Door Lock Assembly Preventing Unauthorized Latchbolt Retraction
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Solution Overview
Problem
Existing door lock assemblies in large facilities or public buildings face challenges in preventing unauthorized retraction of the latchbolt, which can lead to unwanted door openings, particularly when users push directly on the latchbolt with their fingers.
Innovation Solution
A lock assembly design featuring a housing, control member, latchbolt, and locking member, where the locking member is configured to engage with the control member to prevent movement of the latchbolt in both directions, and an auxiliary latchbolt biases the locking member out of the engaged position when the door is open, ensuring secure operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a locking member is added to prevent unauthorized retraction of the latchbolt, then security is improved, but device complexity increases
Solution Approach 1:
The locking member is nested within the housing structure and integrates with the control member assembly. The locking member engages with the control member to prevent unauthorized retraction, while being contained within the existing housing boundaries, thus adding security without proportionally increasing overall device complexity
Solution Approach 2:
The control member serves as an intermediary between the locking member and the latchbolt. The control member translates the locking member's engagement state into corresponding latchbolt positioning, mediating the interaction between these components and allowing the locking mechanism to function without direct complex coupling between all elements
2Reliability
If the locking member prevents movement in both directions, then security is improved, but ease of operation deteriorates
Solution Approach 1:
The locking member is designed to be dynamically controllable, transitioning between locked and unlocked states based on control member position. The spring element provides dynamic biasing that assists the locking member in engaging or disengaging based on operational forces applied to the control member, making the system adaptive rather than statically fixed
Solution Approach 2:
The spring element performs preliminary action by biasing the locking member toward the engaged position before any unauthorized force is applied. This pre-positioning ensures that when the control member is in the retracted position, the locking member is already prepared to prevent latchbolt movement, reducing the operational steps needed to secure the door
3Reliability
If the locking member engages with the control member to prevent latchbolt movement, then security is improved, but device complexity increases
Solution Approach 1:
The locking member and control member are merged into a single functional assembly where the control member serves dual purposes: controlling latchbolt retraction and interfacing with the locking member. This combining of functions reduces the number of separate components needed, adding security while minimizing the increase in device complexity
Data Source
AI summary
A lock assembly for use with a door movably coupled to a door frame. The lock assembly includes a housing, a control member, a latchbolt, and a locking member. The control member is movably coupled to the housing from a locked position to an unlocked position to allow the door to move with respect to the door frame. The latchbolt moves with respect to the housing in a first direction and a second direction. The locking member is configured for engagement with the control member to move the locking member with respect to the housing into and out of an engaged position with respect to the latchbolt. The locking member includes a surface that contacts the latchbolt when the locking member is in the engaged position to substantially prevent movement of the latchbolt in the first and second directions.