Helical Gripping Tabs for EMT Fitting Pullout Resistance
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Solution Overview
Problem
Existing electrical fittings and connectors for metallic tubing are difficult to remove without disassembly or cutting, making modifications time-consuming and challenging in construction settings.
Innovation Solution
A push-fit electrical connector with helically arranged gripping tabs that securely hold metallic tubing for easy assembly and allow easy removal by twisting, featuring a contact rib for improved continuity and rounded corners for secure engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional electrical fittings use tabs or teeth to grip metallic tubing, then the tubing is securely held, but the tubing cannot be removed without cutting or disassembly
Solution Approach 1:
The gripping tabs are designed to be flexible and dynamic rather than rigid. They can deflect inward during installation to allow tubing insertion, then spring outward to grip the tubing securely. For removal, the tabs can be compressed inward again to release the tubing, enabling easy installation and removal while maintaining secure holding during operation
Solution Approach 2:
The gripping force of the tabs is changed from a constant static force to a variable force that can be adjusted. During installation, the tabs are in a relaxed state allowing insertion. During normal operation, they exert outward gripping force to hold the tubing securely. During removal, the tabs are compressed to reduce gripping force, allowing easy removal without cutting
2Strength
If fittings are designed with strong gripping mechanisms, then tubing pullout resistance is improved, but modification and reconfiguration become time-consuming
Solution Approach 1:
The gripping mechanism uses spring-loaded tabs that can dynamically adjust their gripping force. For strong holding during operation, the tabs spring outward to grip the tubing firmly. For modifications, the tabs can be quickly compressed inward to release the tubing, enabling rapid reconfiguration without cutting or time-consuming disassembly procedures
3Reliability
If tabs are positioned at different positions relative to the longitudinal axis, then secure engagement is achieved, but removal becomes difficult
Solution Approach 1:
The gripping tabs are arranged in a helical or spiral pattern around the longitudinal axis rather than in straight radial lines. This curved arrangement allows the tabs to engage the tubing securely at multiple points around the circumference. For removal, a twisting motion engages the helical pattern, allowing the tabs to sequentially release and guide the tubing out, combining secure engagement with easy removal
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
Enables secure holding and easy removal of metallic tubing without disassembly, reducing construction time and costs by allowing quick changes and modifications without cutting the tubing.
Implementation Method 1
The gripping tabs flex away from an opening in the fitting permitting the electrical metallic tubing to be pushed into the fitting through the opening. The angled gripping tabs prevent the electrical metallic tubing from being pulled away from the fitting.
Data Source
AI summary
An electrical fitting having a gripping device with a plurality of gripping tabs forming a helix or spiral. The gripping tabs have a twist creating increased pullout resistance and easier disassembly. The electrical fitting permits electrical metallic tubing or EMT to be quickly attached to and removed from the electrical fitting without disassembling the fitting or cutting the tubing. A body with a locking end having a plurality of griping tabs receives an end of the tubing pushed into the fitting. The gripping tabs securely hold the tubing preventing loosening or removal. The helix or spiral and twist formation of the griping tabs permits easy removal of the tubing by rotating the tubing counter-clockwise.