Adjustable Inertia Balance Wheel for Watch Resonator

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Solution Overview

Problem

Existing watch resonator mechanisms face disruptions due to secondary oscillations around axes other than the primary XY plane, which can have frequencies that are multiples of the reference frequency, leading to precision issues if not carefully managed.

Innovation Solution

A balance wheel with adjustable inertia, featuring lateral weights that can be positioned to modify the balance's inertia, specifically to avoid secondary oscillations around axes like X and Y, ensuring these oscillations do not coincide with the reference frequency in the XY plane, thereby maintaining precision without affecting primary oscillations around the Z direction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the balance wheel uses a fixed inertia design, then the manufacturing is simpler, but the secondary oscillations cannot be controlled to avoid multiples of the reference frequency

Engineering Contradiction:
ImproveprecisionVSAvoidcomplexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The balance wheel employs adjustable lateral inertia weights that can be positioned at different locations along the balance arm. This dynamic adjustment capability allows the inertia distribution to be optimized for controlling secondary oscillations, resolving the contradiction between manufacturing simplicity and oscillation control precision.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes the inertia parameters of the balance wheel by repositioning the lateral weights. By adjusting the position of these weights, the moment of inertia about different axes can be modified to ensure secondary oscillation frequencies do not coincide with multiples of the reference frequency, thereby improving precision without requiring a completely complex design.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If lateral inertia adjustment weights are added to control secondary oscillations, then the precision is improved, but the device complexity increases

Engineering Contradiction:
ImproveprecisionVSAvoidcomplexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The balance wheel is segmented into functional components: the main balance structure and separate adjustable lateral inertia weights. This segmentation allows the weights to be independently positioned to control secondary oscillations without redesigning the entire balance wheel, thus improving precision while limiting the increase in overall complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The lateral inertia weights serve multiple functions: they adjust the moment of inertia about the X-axis to control secondary oscillations, and can potentially be positioned to influence other oscillation modes. This multi-functionality justifies the added complexity by providing comprehensive oscillation control from a single adjustable component system.

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

3Adaptability or versatility

If the lateral weights are positioned far from the main arm, then the inertia adjustment range is increased, but the balance structure becomes more complex

Engineering Contradiction:
Improveinertia adjustment rangeVSAvoidcomplexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The lateral weights are positioned in the lateral dimension (perpendicular to the balance arm's longitudinal axis) rather than extending the arm length. This dimensional approach allows for effective inertia adjustment about the X-axis without increasing the balance arm length or requiring complex extended structures, thus achieving adaptability while controlling complexity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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

The adjustable inertia balance wheel effectively controls and minimizes significant secondary oscillations, ensuring the resonator mechanism operates with enhanced precision by allowing the secondary oscillation frequency to differ from the reference frequency, thus improving the overall accuracy of the clock movement.

Implementation Method 1

the first lateral weight being mounted movably on the main arm of the balance to be able to take a plurality of positions more or less close to the main arm in order to adjust the inertia of the balance

Methodology Applied
Scientific EffectMoment of inertia: Moment of Inertia

Implementation Method 2

the inertial element being subjected to return forces exerted by a virtual pivot comprising first elastic blades each fixed to said inertial element and to said anchor block

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4425273A1Balance for timepiece resonator mechanism provided with lateral inertia adjustment weights
Publication Date: 2024.09.04 THE SWATCH GRP RES & DEVELONMENT LTD
  • EP4425273A1 patent drawingFigure 1~2
  • EP4425273A1 patent drawingFigure 3~4
  • EP4425273A1 patent drawing

AI summary

The invention relates to a balance wheel (15) for a resonator mechanism (1) in watchmaking, comprising a main arm (6) arranged along a longitudinal axis, the balance wheel (15) including at least one first lateral weight (11) for adjusting the inertia of the balance wheel, the first lateral weight (11) being movably mounted on the main arm (6) of the balance wheel (15) so as to be able to assume a plurality of positions more or less close to the main arm (6) in order to adjust the inertia of the balance wheel (15). The invention also relates to a method for fine-tuning said resonator mechanism.