Cylinder Lock Secondary Element Shear Line Alignment
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Solution Overview
Problem
Traditional cylinder locks with primary pin assemblies and secondary locking elements face challenges in creating multiple shear lines effectively, leading to potential security vulnerabilities.
Innovation Solution
The lock design creates multiple shear lines by integrating a secondary locking element (SE) that interacts with primary pin assemblies, using a key with specific bitting surfaces and clearance cuts to align the SE and primary pin assemblies at the shear line, allowing rotation of the plug within the housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional primary pin assemblies are used to block rotation, then the basic locking function is achieved, but security vulnerabilities remain due to insufficient shear line complexity
Solution Approach 1:
The patent merges the secondary locking element with the primary pin assembly structure, where the SE is positioned within the plug and interacts with the same shear line as the primary pins. This integration allows multiple locking mechanisms to work together through a single unified structure, enhancing security without proportionally increasing overall device complexity
Solution Approach 2:
The locking mechanism is segmented into distinct functional components: primary pin assemblies for basic blocking, secondary locking elements for additional security, and control features for key interaction. Each segment operates independently but contributes to the overall security system, allowing the shear line to be blocked at multiple points simultaneously
2Reliability
If secondary locking elements are added to block rotation, then security is enhanced, but the device complexity increases
Solution Approach 1:
The secondary locking element is nested within the plug structure, positioned inside the cylindrical cavity. The SE is surrounded by the plug walls and interacts with features on the inner surface of the plug, creating a compact nested arrangement that maximizes security functionality within limited space without adding external complexity
Solution Approach 2:
The secondary locking element serves multiple functions: it blocks rotation at the shear line, interacts with control features on the key, and works in conjunction with the primary pin assemblies. This multi-functionality allows a single additional component to provide enhanced security without requiring multiple separate mechanisms
3Reliability
If multiple shear lines are created, then resistance to picking is improved, but manufacturing precision requirements increase
Solution Approach 1:
The control features are pre-formed on the key during key manufacturing, with precise positions and geometries established beforehand. These control features guide the secondary locking element to the correct position when the key is inserted, eliminating the need for complex alignment procedures during lock assembly and reducing manufacturing precision requirements for the lock itself
Data Source
AI summary
A cylinder lock includes tumbler pin assemblies and a secondary locking element associated with at least one of the pin assemblies. The secondary locking element is biased outwardly to engage a locking feature formed in the bore of the housing to prevent the plug from rotating within the bore. A portion of the associated primary pin assembly extends through the secondary locking element and into the keyway and is movable independently of the secondary locking element. The secondary locking element includes at least one control feature that is directly or indirectly engaged by a key inserted into the keyway to cause the secondary locking element to move inwardly toward the plug so that the secondary locking element disengages from the locking feature or to permit the secondary locking element to be moved inwardly toward the plug so that the secondary locking element can disengage from the locking feature.