Gas Generator with Heat-Initiated Pyrotechnic Charge
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Solution Overview
Problem
Current gas generators for motor vehicle safety systems, such as airbags, rely on costly and toxic energetic pyrotechnical charges with limited yield, and their decomposition time is incompatible with system requirements.
Innovation Solution
A tubular gas generator with distinct reaction, diffusion, and combustion chambers, where the combustion of a solid pyrotechnical charge is sustained by heat generator means without chemical interaction, using an ammonium nitrate/guanidine nitrate mixture with an equilibrated oxygen balance, allowing for controlled decomposition time and high molar yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional pyrotechnical charges are used, then gas generation capability is achieved, but cost and toxicity increase while yield is limited
Solution Approach 1:
The invention changes the chemical composition parameters of the energetic charge by using an oxidoreducing mixture with equilibrated oxygen balance, specifically employing compounds like ammonium nitrate and organic fuels. This parameter change achieves high gas yield while reducing toxicity compared to conventional pyrotechnical charges, as the decomposition products are less harmful and the oxygen balance optimization ensures complete combustion without excessive oxidizing agents.
2Speed
If fine granulometry charge (10-200 micrometers) is used, then decomposition speed increases, but decomposition time becomes too brief for system requirements
Solution Approach 1:
The invention introduces a dynamic control mechanism through the diffusing gas flow that progressively initiates charge decomposition. Instead of simultaneous decomposition of fine granulometry charge, the system uses a controlled gas flow from a combustion chamber to gradually diffuse through and ignite the charge particles in sequence. This dynamic approach maintains high initial decomposition speed while extending the overall decomposition duration to match system requirements.
3Productivity
If oxidoreducing mixture with equilibrated oxygen balance is used, then gas generation efficiency improves, but decomposition time becomes incompatible with system requirements
Solution Approach 1:
The invention segments the decomposition process into two distinct phases: first, rapid combustion of a pyrotechnical charge in a confined chamber generates initial high-temperature gases; second, these gases diffuse through a controlled pathway to initiate gradual decomposition of the oxidoreducing mixture. This segmentation allows the system to achieve both high gas generation efficiency from the oxidoreducing mixture and adequate decomposition time through the staged initiation process.
4Reliability
If chemical interaction between heat generator means and energetic charge is eliminated, then system reliability improves, but initiation control becomes more difficult
Solution Approach 1:
The invention introduces a diffusing gas flow as an intermediary between the heat generator means and the energetic charge. The combustion products from the pyrotechnical charge serve as the intermediary medium that physically transmits heat and chemically initiates the oxidoreducing mixture through diffusion, rather than direct chemical interaction. This intermediary approach maintains reliable initiation control while ensuring the heat generator means and energetic charge remain chemically independent.
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 solution provides a cost-effective, compact, and efficient gas generation system with controlled decomposition time, reducing toxicity and operational costs while ensuring reliable performance for motor vehicle safety systems.
Implementation Method 1
heat generator means which generate sufficient heat to trigger and sustain combustion of said charge
Implementation Method 2
a second, a so-called 'diffusion' chamber, being able to receive gases generated by the combustion of a solid pyrotechnical charge placed in the first chamber
Data Source
Figure 1~3
Figure 4~5
AI summary
The present invention relates to a gas generator (1) for a safety device for a motor vehicle, which comprises at least two distinct chambers respectively designated as first (2) and second (3) chambers, which communicate with each other through at least one opening or nozzle, the first (2) of these chambers being isolated from the outside, the second one (3) a so-called 'diffusion' chamber being able to receive gases generated by the combustion of a solid pyrotechnical charge (5) placed in the first chamber (2), and to discharge them towards the outside. It is remarkable in that: - said solid charge (5) is a mixture consisting of at least one oxidizing charge and a reducing charge, the oxygen balance of which is equilibrated; - a heat-generating means (6) is provided which generates sufficient heat for triggering and sustaining the combustion of said charge (5), this without any other interaction, notably of the chemical type, between this means (6) and this charge (5).