Bistable Flexible Anchor for Constant Force Escapement

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Solution Overview

Problem

The regularity of the escapement mechanism in timepieces is affected by irregular impulse intensity due to varying barrel torque, necessitating improved control over oscillations and impulse management.

Innovation Solution

A timepiece escapement mechanism featuring a flexible anchor with a bistable element, comprising an anchor head and fork connected by a prestressed bistable blade, which regulates energy transfer between the escape wheel and balance wheel, ensuring consistent impulse intensity and reduced inertial movements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional anchor with rigid connections is used, then structural strength is maintained, but impulse intensity varies irregularly due to barrel torque variations

Engineering Contradiction:
Improveregularity of escapementVSAvoidimpulse intensity consistency
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The patent applies parameter changes by transforming the rigid connection between anchor head and fork into a flexible connection using a bistable blade. This blade can change its stiffness parameter dynamically - remaining flexible during normal operation to allow regular oscillations, and becoming rigid during impulse transmission to ensure consistent force delivery to the balance wheel, thereby resolving the contradiction between structural strength and impulse consistency

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The bistable blade introduces dynamic behavior to the anchor structure. It can switch between two stable states, allowing the connection between anchor head and fork to adapt its mechanical properties during the escapement cycle. This dynamic characteristic enables the system to maintain regularity while delivering consistent impulse, as the blade's state changes synchronize with the escapement rhythm

Inventive Principle:
Principle #15Dynamics

2Reliability

If multiple components are used in the anchor to ensure strength and stability, then reliability is improved, but device complexity increases

Engineering Contradiction:
Improveoperational safetyVSAvoidnumber of anchor components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple traditional anchor components into a single integrated structure. The anchor head, fork, and bistable blade are combined into one piece, eliminating the need for separate pivots, joints, and connection elements. This merging maintains operational safety through the bistable mechanism while significantly reducing the number of parts and assembly complexity

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The bistable blade performs multiple functions simultaneously: it acts as both the connection element between anchor head and fork, and as the impulse transmission mechanism. This multi-functionality reduces the need for separate components while ensuring both structural integrity and consistent impulse delivery, thereby improving reliability without increasing complexity

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 achieves maximum regularity and high operational safety with reduced components, providing a constant force mechanism that decouples energy transmission, ensuring consistent impulse delivery to the balance wheel.

Implementation Method 1

a flexible blade (10) mounted prestressed in buckling between the head (2) at a first end (101) and the fork (6) at a second end (102)

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

this anchor (1) constituting a bistable system comprising at least two stable states and two metastable states

Methodology Applied
Scientific EffectBistability: Metastability

Data Source

PatentEP2893403B1Constant force flexible anchor
Publication Date: 2019.08.28 NIVAROX FAR SA
  • EP2893403B1 patent drawingFigure 1
  • EP2893403B1 patent drawingFigure 2~3
  • EP2893403B1 patent drawingFigure 4~5

AI summary

The assembly (1) has an anchor head (2) that is designed to collaborate with an escapement wheel (20) and a fork (6) that is designed to collaborate with a balance spring (30). An angular position of the fork with respect to the head is variable. A fixing blade (10) provides only permanent mechanical connection between the head and the fork. The head comprises an arm with a bearing and stop surface, and another bearing and stop surface that comprises another arm having the fork. Independent claims are also included for the following: (1) an escapement mechanism (2) a clock element.