Knee Airbag Tether Structure for Instrument Panel Conformity
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Solution Overview
Problem
Conventional knee airbags face challenges in effectively deploying and positioning themselves to protect vehicle occupants' legs during collisions, as they often fail to conform to the complex contours of the instrument panel, potentially leading to incomplete deployment and reduced protection.
Innovation Solution
The knee airbag features a tether system with interconnected panels that form inflatable chambers, allowing the cushion portion to bend and conform to the instrument panel's contours, ensuring complete deployment and optimal positioning between the occupant's legs and the panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the knee airbag uses a conventional flat panel structure, then the manufacturing is simple, but the airbag cannot conform to the complex contours of the instrument panel
Solution Approach 1:
The knee airbag is divided into multiple panels (front panel, rear panel, side panels) that are interconnected to form a three-dimensional structure. This segmentation allows each panel to be relatively simple while the overall structure conforms to the complex instrument panel contours through their coordinated arrangement and interconnections.
Solution Approach 2:
The knee airbag transitions from a conventional two-dimensional flat structure to a three-dimensional configuration with depth and volume. The panels are arranged to create a volumetric structure that can wrap around and conform to the curved and angled surfaces of the instrument panel, enabling contour conformity that flat structures cannot achieve.
2Reliability
If the knee airbag uses a simple deployment structure, then the device complexity is low, but the deployment completeness is reduced
Solution Approach 1:
The tether system is pre-configured with specific lengths and attachment points on the panels before deployment. This preliminary arrangement ensures that when the airbag inflates, the tethers automatically tension at the correct moments to guide the panels into their proper positions and create the desired bends, ensuring complete and reliable deployment without requiring complex active control mechanisms.
Solution Approach 2:
The tethers act as intermediary elements that mediate between the inflation pressure and the final panel positioning. During deployment, the tethers transfer and distribute the inflation forces across the panel structure, guiding the formation of bends and ensuring that all panels deploy completely and conform to the instrument panel contours, thereby improving deployment reliability.
3Stability of the object's composition
If the knee airbag panels are interconnected with multiple interior connections, then the structural stability is improved, but the manufacturing complexity increases
Solution Approach 1:
The knee airbag structure is segmented into discrete panels with defined interconnection points. The interior connections are strategically placed at specific locations where structural support is most needed, rather than providing continuous connectivity. This segmented approach maintains structural stability while minimizing the number of connections required, thereby reducing manufacturing complexity.
Solution Approach 2:
The interior connections are distributed non-uniformly across the panel structure, with higher connection density in regions requiring greater structural stability (such as near the front panel and along critical load paths) and lower density in regions where flexibility is more important. This local differentiation optimizes structural stability while minimizing overall manufacturing complexity.
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 tether system enables the knee airbag to follow the instrument panel's contours, ensuring effective deployment and enhanced protection for vehicle occupants by maintaining a close spacing and preventing obstruction, thus improving the overall safety and functionality of the airbag system.
Implementation Method 1
The tether has a length that is shorter than the distance between the locations on the cushion portion to which the tether is connected. The tether is configured to become tensioned in response to inflation of the cushion portion and causing a bend to form in the cushion portion.
Data Source
AI summary
A knee airbag includes a cushion portion, which includes overlying panels interconnected along a perimeter connection to define an inflatable volume of the knee airbag. The panels are interconnected within the perimeter connection along one or more interior connections that define inflatable chambers within the inflatable volume. The knee airbag also includes a tether connected to an exterior surface of the cushion portion at spaced locations. The tether has a length that is shorter than the distance between the locations on the cushion portion to which the tether is connected. The tether is configured to become tensioned in response to inflation of the cushion portion and causing a bend to form in the cushion portion.