Clock Hairspring with Varying Cross-Section Geometry
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Solution Overview
Problem
Achieving isochronism in mechanical clock oscillators is challenging due to the difficulty in maintaining precision, particularly with the quality of the spiral spring, and existing designs require lengthy experimentation to define suitable parameters for concentric development of the hairspring.
Innovation Solution
A balance spring design with a specific geometry, featuring a continuous ribbon with varying curvilinear sections and a seventh segment, allowing for excellent concentricity in expansion and contraction, and made from materials like silicon or diamond, ensuring improved chronometry without twisting or change in concavity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a traditional hairspring design is used, then the manufacturing process is simpler, but the concentricity and chronometry precision are insufficient
Solution Approach 1:
The hairspring is divided into multiple curvilinear sections (first through sixth sections) with different geometric characteristics. Each section has specific radius of curvature variations and thickness profiles that differ from the others, allowing precise control of the spring's elastic behavior and concentric development during operation.
Solution Approach 2:
Different sections of the hairspring blade have locally optimized properties: the first section has decreasing section with specific curvature, the second has constant section, the third has increasing section, and subsequent sections follow specific geometric patterns. This local differentiation ensures optimal elastic response and concentricity throughout the spring's range of motion.
2Manufacturing precision
If the hairspring blade rigidity is made uniform, then the manufacturing is easier, but the isochronism and timing precision deteriorate
Solution Approach 1:
The hairspring is designed with dynamically optimized geometric properties that vary along its length. The radius of curvature and blade thickness are adjusted in each section to compensate for elastic deformation patterns, ensuring that the spring maintains isochronous behavior across its entire operating range despite the complexity of the varying geometry.
3Reliability
If the hairspring is made with twisting or change of concavity, then certain mechanical properties may be improved, but the behavior in service and manufacturing precision are worsened
Solution Approach 1:
Instead of using twisting or changes in concavity to achieve desired mechanical properties, the invention inverts the approach by using a flat hairspring with carefully controlled variations in radius of curvature and blade thickness. This flat execution with controlled geometric variations achieves reliable service behavior while maintaining manufacturing precision and avoiding the complexities of twisted or non-flat configurations.
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 design enhances the precision and reliability of timepieces by ensuring better behavior and easier manufacturing, allowing for versatile applications in watches and pocket watches with improved rigidity and reduced length adjustment needs.
Implementation Method 1
a balance spring design with a specific geometry, featuring a continuous ribbon with varying curvilinear sections
Data Source
Figure 1
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AI summary
Spiral (1) comprising, tangent to each other: - a first inner coil at a first central angle (α1) and with a decreasing cross-section in a first ratio (R1); - a second coil at a second central angle (α2) and with a constant cross-section; - a third coil at a third central angle (α3) and with an increasing cross-section in a third ratio (R3); - a fourth coil at a fourth central angle (α4) and with a constant cross-section; - a fifth coil at a fifth central angle (α5) and with an increasing cross-section in a fifth ratio (R5); - a sixth coil at a sixth central angle (α6) and with an increasing cross-section in a sixth ratio (R6). In a variant, a seventh, more rigid segment deviates from said sixth coil. Movement (100) comprising this spiral (1). Watch (200) comprising this movement (100).