Polymer Pivot System for Watch Shock Absorption

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Solution Overview

Problem

Existing shock-absorbing bearings for timepieces face issues with complex assembly, high friction, and inaccurate positioning due to the use of separate springs and stone components, which lead to radial play and potential damage to the balance wheel during axial displacement.

Innovation Solution

A polymer-based pivot system that integrates suspension and pivot functions in a single piece, utilizing a polymer material with low friction properties and adjustable dimensions to maintain constant radial clearance independent of axial displacement, reducing the number of components and manufacturing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If separate springs and stone components are used for shock absorption, then shock absorption function is provided, but device complexity and assembly complexity increase

Engineering Contradiction:
Improveshock absorption functionVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the spring function and pivot function into a single polymeric pivot system. The polymeric body integrates both the suspension element (replacing the separate spring) and the pivot bearing surface (replacing the separate stone components), eliminating the need for multiple separate parts and simplifying assembly while maintaining shock absorption capability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The polymeric pivot system performs multiple functions simultaneously: it acts as both the suspension element (spring) and the pivot bearing surface (stone), providing shock absorption, friction reduction, and precise positioning all through a single component rather than requiring separate specialized parts for each function.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Strength

If metal-on-metal pivoting is used, then structural strength is maintained, but friction increases significantly

Engineering Contradiction:
Improvestructural strengthVSAvoidfriction
Core Design Contradiction:
StrengthVSObject-generated harmful factors

Solution Approach 1:

The patent changes the material parameter from metal to polymer, fundamentally altering the friction characteristics of the pivoting interface. The polymeric material provides self-lubricating properties that dramatically reduce friction compared to metal-on-metal contact, while the polymer's mechanical properties are selected to maintain sufficient structural strength for the application.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs polymeric composite materials that combine the benefits of low friction with adequate mechanical strength. The polymer material acts as a composite solution that replaces the metal-on-metal interface, providing both the required structural integrity and the friction reduction necessary for smooth pivoting operation.

Inventive Principle:
Principle #40Composite materials

3Force

If conical spring housing is used, then axial displacement is absorbed, but radial play increases with axial displacement

Engineering Contradiction:
Improveaxial displacement absorptionVSAvoidradial play
Core Design Contradiction:
ForceVSManufacturing precision

Solution Approach 1:

The patent changes the geometric parameter of the housing from conical to cylindrical. This cylindrical configuration eliminates the coupling between axial and radial movements that exists in conical designs. When the polymeric pivot moves axially within the cylindrical housing, it does not generate radial play, thereby maintaining precise radial positioning of the balance wheel axis regardless of axial displacement magnitude.

Inventive Principle:
Principle #35Parameter changes

4Reliability

If multiple separate components are used, then functional specialization is achieved, but manufacturing cost increases

Engineering Contradiction:
Improvefunctional specializationVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent combines multiple separately manufactured components (spring, pierced stone, counter-pivot stone) into a single polymeric pivot system that can be manufactured as one integrated piece through molding processes. This consolidation reduces the number of manufacturing operations, eliminates the need for precise assembly of multiple parts, and reduces overall manufacturing cost while preserving all necessary functions.

Inventive Principle:
Principle #5Merging (Combining)

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 polymer-based pivot system provides improved shock absorption with reduced friction, precise positioning, and cost-effectiveness by minimizing parts and assembly complexity, while maintaining consistent performance across varying watch inclinations.

Implementation Method 1

a pivot system which combines the suspension function and the pivot function in a single piece... made of a polymeric material... arranged to absorb, at least in part, the shocks undergone by the timepiece mobile

Methodology Applied
Scientific EffectShock absorption: Damping

Implementation Method 2

utilizing a polymer material with low friction properties... the polymer-based pivot system provides improved shock absorption with reduced friction

Methodology Applied
Scientific EffectFriction reduction: Lubrication

Data Source

PatentEP2791742B1Polymeric shockproof system for a timepiece
Publication Date: 2017.04.26 ETA SA MFG HORLOGERE SUISSE
  • EP2791742B1 patent drawingFigure 1~2
  • EP2791742B1 patent drawingFigure 3~4
  • EP2791742B1 patent drawingFigure 5~6

AI summary

The invention relates to a shock-absorbing bearing for a shaft (120) of a train of a timepiece. The shaft includes a pivot shank (121). The bearing comprises a mounting (102, 103) provided with a recess for receiving a pivot system (126, 126') into which the pivot shank is inserted. The pivot system (126) is adapted to at least partially absorb the shocks to which the train of the timepiece is subjected.