Crash Survivable Memory Unit Sacrificial Phase-Change Thermal Protection
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Solution Overview
Problem
Current crash survivable memory units for flight recorders face limitations in thermal protection, as existing methods do not adequately address the need for advanced thermal protection across various aviation and transportation standards, particularly in terms of cost-effectiveness and adaptability to different environments.
Innovation Solution
The implementation of a housing with a sacrificial material having a lower melting temperature than the primary material, which changes state and creates an air gap when exposed to heat, providing additional thermal protection for the heat-sensitive memory devices by absorbing heat and reducing conductive and convective heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional thermal insulation materials (dry-silica) are used to protect memory boards, then high-temperature thermal protection is provided, but the device complexity and cost increase
Solution Approach 1:
The patent employs a sacrificial material that undergoes phase transition from solid to liquid at a specific temperature (e.g., 150°C). This phase change absorbs thermal energy and creates a liquid barrier that blocks heat transfer to the memory device, providing thermal protection without requiring complex multi-layer insulation structures.
Solution Approach 2:
The sacrificial material is designed to be consumable and temporary. It melts and is expelled through openings in the housing during thermal events, sacrificing itself to protect the valuable memory device. This disposable approach replaces expensive, complex permanent insulation systems with a simple, low-cost sacrificial layer.
2Temperature
If thick insulation layers are used to protect against extreme heat, then thermal protection is improved, but the housing volume and weight increase
Solution Approach 1:
The sacrificial material utilizes phase transition to provide thermal protection in a thin layer. When heated, it melts and expands, creating a liquid barrier that effectively blocks heat transfer. This phase-change mechanism provides superior thermal protection per unit thickness compared to traditional solid insulation materials, reducing the required housing volume.
Solution Approach 2:
The patent uses a composite structure combining a sacrificial material layer with the housing material. The sacrificial material (e.g., polymer or wax-based substance) is integrated into the housing wall structure, creating a multi-functional composite that provides both structural integrity and thermal protection without requiring separate thick insulation layers.
3Temperature
If multiple layers of protective materials are used, then thermal protection is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent merges the sacrificial material layer with the housing manufacturing process. The sacrificial material is integrated into the housing wall structure during a single molding or fabrication step, eliminating the need for separate assembly steps to install insulation layers. This integration simplifies manufacturing while maintaining thermal protection functionality.
Solution Approach 2:
The phase-change property of the sacrificial material provides passive thermal protection that activates automatically during thermal events. This eliminates the need for complex active thermal management systems, control mechanisms, or multiple active components, thereby simplifying the overall manufacturing process.
4Temperature
If sacrificial material is used to create air gap and absorb heat, then thermal protection is improved, but the material is consumed and must be replaced
Solution Approach 1:
The sacrificial material is intentionally designed as a low-cost, consumable component that protects the valuable memory device. It is expelled through openings in the housing during thermal events, and the housing can be designed to allow for easy replacement of the sacrificial material layer. The low cost of the sacrificial material makes this disposable approach economically viable.
Solution Approach 2:
The patent converts the harmful effect of heat into a beneficial protective mechanism. When thermal events occur, the heat that would damage the memory device instead triggers the sacrificial material to melt and expand, creating a protective liquid barrier. The harmful thermal energy is thus converted into a beneficial protective action that actively blocks further heat transfer.
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
This solution enhances the thermal protection of memory units by absorbing heat and creating an air gap, effectively protecting vital flight data and reducing damage from extreme temperatures, thereby improving the survivability of flight recorders in severe accidents.
Implementation Method 1
The sacrificial material has a lower melting temperature than the first material such that the sacrificial material changes state and egresses through the openings in the housing when exposed to heat to create an air gap between the housing and heat sensitive memory device
Implementation Method 2
the sacrificial material changes state and egresses through the openings in the housing when exposed to heat
Data Source
AI summary
A flight recorder includes an information input device, heat sensitive memory device electrically connected to the information input device, and housing enclosing the heat sensitive memory device. The housing is made with a first material and having a plurality of openings made through the housing. A sacrificial material is disposed between the housing and heat sensitive memory device. The sacrificial material having a lower melting temperature than the first material such that the sacrificial material changes state and egresses through the openings in the housing when exposed to heat to create an air gap between the housing and heat sensitive memory device. The first material includes nickel and the sacrificial material includes aluminum. A heat insulating layer is disposed between the sacrificial material and heat sensitive memory device. A second sacrificial material is disposed between the heat insulating layer and heat sensitive memory device.