Fixing Clip Load Sharing for Curtain Airbag Endurability

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Solution Overview

Problem

Conventional fixing clips for curtain airbags are prone to failure under excessive drawing-out loads due to the lack of load-sharing capability of the lock pin, leading to leg breakage and disconnection from the body panel, with limited options to increase leg cross-sectional area without compromising installation and removal.

Innovation Solution

A fixing clip design featuring a bushing with paired engagement hooks and a lock pin that includes a load-receiving portion to share the reaction force of the drawing-out load, reducing the load on the leg and incorporating a side hook and pressure receiving surface to distribute the load effectively, enhancing the clip's endurability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the cross-sectional area of the leg is increased to prevent breakage, then the strength and endurability of the fixing clip is improved, but it becomes difficult to pass the leg through the clip fixing aperture, compromising installation and removal ease

Engineering Contradiction:
Improveendurability of the legVSAvoidease of installation and removal
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The lock pin serves as an intermediary load-bearing component that shares the drawing-out load with the bushing. By introducing this intermediate element, the leg does not need to bear the entire load alone, allowing it to maintain a smaller cross-sectional area that can pass through the clip fixing aperture while still achieving sufficient endurability through the combined load-sharing mechanism of the lock pin and bushing.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If the lock pin is designed only to prevent engagement hook deformation, then the structural simplicity is maintained, but the endurability against drawing-out load is insufficient due to inability to share the load

Engineering Contradiction:
Improvestructural simplicityVSAvoidendurability against drawing-out load
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The lock pin is designed with multi-functionality: it not only prevents the engagement hooks from deforming toward the center axis line (original function) but also receives and shares the drawing-out load through its load receiving portion (new function). This universal design allows a single component to perform multiple functions, maintaining structural simplicity while significantly improving endurability against drawing-out loads.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Device complexity

If the engagement hooks bear the entire drawing-out load, then the load transmission path is simple, but the leg will break at the connecting portion to the head when the load exceeds endurability

Engineering Contradiction:
Improvesimplicity of load transmission pathVSAvoidresistance to drawing-out load
Core Design Contradiction:
Device complexityVSStrength

Solution Approach 1:

The load transmission path is segmented into multiple load-bearing components: the lock pin receives a portion of the drawing-out load through its load receiving portion, and the bushing receives the remaining load through its pressure receiving surface. This segmentation distributes the load across multiple components rather than concentrating it entirely on the leg, preventing breakage while maintaining a relatively simple overall structure.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3073129B1Fixing clip and fixing structure for fixing a member to be installed using the fixing clip
Publication Date: 2022.08.24 TOYOTA JIDOSHA KK
  • EP3073129B1 patent drawingFigure 1
  • EP3073129B1 patent drawingFigure 2
  • EP3073129B1 patent drawingFigure 3

AI summary

A fixing clip (10) is used for fixing a member (94) to be installed to a body panel (90) and includes a bushing (20) and a lock pin (50). The bushing (20) includes a head (22) and a leg (30). The lock pin (50) includes a load receiving portion (52) including a load receiving surface (52B, 52C) which receives a part (Fa) of a reaction force (Fr) of a drawing-out load (F) loaded on the fixing clip (10) from the body panel (90), when the drawing-out load (F) acts on the fixing clip (10) from the member (94) to be installed. The bushing (20) includes a pressure receiving surface (26) for receiving the part (Fa) of the reaction force (Fr) of the drawing-out load (F) which the lock pin (50) has received. According to this lock pin (50), the drawing-out load (F) can be received by both of the bushing (20) and the lock pin (50). As a result, an endurability of the fixing clip (10) against the drawing-out load (F) can be improved by an amount of the load (Fa) which the lock pin (50) shares, so that the drawing-out load (F) which the fixing clip (10) receives can be increased.