Gas Generator Stepwise Discharge for Weight Reduction
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Solution Overview
Problem
Current gas generators for air bag systems face challenges in reducing size and weight while maintaining stable gas output performance across varying temperatures and ensuring safety, as well as preventing filter breakage and air bag damage during activation.
Innovation Solution
A disc-type gas generator design with a cylindrical housing featuring multiple groups of gas discharge openings arranged in a specific pattern and shape, including first, second, and third gas discharge openings with distinct opening pressures and shapes, and a sealing tape to control pressure and prevent filter breakage, allowing for stepwise opening to maintain stable combustion and reduce weight and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the housing thickness is reduced to decrease size and weight, then the gas generator becomes smaller and lighter, but the pressure-resistant performance of the housing deteriorates
Solution Approach 1:
The gas discharge openings are segmented into multiple groups with different opening pressures (first, second, and third groups corresponding to first, second, and third opening pressures). This segmentation allows the total gas discharge function to be distributed across multiple openings that open at different pressure thresholds, enabling the housing to withstand lower peak pressures while still achieving the required gas output.
Solution Approach 2:
The system transitions from a static single-opening-pressure design to a dynamic multi-stage opening mechanism. The gas discharge openings progressively open at different pressure levels during the combustion process, allowing the housing to adapt to changing internal pressures and maintain structural integrity with reduced thickness.
2Stress or pressure
If multiple gas discharge openings are provided to reduce housing pressure, then the gas output performance improves, but the filter breakage risk increases due to increased suction force
Solution Approach 1:
Different gas discharge openings are assigned different opening pressures and discharge characteristics based on their specific positions and functions. The first group of openings opens at a lower pressure to prevent excessive pressure buildup, while the second and third groups open at progressively higher pressures to maintain gas output. This local differentiation allows each opening to be optimized for its specific pressure range, preventing filter breakage while maintaining overall system reliability.
3Productivity
If gas discharge openings are opened in unison to reduce pressure, then the gas discharge efficiency improves, but the thrust force becomes unbalanced causing safety issues
Solution Approach 1:
The gas discharge openings are arranged asymmetrically in different groups around the housing, with each group positioned to balance thrust forces. The first, second, and third groups are distributed at specific angular positions, creating a balanced force system that prevents unbalanced thrust even as openings activate at different times. This asymmetric arrangement ensures that the cumulative thrust from progressively opening groups remains balanced.
4Stress or pressure
If the number of gas discharge openings is increased to reduce housing pressure, then the gas output distribution improves, but the manufacturing complexity increases
Solution Approach 1:
Multiple gas discharge openings serve multiple functions simultaneously: they discharge gas at different pressure levels, balance thrust forces through their angular arrangement, and collectively maintain housing pressure within safe limits. Each opening is part of a universal system that achieves pressure control, thrust balance, and gas output regulation through its specific characteristics and position.
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 achieves a reduction in size and weight, stabilizes gas output performance across temperature variations, enhances safety by balancing thrust forces, and minimizes air bag damage by distributing gas discharge evenly, ensuring sustained combustion and efficient air bag deployment.
Implementation Method 1
an igniter therein being ignited in response to power feed through a control unit at the time of collision of a vehicle to thereby burn a gas generating agent with flame caused by the igniter and instantaneously generate a large amount of gas
Data Source
AI summary
A gas generator includes a plurality of gas discharge openings arranged in a circumferential wall portion along a circumferential direction as not overlapping with each other. The plurality of gas discharge openings consist of one group or two or more groups of first gas discharge openings, one group or two or more groups of second discharge openings, and one group or two or more groups of third gas discharge openings. The gas discharge openings included in each of the groups of first to third gas discharge openings are set to be opened at an identical opening pressure. The second gas discharge openings are higher in opening pressure than the first gas discharge openings and lower in opening pressure than the third gas discharge openings. The gas discharge openings included in each group of gas discharge openings are evenly arranged in rotation symmetry at an angle not greater than 120°.