Watch Stem Extraction Mechanism With Stroke-Limited Pull Stud
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Solution Overview
Problem
Current watch mechanisms face challenges during dismantling and reassembly, as the winding stem extraction often results in disassembly of the movement, risking damage to neighboring components like the winding pinion teeth, and existing solutions are either costly or cumbersome.
Innovation Solution
A control mechanism with a stroke-limited pull stud, utilizing a limiter piston and bridge configuration that allows for easy extraction of the rod without damaging adjacent components, featuring alternative configurations such as a fixed head, threaded insertion, or elastic limiter piston to simplify assembly and disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a pull stud is used for stem extraction, then the stem can be removed, but the pull stroke is not limited and components may come out of housing
Solution Approach 1:
The patent applies preliminary action by pre-positioning a stop element within the bridge housing that limits the pull stroke of the pull stud before the rod can be completely extracted. This stop element is integrated into the bridge structure and automatically engages when the pull stud is pulled, preventing the rod and associated components from leaving the housing. The stop element creates a predetermined travel limit that ensures reliable component retention while still allowing stem removal.
2Object-affected harmful factors
If an oblong-shaped hole or groove is used to guide tool entry, then damage to winding pinion teeth is limited, but precise tool orientation is required and manufacturing cost increases
Solution Approach 1:
The patent extracts the tool guidance function from the bridge structure by providing a dedicated extraction opening in the case back that allows direct access to the pull stud. This separate opening is positioned and shaped specifically for tool insertion and orientation, removing the need for complex oblong holes or grooves to be formed in the bridge itself. The opening in the case back serves as the dedicated access path, simplifying the bridge structure while still protecting the winding pinion teeth from tool damage.
3Ease of operation
If a pull stud is screwed into the stem, then the pull stroke is limited, but excessive unscrewing still poses risks and manufacturing cost increases
Solution Approach 1:
The patent applies preliminary action by pre-positioning a stop element within the bridge housing that limits the pull stroke of the pull stud before the rod can be completely extracted. This stop element is integrated into the bridge structure and automatically engages when the pull stud is pulled, preventing the rod and associated components from leaving the housing. The stop element creates a predetermined travel limit that ensures reliable component retention while still allowing stem removal.
Data Source
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Figure 5~6
AI summary
Control mechanism (100) for clockwork movement, comprising, in a housing of a plate (1) comprising said mechanism (100), a control rod (10) movable in a longitudinal direction (D), said rod (10) comprising a groove (11) cooperating with a stud (20) comprising a pull tab (2) for pivoting operation on said plate (1) of said pull tab (2), which is held in position by a jumper (3), and said mechanism (100) comprising a bridge (5) cooperating with said plate (1) to enclose said rod (10). The said bridge (5) includes a housing (54) in which a limiting piston (6) is movable, arranged to bear against one end of a trunnion (29) which includes the said pull (2) under the application of a force in a transverse direction (T) substantially orthogonal to the said longitudinal direction (D), to allow the release of the said rod (10) after a given stroke (C) of the said limiting piston (6).