Shaking force balancing of a 2-DOF isotropic horological oscillator
| Autor: | Etienne Thalmann, Hubert Schneegans, Simon Henein |
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Mechanical oscillator
0209 industrial biotechnology Crank Computer science 2-DOF Mechanism Isotropy Work (physics) 0211 other engineering and technologies General Engineering Compliant mechanisms 02 engineering and technology Displacement (vector) Finite element method Dynamic balancing 020901 industrial engineering & automation Quality (physics) Control theory Silicon flexures Mechanical watch Escapement Shaking force balancing 021106 design practice & management |
| Popis: | Despite centuries of research and significant advances, the escapement mechanism used to count and maintain oscillations of mechanical time bases remains a complex mechanism and a major source of energy losses. We showed in previous work that, instead of the widely used rotational one degree-of-freedom (DOF) oscillators, 2-DOF flexure oscillators have the potential of revolutionizing mechanical watchmaking by eliminating the traditional escapement, replacing it by a simple crank driving a pin. Additionally, using flexures increases the quality factor of the time base, leading to further potential improvements in timekeeping accuracy and energy consumption. However, a significant challenge of these new time bases is their balancing such that the influence of external accelerations on their frequency is minimized, a necessary condition for accurate timekeeping in portable applications. This article presents a novel 2-DOF planar flexure oscillator called Wattwins and demonstrates how it can be made insensitive to linear accelerations such as gravity. For this purpose, a new approach to shaking force balancing is developed based on the decomposition of perturbations into effects corresponding to different orders of center of mass displacement. A full analytical model for frequency tuning and shaking force balancing of the 2-DOF oscillator is derived using a pseudo-rigid-body model and assuming that it can be decomposed into two independent 1-DOF oscillators. The results are validated by the finite element method and show that practical mechanical watch specifications can theoretically be reached. A physical prototype was also constructed and preliminary experimental results confirm the theory as well as the simulations. |
| Databáze: | OpenAIRE |
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