GFCI Contact Separation via Torsion Spring Cam Mechanism

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Solution Overview

Problem

Conventional ground fault circuit interrupter (GFCI) devices face challenges in compact design and cost reduction while maintaining reliable electrical isolation and switching functionality.

Innovation Solution

The design incorporates a torsion spring and cam mechanism to achieve independent separation of movable and stationary contacts, reducing the required force for actuation and allowing for a more compact arrangement, with a cost-effective switch design using a spring-biased LED for visual indication.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional GFCI device designs are used, then reliable electrical isolation and switching functionality are maintained, but device size and manufacturing cost increase

Engineering Contradiction:

Improveelectrical isolation and switching functionalityVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent combines the movable contact and stationary contact into a single integrated switch assembly where the movable contact is directly coupled to the actuator through a common structural element. This merging eliminates the need for separate mounting brackets and alignment features, reducing overall device volume while maintaining reliable electrical isolation between hot and neutral lines.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The actuator serves multiple functions: it directly actuates the movable contact for switching, provides the mounting structure for the entire switch assembly, and incorporates the LED indicator mechanism. This multi-functionality reduces the number of separate components needed, thereby reducing device size while maintaining reliable switching functionality.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If conventional GFCI device designs are used, then reliable electrical isolation and switching functionality are maintained, but manufacturing cost increases

Engineering Contradiction:

Improveelectrical isolation and switching functionalityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The switch assembly is designed as an integrated unit where the actuator, movable contact, and LED mounting structure are combined into a single component or pre-assembled module. This reduces the number of separate parts that need to be manufactured, stored, and assembled, thereby reducing manufacturing cost while maintaining reliable electrical isolation through the integrated design.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The actuator is designed to self-mount the entire switch assembly onto the PC board without requiring separate mounting brackets or fasteners. The actuator itself provides the mounting structure, eliminating the need for additional mounting components and simplifying the manufacturing process, which reduces cost while maintaining reliable switching functionality.

Inventive Principle:

Principle #25Self-service

3Reliability

If high actuation force is used, then reliable contact separation is achieved, but device complexity and size increase

Engineering Contradiction:

Improvecontact separationVSAvoidswitch mechanism complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs a cam mechanism with a curved profile that converts rotational motion into linear displacement for contact separation. The curved cam surface provides mechanical advantage, enabling reliable contact separation with reduced actuation force compared to straight-line mechanisms, while maintaining a relatively simple overall structure.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The switch mechanism uses a dynamic cam-based actuation system rather than a static spring-loaded or lever-based system. The cam's rotational motion provides continuous variable mechanical advantage throughout the actuation cycle, enabling reliable contact separation with optimized force requirements and reduced structural complexity.

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 solution enables a compact and cost-effective GFCI device with reliable electrical isolation and efficient operation, providing visual confirmation of states through a spring-biased LED, enhancing both size reduction and manufacturing efficiency.

Implementation Method 1

The design incorporates a torsion spring and cam mechanism to achieve independent separation of movable and stationary contacts

Methodology Applied

Scientific EffectTorsion spring: Torsion Spring

Implementation Method 2

The design incorporates a torsion spring and cam mechanism to achieve independent separation of movable and stationary contacts

Methodology Applied

Scientific EffectCam mechanism: Cam

Implementation Method 3

with a cost-effective switch design using a spring-biased LED for visual indication

Methodology Applied

Scientific EffectLight-emitting diode: Light Emitting Diode

Data Source

PatentUS7623330B2Ground fault circuit interrupter device

Publication Date: 2009.11.24 EATON INTELLIGENT POWER LTD

AI summary

A ground fault circuit interrupter device is described.