Steering Wheel Airbag Venting for Controlled Rim-Cross Deployment
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Solution Overview
Problem
Conventional airbag deployment from the steering wheel hub, especially when electronic devices are positioned above, is inefficient and can cause excessive strain on the vehicle occupant due to the airbag deploying from the rear side of the steering wheel rim, which is not suitable for modern steering wheel designs.
Innovation Solution
The airbag module is positioned beneath the steering wheel rim with a vent opening beneath the rim, a connecting chamber with a smaller volume than the restraint chamber, and a tether mechanism to adjust deployment based on seating position, ensuring the airbag deploys through a clearance between the hub and rim in a controlled manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the airbag module exit opening is positioned beneath the steering wheel rim to accommodate electronic devices on the upper side, then the steering wheel can integrate modern electronics, but the airbag must pass through the steering wheel rim from rear to front which increases deployment aggression and occupant strain
Solution Approach 1:
A vent opening is introduced as an intermediary element in the connecting chamber to allow controlled release of filling gas. This mediator reduces the aggressive deployment force by venting excess gas, thereby protecting the occupant while still allowing the airbag to deploy from the rear-side exit opening position that accommodates electronic devices.
Solution Approach 2:
The vent opening changes the physical parameters of gas flow within the airbag system. By providing an alternative pathway for gas escape, the pressure and flow velocity parameters are modified to reduce deployment aggression while maintaining adequate restraint function.
2Reliability
If the vent opening is positioned beneath the steering wheel rim in the connecting chamber, then the filling gas can escape early and behind the restraint chamber, but the structural complexity of the airbag module increases
Solution Approach 1:
The connecting chamber is designed to serve multiple functions: it connects the gas generator to the restraint chamber, positions the restraint chamber correctly, and provides the vent opening for controlled gas release. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in structural complexity.
3Speed
If the airbag deploys quickly to provide immediate protection, then the restraining effect is improved, but the occupant experiences greater strain particularly in out-of-position situations
Solution Approach 1:
The vent opening provides a partial release pathway for the filling gas, allowing some gas to escape while still permitting sufficient gas to reach the restraint chamber for effective restraint. This partial action approach balances deployment speed with occupant protection, reducing excessive strain while maintaining adequate restraint force.
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 allows for a less aggressive airbag deployment, reducing occupant strain, especially in unusual seating positions, by controlling gas flow and positioning the airbag effectively, thus enhancing safety and adaptability.
Implementation Method 1
a gas generator (24) accommodated in the airbag module (18) and an airbag (26) connected to the gas generator (24) and expandable with filling gas produced by the gas generator (24)
Implementation Method 2
the connecting chamber (34) has at least one vent opening (72) to allow filling gas to flow out of the airbag (26) even before said filling gas reaches the restraint chamber (32)
Data Source
AI summary
A steering wheel (10) includes a steering wheel rim (16) and an airbag module (18) accommodated in a hub region (12) of the steering wheel (10) and comprising an airbag (26), wherein an exit opening of the airbag module (18) is located at a position different from an upper side of the steering wheel (10) and beneath the steering wheel rim (16) and the airbag module (18) is disposed so that the airbag (26) deploys through a clearance (22) between the hub region (12) and the steering wheel rim (16) toward the upper side of the steering wheel (10). The airbag (26) comprises a cushion-type restraint chamber (32) and a connecting chamber (34), wherein the restraint chamber (32) covers, in the completely filled state, the steering wheel rim (16) on the occupant side, while the connecting chamber (34) connects the restraint chamber (32) via an inflation orifice disposed on a rear wall (50) of the restraint chamber (32) to a gas generator accommodated in the airbag module (18), wherein the connecting chamber (34) of the airbag (26) includes at least one vent opening (72) to allow filling gas to flow out of the airbag (26) even before it reaches the restraint chamber (32).