Thermally Compensated Composite Balance Spring for Stable Oscillation
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Solution Overview
Problem
Horological movements face precision issues due to temperature-induced variations in the modulus of elasticity of flexible components, such as spiral springs, which affect the frequency stability of the movement.
Innovation Solution
A flexible horological component made of a composite material comprising a matrix with nanotubes or nanowires distributed parallel to each other, and a thermal compensation material within the matrix that has a thermoelastic coefficient of opposite sign to the other materials, thereby compensating for temperature-induced changes in the modulus of elasticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional materials are used for flexible components, then the component structure is simple, but the frequency stability deteriorates due to temperature-induced variations in the modulus of elasticity
Solution Approach 1:
The patent applies composite materials consisting of a matrix material combined with a thermal compensation material having a negative thermoelastic coefficient. This composite structure compensates for temperature-induced variations in the modulus of elasticity, thereby maintaining frequency stability of the oscillator mechanism while managing the increased structural complexity through controlled material composition.
Solution Approach 2:
The patent utilizes parameter changes by selecting materials with specific thermoelastic coefficients, particularly negative TEC materials, to counterbalance the positive TEC of conventional spring materials. This parameter-based approach enables the composite material to maintain a substantially constant effective modulus of elasticity across temperature variations, resolving the frequency stability issue.
2Reliability
If thermal compensation material is added to the composite, then the modulus of elasticity stability improves, but the manufacturing complexity increases
Solution Approach 1:
The patent employs a porous matrix structure that can accommodate thermal compensation material particles or fibers. This porous architecture facilitates the integration of negative TEC materials while maintaining the flexible component's mechanical properties, and the porous structure may also simplify manufacturing by allowing easy infiltration of compensation materials during the fabrication process.
Solution Approach 2:
The composite material design combines a matrix (which may be porous) with dispersed thermal compensation material in a controlled ratio. This composite approach enables tuning of the overall thermoelastic behavior while managing manufacturing complexity through established composite fabrication techniques such as infiltration, co-extrusion, or layer-by-layer assembly.
3Strength
If nanotubes or nanowires are used to reinforce the matrix, then the strength-to-weight ratio improves, but the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies particular parameters for nanotube or nanowire reinforcement, including diameter ranges (1-100 nm), length ranges (1-100 micrometers), and volume fractions (0.1-10%). By controlling these parameters, the patent achieves enhanced strength-to-weight ratio while managing manufacturing precision requirements through defined specification ranges that accommodate typical fabrication tolerances.
Solution Approach 2:
The porous matrix structure provides a framework that naturally guides and distributes nanotubes or nanowires during infiltration or growth processes. The porous architecture reduces the precision requirements for nanotube alignment by providing a structured environment that promotes uniform distribution, thereby achieving high strength-to-weight ratio without excessive manufacturing complexity.
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 component maintains its performance and frequency stability across varying temperatures, as the thermal compensation material inversely adjusts its modulus of elasticity to counteract changes in the other materials, ensuring consistent operation.
Implementation Method 1
the thermal compensation material having a thermoelastic coefficient of opposite sign to the other materials of the composite material, the variation of the modulus of elasticity of the compensation material occurs inversely to that of the deformation of the other materials of the component
Data Source
AI summary
A flexible horological component for an oscillator mechanism of a horological movement, the component extending along a principal plane (P) and including at least a part made of a composite material (1), the composite material (1) including a matrix (2) and a multitude of nanotubes or nanowires (3) distributed in the matrix (2), the nanotubes or nanowires (3) being juxtaposed and disposed substantially parallel with an axis (A) substantially perpendicular to the plane (P) of the component, the matrix including a flexible filling material (4) to fill the interstices between the nanotubes or nanowires (3), the filling material (4) comprising at least in part a thermal compensation material wherein the thermoelastic coefficient (TEC) is of the opposite sign to that of the other materials of the composite material (1).