Airbag Folding Method Using Moisture and Pressing for Dimensional Stability

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Solution Overview

Problem

Existing methods for folding and fixing airbags in motor vehicle airbag modules face issues with dimensional stability, as the folded shape is either temporary or requires expensive additional fixation methods, leading to potential unfolding during assembly and increased manufacturing costs.

Innovation Solution

A method involving initial folding of the airbag to a larger size, followed by exposure to moisture and subsequent pressing to the intended dimensions, with moisture removal using dry compressed air and negative pressure, enhancing shape retention and allowing for compact storage and assembly without additional aids.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the airbag is folded to a larger size initially and then pressed to the intended dimension after moisture treatment, then dimensional stability is improved, but the process time and complexity increase

Engineering Contradiction:
Improvedimensional stabilityVSAvoidprocess time
Core Design Contradiction:
Stability of the object's compositionVSLoss of time

Solution Approach 1:

The airbag is folded to a larger size initially before pressing, allowing the moisture to penetrate and soften the material in advance. This preliminary folding action enables the subsequent pressing to achieve better dimensional stability as the moistened material is more pliable and conforms better to the mold, reducing the need for repeated adjustments and minimizing overall process time.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent applies moisture to the airbag material, changing its physical parameters (moisture content, flexibility). This parameter change makes the material more pliable during the pressing process, allowing it to be compressed to the intended dimension more effectively and retain that shape better afterward, thus improving dimensional stability without requiring excessive process time.

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If fabric strips are used to pre-fix the airbag, then the airbag remains fixed during assembly, but the cost increases significantly

Engineering Contradiction:
Improvefixation stabilityVSAvoidmanufacturing cost
Core Design Contradiction:
Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The patent replaces the mechanical fixation system (fabric strips) with a moisture-based shaping system. By applying moisture and then pressing the airbag to its intended dimension, the material itself becomes the fixing mechanism through improved dimensional stability. This eliminates the need for additional fabric strips and their associated costs while achieving the same fixation stability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention extracts and eliminates the fabric strip fixation component from the assembly process. Instead of adding external fixation elements, the patent uses the airbag material itself, treated with moisture and pressed to the correct dimension, to maintain its shape without requiring separate fixation components, thereby reducing manufacturing cost.

Inventive Principle:
Principle #2Taking out (Extraction)

3Volume of moving object

If the airbag is pressed to a smaller size with conventional folding methods, then storage space is reduced, but the airbag expands again over time

Engineering Contradiction:
Improvestorage volumeVSAvoidshape retention
Core Design Contradiction:
Volume of moving objectVSStability of the object's composition

Solution Approach 1:

The patent changes the physical parameters of the airbag material by applying moisture before pressing. This moisture treatment increases the material's plasticity and allows it to be compressed to a smaller volume while maintaining that compressed shape. The moistened material forms stronger intermolecular bonds when pressed, enabling it to retain the compressed shape over time without expanding again.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The airbag is folded to a larger size initially before pressing to the final smaller dimension. This preliminary action allows the moisture to penetrate and soften the material, making it more receptive to the pressing process. The result is a compact, stable configuration that maintains its reduced volume without requiring continuous external pressure.

Inventive Principle:
Principle #10Preliminary action

4Stability of the object's composition

If additional fixation aids are used to stabilize the folded airbag, then dimensional stability is maintained, but the device complexity increases

Engineering Contradiction:
Improvefolding stabilityVSAvoidfixation equipment
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent enables the airbag to stabilize itself through moisture treatment and pressing, without requiring external fixation aids. The moistened material, when pressed to the intended dimension, inherently maintains its shape through improved dimensional stability. This self-service approach eliminates the need for complex fixation equipment and additional stabilization components.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention removes the need for additional fixation aids and stabilization equipment from the system. By using moisture treatment and pressing to achieve dimensional stability, the patent extracts the function of fixation from separate components and integrates it into the material treatment process itself, thereby reducing device complexity.

Inventive Principle:
Principle #2Taking out (Extraction)

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 method achieves improved dimensional stability, reducing the need for additional fixation, lowering assembly forces, and enabling more cost-effective manufacturing with reduced risk of visible tear lines and easier handling, allowing for flexible use of the folding station across different airbag modules.

Implementation Method 1

subjecting the gas bag to moisture, pressing the gas bag and simultaneous moisture escaping from the gas bag

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

The removal of the moisture from the gas bag can be further accelerated and intensified by subjecting it to dry compressed air and/or a negative pressure or even a vacuum

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 3

The dry compressed air ensures that the necessary amount of air is available to absorb the moisture

Methodology Applied
Scientific EffectAdvection: Advection

Data Source

PatentEP2454128B1Method for folding a motor vehicle airbag, airbag module and module airbag folding device
Publication Date: 2016.12.21 AUTOLIV DEV AB
  • EP2454128B1 patent drawingFigure 1~2

AI summary

The invention relates to a method for folding an airbag (1) for an airbag module of a motor vehicle, comprising the following steps: folding the airbag (1); applying moisture to the airbag (1); and pressing the airbag (1) and enabling the simultaneous escape of the moisture. The invention further relates to an airbag module and to a device for folding an airbag.