Rhomboid Cross-Section Balance Spring for Watch Movement
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Solution Overview
Problem
Existing balance springs for mechanical watches have limitations in stress distribution and precision due to their rectangular cross-section, which affects the uniformity and accuracy of timekeeping.
Innovation Solution
A balance spring with a rhomboid winding cross-section, featuring diagonals of different lengths and angles, optimized for stress distribution and self-centering, allowing for precise adjustment of spring rate and simplified manufacturing through ceramic materials and selective laser ablation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rectangular cross-section is used for the balance spring, then the manufacturing is simpler, but the stress distribution and oscillation stability are insufficient
Solution Approach 1:
The patent applies asymmetry by changing the balance spring cross-section from a symmetric rectangular shape to an asymmetric rhomboid shape. The rhomboid cross-section has different diagonal lengths (first diagonal shorter than second diagonal) and different internal angles, creating an asymmetric geometry that optimizes stress distribution during oscillation while maintaining manufacturability through precise geometric definition
Solution Approach 2:
The patent employs parameter changes by specifically defining the rhomboid cross-section parameters: the relationship between the two diagonals (first diagonal shorter than second diagonal), the internal angles at different corners, and the overall dimensions. These parameter specifications transform the generic rectangular cross-section into a precisely controlled rhomboid shape that achieves optimal stress distribution and oscillation stability
2Measurement precision
If the balance spring geometry is optimized for precise timekeeping, then the clocking precision improves, but the manufacturing complexity increases
Solution Approach 1:
The asymmetric rhomboid cross-section with specifically defined diagonal relationships and angle variations provides the geometric optimization needed for precise clocking. The asymmetry creates favorable stress distribution patterns that improve oscillation stability and timekeeping precision while the geometry remains definable through straightforward dimensional parameters
Solution Approach 2:
By precisely controlling the rhomboid cross-section parameters (diagonal lengths, internal angles, and overall dimensions), the patent achieves optimal clocking precision. The parameter definitions provide a clear manufacturing target that balances geometric complexity with manufacturability, allowing precise timekeeping without excessive manufacturing difficulty
3Adaptability or versatility
If a rhomboid cross-section with specific diagonal relationships is used, then the spring rate can be precisely adjusted, but the manufacturing precision requirements increase
Solution Approach 1:
The patent enables precise spring rate adjustment through parameter changes in the rhomboid cross-section geometry. By varying the diagonal lengths (maintaining the relationship that the first diagonal is shorter than the second diagonal), internal angles, and overall dimensions, manufacturers can precisely tune the spring rate to achieve desired clocking characteristics
Solution Approach 2:
The asymmetric rhomboid geometry provides additional degrees of freedom for spring rate adjustment compared to a symmetric rectangular cross-section. The different diagonal lengths and angle variations at different corners create multiple geometric parameters that can be independently optimized to achieve precise spring rate control
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 rhomboid geometry enhances stress distribution and oscillation stability, enabling precise timekeeping and simplified production, with ceramic materials providing precise spring properties and versatile manufacturing options.
Implementation Method 1
The balance spring (1) is produced from an unmachined part (10) which is made of a ceramic material and is structured by a selective laser ablation method, such that the desired winding cross section is achieved.
Data Source
AI summary
The present invention relates to a balance spring for a mechanical movement of a watch, wherein the balance spring is embodied as a spiral spring and has a winding cross section. It is provided according to the invention that the winding cross section of the spiral spring is in the shape of a rhombus, wherein the rhombus has four sides, two first corners with a first internal angle, two second corners with a second internal angle, a first diagonal, connecting the two first corners to one another, and a second diagonal, connecting the two second corners to one another, the first diagonal being shorter than the second diagonal, and the first internal angle being larger than the second internal angle.