Inflator Flow Control Disc for Two-Stage Gas Separation
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Solution Overview
Problem
Existing two-stage inflators for inflatable vehicle occupant protection devices face difficulties in adjusting the desired flow rate of inflation fluid at certain pressure conditions, which affects the effectiveness of the inflation process.
Innovation Solution
The introduction of a flow control disc within the inflator's secondary filter assembly allows for a two-stage configuration where both stages share a common filter chamber, with the flow control disc maintaining a closed condition to prevent combustion products from entering the secondary stage during primary actuation and opening to permit secondary inflation fluid entry during simultaneous primary and secondary actuation, thereby controlling the flow effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-stage inflator configuration is used with separate filter chambers, then reliability is improved by isolating combustion products, but device complexity increases and flow rate adjustment becomes difficult
Solution Approach 1:
The patent merges the filter chamber to be shared between primary and secondary stages, eliminating the need for separate filter chambers. The flow control disc is positioned within this shared filter chamber to manage combustion product isolation, thereby reducing structural complexity while maintaining protection reliability.
Solution Approach 2:
The flow control disc acts as an intermediary element within the shared filter chamber. It selectively controls the passage of combustion products based on pressure differential, allowing the system to maintain reliability without requiring complex separate filtration systems for each stage.
2Manufacturing precision
If pressure differential control is implemented to manage flow, then flow rate precision is improved, but device complexity increases
Solution Approach 1:
The flow control disc utilizes the natural pressure differential between chambers to automatically regulate flow. When secondary chamber pressure exceeds primary chamber pressure, the disc shifts position to open the flow path, eliminating the need for external actuators or complex control mechanisms while achieving precise flow rate control.
Solution Approach 2:
The system changes the pressure parameter dynamically to control flow. By allowing pressure to build in the secondary chamber and using this pressure differential to move the flow control disc, the system achieves precise flow rate adjustment without adding mechanical complexity.
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 configuration enables precise control of inflation fluid flow, ensuring effective deployment of the protection device by preventing combustion products from interfering with the secondary propellant and allowing supplementary inflation fluid to enter the filter chamber only when both stages are actuated, enhancing the inflator's performance and reliability.
Implementation Method 1
a flow control disc that is configured to separate a flow direction of the secondary inflation fluid into the filter chamber from a flow direction of combustion products into the secondary stage
Implementation Method 2
A second or secondary stage is configured as a secondary source of inflation that can supplement the primary stage
Data Source
Figure 1
Figure 2A~2B
Figure 2C
AI summary
An inflator (40) for inflating an inflatable vehicle occupant protection device includes a primary stage (50) actuatable to produce a primary flow of inflation fluid, a secondary stage (100) actuatable to produce a secondary flow of inflation fluid, and a filter chamber (150) into which the primary and secondary flows of inflation fluid are directed. The inflator (40) also includes a secondary filter assembly (120) that permits the secondary flow of inflation fluid to flow into the filter chamber (150) and blocks particulates from flowing from the filter chamber into the secondary stage (100).