Plastic caps filled with sealing compound as combined protection against fuel and hydraulic fluid and against lightning strikes
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Solution Overview
Problem
The existing methods for sealing connecting elements in aircraft construction, particularly rivets and screw connections, are economically inefficient and complex due to the need for specialized sealing compound-filled plastic caps that provide protection against fuel, hydraulic oil, and lightning strikes, with limited variability and high manual labor requirements.
Innovation Solution
Development of plastic caps made from high-performance polymers with a sealing compound containing gas- and/or air-filled hollow packings, which are cohesively bonded and filled with a polysulfide-based sealing compound, offering enhanced energy absorption and breakdown resistance, allowing for automated application and reduced manual effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If seal caps with twin-shell construction and integrated air gap are used for protection against lightning strikes, then protection against lightning strikes is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines multiple protective functions (sealing against fuel/hydraulic oil and protection against lightning strikes) into a single integrated plastic cap structure. The cap includes an integrated air gap that serves as a lightning protection element while the entire structure provides sealing, eliminating the need for separate seal caps and reducing construction complexity.
Solution Approach 2:
The plastic cap is designed to perform multiple functions simultaneously: it seals connecting elements against fuel and hydraulic oil while the integrated air gap provides lightning strike protection. This multi-functional design reduces the number of separate components needed and simplifies the overall construction.
2Reliability
If seal caps with twin-shell construction are used for lightning protection, then protection against lightning strikes is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent merges the sealing function and lightning protection function into a single molded plastic cap structure. The cap is produced as one piece with an integrated air gap, eliminating the need for separate manufacturing and assembly steps for multiple components, thereby improving ease of manufacture.
Solution Approach 2:
The patent changes the material composition of the cap by incorporating filling compounds (such as metal powders or conductive materials) into the plastic matrix. This modification provides lightning protection through the material itself rather than requiring complex structural features, simplifying manufacturing.
3Reliability
If surface painting is applied to assure good adhesion of sealing compound, then adhesion of sealing compound is improved, but device complexity and production steps increase
Solution Approach 1:
The patent modifies the surface properties of the plastic cap through material selection and surface treatment during the molding process. The cap material is formulated to provide inherent adhesion properties, or surface treatments are applied during molding, eliminating the need for separate painting steps while ensuring good adhesion of the sealing compound.
Solution Approach 2:
The patent prepares the surface of the cap with adhesion-promoting features during the molding process itself. Surface treatments, textures, or chemical modifications are applied in advance during cap production, so that when the sealing compound is applied later, good adhesion is achieved without requiring intermediate painting steps.
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 enables a broader spectrum of use for sealing compound-filled plastic caps, increasing their frequency of application in aircraft construction by providing effective protection against fuel, hydraulic oil, and lightning strikes while reducing production and assembly costs and manual labor, thus enhancing economic viability and variability.
Implementation Method 1
a sealing compound having a high energy absorption capacity and including at least one filler selected from the group consisting of gas- and/or air-filled hollow packings
Implementation Method 2
has a breakdown resistance of at least 10 kV/mm to DIN IEC 60243
Implementation Method 3
The plastic cap and the sealing compound here have been cohesively bonded to one another
Data Source
AI summary
Provided herein are sealing compound-filled plastic caps for sealing of connecting elements in aircraft construction against liquids, wherein these plastic caps function as combined protection against fuel and hydraulic oil, especially that based on tributyl phosphate, and against lightning strikes, and can be produced and applied in an economically viable manner. The plastic cap for sealing of connecting elements in aircraft construction consists predominantly of at least one high-performance polymer having a breakdown resistance of at least 10 kV/mm to DIN IEC 60243, and has been filled with a sealing compound having a high energy absorption capacity and including at least one filler selected from the group consisting of gas- and/or air-filled hollow packings, where the plastic cap and the sealing compound are cohesively bonded to one another. Additionally provided is a method of filling and application of such plastic caps, and a corresponding aircraft.