Cylindrical Filter End Geometry for Stable Pyrotechnic Gas Sealing
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Solution Overview
Problem
Existing pyrotechnic devices, such as gas generators for airbag systems, face challenges in ensuring stable and efficient contact between the cylindrical filter and the housing, leading to potential short-pass of combustion gases and inadequate capture of residues and metal fragments.
Innovation Solution
The cylindrical filter features weakened portions on its annular end surfaces that deform to enhance contact with the housing, forming annular surfaces for stable engagement, thereby preventing gas short-pass and improving residue capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the cylindrical filter is manufactured with a rigid structure, then the manufacturing precision is improved, but the contact stability with the housing deteriorates
Solution Approach 1:
The cylindrical filter transitions from a static rigid structure to a dynamic structure with deformable weakened portions. The weakened portions can elastically deform to adapt to dimensional variations in the housing, maintaining stable contact while the overall cylindrical shape is preserved. This dynamic adaptation resolves the contradiction between manufacturing precision and contact stability.
Solution Approach 2:
The patent introduces weakened portions with reduced thickness parameters compared to the main cylindrical wall. This parameter change creates regions of controlled flexibility that allow the filter to deform and accommodate housing variations, improving contact stability without compromising the overall structural integrity and manufacturing precision of the filter.
2Strength
If the cylindrical filter is made with uniform thickness, then the structural strength is improved, but the adaptability to housing variations deteriorates
Solution Approach 1:
The cylindrical filter employs non-uniform thickness distribution with weakened portions having reduced thickness compared to the main body. This local quality variation creates specific regions that are more compliant and adaptable to housing dimensional variations, while the majority of the filter maintains sufficient thickness for structural strength and filtration effectiveness.
Solution Approach 2:
The weakened portions provide controlled flexibility that allows the filter to dynamically adapt its shape to match housing variations. This dynamic adaptation capability enables the filter to maintain reliable contact across different dimensional tolerances while the overall structure retains adequate strength for its filtration function.
3Ease of manufacture
If the end surfaces are made flat, then the manufacturing ease is improved, but the contact area with the housing deteriorates
Solution Approach 1:
The end surfaces transition from static flat geometry to dynamic deformable structures with weakened portions. During assembly, these weakened portions deform to conform to the housing surfaces, significantly increasing the contact area from a theoretical line contact to an extended surface contact, while maintaining manufacturing simplicity through the punching and winding process.
Solution Approach 2:
The weakened portions extend the contact interaction into the radial dimension by deforming outward to match the housing inner surface. This dimensional transformation converts what would be a limited line contact into an extended surface contact area, improving sealing and stability without complicating the manufacturing process.
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 enhanced contact and deformation of the weakened portions ensure stable filtration and effective capture of combustion residues, improving the performance of pyrotechnic devices like gas generators in airbag systems.
Implementation Method 1
at least one of the weakened portion of the first annular end surface or the weakened portion of the second annular end surface of the cylindrical filter being deformed in a radial direction
Data Source
AI summary
A cylindrical filter for a pyrotechnic device, including a gas generating agent or pressurized gas as a gas generation source, includes a first annular end surface, a second annular end surface positioned opposite to the first annular end surface, and a cylindrical wall surface between the first annular end surface and the second annular end surface. At least one of the first and second annular end surfaces includes a weakened portion. The weakened portion, when provided in the first annular end surface, includes a first annular wall portion protruding from the first annular end surface and has a thickness less than a thickness of the first annular end surface. The weakened portion, when provided in the second annular end surface, includes a second annular wall portion protruding from the second annular end surface and has a thickness less than a thickness of the second annular end surface.