Fuel-Rich Monolithic Grain Inflator with Oxidant-Enhanced Combustion
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Solution Overview
Problem
Existing airbag inflator devices struggle to efficiently inflate large volume airbags within the required time, especially for side-impact and roll-over restraint systems, and there is a need for a compact, lightweight, and economical solution that provides superior inflation performance.
Innovation Solution
The development of an inflator device with a fuel-rich monolithic gas generant grain and a pressurized gas storage chamber containing a gaseous oxidizer, where the initiator device generates a shock wave to open a temporary closure, allowing combustion gas and stored gas to rapidly inflate airbags with volumes greater than 45 liters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional gas generating material is used in an inflator device, then the device can be simpler in structure, but it cannot efficiently inflate large volume airbags within the required time
Solution Approach 1:
The gas generating material is segmented into a monolithic grain structure with internal flow channels, allowing the combustion to propagate systematically through the grain while maintaining a compact overall structure. This segmentation enables rapid gas generation without requiring a larger or more complex inflator device.
Solution Approach 2:
The monolithic grain incorporates a porous internal structure with flow channels that allow oxidant-enhanced combustion to penetrate and propagate through the fuel-rich material. This porous architecture enables rapid and complete combustion, significantly increasing inflation speed while keeping the grain size compact.
2Weight of moving object
If the inflator device is made compact and lightweight, then it is more economical and easier to install, but it has difficulty providing sufficient gas for large volume airbags
Solution Approach 1:
The invention uses oxidant-enhanced combustion where concentrated oxidant is delivered through the porous monolithic grain structure. This accelerated oxidation process extracts significantly more energy and gas volume per unit mass of fuel, enabling a compact and lightweight inflator to generate sufficient gas for large volume airbags.
Solution Approach 2:
The gas generating system uses a composite formulation combining fuel-rich monolithic grain material with integrated oxidant delivery. This composite structure maximizes the energy density and gas generation efficiency, allowing a reduced-size inflator to produce the required gas volume for large airbags.
3Productivity
If a fuel-rich monolithic grain with oxidant-enhanced combustion is used, then rapid inflation of large airbags is achieved, but the combustion process becomes more complex
Solution Approach 1:
The oxidant is pre-positioned within the porous monolithic grain structure before combustion begins. This preliminary arrangement of oxidant and fuel in intimate contact eliminates the need for complex real-time mixing mechanisms, simplifying the overall device while enabling rapid oxidant-enhanced combustion for fast inflation.
4Ease of manufacture
If conventional combustion is used, then the device is simpler to manufacture, but undesirable effluent species are produced
Solution Approach 1:
The oxidant-enhanced combustion process ensures more complete oxidation of the fuel-rich material, converting potentially harmful partially-combusted effluent species into less harmful fully-oxidized products. This approach maintains manufacturing simplicity while significantly reducing undesirable emissions.
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 enables rapid inflation of large airbags, improving deployment reliability and reducing undesirable effluent species, while maintaining a compact and lightweight design suitable for large volume airbag applications.
Implementation Method 1
the initiator device generates a shock wave that propagates through the one or more flow channels in the fuel-rich gas generant grain
Implementation Method 2
the pressurized stored gas comprises at least one gaseous oxidizer capable of reacting with the gas products produced by the fuel-rich gas generant grain
Data Source
Figure 1~2
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AI summary
The disclosure provides an inflator device (200) for a restraint device like an airbag. A fuel-rich gas generant grain (220) is located in actuating proximity to an initiator device (210). The grain (220) has at least one flow channel (222)through which a shock wave generated by the initiator device (210) passes. The shock wave opens a burst disc (250) between the inflator housing and downstream airbag (208) to permit gases to flow into the airbag. A chamber (240) storing pressurized gas (242) (having at least one oxidant, e.g., O2) is also disposed within the inflator device (200). Upon initiator actuation, the oxidant can react with combustion products of the initiator and the fuel-rich gas generant and flow into the airbag for rapid inflation. Methods of inflating airbags and airbag deployment are provided. Such inflators are particularly suitable for large volume (greater than 60 liter) airbags.