Tool-Free Threadless Connector for EMT Conduit
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Solution Overview
Problem
Existing connectors for electrical metallic tubing (EMT) require tools to assemble and disassemble, making it difficult for users to achieve the necessary axial pull-out force without assistance, as they are not capable of being threaded.
Innovation Solution
A tool-free threadless connector with an interior retainer ring featuring angled teeth segments that securely engage the conduit, allowing for tool-free installation and removal by rotating the conduit while applying axial force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If compression grip ring or screw type connector is used to secure conduit, then axial pull-out force is maintained, but tool-free installation and removal cannot be achieved
Solution Approach 1:
The retainer ring is segmented into multiple teeth segments rather than being a continuous ring. This segmentation allows the teeth to individually engage with the conduit surface, distributing the gripping force while maintaining overall holding strength. The segmented structure enables tool-free installation as the teeth can flex and conform to the conduit during insertion, yet still provide sufficient axial pull-out resistance when engaged.
Solution Approach 2:
The teeth segments are configured with asymmetric geometry, having different profiles on opposing sides. One side of each tooth segment has a leading edge that facilitates easy insertion and engagement with the conduit, while the opposite side provides the gripping surface that resists pull-out forces. This asymmetry allows the connector to be installed without tools while maintaining the necessary holding force.
2Reliability
If threaded connection is used for EMT conduit, then secure connection is achieved, but EMT conduit cannot be threaded
Solution Approach 1:
The patent replaces the traditional threaded mechanical connection system with a friction-based engagement system. Instead of requiring threads to be cut into the EMT conduit, the retainer ring uses friction between its teeth segments and the conduit outer surface to create a secure connection. This substitution allows the connector to work with EMT conduit's smooth outer surface without requiring threading operations.
Solution Approach 2:
The retainer ring acts as an intermediary between the connector body and the conduit. Rather than directly threading into the conduit, the retainer ring mediates the connection by engaging the conduit's outer surface through friction and normal forces. This intermediary approach enables secure connection without requiring the conduit to be threaded, making it compatible with EMT conduit.
3Ease of operation
If compression connector is used to engage conduit, then connection is secured, but tool-free assembly cannot be achieved
Solution Approach 1:
The patent merges the functions of the compression ring and the engagement mechanism into a single integrated retainer ring structure. The retainer ring simultaneously provides the compression function to secure the conduit and the engagement function through its teeth segments. This merging eliminates the need for separate compression mechanisms and simplifies the overall connector structure, enabling tool-free assembly while maintaining connection security.
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 efficient assembly and disassembly of EMT conduit connections without tools, maintaining sufficient axial pull-out force and electrical conductivity.
Implementation Method 1
engaging an outer surface of the conduit with the plurality of teeth segments of the retainer ring
Implementation Method 2
the plurality of teeth segments are configured to be inwardly angled to contact an end of a conduit inserted into the connector body
Data Source
AI summary
A threadless connector includes a connector body having a central bore therethrough and a retainer ring disposed in an end of the connector body. The retainer ring has a plurality of teeth segments inwardly angled to contact an end of a conduit inserted into the connector body.