Airbag Back Plate Stiffness and Impact Absorption

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Solution Overview

Problem

Conventional vehicle airbag systems experience delayed deployment due to significant deformation of the airbag case during deployment, which reduces deployment performance and can be exacerbated by structural beads intended to increase stiffness.

Innovation Solution

Incorporating a back plate with a stiffness portion that reduces backward deformation of the airbag case, featuring beads extending in the vehicle width direction for increased stiffness and an impact absorber to manage vertical impact loads, allowing for smooth deployment and protection of passengers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the airbag case is made more stiff to reduce deformation during deployment, then deployment speed improves, but the case cannot absorb impact energy from vertical loads

Engineering Contradiction:

Improveairbag deployment speedVSAvoidimpact energy absorption

Core Design Contradiction:

SpeedVSStrength

Solution Approach 1:

The back plate is divided into two distinct functional regions: an upper stiffness portion with beads for reducing case deformation during deployment, and a lower impact absorber portion with folded structures for absorbing vertical impact energy. This segmentation allows each region to optimize its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the back plate are given different structural properties: the upper portion has high stiffness to prevent case deformation, while the lower portion has energy-absorbing characteristics through folded structures. This local differentiation resolves the contradiction by applying the appropriate mechanical property where needed.

Inventive Principle:

Principle #3Local quality

2Strength

If structural beads are added to the airbag case wall to increase stiffness, then deployment performance improves, but the uneven wall surface causes disadvantages to deployment

Engineering Contradiction:

Improveairbag case stiffnessVSAvoiddeployment smoothness

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The stiffness-providing beads are extracted from the airbag case wall itself and relocated to the separate back plate structure. This removes the source of wall unevenness that could interfere with deployment while preserving the stiffness-enhancing function of the beads in their new location on the back plate.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The back plate acts as an intermediary structure between the gas generator and the instrument panel. It provides the necessary stiffness support to the case during deployment without the beads being in direct contact with the airbag, thus preventing deployment interference while maintaining case rigidity.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Loss of energy

If the airbag case is allowed to deform freely during deployment, then impact energy can be absorbed, but deployment is delayed and performance is reduced

Engineering Contradiction:

Improveimpact energy absorptionVSAvoiddeployment time

Core Design Contradiction:

Loss of energyVSLoss of time

Solution Approach 1:

The back plate segments the energy management function: the upper stiffness portion prevents excessive deformation that would delay deployment, while the lower impact absorber portion captures and dissipates impact energy. This temporal and spatial separation resolves the contradiction between rapid deployment and energy absorption.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The stiffness portion of the back plate is positioned to act first during deployment, preventing case deformation before it can occur. The impact absorber then engages subsequently to manage impact energy, creating a preliminary action sequence that prioritizes deployment speed while still providing energy absorption.

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

The back plate's stiffness portion minimizes case deformation, ensuring timely and effective airbag deployment, while the impact absorber absorbs energy from vertical impacts, enhancing passenger safety without increasing system weight or complexity.

Implementation Method 1

a gas generator which generates an airbag inflation gas

Methodology Applied

Scientific EffectGas generation and expansion:

Implementation Method 2

a stiffness portion which reduces deformation of the case toward the back side in the event of deployment of the airbag

Methodology Applied

Scientific EffectStructural stiffness:

Implementation Method 3

an impact absorber to manage vertical impact loads

Methodology Applied

Scientific EffectImpact energy absorption: Impact Force

Data Source

PatentUS8690184B2Vehicle airbag system

Publication Date: 2014.04.08 DAIKYONISHIKAWA CORP

AI summary

A back plate 7 is provided to a backside of a case 8 which accommodates an airbag 11 of an airbag module 5 to reduce the deformation of the case 8 toward a back side in the event of airbag deployment. The back plate 7 is supported on a steering member or the case 8, and an upper portion of the back plate 7 is held on a back support 19 protruding from the instrument panel 1.