Gas Generator Thermal Barrier Design
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Solution Overview
Problem
Pyrotechnic gas generators for airbag systems face issues with excessive temperature increase in the housing after actuation, which can damage the airbag and pose a risk to occupants, due to heat transfer from combustion residues to the filter and housing.
Innovation Solution
A gas generator design featuring a diffuser shell and closure shell with a heat-transfer inhibiting space between the top plate and the first support member, where the filter is supported by a disk-shaped portion with communication holes and a cylindrical wall portion, allowing combustion gas to pass through while preventing direct heat transfer to the top plate, and utilizing a second support member to direct heat to the circumferential wall plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the filter is arranged inside the housing in direct contact with the housing or in indirect contact with the housing, then the filter is supported and combustion residues are collected, but the housing temperature rises excessively after actuation
Solution Approach 1:
A support member is introduced as an intermediary component between the filter and the housing. This support member has a first end that supports the filter and a second end that is spaced from the housing, creating a thermal barrier that prevents direct heat transfer from the filter to the housing while maintaining structural support
Solution Approach 2:
The support member extends in the axial direction with its second end spaced from the housing, creating a three-dimensional spatial relationship that introduces thermal insulation through distance rather than requiring additional insulating materials
2Strength
If the top plate is in direct contact with the first support member, then structural support is maintained, but heat transfers directly to the top plate causing excessive temperature increase
Solution Approach 1:
The first support member acts as an intermediary with thermal barrier properties, supporting the filter while its second end remains spaced from the top plate, preventing direct thermal contact while maintaining mechanical support function
Solution Approach 2:
The spaced relationship between the support member and housing/top plate is designed in advance to prevent excessive heat transfer, cushioning against the thermal hazard before it can affect the housing temperature
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
Effectively inhibits the excessive increase in temperature of the housing facing the occupant, maintains filter performance, and prevents heat transfer from combustion residues to the top plate, ensuring the airbag remains intact and occupant safety.
Implementation Method 1
the combustion gas passes through the filter or collides therewith before the combustion gas is discharged from the housing, thereby causing the residues contained in the combustion gas to adhere to the filter
Implementation Method 2
After actuation, the heat of the residues and the combustion gas is transferred to the filter and the filter is heated to a high temperature
Implementation Method 3
A gas generator design featuring a diffuser shell and closure shell with a heat-transfer inhibiting space between the top plate and the first support member
Data Source
Figure 1
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Figure 3
AI summary
The invention provides a gas generator (1) including, a housing (10) with an ignition device chamber (30) and a combustion chamber (40), an annular or flat-plate filter (50) disposed to face a top plate of the housing and to be spaced from the upper circumferential wall plate, a first support member including a disk-shaped portion abutting against an upper surface of the filter (60), the disc-shaped portion including communication holes (66) only at a section in contact with the upper surface of the filter, a second support member (70) including an annular flat portion abutting against a lower surface of the filter and cylindrical wall portion fixed to the housing, wherein during actuation, a gap is formed between the top plate and the first support member, such that the top plate is deformed. Support member can be provided as a one-piece element.