Flexible Pivot Structure for Low-Parasitic Watch Rotation
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Solution Overview
Problem
Flexible pivot components for watchmaking face issues such as parasitic movements affecting precision, sensitivity to gravity and linear accelerations, limited travel, non-linear torque, and manufacturing constraints, particularly in achieving isochronism and shock resistance.
Innovation Solution
A flexible pivot component with three links and intermediate rigid parts connected by slide and hinge joints, allowing rotation and radial translation, which minimizes parasitic movements and maintains symmetry to reduce gravity dependence, while enabling a planar shape and maximizing travel, and isostatic operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If elastic blades cross at a point located at 12.7% of their length to minimize parasitic displacements, then parasitic displacements are reduced, but the travel of the mobile rigid part is reduced
Solution Approach 1:
The patent transitions from a planar two-dimensional flexible pivot to a three-dimensional non-planar structure by introducing intermediate rigid parts that are not confined to the same plane as the elastic blades. This spatial arrangement allows the system to achieve both minimal parasitic displacements and adequate travel range by distributing movements across multiple dimensions.
Solution Approach 2:
The patent introduces intermediate rigid parts as intermediary elements between the support and the mobile rigid part. These intermediate parts, connected by elastic links, act as mediators that decouple the constraints on the virtual rotation axis from the travel limitations, allowing independent optimization of precision and travel range.
2Measurement precision
If the inertial moving part is divided into N rigid portions connected by N elastic coupling links, then parasitic displacements are minimized and overstressing is avoided, but thermal expansion management becomes more difficult and shock resistance degrades
Solution Approach 1:
The patent divides the flexible pivot into multiple discrete elastic links connecting intermediate rigid parts, rather than using a single continuous elastic structure. This segmentation allows each link to be independently optimized for stress distribution while maintaining overall structural integrity and shock resistance.
Solution Approach 2:
The patent employs composite construction by combining rigid intermediate parts with elastic connecting links, creating a hybrid structure that leverages the advantages of both rigid and elastic materials. This composite approach enables precise control of parasitic displacements while maintaining shock resistance through the rigid components.
3Ease of manufacture
If a monolithic planar flexible pivot is used, then manufacturing is simplified, but the structure cannot always be produced in a single plane and internal degrees of freedom increase
Solution Approach 1:
The patent moves from planar two-dimensional design to three-dimensional non-planar configuration, arranging elastic links and intermediate rigid parts in multiple planes. This eliminates the constraint of single-plane manufacturing while maintaining manufacturability through systematic spatial arrangement, and reduces internal degrees of freedom by constraining movements to the intended rotational path.
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 reduces parasitic movements and gravity sensitivity, enhances shock resistance, and improves isochronism by allowing clean rotation with minimal internal degrees of freedom, facilitating thermal management and impact resistance.
Implementation Method 1
a flexible pivot comprising at least three elastic links connecting, in parallel, the support and the movable rigid part... each elastic link comprising, in series, an elastic blade, an intermediate rigid part and a pair of parallel elastic blades
Data Source
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AI summary
The flexible pivot component comprises a support (300) and a movable rigid portion (301) suspended from the support (300) by a flexible pivot (351) arranged to guide the movable rigid portion (301) in rotation relative to the support (300) about a virtual axis of rotation (A). The flexible pivot (351) comprises at least three elastic joints (352, 353, 354) connecting, in parallel, the support (300) and the movable rigid portion (301). Each elastic joint (352, 353, 354) comprises, in series, a first elastic element (302, 303, 304), an intermediate rigid portion (308, 309, 310), and a second elastic element (305, 306, 307). The flexible pivot (351) further includes third elastic elements (315, 316, 317) each directly connecting an intermediate rigid part (308, 309, 310) to another.