Clock Barrel Assembly Bung Diameter Reduction

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Solution Overview

Problem

Conventional clockwork movement barrel architectures face challenges in reducing the diameter of the barrel arbor and bung while ensuring disassembly and maintaining fatigue strength, which limits the power reserve and storage capacity.

Innovation Solution

A clockwork movement with a barrel assembly featuring a multiphase cobalt-nickel-chromium alloy mainspring and a bung with a reduced radius-to-thickness ratio, combined with swing-limiting shim washers and a novel bung design, allows for a smaller bung diameter, enabling increased energy storage and ease of assembly/disassembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the diameter of the barrel arbor and bung is reduced to increase power reserve, then the storage capacity increases, but the fatigue strength and structural integrity deteriorate

Engineering Contradiction:
Improvepower reserveVSAvoidfatigue strength
Core Design Contradiction:
Quantity of substanceVSStrength

Solution Approach 1:

The patent employs a multiphase alloy for the mainspring comprising cobalt, nickel, chromium, iron, tungsten, and molybdenum. This composite material structure provides both the flexibility needed for compact spring design and the fatigue resistance required for reliable operation, resolving the contradiction between reduced diameter and maintained strength.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent specifies precise compositional parameters for the alloy (44-46% cobalt, 20-22% nickel, 17-19% chromium, etc.) and geometric parameters (bung radius less than nine times spring thickness). By optimizing these parameters, the design achieves maximum power reserve while maintaining adequate fatigue strength.

Inventive Principle:
Principle #35Parameter changes

2Quantity of substance

If the bung diameter is reduced to increase energy storage space, then the storage capacity increases, but the ease of assembly and disassembly deteriorates

Engineering Contradiction:
Improveenergy storage capacityVSAvoidease of assembly
Core Design Contradiction:
Quantity of substanceVSEase of operation

Solution Approach 1:

The patent introduces swing-limiting means comprising independent shim washers that are guided by bearing surfaces on the bung. This segmentation allows the bung to be smaller while maintaining assembly functionality through the modular shim washer components that guide and limit movement independently of the bung size.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The shim washers act as intermediary elements between the bung and the plate/bridge assembly. These intermediaries facilitate assembly and disassembly by providing guided movement and swing limitation, allowing a smaller bung to be used without compromising ease of operation.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Quantity of substance

If the bung diameter is reduced to increase power reserve, then the storage capacity increases, but the reliability deteriorates

Engineering Contradiction:
Improvepower reserveVSAvoidstructural integrity
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The multiphase alloy composition provides enhanced reliability through its composite structure, which combines the ductility of cobalt and nickel with the strength and wear resistance of chromium and tungsten. This material composition ensures reliable operation even with the reduced bung dimensions.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

By carefully controlling the alloy composition parameters and the geometric parameter of bung radius relative to spring thickness (less than nine times), the patent optimizes the balance between compact size and structural reliability, ensuring the reduced-diameter design maintains adequate fatigue strength and operational reliability.

Inventive Principle:
Principle #35Parameter changes

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 solution enhances the power reserve and storage capacity of the clockwork movement by reducing the bung diameter while ensuring structural integrity and ease of maintenance, thereby improving the reliability and efficiency of the energy storage mechanism.

Implementation Method 1

a multiphase alloy based on cobalt-nickel-chromium, comprising 44-46% cobalt, 20-22% nickel, 17-19% chromium, 4-6% iron, 3-5% tungsten, 3-5% molybdenum, 0-2% titanium, 0 to 1% beryllium, and having a Young's modulus of between 200 and 240 GPa and a shear modulus of between 80 and 100 GPa

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

swing-limiting means comprising at least one shim washer independent of said bung and guided by a bearing surface that comprises said bung and interposed between on the one hand said plate or respectively said bridge, and on the other hand said lid or respectively said drum

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP2756359B1Clock barrel assembly with reduced core diameter
Publication Date: 2016.03.23 ETA SA MFG HORLOGERE SUISSE
  • EP2756359B1 patent drawingFigure 1~3
  • EP2756359B1 patent drawingFigure 4
  • EP2756359B1 patent drawingFigure 5

AI summary

The invention relates to a clock movement (100), comprising a plate (10) and a bridge (11) supporting a barrel (1) that comprises a barrel spring (2) between a drum (3) and a surface (5) for receiving a core (4), and a cover (7) attached to said drum (3). Said spring (2) is made from a multiphase cobalt/nickel/chrome alloy, the Young's modulus of which is between 200 and 240 GPa and the shear modulus of which is between 80 and 100 GPa, and the ratio of the width/thickness thereof is between 3 and 23, wherein the maximum radius of said steel or stainless-steel core (4) relative to the pivot axis thereof (D) is less than nine times the maximum thickness of said spring (2), and said movement (100) comprises a means for limiting play, which comprises a chock ring (70) which is separate from said core (4) and which is guided by a bearing (44) of the latter.