Spring Guide Alignment for Circuit Breaker Carrier Assembly

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Solution Overview

Problem

Existing circuit breaker carrier assembly designs are complex, difficult to assemble, and sensitive to dimensional variations, leading to inconsistent spring force and reduced withstand ratings, with potential for nuisance blow or excessive current leakage.

Innovation Solution

A spring guide system that maintains alignment between contact springs and movable contact arms, reducing the number of springs needed and allowing for larger, more robust springs, facilitating easier assembly and adjustment to achieve higher withstand ratings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional carrier assembly designs with multiple contact springs are used, then the circuit breaker can provide contact pressure and accommodate wear, but the assembly becomes complex and difficult to assemble with numerous parts

Engineering Contradiction:
Improvecontact pressure and wear accommodationVSAvoidnumber of parts and assembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple contact springs into a single integrated spring assembly that provides the necessary contact pressure for multiple contact arms. This merging of multiple separate spring components into one unified structure reduces the total number of parts while maintaining the required mechanical function of providing and maintaining contact pressure across all contacts.

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If traditional carrier assembly designs are used, then the structure can provide blow off functionality, but the assembly is sensitive to dimensional variations resulting in inconsistent spring force

Engineering Contradiction:
Improveblow off functionalityVSAvoiddimensional variation sensitivity
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent introduces a carrier assembly that acts as an intermediary structure between the contact springs and the contact arms. This carrier assembly provides a standardized interface and mounting structure that isolates the spring force application from dimensional variations in the contact arms, ensuring consistent spring force delivery regardless of variations in the contact arm dimensions.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If traditional carrier assembly designs with many contact springs are used, then the assembly can maintain contact pressure, but the alignment of springs with contact arms becomes difficult and time-consuming

Engineering Contradiction:
Improvecontact pressure maintenanceVSAvoidassembly time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent incorporates preliminary alignment features directly into the carrier assembly structure, such as pre-positioned spring mounts and guide features that automatically align the contact springs with the corresponding contact arms during assembly. This preliminary preparation of alignment features eliminates the need for time-consuming manual alignment procedures while ensuring consistent contact pressure maintenance.

Inventive Principle:
Principle #10Preliminary action

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 spring guide system simplifies assembly, ensures consistent spring force, and enhances the circuit breaker's withstand rating, increasing production yield and reducing rejections by allowing for precise adjustment within engineering specifications.

Implementation Method 1

The carrier assembly includes a plurality of contact springs which are structured to bias the fingers and corresponding movable contacts disposed thereon against the stationary contacts in order to provide and maintain contact pressure

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2239749B1Electrical switching apparatus, and carrier assembly and spring guide therefor
Publication Date: 2012.07.25 EATON CORP
  • EP2239749B1 patent drawingFigure 1
  • EP2239749B1 patent drawingFigure 2A~2B
  • EP2239749B1 patent drawingFigure 3

AI summary

A spring guide is provided for a carrier assembly of an electrical switching apparatus such as, for example, a circuit breaker. The carrier assembly includes a carrier body, a plurality of movable contact arms (104) pivotably coupled to the carrier body, and a plurality of contact springs (108). Each of the contact springs is disposed between a portion of the carrier body and a corresponding number of the movable contact arms. Each spring guide includes a guide member (112) disposed between a corresponding one of the contact springs and the corresponding number of movable contact arms to maintains alignment therebetween. The guide member preferably includes a planar portion (116) including a first side, which spans a pair of adjacent movable contact arms, and a second side, which includes a projection (124). The projection is disposed within the coils of the corresponding one of the contact springs.