Gas Generator Propellant Cushion for Weight Reduction

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Solution Overview

Problem

Inflatable restraint system gas generators are heavy and complex due to robust construction requirements for pyrotechnic gas generant compounds, leading to increased manufacturing complexity and weight, and there is a need to optimize weight and size while maintaining performance and functionality.

Innovation Solution

A gas generator with a propellant cushion formed from an auto-igniting material, such as a composition containing a polymeric binder, oxidizer, and nitrocellulose, positioned between propellant tablets to prevent fracture and provide auto-ignition, reducing the need for heavy-duty inflator bodies and simplifying manufacturing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a robust inflator body is used to contain pyrotechnic gas generant compounds, then structural strength and reliability are improved, but weight and manufacturing complexity increase

Engineering Contradiction:

Improvestructural strengthVSAvoidinflator weight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

A propellant cushion is positioned between the propellant bed and the closure to prevent fracture of propellant grains during assembly and operation. This cushioning approach allows the use of lighter inflator bodies since the cushion protects the propellant from damage that would otherwise require overly robust containment structures.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The propellant cushion changes the mechanical parameter of pressure distribution between the propellant bed and closure. By providing a compliant interface, the cushion allows the inflator body to be optimized for weight while maintaining sufficient structural strength through the cushion's protective function.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If multiple propellant beds are used for selective activation, then functionality and adaptability are improved, but device complexity and weight increase

Engineering Contradiction:

Improveselective activation capabilityVSAvoidinflator complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The inflator is divided into multiple independent propellant beds that can be selectively activated. Each propellant bed is separated by partitions that allow independent access and ignition, enabling selective activation scenarios while maintaining a relatively simple overall structure through modular segmentation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Partition walls serve as intermediaries between multiple propellant beds, providing both structural separation and pathways for controlled ignition propagation. These partitions enable selective activation functionality while maintaining a unified inflator structure, balancing complexity and adaptability.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If internal partitions are used to fluidly isolate charges, then reliability is improved by preventing sympathetic ignition, but manufacturing complexity and weight increase

Engineering Contradiction:

Improveignition isolationVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Internal partitions divide the inflator into multiple fluidly isolated combustion chambers, preventing sympathetic ignition between propellant beds. The segmented design uses simple cylindrical partitions that can be easily manufactured and assembled, reducing overall manufacturing complexity compared to integrated designs.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The partition walls function as thin film barriers that provide effective fluid isolation for ignition containment. These thin partition structures are easier to manufacture and assemble than thick robust walls, reducing manufacturing complexity while maintaining reliable ignition isolation.

Inventive Principle:

Principle #30Flexible shells and thin films

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 reduces the weight and complexity of gas generators by using a lightweight propellant cushion that ensures reliable auto-ignition and improved performance, allowing for more efficient gas generation and reduced manufacturing costs.

Implementation Method 1

a propellant cushion for biasing a resistance against the propellant bed to prevent fracture of propellant grains

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Implementation Method 2

the cushion is formed from an auto-igniting material thereby providing the requisite auto-ignition of the inflator during a bonfire event

Methodology Applied

Scientific EffectAuto-ignition: Pyrophoricity

Implementation Method 3

provide a gas generator having a propellant cushion that prevents movement of the propellant tablets or grains by providing a bias thereagainst

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Data Source

PatentUS9556078B1Gas generator

Publication Date: 2017.01.31 JOYSON SAFETY SYSTEMS ACQUISITION LLC

AI summary

A gas generator is provided, the gas generator having a propellant cushion that prevents movement of propellant tablets or grains by providing a bias thereagainst. Furthermore, the cushion is formed from an auto-igniting material thereby functioning not only as a cushion, but also as an enhanced auto-ignition charge.