Tamper-Resistant Window Lock Cam Mechanism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional sash window locks are not tamper-resistant, allowing unauthorized access by enabling manipulation of the cam from the exterior, which compromises the security of sliding sash windows.
Innovation Solution
A tamper-resistant window lock design featuring a housing, shaft, cam, lever member, and compression spring, where the cam is pivotally mounted and configured to rotate 50 degrees before unlocking, with a unique recess and opening system that requires specific alignment to operate, preventing unauthorized operation from the outside.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the cam is mounted on the exterior surface of the housing for easy operation, then the ease of operation is improved, but the vulnerability to external tampering increases
Solution Approach 1:
The cam is nested within the housing cavity rather than being exposed on the exterior. The cam can still perform its locking function by engaging the keeper through the housing wall, but its rotational operation is protected from external tampering by being positioned inside the housing structure.
Solution Approach 2:
A shaft acts as an intermediary mechanism between the exterior operating element and the cam. The shaft transmits rotational motion through the housing wall to operate the cam internally, allowing external access while maintaining internal protection against tampering.
2Device complexity
If a simple cam and keeper mechanism is used, then the device complexity is reduced, but the reliability against unauthorized access decreases
Solution Approach 1:
The locking mechanism is segmented into distinct functional components: the cam for locking action, the keeper for engagement, the shaft for motion transmission, and the housing for protection. This segmentation allows each component to be optimized for its specific function while maintaining overall system reliability.
Solution Approach 2:
The cam features asymmetric shaped openings (first and second shaped openings at different positions) that require specific alignment with corresponding features on the shaft. This asymmetric design prevents unauthorized operation from the exterior while maintaining reliable operation from the interior.
3Ease of operation
If the cam can be operated from the exterior, then the ease of operation is improved, but the loss of information regarding unauthorized operation increases
Solution Approach 1:
The shaped openings in the cam and corresponding features on the shaft create a feedback mechanism where proper alignment is required for operation. This alignment requirement provides feedback that helps distinguish between authorized operation (with proper alignment) and unauthorized tampering (without proper alignment).
Data Source
AI summary
A tamper-proof lock includes: a housing, shaft/handle, cam, lever, spring, and plate. The shaft is pivotally mounted in a housing orifice, with the cam pivotally mounted to the shaft. The cam has first and second shaped openings at first and second respective radial positions, and an arcuate recess. The lever is secured to the shaft, and has a protrusion that alternately engages each of first and second ends of the arcuate recess to respectively/selectively drive the cam to rotate/counter-rotate in first and second directions, into locked and unlocked cam positions. The spring biases the plate for a protrusion thereon to be respectively received within each of first and second shaped cam openings, when aligned therewith at those cam positions, and for a curved surface of the plate to be correspondingly received within first and second curved cam recesses, respectively, when aligned therewith, which facilitate withdrawal of the plate protrusion.