Airbag Pressure Responsive Vent With Flexible Membrane Tongue
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Solution Overview
Problem
Existing airbag designs face challenges in controlling gas flow during deployment, leading to under-inflation and hot gas impingement on passengers due to inadequate venting, which fails to balance gas restriction and rapid ejection.
Innovation Solution
A flexible membrane is fastened around the airbag's periphery adjacent to the vent, creating a flow passage with a tongue that extends past the vent, allowing controlled gas release away from the passenger, adjustable for pressure and timing, and self-aspirating to prevent vacuum formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vent is provided in the fabric enclosure to allow gas escape, then the maximum pressure within the fabric enclosure is limited and gas can be ejected when the passenger impacts, but the vent cannot restrict outflow sufficiently during deployment to prevent under-inflation while being large enough to allow rapid gas ejection
Solution Approach 1:
The patent employs a dynamic membrane structure that changes its flow control characteristics based on pressure conditions. During deployment, the membrane remains relatively closed to restrict gas outflow and prevent under-inflation. When the passenger impacts and pressure increases, the membrane dynamically opens to allow rapid gas ejection. This dynamic behavior resolves the contradiction by allowing the same structure to provide both restriction and rapid ejection capabilities at different times.
Solution Approach 2:
The membrane structure changes its effective opening area parameter in response to pressure changes. At low pressures during deployment, the effective opening area is small, restricting gas flow. At high pressures during impact, the effective opening area increases dramatically, allowing rapid gas ejection. This parameter change resolves the contradiction between needing small opening for inflation control and large opening for impact venting.
2Reliability
If a vent is provided in the fabric enclosure to allow gas escape, then gas can be ejected when the passenger impacts against the airbag, but hot gas flow from the vent can impinge upon the passenger
Solution Approach 1:
The membrane structure acts as an intermediary between the hot gas and the passenger. It controls the gas flow path and timing, allowing gas to escape in a controlled manner that reduces direct impingement on the passenger. The membrane's selective opening behavior mediates between the need for gas ejection and the need to protect the passenger from hot gas.
Solution Approach 2:
The membrane remains closed during the inflation phase to allow the airbag to fully inflate before the passenger impacts. This preliminary action ensures that the airbag is properly positioned and inflated before gas ejection begins, which helps direct the gas flow away from the passenger and reduces hot gas impingement.
3Speed
If the vent is made larger to allow rapid gas ejection during impact, then compliance is improved, but gas outflow is insufficiently restricted during deployment causing under-inflation
Solution Approach 1:
The membrane provides dynamic flow control where the effective vent area is small during deployment (maintaining inflation pressure) and large during impact (enabling rapid gas ejection). This dynamic adaptation resolves the contradiction between needing small vent area for pressure control and large vent area for rapid ejection.
Solution Approach 2:
The vent operates in two distinct phases: a first phase during deployment where the membrane restricts flow to maintain pressure, and a second phase during impact where the membrane opens to allow rapid ejection. This periodic operation resolves the contradiction by providing different flow characteristics at different times in the airbag lifecycle.
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 solution ensures gradual gas release, preventing under-inflation and directing hot gas away from the passenger, while maintaining airbag integrity and compliance, with adjustable opening pressure and timing for optimal performance.
Implementation Method 1
internal pressure causes the membrane to extend outwardly through the vent
Implementation Method 2
a flexible membrane fastened around part of a periphery thereof to the fabric enclosure adjacent to the vent
Data Source
AI summary
An airbag has a fabric enclosure, a vent in the fabric enclosure, and a flow control device made up of a flexible membrane fastened around part of a periphery thereof to the fabric enclosure adjacent to the vent. The membrane defines a flow passage having a free end through which inflation gas is vented to atmosphere and has a tongue extending away from the free end. The tongue has a pre-deployment position in which it overlies an inner surface of the fabric enclosure and a distal end of the tongue extends past an end of the vent closest to the free end. A first distance from the distal end of the tongue to a closest end of the vent may be shorter than a second distance from the distal end of the tongue to a closest end of fastening between the periphery of the membrane and the fabric enclosure.