Knee Airbag Deployment Flap for Uniform Lateral-First Inflation
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Solution Overview
Problem
Knee airbags in vehicles deploy unevenly due to limited space in the instrument panel, causing the central portion to deploy ahead of lateral portions, potentially moving the occupant's knees apart.
Innovation Solution
A deployment flap is integrated into the knee airbag module to initially inhibit the central portion's deployment while allowing lateral portions to deploy first, ensuring uniform deployment across the width by rupturing at a controlled time to release the central portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the knee airbag is deployed without restriction, then the central portion deploys ahead of the lateral portions, but this causes the central portion to reach the occupant before the lateral portions and engage the knees/legs causing them to move laterally away from each other
Solution Approach 1:
The deployment flap is positioned to preliminarily block the central portion of the knee airbag before deployment. This preliminary action prevents the central portion from deploying ahead of the lateral portions, allowing the lateral portions to reach the occupant first and establish proper positioning before the central portion is released by the rupturable connection
Solution Approach 2:
The deployment flap is divided into a non-rupturable portion and a rupturable connection, creating segmented control over different portions of the airbag. The non-rupturable portion maintains continuous blocking of the central portion, while the rupturable connection allows controlled release after the lateral portions have deployed, achieving uniform deployment across the airbag width
2Volume of moving object
If the knee airbag module has a compact design due to limited space, then the width of the module is narrower than the width of the deployed knee airbag, but this causes the central portion to deploy along a normal trajectory while lateral portions deploy along oblique trajectories
Solution Approach 1:
The deployment flap preliminarily blocks the central portion to delay its deployment, allowing the lateral portions to deploy along their oblique trajectories first. This preliminary blocking action compensates for the trajectory differences caused by the compact module design, ensuring that all portions of the airbag reach the occupant uniformly despite the narrow module width
Solution Approach 2:
The deployment flap is positioned asymmetrically to span across the opening and block the central portion specifically, while leaving the lateral portions free to deploy along their natural oblique trajectories. This asymmetric blocking strategy accommodates the different deployment paths caused by the compact module geometry while achieving uniform overall deployment
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 deployment flap ensures that the central and lateral portions of the knee airbag deploy simultaneously, enhancing occupant protection by preventing the central portion from deploying ahead of the lateral portions and maintaining uniformity in the deployment process.
Implementation Method 1
The deployment flap is configured to initially inhibit deployment of the central portion of the knee airbag while remaining portions of the knee airbag initially deploy. The deployment flap is configured to thereafter rupture and permit deployment of the central portion.
Data Source
AI summary
A knee airbag module includes an inflatable knee airbag, an inflator for inflating the knee airbag, a housing for supporting the knee airbag and inflator, a cover for enclosing the knee airbag in the housing, and a deployment flap positioned beneath the cover. The housing includes an opening through which the knee airbag deploys. The deployment flap is connected to the housing and spans across at least a portion of the opening. The knee airbag has a width that extends laterally beyond the lateral extent of the housing when the airbag is deployed. The knee airbag also includes a central portion that spans the width of the housing when the knee airbag is deployed. The deployment flap is configured to initially inhibit deployment of the central portion of the knee airbag while remaining portions of the knee airbag initially deploy. The deployment flap is configured to thereafter rupture and permit deployment of the central portion.