Vehicle Seat Airbag Tether Geometry for Occupant Kinematics Control
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Solution Overview
Problem
Current vehicle airbag systems do not effectively control the kinematics of occupants during impacts, particularly in limiting the movement of the airbag panels and optimizing reaction pressure to enhance occupant safety.
Innovation Solution
The airbag assembly includes a tether within the inflation chamber that separates it into top and bottom portions, limiting the movement of the inboard and outboard panels and increasing reaction pressure by controlling the volume of the inflation chamber, thereby enhancing the airbag's ability to manage occupant kinematics during impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the airbag is inflated without a tether, then the inflation chamber has larger volume allowing greater expansion, but the airbag panels move excessively and reaction pressure is insufficient to control occupant kinematics effectively
Solution Approach 1:
The inflation chamber is segmented into top and bottom portions by the tether, which divides the internal volume and creates distinct pressure zones. This segmentation allows the airbag to maintain overall inflation while controlling panel movement through the tether's structural division of the chamber.
Solution Approach 2:
The tether modifies the physical parameters of the inflation chamber by reducing the available volume and increasing the pressure density. By changing the volume parameter through tether deployment, the system achieves higher reaction pressure without requiring a larger overall airbag size.
2Reliability
If the tether is deployed to limit airbag panel movement, then reaction pressure increases and panel control improves, but the device complexity increases
Solution Approach 1:
The tether is designed to deploy automatically upon airbag inflation without requiring external actuation systems. The tether's deployment is self-activating through the inflation pressure itself, eliminating the need for additional sensors, motors, or control mechanisms while achieving reliable panel movement limitation.
Solution Approach 2:
The tether is constructed as a flexible yet structurally rigid element that can be integrated into the airbag assembly without adding significant bulk or complexity. Its thin-film construction allows it to be stored compactly within the airbag and deploy smoothly during inflation, maintaining reliability while minimizing added complexity.
3Stress or pressure
If the tether limits the volume of the inflation chamber, then reaction pressure increases, but the airbag's ability to absorb impact energy is reduced
Solution Approach 1:
The tether segments the inflation chamber into top and bottom portions, creating a pressure-distribution system rather than uniformly reducing volume. This segmentation allows different zones to serve different functions: the constrained zone generates reaction pressure while the overall airbag structure maintains energy absorption capacity through controlled deformation in less-constrained areas.
Solution Approach 2:
The tether applies local volume constraint specifically where panel movement control is needed, rather than uniformly restricting the entire inflation chamber. This localized quality change allows high reaction pressure at the tether interface while preserving energy absorption capacity in other regions of the airbag through gradual deformation.
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 tethered airbag system effectively limits the movement of the airbag panels, increasing reaction pressure and improving the control of occupant kinematics, thereby enhancing safety by optimizing the inflation medium distribution and reaction force during impacts.
Implementation Method 1
The tether is fixed to the inboard panel and the outboard panel between a front edge of the tether and a rear edge of the tether. The front edge of the tether defines a first width, and the rear edge of the tether defines a second width that is less than the first width.
Data Source
AI summary
An assembly includes a seat back having a top end and a bottom end. The assembly includes an airbag supported by the seat back at the top end. The airbag is inflatable to an inflated position that extends forward and upward from the top end of the seat back. The airbag in the inflated position has an inboard panel and outboard panel that define an inflation chamber therebetween. The assembly includes a tether in the inflation chamber, the tether fixed to the inboard panel and the outboard panel between a front edge of the tether and a rear edge of the tether. The front edge of the tether defines a first width and the rear edge of the tether defines a second width that is less than the first width.