Screwless Wire Terminal Clamp for Stable Low-Resistance Connections

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Solution Overview

Problem

Existing electrical wire terminations in screw and clamp type connections are prone to strand relaxation, leading to increased resistance and overheating due to copper wire heating and cooling, necessitating re-torqueing, which is costly and inefficient.

Innovation Solution

A screwless connection terminal system using a clamp spring mechanism with a plunger that moves between open and closed positions to securely clamp wires, ensuring a constant and continuous electrical connection without the need for screws.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If screw and clamp type terminations are used, then electrical connection can be established, but strand relaxation occurs leading to increased resistance and overheating

Engineering Contradiction:

Improveelectrical connection stabilityVSAvoidstrand relaxation

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent removes the screw component entirely from the termination system, extracting the problematic element that causes strand relaxation. The screwless design eliminates the mechanical stress and repeated tightening/loosening cycles that lead to strand relaxation, while maintaining reliable electrical connection through alternative clamping mechanisms.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs a dynamic spring-loaded clamp mechanism that automatically adjusts to maintain optimal contact pressure on the wire. This dynamic system compensates for thermal expansion and contraction of the wire without requiring manual intervention, preventing strand relaxation while ensuring consistent electrical connection.

Inventive Principle:

Principle #15Dynamics

2Ease of operation

If direct pressure type terminations are used, then installation is simplified, but wires can be cut or nicked resulting in poor electrical connections

Engineering Contradiction:

Improveinstallation simplicityVSAvoidelectrical connection quality

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent introduces a controlled clamping mechanism with a movable plate and spring system that acts as an intermediary between the terminal and the wire. This intermediary system provides progressive, controlled pressure that secures the wire without the risk of cutting or nicking, while still achieving reliable electrical connection.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If screw and clamp type terminations are used, then wire clamping can be achieved, but re-torqueing is required increasing installation costs

Engineering Contradiction:

Improvewire clamping stabilityVSAvoidre-torqueing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent implements a self-adjusting spring-loaded mechanism that automatically maintains proper clamping force on the wire throughout operation. The spring continuously compensates for any loosening or thermal effects, making the termination self-servicing and eliminating the need for periodic re-torqueing by installers.

Inventive Principle:

Principle #25Self-service

4Reliability

If screw and clamp type terminations are used, then electrical connection can be established, but copper wire heating and cooling causes strand relaxation

Engineering Contradiction:

Improveelectrical connectionVSAvoidwire thermal cycling

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent employs a dynamic spring-loaded clamp that moves with thermal expansion and contraction of the wire. The spring mechanism absorbs thermal cycling stresses, maintaining constant contact pressure without transmitting harmful mechanical stress to the wire strands, thereby preventing strand relaxation during temperature variations.

Inventive Principle:

Principle #15Dynamics

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 system provides a stable and reliable electrical connection that reduces strand relaxation, maintaining low resistance and preventing overheating, eliminating the need for re-torqueing and reducing installation costs.

Implementation Method 1

The clamp spring is movable relative to the clamp brace between a closed position where a wire can be clamped between the clamp spring and the clamp brace

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

The plunger is interactive with the clamp spring such that movement of the plunger in a first direction relative to the clamp brace causes the plunger to apply a mechanical load to the clamp spring to cause the clamp spring to move from the closed position to the open position

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Data Source

PatentUS20250329947A1Electrical wiring devices with screwless connection terminals

Publication Date: 2025.10.23 HUBBELL INC

AI summary

Electrical wiring devices that incorporate clamp-type 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 and blade-type connectors for electrical cords. The electrical wiring devices include a plurality of contact assemblies. Each contact assembly includes a wire terminal and a plunger.