Timepiece Escapement with Constant Draw Angle
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Solution Overview
Problem
Traditional escapements in watchmaking experience energy inefficiency due to increasing draw force during the unlocking phase, which disrupts the oscillations of the regulating member and affects isochronism, and existing solutions either rely on additional retention means or complex geometries.
Innovation Solution
The escapement features a convex rest surface for the entry pallet with a constant or decreasing draw angle, eliminating the increase in draw force and torque during the unlocking phase, thereby maintaining anchor retention without additional retention means and simplifying the design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional planar rest surface is used for the entry pallet, then the anchor is retained in the rest position, but the draw force increases during the unlocking phase causing energy loss and disrupting oscillations
Solution Approach 1:
The rest surface of the entry pallet is designed as a convex curved surface instead of a planar surface. This curvature allows the draw angle to remain constant or decrease during the unlocking phase, preventing the increase in draw force that occurs with planar surfaces. The curved geometry maintains anchor retention while eliminating the energy loss associated with increasing draw force during unlocking.
2Loss of energy
If the rest surface is designed to eliminate draw force increase, then energy efficiency improves, but additional retention means or complex geometries are required
Solution Approach 1:
The convex curved rest surface is designed to automatically maintain the draw angle within optimal limits during the unlocking phase through its inherent geometry. The curvature of the surface works with the natural motion of the anchor to keep the draw force constant or decreasing, eliminating the need for additional retention means such as magnets or friction devices. The geometry itself provides the retention function while maintaining energy efficiency.
Data Source
AI summary
A timepiece escapement comprising: an escapement wheel pivotably mounted about a first axis of rotation and intended to be driven by a power source; a lever pivotably mounted about a second axis of rotation, said lever comprising an entry pallet and an exit pallet, each pallet comprising a rest face arranged to alternately and sequentially lock the escapement wheel, the lever being suitable for transmitting pulses received from the escapement wheel to a regulating member arranged to oscillate, and for releasing the escapement wheel periodically under the control of said regulating member, wherein the rest face of the entry pallet is arranged such that, when it locks a tooth of the escapement wheel, a draw force is generated by the interaction between the rest face and the tooth to apply a torque that tends to retain the lever in the rest position. According to the invention, the rest face is shaped in such a way that the draw angle (Υ) at the contact point (C) of said face with a tooth of the escapement wheel is constant or decreases along the release stroke of the entry pallet.