Deformable Barrel Ratchet for Watch Over-Winding Protection

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Solution Overview

Problem

Existing self-winding mechanical watches face issues with over-winding, leading to premature wear and degradation of the barrel due to increased friction and pressure, which conventional limiting systems cannot effectively address.

Innovation Solution

A deformable ratchet mechanism is introduced that disengages from the winding gear when excessive torque is applied, preventing over-winding and reducing friction-related wear by positioning the limiting device outside the cylinder.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a sliding-friction mechanism is used to limit winding of the barrel spring, then over-winding is prevented, but wear and performance deterioration occur due to friction between the spring blade and drum wall

Engineering Contradiction:
Improveprevention of over-windingVSAvoidservice life of barrel
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent extracts the winding limitation function from the barrel interior sliding-friction mechanism and relocates it to a ratchet mechanism positioned outside the barrel. The ratchet engages with the winding train to prevent reverse rotation, thereby separating the limitation function from the friction-causing sliding contact between spring and drum wall.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the sliding-friction mechanical limitation system with a ratchet-and-pawl mechanical system. Instead of relying on friction between the spring blade and drum wall to prevent over-winding, the ratchet mechanism uses positive engagement of teeth to block reverse rotation, eliminating the harmful friction while maintaining the over-winding protection function.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Power

If high torque is required to drive the mechanism, then the support forces and friction of the spring blade against the wall are accentuated, but this leads to wear and deterioration of the barrel

Engineering Contradiction:
Improvetorque transmissionVSAvoidwear of drum wall
Core Design Contradiction:
PowerVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the torque transmission function from the friction-based spring-blade system and implements it through a ratchet mechanism with direct tooth engagement. The ratchet receives torque from the winding train and transmits it to the barrel winding shaft without requiring friction between the spring and drum wall, thereby eliminating wear while maintaining power transmission.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces the ratchet mechanism as an intermediary between the winding train and the barrel winding shaft. This intermediary component enables torque transmission through positive mechanical engagement of teeth rather than through friction, eliminating the harmful wear of the drum wall while efficiently transmitting the required power.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If the ratchet is made deformable to disengage at high torque, then over-winding protection is achieved, but the structure becomes more complex

Engineering Contradiction:
Improveover-winding protectionVSAvoidratchet structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies dynamics by making the ratchet deformable rather than rigid. The ratchet is designed with elastic properties that allow it to flex and disengage from the winding train when excessive torque is detected, providing automatic over-winding protection. This dynamic characteristic enables the simple deformable structure to replace more complex mechanical limiters.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements self-service through the deformable ratchet's automatic disengagement mechanism. When torque exceeds the safe threshold, the ratchet naturally deforms and disengages from the winding train without requiring external control systems, sensors, or additional actuation mechanisms. The structure protects itself and the barrel through its inherent elastic properties.

Inventive Principle:
Principle #25Self-service

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 deformable ratchet mechanism effectively prevents over-winding, reducing wear and maintaining barrel performance by eliminating the need for internal friction-based limiting systems.

Implementation Method 1

the ratchet is deformable to be able to disengage the ratchet from the winding train. Thus, by deforming, the ratchet is no longer driven by the winding train

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

the peripheral rim is connected to the hub by at least one spring, preferably several connecting springs. The connecting spring(s) contract or stretch when the torque is substantially greater than the threshold value

Methodology Applied
Scientific EffectSpring: Spring

Data Source

PatentEP4375756B1Winding device, in particular for a timepiece barrel, provided with a disengageable ratchet
Publication Date: 2026.05.20 NIVAROX FAR SA
  • EP4375756B1 patent drawingFigure 1~2
  • EP4375756B1 patent drawingFigure 3~4

AI summary

The invention relates to a winding device (1), in particular for a mainspring barrel (2) equipped with a spring, comprising a ratchet (3) fixedly mounted on a rotating winding shaft, the rotating winding shaft being, for example, a winding shaft for the mainspring barrel (2), the rotation of which winds the mainspring barrel (2), and a winding gear train (4) meshing with the ratchet (3), the rotation of the winding gear train (4) causing the rotation of the ratchet (3) and that of the rotating winding shaft by applying a torque to the ratchet (3), characterized in that the ratchet is deformable so as to be able to disengage the ratchet (3) from the winding gear train (4). The invention also relates to a watch movement comprising such a winding device (1).