Inflatable TPE Reaction Surface for Non-Circular Steering Wheel Airbag Control
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Solution Overview
Problem
Existing vehicle airbag systems with non-circular steering wheels face challenges in providing an effective reaction surface for airbags during impacts, as traditional circular rims do not adequately support the airbag's inflation and kinematic control.
Innovation Solution
Incorporating an inflatable device made of thermoplastic elastomer, which acts as a reaction surface for the airbag by supporting it during impacts and limiting rotation, and is fluidly isolated from the airbag's inflation chamber, allowing it to extend into the passenger cabin and provide additional support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional circular rim is used as the reaction surface, then the airbag can be supported during inflation, but the airbag rotation cannot be effectively limited and the system is incompatible with non-circular steering wheels
Solution Approach 1:
The patent applies the dynamics principle by making the reaction surface inflatable and deformable. The reaction surface inflates from a deflated state to an inflated state, transforming from a flexible membrane into a rigid structure during deployment. This dynamic transformation allows the reaction surface to adapt to non-circular steering wheel geometries while maintaining reliable airbag kinematic control through its inflated rigid form.
Solution Approach 2:
The patent applies parameter changes by altering the physical state of the reaction surface from deflated (flexible) to inflated (rigid). This parameter change enables the reaction surface to provide consistent geometric support for airbag deployment regardless of the steering wheel shape, resolving the contradiction between adaptability to non-circular wheels and reliability of airbag control.
2Reliability
If the reaction surface is made rigid to provide stable support, then airbag kinematic control is improved, but the device complexity and packaging space increase
Solution Approach 1:
The reaction surface uses a dynamic structure that transitions from flexible to rigid through inflation. This eliminates the need for permanently rigid complex structures, as the rigidity is temporarily created only when needed during airbag deployment, simplifying the overall device design while maintaining support stability.
Solution Approach 2:
The reaction surface is nested within the steering wheel assembly, inflating from a compact deflated state to provide external support. This nesting approach allows the rigid support function to be achieved without adding external complex structures, as the reaction surface is integrated within the existing steering wheel geometry.
3Reliability
If the reaction surface is inflated to provide rigid support, then airbag deployment control is improved, but the inflation medium consumption increases
Solution Approach 1:
The patent segments the inflation system into two separate chambers: a first inflation chamber for the airbag and a second inflation chamber for the reaction surface. This segmentation allows independent control of inflation medium distribution, enabling the reaction surface to be inflated with a dedicated smaller amount of medium only when needed for deployment control, rather than continuously consuming medium.
Solution Approach 2:
The reaction surface inflation operates on a periodic basis only during airbag deployment events, rather than continuously. The inflation medium is supplied to the reaction surface chamber temporarily during impact events, reducing overall consumption compared to continuous inflation systems.
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 inflatable device effectively controls the kinematics of the driver during impacts by acting as a reaction surface, allowing the airbag to function with non-circular steering wheels and providing enhanced protection by extending into the knee area of the passenger cabin.
Implementation Method 1
The inflatable device is a thermoplastic elastomer
Data Source
AI summary
An assembly for a vehicle includes a steering wheel having a hub, an airbag supported by the hub and inflatable to an inflated position, and an inflatable device supported by the hub and inflatable to an inflatable position. The inflatable device defines an inflation chamber. The inflatable device is a thermoplastic elastomer (TPE).