Gas Generator Combustion Chamber Segmentation for S-Curve Deployment
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Solution Overview
Problem
Existing gas generators for airbag systems face challenges in achieving an S-shaped output curve for airbag deployment, as they either have improved ignition but struggle with efficient combustion gas discharge or separate combustion chambers that are influenced by ambient temperature, leading to suboptimal gas discharge patterns.
Innovation Solution
A gas generator design featuring a combustion chamber with distinct 'initial ignition' and 'late ignition' spaces, where the inner cylindrical wall portion creates a radial communication path for early ignition and delayed ignition of the gas generating agent, controlled by the annular partition wall and gas-flow holes, allowing for a timed difference in ignition and combustion, thereby achieving the desired S-shaped output curve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gas generating agent is ignited from a portion facing the ventilating portion near the bottom plate, then ignition performance is improved, but the combustion gas discharge pattern cannot achieve the desired S-shaped output curve
Solution Approach 1:
The combustion chamber is segmented into a first combustion chamber (with gas generating agent) and a second combustion chamber (without gas generating agent), separated by a partition wall with communication holes. This segmentation allows different regions to serve different functions: the first chamber ensures reliable ignition while the second chamber controls the gas discharge pattern to achieve the S-shaped output curve.
Solution Approach 2:
The partition wall with communication holes acts as an intermediary structure between the two combustion chambers. It allows controlled interaction between the chambers - enabling ignition propagation from the first to the second chamber while maintaining separate functional zones for ignition and gas discharge control.
2Reliability
If high-temperature combustion gas flows axially upward from the bottom, then ignition of unburned gas generating agent is improved, but the gas discharge pattern deviates from the S-shaped curve requirement
Solution Approach 1:
The combustion chamber is divided into two distinct chambers with different functional requirements. The first chamber handles initial combustion with upward flow for complete ignition, while the second chamber manages the gas discharge phase to produce the S-shaped output curve, resolving the contradiction between combustion completeness and discharge pattern.
Solution Approach 2:
Different regions of the combustion system are given different local qualities: the first combustion chamber is designed for high-temperature combustion and complete ignition, while the second combustion chamber is optimized for controlled gas discharge. The partition wall with selective communication holes creates localized flow paths that satisfy both requirements in different spatial zones.
3Reliability
If the combustion chamber is separated into two chambers by a barrier, then ignition control is improved, but the system becomes more complex and is influenced by ambient temperature
Solution Approach 1:
The combustion chamber is segmented into two chambers separated by a partition wall with communication holes. This segmentation provides improved ignition control by allowing sequential combustion while maintaining a relatively simple overall structure that minimizes ambient temperature influence through the enclosed design.
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
This design effectively creates a timed difference in ignition and combustion, ensuring efficient combustion gas discharge and achieving the S-shaped output curve for effective airbag deployment, even with a single ignition device.
Implementation Method 1
a combustion product, which is generated in the ignition device chamber, passing through the first communication portion, then colliding with the inner cylindrical wall portion, changing a flow direction toward the top plate
Implementation Method 2
a combustion chamber enclosed by the top plate, the bottom plate, the ignition device chamber housing, and the outer cylindrical wall portion and being charged with a gas generating agent therein
Data Source
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AI summary
The present invention provides a gas generator for a restraining device, including: a housing; an ignition device chamber housing and an outer cylindrical wall portion disposed inside the housing; and an annular partition wall portion forming a space near a top plate between the ignition device chamber housing and the outer cylindrical wall portion, a portion defined by the top plate and a bottom plate of the housing, the ignition device chamber housing and the outer cylindrical wall portion is a combustion chamber charged with a gas generating agent; an inner cylindrical wall portion, disposed on the housing bottom plate and spaced from the annular partition wall portion, is provided inside the combustion chamber; the ignition device chamber and the combustion chamber communicate with each other by a first communication portion; the combustion chamber and the space communicate with each other by a gas-flow hole of the annular partition wall portion; the first communication portion and the inner cylindrical wall portion face each other in the radial direction of the housing; and a combustion product generated in the ignition device chamber passes through the first communication portion, then collides with the inner cylindrical wall portion, changes a flow direction toward the top plate, and passes through the gas-flow hole of the annular partition wall portion.