Nested Expanded Metal Filter for Airbag Inflator

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Solution Overview

Problem

The existing airbag inflator filters are bulky and heavy, which affects the overall size and weight of inflatable airbag systems, and they are not effective in preventing incompletely combusted pyrotechnic particles (ICPP) and post-reaction byproducts (PRB) from reaching the airbags, potentially causing improper airbag performance and burn injuries.

Innovation Solution

A filter comprising nested expanded metal layers with specific projections and valleys that nest together, creating a convoluted pathway for gas to exit, which effectively traps ICPP and PRB, reducing their passage to the airbags and improving the combustion efficiency by retaining reactants close to the primary reaction point.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional inflator filters are used, then filtration function is provided, but the volume and mass of the airbag system increase

Engineering Contradiction:

Improvefiltration functionVSAvoidvolume of airbag system

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The filter assembly is positioned within the reaction vessel, nesting the filtration function inside the existing inflator structure. The filter media is contained within a housing that fits into the reaction vessel, eliminating the need for separate external filter components and reducing overall system volume.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The filtration function is merged with the reaction vessel structure. The filter housing is integrated into the reaction vessel, and the filter media is positioned to work in conjunction with the reactant charge, combining multiple functions (reaction containment and particle filtration) into a single integrated assembly.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If traditional inflator filters are used, then filtration function is provided, but the mass of the airbag system increases

Engineering Contradiction:

Improvefiltration functionVSAvoidmass of airbag system

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The filter media consists of a pleated sheet structure that provides large surface area for filtration while maintaining low mass. The thin film structure of the pleated media allows effective particle capture without adding significant weight to the system.

Inventive Principle:

Principle #30Flexible shells and thin films

3Productivity

If reactants are retained close to primary reaction point, then combustion efficiency is improved, but risk of ICPP combustion on airbag surfaces increases

Engineering Contradiction:

Improvecombustion efficiencyVSAvoidICPP combustion on airbag surfaces

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The filter media acts as an intermediary barrier between the reactant charge and the airbag. It allows combustion gases to pass through while intercepting and capturing ICPP, preventing them from reaching and combusting on the airbag surface. The pleated structure provides a large surface area for this intermediary filtration function.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The filter assembly converts the potentially harmful ICPP into a beneficial filtration mechanism. By positioning the filter media within the reaction vessel, ICPP that would otherwise reach the airbag are captured on the filter surfaces, where they are contained and prevented from causing harm to occupants or airbag performance.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 nested filter design reduces the volume and mass of the airbag system, prevents combustion of ICPP on airbag surfaces, minimizes the risk of burn injuries, and enhances the efficiency of reactant conversion to inflation gas, ensuring proper airbag deployment.

Implementation Method 1

A filter comprising nested expanded metal layers with specific projections and valleys that nest together, creating a convoluted pathway for gas to exit, which effectively traps ICPP and PRB

Methodology Applied

Scientific EffectPhysical filtration through nested metal layers: Filter (physical)

Data Source

PatentUS11154802B2Inflator filter for an inflatable airbag system

Publication Date: 2021.10.26 AUTOLIV ASP INC

AI summary

Systems and methods are disclosed for an expanded metal filter for use with an automotive safety device, such an inflatable airbag system. The expanded metal filter is composed of a plurality of expanded metal layers, wherein when a first expanded metal layer is turned over or inverted the peaks of the first expanded metal layer conform to valleys of a second expanded metal layer, and valleys of the first expanded metal layer conform to peaks of the first expanded layer whereby the first and second expanded layers nest together.