Horological Detent Escapement Self-Starting Mechanism
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Solution Overview
Problem
Detent escapements, particularly of the Robin type, face challenges with self-starting after inadvertent stoppages and are not adequately secured against shocks, making them unsuitable for use in wristwatches without additional complex geometries that increase friction and mass.
Innovation Solution
Incorporating an indirect impulse pallet-stone that remains out of contact with the escapement wheel during normal operation but comes into contact to provide an indirect impulse for self-starting after inadvertent movements or stoppages, ensuring reliable operation and reducing the risk of collisions within the locking device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a detent escapement is used to achieve direct impulse transmission, then efficiency and precision are improved, but self-starting capability after stoppage deteriorates
Solution Approach 1:
An intermediary component (indirect impulse pallet-stone) is introduced that remains out of contact during normal operation but activates during stoppage conditions. This pallet-stone serves as a mediator that transfers impulse from the escapement wheel to the balance when the direct impulse path is inactive, enabling self-starting without compromising normal efficiency.
Solution Approach 2:
The indirect impulse pallet-stone is pre-positioned and geometrically arranged to automatically engage when the balance stops or slows down. The geometry ensures that during normal operation the pallet-stone remains disengaged, but when the balance comes to rest, the escapement wheel automatically makes contact with the pallet-stone to provide the preliminary action needed to restart oscillation.
2Reliability
If additional geometries are added to secure against shocks, then reliability is improved, but device complexity and friction increase
Solution Approach 1:
The indirect impulse pallet-stone performs multiple functions: it enables self-starting after stoppage, provides shock security, and relaxes manufacturing tolerances. By combining these functions into a single geometric arrangement rather than adding separate components, the solution improves reliability without proportionally increasing complexity.
Solution Approach 2:
The invention changes the geometric parameters of the pallet-stone and its relationship to the escapement wheel and balance. By optimizing angles, positions, and dimensions, the design achieves shock security and self-starting capability while maintaining manufacturability and minimizing friction through proper clearances and contact surfaces.
3Reliability
If additional geometries are added to secure against shocks, then reliability is improved, but manufacturing precision requirements worsen
Solution Approach 1:
The geometric design incorporates built-in clearance and tolerance compensation that cushions against manufacturing variations. The indirect impulse mechanism is designed with geometric relationships that maintain functionality even when tolerances vary, as the mechanism relies on the absence of contact during normal operation rather than precise continuous engagement.
Data Source
AI summary
A horological detent escapement for a horological movement arranged to transmit a torque from said horological movement to an oscillating regulating organ of said horological movement, the regulating organ comprising a first mobile body and the escapement comprising a second mobile body and an escapement wheel. Said escapement wheel being arranged so as to transmit, during a half-phase of each oscillation of the regulating organ, a torque to said regulating organ via a direct impulse. The second mobile body comprises an indirect impulse means arranged so as to be in contact with the escapement wheel during normal operation and be out of contact during the other half-phase of each oscillation of the regulating organ when the escapement wheel does not transmit torque to the regulating organ, so as to transmit torque to said regulating organ via an indirect impulse, following an inadvertent movement or inadvertent stoppage of the horological movement.