Balance Spring Softening Zones for Reduced Oscillation Eccentricity
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Solution Overview
Problem
Existing balance springs in watch movements exhibit eccentric development during oscillation due to their attachment to the ferrule and stud, leading to deviations in timekeeping accuracy.
Innovation Solution
A spiral spring with localized softening zones at specific turns, reducing the cross-section to minimize eccentricity by controlling the trajectory of the ends attached to the balance wheel and balance cock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flat balance spring with constant pitch is used, then the structure is simple and easy to manufacture, but the spring develops eccentrically during expansion and contraction, causing timekeeping deviation
Solution Approach 1:
The patent applies local quality by creating a variable pitch spiral spring where different sections have different pitch characteristics. Specifically, the spring has a first section with a first pitch and a second section with a second pitch different from the first, allowing different parts of the spring to serve different functional purposes in reducing eccentricity while maintaining overall structural simplicity
Solution Approach 2:
The patent changes the geometric parameter of pitch along the length of the spring blade. By varying the pitch from the first section to the second section, the spring achieves non-uniform winding characteristics that compensate for eccentric development during oscillation, thereby improving timekeeping accuracy without complicating the basic spring structure
2Manufacturing precision
If complex coil arrangements are implemented to reduce eccentricity, then timekeeping accuracy improves, but the device complexity increases
Solution Approach 1:
Instead of redesigning the entire spring structure, the patent applies local quality by modifying only specific sections of the spring blade. The variable pitch is implemented in targeted areas (first and second sections) while maintaining a relatively simple overall coil arrangement, thus reducing eccentricity without excessive complexity
Solution Approach 2:
The spring blade is segmented into multiple sections with different pitch characteristics. This segmentation allows each section to contribute differently to the spring's overall behavior during oscillation, enabling eccentricity reduction through controlled differential deformation rather than complex global restructuring
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 spiral spring closely follows its pinning points, significantly reducing eccentricity and improving the concentricity of the balance spring development, thereby enhancing timekeeping accuracy.
Implementation Method 1
a blade wound on itself between a first inner turn, intended to be attached to a ferrule attached to the axis of the balance wheel, and a last outer turn, intended to be attached to a stud attached to the balance cock, said blade having a constant or variable section
Data Source
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AI summary
The present invention relates to a spiral spring (1) intended to be associated with a balance wheel in a regulating organ of a watch movement and comprising a series of turns formed by a blade wound upon itself between a first inner turn (2) and a last outer turn (6), said blade having a constant or variable cross-section. Said blade comprises, on at least one of the first inner turn (2) and the last outer turn (6), at least one zone (e1, e2) of local softening centered approximately ¾ of a turn of said turn (2, 6) from its free end (2a, 6a), said zone (e1, e2) of local softening having a cross-section smaller than the cross-section of the blade in the vicinity of said zone (e1, e2) of local softening. The present invention also relates to a regulating organ comprising a balance wheel and such a spiral spring (1), as well as a timepiece comprising such a spiral spring (1) or such a regulating organ.