Airbag Mounting Device Load Distribution
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Solution Overview
Problem
Modern vehicle seat frames, designed to minimize weight and cost, often compromise structural integrity, leading to inadequate load distribution from airbag modules to the seat frame, resulting in excessive stress on localized areas during deployment.
Innovation Solution
A mounting device with a load transfer device that distributes the load from the airbag module to the seat frame over a larger area by engaging both the outside and inside surfaces of the seat frame, reducing stress concentration and increasing the restraint capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a mounting bracket with studs and nuts is used to couple the airbag module to the seat frame, then the airbag module can be securely mounted, but the clamping load is limited by the size of the studs and nuts, resulting in excessive stress on a local portion of the seat frame
Solution Approach 1:
The mounting bracket transitions from a traditional point-contact stud/nut connection to a surface-area contact system by engaging both the outside surface and inside surface of the seat frame. This dimensional expansion from linear studs to areal engagement distributes the clamping load across multiple surfaces, reducing stress concentration while maintaining or enhancing overall load capacity.
Solution Approach 2:
The mounting bracket is divided into multiple engagement points including outside surface engagement features and inside surface engagement features. This segmentation allows the total clamping load to be distributed across multiple separate contact areas rather than concentrated at single stud locations, reducing peak stress on the seat frame.
2Stress or pressure
If the bracket engagement area with the seat frame is increased to distribute load, then stress distribution improves, but the size of the bracket is limited by the size and configuration of the seat frame as increasing the area may interfere with other functionalities of the seat
Solution Approach 1:
The mounting bracket utilizes both the outside surface and inside surface of the seat frame for engagement, effectively doubling the available engagement area without increasing the bracket's projection into the seat's functional space. This three-dimensional engagement approach distributes load across greater area while maintaining compact overall dimensions.
Solution Approach 2:
Instead of expanding the bracket outward from the outside surface only, the design inverts part of the engagement to the inside surface of the seat frame. This reverse-direction engagement provides additional load distribution area without interfering with external seat functionalities, as the inside surface engagement occurs within the existing seat structure.
3Ease of manufacture
If modern vehicle seat frames are designed to minimize weight and cost by decreasing material thickness and removing welds, then manufacturing cost and weight are reduced, but the structural integrity of the vehicle seat is weakened
Solution Approach 1:
The mounting bracket engages both the outside surface and inside surface of the seat frame, creating a distributed load path that reduces peak stresses on the thin-walled frame members. This areal engagement approach compensates for the reduced material thickness by spreading forces across larger areas, maintaining structural integrity without requiring thicker materials or additional welds.
Solution Approach 2:
The mounting bracket provides localized reinforcement at the airbag mounting locations through its rigid structure and distributed engagement features. This local quality enhancement strengthens the specific areas subject to airbag deployment forces without requiring overall strengthening of the entire seat frame, thus maintaining weight and cost benefits while improving local structural integrity.
Data Source
AI summary
An airbag assembly including an airbag module mounted to a mounting bracket. The mounting bracket is mounted to an outside surface of a side member of a back frame of a vehicle seat frame and partially covers the outside surface of the side member and extending along a length of the side member. The assembly includes a load transfer device mounted to an inside surface of the side member. The load transfer device distributing a load originating at the airbag module from the mounting bracket to the vehicle seat frame.