Electromagnetic Safety Switch Actuator Offset for Gap-Free Locking

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Solution Overview

Problem

Existing safety switches with electromagnetic lock mechanisms struggle to maintain close contact between the attracting surface and the surface to be attracted due to gaps, requiring strong housings to absorb impact and compromising design efficiency.

Innovation Solution

The actuator is offset towards the switch body side during door closure, ensuring the attracting surface and the surface to be attracted overlap without gaps, using an electromagnetic lock mechanism to achieve close contact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a safety switch with electromagnetic lock mechanism is used, then the door can be securely locked, but gaps between the attracting surface and surface to be attracted reduce locking reliability

Engineering Contradiction:
Improvelocking reliabilityVSAvoidcontact precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The actuator is preliminarily offset toward the switch body side before the door fully closes, ensuring that the attracting surface and surface to be attracted are pre-positioned to overlap without gaps when the door reaches the closed state, thereby guaranteeing reliable electromagnetic locking

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The offset amount of the actuator is optimized to achieve the best contact state between the attracting surface and surface to be attracted, transforming the contact condition from gap-prone to overlap-ensured, thereby improving both manufacturing precision tolerance and locking reliability

Inventive Principle:
Principle #35Parameter changes

2Strength

If strong housings are used to absorb impact from gaps, then structural strength is improved, but device complexity and weight increase

Engineering Contradiction:
Improvehousing strengthVSAvoidhousing structure
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The problematic gap that causes impact is eliminated by offsetting the actuator, thereby removing the need for robust impact-absorbing housings and simplifying the overall structure while maintaining strength where truly needed

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

By preliminarily positioning the actuator offset, the harmful impact during door closure is prevented before it occurs, eliminating the need for compensatory strong housings

Inventive Principle:
Principle #10Preliminary action

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 configuration ensures reliable close contact between the attracting surfaces, allowing for efficient operation without the need for robust housings to absorb impact, thus enhancing safety switch performance.

Implementation Method 1

the electromagnet is driven such that the actuator magnetized member is attracted to the electromagnet, thereby forming a door-locked state

Methodology Applied
Scientific EffectElectromagnetic attraction: Electromagnet

Data Source

PatentEP4321791B1Safety switch
Publication Date: 2025.09.03 KEYENCE CORP
  • EP4321791B1 patent drawingFigure 1
  • EP4321791B1 patent drawingFigure 2
  • EP4321791B1 patent drawingFigure 3

AI summary

The close contact between a surface to be attracted and an attracting surface when an openable and closable door is closed is established at a high level to form a state in which the surface to be attracted and the attracting surface overlap each other without a gap. An electromagnetic lock type safety switch includes an actuator including: a member to be magnetized on which a surface to be attracted corresponding to an attracting surface, formed on an electromagnet of a switch body, is formed; an actuator attachment portion for attaching the actuator to a movable portion (openable and closable door); and a movement mechanism supporting the member to be magnetized to be movable relative to the actuator attachment portion.