Self-Sealing Liquid Bladders Using Expanded Teflon Particles
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Solution Overview
Problem
Conventional self-sealing fuel tanks are slow to seal punctures, inadequate for larger caliber penetrations, and are stiff, heavy, and difficult to install, making them inefficient for military and other applications where rapid and effective sealing of fuel leaks is critical.
Innovation Solution
The development of self-sealing liquid bladders with multiple layers, including a liquid impermeable material layer and a sealing layer with shape-changing structures, compressed materials, or segmented cellular structures that rapidly seal punctures by expanding to plug holes, providing enhanced flexibility, lighter weight, and easier installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional self-sealing bladders use natural rubber to seal punctures, then sealing function is provided, but sealing time is excessive (2 minutes or more)
Solution Approach 1:
The patent changes the physical and chemical parameters of the sealing material by using expanded Teflon FEP particles instead of natural rubber. These particles undergo rapid expansion when exposed to liquid fuel, changing from a compressed state to an expanded state that quickly seals punctures, reducing sealing time from 2+ minutes to a rapid response while maintaining reliable sealing function.
Solution Approach 2:
The patent uses Teflon FEP particles that are coated with a substance that causes them to expand when exposed to liquid fuel. This creates a copying effect where the particles replicate the sealing action of traditional rubber but through a different mechanism - the expansion of compressed particles rather than swelling of rubber, achieving rapid sealing without the time delay of conventional materials.
2Reliability
If conventional self-sealing bladders use natural rubber, then sealing capability is provided, but the bladder becomes stiff and heavy
Solution Approach 1:
The patent replaces thick natural rubber layers with a thin film containing compressed expanded Teflon FEP particles. This thin film structure maintains flexibility and significantly reduces weight compared to conventional thick rubber bladders, while the particles provide the necessary sealing capability when activated by liquid fuel exposure.
Solution Approach 2:
The patent changes the material parameters from dense natural rubber to compressed expanded Teflon FEP particles. This parameter change allows the bladder to achieve sealing capability with much lower density and weight, while the compressed state of the particles before activation maintains a thin, flexible profile that does not add significant mass.
3Reliability
If conventional self-sealing bladders use natural rubber, then sealing function is achieved, but the bladder becomes difficult and expensive to install
Solution Approach 1:
The patent uses a thin film containing compressed Teflon FEP particles that is easier to handle and install than thick natural rubber bladders. The thin film profile allows for simpler installation procedures, reduced handling difficulty, and lower installation costs while maintaining the essential sealing function through the expanded particles upon activation.
4Reliability
If conventional self-sealing bladders are designed for sealing, then puncture sealing is provided, but they cannot effectively seal larger caliber penetrations
Solution Approach 1:
The patent segments the sealing function into multiple compressed expanded Teflon FEP particles distributed throughout the thin film. When a puncture or penetration of any size occurs, multiple particles are exposed to liquid fuel and expand to collectively seal the opening. This segmented approach allows the system to adapt to various penetration sizes, from small punctures to larger caliber penetrations, by activating an appropriate number of particles.
5Reliability
If the bladder wall is made thick with natural rubber for self-sealing, then sealing function is improved, but flexibility and ease of installation are reduced
Solution Approach 1:
The patent replaces thick natural rubber with a thin film containing compressed Teflon FEP particles. This thin film structure inherently provides superior flexibility and conformability while the compressed particles remain dormant until needed. When activated, the particles expand within the flexible film to provide self-sealing without compromising the flexible shape and ease of installation.
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 self-sealing bladders achieve rapid and effective sealing of punctures, including larger wounds, with reduced weight and installation complexity, minimizing fuel loss and environmental risk in military and other applications.
Implementation Method 1
the sealing layer includes a plurality of shape changing structures that change geometry when exposed to the liquid in the bladder
Implementation Method 2
the sealing layer includes at least one compressed material that is retained in the sealing layer in a compressed state until a hole is formed in the liquid bladder at which time the compressed material adjacent to the hole expands to at least partially plug the hole
Data Source
AI summary
A self-sealing liquid bladder having a plurality of layers including a liquid impermeable material layer that is compatible with a liquid held in the bladder and at least one sealing layer that is conformally arranged to span a surface area of the liquid impermeable material layer and that is separated from a liquid held in the bladder by the liquid impermeable layer, the sealing layer including a sealing means that, in response to a penetration of both the liquid impermeable material layer and the sealing layer, substantially seals the penetration.