Radial Ball Differential for Compact Watch Power Reserve
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Solution Overview
Problem
Conventional axial power reserve indicators in mechanical watches are bulky and difficult to integrate into various movement designs, posing risks of deformation and breakage due to excessive stress.
Innovation Solution
A compact ball differential with a central core, inner ring, and ball cage featuring three toothed wheels with parallel axes, allowing for radial entry, exit, and blocking functions, and incorporating a clamping cone subjected to mechanical stress by a spring element for preload, enabling a flat and compact construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an axial power reserve indicator system is used, then the power reserve indication function is achieved, but the device becomes bulky and difficult to integrate into watch movements
Solution Approach 1:
The patent transitions from an axial system to a radial system by arranging the three toothed wheels and ball bearing in a radial configuration around a central axis. The ball bearing with four contact points is positioned radially, allowing the differential mechanism to occupy a compact circular footprint rather than extending axially, thereby reducing the overall device volume while maintaining the power reserve indication function.
Solution Approach 2:
The patent integrates multiple functions into a single compact differential unit. The three toothed wheels (entry, exit, and blocking) are combined with the ball bearing assembly into one unified radial structure, eliminating the need for separate axial components and reducing the overall device volume while maintaining all necessary differential functions.
2Reliability
If an axial differential system is used, then the differential function is achieved, but the system generates constructive disadvantages including risk of deformation and breakage
Solution Approach 1:
By changing from an axial to a radial configuration, the patent distributes mechanical stresses more evenly across the four contact points of the ball bearing. The radial arrangement allows forces to be applied perpendicular to the axis, reducing bending moments and shear stresses that cause deformation and breakage in axial systems, thereby improving component durability.
Solution Approach 2:
The patent employs a ball bearing with four specifically positioned contact points arranged radially around the central axis. This local configuration optimizes the distribution of mechanical loads at each contact point, ensuring that stresses are evenly distributed and preventing concentration of forces that would lead to deformation or breakage of individual components.
3Adaptability or versatility
If a compact radial design is implemented, then the device becomes easy to integrate into movements, but the complexity of the toothed wheel arrangement increases
Solution Approach 1:
The patent designs the three toothed wheels (entry, exit, and blocking wheels) with identical radial configurations and the same number of teeth. This universal design allows any of the three wheels to potentially serve multiple functions depending on the operating condition, simplifying the overall design while maintaining the ability to integrate into various movement configurations. The symmetry and uniformity of the radial arrangement make the device adaptable to different entry points and movement layouts.
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 compact, low-maintenance power reserve indicator with radial inlets and outlets, reducing the risk of wear and allowing for easy integration into watch movements, with interchangeable toothed wheels and a gear ratio range of 0.45 to 1.24, ensuring reliable operation without external forces.
Implementation Method 1
said bearing preferably comprises a spring element arranged to exert a mechanical stress on said clamping cone
Implementation Method 2
a spring element arranged to exert a mechanical stress on said clamping cone
Data Source
Figure 1
AI summary
The differential has a ball bearing (11) with four contact points comprising a central core (12), inner ring (15) and a ball cage (14). The central core includes a gear teeth (12c) driving a toothed wheel (20), and the inner ring includes a gear teeth (15c) driving a toothed wheel (21). The ball cage includes a gear teeth (14c) driving a toothed wheel (22). Each of the toothed wheels is identical and arranged for ensuring input, output and blocking function of the differential. The toothed wheels have axes parallel to axis of the ball bearing.