Knee-Protecting Airbag Deployment Speed via Folding Sequence
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Solution Overview
Problem
Conventional knee-protecting airbag devices have slow deployment speeds due to multiple deployment stages and lateral folding, which can result in inadequate protection, especially when knees are positioned closer to the front or at higher speeds, and may cause contact with the occupant's legs.
Innovation Solution
The airbag device features a folding and roll-folding structure with a tether system that divides the airbag into chambers, allowing for faster inflation and deployment by unfolding in a primarily vertical direction, with lateral roll-folded portions deploying after the longitudinal roll-folded portion, and a gas circulation structure to enhance deployment speed and symmetry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the airbag is folded using conventional multi-stage folding (folding-in, roll-folding, folding-back), then the airbag can be compactly stored, but the deployment speed becomes slow due to multiple unfolding stages
Solution Approach 1:
The patent extracts and eliminates the folding-back portion from the conventional multi-stage folding process. By removing this unnecessary folding stage, the airbag unfolds in fewer stages during deployment, significantly increasing deployment speed while maintaining compact storage capability through the simplified folding-in and roll-folding stages.
Solution Approach 2:
The patent inverts the conventional folding sequence by emphasizing forward deployment-oriented folding. Instead of folding-back toward the occupant side, the airbag is folded to deploy forward toward the vehicle front, allowing the leading end to reach the knee protection position first and enabling faster deployment.
2Volume of moving object
If the folding-back portions deploy in lateral direction first, then the airbag can be stored compactly, but deployment toward knee position becomes slow and may contact occupant's legs
Solution Approach 1:
The patent applies preliminary action by positioning the leading end of the airbag to deploy forward toward the vehicle front first, before lateral expansion occurs. This ensures the airbag reaches the knee protection position promptly and reliably, preventing contact with the occupant's legs while maintaining compact storage through subsequent lateral deployment.
3Reliability
If the airbag deploys evenly on left and right sides, then occupant safety is improved, but deployment speed may be reduced due to symmetric expansion requirements
Solution Approach 1:
The patent applies dynamics by allowing asymmetric deployment behavior during different phases. In the initial phase, the leading end deploys forward rapidly with minimal lateral constraint. In the subsequent phase, lateral roll-folded portions expand symmetrically to ensure even left-right deployment. This dynamic approach maintains both speed and safety.
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 significantly increases the deployment speed of the airbag to effectively protect the knees by deploying quickly above the knee area, reducing impact and minimizing contact with the instrument panel, thus enhancing occupant protection even in tight spaces or high-speed collisions.
Implementation Method 1
an inflator that supplies gas to the airbag, the knee-protecting airbag device inflating and deploying the airbag from the base end to a position between the vehicle body and the knees of the occupant with the gas from the inflator
Data Source
AI summary
The inflation and deployment speed of an airbag of a knee-protecting airbag device is increased to quickly deploy the airbag to a position where it can protect the knees of the occupant, thereby improving the occupant protection function. An airbag (10), from a state in which it is arranged in a flat form, is folded sequentially through a first step in which a leading end (10S) is tucked and folded into the airbag (10), a second step in which left and right ends (10M) of the airbag (10) are roll-folded toward each other toward a vehicle-body-side base fabric sheet (12) on the vehicle-body side, and a third step in which the leading end side of the airbag (10) in the deploying direction (F) is roll-folded toward the base end (10T) toward the vehicle-body-side base fabric sheet (12). The folded airbag (10) is accommodated in a case together with an inflator (2), and a base end (10T) thereof is fixed to the case. Thus, an airbag device (1) is produced and is attached to a vehicle, at a position in front of the knees of the occupant.