Screwless Wire Terminals with Spring-Loaded Clamp Arms
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Solution Overview
Problem
Existing electrical wire terminations, particularly direct pressure and screw and clamp types, are prone to issues such as wire damage, poor connections, and strand relaxation, leading to increased resistance and overheating, especially with stranded wires, which necessitate re-torquing of terminal screws over time, increasing installation costs.
Innovation Solution
The development of a twist lock electrical receptacle with screwless wire terminals that incorporate a wire terminal and an activating member, allowing for secure clamping of wires without screws, using a clamp brace and force applying member that can be moved between open and closed positions via an activating member, ensuring constant mechanical energy application for secure wire connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If direct pressure type terminations are used, then the wire terminal structure is simple, but the wire can be cut or nicked resulting in poor electrical connections
Solution Approach 1:
The patent introduces a clamp body as an intermediary component between the wire and the terminal screw. The clamp body includes a clamp jaw that cradles the wire and a clamp arm that applies clamping force, acting as a mediator that protects the wire from direct contact with the terminal screw while ensuring reliable electrical connection. This resolves the contradiction by maintaining structural simplicity while improving connection reliability through the intermediary clamp mechanism.
2Reliability
If screw and clamp type terminations are used, then the wire is clamped between plates, but strand relaxation occurs causing increased resistance and overheating
Solution Approach 1:
The patent employs a spring-loaded clamp arm that automatically maintains constant clamping force on the wire. The spring mechanism provides self-service by continuously applying pressure to compensate for strand relaxation, eliminating the need for manual re-torquing. This resolves the contradiction by ensuring reliable wire clamping while maintaining stability against strand relaxation through the self-adjusting spring mechanism.
Solution Approach 2:
The clamp arm is designed to be movable rather than fixed, allowing it to dynamically adjust to wire position and compensate for strand relaxation. The spring-loaded mechanism enables the clamp to maintain optimal contact pressure over time, resolving the contradiction between initial clamping reliability and long-term stability against strand relaxation.
3Reliability
If terminal screws are re-torqued to alleviate strand relaxation, then connection reliability is maintained, but installation costs increase
Solution Approach 1:
The spring-loaded clamp mechanism is pre-configured during manufacturing to automatically maintain constant clamping force. This preliminary action eliminates the need for subsequent re-torquing operations, as the spring mechanism continuously compensates for strand relaxation without human intervention. This resolves the contradiction by ensuring connection reliability while preventing the loss of time and additional costs associated with re-torquing.
4Device complexity
If direct pressure type terminations are used, then the terminal structure is simple, but the electrical connection resistance increases due to poor connections
Solution Approach 1:
The clamp body with clamp jaw and clamp arm serves as an intermediary that ensures optimal wire contact. The clamp jaw cradles the wire to prevent damage while the clamp arm applies consistent pressure, maintaining low electrical resistance. This resolves the contradiction by keeping the terminal structure relatively simple while significantly improving electrical connection reliability through the intermediary clamp mechanism.
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
This solution provides a reliable and cost-effective electrical connection that minimizes wire damage and strand relaxation, maintaining consistent contact resistance over time without the need for re-torquing, thus reducing installation costs and improving connection reliability.
Implementation Method 1
The wire terminal includes a clamp brace and a force applying member secured to the clamp brace. The force applying member is movable relative to the clamp brace between a closed position where a wire can be clamped between the force applying member or mechanical energy device and the clamp brace
Implementation Method 2
The force applying member is movable relative to the clamp brace between a closed position where a wire can be clamped between the force applying member or mechanical energy device and the clamp brace
Data Source
AI summary
Electrical wiring devices that incorporate screwless wire terminal connections are described. The electrical wiring devices include for example, single and duplex blade-type electrical receptacles, blade-type locking electrical receptacles, single or multi-pole electrical switches, combination switches and blade-type receptacles, blade-type plugs for electrical cords, blade-type connectors for electrical cords, male and female inlet connectors and pin-in-sleeve connectors. The electrical wiring devices include a plurality of contact assemblies having a horizontally moving or rotating activating member that permits wires to be inserted into or removed from the contact assemblies.