Coaxial Elastic Indexing Mechanism for Watch Time Zone Wheels
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Solution Overview
Problem
Timepiece display mechanisms, such as those for time zone and jumping hour wheels, face challenges due to significant space occupation, limited deflection values of spring elements, and unreproducible force variations caused by dimensional variations during production, leading to unreliable and uncontrolled indexing.
Innovation Solution
A timepiece indexing mechanism featuring a coaxial arrangement of an indexing element with elastic return means, comprising pairs of elastic arms that exert radial thrust forces to ensure precise and controlled indexing, reducing stress and eliminating force dispersion by using parallel elastic arms to achieve the desired torque and bending deflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spring elements are pushed to their maximum to achieve required deflection values, then indexing reliability improves, but the risk of element breakage increases and dimensional variations cause significant force variations
Solution Approach 1:
The indexing mechanism is divided into two independent coaxial elements: a first element with indexing means and a second element with indexing relief means. This segmentation allows each element to be optimized independently, reducing stress concentration and improving reliability without requiring excessive deflection from single spring elements.
Solution Approach 2:
The two indexing elements are arranged coaxially with one inside the other, creating a nested configuration. This nesting reduces the overall radial space required while maintaining the indexing function, allowing the mechanism to achieve required deflection values without pushing spring elements to their maximum strength limits.
2Adaptability or versatility
If multiple plates/pinions are connected by star/cam and spring elements to achieve indexing function, then indexing capability improves, but the thickness of the mechanism increases significantly
Solution Approach 1:
The indexing mechanism uses a nested coaxial arrangement where the first indexing element and second indexing element are positioned one inside the other about a common axis. This configuration achieves full indexing capability with minimal radial thickness, eliminating the need for multiple stacked plates and spring elements.
Solution Approach 2:
The indexing function is merged into a single coaxial interaction between two elements rather than requiring separate plates, pinions, and spring elements. The bearing surfaces and indexing means work together in a unified coaxial arrangement, reducing overall mechanism thickness while maintaining indexing versatility.
3Ease of manufacture
If dimensional variations occur during production, then manufacturing ease improves, but force variations become significant and unreproducible
Solution Approach 1:
The patent employs localized bearing surfaces with specific geometric profiles (e.g., conical, cylindrical, or spherical surfaces) that concentrate the interaction at well-defined contact points. This local quality approach ensures that force transmission occurs through predetermined geometric relationships, making the system less sensitive to overall dimensional variations and improving force reproducibility.
Solution Approach 2:
The indexing mechanism uses geometric parameters of the bearing surfaces (angles, radii, profiles) that can be precisely controlled during manufacturing. By optimizing these local geometric parameters, the system achieves reproducible force characteristics even when other dimensional parameters vary within normal manufacturing tolerances.
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 reduces the thickness of the mechanism, ensures reliable and precise indexing, minimizes the risk of spring element breakage, and maintains reproducible force values, thereby addressing the issues of space occupation and force variability.
Implementation Method 1
comprising elastic return means arranged to exert a substantially radial thrust force with respect to said axis on a said component in order to press it against said first bearing surface
Data Source
AI summary
A timepiece indexing element cooperating coaxially with a component including an indexing relief element defining indexing positions, including a first bearing surface cooperating in abutment with the component, elastic return device exerting a radial thrust on this component to press it onto this first bearing surface, and indexing device cooperating with the indexing relief element, these elastic return devices include at least a first elastic arm including a first indexing surface comprised in this indexing device and arranged to exert a radial thrust force on the component and, at least a second elastic arm arranged to exert a radial thrust force on the first elastic arm.