Overcurrent Protection Device Using Thermo Magnetically-Shiftable Material

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Conventional overcurrent protection devices are bulky, require multiple parts, and have different mechanisms for thermal and magnetic protection, leading to inefficiencies in compactness and reliability.

Innovation Solution

A compact overcurrent protection device using a thermo magnetically-shiftable material, such as ferromagnetic shape-memory alloys, which integrates thermal and magnetic protection mechanisms, utilizing a single conductive trigger element that changes magnetically with temperature to open and close the circuit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional bimetallic strips are used for thermal protection, then the device can protect against moderate overcurrent, but the device becomes bulky and requires significant space

Engineering Contradiction:
Improveprotection against moderate overcurrentVSAvoiddevice size
Core Design Contradiction:
ReliabilityVSVolume of stationary object

Solution Approach 1:

The patent changes the physical parameter of the trigger element by using a thermo magnetically-shiftable material that undergoes a magnetic phase transition at a specific Curie temperature. This allows the material to change its magnetic properties (from ferromagnetic to paramagnetic) in response to temperature changes caused by overcurrent, replacing the need for bulky bimetallic strips with a compact material-based solution.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite approach by using a thermo magnetically-shiftable material that combines both thermal response and magnetic actuation properties in a single element. This composite material integrates the functions of thermal sensing and magnetic actuation, eliminating the need for separate bimetallic strip mechanisms and reducing overall device volume.

Inventive Principle:
Principle #40Composite materials

2Measurement precision

If conventional bimetallic strips with mechanical amplification are used, then the device can detect small deflections, but the device requires bulky springs and pinion mechanisms

Engineering Contradiction:
Improvedetection of small deflectionVSAvoidmechanical parts
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical amplification system (springs and pinion mechanisms) with a magnetic field-based actuation system. The thermo magnetically-shiftable material, when heated by overcurrent, loses its ferromagnetic properties and is repelled by a permanent magnet, directly triggering the trip mechanism without requiring mechanical amplification components.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent utilizes the phase transition parameter change of the thermo magnetically-shiftable material at its Curie temperature. This abrupt change in magnetic properties provides a clear, detectable signal for overcurrent conditions, eliminating the need for complex mechanical amplification to detect small deflections.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If thermal and magnetic protection use different physical effects, then the device can provide comprehensive protection, but the device requires more space for implementation

Engineering Contradiction:
Improvecomprehensive protectionVSAvoidspace for mechanisms
Core Design Contradiction:
ReliabilityVSVolume of stationary object

Solution Approach 1:

The patent merges thermal and magnetic protection mechanisms into a single integrated system. The thermo magnetically-shiftable material serves dual purposes: it senses thermal conditions through its temperature-dependent magnetic phase transition and simultaneously acts as the magnetic actuator that triggers the trip mechanism. This consolidation eliminates the need for separate thermal and magnetic protection mechanisms, reducing device volume.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The thermo magnetically-shiftable material performs multiple functions: thermal sensing, magnetic actuation, and trip triggering. This multi-functional element replaces what would traditionally require separate components for thermal protection and magnetic protection, achieving comprehensive protection with reduced space requirements.

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 device achieves a compact design with high reliability, integrating thermal and magnetic protection without bulky mechanical parts, maintaining the open circuit through magnetic interaction, and offering fast response times for both moderate and severe overcurrents.

Implementation Method 1

at least one conductive trigger element, which comprises at least one thermo magnetically-shiftable material configured for a magnetically change in dependence on the temperature induced by a current that flows through the conductor section

Methodology Applied
Scientific EffectThermo magnetic shift: Curie Point (ferromagnetic)

Implementation Method 2

temperature induced by a current that flows through the conductor section

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 3

a conductive magnetic module, a conductive magnetic core, said conductive magnetic module being movable between a first position faced against said conductive trigger element permitting the conduction of the current through the conductor section and a second position faced against said conductive magnetic core breaking the conduction of the current

Methodology Applied
Scientific EffectMagnetic force: Magnetism

Data Source

PatentEP4125109B1Overcurrent protection device based on thermo magnetically-shiftable material
Publication Date: 2025.06.25 CENT NAT DE LA RECH SCI (C N R S)
  • EP4125109B1 patent drawingFigure 1~2
  • EP4125109B1 patent drawingFigure 3~4
  • EP4125109B1 patent drawingFigure 5~6

AI summary

The present invention concerns an overcurrent protection device for a circuit to be monitored, having at least one trigger unit, which is configured for an interruption of the circuit in at least one trigger situation and which comprises at least one conductor section (40) which is configured for a conduction of a current to be monitored, at least one conductive trigger element (30, 31, 32), which comprises at least one thermo magnetically-shiftable material configured for a magnetic property change in dependence on the temperature induced by a current that flows through the conductor section, a conductive magnetic module (20, 21), a conductive magnetic core (10), said conductive magnetic module being movable between a first position faced against said conductive trigger element permitting the conduction of the current through the conductor section and a second position faced against said conductive magnetic core breaking the conduction of the current through the conductor section.