Split Retractor Assembly for Cylindrical Lockset Overtorque Protection
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Solution Overview
Problem
Conventional cylindrical locksets are vulnerable to overtorquing attacks, which can compromise the security of the lock by forcing the outer retractor to rotate beyond its normal limits, potentially leading to latch operation and lock compromise.
Innovation Solution
A cylindrical lockset design featuring a split retractor assembly with an inner cam-activated retractor and an outer cam-activated retractor, where the outer retractor is rendered inoperative during an overtorquing attack through a blocker assembly, ensuring the inner retractor remains functional to retract the latch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single retractor assembly is used in conventional cylindrical locksets, then the structure is simple and easy to manufacture, but the lock becomes vulnerable to overtorquing attacks that can force the retractor to rotate beyond normal limits and compromise security
Solution Approach 1:
The retractor assembly is divided into two independent but cooperatively functioning retractors: an inner retractor and an outer retractor. Each retractor has its own cam-activated mechanism and can independently retract the latch. This segmentation allows the system to maintain security even when one retractor is compromised by overtorquing attacks, as the other retractor remains functional.
2Ease of operation
If the outer retractor is made operative to retract the latch independently, then the ease of operation is improved, but the vulnerability to overtorquing attacks increases as the attacker can force the outer retractor to rotate beyond normal limits
Solution Approach 1:
The design incorporates a preliminary protective measure where the inner retractor is positioned and configured to prevent overtorquing attacks from affecting the outer retractor's ability to retract the latch. The inner retractor acts as a protective barrier that limits the rotational force transmitted to the outer retractor, thereby preventing the outer retractor from being forced beyond its normal operational limits while still allowing normal latch retraction operations.
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 design effectively thwarts overtorquing attacks by preventing the outer retractor from moving into a latch-retracting position, maintaining lock security even under excessive torque attempts, thus ensuring the latch can still be retracted by the inner handle.
Implementation Method 1
Inner and outer spindles having retractor activation cams are configured to bear upon cam surfaces of the inner and outer cam-activated retractors to retract the latch
Data Source
AI summary
A retractor assembly for a cylindrical lockset comprises inner and outer retractors. Each of the retractors has a cam engaging surface to convert rotary motion from the inside door handle into linear latch-retracting motion. Inner and outer spindles having retractor activation cams are configured to bear upon cam surfaces of the inner and outer retractors to retract the latch. When the inner door handle is operated, the inner retractor acts directly upon the tailpiece of the latch bolt assembly to retract the latch. When the outer door handle is operated, the outer retractor presses on the inner retractor, causing it to retract the latch. If there is an attack, a blocker assembly engages with members formed in the outer retractor to render the outer retractor inoperative to move into a latch-retracting position without interfering with operation of the inner retractor to move into a latch-retracting position.