Knee Airbag Bracket Segmentation for Rigidity and Weight
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Solution Overview
Problem
Existing knee-airbag device attachment structures in vehicles face a trade-off between achieving sufficient rigidity for airbag inflation and minimizing vehicle weight, as increasing rigidity through thicker or higher-rigidity support members can deteriorate fuel economy.
Innovation Solution
A knee-airbag-device attachment structure that uses short, high-rigidity vehicle-body side brackets and instrument-panel-member supporting-post side brackets, with plate-shaped portions positioned perpendicularly to the vehicle longitudinal direction, to disperse the airbag inflation load to the vehicle body, thereby maintaining support rigidity while minimizing weight increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the plate thickness of the support member is increased or high-rigidity members are used to increase the rigidity of the attachment structure, then the support rigidity during airbag inflation is improved, but the vehicle weight increases which deteriorates fuel economy
Solution Approach 1:
The attachment structure is divided into two separate brackets: a vehicle-body side bracket that connects the knee-airbag device to the vehicle body, and an instrument-panel-member supporting-post side bracket that connects the device to the instrument panel supporting post. This segmentation allows each bracket to be optimized independently for rigidity and weight.
Solution Approach 2:
The vehicle-body side bracket is designed with locally increased rigidity at critical connection points while maintaining shorter overall length. The bracket connects to the vehicle body at positions that provide optimal structural support, allowing high-rigidity materials or thicker plates to be used only where necessary rather than throughout the entire bracket.
2Strength
If the length of the support member is increased to improve support rigidity, then the structural stability is improved, but the weight of the attachment structure increases
Solution Approach 1:
The support function is segmented between two brackets of moderate length rather than one long bracket. The vehicle-body side bracket spans from the knee-airbag device to the vehicle body, while the instrument-panel-member supporting-post side bracket spans from the device to the supporting post, collectively providing the necessary support rigidity with shorter individual components.
3Strength
If high-rigidity materials are used for the support member, then the support rigidity during inflation is improved, but the manufacturing cost and vehicle weight increase
Solution Approach 1:
High-rigidity materials or thicker plate sections are used only at critical locations in the vehicle-body side bracket where maximum structural support is needed, while other portions of the bracket use standard materials. This localized application of high-rigidity materials maintains necessary support rigidity during airbag inflation while reducing overall material cost and weight compared to using high-rigidity materials throughout the entire structure.
Data Source
AI summary
A knee-airbag-device attachment structure comprises knee-airbag devices and vehicle-body side brackets which connect the knee-airbag devices and hinge pillars of a vehicle body, respectively. This knee-airbag-device attachment structure further comprises an instrument-panel-member supporting-post side bracket which connects the knee-airbag device to an instrument-panel-member supporting post which is provided to extend between an instrument panel member and a tunnel portion of a floor panel.