Flexible heat shield with silicone elastomer and a topcoat for inflatible safety devices
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Solution Overview
Problem
Conventional heat shields for inflatable safety devices are inadequate as they either provide limited protection due to thin coatings or become bulky and inflexible with thick rubber sheets, leading to assembly issues and increased weight, which can cause burn-through of airbag fabrics during pyrotechnic inflator deployment.
Innovation Solution
A thermally resistant layered composite sheet comprising a fabric layer and a thermal barrier layer with silicone elastomer and topcoats, providing enhanced thermal resistance at high temperatures, reducing the risk of burn-through and allowing for a more flexible and lightweight design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If thin silicone coatings are used for heat shield, then the airbag remains lightweight and flexible, but the thermal protection is insufficient and burn-through occurs
Solution Approach 1:
The patent applies composite materials by combining multiple layers including fabric layers, silicone elastomer layers, and thermally resistant coatings to create a heat shield that provides both adequate thermal protection and maintains flexibility. The composite structure allows each layer to contribute specific properties: fabric provides structural integrity, silicone elastomer provides thermal resistance, and the combination achieves protection without excessive weight or bulk.
2Reliability
If thick rubber sheets are used for heat shield, then thermal protection is improved, but the airbag becomes bulky and assembly becomes difficult
Solution Approach 1:
The heat shield is segmented into multiple thin layers rather than using a single thick rubber sheet. This segmentation allows each layer to be thin and flexible for easy assembly, while the cumulative effect of multiple layers provides adequate thermal protection. The layered structure can be sewn and assembled more easily than a thick monolithic sheet.
Solution Approach 2:
The patent uses composite materials with multiple functional layers including fabric and silicone elastomer in specific configurations. This composite approach achieves thermal protection equivalent to thick rubber sheets while maintaining flexibility and ease of assembly, as each layer contributes specific properties and the overall structure remains thin.
3Reliability
If thick rubber sheets are used for heat shield, then thermal protection is improved, but the coefficient of friction increases making sewing difficult
Solution Approach 1:
By segmenting the heat shield into multiple thin layers rather than using a single thick sheet, the fabric surfaces remain accessible for sewing operations. The thin layers can be sewn through more easily, and the segmentation allows sewing to occur on fabric surfaces rather than through thick rubber material.
Solution Approach 2:
The patent employs flexible thin films and layers including fabric and silicone elastomer instead of thick rigid rubber sheets. These thin flexible layers maintain the necessary thermal protection while allowing standard sewing operations to proceed easily, as needles can penetrate the thin layers without excessive friction or resistance.
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 composite sheet offers extended thermal resistance at 725°C, reducing the risk of burn-through and enabling a more flexible and lightweight heat shield that simplifies assembly and reduces weight, while maintaining effective protection against high temperatures.
Implementation Method 1
The composite sheet exhibits a thermal resistance value of six seconds or more at 725°C in a thermal penetration test
Implementation Method 2
The silicone topcoat comprises an organopolysiloxane having one or more silicon atom-bonded alkenyl groups on average in one molecule: an organohydrogenpolysiloxane; a hydrosilylation reaction catalyst present in any amount capable of curing the coating composition
Data Source
Figure 1
Figure 2(A)~3(E)
Figure 4(A)~4(J)
AI summary
An inflatable vehicle safety device is provided that comprises an inflator, a fluid compartment, and a heat shield. The inflator is capable of providing an inflation fluid used to inflate the fluid compartment. The heat shield, which is located within the fluid compartment, comprises a fabric layer and a thermal barrier layer located adjacent to the film. The barrier layer includes at least one layer of silicone elastomer and one or more topcoats. The heat shield has a thermal resistance value of six seconds or more at 725°C when tested in a hot rod thermal resistivity test.