Elastic Washer Micro-Adjustment for Timepiece Balance Precision

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing methods for adjusting the balance and inertia of clockwork balance wheels in timepieces are limited in precision, typically allowing adjustments of a few tens of seconds per day, which is not fine enough for precise rate regulation due to the fineness of the adjustment required.

Innovation Solution

The introduction of lightweight, annular elastic washers that can be easily attached to a relief rod or a smooth rod, allowing for micro-adjustments by providing a pinching torque and enabling adjustments of the order of a few tenths of a second per day, significantly improving the precision of rate adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional weights, screws, or nuts are used for balance adjustment, then the adjustment mechanism is simple and robust, but the adjustment precision is limited to a few tens of seconds per day

Engineering Contradiction:
Improverate adjustment precisionVSAvoidadjustment mechanism complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The balance adjustment system is segmented into multiple independent components: the balance wheel, hairspring, and multiple adjustable weights. Each weight can be independently positioned on the balance wheel periphery, allowing fine-grained control of the moment of inertia. This segmentation enables precise adjustment of the balance rate by making small, incremental changes to the weight distribution rather than relying on a single coarse adjustment mechanism.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The adjustment mechanism transitions from one-dimensional linear adjustment (screw rotation) to two-dimensional radial positioning. Weights can be positioned at different radial distances from the balance wheel center and at different angular positions around the periphery. This dimensional change provides a much larger adjustment range and finer control over the moment of inertia, enabling precision adjustments of a few seconds per day or better.

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

2Measurement precision

If screw/nut assemblies are used for inertia adjustment, then the structure is simple, but the fineness of adjustment is insufficient (only a few seconds per day at best)

Engineering Contradiction:
Improveinertia adjustment finenessVSAvoidadjustment operation difficulty
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The adjustment system is made dynamic and reversible. Weights can be easily added, removed, or repositioned on the balance wheel periphery without permanent modification. This dynamic capability allows the timekeeper to make continuous adjustments to optimize performance under varying conditions (temperature, humidity, position) and to reverse adjustments if needed, providing flexibility that static screw/nut assemblies cannot match.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the physical parameters of the balance assembly by varying the moment of inertia through weight positioning. By adjusting the radial distance and angular position of weights, the moment of inertia can be precisely controlled. This parameter change approach provides continuous adjustment capability across a wide range, enabling fine-tuning of the balance rate with precision of a few seconds per day or better.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If material is added by inkjet printer or ablated by laser, then adjustment precision can be improved, but the manufacturing complexity and cost increase significantly

Engineering Contradiction:
Improverate adjustment precisionVSAvoidmanufacturing simplicity
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

Instead of directly modifying the balance wheel structure through complex manufacturing processes (inkjet printing, laser ablation), the invention uses discrete weight components that are copied and positioned on the balance wheel periphery. These weights are simple, standardized parts that can be manufactured using conventional processes and then assembled in different positions to achieve the desired moment of inertia. This copying approach achieves precision adjustment without the manufacturing complexity of direct material deposition or removal.

Inventive Principle:
Principle #26Copying

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

These washers enable precise and fine adjustments of the balance wheel's rate, offering a more sensitive adjustment system than traditional screws, allowing for adjustments as precise as a tenth of a second per day, while maintaining minimal influence on the inertia and rate variation.

Implementation Method 1

skirt (11) arranged to allow an introduction or an extraction of this washer (1) with respect to a corresponding relief rod (3) under the action of a radial and/or axial force

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

The balance and inertia settings of a clockwork balance determine the frequency of oscillation and the regularity of the rate

Methodology Applied
Scientific EffectOscillation: Harmonic Oscillator

Data Source

PatentEP3144742B1Inertia micro-adjustment of a timepiece balance
Publication Date: 2018.10.31 ETA SA MFG HORLOGERE SUISSE
  • EP3144742B1 patent drawingFigure 1~5
  • EP3144742B1 patent drawingFigure 6~11
  • EP3144742B1 patent drawingFigure 8~19

AI summary

A balancing washer (1), arranged for retention on a rod (3, 30), with relief (3) or smooth (30), which comprises a balance wheel (2) or a weight (4) attached to a balance wheel (2). This washer (1) is a substantially annular elastic washer around an orifice (10) arranged to at least partially surround said rod (3, 30), and comprises at least one elastic skirt (11) arranged to allow insertion or extraction of said washer (1) relative to said rod (3, 30) under the action of a radial and/or axial force, and to ensure clipped retention on said rod (3, 30) in the absence of force on said washer (1), and said washer (1) comprises a gripping and/or angular indexing means (6) on a peripheral edge (7) comprising this washer (1).