Electromagnetic Safety Switch Layout for Compact Locking

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Solution Overview

Problem

Conventional safety switches with a lock function using an electromagnet and a magnetizable member are larger in size, and the shape of the electromagnet has not been sufficiently optimized.

Innovation Solution

The safety switch design includes a compact electromagnet configuration with strategically placed attachment points and magnetic field line optimization, allowing for a downsized structure without compromising detection accuracy or attractive force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a safety switch is equipped with a lock function using an electromagnet and a member to be magnetized, then the lock function is achieved, but the size of the safety switch increases

Engineering Contradiction:
Improvelock functionVSAvoidsafety switch size
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The attachment portion for fixing the safety switch to the installation place is integrated directly into the electromagnet structure, merging two functions (locking and attachment) into a single component. This eliminates the need for separate attachment structures, thereby reducing the overall size of the safety switch while maintaining the lock function.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The electromagnet serves multiple functions: it provides the lock function by attracting the member to be magnetized, and simultaneously serves as the attachment portion for fixing the safety switch to the installation place. This multi-functionality reduces the number of separate components needed, contributing to size reduction.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Volume of moving object

If the electromagnet shape is optimized for compactness, then the safety switch size is reduced, but the magnetic field distribution and attraction force may be compromised

Engineering Contradiction:
Improveelectromagnet sizeVSAvoidattraction force
Core Design Contradiction:
Volume of moving objectVSForce

Solution Approach 1:

The electromagnet is designed with a specific shape where the attraction surface is positioned to optimize magnetic field distribution. The local geometry of the electromagnet structure is tailored to concentrate and direct the magnetic field effectively toward the member to be magnetized, ensuring sufficient attraction force despite the reduced overall size.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The electromagnet utilizes its depth dimension (in the direction of attraction) to maximize magnetic field strength within a compact footprint. By optimizing the depth and surface area relationship, the electromagnet achieves effective attraction force in a smaller overall volume.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 downsized safety switch maintains effective lock functionality while improving detection sensitivity and reducing interference between components, ensuring reliable operation and efficient use of space.

Implementation Method 1

an electromagnet on which an attraction surface corresponding to the surface to be attracted is formed

Methodology Applied
Scientific EffectElectromagnetism: Electromagnet

Implementation Method 2

a drive control unit that drives the electromagnet to cause the attraction surface of the electromagnet and the surface to be attracted of the actuator to be attracted to each other

Methodology Applied
Scientific EffectMagnetic attraction: Magnetism

Data Source

PatentEP4321790B1Safety switch
Publication Date: 2026.04.08 KEYENCE CORP
  • EP4321790B1 patent drawingFigure 1
  • EP4321790B1 patent drawingFigure 2
  • EP4321790B1 patent drawingFigure 3

AI summary

A safety switch (100) that has a lock function using an electromagnet and a member to be magnetized (300) is downsized. The safety switch includes: a detection unit that detects that a movable actuator is within a predetermined range; a safety signal output unit that outputs a safety signal based on a detection result obtained by the detection unit; an electromagnet; a lock input unit that receives a lock instruction for locking movement of the actuator; a drive control unit that drives the electromagnet based on the lock instruction received via the lock input unit; and an attachment portion which is formed on the electromagnet and fixes a switch body (200) to an installation place of the switch body.