Leaf Spring Lock Cylinder Key Retention Mechanism
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Solution Overview
Problem
Conventional lock cylinders often fail to provide secure locking and key retention mechanisms, especially in emergency situations, where only authorized personnel should be able to lock and unlock doors, and may not securely retain the key within the plug during operation.
Innovation Solution
A lock cylinder design featuring a shell, plug, locking member, and leaf spring, where the leaf spring is positioned to prevent key removal during rotation, with a check pin system that ensures the plug can only rotate when a proper key is inserted, and the leaf spring's unique shape allows for easy insertion but prevents removal once the key is fully inserted.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional lock cylinder is used, then the basic locking function is provided, but the key can be removed during operation and unauthorized access may occur
Solution Approach 1:
The leaf spring is nested within the plug structure, with its first portion positioned in the keyway and second portion extending to the recess. This nested configuration allows the leaf spring to function as an integrated key retention mechanism without adding external components, thereby improving key security while maintaining structural simplicity
Solution Approach 2:
The leaf spring acts as an intermediary element between the key and the locking mechanism. When the key is inserted, the leaf spring's tip engages with the key and is urged against the shell's inner surface by the tapered recess, creating a mechanical interlock that prevents key removal during operation without requiring direct key-to-locking-member contact
2Ease of operation
If a thumb-turn or similar interior locking apparatus is used, then any person can lock and unlock the door, but authorized access control is lost
Solution Approach 1:
The lock cylinder maintains the universal ability to be operated from the interior side of the door while requiring key insertion. The check pin system allows the plug to rotate when a proper key is inserted, enabling authorized personnel to lock and unlock the door, thus combining ease of operation with access control security in a single mechanism
3Ease of operation
If the plug can rotate freely, then the key can be easily inserted and removed, but key retention during operation cannot be ensured
Solution Approach 1:
The leaf spring provides a dynamic key retention mechanism that adapts during key insertion and rotation. When the key is inserted, the leaf spring's tip is urged against the shell's inner surface, preventing removal. During plug rotation, the tapered recess allows the leaf spring tip to move radially inward while maintaining contact, enabling rotation while retaining the key throughout the operational cycle
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 ensures secure locking and key retention, allowing authorized personnel to lock and unlock doors while preventing unauthorized access, with simplified assembly and reduced complexity, and compatibility with multiple keys within a key family for enhanced security.
Implementation Method 1
The leaf spring is positioned in the opening and includes a first portion extending radially inward toward the keyway and a second portion extending radially outward toward the recess. When a key is inserted, a tip of the second portion extends into the recess. When the plug is subsequently rotated, a tapered surface of the recess urges the tip radially inward and into contact with an inner surface of the shell.
Data Source
AI summary
A lock cylinder generally including a shell, a plug positioned within the shell, a locking member, and a leaf spring. The plug includes an opening which is aligned with a recess formed in the shell. The locking member is configured to selectively prevent rotation of the plug with respect to the shell. The leaf spring is positioned in the opening and includes a first portion extending radially inward toward the keyway, and a second portion extending radially outward toward the recess. When a key is inserted, a tip of the second portion extends into the recess. When the plug is subsequently rotated, a tapered surface of the recess urges the tip radially inward and into contact with an inner surface of the shell.