Retractable Piston Igniter for Uniform Gas Flow
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Solution Overview
Problem
Existing airbag inflator designs using mechanical pistons for seal rupture can cause erratic gas release and obstruction in diffuser passages, leading to non-uniform gas flow and thrust effects, making the inflator bulky and inefficient.
Innovation Solution
The design incorporates a retractable piston with a decreasing diameter impact portion and a hollow venting sleeve that breaks a frangible closure, allowing controlled gas release and retracting back into the igniter housing without obstructing gas flow, enabling higher pressure use and more efficient gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical piston is used to break the seal, then reliability is improved, but gas flow uniformity deteriorates due to obstruction in diffuser passages
Solution Approach 1:
The piston is designed to be retractable rather than stationary. After breaking the seal, the piston automatically retracts into the igniter housing under spring force, dynamically changing its position from blocking to non-blocking. This resolves the contradiction by maintaining reliability during seal breaking while eliminating gas flow obstruction afterward.
Solution Approach 2:
The piston's function is segmented into two distinct phases: seal-breaking mode and retracted mode. The spring mechanism enables the piston to transition between these phases, separating the reliability-critical seal-breaking function from the gas flow-critical diffuser passage clearance.
2Stability of the object's composition
If the diffuser is positioned on a side or far end to avoid obstruction, then gas flow uniformity is improved, but inflator size increases
Solution Approach 1:
Instead of relocating the diffuser to maintain gas flow uniformity, the invention uses a dynamic piston that retracts after seal breaking. This allows the diffuser to remain in its optimal position for gas flow while the piston clears the passage afterward, avoiding the need to increase inflator size.
Solution Approach 2:
The piston system is self-managing through the spring mechanism. After performing its seal-breaking function, the piston automatically retracts without external intervention, clearing the diffuser passage and enabling uniform gas flow without requiring additional space or complex positioning mechanisms.
3Productivity
If higher pressures are used to improve efficiency, then productivity is improved, but safety risks increase due to uncontrolled gas release
Solution Approach 1:
The frangible seal acts as an intermediary between the high-pressure gas and the external environment. It contains the pressurized gas until activation, then fails in a controlled manner to release gas through the diffuser. This mediator enables high-pressure operation for efficiency while preventing uncontrolled release through its controlled failure mechanism.
Solution Approach 2:
The system transitions from a static sealed state to a dynamic controlled release state. The retractable piston and frangible seal work together to control the timing and manner of gas release, enabling safe operation at higher pressures by dynamically managing the pressure containment and release process.
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 solution ensures reliable and uniform gas flow without obstructing diffuser openings, allowing for higher pressure operation with less expensive gases and a more compact inflator design.
Implementation Method 1
a squib electrically actuated and fitted in an end of the igniter housing... Upon actuation of the squib, the retractable piston propels impacting and breaking the frangible closure
Implementation Method 2
the retractable piston propels impacting and breaking the frangible closure releasing gases
Implementation Method 3
The sleeve has one or more, preferably two, vent holes to release the gas pressure generated by the squib
Data Source
AI summary
The present invention inflator (10) has an inflator housing (12), a diffuser (30), a frangible closure (40) and an igniter assembly (20). The igniter assembly (20) has an igniter housing (22), a squib (60) electrically actuated and fitted in an end of the igniter housing (22) and a retractable piston (50) affixed to the igniter housing (22). Upon actuation of the squib (60), the retractable piston (50) propels forward breaking the frangible closure (40) releasing gases pushing the piston (50) retractably back into or over the igniter housing (22) as the pressurized gas releases out of the diffuser (30).