Mortise Lock Single Rosette Design via Offset Spindles
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Solution Overview
Problem
Conventional mortise locks for sanitary rooms require two rosettes or a long plate, which does not match the design of other interior doors, and incorporating a locking mechanism into a rosette results in a thicker rosette, disrupting visual uniformity and potentially damaging the door if modifications are made.
Innovation Solution
A mortise lock design where the axis of rotation of the second nut is positioned 21.5 mm below the first nut, allowing for a single rosette installation without additional door modifications, using standard parts and plastic components for cost-effectiveness, with a part-cylindrical recess and projection for enhanced locking and a pawl for force distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a locking mechanism is incorporated into a rosette, then a single rosette is sufficient for both handle and locking lever, but the rosette becomes considerably thicker, disrupting visual uniformity with other doors
Solution Approach 1:
The locking lever is repositioned from the traditional rosette location to a lower position on the door, utilizing the vertical dimension. The second nut is positioned at a standard distance of 21.5 mm below the first nut, allowing the locking mechanism to be mounted below the handle rosette rather than within it, thus maintaining a thin, uniform appearance while still providing locking functionality.
2Reliability
If conventional locks for sanitary rooms are used, then locking functionality is provided, but two rosettes or a long plate are required, which do not match the design of other interior doors
Solution Approach 1:
The lock case is designed to accommodate both the handle and locking lever through a single standardized mounting structure. The first nut (at position 19 mm) and second nut (at position 21.5 mm) share the same mounting plate, allowing the lock to function as both a handle mechanism and a locking mechanism, replacing the need for separate rosettes or long plates used in conventional sanitary room locks.
3Length of stationary object
If the lock case is made shorter to reduce material usage, then production costs are reduced, but the locking lever may not have sufficient engagement with the latch
Solution Approach 1:
The locking lever is pre-positioned at a fixed distance (21.5 mm below the first nut) during manufacturing, ensuring proper engagement geometry is built into the component design. This preliminary positioning of the second nut at the correct offset ensures that when installed, the locking lever will correctly engage the latch mechanism without requiring a longer lock case, thus maintaining both compact size and reliable engagement.
Data Source
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AI summary
The mortise lock has a first spindle (13) for receiving a handle (17') and a second spindle (20) for receiving a locking lever. The first spindle (13) is kinematically connected to a latch (21), and the first spindle (13) can be blocked by the second spindle (20). According to the invention, the axis of rotation of the second spindle (20) is arranged at a standard distance of 21.5 mm below the axis of rotation of the first spindle (13), so that standard parts for the lock case can be used. Preferably, the second spindle (20) is made of plastic. To keep the pressure on the second spindle (20) low when a blocked handle is actuated, the first spindle (13) can have a partially cylindrical recess (28) into which the second spindle (20) engages with a corresponding partially cylindrical projection (29) for blocking.In order to enable the second nut to be operated with both a locking lever and a key (37), the second nut (20) has a substantially square recess (32) for receiving a square pin, wherein a groove (34a-d; 35a-b) is provided on at least one side surface (33).