Chronograph Gear Train Driven by Independent Mainspring

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Solution Overview

Problem

The existing chronograph mechanisms in wristwatches suffer from energy tapping from the going train to the chronograph gear train, limiting the smallest measurable time interval to around 0.16s or 0.2s due to the frequency of the balance wheel oscillations, making precise time measurement challenging, especially on smaller dial diameters.

Innovation Solution

The chronograph gear train is directly driven by a mainspring, with an escapement wheel regulating its rotational speed, eliminating energy transfer from the going train and allowing for a mobile to rotate once per second, enabling measurement of hundredths of a second.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the chronograph gear train is driven from the finishing train, then the chronograph mechanism can be powered, but energy is subtracted from the escapement and balance wheel, affecting timepiece precision

Engineering Contradiction:
Improvepower to chronograph gear trainVSAvoidoscillation frequency precision
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The patent divides the power source into two independent systems: the mainspring powers both the finishing train (via the escape wheel) and the chronograph gear train (via the chronograph escape wheel). This segmentation eliminates energy theft from the balance wheel while maintaining power supply to both subsystems.

Inventive Principle:
Principle #1Segmentation

2Productivity

If the chronograph gear train is driven from the finishing train, then the chronograph can operate, but the smallest measurable time interval is limited to 0.16s or 0.2s due to balance wheel oscillation frequency

Engineering Contradiction:
Improvemeasurement rangeVSAvoidsmallest measurable time interval
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

Instead of deriving chronograph power from the finishing train (which limits speed to balance wheel oscillation frequency), the patent inverts the relationship by giving the chronograph its own direct power source from the mainspring, enabling independent high-speed operation.

Inventive Principle:
Principle #13The other way round (Inversion)

3Reliability

If the chronograph gear train is given more teeth with triangular shape and light braking spring, then gear flutter is prevented, but the mechanism becomes more complex

Engineering Contradiction:
Improvegear train stabilityVSAvoidchronograph gear train structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the braking function from the chronograph gear train by implementing it in the chronograph escape wheel mechanism instead. This removes the need for separate braking springs and complex gear train modifications while maintaining stability.

Inventive Principle:
Principle #2Taking out (Extraction)

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 significantly increases the measurement range, allowing for precise measurement of hundredths of a second without energy interference from the going train, enhancing the chronograph's functionality.

Implementation Method 1

a first mainspring (1, 6) capable of storing and releasing energy in a cyclic manner

Methodology Applied
Scientific EffectElastic potential energy storage and release: Spring

Implementation Method 2

a chronograph escape wheel (2) capable of converting the continuous rotation of a chronograph pinion (4a) into periodic impulses

Methodology Applied
Scientific EffectMechanical escapement: Escapement

Data Source

PatentEP1978424B1Chronograph
Publication Date: 2011.11.02 MONTRES JOURNE
  • EP1978424B1 patent drawingFigure 1~1.1
  • EP1978424B1 patent drawingFigure 2~2.1
  • EP1978424B1 patent drawingFigure 3~3.1

AI summary

The chronograph has a kinematic chain provided between a mainspring and an exhaust associated with a regulator. A chronograph wheel (4) includes a mobile wheel (4a) with an end connected with the kinematic chain by an intermediate of an engaging mechanism and another end directly connected with the mainspring. A connection between another mobile wheel (4f) of the chronograph wheel and the kinematic chain comprises an escape wheel (2) of the chronograph integrated with a mobile of the kinematic chain. An engaging mechanism is associated with a brake unit.