Fastener Clip Assembly with Locking Arms for Chassis Attachment
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Solution Overview
Problem
Conventional fasteners for attaching vehicle body panels to chassis suffer from high insertion force and low extraction force, leading to wing breakage, misalignment issues, and inability to self-align, which results in rattling, corrosion, and inadequate security under varying environmental conditions and production tolerances.
Innovation Solution
A two-piece fastener clip assembly with a tub and blade design, featuring independent wings that bend and spring back for secure engagement, and a 'H' shaped rib for strength, along with spring fingers for enhanced retention and adaptability to misalignment, made from injection moldable plastic or metal for improved durability and reusability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional single-piece fasteners are used, then manufacturing cost is reduced, but the fastener is prone to wing breakage and cannot self-align when misaligned
Solution Approach 1:
The fastener is divided into two separate pieces: a clip portion and a fastener portion. The clip portion includes wings that can independently flex and engage with the frame slot, while the fastener portion includes a blade that attaches to the body panel. This segmentation allows each piece to be optimized for its specific function, with the wings designed to flex and absorb misalignment forces without breaking the entire fastener.
Solution Approach 2:
The wings are designed with specific geometric parameters including a leading edge angle of 10-45 degrees and a width-to-length ratio of 0.2-0.5, which optimize the flexing characteristics and engagement forces. These parameter changes enable the wings to self-align with the frame slot while maintaining sufficient engagement strength to prevent wing breakage.
2Device complexity
If conventional fasteners provide equal insertion and extraction force, then simplicity is maintained, but panel security is inadequate under varying environmental conditions
Solution Approach 1:
The fastener system transitions from a static force profile to a dynamic one where insertion force and extraction force are differentiated. The spring-loaded clip portion provides continuous engagement force that adapts to varying environmental conditions such as vibration, thermal expansion, and panel warping, maintaining secure panel attachment throughout the service life.
Solution Approach 2:
The spring mechanism in the clip portion acts as a feedback system that continuously monitors and adjusts the engagement force. When external forces attempt to disengage the fastener (such as vibration or thermal effects), the spring automatically increases the engagement force to maintain secure attachment, providing active compensation for environmental variations.
3Strength
If sharp grooves are used for slot engagement, then initial engagement is secure, but the grooves are cut by slot edges during removal making reinsertion impossible
Solution Approach 1:
The rounded leading edges of the wings are designed to initially engage the sharp slot edges created by the punching process. Rather than being damaged by these sharp edges, the rounded geometry allows the wings to flex and ride over the sharp edges during insertion, converting the potentially harmful sharp edges into a beneficial self-aligning feature that guides the wings into proper engagement.
Solution Approach 2:
The wings are designed as flexible elastic elements that can deform during insertion and engagement. This flexibility allows the wings to conform to the slot geometry, absorb the impact of sharp slot edges, and maintain engagement through repeated insertions and removals without being cut or damaged by the slot edges.
4Ease of manufacture
If conventional fasteners are used with slot misalignment, then manufacturing tolerances are simplified, but twisting of the body panel occurs due to unequal wing forces
Solution Approach 1:
The wings are designed with asymmetric geometry relative to the slot, with rounded leading edges and specific angle configurations that allow one wing to engage the slot edge first during insertion. This asymmetric engagement sequence allows the fastener to self-align with the slot even when there is misalignment, distributing the engagement forces evenly and preventing body panel twisting.
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 fastener clip assembly maintains a high extraction force to removal force ratio, reduces buzzing and rattling, and accommodates production tolerances, ensuring secure and aesthetically appealing attachment of body panels to the chassis while allowing for easy reinstallation and durability.
Implementation Method 1
spring fingers for enhanced retention and adaptability to misalignment
Implementation Method 2
locking arms that engage the blade to prevent movement of the body panel
Data Source
AI summary
Fastener clip including a tub that may be configured to engage and be secured to a slot in a chassis. The tub comprising at least two wings have a top portion and a bottom portion. The at least two wings are attached to the tub along a top portion of each of the wings on opposite sides of the tub. Bottom portions of the wings engage the chassis, securing the tub to the slot. The tub comprises at least two hooks on opposite sides of the tub and located laterally to the wings. The wings are configured to bend in response to the tub being inserted into a rib. The rib has tabs with outside edges to engage the hooks. Each of the tabs on the rib may be tapered to form tapered tabs. At the end of each tab, a retention notch engages the hook on the tub.