Cylindrical Filter with Localized Compressive Strength for Gas Sealing
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Solution Overview
Problem
Existing cylindrical filters for gas generators, made from expanded metal or metal lath, suffer from low elasticity and gaps at abutting portions, leading to combustion gas short-passing issues, necessitating additional cushion members for prevention.
Innovation Solution
A cylindrical filter with a porous metal plate structure, where the compressive strength is intentionally reduced at specific regions to facilitate press-contact with the housing, eliminating the need for separate short-passing prevention members and enhancing attachment strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If expanded metal or metal lath is used as a filter to reduce weight, then weight is reduced, but elasticity is low and gaps form at abutting portions causing combustion gas short-passing
Solution Approach 1:
The filter employs different materials for different regions: expanded metal or metal lath for the main body (weight reduction), and elastic rubber material at the abutting portions (sealing). This local differentiation resolves the contradiction by assigning optimal material properties to specific functional zones.
Solution Approach 2:
The filter combines dissimilar materials (metallic expanded metal/metal lath with rubber sealing portions) to achieve properties that neither material alone could provide: the metal provides structural integrity and weight reduction, while the rubber provides elasticity and sealing.
2Weight of moving object
If expanded metal or metal lath is used as a filter, then weight is reduced, but additional cushion members are required to prevent short-passing, increasing device complexity
Solution Approach 1:
The sealing function, previously requiring a separate cushion member, is merged into the filter structure itself through the elastic rubber portions integrated at the abutting ends. This eliminates the need for additional components while maintaining the weight benefits of expanded metal.
Solution Approach 2:
The elastic rubber portions serve multiple functions: they provide sealing to prevent short-passing, act as cushions to resolve gaps, and facilitate press-contact with the housing. This multi-functionality replaces what would otherwise require separate components.
3Weight of moving object
If the filter is made from materials with low elasticity like expanded metal, then weight is reduced, but gaps at abutting portions are less likely to be resolved
Solution Approach 1:
The filter employs different materials for different regions: expanded metal or metal lath for the main body (weight reduction), and elastic rubber material at the abutting portions (sealing). This local differentiation resolves the contradiction by assigning optimal material properties to specific functional zones.
Solution Approach 2:
The filter combines dissimilar materials (metallic expanded metal/metal lath with rubber sealing portions) to achieve properties that neither material alone could provide: the metal provides structural integrity and weight reduction, while the rubber provides elasticity and sealing.
Data Source
Figure 1~2
Figure 3~4(b)
Figure 5
AI summary
The present invention provides a cylindrical filter for a gas generator, including: a plurality of layers made of a porous metal plate in which a compressive strength (S1) of a predetermined region in at least one end in the height direction is set smaller than a compressive strength (S2) of a portion other than the S1 region, the porous metal plate being selected from the group consisting of expanded metal, metal lath, and perforated metal, and the S1 region corresponding to a region of 5 to 20% in length from both ends with respect to the overall height.