Rekeyable Lock Cylinder Rack Mechanism for Bitting Variation

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Solution Overview

Problem

Existing rekeyable lock cylinders face challenges in maximizing the variation in key bitting positions while maintaining the strength of small components.

Innovation Solution

The design incorporates a rekeyable lock cylinder with a plug assembly and a key follower system that includes a rack with multiple engagement features, allowing for at least seven different bitting positions and enhancing security by increasing the number of possible key combinations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If sizes and tolerances of engaging components are reduced to allow increased variation in key bitting, then the number of bitting combinations is increased, but stress on the small components increases

Engineering Contradiction:

Improvevariation in key bittingVSAvoidstrength of components

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The lock mechanism is divided into separate modular components: a rack with multiple discrete engagement features (at least seven), a locking bar, and a key follower. This segmentation allows each component to be optimized independently - the rack can provide many bitting positions while the locking bar and follower maintain sufficient size and strength.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent transitions from traditional single-dimension key bitting to multi-dimensional engagement by providing at least seven different engagement features on the rack that can engage with the locking bar at different positions. This dimensional expansion increases bitting variation without requiring proportional reduction in component strength.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If the number of bitting positions is increased to maximize security, then the number of key combinations is increased, but the complexity of the engagement mechanism increases

Engineering Contradiction:

Improvesecurity of lock cylinderVSAvoidcomplexity of engagement mechanism

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Multiple engagement features are integrated into a single rack component rather than using separate mechanisms for each bitting position. The locking bar engages with this consolidated rack that contains all seven or more engagement features, simplifying the overall mechanism while maintaining high security through increased bitting positions.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The rack serves multiple functions simultaneously: it provides the locking interface, contains all engagement features for different bitting positions, and works with the key follower to translate key insertions into locking bar movement. This multi-functionality reduces the need for additional separate components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS20250101769A1Rekeyable lock with small increments

Publication Date: 2025.03.27 ASSA ABLOY AMERICAS RESIDENTIAL INC

AI summary

A rekeyable lock cylinder with a cylinder body and a plug assembly. The lock cylinder includes a plurality of key followers and a corresponding plurality of racks disposed in the plug assembly. Disengaging the racks from the key followers allows rekeying of the lock cylinder.