Lubricant-Coated Fuse Filler for Void-Free High-Power Packing

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Solution Overview

Problem

Large bore high power fuses are sensitive to filler voids created during manufacturing, leading to increased failure rates due to a less than 2% increase in void fraction, which can result in a 50% failure rate.

Innovation Solution

A filling mixture for fuses comprising a filler coated with a thermally stable and electrically insulating lubricant that reduces the coefficient of friction, applied as a solid, liquid, solid powder, or aerosol, increasing packing density and reducing manufacturing issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If filler is packed into large bore fuses during manufacturing, then the fuse can handle high power, but filler voids are created leading to increased failure rates

Engineering Contradiction:
Improvehigh power handling capabilityVSAvoidfailure rate
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The patent changes the physical-chemical parameters of the filler particles by coating them with lubricant, which modifies surface properties (coefficient of friction) and enables better packing density, thereby reducing voids while maintaining high power capability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite structure by coating filler particles with lubricant material, combining the electrical arc-quenching properties of the filler with the low-friction properties of the lubricant to achieve both high power handling and high reliability

Inventive Principle:
Principle #40Composite materials

2Reliability

If filler particles are packed densely to reduce voids, then reliability improves, but manufacturing precision becomes more difficult to achieve

Engineering Contradiction:
Improvefailure rateVSAvoidpacking density control
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent changes the surface friction parameter of filler particles through lubricant coating, which fundamentally alters the packing behavior during manufacturing, enabling high density to be achieved through the material's inherent properties rather than precise process control

Inventive Principle:
Principle #35Parameter changes

3Reliability

If more filler is used to reduce void fraction, then reliability improves, but the coefficient of friction increases making packing difficult

Engineering Contradiction:
Improvevoid fractionVSAvoidpacking process
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent introduces lubricant as an intermediary substance that coats the filler particles, mediating between the filler particles themselves to reduce friction and enable easier, more reliable packing while achieving the desired void fraction reduction

Inventive Principle:
Principle #24Intermediary (Mediator)

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 lubricant-coated filler improves fuse performance, reliability, and manufacturability by lowering friction, maintaining electrical properties, and reducing arc time by up to 45%, while increasing packing density by up to 5%.

Implementation Method 1

a lubricant coating the filler to reduce a coefficient of friction of particles of the filler

Methodology Applied
Scientific EffectLubrication: Lubrication

Implementation Method 2

The liquid or a gas in the aerosol can evaporate after application to leave a dry film that can cover at least some of the particles of the filler

Methodology Applied
Scientific EffectEvaporation: Evaporation

Data Source

PatentEP4641611A1Filling mixture for fuse device
Publication Date: 2025.10.29 LITTELFUSE INC
  • EP4641611A1 patent drawingFigure 1
  • EP4641611A1 patent drawingFigure 2
  • EP4641611A1 patent drawingFigure 3

AI summary

A filling mixture for a fuse device is provided. The fuse device can include a pair of electrical terminals, a metal strip or wire element mounted between the pair of electrical terminals, a housing enclosing the metal strip or wire element, and the filling mixture inside of the housing. The filling mixture can include a filler and a lubricant coating the filler to reduce a coefficient of friction of particles of the filler.