Gas Generator Closure Member Radial Opening Control
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Solution Overview
Problem
Conventional gas generators face issues with the scattering of closure members when activated, which can lead to their fragments being dispersed with inflation gas, posing a risk in air bag inflators and necessitating measures to prevent this scattering.
Innovation Solution
A gas generator design featuring a thin-walled closure member with radially extending breakable portions and a stopper portion on the ceiling wall to restrict the opening angle of door portions to less than 90°, preventing excessive separation and scattering while ensuring combustion gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a closure member is used to close the outlet hole, then combustion gas can be contained in the housing, but the closure member scatters when activated due to large detonation force
Solution Approach 1:
The closure member is divided into multiple door portions (first door portion, second door portion, third door portion) that can open independently. Each door portion is hinged to the outer circumferential wall and can rotate outward when broken, allowing controlled fragmentation that prevents dangerous scattering while maintaining gas containment functionality
Solution Approach 2:
The closure member transitions from a static closed structure to a dynamic multi-state structure. The door portions can rotate outward when activated, changing from a closed state (containing gas) to a partially open state (releasing gas in a controlled manner), accommodating the detonation force dynamically
2Ease of manufacture
If the closure member is made thin-walled, then it can break easily to allow gas flow, but it may separate from the outer circumferential wall and scatter
Solution Approach 1:
The thin-walled closure member is segmented into multiple door portions connected by breakable portions. This segmentation allows the structure to break in a controlled manner into predefined segments rather than scattering randomly, maintaining ease of manufacture while preventing harmful scattering
Solution Approach 2:
The breakable portions are pre-formed at specific locations to ensure controlled breaking behavior. The door portions are pre-positioned with hinges and stopper portions that guide their opening motion, ensuring that when the thin-walled structure breaks, it does so in a predictable pattern that prevents separation from the outer circumferential wall
3Productivity
If door portions are opened radially, then combustion gas can flow out efficiently, but centrifugal force may cause separation from the outer circumferential wall
Solution Approach 1:
The stopper portion is positioned to prevent the door portions from opening beyond a predetermined angle. This preliminary constraint counteracts the centrifugal force that would otherwise cause excessive opening and separation, allowing efficient gas flow within safe limits while preventing detachment
Solution Approach 2:
The opening angle of the door portions is controlled by the stopper portion to optimize the balance between gas flow efficiency and structural integrity. By limiting the opening angle parameter, the design achieves sufficient gas release while preventing the centrifugal force from causing separation
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 effectively prevents the scattering of closure member fragments, allowing for efficient combustion gas flow without the need for additional filters, reducing inflator weight and enabling adjustable output properties.
Implementation Method 1
gas generating agents which generate gas when combusting and a squib accommodated within the housing for igniting the gas generating agents
Implementation Method 2
thin breakable portions, which are breakable when the squib is activated... portions of the closure member which lie between the breakable portions are individually made to open as door portions radially about positions in the vicinity of the outer circumferential wall by the breakable portions being broken when the squib is activated
Implementation Method 3
a stopper portion is formed on a surface of the ceiling wall which lies on the closure member so as to restrict the opening of the door portions so that an angle at which the door portions are opened becomes less than 90°
Data Source
AI summary
In a gas generator of the invention, a closure member is disposed so as to be connected to an outer circumferential wall side along a circumferential edge thereof in a housing and to close an outlet port which is formed in a ceiling wall of the housing. Thin breakable portions adapted to be broken when a squib is activated are formed in the closure member so as to extend substantially radially from a center of the closure member in a rectilinear fashion. When the squib 19 is activated, the breakable portions are broken, whereby portions of the closure member 11 which lie between the breakable portions are individually made to be opened radially. A stopper portion is formed on a closure member side surface of the ceiling wall such that the opened door portions are brought into abutment therewith so that the opening angles of the door portions become less than 90° while ensuring an angle at which combustion gas is allowed to flow out.