Snap-Action Switch Box Assembly With Orientation-Independent Torsion Spring

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Solution Overview

Problem

Existing snap-action switch boxes for disconnectors require additional electrical insulation due to metal components, complicating manufacture and assembly, and necessitate specific orientation of torsion springs, which slows production and requires special springs.

Innovation Solution

A snap-action switch box with reduced metallic elements, using polymeric materials for the rotating components and a single, orientation-independent torsion spring, simplifying assembly and eliminating the need for special springs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metal components are used inside the snap-action switch box, then structural strength and reliability are improved, but additional electrical insulation is required which complicates manufacture and assembly

Engineering Contradiction:
Improvestructural reliabilityVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes metal components from the snap-action switch box interior, extracting the problematic element that required insulation. The indexing element and other internal components are made from insulating materials, eliminating the need for additional electrical insulation while maintaining structural functionality.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the material parameter of internal components from conductive (metal) to insulating (polymer or composite). This material substitution eliminates electrical insulation requirements while preserving the mechanical and structural functions of the components.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If torsion springs are mounted in specific orientation, then proper functioning is ensured, but assembly time increases and production is slowed

Engineering Contradiction:
Improvefunctional reliabilityVSAvoidassembly speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent employs asymmetric indexing element geometry with protrusions positioned at specific angular locations (e.g., 0° and 180°). This asymmetric design creates a self-aligning mechanism where the indexing element naturally orients itself during assembly, eliminating the need for precise pre-orientation of the torsion spring and enabling faster assembly while ensuring proper function.

Inventive Principle:
Principle #4Asymmetry

3Device complexity

If a single torsion spring is used, then component count and cost are reduced, but the spring must be usable in either orientation which limits design options

Engineering Contradiction:
Improvecomponent countVSAvoidspring orientation flexibility
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent designs the indexing element with symmetric features (protrusions at opposite positions) that allow a single torsion spring to function correctly regardless of its mounting orientation. This universal design enables the same component to serve multiple orientation configurations, reducing part count while maintaining adaptability.

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 solution provides a reliable, easy-to-assemble, cost-effective switch box with improved manufacturing efficiency and reduced component count, utilizing a single torsion spring that can be mounted in either orientation.

Implementation Method 1

a spring which is mounted on the indexing element so that it can be loaded by a rotation of the loading spindle about the central axis

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4494174B1Snap-action switch box for rotatable electric contacts, particularly for disconnectors
Publication Date: 2026.01.28 BREMAS ERSCE
  • EP4494174B1 patent drawingFigure 1
  • EP4494174B1 patent drawingFigure 2a
  • EP4494174B1 patent drawingFigure 2b

AI summary

A snap-action switch box (10) comprising a base (14), a loading spindle (16), an indexing element (17) associated rotatably with both, and a helical torsion spring (12) which is mounted on the indexing element (17) so that it can be loaded by a rotation of the loading spindle (16) about a central axis (40a); the spring (12) has two stems which protrude from respective end turns of the spring (12) and the indexing element (17) comprises at least two abutments (71, 72) which protrude in an eccentric position and in opposite directions and are substantially parallel to the central rotation axis (40a), wherein the stems (12a, 12b) of the spring are adapted to abut respectively against the abutments (71, 72).