Safety Switch Locking Pin Deformation to Prevent Unsafe Access

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Solution Overview

Problem

Existing safety switches for industrial machines and plants are prone to pin breakage or deformation under excessive stress, leading to unreliable operation and potential unsafe conditions due to undetected access openings.

Innovation Solution

A safety switch with a locking pin that plastically deforms without breaking when subjected to excessive stress, preventing the pin from moving to the unlocking position and ensuring safe access by maintaining the locking mechanism engaged, even in damaged conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional access control systems are used, then access functionality is provided, but the system is vulnerable to hacking and electrical failures

Engineering Contradiction:
Improvesystem reliabilityVSAvoidhacking vulnerability and electrical failure
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces electronic control systems with a mechanically-operated switch that uses physical key insertion and rotational motion to actuate a cam mechanism, which mechanically opens or closes electrical contacts. This mechanical substitution eliminates vulnerabilities to electronic hacking while maintaining access control functionality through purely mechanical operation.

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

2Object-affected harmful factors

If mechanical switches are used, then hacking resistance is improved, but the switch may be inadvertently operated by children or unauthorized persons

Engineering Contradiction:
Improvehacking resistanceVSAvoidinadvertent operation risk
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies different functional qualities to different parts of the switch mechanism: the outer housing and cam mechanism provide the mechanical access control function, while the inner chamber contains a magnetic seal assembly that provides selective magnetic field blocking. This local differentiation of functions allows the switch to resist both electronic hacking and inadvertent mechanical operation through the magnetic seal requirement.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent introduces a magnetic seal assembly as an intermediary mechanism between the mechanical key operation and the electrical contact actuation. The magnetic seal requires specific magnetic field interaction to open, serving as an additional layer of control that prevents inadvertent operation while maintaining the mechanical hacking resistance of the overall system.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If complex security mechanisms are added, then security is improved, but device complexity increases

Engineering Contradiction:
Improvesecurity against unauthorized accessVSAvoidswitch mechanism complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges multiple security functions into a single integrated switch mechanism: the mechanical key-operated cam provides physical access control, while the magnetic seal assembly provides additional security through magnetic field blocking. These functions are combined in one device rather than requiring separate systems, maintaining security while limiting the increase in overall device complexity.

Inventive Principle:
Principle #5Merging (Combining)

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 effectively prevents unsafe access by ensuring the locking pin remains engaged, preventing machine restart in unsafe conditions and reducing the risk of operational errors.

Implementation Method 1

a magnetically sealable opening in the switch housing having a perimeter defining the magnetically sealable opening

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Data Source

PatentEP4533506B1Safety switch for access control
Publication Date: 2026.05.06 PIZZATO ELETTRICA SRL
  • EP4533506B1 patent drawingFigure 1
  • EP4533506B1 patent drawingFigure 2
  • EP4533506B1 patent drawingFigure 3

AI summary

A safety switch for controlling the access to industrial machines or plants comprises a switching device (2) housing switching means and an actuator device (3) having an operating pin (8) to interact with the switching means upon the opening/closing of the access, a locking/unlocking mechanism (14) housed in the switching device (2) and provided with a locking pin (15) movable between a locking position and an unlocking position of the access, an operating pin (8) associated with the actuator device (3) to interact with the locking pin (15) to hold the actuator device (3) fastened to said switching device (2), which, in turn, houses a locking element with controlled deformation, mechanically connected to the locking pin (15) and sized to deform plastically upon the application on the locking pin (15) of a deformation stress higher than a predetermined threshold value.