Locking Cylinder Snap Ring Rotation Stop

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Solution Overview

Problem

Conventional locking cylinders face issues with precise alignment of the cylinder core when rotated back to the locking position, leading to over-tightening and blocking of tumblers, making key removal difficult due to manufacturing tolerances and movement play between components.

Innovation Solution

A snap ring is used in conjunction with the cylinder housing to form a rotation stop, limiting the cylinder core's rotation angle to a predetermined range, ensuring precise alignment and preventing over-tightening by engaging in a free space on the housing, thus allowing key removal only in defined positions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the cylinder core is allowed to rotate freely when a key is inserted, then the key can be turned by any number of turns, but the cylinder core may be slightly over-turned causing misalignment of core bores with housing bores, blocking tumblers and preventing key removal

Engineering Contradiction:
Improvekey rotation freedomVSAvoidalignment precision of core bores with housing bores
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

A rotation stop is provided that limits the rotation angle of the cylinder core to a predetermined range before the key can be fully inserted and operated. This preliminary limitation prevents over-rotation that would cause misalignment of core bores with housing bores, ensuring tumblers remain properly positioned and the key can be removed after operation.

Inventive Principle:
Principle #10Preliminary action

2Adaptability or versatility

If manufacturing tolerances and play in downstream locking mechanism are present, then the lock components can accommodate variations, but the intended rotation angle range of the cylinder core is not exactly maintained

Engineering Contradiction:
Improvetolerance accommodationVSAvoidrotation angle precision
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The rotation stop provides a predetermined angular limitation that is established before the cylinder core engages with the downstream locking mechanism. This ensures that even with manufacturing tolerances and play in the locking mechanism, the cylinder core rotation angle remains within the intended range, maintaining precise alignment of tumblers with housing bores throughout operation.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3812537B1Locking cylinder
Publication Date: 2023.09.13 ABUS AUGUST BREMICKER SOEHNE KG
  • EP3812537B1 patent drawingFigure 1
  • EP3812537B1 patent drawingFigure 2
  • EP3812537B1 patent drawingFigure 3

AI summary

The present invention relates to a locking cylinder with a cylinder housing and a cylinder core rotatably mounted in the cylinder housing about a cylinder axis, the cylinder core being secured against axial movement relative to the cylinder housing by means of a snap ring, wherein the cylinder core has a keyway for inserting an associated key, wherein the cylinder core can be rotated between a locked position and an unlocked position by means of the inserted key, and wherein the locking cylinder has several tumblers that can be actuated by means of the associated key. In the locking cylinder according to the invention, the snap ring, together with the cylinder housing, forms a rotation stop for limiting the rotation angle of the cylinder core to a predetermined range.