Elongated Gas Generator Combustion Uniformity
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Solution Overview
Problem
Existing gas generators for side airbags face issues with uneven gas generation and pressure buildup, leading to potential fractures and incomplete combustion due to restricted gas flow in elongated shapes, particularly in side collision scenarios.
Innovation Solution
A gas generator design featuring a cylindrical housing with an ignition device at one end and a diffuser portion at the other, incorporating a cylindrical member with a gap and an obstacle to disrupt axial gas flow, along with strategically placed gas passage holes to enhance gas flow and combustion efficiency, allowing for improved ignition and combustion of the gas generating agent across the length of the generator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If gas generating material is disposed in an elongated space with restricted gas flow paths, then the gas generator can be mounted in limited side collision spaces, but uneven gas generation and pressure buildup occur leading to potential fractures and incomplete combustion
Solution Approach 1:
The gas generator is divided into multiple combustion chambers separated by partitions with openings. Each chamber contains gas generating material and has dedicated gas flow paths through the partitions. This segmentation allows independent combustion in each chamber, preventing pressure buildup that would cause fractures while ensuring complete combustion in each segment, thus resolving the contradiction between compact elongated size and combustion reliability
Solution Approach 2:
Gas flow paths are created in multiple dimensions by forming passages through the partitions between combustion chambers. The gas can flow axially through the elongated housing and radially through the partition openings, creating a three-dimensional gas flow network. This multi-dimensional flow path system prevents pressure buildup in any single direction while maintaining the compact elongated shape required for side collision mounting
2Area of stationary object
If gas flow path is restricted in elongated shape gas generator, then mounting space is reduced, but gas flow is limited causing pressure buildup and potential part fracture
Solution Approach 1:
The elongated housing is segmented into multiple combustion chambers by partitions, each with controlled openings. This segmentation creates multiple localized combustion zones that can manage pressure independently, preventing excessive pressure buildup that would cause part fracture while maintaining the compact elongated form factor for limited mounting spaces
Solution Approach 2:
Gas flow paths through the partitions are pre-designed and pre-formed during manufacturing. The openings in the partitions are strategically positioned and sized to control gas flow distribution before combustion occurs. This preliminary configuration of flow paths ensures that gas can escape evenly from each combustion chamber, preventing pressure buildup before it reaches critical levels that would cause fracture
3Productivity
If gas generating material is burned in elongated space with axial gas flow, then gas can be discharged through diffuser portion, but combustion is uneven and incomplete in certain portions
Solution Approach 1:
The combustion process is segmented into multiple independent chambers separated by partitions. Each chamber undergoes combustion independently with controlled gas flow through its specific openings in the partitions. This segmentation ensures uniform combustion across all chambers simultaneously, preventing the uneven and incomplete combustion that occurs in single-elongated chamber designs while maintaining rapid gas discharge through the diffuser portion
Solution Approach 2:
Each combustion chamber is given identical local conditions including the same partition opening configurations and gas generating material placement. This local quality uniformity across all chambers ensures that combustion proceeds evenly throughout the entire elongated structure, with each chamber producing gas at the same rate and completing combustion uniformly, thereby achieving both high productivity and combustion reliability
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 design ensures uniform gas generation and early discharge, improving the ignition and combustion ability of the gas generating agent, even in elongated shapes, while reducing the risk of part failure and ensuring complete combustion, thus enhancing the reliability and performance of the gas generator.
Implementation Method 1
the gas generating agent ignited and burned by actuation of the ignition device and when gas is generated
Implementation Method 2
an obstacle provided in the gap to limit a flow of gas passing axially through the gap
Implementation Method 3
at least part of the gas flowing through the first gas passage hole into the gap, part of the gas, that has passed therethrough, flowing again into the cylindrical member through the second gas passage hole to aid the combustion of the gas generating agent
Implementation Method 4
a cylindrical gap being formed between the cylindrical member and an inner wall surface of the cylindrical housing and leading to the gas discharge port
Data Source
Figure 1
Figure 2~3(b)
Figure 4
AI summary
A cylindrical housing is mounted with an igniter and a diffuser portion having a gas discharge port. A cylindrical member is disposed and fixed in the housing so as to form a cylindrical gap reaching the gas discharge port. An obstacle is provided in the gap, and a first gas passage hole, a second gas passage hole and a third gas passage hole are formed. A gas generating agent is ignited and burnt by activation of the igniter to generate gas, part of the generated gas flows into the gap through the first gas passage hole (f1), part of the gas that has passed therethrough flows again into the cylindrical member through the second gas passage hole (f2) to aid the combustion of the gas generating agent, and then the gas flows into the gap through the third gas passage hole (f3) and finally is discharged from the gas discharge port.