Knee Airbag Passive Venting for Out-of-Position Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current automotive knee airbag systems do not effectively manage the deployment and inflation to prevent injury to occupants, particularly in cases of out-of-position seating or when the occupant force exceeds a certain threshold, leading to potential submarining and inadequate cushioning.
Innovation Solution
A knee airbag system with a lower portion installation in the instrument panel, featuring a left lobe, right lobe, and central portion, includes vents on the reaction surface that allow gas escape below a threshold occupant force, preventing forceful inflation and providing cushioning by blocking gas escape when the force exceeds the threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the knee airbag inflates forcefully to provide adequate cushioning for proper occupants, then protection against submarining and impact cushioning is improved, but injury risk to out-of-position occupants (such as children standing forward of the seating position) increases
Solution Approach 1:
The patent applies parameter changes by modifying the inflation pressure parameter dynamically. Vents are provided in the airbag structure that allow inflation gas to escape when the occupant force is below a threshold level (out-of-position occupant), resulting in reduced inflation pressure. When the occupant force exceeds the threshold (properly positioned occupant), the vents are blocked and full inflation pressure is achieved, providing adequate cushioning and submarining prevention.
2Device complexity
If the knee airbag structure is simplified without vents, then device complexity is reduced, but the ability to differentiate between proper and improper occupant positioning is lost
Solution Approach 1:
The patent applies self-service by designing the airbag system to automatically detect and respond to different occupant positions without requiring external sensors or complex control systems. The vents are positioned and dimensioned such that they self-regulate based on the force applied by the occupant's knees during inflation, eliminating the need for additional sensing or control mechanisms.
3Object-affected harmful factors
If the vents are positioned to block easily, then out-of-position occupant protection is improved, but the threshold force required for proper occupant cushioning may be too high
Solution Approach 1:
The patent applies local quality by providing vents at specific locations on the airbag structure (e.g., at the periphery or at specific lobes) rather than uniformly distributed vents. This localized vent placement creates different blocking characteristics at different regions of the airbag, allowing the system to achieve the desired threshold force while maintaining effective protection for out-of-position occupants. The local vent configuration optimizes the force threshold based on the expected knee force distribution.
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 system effectively reduces the likelihood of injury by controlling inflation based on occupant size and seating position, ensuring proper cushioning and preventing submarining by adjusting vent functionality in response to occupant force levels.
Implementation Method 1
At least one vent is formed in each of the lobes on the reaction surface to allow inflation gasses to escape from the airbag when, during a crash event, a forwardly-directed force applied to the airbag by the occupant against the lobes is below a threshold level
Implementation Method 2
When the occupant force reaches or exceeds the threshold level, the vents are urged against the instrument panel to substantially block the escape of inflation gasses
Data Source
AI summary
A knee airbag installed in a lower portion of an instrument panel has a deployed condition wherein it extends rearward and upward. The airbag has a left lobe, a right lobe, and a central portion between and joined to the left and right lobes. A vent is formed in the reaction surface of each of the lobes to allow inflation gasses to escape from the airbag when, during a crash event, an occupant force applied forwardly against the lobes is below a threshold level. When the occupant force reaches or exceeds the threshold level, the vents are urged against the instrument panel to substantially block the escape of inflation gasses. The threshold level is selected such that a child-sized occupant standing forward of a desired passenger seating position exerts less than the threshold level.