Magnetic Actuator Circuit Layout Without Spring Preload

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Solution Overview

Problem

Magnetic actuators for low-voltage electric systems have complex structures with many parts, requiring tight mechanical tolerances and are difficult to manufacture at industrial scale, and their performance is sensitive to environmental temperature.

Innovation Solution

A magnetic actuator with a simplified structure featuring a magnetic circuit with three parallel branches, asymmetric airgap regions, and a configuration that varies magnetic reluctances to facilitate movement of the movable armature without additional mechanical means.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional magnetic actuator structure with permanent magnet and pre-loaded spring is used, then the actuator provides reliable mechanical actuation force, but the structure becomes complex with many parts requiring tight mechanical tolerances and high manufacturing cost

Engineering Contradiction:
Improvemechanical actuation forceVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts and removes the pre-loaded spring component from the magnetic actuator structure. The spring mechanism is completely eliminated, leaving only the essential magnetic circuit components (magnetic yoke, magnetic armature, and coil). This extraction simplifies the structure while maintaining the actuation function through magnetic forces alone.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention merges the functions of multiple components into a simplified magnetic circuit. The magnetic yoke, magnetic armature, and coil work together as an integrated system where the coil generates magnetic flux that directly produces the actuation force on the armature, eliminating the need for separate spring mechanisms.

Inventive Principle:
Principle #5Merging (Combining)

2Power

If a traditional magnetic actuator structure with multiple components is used, then the actuator achieves the required actuation performance, but the manufacturing cost increases due to tight mechanical tolerances and assembly complexity

Engineering Contradiction:
Improveactuation performanceVSAvoidmanufacturing cost
Core Design Contradiction:
PowerVSEase of manufacture

Solution Approach 1:

By removing the spring component and associated mechanical tolerance requirements, the invention significantly reduces manufacturing complexity and cost. The simplified structure requires fewer precision-critical parts and less complex assembly procedures while maintaining actuation performance.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If a magnetic actuator with pre-loaded spring and multiple components is used, then the actuator provides stable operation, but the behavior becomes sensitive to environmental temperature variations

Engineering Contradiction:
Improveoperation stabilityVSAvoidtemperature sensitivity
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The invention removes the spring component that is susceptible to temperature-induced dimensional changes and elastic property variations. By eliminating this thermally sensitive mechanical element, the actuator's operation becomes less dependent on environmental temperature conditions.

Inventive Principle:
Principle #2Taking out (Extraction)

4Device complexity

If a simplified magnetic actuator structure is used, then the manufacturing cost and complexity are reduced, but the actuation force mechanism must be redesigned

Engineering Contradiction:
Improvestructure simplicityVSAvoidactuation mechanism design
Core Design Contradiction:
Device complexityVSEase of manufacture

Solution Approach 1:

The invention replaces the mechanical spring-based actuation mechanism with an electromagnetic system. The coil generates magnetic flux that directly acts on the magnetic armature to produce the required actuation force, substituting mechanical elasticity with electromagnetic forces.

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

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 actuator achieves reliable operation with a reduced number of parts, easier manufacturing, and improved resistance to temperature variations, while maintaining efficient mechanical actuation.

Implementation Method 1

a permanent magnet configured to feed said fixed and movable magnetic armatures with a first magnetic flux having a predefined direction

Methodology Applied
Scientific EffectMagnetic flux: Magnetic Field

Implementation Method 2

The magnetic armature is maintained coupled to the yoke plates due to the magnetic force deriving from the magnetic flux generated by the permanent magnet

Methodology Applied
Scientific EffectMagnetic coupling: Magnetism

Implementation Method 3

a current is fed into the actuation coil. The coil current generates a temporary magnetic flux in opposition to the magnetic flux generated by the permanent magnet

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 4

the first and second airgap regions differ one from another... the magnetic circuit is configured so that the first magnetic reluctance of said first branch decreases and the second magnetic reluctance of said second branch increases

Methodology Applied
Scientific EffectMagnetic reluctance: Magnetic Reluctance

Data Source

PatentEP4439617B1A magnetic actuator for low-voltage electric systems
Publication Date: 2026.05.06 ABB (SCHWEIZ) AG
  • EP4439617B1 patent drawingFigure 1
  • EP4439617B1 patent drawingFigure 2
  • EP4439617B1 patent drawingFigure 3

AI summary

A magnetic actuator for low-voltage electric systems, wherein magnetic actuator comprises a magnetic circuit including: - a fixed magnetic armature and a movable magnetic armature, said movable magnetic armature being movable between a first position and a second position relative to said fixed magnetic armature; - a permanent magnet configured to feed said fixed and movable magnetic armatures with a first magnetic flux having a predefined direction, when said permanent magnet is in a magnetized condition; wherein said magnetic actuator further comprises an excitation coil magnetically coupled to said magnetic circuit and configured to be fed with an electric current, when a tripping manoeuvre of said magnetic actuator is required, wherein the magnetic circuit has three branches forming two magnetic loops having a branch in common.