Watch Escapement Bistable Spring Torque Compensation
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Solution Overview
Problem
The existing bistable spring escapement mechanism proposed in WO 2018/002773 is functionally defective, as it can only operate effectively when the winding rocker and winding mobile pivot in the same direction, leading to either mechanical blockage or energy loss due to uneven lever arms, resulting in poor efficiency and reliability.
Innovation Solution
The introduction of a monostable elastic member that compensates for variations in the winding torque applied to the winding rocker, ensuring balanced operation in both directions of rotation by adapting the restoring force to match the dimensions and characteristics of the other escapement mechanism components, thereby preventing jamming and energy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the winding lever and winding wheel pivot in the same direction (clockwise) to wind the bistable blade, then the lever arm is sufficient to overcome the restoring force of the bistable spring, but when winding in the opposite direction (counterclockwise), the small lever arm is insufficient to overcome the restoring force, causing the mechanism to lock and the escapement to fail
Solution Approach 1:
A monostable elastic element is introduced as an intermediary component between the winding lever and the frame. This element provides additional torque assistance during counterclockwise winding operations, enabling the winding lever to overcome the bistable spring's restoring force in both directions without causing excessive torque during clockwise winding
Solution Approach 2:
The system changes the elastic properties and configuration of the spring mechanism by combining a bistable spring with a monostable elastic element. The monostable element's physical characteristics (elastic modulus, geometry) are specifically designed to provide asymmetric torque compensation, softening the mechanical constraint during counterclockwise winding while maintaining sufficient leverage during clockwise winding
2Ease of operation
If the lever arm is designed to be long enough to overcome the restoring force during counterclockwise winding, then winding in both directions becomes possible, but the torque acting on the winding lever becomes too great during clockwise rotation, resulting in energy losses due to shocks and poor escapement efficiency
Solution Approach 1:
The monostable elastic element acts as a torque-regulating intermediary that selectively engages during clockwise winding to limit the maximum torque transmitted to the winding lever. This prevents excessive force during the locking phase, reducing shock-related energy losses while still enabling sufficient leverage for counterclockwise winding
Solution Approach 2:
The monostable elastic element预先 (in advance) stores elastic energy and provides cushioning effect before the locking phase occurs. By pre-loading the elastic element during the winding process, the system prepares for the upcoming locking event, reducing the impact shock and associated energy losses when the escapement mechanism locks
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
This solution ensures the winding rocker pivots alternately in a perfectly balanced manner, enhancing the efficiency and reliability of the escapement mechanism compared to similar mechanisms, by compensating for torque variations and maintaining balanced operation.
Implementation Method 1
a monostable elastic element (10c) compensating for a variation in the winding torque applied to the winding rocker (3) by the escape wheel(s) (4, 5) according to the direction of rotation
Implementation Method 2
an elastic blade with bistable behavior obtained by buckling said blade, initially straight, after bringing its two fixed ends together symmetrically with respect to a median pivot point corresponding to the inflection point of said elastic blade
Implementation Method 3
a bistable leaf spring L... capable of pivoting around said median point, forming the inflection point of the bistable leaf spring L... bringing said bistable elastic blade from a stable rest state to a metastable winding state
Data Source
Figure 1a~1c
Figure 2a~2c
Figure 3a~3c
AI summary
The present invention relates to a watch escapement mechanism (1) comprising a bistable elastic blade (L) working in buckling around a median inflection point between two anchor points (A, B), a winding rocker (3) of said bistable elastic blade (L), and an escapement mobile (4, 5) arranged to sequentially transmit a driving torque to the winding rocker (3) so as to rotate said winding rocker alternately in a clockwise and counterclockwise direction, and a release rocker (2) fixed to the bistable elastic blade (L) at its median inflection point and arranged to cooperate with a regulating member (0) oscillating of said watch movement at each alternation of the latter so as to transmit to it an impulse following a release of the elastic blade (L).Characteristically, the mechanism of the invention also includes a monostable elastic element (10c) for compensating a variation in the drive torque of the winding rocker (3) by the escapement mobile (4, 5) as a function of the direction of rotation of said winding rocker (3).