Ball Differential Power Reserve Indicator for Mechanical Watches
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Solution Overview
Problem
The power reserve indication in mechanical watches is uncommon due to the need for substantial modifications and space consumption, making its generalization difficult, especially in smaller watch movements.
Innovation Solution
A power reserve display device using a coaxial ball differential mechanism integrated directly onto the barrel of a clockwork motor, which includes a ratchet, a differential plate, and an output wheel, allowing for efficient space utilization and minimal modifications to existing movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a power reserve indicator is added to a mechanical watch movement, then the functionality is improved, but the device complexity and space requirements increase substantially
Solution Approach 1:
The patent combines the power reserve indicator mechanism with the existing barrel assembly by integrating the differential mechanism directly onto the barrel shaft. The first input of the differential is connected to the barrel shaft while the second input connects to the barrel drum, merging the indication function with the existing power storage structure rather than adding a separate independent mechanism.
Solution Approach 2:
The differential mechanism is nested within the existing barrel assembly structure. The balls of the differential are positioned between the barrel drum and the differential plate, with the output wheel nested within the barrel assembly. This nesting allows the power reserve indicator to be housed within the existing movement space without requiring substantial external modifications.
2Adaptability or versatility
If a power reserve indicator is added to a mechanical watch movement, then the functionality is improved, but the space consumption increases
Solution Approach 1:
The patent utilizes the axial dimension of the barrel assembly by positioning the differential mechanism in the axial direction between the barrel drum and the ratchet. The balls are arranged in a radial pattern around the barrel shaft, effectively using the cylindrical space available in the existing movement layout rather than requiring additional lateral space.
Solution Approach 2:
The differential mechanism is nested within the existing barrel assembly structure. The balls of the differential are positioned between the barrel drum and the differential plate, with the output wheel nested within the barrel assembly. This nesting allows the power reserve indicator to be housed within the existing movement space without requiring substantial external modifications.
3Measurement precision
If a complex differential mechanism is used for power reserve indication, then the measurement precision is improved, but the manufacturing cost and complexity increase
Solution Approach 1:
The patent extracts only the essential differential function needed for power reserve indication, using a simplified ball differential mechanism rather than a complete planetary gear system. The differential plate connects directly to the ratchet through friction means, and the output wheel is simplified to indicate power reserve without requiring complex additional transmissions or indication mechanisms.
Solution Approach 2:
The patent employs a friction connection between the ratchet and the differential plate instead of a permanent mechanical engagement. This friction means allows for easier manufacturing and assembly while providing sufficient functionality for power reserve indication, reducing the need for precision-machined permanent connections.
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
This solution provides an inexpensive and space-efficient power reserve display that can be easily integrated into mechanical timepieces, reducing the axial height and volume requirements, while maintaining the functionality of the power reserve indication.
Implementation Method 1
a differential, coaxial with the barrel, of which a first input is driven indirectly by said ratchet and of which a second input is said drum, and of which the output is a pivoting output wheel, coaxial with said shaft... said differential comprises balls arranged to drive housings of said output wheel forming a basket
Implementation Method 2
said differential comprises balls arranged to drive housings of said output wheel forming a basket, and cooperating with an upper surface of said barrel and with a lower surface... of a differential board, which board is arranged to pivot on said shaft, coaxial with it, and is connected to said ratchet by a friction means
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A clockwork motor (10) with a barrel enclosing a spring mounted between a drum (14) and a shaft (11) pivotally fixed to a ratchet (21), comprising a differential (20) coaxial with the barrel, with a first input driven by the ratchet (21), a second input which is the drum (14), and a pivoting output wheel (23), coaxial with said shaft (11), arranged to constitute or drive a power reserve indicator, this differential (20) comprising balls (25) driving the output wheel (23), cooperating with an upper surface (13) of the drum (14), and with a lower surface (26), which faces it, of a differential board (22) constituting the first input, pivoting coaxially on said shaft (11) and connected to the ratchet (21) by a friction (24) cooperating with a plate (2), and the ratchet (21) constitutes the cover of the barrel.