Multi-vent Airbag Inflator Particulate Reduction
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Solution Overview
Problem
Hybrid automotive airbag inflators using non-ammonium nitrate-based pyrotechnic materials generate higher particulate levels, requiring effective filtration to prevent blockages and ensure timely gas release, and existing designs are vulnerable to blockages due to a single centrally located orifice.
Innovation Solution
The design incorporates multiple orifices with a longer, tortuous flow path and an internal diverter to reduce particulate exit and protect against blockages, allowing for varied performance outcomes based on temperature and pressure conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If non-ammonium nitrate-based pyrotechnic materials are used, then gas generation capability is improved, but particulate generation increases requiring filtration
Solution Approach 1:
A diverter component is introduced as an intermediary element between the pyrotechnic material and the orifice. This diverter protects the orifice from particulate matter while allowing gas to pass through, effectively mediating between the harmful particulate generation and the need for clean gas flow to the airbag
2Device complexity
If a single centrally located orifice is used, then device complexity is reduced, but vulnerability to blockage increases
Solution Approach 1:
The single orifice is segmented into multiple orifices distributed around the periphery of the pressure vessel. This segmentation ensures that if one orifice becomes blocked, gas can still flow through the other orifices, thereby improving reliability without significantly increasing overall system complexity
3Object-generated harmful factors
If a longer tortuous flow path is created, then particulate reduction is improved, but gas release time may be extended
Solution Approach 1:
The flow path is configured to extend in multiple dimensions within the pressure vessel, creating a tortuous path that increases particulate deposition opportunities without significantly extending the axial length of the device. This dimensional approach allows longer effective flow path while maintaining compact overall size and reasonable gas release timing
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 solution effectively reduces particulate exit and risk of pin holes in the airbag cushion by extending the burning process of propellant slivers and protecting orifices from debris, enabling efficient gas release and adaptable performance.
Implementation Method 1
The pyrotechnic materials are used for gas generation and heating of the stored gas
Implementation Method 2
The longer, more torturous flow path reduces the overall amount of particulate exiting the inflator
Data Source
AI summary
An airbag inflator includes a pressure vessel with a bottom portion, a top portion and a center structure connecting the bottom portion and the top portion. The top portion includes an exit orifice that is closed with a rupturable membrane. An energetics cover attached to the center structure houses a pyrotechnic material, and a diverter is attached to the top portion. The pressure vessel, the energetics cover and the diverter define a gas flow path from inside the energetics cover toward the bottom portion of the pressure vessel, the gas flow path turning at least a first 180 degrees toward the top portion of the pressure vessel and between the energetics cover and the pressure vessel. The longer gas flow path allows time for multi-perforation grain slivers to burn up before exiting the inflator, thereby reducing the amount of particulate exiting the inflator.