Gas Generating Composition for Vehicle Airbag Inflators
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Solution Overview
Problem
Existing gas generating compositions for vehicle airbag inflators face challenges in reducing combustion temperature without impairing burning rate or gas output, often resulting in increased size and weight, and issues with mist and harmful gas concentration.
Innovation Solution
A gas generating composition with a high content of basic copper carbonate (40-60% by mass) as the oxidizing agent, combined with a fuel such as guanidine nitrate and nitroguanidine, and optionally basic copper nitrate or strontium nitrate, maintains a burning rate above 7.0 mm/sec and gas output above 2.30 mol/100g while keeping the calorific value per mol below 100 kJ/mol, and includes a binder like carboxymethyl cellulose to manage combustion effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If the combustion temperature of the gas generating agent is reduced, then the inflator size and weight can be reduced, but the burning rate and gas output decrease
Solution Approach 1:
The patent changes the chemical composition parameters of the gas generating agent by incorporating specific metal nitrates (copper, zinc, manganese, cobalt, iron, bismuth, molybdenum, or cerium nitrate) in controlled amounts (1-30 mass%). This compositional parameter change allows the system to achieve lower combustion temperature while maintaining adequate burning rate and gas output, resolving the contradiction between inflator size reduction and performance maintenance.
Solution Approach 2:
The patent creates a composite gas generating composition by combining fuel (nitroguanidine, guanidine nitrate, or their mixture) with metal nitrate oxidizers in specific ratios. This composite material approach enables the system to achieve synergistic effects where the metal nitrates provide oxygen for combustion while their specific thermal properties help control combustion temperature, thus reducing inflator size without sacrificing burning rate.
2Quantity of substance
If the amount of gas generating agent is increased, then the gas output can be maintained, but the inflator size and weight increase
Solution Approach 1:
The patent optimizes the calorific value parameter of the gas generating composition by controlling the metal nitrate content and composition. By adjusting this parameter, the system achieves higher gas output per unit mass (improving specific impulse), which allows maintaining required gas output with less total propellant mass, thus reducing inflator weight.
3Temperature
If basic copper carbonate content is increased to reduce calorific value, then the calorific value per mol of generated gas decreases, but the burning rate and gas output are impaired
Solution Approach 1:
The patent precisely controls the content of basic copper carbonate (and other metal nitrates) within specific ranges (1-30 mass% for metal nitrates, with basic copper carbonate at 1-20 mass%). This parameter optimization ensures that enough oxygen is supplied to maintain high burning rate and gas output, while the basic copper carbonate's heat absorption properties effectively control the calorific value per mol of generated gas to 100 kJ/mol or less.
Solution Approach 2:
The patent applies local quality control by using basic copper carbonate specifically for calorific value control while combining it with other metal nitrates that provide oxygen for maintaining burning rate. This differentiated functional assignment within the composite oxidizer system allows simultaneous achievement of low calorific value and high productivity.
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 composition effectively reduces calorific value without compromising burning rate or gas output, minimizing mist and harmful gas generation, thus enabling a smaller, lighter, and safer inflator design for vehicle airbag applications.
Implementation Method 1
A gas generating composition for use in an inflator of a vehicle airbag apparatus and the like, such that a reduction of the calorific value per mol of generated gas is achieved without impairing burning rate or gas output
Implementation Method 2
containing fuel and an oxidizing agent, the oxidizing agent comprising basic copper carbonate
Implementation Method 3
the composition having the content of the basic copper carbonate of more than 40% by mass and 60% by mass or lower, satisfying the following requirements (a) to (c) : (c) the calorific value per mol of the generated gas is 100 kJ/mol or lower
Data Source
AI summary
The present invention is a gas generating composition including fuel and an oxidizing agent, which can be used for an inflator of a vehicle airbag apparatus, wherein the oxidizing agent includes basic copper carbonate, the gas generating composition having the content of the basic copper carbonate of more than 40% by mass and 60% by mass or lower, and satisfying the following requirements (a) to (c): (a) the burning rate is 7.0 mm/sec or above; (b) the gas output is 2.30 mol/100g or above; and (c) the calorific value per mol of generated gas is 100 kJ/mol or lower.