Cylinder Lock Retaining Pin Prevents Intrusion After Breakage
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Solution Overview
Problem
Existing cylinder locks with breakable notches are vulnerable to further intrusion after breakage, as remaining tumbler pins can be easily tampered with, allowing unauthorized access.
Innovation Solution
A cylinder lock design featuring mechanically weakened notches and a retaining pin system, where the retaining pin is positioned within the cylinder plug, slides out to maintain the cylinder plug in the housing, blocking further movement and intrusion, and additional hardened members prevent drilling and tampering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a mechanically weakened notch is provided in the cylinder lock for breakage, then the cylinder can be designed to break along a pre-determined line to prevent clamping tools from gripping the cylinder, but after breakage the remaining tumbler pins become easily accessible for further intrusion and tampering
Solution Approach 1:
The cylinder lock is divided into separable components: the cylinder plug with tumblers and the cylinder housing. The mechanically weakened notch allows the cylinder plug to be segmented from the housing upon breakage, but the retention pin ensures the segmented plug remains constrained within the housing, preventing access to tumblers while maintaining the breakage function.
Solution Approach 2:
The retention pin acts as an intermediary element between the cylinder plug and housing. It is positioned to engage with the cylinder plug after breakage, preventing the plug from being completely removed or tampered with, thus mediating between the breakage mechanism and the security function.
2Ease of operation
If the cylinder plug is completely removed or detached after breakage, then access to tumblers is enabled for easy unlocking, but if the cylinder plug remains retained, then the lock maintains security against further tampering
Solution Approach 1:
The retention pin is designed to be movable rather than fixed. It can be displaced by sufficient force to allow complete removal of the cylinder plug for legitimate unlocking operations, but returns to its retaining position under normal conditions to prevent tampering. This dynamic behavior allows the system to adapt between security and ease of operation modes.
Solution Approach 2:
The retention pin's position changes based on the applied force. Under normal operating conditions, the pin maintains the cylinder plug in a retained position for security. When sufficient force is applied during legitimate unlocking, the pin displaces to allow plug removal. This parameter change in the pin's position resolves the contradiction between security and ease of operation.
3Reliability
If additional retention mechanisms are added to prevent tampering after breakage, then security against intrusion is enhanced, but the device complexity increases
Solution Approach 1:
The retention pin serves multiple functions: it prevents complete removal of the cylinder plug after breakage, blocks access to tumblers, and can be displaced for legitimate unlocking operations. By making this single component multi-functional, the invention enhances security without requiring multiple separate retention mechanisms, thus minimizing the increase in device complexity.
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
Enhances security by preventing unauthorized access and tampering, ensuring the cylinder lock remains operational and secure even after a breakage attempt, with the retaining pin system effectively blocking the cylinder plug's movement and hardened members providing additional protection against drilling.
Implementation Method 1
said retaining pin being pre-stressed and displaceable under a spring force
Implementation Method 2
displaceable under a spring force
Implementation Method 3
mechanically weakened cylinder notch provided through at least part of the first cylinder half for forming a breakable tip portion
Implementation Method 4
additional hardened members prevent drilling and tampering
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention relates to a cylinder lock (10) comprising: a cylinder plug (30) having a keyway (35) adapted to receive a key; a longitudinally extending first cylinder half (23) and a second cylinder half (24); a rotatable cam (21) co-axial with and connected to the cylinder plug (30) for rotation therewith, the rotatable cam (21) being disposed externally of and between the first second cylinder halves (23, 24); a mechanically weakened cylinder notch (29) provided through at least part of the first cylinder half (23) for forming a breakable tip portion (28); a mechanically weakened plug notch (36) provided through at least part of the cylinder plug (30) for forming a breakable plug portion; a plurality of mutually aligned bores extending at right-angles to the cylinder plug axis and in which housing pins (52) which are substantially of equal length and plug pins (53) which are of different lengths are biased in the direction of the keyway (35) under spring force by a plurality of springs (51). said cylinder lock (10) further comprises at least one retaining pin (32), pre-stressed and displaceable under a spring force, provided at the cylinder plug (30) and depressed by a retaining member (31), said retaining pin (32) adapted to match at least partly with a corresponding retaining recess (27) formed at the first cylinder half (23) such that when the mechanically weakened cylinder notch (29) and plug notch (36) breaks away, said retaining member (31) slides out of the first cylinder half (23) and said retaining pin (32) maintains rest of the cylinder plug (30) in the first cylinder half (23) by matching with the retaining recess (27).