Fuse Inner Chamber Geometry for Blast Path and Debris Control

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Solution Overview

Problem

Melamine fuses lack a mechanism to effectively control the blast path during an overcurrent event, potentially leading to uncontrolled debris movement and electrical conductivity, which can cause further damage despite the fusible element breaking.

Innovation Solution

Incorporating special layers with geometric elements into the fuse design, which divide the chamber holding the fusible element into sub-chambers, providing pathways for debris movement and attenuating shock waves, thereby reducing the likelihood of electrical conductivity between terminals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If melamine layers are stacked without filler material, then the fuse acts very fast, but the blast path is uncontrolled and fire/sparks may escape

Engineering Contradiction:
Improvefuse acting speedVSAvoiduncontrolled blast path
Core Design Contradiction:
SpeedVSObject-affected harmful factors

Solution Approach 1:

The chamber is divided into multiple sub-chambers by inserting special layers with geometric elements between the melamine layers. This segmentation controls the blast path by creating defined sub-regions that guide debris movement while maintaining the fast-acting characteristic of the original melamine fuse design.

Inventive Principle:
Principle #1Segmentation

2Object-affected harmful factors

If filler material such as sand is added to prevent fire and sparks, then fire/sparks are controlled, but the fuse structure becomes more complex and filling is required

Engineering Contradiction:
Improvefire and sparks controlVSAvoidfuse structure complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The invention removes the filler material (sand) from the fuse structure and replaces it with geometric elements formed directly in the special layers. This extraction eliminates the need for separate filling operations while maintaining blast control functionality, thereby reducing structural complexity.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of filling the entire chamber with sand, geometric elements are strategically positioned at specific locations within the chamber to control blast paths. This localized approach provides fire and sparks control only where needed, reducing overall structural complexity compared to complete filler material implementation.

Inventive Principle:
Principle #3Local quality

3Object-affected harmful factors

If geometric elements are added to divide the chamber, then blast path is controlled, but the device complexity increases

Engineering Contradiction:
Improveblast path controlVSAvoidlayer structure complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The geometric elements are integrated directly into the special layers, combining the functions of structural support and blast control into a single component. This merging eliminates the need for separate filler materials or additional control mechanisms, thereby reducing overall device complexity while maintaining effective blast path control.

Inventive Principle:
Principle #5Merging (Combining)

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 special layers effectively manage the explosive debris, reducing shock wave strength and preventing electrical conductivity, ensuring the fuse's end-of-life event does not cause additional circuit damage.

Implementation Method 1

The geometric elements provide a pathway between the first sub-chamber and the second sub-chamber... attenuating shock waves

Methodology Applied
Scientific EffectShock wave attenuation: Shock Wave

Data Source

PatentEP4318541A1Inner chambers with blast attenuation geometry on fuses
Publication Date: 2024.02.07 LITTELFUSE INC
  • EP4318541A1 patent drawingFigure 1A~1B
  • EP4318541A1 patent drawingFigure 1C~1D
  • EP4318541A1 patent drawingFigure 2A~2B

AI summary

A fuse includes multiple stacked layers, a first terminal, and a second terminal. The first terminal is connected to one end of a fusible element and the second terminal is connected to the other end. The stacked layers include first and second intermediate layers and a special layer. The first intermediate layer, which has a centrally disposed opening, is stacked on the first terminal and the second terminal. The second intermediate layer, also having a centrally disposed opening is stacked above the first intermediate layer, and the centrally disposed openings define a chamber above the fusible element. The special layer is located between the first intermediate layer and the second intermediate layer and includes one or more geometric elements. The geometric elements divide the chamber into two sub-chambers, the first sub-chamber being above the second sub-chamber.