Sensor Assembly Tamper-Proof Groove Locking Mechanism

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Solution Overview

Problem

Existing sensor arrangements lack sufficient security against manipulation and captiveness, particularly in meeting the safety requirements of the Machinery Directive, as they do not provide adequate form-fitting attachment to the functional unit and sufficient manipulation security.

Innovation Solution

A sensor arrangement with a locking device that is form-fittingly accommodated in the groove-like recess of a functional unit, featuring a covering device to prevent unauthorized access and manipulation, ensuring secure positioning and attachment through a combination of form-fitting and positive locking mechanisms, including a locking device with a coupling area for tool engagement and elastically deformable latching lugs for non-detachable locking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a sensor housing is fixed to a functional unit using conventional mounting methods, then the sensor arrangement can be installed, but it lacks sufficient security against manipulation and captiveness

Engineering Contradiction:
Improvesecurity against manipulationVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The locking device is segmented into distinct functional components: a locking body with form-fitting means for lateral engagement, a separate locking screw for axial securing, and an integrated coupling area for tool engagement. This segmentation allows each component to perform its specific function efficiently while maintaining overall system reliability against manipulation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The locking device is designed with a nested structure where the locking screw is integrated into the locking body, and the coupling area is incorporated within the locking device assembly. This nesting reduces the number of separate components while maintaining the complex security functions required for manipulation protection.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Reliability

If a locking device with form-fitting means is used to secure the sensor housing, then security against displacement is improved, but access to the coupling area becomes vulnerable to unauthorized manipulation

Engineering Contradiction:
Improvesecurity against displacementVSAvoidunauthorized manipulation
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The coupling area serves as an intermediary element that requires tool engagement for operation. By designing this interface to require specific tools (screwdrivers, Allen keys, etc.), the system mediates between the locking function and unauthorized access prevention, as casual manipulation without the appropriate tool is ineffective.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The form-fitting means are designed to engage in grooves or slots that prevent lateral displacement before the locking screw is fully tightened. This preliminary anti-action secures the sensor housing against displacement during installation and operation, while the subsequent locking screw engagement provides additional security against unauthorized manipulation.

Inventive Principle:
Principle #9Preliminary anti-action

3Device complexity

If non-positive bracing is used instead of form-fitting locking, then device complexity is reduced, but security against displacement along the longitudinal axis deteriorates

Engineering Contradiction:
Improvelocking mechanism complexityVSAvoidsecurity against displacement
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The locking screw is extracted as a separate, simple component from the locking body, allowing the form-fitting means to handle lateral positioning while the locking screw provides dedicated axial securing. This extraction simplifies the overall design compared to integrated complex locking mechanisms while maintaining high security against displacement.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The form-fitting means perform preliminary positioning and lateral securing of the sensor housing in the groove-like recess before the locking screw is engaged. This preliminary action establishes the correct position and prevents lateral displacement, while the subsequent locking screw engagement secures the assembly against axial displacement, achieving high reliability with relatively simple components.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2447546B1Sensor assembly
Publication Date: 2016.11.30 FESTO AG & CO KG
  • EP2447546B1 patent drawingFigure 1~6
  • EP2447546B1 patent drawingFigure 2~4
  • EP2447546B1 patent drawingFigure 3~8

AI summary

The arrangement (1) has a sensor housing (2) that is formed to provide retainer in groove-like recess (6). A sensor unit is provided for determining operating condition of function unit (5). The sensor housing is fastened toward longitudinal axis (7) of groove like-recess of function unit. A closure unit (21,29) is provided to fasten a locking device (3) in groove like-recess of function unit along longitudinal axis. A cover device is provided for covering a coupling region (31) to prevent unauthorized tool.