Differential Chronograph Coupling for Stable Mechanical Watch Rate

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Solution Overview

Problem

Existing mechanical horological movements with chronograph mechanisms experience variations in movement rate and amplitude due to differing energy consumption based on the activation state of the chronograph, leading to complications in isochronism and complexity in the regulating member.

Innovation Solution

A horological movement with a differential coupling mechanism that instantaneously couples the chronograph train to the regulating member using a secondary energy source, allowing for low motive energy consumption and precise regulation, featuring a first input wheel driven by the running train, an output wheel meshed with the chronograph train, and a drive assembly with balls and a spring washer for non-slip rolling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a complex coupling mechanism (wolf-tooth, star-wheels, oblong slots) is used to couple the chronograph train to the regulating member, then the chronograph can be activated, but the device complexity increases and the escape wheel becomes more complex

Engineering Contradiction:

Improvechronograph activation capabilityVSAvoidcoupling mechanism complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The coupling mechanism is divided into separate functional components: a cam member with cam surfaces, a lever with actuating surfaces, and a locking member. This segmentation allows each component to perform a specific function independently, reducing overall complexity while maintaining chronograph activation capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention introduces an intermediate coupling mechanism between the chronograph control device and the chronograph train. This intermediary system uses a cam-lever-locking member assembly to transmit motion, simplifying the connection while enabling smooth engagement and disengagement of the chronograph function.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Stability of the object's composition

If the chronograph train is separated from the primary energy source and dedicated to the running train, then the power reserve stability improves, but the energy consumption varies between chronograph activation states causing rate variations

Engineering Contradiction:

Improvepower reserve stabilityVSAvoidmovement rate consistency

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The coupling mechanism dynamically engages and disengages the chronograph train from the regulating member based on activation state. The cam profiles are designed to provide smooth transitions between engaged and disengaged states, ensuring that energy consumption variations do not cause abrupt rate changes or affect the stability of the primary power reserve.

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If a traditional coupling mechanism is used, then the chronograph can be coupled to the regulating member, but the motive energy consumption increases and the coupling is not instantaneous

Engineering Contradiction:

Improvechronograph coupling capabilityVSAvoidmotive energy consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The cam-based coupling mechanism enables rapid engagement and disengagement of the chronograph train by skipping through the intermediate positions. The cam profiles are designed to achieve quick transition from disengaged to engaged state, minimizing the time and energy required for coupling while maintaining reliable connection.

Inventive Principle:

Principle #21Skipping (Rushing through)

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 differential coupling ensures consistent energy supply to the chronograph mechanism, maintaining isochronism and reducing complexity, enabling quick and precise operation of chronograph functions without the need for a secondary regulating member.

Implementation Method 1

a drive assembly with balls and a spring washer for non-slip rolling

Methodology Applied

Scientific EffectRolling friction: Friction

Implementation Method 2

a drive assembly with balls and a spring washer for non-slip rolling

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS12411457B2Horological movement comprising a chronograph mechanism

Publication Date: 2025.09.09 BLANCPAIN SA

AI summary

A horological movement including a running train driven by a first energy source; a regulating member for regulating the running train; a chronograph mechanism including a chronograph train driven by a second energy source; a coupling configured to couple the chronograph train, on demand, to the regulating member to regulate the chronograph train using the regulating member; a chronograph start/stop control device cooperating with the coupling; wherein the coupling is a differential coupling including a first input wheel driven by the running train and having a rotational speed that is regulated by the regulating member; an output wheel meshed with the chronograph train; a second idle input wheel cooperating directly or indirectly with the chronograph start/stop control device; the coupling including a drive assembly configured to rotate the output wheel at the rotational speed regulated by the regulating member.