Striking Timepiece Gear Train With Lash Compensation
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Solution Overview
Problem
Striking mechanisms in timepieces, particularly classic repeating striking mechanisms, face challenges in mounting and synchronizing snails with the timepiece display due to complex kinematic connections, leading to issues with strike synchronization and hand positioning.
Innovation Solution
A mechanism with a geared connection between two cannon pinions, incorporating a lash-compensation device using a spring and notching to ensure synchronized striking and display, featuring a first and second cannon pinion with a geared connection, a third wheel, and a lash-compensation device that applies a return force to maintain precise meshing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a minutes snail is fixed directly to a cannon pinion to ensure synchronization, then the striking mechanism achieves accurate synchronization with the minute hand position, but the mounting and setting of the snails becomes complex and difficult
Solution Approach 1:
The invention introduces an intermediate cannon pinion (second cannon pinion) that separates the direct connection between the minutes snail and the first cannon pinion. This segmentation allows the minutes snail to be mounted on the intermediate pinion, which is then connected to the first cannon pinion through a geared connection, simplifying the mounting process while maintaining synchronization accuracy through the gear ratio relationship.
Solution Approach 2:
The second cannon pinion acts as an intermediary element between the first cannon pinion and the minutes snail. This intermediate component facilitates the transmission of motion while enabling independent mounting and adjustment of the snail, thereby reducing the complexity of direct mounting while preserving the synchronization function.
2Ease of manufacture
If a geared connection is used between cannon pinions to simplify mounting, then the ease of mounting improves, but lash in the geared connection causes loss of synchronization and energy loss
Solution Approach 1:
The spring element is pre-loaded to apply a continuous return force on the gearwheels, creating preliminary tension that prevents the development of lash (backlash) in the geared connection. This preliminary anti-action counteracts the tendency for gaps to form between meshing teeth, eliminating the source of energy loss and synchronization errors before they can occur during operation.
Solution Approach 2:
The spring element introduces a dynamic pre-loading mechanism that continuously adjusts the contact force between the gearwheels. This dynamic force ensures that the gear teeth remain in firm contact throughout the rotation cycle, adapting to variations in load and maintaining consistent meshing without the energy losses associated with rigid, fixed-preload systems.
3Manufacturing precision
If a spring element is used to compensate for lash, then the synchronization accuracy improves, but the device complexity increases
Solution Approach 1:
The spring element modifies the force parameter in the geared connection, transforming it from a passive, lash-prone connection to an actively pre-loaded connection. By changing the force parameter through spring pre-loading, the system achieves improved synchronization precision without requiring complex control mechanisms or multiple additional components.
Solution Approach 2:
The spring element automatically compensates for lash and maintains optimal gear meshing without requiring external adjustment mechanisms or complex control systems. The spring's inherent elastic properties enable it to self-adjust to variations in gear wear, thermal expansion, and load changes, maintaining synchronization precision through its own mechanical characteristics rather than through complex external control.
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 mechanism simplifies the fitting of cams and ensures synchronized striking with the timepiece display, improving alignment and reducing energy loss through precise meshing, thereby enhancing the operational efficiency and autonomy of the timepiece.
Implementation Method 1
a device (16) for compensating for the lash in the geared connection, the device (16) being arranged in such a way as to apply a return force returning the first and second wheels (14, 15) against: the opposite flanks of at least one tooth of the third wheel (21)
Data Source
AI summary
The mechanism (100) for a striking timepiece includes a first, and a second cannon pinions, a geared connection (14,15,21) between the first (1) and second (2) cannon pinions, and—a device (16) for compensating clearance in the geared connection. The geared connection (14,15,21) includes a first gear (15) attached to the first cannon pinion (1),—a second gear (14) mounted pivotably relative to the first cannon pinion, and—a third gear (21) attached to the second cannon pinion (2). The first and second gears mesh with the third gear, and the clearance compensation device (16) in the geared connection is arranged so as to exert a return force from the first and second gears against the opposing faces of at least one tooth of the third gear (21) and/or—the adjacent faces of at least two consecutive teeth of the third gear (21).