Reinforced Circuit Breaker Housing for Arc Extinction

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Solution Overview

Problem

Existing electric circuit breaker devices are bulky due to the need for thick polymer housings or heavy stainless steel casings to provide strength, and they face challenges in extinguishing arcs that occur during conductor cutting, complicating their structure and assembly.

Innovation Solution

The device features a synthetic resin housing with a bar-shaped projectile and a conductor piece, reinforced by a metal cylinder and a U-shaped reinforcing frame, which allows for a downsized design while maintaining necessary strength and effectively extinguishing arcs through a discharge path for combustion products.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a polymer material housing is used, then the housing provides electrical insulation, but the housing must be formed thick to give necessary strength, increasing the device size

Engineering Contradiction:
Improveelectrical insulationVSAvoidhousing thickness
Core Design Contradiction:
ReliabilityVSVolume of stationary object

Solution Approach 1:

The housing is made of a composite material comprising a base material layer and a reinforcement layer. The base material layer provides electrical insulation, while the reinforcement layer (made of fiber-reinforced material or metal) provides mechanical strength. This composite structure allows the housing to be thinner while maintaining both insulation and strength properties.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The reinforcement layer is strategically positioned in specific areas of the housing where mechanical strength is most needed, such as around the arc extinguishing chamber and conductor piece mounting areas. This localized reinforcement allows other areas to be thinner, reducing overall device size while maintaining necessary strength.

Inventive Principle:
Principle #3Local quality

2Strength

If a stainless steel casing is used, then the housing provides necessary strength, but the mass increases and additional insulating case is needed, complicating structure and assembly

Engineering Contradiction:
Improvehousing strengthVSAvoidstructure and assembly
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The housing is designed to simultaneously provide both structural strength and electrical insulation functions through its composite structure. The base material layer provides insulation while the reinforcement layer provides strength, eliminating the need for separate insulating and structural components that would be required if using stainless steel alone.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The housing combines the previously separate functions of the insulating case and the reinforcing structure into a single integrated component. The composite housing structure merges the insulation function and strength function into one element, simplifying both the device structure and assembly process.

Inventive Principle:
Principle #5Merging (Combining)

3Volume of stationary object

If the housing is downsized, then the device becomes more compact, but the strength of the housing may be compromised

Engineering Contradiction:
Improvedevice sizeVSAvoidhousing strength
Core Design Contradiction:
Volume of stationary objectVSStrength

Solution Approach 1:

The composite housing structure provides high strength-to-weight ratio and high strength-to-volume ratio. The reinforcement layer with fibers or metal mesh provides exceptional mechanical strength in a thin profile, allowing the housing to be compact while maintaining necessary strength to contain the arc and protect internal components.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The reinforcement layer can be designed with a porous or mesh structure that provides high strength while maintaining flexibility and allowing for compact device design. The porous structure allows the housing to be thinner while the strategic placement of reinforcement material provides necessary structural integrity.

Inventive Principle:
Principle #31Porous materials

4Reliability

If an arc extinguishing chamber is added, then arcs can be extinguished when conductor is cut, but the device structure becomes more complex

Engineering Contradiction:
Improvearc extinguishing capabilityVSAvoidstructure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The arc extinguishing chamber is merged with the housing structure rather than being a separate component. The housing itself forms the arc extinguishing chamber through its internal geometry and the placement of the conductor piece, eliminating the need for additional separate arc extinguishing components and simplifying the overall device structure.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The housing serves multiple functions simultaneously: it provides electrical insulation, mechanical strength, structural support, and arc extinguishing capability. The multi-functional design integrates the arc extinguishing chamber into the housing structure, avoiding additional components and reducing device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 electric circuit breaker device that can handle high currents and extinguish arcs, improving durability and reducing the overall size by utilizing a synthetic resin housing reinforced with a metal cylinder and frame, ensuring effective arc extinction and enhanced structural integrity.

Implementation Method 1

an igniter, a bar-shaped projectile made of a synthetic resin, and a conductor piece to form a part of an electric circuit are disposed in this order from a first end side of the housing to an axially opposite second end side of the housing

Methodology Applied
Scientific EffectCombustion: Combustion

Implementation Method 2

a discharge path for combustion products generated by actuation of the igniter is provided between the insulating space and the second end of the housing

Methodology Applied
Scientific EffectCombustion products discharge: Combustion

Data Source

PatentEP3480838B1Electric circuit breaker
Publication Date: 2024.02.14 DAICEL CORP
  • EP3480838B1 patent drawingFigure 1
  • EP3480838B1 patent drawingFigure 2(a)~2(b)
  • EP3480838B1 patent drawingFigure 3~4

AI summary

To provide an electric circuit breaker device that can be downsized while maintaining strength. An igniter 20, a bar-shaped projectile 40, a conductor piece 50, and an insulating space 61 are provided inside a resin housing 10. A cylinder 30 is disposed between the bar-shaped projectile 40 and an inner wall surface of the housing 10, and further, a reinforcing frame 70 is disposed in the housing 10 on the outer side. A discharge path for combustion products generated by actuation of the igniter 20 is provided between the insulating space 61 and a second end 12 of the housing.