Implementation Method 2
a flexible gasket or 'pressure seal' is positioned between the transparency and the aircraft fuselage. When the transparency is attached to the fuselage, typically by bolts, the pressure seal is compressed between the outer edge of the transparency and the fuselage
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
An aircraft transparency assembly includes an aircraft transparency (48) having at least one ply having an outer surface and an extended portion (60) . The assembly also includes a pressure seal (10) configured to engage the extended portion of the ply, wherein the pressure seal includes a pressure seal body, at least one integrated compression stop (36) and at least one conductive tab (30). The transparency can include an optional anti-static drain assembly (66) including at least one flexible conductive element having a first end in electrical contact with the outer surface of the ply, for example with an optional conductive coating (58) on the outer surface of the ply, and a second end configured to contact the pressure seal.