Helical Wire Rod Filter for Airbag Gas Generator Residue Collection
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Solution Overview
Problem
Conventional air bag gas generators face challenges in collecting liquid combustion residues due to inadequate heat sink and elasticity issues with existing filters, leading to potential damage and inefficiencies in gas purification.
Innovation Solution
A filter design featuring a first layer of helically wound wire rods with a specific cross-sectional area and pitch angle, combined with a second layer of finer filter particle size, enhances residue collection and cooling performance, preventing short passes and ensuring reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire mesh layers are used to collect combustion residue, then filtering function is provided, but liquid combustion residue cannot be collected and wire mesh may melt due to insufficient heat sink function
Solution Approach 1:
The patent changes the physical parameters of the filter by using wire rods with specific cross-sectional area (0.03 to 0.8 mm²) and specific material properties instead of conventional wire mesh. This parameter change enables the filter to withstand combustion temperatures while effectively collecting liquid residue through controlled porosity and thermal mass.
Solution Approach 2:
The filter employs a composite structure combining wire rods with specific material composition that provides both high temperature resistance and effective residue collection. The composite nature of the wire rod material delivers simultaneous thermal stability and filtration capability that single-material solutions cannot achieve.
2Reliability
If plain weave wire mesh is wound in multiple layers, then filtering capacity is increased, but end surface becomes uneven and short passes occur
Solution Approach 1:
The patent replaces the flat planar structure of conventional wire mesh with a curved helical configuration. The wire rod is wound in a helix pattern around a central axis, creating a cylindrical filter structure where the curvature eliminates the uneven end surface problem inherent in flat multi-layer mesh configurations.
Solution Approach 2:
The invention transitions from a two-dimensional planar wire mesh structure to a three-dimensional helical structure. By adding the dimensional aspect of helical winding around a central axis, the filter achieves uniform gas flow distribution and eliminates short passes while maintaining effective filtration surface area.
3Weight of moving object
If wire rods with small cross-sectional area are used, then filter weight is reduced, but heat sink function becomes inadequate and wire rods may melt
Solution Approach 1:
The patent establishes an optimal parameter range for wire rod cross-sectional area (0.03 to 0.8 mm²) that balances weight reduction with temperature resistance. Within this range, the wire rods possess sufficient thermal mass to function as heat sinks while maintaining lightweight characteristics and effective residue collection capability.
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 filter effectively collects and cools combustion residues, preventing damage and ensuring clean gas generation with improved reliability and weight efficiency in air bag inflation systems.
Implementation Method 1
the wire mesh layers to which the gas of high temperature has initial contact should be able to fulfill a heat sink-like role
Implementation Method 2
a first layer formed by the helical winding of wire rods having cross-sectional area 0.03 to 0.8 mm² on a section that has initial contact with the gas generated by the combustion of the gas generating agent
Implementation Method 3
pyrotechnic gas generators employ a filter for collecting the combustion residue
Data Source
AI summary
A filter for a gas generator in which the manufacture is simple, which has an adequate filter performance and cooling performance and, furthermore, which has high reliability with little damage caused in actuation of the gas generator, is provided. The filter for an air bag gas generator comprises a first layer formed from helically wound wire rods having a cross-sectional area of 0.03 to 0.8 mm2, in such a way that the pitch angle of wire rods vertically superposed in the radial direction is symmetrical, and a second layer that exists on the outer side of the first layer in the radial direction and is formed to have a finer filter particle size than the first layer using a wire rod narrower than the wire rod that forms the first layer.