Composite Tether Yarns for Inflatable Side Curtain Airbags
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Solution Overview
Problem
Conventional inflatable side curtain airbags in vehicles face issues with controlled inflation due to interwoven fabric regions, which can impede gas flow and result in unwanted contraction during inflation, affecting their coverage and effectiveness.
Innovation Solution
The use of composite tether yarns with a strong outer thread and weak core thread, where the outer thread is overfed and twisted around the core, allowing the core thread to break during inflation, enabling the outer thread to unravel and extend the tether length, thus preventing excessive contraction and maintaining an open internal structure for efficient gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the inflatable element is divided into multiple cells by weaving two fabric layers together, then the element volume and gas volume are reduced enabling faster inflation, but the interwoven regions impede gas flow and cause unwanted contraction during inflation
Solution Approach 1:
The inflatable element is divided into multiple cells by weaving two fabric layers together at selected regions, creating discrete compartments that reduce overall element volume and gas volume while enabling faster inflation
Solution Approach 2:
The fabric layers are subjected to pre-stretching or pre-relaxation treatments to adjust their dimensional stability characteristics, and the tether yarns are configured with specific break strengths to control contraction behavior during inflation
2Shape
If tether yarns are used to prevent ballooning, then the inflated shape is controlled, but the two fabric layers contract significantly in the longitudinal direction during inflation
Solution Approach 1:
The fabric layers are pre-stretched or pre-relaxation treated before assembly to anticipate and compensate for the contraction that will occur during inflation, thereby maintaining the intended longitudinal dimensions of the inflated element
Solution Approach 2:
Tether yarns with specific composite constructions are used to interconnect the fabric layers, providing controlled restraint against ballooning while allowing manageable longitudinal contraction through carefully selected yarn properties and configurations
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
This design reduces longitudinal contraction of the inflatable element during inflation, ensuring consistent coverage and effectiveness by allowing the inflatable element to maintain its intended shape and extend its length, thereby enhancing protection in side impacts and rollovers.
Implementation Method 1
the core thread to break during inflation, enabling the outer thread to unravel and extend the tether length
Implementation Method 2
enabling the outer thread to unravel and extend the tether length
Data Source
AI summary
There is disclosed a safety device for a motor vehicle. The device comprises an inflatable (6) element formed from two opposing layers of fabric (10, 11) and the two layers of fabric are interconnected by a plurality of tether yarns (18) extending between said layers. Each said tether yarn (18) is a composite yarn comprising an outer thread (21) and a core thread (20), with the outer thread (21) being overfed on the core thread (20) and having a higher breaking strength than the core thread (23). The device is preferably configured such that the core threads (20) of the tether yarns (18) break (23) upon inflation of said inflatable element (6), thereby permitting the outer thread (21) to unravel and extend the effective length of the tether yarns (18) between said layers.