Timepiece Movement Preload Control for Stable Isochronism
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Solution Overview
Problem
Existing constant force mechanisms in watch movements fail to maintain isochronism when integrated with additional disengageable mechanisms like chronographs, as torque requirements vary with the state of these additional mechanisms, leading to inconsistent torque supply to the regulating system.
Innovation Solution
A clockwork movement with a preload control system that modifies the prestress of the elastic element based on the state of the additional mechanism, ensuring isochronism by compensating for varying torque demands through a differential gear mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power take-off for the additional mechanism is arranged upstream of the constant force mechanism, then the state of the additional mechanism does not influence the torque supplied to the regulating system, but the frequency of rotational steps of the power take-off may be insufficient to operate the additional mechanism
Solution Approach 1:
The patent introduces an intermediary mechanism (the constant force mechanism with downstream power take-off) that mediates between the energy source and the additional mechanism. The constant force mechanism's output wheel provides both the regulated torque to the regulating system and the activated power to the additional mechanism, ensuring both torque stability and sufficient frequency
Solution Approach 2:
The patent inverts the conventional arrangement by placing the power take-off for the additional mechanism downstream of the constant force mechanism rather than upstream. This inversion allows the additional mechanism to be driven by the constant force output, ensuring both isochronism and adequate operational frequency
2Reliability
If the additional mechanism is located downstream of the constant force device, then isochronism can be maintained, but the torque requirement varies depending on the state of the additional mechanism
Solution Approach 1:
The patent makes the preload of the elastic element dynamic rather than fixed. The preload control system adjusts the prestress of the elastic element based on the state of the additional mechanism, allowing the system to adapt torque distribution dynamically while maintaining isochronism
Solution Approach 2:
The patent changes the parameter of elastic element prestress based on the operational state. When the additional mechanism is activated, the preload control system modifies the prestress parameter to compensate for varying torque demands, ensuring stable regulating system operation
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 preload control system maintains consistent torque supply to the regulating system by adjusting the prestress of the elastic element, thereby preserving isochronism even when additional mechanisms are activated.
Implementation Method 1
an elastic element subjected to prestressing and arranged to be periodically recharged as a function of the rotation of said output wheel
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a timepiece movement (1) comprising: - a mechanical energy source (3); - a constant-force device (7) comprising an input wheel (11), arranged to be driven by said mechanical energy source (3), as well as an output wheel (13) kinematically connected to said input wheel (11) via a resilient element (9), which is preloaded and arranged to be recharged periodically on the basis of the rotation of said output wheel (13); - a regulating system (5) arranged to be driven by said output wheel (13). According to the invention, said movement (1) comprises: - an activation mechanism (29) arranged to be driven by said output wheel (13) and to drive a supplementary mechanism (27); and - a preload control system (23) arranged to modify said preload of said resilient member (9) on the basis of the state of said activation mechanism (29).