Magnetic Field Sensor for Access Protection Locking Detection

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Solution Overview

Problem

Conventional access protection devices face challenges in reliably detecting the locking status due to variations in component distances caused by temperature fluctuations and material settlement, making existing monitoring methods, such as light barriers and position switches, unsuitable for secure and accurate locking position detection.

Innovation Solution

A monitoring device equipped with a two-axis magnetic field sensor and transmitter, which detects changes in the magnetic field as the bolt moves between locking and unlocking positions, allowing for reliable position detection without contact and accommodating variations in component alignment, using either the sensor or transmitter on the bolt or in the lockable part.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If light barriers are used for monitoring the locking element position, then the locking status can be detected, but the detection becomes unreliable under pollution conditions

Engineering Contradiction:
Improvelocking status detection reliabilityVSAvoidpollution conditions
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces optical detection (light barriers) with magnetic field-based detection. The magnetic field sensor detects the position of the locking element through magnetic coupling, which is not affected by pollution, dust, or environmental conditions that interfere with optical systems. This substitution of detection principle eliminates the vulnerability to harmful environmental factors.

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

2Measurement precision

If position switches are used for detecting the locking element position, then the locking status can be detected, but the detection accuracy decreases due to distance variations from temperature fluctuations and material settlement

Engineering Contradiction:
Improveposition detection accuracyVSAvoidcomponent distance stability
Core Design Contradiction:
Measurement precisionVSStability of the object's composition

Solution Approach 1:

The patent replaces mechanical contact-based position switches with a non-contact magnetic field sensing system. The magnetic field sensor detects the position of the locking element through magnetic field interactions without requiring precise mechanical alignment or contact. This eliminates the sensitivity to distance variations caused by thermal expansion or material settlement, maintaining measurement precision under varying environmental conditions.

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

Solution Approach 2:

The system uses magnetic field strength as the detection parameter instead of mechanical position or optical alignment. The magnetic field sensor measures changes in magnetic field characteristics (such as field strength or flux) that correspond to the locking element position. This parameter change enables detection that is independent of physical distance variations, compensating for the instability of component spacing.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If conventional monitoring devices are used, then the locking status can be detected, but the component tolerances must be strictly observed and dirt regulations must not be undercut

Engineering Contradiction:
Improvedetection reliabilityVSAvoidcomponent tolerance requirements
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces conventional monitoring devices with magnetic field-based sensing that operates through non-contact detection. This substitution eliminates the need for strict component tolerances and clean room conditions, as magnetic fields penetrate non-magnetic materials and are not affected by contamination. The system becomes more robust and easier to install without requiring precise alignment or controlled environmental conditions.

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

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

Ensures accurate detection of the locking position by measuring both X and Y components of the magnetic field, providing a characteristic point that remains reliable even in the presence of external interference fields, thus ensuring secure operation of safety-relevant access protection devices.

Implementation Method 1

the magnetic field generator (32) generates a magnetic field which can act on the magnetic field sensor (31)

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Data Source

PatentEP2877658B1Access protection device and a method for monitoring a status of the access protection device
Publication Date: 2018.11.07 K A SCHMERSAL HLDG
  • EP2877658B1 patent drawingFigure 1~5

AI summary

The invention relates to an access protection device and a method for monitoring at least one status of the safety-relevant access protection device with a closable part (10) having an opening (11), a closing part (20) having a latch (21) which is movable between a locking position and unlocking position, wherein the latch (21) protrudes into the opening (11) in the locking position and the latch (21) is pulled out of the opening (11) in the unlocking position, and a monitoring device (30) for detecting at least one status of the access protection device, particularly a locking status, when the latch (21) is in the locking position. For this purpose, according to the invention the monitoring device (30) has a dual-axis magnetic field sensor (31) and a magnetic field transmitter (32) which are movable relative to one another, wherein the magnetic field sensor (31) or the magnetic field transmitter (32) is movable with the latch (21).