Knee Airbag Module Upward Deployment Trajectory
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Solution Overview
Problem
Conventional knee airbag modules deployed rearwardly from the dashboard, resulting in higher punch force on occupants and reduced dashboard utility due to occupied storage volume, which limited the space for other components like the glove box.
Innovation Solution
A knee airbag module with a housing that deploys the airbag initially downward and then upwardly, utilizing panels with varying cross-sectional lengths and pleats to optimize deployment trajectory and match perimeters, reducing punch force and enhancing dashboard utility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the knee airbag deploys rearwardly from the dashboard, then the airbag can protect the occupant's knees, but the punch force on the occupant increases and dashboard storage volume is reduced
Solution Approach 1:
The airbag deployment direction is inverted from the conventional rearward deployment to an upward deployment trajectory. The airbag initially deploys downward from the dashboard, then transitions to deploy upward along the dashboard surface, positioning the front panel adjacent to the instrument panel and the rear panel adjacent to the occupant's knees. This inverted deployment path reduces punch force while maintaining protective function.
Solution Approach 2:
The airbag deployment is transformed from a single-dimensional rearward motion to a two-dimensional trajectory involving both downward and upward components. The airbag first deploys downward from the dashboard, then transitions to deploy upward along the dashboard surface, creating a curved deployment path that reduces impact force while maintaining protection.
2Reliability
If the knee airbag deploys rearwardly from the dashboard, then the airbag can protect the occupant's knees, but the dashboard storage volume is reduced
Solution Approach 1:
The airbag deployment direction is inverted from the conventional rearward deployment that occupies dashboard storage space to an upward deployment trajectory that directs the airbag along the dashboard surface toward the instrument panel, thereby preserving dashboard storage volume while maintaining protective function.
3Device complexity
If the front panel has the same cross-sectional vertical length as the rear panel, then the airbag structure is simple, but the airbag cannot deploy upwardly to reduce punch force
Solution Approach 1:
The front panel is designed with a shorter cross-sectional vertical length compared to the rear panel, creating an asymmetric structure. This asymmetry generates a moment that causes the airbag to deploy upwardly during inflation, reducing punch force on the occupant. The asymmetric panel lengths are connected to form an inflatable chamber that naturally transitions from downward to upward deployment.
4Force
If pleats are added to the airbag panels to create asymmetric lengths, then upward deployment is achieved, but the manufacturing complexity increases
Solution Approach 1:
The airbag is segmented into distinct front and rear panels with different cross-sectional vertical lengths. The front panel includes a pleat that creates the length difference, allowing the panels to be manufactured separately and then connected to form the inflatable chamber. This segmentation enables the asymmetric structure to be produced using standard manufacturing processes.
Solution Approach 2:
The cross-sectional vertical length parameter of the front panel is changed by incorporating a pleat, transforming it from a rectangular panel to one with a reduced effective length. This parameter change creates the asymmetric structure needed for upward deployment while using conventional panel manufacturing techniques.
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 airbag module reduces the impact force on occupants and optimizes dashboard space by deploying the airbag in a direction parallel to the legs, minimizing punch force and allowing increased storage volume for other components.
Implementation Method 1
an inflator for providing gas for inflating the airbag
Implementation Method 2
the cross-sectional vertical length of the front panel is shorter than the cross-sectional vertical length of the rear panel thereby causing the airbag to deploy upwardly
Data Source
AI summary
A knee airbag module for protecting a vehicle occupant comprising a housing containing an inflatable airbag and an inflator for providing gas for inflating the airbag; and wherein the airbag is configured to inflate and deploy out of the housing into a position forward of the knees of the occupant; where the airbag includes front and rear panels that are connected together to form an inflatable chamber; wherein when the airbag deploys the front panel is positioned adjacent to an instrument panel of the vehicle and the rear panel is positioned adjacent to the occupant; wherein the cross-sectional vertical length of the front panel is shorter than the cross-sectional vertical length of the rear panel thereby causing the airbag to deploy upwardly.