Split-Seconds Device with Epicycloidal Train for Timepiece
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Solution Overview
Problem
Conventional split-seconds mechanisms in chronograph watches suffer from precision rate variations, increased complexity, and risk of damage due to friction and repeated hammer strikes on fine axes, which complicates the measurement of intermediate times without interrupting main timekeeping.
Innovation Solution
A split-seconds device with a differential mechanism that uses a planetary system to drive or block the split-seconds hand, reducing rate precision differences between operating and stopped states, and incorporating a spacer wheel and intermediate wheel to redirect hammer strikes and display time differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional split-seconds gripper mechanism is used, then the split-seconds hand can be stopped and restarted, but friction between the split-seconds lever and core causes rate precision variations
Solution Approach 1:
The patent introduces a differential mechanism as an intermediary between the power source and the split-seconds pinion. This differential includes a mobile input connected to the power source, a first mobile output connected to the split-seconds pinion, and a second mobile output. The control lever blocks the second mobile output, allowing the first mobile output to be driven by the input through the differential's satellite gears, thereby eliminating direct friction between the control lever and split-seconds core while maintaining operational control.
2Measurement precision
If an isolator mechanism is provided to raise the split-seconds lever when the clamp is closed, then friction is reduced, but the mechanism becomes complicated and expensive
Solution Approach 1:
The differential mechanism serves multiple functions simultaneously: it transmits power from the source to the split-seconds pinion, eliminates friction between the control lever and core, and provides a robust structural framework. This multi-functionality replaces the need for separate isolator mechanisms, reducing overall complexity while maintaining precision.
3Ease of operation
If fine axes with hearts are used for chronograph hands, then the split-seconds hand can be re-synchronized, but repeated hammer strikes increase the risk of damage
Solution Approach 1:
The differential mechanism acts as an intermediary that transmits the re-synchronization impulse from the control lever through the satellite gears to the split-seconds pinion. This indirect transmission through the differential's gear system reduces the impact forces compared to direct hammer strikes on fine axes, thereby improving reliability while maintaining operational capability.
4Adaptability or versatility
If a conventional split-seconds mechanism is implemented, then intermediate time measurement is enabled, but the overall device complexity considerably increases
Solution Approach 1:
The patent merges the power transmission function and the split-seconds control function into a single differential mechanism. The mobile input, mobile outputs, and control lever are integrated into one compact assembly that performs both timekeeping power transmission and split-seconds hand control, thereby reducing overall device complexity while maintaining the intermediate time measurement capability.
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 solution provides a robust, cost-effective, and reliable split-seconds mechanism that minimizes adverse effects on timepiece precision, simplifies the structure, and adds functionality for displaying time differences between split-seconds and chronograph hands.
Implementation Method 1
A split-seconds device with a differential mechanism that uses a planetary system to drive or block the split-seconds hand
Implementation Method 2
The use of a differential makes it possible to simultaneously and relatively easily reduce the difference in rate precision of conventional split-seconds mechanisms between their operating state and their stopped state
Data Source
AI summary
A split-seconds device with epicycloidal train for a timepiece. The device includes a split-seconds pinion which carries a fly-back hand and is mounted to rotate freely about a rotation arbor of the timepiece; a differential having an entry wheel adapted to be kinematically connected to a power source of the timepiece; a first exit wheel kinematically connected to the entry wheel by a planetary wheel and meshing with the split-seconds pinion; a second exit wheel kinematically connected to the entry wheel by the planetary wheel; and a control lever allowing to block either the first exit wheel or the second exit wheel, such that whichever of the first and second exit wheels is released by the control lever is adapted to be driven by the entry wheel when the latter is kinematically connected to the power source of the timepiece, thus allowing to block or respectively release the fly-back hand.