Vehicle Knee Airbag Appendage for Lateral Leg Control
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Solution Overview
Problem
Existing vehicle safety systems fail to effectively reduce the force applied to a driver's leg or foot during an impact, as lateral movement of the legs can cause the feet to hit pedals, leading to increased injury risks.
Innovation Solution
A knee airbag with an appendage is deployed beneath the instrument panel, expanding to limit lateral movement of the driver's legs and reduce forces applied to the pedals by expanding in a controlled manner, with the primary and secondary portions of the airbag fluidly connected and vented to manage firmness and timing of deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a traditional airbag is deployed without an appendage, then the airbag can provide basic cushioning, but it fails to effectively limit lateral movement of the driver's legs and reduce forces applied to pedals
Solution Approach 1:
The airbag is divided into a primary portion and a secondary portion (appendage). The primary portion provides general cushioning while the secondary portion specifically targets lateral movement control between the driver's legs. This segmentation allows each part to perform its specialized function, effectively reducing forces on the driver's leg or foot without requiring a completely different airbag design.
Solution Approach 2:
The secondary portion of the airbag extends between the driver's legs in a dimension that addresses lateral movement specifically. By adding this appendage that projects laterally, the airbag system gains the ability to control side-to-side motion in addition to the vertical cushioning provided by the primary portion, thereby reducing harmful forces without significantly increasing overall complexity.
2Speed
If the airbag appendage expands immediately with the primary portion, then deployment is fast, but the firmness and timing control is insufficient to optimize force reduction
Solution Approach 1:
The airbag system uses fluid communication between the primary and secondary portions to dynamically control deployment timing and firmness. The secondary portion can be filled with gas or liquid that allows it to expand at a controlled rate, becoming firmer over time. This dynamic adjustment enables the appendage to provide initial cushioning softness while progressively increasing firmness to effectively limit lateral movement, optimizing both deployment speed and timing control.
Solution Approach 2:
The firmness of the secondary portion is controlled by changing the physical parameters of the gas or liquid used to inflate it. By adjusting the pressure, volume, or composition of the fluid in the secondary portion, the system can optimize the timing and degree of expansion to match the specific safety requirements, thereby achieving reliable firmness control while maintaining fast initial 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 airbag with an appendage significantly reduces the force and shear displacement on the occupant's leg, preventing pedal impact and enhancing safety by mitigating lateral movement and peak forces, as demonstrated by comparative graphs showing reduced tibia indices and shear displacement.
Implementation Method 1
the airbag, along with the appendage, may expand
Implementation Method 2
the primary and secondary portions of the airbag fluidly connected and vented to manage firmness and timing of deployment
Data Source
AI summary
An airbag includes a primary portion and a secondary portion. The primary portion defines a first chamber and the secondary portion defines a second chamber fluidly connected to the first chamber. The primary portion further defines a center axis and the secondary portion is disposed at least partially along the center axis. In its unexpanded state, the airbag may be disposed under an instrument cluster.