Watch Barrel Variable Thickness Wall Design

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Solution Overview

Problem

Traditional watch barrel designs cannot increase the volume of the housing for the mainspring, limiting the power reserve of the watch movement, and alternative designs that attempt to do so introduce significant axial play and wear issues.

Innovation Solution

The barrel design features a drum and cover with walls that have a variable thickness increasing away from the peripheral end, allowing for a larger housing height without axial or radial guide surfaces outside the barrel, minimizing play and wear, and made from materials like brass for precise manufacturing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the wall thickness of the drum and cover is reduced to maximize housing volume, then the power reserve is improved, but the structural strength and rigidity deteriorate

Engineering Contradiction:
Improvehousing volumeVSAvoidwall strength
Core Design Contradiction:
Volume of moving objectVSStrength

Solution Approach 1:

The patent applies local quality by varying the wall thickness of the drum and cover according to the specific functional requirements at different locations. The walls have non-uniform thickness distribution, with thicker sections where structural strength is needed and thinner sections where space is required, thereby resolving the contradiction between maximizing housing volume and maintaining wall strength.

Inventive Principle:
Principle #3Local quality

2Manufacturing precision

If the wall thickness is reduced uniformly, then the manufacturing precision is improved, but the structural reliability deteriorates

Engineering Contradiction:
ImprovemachinabilityVSAvoidbarrel reliability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent implements local quality through non-uniform wall thickness design, where different sections of the drum and cover have different thicknesses optimized for their specific functions. This allows thin walls in non-critical areas for easy manufacturing while maintaining adequate thickness in critical areas for reliability, thus resolving the contradiction between manufacturing precision and structural reliability.

Inventive Principle:
Principle #3Local quality

3Volume of moving object

If alternative designs are used to increase housing volume, then the power reserve is improved, but axial play and wear increase

Engineering Contradiction:
Improvehousing volumeVSAvoidbarrel stability
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The patent applies parameter changes by modifying the wall thickness parameter of the drum and cover from uniform to non-uniform distribution. This parameter optimization allows the housing volume to be maximized while maintaining adequate structural support to minimize axial play and wear, thereby resolving the contradiction between increased power reserve and maintained barrel stability.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3974913A1Barrel for timepiece
Publication Date: 2022.03.30 ROLEX SA
  • EP3974913A1 patent drawingFigure 1
  • EP3974913A1 patent drawingFigure 2
  • EP3974913A1 patent drawing

AI summary

Barrel for a watch movement, comprising a barrel shaft (20) around which is arranged in a movably rotating manner an assembly comprising a drum (30) and a cover (40) delimiting a housing (50) for receiving a barrel spring (51), the drum (30) and the cover (40) each having a wall (31, 41) extending from a peripheral end (34, 44) of the barrel to a central end of the barrel at the level of the barrel shaft (20), characterized in that at least a part of at least one of said walls (31, 41) has a variable thickness which increases continuously with respect to the peripheral end of the barrel.