Self-Locking Fastener for Large-Tolerance Panel Openings
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Solution Overview
Problem
Existing fasteners require multiple steps for installation and struggle to reliably fit holes with large manufacturing tolerances, leading to issues like buzz, squeak, and rattle (BSR) due to inconsistent connections.
Innovation Solution
A fastener design that allows single-step installation by compressing resilient legs into a deflected state, using a push bar and lock tabs to secure the fastener within openings with large tolerances, ensuring a stable connection through a pair of locking features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fasteners are used to secure panels, then the connection can be established, but multiple installation steps are required and holes with large manufacturing tolerances cannot be reliably fitted
Solution Approach 1:
The fastener is divided into distinct functional segments: a head portion with lock tabs, a lead-in portion for insertion, a shank, a push bar with chamfered edges, and resilient legs. This segmentation allows each component to perform its specific function during single-step installation, resolving the contradiction between reliability and installation complexity.
Solution Approach 2:
The resilient legs are pre-configured in a deflected state that allows them to compress during insertion. The lock tabs are positioned to engage with the push bar before final insertion. This preliminary configuration enables the fastener to automatically accommodate tolerance variations and lock into place during a single installation motion, eliminating multiple steps while ensuring reliable connection.
2Ease of operation
If fasteners are designed to fit holes with large tolerances, then single-step installation is enabled, but connection stability may be compromised
Solution Approach 1:
The fastener utilizes elastic deformation of the resilient legs as a key parameter change mechanism. During insertion, the legs compress from their deflected state, generating clamping force that adapts to holes with large tolerances. The lock tabs and push bar engage to maintain the legs in this compressed state, providing both ease of single-step installation and stable connection through the sustained clamping force.
Solution Approach 2:
The resilient legs provide dynamic adaptation during installation, allowing the fastener to adjust to varying hole dimensions within tolerance ranges. The legs compress and lock into position, creating a stable connection that accommodates manufacturing variations while maintaining connection stability through the locked, compressed state.
3Productivity
If resilient legs are compressed to accommodate tolerance variations, then single-step installation is achieved, but the fastener may withdraw without locking features
Solution Approach 1:
The fastener is designed as a self-locking mechanism where the push bar automatically engages with the lock tabs during insertion. The chamfered edges of the push bar guide the lock tabs into engagement, and the resilient legs maintain compression force to prevent withdrawal. This self-service locking mechanism achieves both high installation speed and reliable retention without requiring additional locking steps.
4Reliability
If lock tabs and push bar are used to secure the fastener, then withdrawal is prevented, but manufacturing complexity increases
Solution Approach 1:
The lock tabs, push bar, and resilient legs are integrated into a single molded fastener body. The lead-in portion connects these components in a unified structure that can be manufactured in one process. This merging of components achieves reliable fastening security through the interlocking lock tabs and push bar while maintaining manufacturing simplicity through integral construction.
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 provides secure, single-step installation and reduces BSR issues by accommodating large manufacturing tolerances, maintaining a consistent clamping force and preventing withdrawal, thus enhancing reliability and efficiency.
Implementation Method 1
a pair of resilient legs extending between the head portion and the lead-in portion, the resilient legs being configured to compress into a deflected state as the lead-in portion passes through the opening
Data Source
AI summary
A fastener to connect a first component to a second component with an opening. The fastener includes a head with two lock tabs, each shaped with a sloped sidewall, and a lead-in portion that fits into the opening. A shank connects the lead-in portion to a push bar, which has at least one angled (chamfered) edge. Flexible legs extend between the head and the lead-in portion and compress as the lead-in portion is inserted. During installation, the chamfered edge of the push bar slides against the sloped sidewall of the lock tabs, allowing the push bar to move past them. Once in place, the lock tabs hold the push bar, keeping the flexible legs compressed and locking the fastener securely.