Padlock Recess and Projection Shim Block Mechanism
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Solution Overview
Problem
Combination padlocks are susceptible to direct mechanical attacks, such as the use of padlock shims, which can release the shackle without using a key or entering the authorized combination.
Innovation Solution
The padlock design incorporates recesses and projections on the passage and leg, which cooperate to block the insertion and rotation of a shim, preventing the preloaded locking member from being pushed back into its unlocked position, thereby enhancing security against mechanical attacks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a preloaded locking member is used to engage the notch and secure the shackle, then the ease of operation is improved, but the susceptibility to mechanical attacks worsens
Solution Approach 1:
The passage is segmented into multiple sections with recesses and projections that create distinct functional zones. The recesses and projections divide the passage into segments that work together to prevent shim insertion while maintaining the preloaded locking mechanism's operation, thus resolving the contradiction between ease of operation and security against mechanical attacks
Solution Approach 2:
The recesses and projections act as intermediary elements between the shackle and the locking member. These intermediaries block the direct path that a shim would need to take to push back the locking member, while still allowing the legitimate locking and unlocking operations to proceed, thus maintaining ease of operation while preventing mechanical attacks
2Device complexity
If the passage and leg are designed with a simple ring-shaped gap, then the device complexity is reduced, but the security against mechanical attacks worsens
Solution Approach 1:
Instead of uniformly modifying the entire passage structure, the invention applies local quality changes by introducing recesses and projections only in specific locations where they are most effective at blocking shim insertion. This localized approach enhances security against mechanical attacks while minimizing the increase in device complexity
Solution Approach 2:
The recesses and projections create an asymmetric internal structure within the passage that is specifically designed to prevent the symmetric rotation of a shim. This asymmetric geometry blocks the harmful action of shim insertion while maintaining the necessary symmetric functionality for legitimate locking operations, thus improving security without excessive 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
The design effectively impedes the use of padlock shims, providing a higher degree of security by blocking the ring-shaped gap and preventing the locking member from being pushed back, thus securing the shackle in its locked position.
Implementation Method 1
The locking member is preloaded towards the locked position by a spring
Data Source
AI summary
A padlock comprises a lock body including at least one passage defined therein. A shackle is displaceable between open and secured positions. The shackle has at least one leg which is slideable within the at least one passage and which includes a notch. A locking member is accommodated within the lock body and is displaceable between unlocked and locked positions. The locking member is preloaded towards the locked position to engage the notch to inhibit movement of the shackle from the secured position into the open position. One of the at least one passage and the at least one leg defines at least one recess. The other one of the at least one passage and the at least one leg defines at least one projection that extends into the at least one recess.