Polyurethane Foam Cushion for Airbag Gas Generator
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Solution Overview
Problem
The gas generators used in inflatable restraint systems, such as airbags, are complex, heavy, and costly due to the need for metallic or ceramic cushions to prevent propellant fracture, which increases manufacturing complexity and weight.
Innovation Solution
A polyurethane-based propellant cushion with a suitable oxidizer is used to prevent propellant movement and fracture, potentially replacing traditional metallic or ceramic cushions, and can be formed as a monolithic grain to simplify the design and reduce weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metallic or ceramic cushions are used to prevent propellant fracture, then propellant protection is improved, but device weight and manufacturing complexity increase
Solution Approach 1:
The cushion material is changed from traditional metallic or ceramic materials to a polymeric foam material. This parameter change in material composition maintains the protective function while significantly reducing the weight of the gas generator assembly.
Solution Approach 2:
The invention uses a polymeric foam cushion that can be formed as a monolithic grain or integrated structure, combining the cushioning function with the propellant holder structure. This composite approach eliminates the need for separate metallic or ceramic cushion components, reducing overall complexity and weight.
2Reliability
If metallic or ceramic cushions are used to prevent propellant fracture, then propellant protection is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The cushion and propellant holder are merged into a single integrated component. The polymeric foam cushion is formed to directly contact and support the propellant grains, eliminating the need for separate metallic or ceramic cushion components and simplifying the overall device structure.
Solution Approach 2:
The polymeric foam cushion is self-forming and can be molded into the final shape directly within the gas generator housing. This self-service characteristic eliminates complex assembly steps required for traditional metallic or ceramic cushions, reducing manufacturing complexity.
3Reliability
If traditional metallic or ceramic cushions are used, then propellant protection is ensured, but manufacturing cost and weight increase
Solution Approach 1:
The manufacturing process is changed from machining or assembling separate metallic/ceramic components to molding a single polymeric foam piece. This parameter change in both material and process significantly simplifies manufacturing while maintaining protective functionality.
Solution Approach 2:
The polymeric foam cushion is self-forming through injection molding or similar processes, where the material is injected into the housing and automatically takes the required shape. This eliminates the need for separate manufacturing and assembly steps required for traditional cushions.
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 polyurethane-based cushion reduces the complexity and weight of the gas generator while maintaining optimal performance by preventing propellant fracture and allowing for a more efficient combustion process, leading to improved gas generation and reduced manufacturing costs.
Implementation Method 1
A polyurethane-based propellant cushion with at least one suitable oxidizer is used to prevent propellant movement and fracture
Implementation Method 2
A polyurethane-based propellant cushion with at least one suitable oxidizer is used to prevent propellant movement and fracture
Implementation Method 3
The initiators are selectively operable to ignite the propellant charges, thereby supplying an inflation gas
Implementation Method 4
The initiators are selectively operable to ignite the propellant charges
Implementation Method 5
The initiators are selectively operable to ignite the propellant charges, thereby supplying an inflation gas
Data Source
AI summary
A gas generator is provided, the gas generator having a propellant cushion that prevents movement of propellant wafers, tablets, or grains by providing a bias thereagainst. Furthermore, the cushion may be formed from a polyurethane-based foam material and if desired, a known oxidizer combined within the foam. Channels inherent within the polyurethane-based foam enhance the combustion of the main gas generant. Alternatively, the substituted polyurethane polymer combined with an oxidizer may be formed as a monolithic grain that provides autoignition and gas generant function in lieu of a primary gas generant or in lieu of an igniter composition, for example.