Motor Protection Switch Armature Assembly Inversion

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Solution Overview

Problem

Existing motor protection switches with magnetic releases face challenges in simple assembly of the armature with the coil and bobbin, requiring complex threading procedures.

Innovation Solution

The design incorporates a bobbin with radial flanges and stepped armature sections, allowing for easier assembly by plugging the bobbin into the yoke and using a tether spring to secure the armature, with the larger diameter section inside the coil for increased magnetic force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the armature is threaded through a closed opening in the first leg, then the magnetic release structure is secure, but the assembly process becomes complex and time-consuming

Engineering Contradiction:
Improvestructural securityVSAvoidassembly simplicity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

Instead of threading the armature through a closed opening from the outside, the invention inverts the approach by providing an elongated hole that is open at the end of the first leg, allowing the armature to be inserted directly into the bobbin assembly before mounting the entire unit to the yoke. This reversal of the assembly sequence simplifies the process while maintaining structural security.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The invention segments the assembly process into distinct steps: first assembling the bobbin with the armature inside through the elongated hole, then mounting this pre-assembled unit to the yoke. This segmentation allows the complex threading operation to be performed on a smaller, more manageable sub-assembly rather than attempting to thread the armature through the complete assembled structure.

Inventive Principle:
Principle #1Segmentation

2Ease of manufacture

If the armature has a uniform diameter, then the structure is simple to manufacture, but the magnetic release force is insufficient

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidmagnetic release force
Core Design Contradiction:
Ease of manufactureVSForce

Solution Approach 1:

The invention applies local quality by providing a stepped armature with different diameters in different sections. The first section has a larger diameter to maximize magnetic release force where the magnetic field acts most strongly, while the second section has a smaller diameter to allow clearance for the tether spring and to reduce material usage. This localized variation in diameter optimizes both magnetic performance and manufacturing efficiency.

Inventive Principle:
Principle #3Local quality

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

This design simplifies the assembly process and enhances the magnetic release force, enabling stronger attraction at equal currents compared to non-stepped armatures.

Implementation Method 1

a coil with a coil winding, an armature and a coil former are arranged between which a coil with coil winding, an armature and a coil former are arranged

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

the larger diameter section inside the coil for increased magnetic force

Methodology Applied
Scientific EffectMagnetic force: Magnetism

Data Source

PatentEP2096656B1Switching device
Publication Date: 2015.04.08 ABB AG(DE)
  • EP2096656B1 patent drawingFigure 1~2
  • EP2096656B1 patent drawingFigure 3~4
  • EP2096656B1 patent drawingFigure 5

AI summary

The invention relates to a switching device, in particular a motor protection switch, with a magnetic release with a yoke (50) which has a U-shaped first section (51) with a first leg (52) and a leg (53) running parallel to it, between which a coil with a coil winding, an armature (80) and a coil body (57) are arranged, wherein the armature (80) passes through an opening (62), and with a restraint spring (38) which is connected to the free end of the armature (80) outside the first leg (52). The opening (82) is designed as an elongated hole (82) open to the free end of the first leg (52), so that the coil with the coil body (57) can be inserted or is inserted into the elongated hole (82) in the direction of the longitudinal extension of the first leg (52) towards the U-shaped bridge (51) connecting the two legs (52, 53), with the armature passing through the elongated hole.