Cylinder Lock Key Permutations via Axial Stop Surfaces
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Solution Overview
Problem
Existing cylinder lock and key systems face limitations in achieving a high number of permutations for secure key combinations, making them vulnerable to unauthorized key production and access control in complex master key systems.
Innovation Solution
The introduction of cooperating stop surfaces on the keys and plugs, with multiple axial positions for first and second stop surfaces, allows for a significant increase in possible permutations by requiring precise alignment for correct key insertion, enhancing security and complexity, while maintaining backward compatibility with existing systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of pin or disc tumblers is increased to increase permutations, then security is improved, but device complexity increases
Solution Approach 1:
The patent introduces a new dimension for creating permutations by positioning stop surfaces at different axial locations along the key blade, rather than relying solely on increasing the number of tumblers. This dimensional approach allows multiple stop surface combinations (first stop surface at one axial position, second stop surface at another axial position) to generate diverse key codes without adding more tumblers, thereby increasing security while maintaining manageable device complexity
2Reliability
If the pitch between code heights is decreased to increase permutations, then security is improved, but manufacturing precision requirements increase
Solution Approach 1:
Instead of decreasing the pitch between code heights which would demand higher manufacturing precision, the patent creates additional permutation possibilities by utilizing the axial dimension along the key blade. Multiple stop surfaces can be positioned at different axial locations, providing another degree of freedom for code variation without compromising manufacturing tolerances or requiring tighter precision controls
3Ease of manufacture
If traditional single stop surface configuration is used, then ease of manufacture is maintained, but the number of possible permutations is limited
Solution Approach 1:
The key blade is segmented into multiple stop surfaces (first stop surface and second stop surface) positioned at different axial locations, each capable of contacting corresponding surfaces on the plug. This segmentation allows each stop surface to independently contribute to the code configuration, multiplying the total number of possible permutations while maintaining a manufacturing process that is an extended version of traditional single-stop-surface keys
Solution Approach 2:
The patent extends the traditional single-point stop surface concept into a multi-point axial distribution along the key blade. By positioning stop surfaces at different axial coordinates, the system creates a new dimension for code variation, significantly increasing the permutation space without fundamentally changing the manufacturing approach or requiring complex multi-dimensional machining
Data Source
AI summary
A cylinder lock and key system. The plugs comprise a housing having a cylindrical bore; and a cylindrical plug which is rotatable and which exhibits a front end and a keyway. The keys comprise a key bow; and a key blade is rotatable about the rotational axis when inserted. The plugs and keys are provided with cooperating stop surfaces for defining the fully inserted position of the keys. At least one first stop surface is in contact with a corresponding second stop surface when a key is inserted in the keyway of a lock. At least two first stop surfaces of each key are arranged adjacent each other and at least two second stop surfaces of each lock are arranged adjacent each other, at or in proximity to the keyway. A cylinder lock and key combination, a key, a key blank and a cylinder lock are also disclosed.