Arc Extinguishing Chamber Assembly for Heat-Resistant Grid Holding

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Solution Overview

Problem

Conventional arc extinguishing chamber units in circuit breakers face thermal damage from arc gas, leading to degradation of grid holding function and difficulty in automated assembly.

Innovation Solution

A circuit breaker design with a synthetic resin unit case comprising a first case holding grids and a second case with clamping ribs, allowing for automated assembly by clamping the rear sides of the grids, and an exhaust hole to vent arc gas externally.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the pair of side walls near the exhaust hole apply force to sandwich and hold the grids, then the grids are held to be arranged in layers, but the side walls are thermally damaged by arc gas, causing the holding function to be lost

Engineering Contradiction:

Improvegrid holding functionVSAvoidthermal damage from arc gas

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The unit case is divided into a first case and a second case. The first case holds the grids, while the second case is positioned near the exhaust hole and forms a protective barrier against arc gas. This segmentation allows the grids to be held securely without exposing the holding structure directly to thermal damage from arc gas.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second case acts as an intermediary between the exhaust hole and the first case holding the grids. It shields the first case and grids from direct exposure to arc gas, preventing thermal damage while maintaining the grid holding function.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If other components are incorporated in the unit case to protect against thermal damage, then the grid holding function is preserved, but the unit case becomes difficult to assemble by automation

Engineering Contradiction:

Improvegrid holding functionVSAvoidautomated assembly

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The unit case is segmented into a first case and a second case that can be assembled separately. The first case is prepared with grids, and the second case is then coupled to it, enabling automated assembly processes while maintaining protective functions against thermal damage.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The grids are pre-positioned in the first case before the second case is coupled to it. This preliminary arrangement allows automated assembly systems to efficiently place and secure the grids without requiring complex in-situ adjustments during final assembly.

Inventive Principle:

Principle #10Preliminary action

3Object-affected harmful factors

If the second case is coupled to the first case to form a complete unit case, then the grids are protected from arc gas, but the assembly process becomes complex

Engineering Contradiction:

Improveprotection from arc gasVSAvoidassembly process

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The unit case is divided into two separable cases that can be manufactured and prepared independently, then coupled together. This segmentation simplifies the overall assembly process by allowing modular preparation and reducing the complexity of handling the complete unit case as a single complex component.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first case is designed to hold the grids in a self-supporting manner before the second case is attached. This self-service capability allows the grids to be positioned and secured without requiring complex fixtures or support structures during the assembly process.

Inventive Principle:

Principle #25Self-service

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

Maintains the grid holding function over a long period and enables automated assembly of the arc extinguishing chamber unit.

Implementation Method 1

the exhaust hole in the rear wall receives the flow of hot arc gas from an arc generated in the switching contact point

Methodology Applied

Scientific EffectGas flow:

Implementation Method 2

the second case being formed with clamping ribs capable of clamping the rear sides of the grids

Methodology Applied

Scientific EffectMechanical clamping: Mechanical Force

Data Source

PatentUS20260004985A1Circuit breaker and method for assembling arc extinguishing chamber unit in circuit breaker

Publication Date: 2026.01.01 FUJI ELECTRIC FA COMPONENTS & SYST CO LTD

AI summary

A circuit breaker comprises a switching contact point configured by a fixed contact having a fixed contact point and a moving contact having a moving contact point, and an arc extinguishing chamber unit configured to extinguish an arc generated between the fixed contact point and the moving contact point. The switching contact point and the arc extinguishing chamber unit being arranged in a case. The arc extinguishing chamber unit includes a unit case and a plurality of grids arranged in layers in the unit case. The unit case includes a first case arranged near the switching contact point and configured to hold the plurality of grids and a second case configured to close an opening part of the first case and detachably coupled to the first case, and formed with an exhaust hole configured to exhaust arc gas to an outside.