Inflator Combustible Gas Thermal Conversion Ignition
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Solution Overview
Problem
Existing inflators for vehicle safety systems, such as airbags, face challenges in efficiently generating gas with a combination of solid and compressed gases, often resulting in high temperatures and flow velocities of the discharging gas, which can be undesirable.
Innovation Solution
An inflator design featuring a combustion chamber with a solid propellant and a compressed gas chamber containing an inert gas and a combustible gas at subcritical concentrations, where the combustible gas is thermally converted to facilitate ignition of the solid propellant, using a mixture of argon, oxygen, and hydrogen, with the igniter providing thermal energy to support ignition and gas generation without self-sustaining reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a combustible gas mixture is used in the compressed gas chamber, then the temperature of the discharging gas is increased, but the flow velocity and temperature of the discharging gas become too high which is undesirable
Solution Approach 1:
The patent changes the concentration parameter of the combustible gas in the compressed gas chamber to a subcritical range, preventing self-supporting combustion while still enabling thermal conversion to assist ignition. This parameter adjustment resolves the contradiction by controlling the temperature increase to be beneficial rather than harmful.
Solution Approach 2:
The patent converts the potentially harmful high temperature and flow velocity into a beneficial effect by using controlled thermal conversion of the combustible gas to assist igniter operation. The heat generated from controlled conversion supports the igniter in igniting the solid propellant, transforming what could be a harmful effect into a useful energy source.
2Quantity of substance
If an inert gas is used as compressed gas, then the gas generation amount is increased, but the igniter has to act thermally against the cold inert gas which delays ignition
Solution Approach 1:
The patent introduces a combustible gas as an intermediary substance in the compressed gas chamber. This intermediary undergoes thermal conversion to generate heat that assists the igniter, mediating between the inert gas that provides volume and the need for rapid ignition. The combustible gas acts as a thermal bridge that accelerates the ignition process.
Solution Approach 2:
The patent performs preliminary thermal conversion of the combustible gas to generate heat before the main ignition event. This preliminary action prepares the thermal environment for rapid ignition of the solid propellant, eliminating the delay that would occur with cold inert gas alone.
3Productivity
If the combustible gas concentration is increased to facilitate ignition, then the ignition efficiency is improved, but self-supporting combustion may occur which is undesirable
Solution Approach 1:
The patent precisely controls the concentration parameter of the combustible gas within a subcritical range. This parameter change enables sufficient thermal conversion to support ignition while remaining below the threshold for self-supporting combustion, thus maintaining both high ignition efficiency and system reliability.
Solution Approach 2:
The patent implements a controlled conversion process where the thermal output from combustible gas conversion feeds back to support igniter operation and propellant ignition, but the system is designed with negative feedback mechanisms that prevent runaway self-supporting combustion through careful concentration control.
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 design enhances gas generation efficiency by ensuring complete conversion of the combustible gas while maintaining controlled temperatures, allowing for effective energy assistance in igniting the solid propellant, resulting in a more reliable and efficient gas discharge for vehicle safety systems.
Implementation Method 1
the combustible gas is thermally converted to facilitate ignition of the solid propellant
Implementation Method 2
the heat generated by the conversion of the combustible gas with oxygen supports the igniter in terms of energy
Implementation Method 3
the igniter providing thermal energy to support ignition and gas generation
Data Source
AI summary
An inflator (10), especially for a vehicle safety system, includes a combustion chamber (16) in which a solid propellant (18) combustible under the generation of gas is accommodated, and a compressed gas chamber (24) containing compressed gas (26), wherein even in the non-activated state of the inflator (10) a fluid communication exists between the combustion chamber (16) and the compressed gas chamber (24). The compressed gas (26) contains at least one inert gas as well as oxygen and at least one combustible gas, wherein the combustible gas is provided at a concentration at which no self-supporting conversion of the combustible gas with oxygen takes place.