Airbag Gas Generant Composition for Low Flame Temperature Burn Control
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Solution Overview
Problem
Current airbag gas generant formulations face challenges in achieving a high enough burning rate while maintaining low flame temperature and burn rate slope to inflate airbags effectively in side impact applications, as reducing potassium perchlorate to lower flame temperature also reduces the burning rate, leading to issues with airborne particulates and system efficiency.
Innovation Solution
A gas generant formulation comprising guanidine nitrate as the primary fuel, basic copper nitrate as the primary oxidizer, melamine nitrate as the secondary fuel, and potassium perchlorate as the secondary oxidizer, with additives like metal oxides or lubricants to control flame temperature and improve slagging, allowing for a burn rate of at least 50 mm/sec at 40 MPa and a burn rate slope of 0.40 or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the amount of potassium perchlorate is reduced to lower flame temperature, then flame temperature is reduced and system weight is reduced, but burning rate decreases below useful levels
Solution Approach 1:
The patent changes the chemical composition parameters of the gas generant by introducing melamine nitrate as a secondary fuel and basic copper nitrate as a primary oxidizer, replacing part of the traditional potassium perchlorate system. This parameter change allows achieving lower flame temperatures (1800K-1950K) while maintaining adequate burning rates through the synergistic combustion characteristics of the new compositional parameters.
Solution Approach 2:
The patent creates a composite gas generant formulation combining multiple fuel components (guanidine nitrate, melamine nitrate) and oxidizer components (basic copper nitrate, potassium perchlorate) in specific ratios. This composite material approach enables the system to achieve both low flame temperature and sufficient burning rate by leveraging the complementary combustion properties of each component, resolving the contradiction between temperature reduction and burning rate maintenance.
2Productivity
If potassium perchlorate is used to achieve high burning rate, then burning rate increases, but flame temperature becomes too high causing thermal damage
Solution Approach 1:
The patent modifies the chemical composition parameters by incorporating melamine nitrate (1-10% by weight) and basic copper nitrate (25-50% by weight) to replace a portion of the potassium perchlorate system. This parameter modification achieves the dual objective of maintaining high burning rate (≥50 mm/sec at 40 MPa) while controlling flame temperature within the safe range of 1800K-1950K, thereby preventing thermal damage to the airbag cushion.
3Temperature
If amount of potassium perchlorate is reduced to cool flame, then flame temperature decreases, but amount of airborne particulates increases
Solution Approach 1:
The patent changes the compositional parameters by introducing melamine nitrate and basic copper nitrate, which alter the combustion chemistry to produce fewer condensable gases. The specific weight ratios of these components (melamine nitrate: 1-10%, basic copper nitrate: 25-50%) are optimized to minimize potassium chloride condensation while maintaining low flame temperature, thereby reducing airborne particulate generation.
4Object-affected harmful factors
If burn rate slope is reduced for safer airbag deployment, then airbag safety improves, but inflation time increases
Solution Approach 1:
The patent optimizes the compositional parameters of the gas generant, specifically controlling the burn rate slope to be ≤0.40 while maintaining burn rate ≥50 mm/sec at 40 MPa. The formulated composition with melamine nitrate (1-10%), basic copper nitrate (25-50%), and potassium perchlorate (1-10%) achieves this parameter balance, ensuring gradual pressure rise for safety while maintaining rapid enough inflation for effective side impact protection.
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 formulation achieves a high gas output at low flame temperatures, reducing system weight and cost by maintaining a sufficient burning rate and slope, thus meeting performance criteria for side impact airbags while minimizing airborne particulates and thermal damage.
Implementation Method 1
Gas generant formulations that can burn with desirable ballistic performance characteristics at a low flame temperature
Implementation Method 2
The heat sink in the inflator is typically in the form of a metal screen pack which also serves to filter solid combustion residue from the gas stream
Implementation Method 3
The heat sink in the inflator is typically in the form of a metal screen pack which also serves to filter solid combustion residue from the gas stream
Data Source
AI summary
A gas generant formulation for a side impact airbag that includes a primary fuel, a primary oxidizer, a secondary fuel, and a secondary oxidizer. The secondary fuel includes at least melamine nitrate in an amount that is in a range of about 1.00% by weight to about 10.00% by weight. The secondary oxidizer includes at least potassium perchlorate that is in an amount that is in a range of about 1.00% by weight to about 10.00% by weight. The formulation provides a burn rate that is at least 50 mm/sec at 40 MPa and a burn rate slope that is equal to or less than 0.40.