Interchangeable Cylinder Lock with Segmented Plate

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Solution Overview

Problem

Existing interchangeable cylinder systems for furniture locks face difficulties in simple and reliable unlocking and enhanced security, as they often rely on leaf springs or leaf-shaped blocking elements that are challenging to disengage, leading to potential tampering and unauthorized removal.

Innovation Solution

A small plate designed as a blocking element, spring-loaded to engage in an annular groove, with a radial indentation bevel and a sickle-shaped locking collar, provides enhanced security and guided displacement, ensuring the lock cylinder can be removed only with a defined-width unlocking element, reducing axial play and tampering risks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a wire pin is inserted into the channel to push the leaf spring out of the groove, then the locking cylinder can be removed from the cylinder housing, but the operation is difficult to accomplish due to the freedom of movement of the leaf spring in the channel

Engineering Contradiction:
Improveease of unlockingVSAvoidreliability of unlocking
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The locking element is segmented into a plate-shaped body with a locking collar that engages the groove, allowing controlled disengagement. The plate is divided into functional zones: a locking collar for engagement, a chamfered region for controlled displacement, and a spring-loaded mounting area for resilient retention.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The unlocking element acts as an intermediary tool that engages the chamfered region of the plate to translate linear insertion motion into radial displacement of the locking collar out of the groove, mediating between the user and the locking mechanism.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If a leaf spring is used to secure the locking cylinder in the cylinder housing, then the locking mechanism is simpler, but the holding function is weaker and security is reduced

Engineering Contradiction:
Improvesimplicity of locking mechanismVSAvoidholding function
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The locking collar is formed with a curved, crescent-shaped cross-section that complements the annular groove geometry, creating a snap-fit engagement that provides strong holding force while maintaining simple plate construction.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The plate transitions from a flexible spring state during installation to a rigid locked state when the locking collar engages the groove, with the spring force providing initial retention and the geometric engagement providing mechanical strength.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If any wire pin can be inserted into the opening to push the leaf spring out, then the unlocking is more accessible, but unauthorized removal becomes easier

Engineering Contradiction:
Improveaccessibility of unlockingVSAvoidtampering risk
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The chamfer is localized to a specific region on the plate, creating a geometric key that only matches the corresponding feature on the authorized unlocking element, while the rest of the plate maintains its locking function with the groove engagement.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The plate design breaks symmetry by featuring a unilateral chamfered region rather than a symmetric structure, ensuring that only an unlocking element with the matching asymmetric geometry can disengage the locking collar from the groove.

Inventive Principle:
Principle #4Asymmetry

4Reliability

If the locking element is completely encapsulated in the cylinder housing, then security is significantly improved, but manufacturing and mounting become more complex

Engineering Contradiction:
ImprovesecurityVSAvoidease of manufacture and mounting
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The plate-shaped locking element serves multiple functions: it provides the locking collar for groove engagement, incorporates the chamfered region for controlled unlocking, and includes spring mounting features for resilient retention, all in a single encapsulated component.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The locking collar is extracted as a distinct functional feature from the plate body, allowing it to engage the groove independently while the plate remains mounted in the housing, enabling the locking function to be separated from the mounting structure.

Inventive Principle:
Principle #2Taking out (Extraction)

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 simplifies and secures the unlocking process by requiring a specific unlocking element width and providing a guided displacement mechanism, significantly improving the holding function and security of the lock cylinder within the cylinder housing.

Implementation Method 1

the locking element is spring-loaded in a locking position engaging in an annular groove

Methodology Applied
Scientific EffectSpring force: Spring

Implementation Method 2

the locking element has a chamfer on which the associated end, i.e. the tip of the unlocking element, is supported and, when the latter is pushed forward to unlock, pushes the locking element radially out of the annular groove

Methodology Applied
Scientific EffectMechanical force transmission through chamfer: Wedge

Data Source

PatentEP2623693B1An interchangeable cylinder lock system
Publication Date: 2019.10.02 MARTIN LEHMANN GMBH & CO KG
  • EP2623693B1 patent drawingFigure 1~2
  • EP2623693B1 patent drawingFigure 3~4
  • EP2623693B1 patent drawingFigure 5~6

AI summary

The system (1) has a cylinder housing (2) that is provided with a lock cylinder. The rod-shaped unlocking element (6) is inserted into an opening (36). The circumferential surface of lock cylinder is provided with an annular groove. An axial stop is held in the recess provided on collar. The locking element is held in the annular groove at locking position. The locking element is displaced from annular groove by the unlocking element at removing position such that lock cylinder is removed from cylinder housing.