Lightweight Polymeric Gas Generator Frame

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Solution Overview

Problem

Hybrid gas generators are bulkier and heavier than pyrotechnic gas generators due to the need for a reinforced frame to store and contain high-pressure gases, making them costly and inefficient in weight-sensitive applications like automotive and aeronautics.

Innovation Solution

A pyrotechnic gas generator with a lightweight, polymeric frame that uses a secondary chamber with lightened walls made of gas-tight solid polymeric materials, which retain integrity under extreme conditions, allowing for efficient and secure operation by directing energetic combustion products to decompose a secondary compound, thereby regulating gas release and reducing material costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a reinforced frame is used to store and contain high-pressure gases, then the gas generator can store gas under pressure, but the frame becomes heavier and bulkier

Engineering Contradiction:
Improvegas containment capabilityVSAvoidframe weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent changes the material parameters of the frame from traditional metallic materials to polymeric materials, specifically using a polyamide matrix with glass fiber reinforcement. This material substitution maintains the necessary mechanical strength and gas containment capability while significantly reducing the weight and volume of the frame structure.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite materials consisting of a polyamide matrix reinforced with glass fibers. This composite structure provides the necessary mechanical strength, thermal resistance, and gas containment properties while achieving weight reduction compared to traditional metallic frames. The composite material allows the frame to withstand high-pressure gas storage without requiring excessive reinforcement.

Inventive Principle:
Principle #40Composite materials

2Strength

If a reinforced frame is used to resist overpressure from combustion reactions, then the generator can contain combustion products, but the frame becomes heavier

Engineering Contradiction:
Improvepressure resistanceVSAvoidframe weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent modifies the material parameters by selecting a polyamide matrix with specific thermal and mechanical properties, combined with glass fiber reinforcement. This material combination provides sufficient strength to resist overpressure from combustion reactions while maintaining lower weight. The material parameters are optimized to balance pressure resistance, thermal stability, and weight reduction.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The composite structure of polyamide matrix with glass fiber reinforcement provides enhanced mechanical strength and pressure resistance. The glass fibers distributed within the polyamide matrix create a reinforced structure capable of withstanding combustion overpressure while keeping the overall frame weight lower than traditional metallic constructions.

Inventive Principle:
Principle #40Composite materials

3Weight of moving object

If polymeric material is used for the frame, then the weight is reduced, but the material must withstand high temperatures and pressures

Engineering Contradiction:
Improveframe weightVSAvoidthermal and pressure resistance
Core Design Contradiction:
Weight of moving objectVSReliability

Solution Approach 1:

The patent uses a composite material system where a polyamide matrix is reinforced with glass fibers. The polyamide provides the base structural properties and chemical resistance, while the glass fiber reinforcement enhances the thermal stability, mechanical strength, and pressure resistance. This composite approach allows the frame to withstand high temperatures and pressures generated during combustion while maintaining the weight advantages of polymeric materials.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent optimizes the material parameters by selecting specific polyamide formulations and glass fiber characteristics. The material parameters are adjusted to achieve the necessary thermal resistance, pressure withstand capability, and mechanical strength while preserving the weight reduction benefits. The composite structure allows the polymeric frame to operate reliably under extreme combustion conditions.

Inventive Principle:
Principle #35Parameter changes

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 lightweight polymeric frame maintains structural integrity and ensures efficient operation, reducing weight and manufacturing costs while enhancing safety by automatically neutralizing the generator in case of fire, allowing for more flexible design and integration in various applications.

Implementation Method 1

The polymeric material(s) form a matrix in which are dispersed the reinforcing filler and have a decomposition temperature greater than 200° C.

Methodology Applied
Scientific EffectThermal resistance: Thermal Insulation

Implementation Method 2

directing energetic combustion products to decompose a secondary compound

Methodology Applied
Scientific EffectDecomposition: Pyrolysis

Implementation Method 3

The polymeric material(s) form a matrix in which are dispersed the reinforcing filler

Methodology Applied
Scientific EffectComposite reinforcement: Composite Materials

Data Source

PatentEP2079978B1Gas generator
Publication Date: 2015.08.12 TRW AIRBAG SYSTEMS GMBH
  • EP2079978B1 patent drawingFigure 1~2
  • EP2079978B1 patent drawingFigure 3~4
  • EP2079978B1 patent drawingFigure 5~6

AI summary

The invention relates to a gas generator comprising a resistant frame capable of maintaining its integrity during the operation thereof, wherein said frame defines a primary chamber (3) containing a primary pyrotechnical compound such as a propellant, a secondary chamber (14) containing a secondary compound such as ammonium nitrate with an additive, and a stabilisation area (22). The frame portion defining the secondary chamber comprises at least one wall (15, 16) that is made lighter using at least one gas-tight solid polymeric material, said polymeric material(s) being used for forming a lighter wall having a mechanical-property decay temperature higher than 120°C and having mechanical characteristics such that the secondary chamber has an inner volume during operation lower than four times said inner volume under rest conditions.