Flexure Bearing Ribs Minimize Anticlastic Curvature
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Solution Overview
Problem
Mechanical watch oscillators face precision limitations due to friction differences in balance pivots, which affect chronometric accuracy, and existing flexure bearings exhibit nonlinearity in response to bending angles, leading to errors in timekeeping.
Innovation Solution
A flexure bearing with a flexible strip featuring relief structures, such as ribs, is designed to minimize anticlastic curvature while maintaining elastic performance, ensuring isochronism and insensitivity to orientation and amplitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional balance pivots are used in mechanical watch oscillators, then the structure is simple and easy to manufacture, but friction differences occur according to different positions in space, limiting chronometric precision
Solution Approach 1:
The patent replaces traditional mechanical pivot-based support with a flexure bearing system. The flexible strip performs both the guiding function and elastic return force function simultaneously, eliminating pivot friction that caused position-dependent precision errors. This substitution of mechanical pivot system with flexible element system resolves the contradiction by achieving higher precision without proportionally increasing complexity.
Solution Approach 2:
The flexible strip in the flexure bearing performs multiple functions: it provides guiding constraints, generates elastic return force, and supports the inertia element. By consolidating these functions into a single component rather than separate pivots and springs, the design achieves improved precision while controlling overall structural complexity.
2Measurement precision
If flexure bearings are used to eliminate pivot friction, then chronometric precision improves, but nonlinearity in response to bending angles introduces errors in timekeeping
Solution Approach 1:
The patent applies relief structures (ribs) at specific locations on the flexible strip to modify local stiffness characteristics. These ribs are positioned to counteract anticlastic curvature in critical areas while maintaining flexibility where needed. This localized modification corrects the nonlinearity issue without compromising the overall flexure bearing functionality, thereby improving isochronism while maintaining timekeeping accuracy.
Solution Approach 2:
The patent modifies the physical parameters of the flexible strip by adding relief structures that change its bending characteristics. The ribs alter the strip's stiffness distribution and reduce anticlastic curvature, directly addressing the nonlinearity in bending response. This parameter modification enables the flexure bearing to maintain more linear behavior across different amplitude ranges, improving reliability and isochronism.
3Manufacturing precision
If the flexible strip is made stiffer to reduce deformation, then manufacturing precision improves, but the elastic return means becomes less effective and amplitude is reduced
Solution Approach 1:
The relief structures (ribs) are strategically positioned on the flexible strip to provide localized stiffness enhancement only where geometric precision is critical, while leaving other regions sufficiently flexible to maintain effective elastic return force. This selective stiffening approach allows the strip to achieve better manufacturing precision without sacrificing the elastic functionality needed for oscillator operation.
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 significantly reduces nonlinearity, enhancing the accuracy of mechanical watches by minimizing errors to less than 1 second per day and allowing for larger amplitudes without material stress, thereby improving chronometric precision.
Implementation Method 1
at least one flexure bearing forming an elastic return means for said inertia element in said resonator and comprising at least one flexible strip joining a first embedment of said first element to a second embedment of said second element
Implementation Method 2
said at least one strip extending substantially in the form of a ribbon around or on either side of a neutral geometric axis joining said first embedment and said second embedment, and comprising at least one median area extending transversely, along said second axis X, on either side of said neutral axis and whose thickness is a nominal thickness EN
Data Source
AI summary
A timepiece resonator including an inertia element suspended from a flexible strip deformable in a plane XY parallel to a longitudinal direction Y, and whose transverse extension along a transverse axis X, in projection onto the plane XY, is variable and of positive value on at least one side of the neutral axis (FN) of the strip, which includes, at a distance from its embedments, at least one rib extending substantially along an axis Z perpendicular to the plane XY, each having at least one generatrix which is farther from the neutral axis (FN) than the external surfaces of the sections of the strip located outside the ribs, and the longitudinal extension (LN) of each rib of the strip, along the longitudinal axis Y, is less than one fifth of the length L of the strip between its embedments.