Air-bag Compression via Adiabatic Heating and Valve Control

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Solution Overview

Problem

Current air-bag folding techniques face challenges in minimizing the volume of air-bag modules without compromising deployment characteristics, often resulting in increased forces that can distort the housing due to the elastic nature of air-bag materials and trapped gases, and existing methods are inefficient with long cycle times and large heating/cooling devices.

Innovation Solution

A compression apparatus with a device having a cavity that uses a multi-stage compression arrangement and a selectively openable valve to reduce volume through adiabatic heating, allowing gas flow when temperature and pressure reach a predetermined level, and optionally adding phase-change materials for cooling, to efficiently compress air-bag cushions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If high compressive forces are applied to fold the air-bag tightly, then the volume of the air-bag module is reduced, but large forces are generated that may distort or deform the housing

Engineering Contradiction:
Improvevolume of air-bag moduleVSAvoidoutward forces from folded air-bag
Core Design Contradiction:
Volume of moving objectVSForce

Solution Approach 1:

The patent changes the temperature parameter of the air-bag material to alter its mechanical properties. By heating the air-bag to elevated temperatures (e.g., 80-150°C), the material becomes more pliable and easier to compress into tight folds. After folding at elevated temperature, the air-bag is cooled while maintaining compression, which increases the material's stiffness and allows it to hold the folded shape with minimal outward force, thus resolving the contradiction between achieving small volume and avoiding housing deformation.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If heating and cooling techniques are used to fold air-bag cushions, then the compression effectiveness is improved, but the cycle time increases to around two hours

Engineering Contradiction:
Improvecompression effectivenessVSAvoidcycle time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent replaces the conventional slow thermal diffusion heating method with a rapid heating system that uses dielectric heating or microwave heating to heat the air-bag material quickly and uniformly throughout its thickness. This allows the heating step to be completed in minutes rather than hours. The system also uses rapid cooling methods such as forced convection or conduction cooling to quickly reduce the temperature while maintaining compression, thereby dramatically reducing the overall cycle time while preserving compression effectiveness.

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

3Volume of moving object

If the air-bag is compressed tightly into small volume, then the space occupied in the vehicle is minimized, but the deployment characteristics may be compromised

Engineering Contradiction:
Improvespace occupied by air-bag moduleVSAvoiddeployment characteristics
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The patent applies preliminary folding actions to the air-bag while the material is in a softened, heated state. The air-bag is pre-folded into compact configurations (such as accordion folds or random loose folds) at elevated temperature when the material is more compliant. After folding, the air-bag is cooled and compressed while maintaining the folded shape. This preliminary folding at favorable material conditions allows the air-bag to achieve compact volume while preserving its structural integrity and deployment characteristics, as the folding is done before the material stiffens.

Inventive Principle:
Principle #10Preliminary action

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 allows for rapid and efficient compression of air-bag cushions, reducing volume by up to 1/5 to 1/15 of the initial volume, while maintaining the air-bag in a compressed state for longer, and significantly reduces energy consumption and cycle time compared to existing methods.

Implementation Method 1

A compression apparatus with a device having a cavity that uses a multi-stage compression arrangement and a selectively openable valve to reduce volume through adiabatic heating

Methodology Applied
Scientific EffectAdiabatic heating: Adiabatic Heating

Implementation Method 2

optionally adding phase-change materials for cooling

Methodology Applied
Scientific EffectPhase change: Phase Change

Data Source

PatentEP3446932B1Improvements in or relating to air-bag folding
Publication Date: 2019.12.18 AUTOLIV DEV AB
  • EP3446932B1 patent drawingFigure 1a~1b
  • EP3446932B1 patent drawingFigure 2a~2c

AI summary

A compression apparatus comprising: a device having an internal cavity into which a vehicle air-bag may be placed; a compression arrangement operable to reduce the volume of the cavity; a selectively openable valve having a closed position, in which the cavity is sealed in a gas-tight or substantially gas-tight manner, and an open position, in which a gas flow path is opened, allowing communication between the cavity and a further region; and a valve control arrangement operable to place the valve in the closed position during an initial compression, and operable to place the valve in the open position when the temperature and/or pressure within the cavity reaches a predetermined level.