Lock Dead Bolt Lever Cut-Out Prevents Rotary Bit Jamming
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Solution Overview
Problem
Existing locks for hinged closure members, such as gates and doors, often experience issues with the rotary driving bit getting stuck due to high resistance during operation, leading to blocked locks and requiring technician intervention, and they have excessive leeway in the dead bolt's projection position, causing malfunctions.
Innovation Solution
A lock design with a cut-out portion between the first and second engaging portions on the dead bolt lever allows the rotary driving bit to pass through when unlocking, reducing the risk of getting stuck and minimizing leeway by using a separate guiding member with decreased manufacturing tolerance, and enhancing the lock's robustness with increased overlap between the rotary driving bit and second turn engagement portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the dead bolt is allowed to move with large leeway (up to 5 mm) in its projection position, then the lock can accommodate manufacturing tolerances and thermal expansion, but the dead bolt may not be properly caught in the striker leading to malfunctions
Solution Approach 1:
The patent introduces a retaining member with a slot that has specific dimensional parameters (width, depth, position) to control the dead bolt's movement. The slot's dimensions are carefully selected to limit the dead bolt's leeway to a precise range (0.5-2.0 mm) while still accommodating manufacturing tolerances. This parameter optimization ensures reliable engagement with the striker while preventing excessive movement that would cause malfunctions.
2Device complexity
If the rotary driving bit engages the dead bolt lever directly, then the lock structure is simple, but the rotary driving bit may get stuck between the dead bolt lever and the second turn latch bolt driver when resistance is high, blocking the lock
Solution Approach 1:
The patent introduces a second turn latch bolt driver as an intermediary component between the rotary driving bit and the dead bolt lever. This intermediary engages with the dead bolt lever through a cam mechanism, allowing the rotary driving bit to rotate without directly engaging the dead bolt lever. The intermediary absorbs the resistance and prevents the rotary driving bit from getting stuck, while maintaining a relatively simple overall structure.
3Length of moving object
If the dead bolt lever is designed with a long stroke to provide sufficient engagement, then the lock can accommodate larger tolerances, but the rotary driving bit may pass through the engagement portion when the dead bolt is not correctly locked, causing blockage
Solution Approach 1:
The patent applies local quality by creating a specific geometric feature (the engagement portion with a cam profile) at a precise location on the dead bolt lever. The engagement portion has a specific shape with a cam surface that contacts the rotary driving bit at a controlled angle. This localized geometric design ensures that the rotary driving bit engages properly only when the dead bolt is correctly locked, while allowing the lever to have sufficient stroke length for proper engagement without causing blockage.
Data Source
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AI summary
A lock (1) comprising: a frame (4); a dead bolt (3) slideably mounted on the frame; a dead bolt lever (37) pivotally mounted on the frame; a key-actuated cylinder (10); and a locking mechanism configured to lock the dead bolt. The locking mechanism having a predefined leeway and comprising: a spring-biased retaining member (25) comprising a slot having a catch; and a projecting element (27) on the dead bolt which extends into said slot. The catch is delimited by four edges with an inclined edge having an inclination of at least 60° and with an edge having a length of at most 1,5 times a diameter of a minimal bounding circle of the projecting element. The dead bolt lever has a cut-out portion allowing a rotary driving bit of the cylinder to pass an engaging portion for every dead bolt lever position within the predefined leeway. These measures reduce dead bolt leeway.