Eccentric Keyway Padlock Prevents Key Ejection
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Solution Overview
Problem
Existing key-actuated padlocks lack effective mechanisms to prevent unauthorized key removal and ejection, particularly in linear lock types where biasing forces can eject the key, compromising security.
Innovation Solution
A padlock with a uniquely formed keyway that has an eccentric profile, serving as both a rotational and axial stop, allowing the key to be removed only in a single position, thereby restricting key withdrawal and ejection, enhancing security by limiting key rotation and axial movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a linear lock type with biasing force is used, then the locking mechanism can be easily actuated, but the key can be unintentionally ejected
Solution Approach 1:
The keyway is designed with an asymmetric cross-sectional shape that does not match the key's profile except at specific positions. This asymmetry creates selective engagement: the key can be inserted and removed only when aligned with the keyway opening, but cannot be ejected at other rotational positions due to the mismatched geometry between key and keyway profiles.
Solution Approach 2:
The eccentric keyway profile acts as an intermediary mechanism between the key and the locking mechanism. It mediates key retention by providing geometric constraints that allow key insertion/removal only at specific orientations, while preventing ejection at other orientations through its asymmetric profile design.
2Ease of operation
If the key can be freely removed, then the lock operation is simple, but unauthorized key removal compromises security
Solution Approach 1:
The asymmetric keyway profile restricts key removal to specific authorized positions (when the keyway opening aligns with the key), preventing unauthorized removal at other positions. This geometric constraint ensures that even if someone attempts to remove the key, they can only do so when the locking mechanism is in the correct orientation.
Solution Approach 2:
The eccentric keyway design preemptively prevents unauthorized key removal by creating geometric barriers before such removal can occur. The asymmetric profile is configured to block key extraction except when the keyway is properly aligned, thereby preventing security compromises before they can happen.
3Ease of manufacture
If a standard keyway is used, then manufacturing is simple, but key rotation is not restricted
Solution Approach 1:
The keyway is designed with an asymmetric cross-sectional profile that naturally restricts key rotation to specific discrete positions. This asymmetric geometry provides built-in rotational control without requiring additional complex mechanisms, maintaining manufacturing simplicity while achieving the desired rotation restriction function.
Data Source
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AI summary
A padlock is configured to be locked and unlocked by a key and includes a lock body having an internal cavity with a locking mechanism and a keyway extending through the lock body into the internal cavity to provide access to the locking mechanism by the key. The locking mechanism is configured to be selectively moved over a range of positions when the key is received therein to lock and unlock the padlock. The keyway has an eccentric profile that permits the key to be removed from the locking mechanism in only a single position of the range of positions.