Intumescent Cable Conduit Fire Protection Aircraft
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Solution Overview
Problem
The production of fire-resistant cable looms for aircraft is costly and labor-intensive, and existing solutions require significant expenditure for modifications or repairs, as they are typically manual and require opening the protective sheath for adding or removing cables.
Innovation Solution
A fire-resistant cable conduit using an intumescent material that expands up to 30 times its initial volume during a fire, forming a high-temperature resistant foam layer to shield electrical lines, with a slit design for easy insertion and removal of cables, and a reinforced sheath to maintain mechanical stability and prevent uncontrolled expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional multi-layer protective sheath is used for fire resistance, then fire protection is improved, but manufacturing cost and labor intensity increase significantly
Solution Approach 1:
The patent uses a composite structure consisting of an intumescent core material (expandable graphite or vermiculite) enclosed within a polymer sheath. This composite design provides fire resistance through the intumescent material's expansion capability while the polymer sheath offers structural integrity and ease of manufacturing, replacing the complex multi-layer traditional protective sheath.
Solution Approach 2:
The patent utilizes the parameter change of the intumescent material when exposed to fire - the material undergoes a phase transition from a compact state to an expanded state (expanding up to 30 times its original volume). This parameter change creates an insulating barrier that provides fire protection without requiring complex manufacturing processes.
2Reliability
If traditional protective sheath is used, then fire resistance is achieved, but cable installation and modification become extremely difficult and expensive
Solution Approach 1:
The patent introduces a longitudinal slit that divides the otherwise continuous protective structure into two separable halves. This segmentation allows cables to be inserted or removed by simply opening the slit, eliminating the need to dismantle the entire protective sheath while maintaining fire resistance through the intact intumescent material.
Solution Approach 2:
The patent creates a dynamic structure where the protective sheath can transition between a closed state (providing fire protection) and an open state (allowing cable access). The longitudinal slit enables this dynamic behavior, allowing the structure to adapt to installation and maintenance requirements while preserving its fire-resistant properties.
3Reliability
If intumescent material expands during fire, then fire protection is enhanced, but structural stability may be compromised
Solution Approach 1:
The patent employs a nested structure where the intumescent core material is enclosed within the polymer sheath. The outer sheath acts as a container that constrains the expanding intumescent material during fire exposure, directing its expansion in a controlled manner while preventing uncontrolled structural failure. This nested arrangement allows the inner material to perform its fire-protection function without compromising overall structural stability.
Solution Approach 2:
The patent uses the polymer sheath as a counteracting structure that balances the expansion forces of the intumescent material. The sheath provides mechanical strength and structural integrity that counterweights the destabilizing effect of the expanding core material, maintaining structural stability while allowing the fire-protection mechanism to function.
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 cable conduit maintains electrical functionality at temperatures over 900°C for at least 5 minutes, reduces maintenance and repair costs, and provides effective fire protection by creating a spacer between electrical lines and flames, allowing for easy cable management without significant production expenditure.
Implementation Method 1
an intumescent plastic foam expands its volume by a multiple, such as up to 30-times the initial volume, and is capable of forming a high-temperature resistant foam layer
Implementation Method 2
an intumescent body may be able to shield the electrical lines contained within it from the effect of fire... an intumescent plastic foam material may be completely carbonized
Implementation Method 3
an intumescent plastic foam material may be completely carbonized. Thus, only an 'inorganic' foam material remains, free of any plastic
Implementation Method 4
the temperature does not exceed 200° C. within the interior of the tubular body for 5 minutes, such that the electrical function of the cables contained in the cable conduit is protected
Data Source
AI summary
A fire-retarding cable conduit for electrical lines in regions potentially exposed to fire in aircraft, has a tubular base body including an interior space for accommodating the electrical lines and may include a sheath. The base body comprise a plastic foam material, which in the event of a fire is intumescent the intumescent foam may form a material that is substantially free of plastic when exposed to fire. A continuous longitudinal slit may be provided for inserting the electrical lines into the tubular base body and may use a form that protects the lines during exposure to fire.