Timepiece Oscillator Virtual Pivot Flexible Blades

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Solution Overview

Problem

Existing mechanical watch oscillators with pivotless designs face limitations in oscillation amplitude and guidance, leading to suboptimal isochronism and reduced power reserve due to friction and micro-movements affecting the geometric axis of oscillation.

Innovation Solution

A rotary oscillator with a virtual pivot, featuring a support element, flexible blades connecting the support to a balance wheel, and a rim for inertia, which allows for clean rotation and a restoring torque proportional to angular deflection, enhancing the power reserve and reducing damping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a pivotless oscillator design is used, then friction is reduced and power reserve is improved, but oscillation amplitude is limited and guidance is suboptimal

Engineering Contradiction:
Improvefriction lossVSAvoidoscillation amplitude range
Core Design Contradiction:
Loss of energyVSAdaptability or versatility

Solution Approach 1:

The balance wheel is segmented into multiple sectors with individual flexible blades connecting each sector to the support element. This segmentation allows each blade to independently guide its sector's motion, providing optimal guidance throughout the entire oscillation range while maintaining the pivotless friction-reduction benefit

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The flexible blades extend in multiple dimensions from the support element to connect with different sectors of the balance wheel. This multi-dimensional arrangement enables the blades to provide guidance forces in both radial and tangential directions, allowing for larger oscillation amplitudes while maintaining stable geometric axis guidance

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Ease of operation

If flexible blades are used to connect support element to balance wheel, then oscillation guidance is provided, but micro-movements occur affecting the geometric axis of oscillation

Engineering Contradiction:
Improveoscillation guidanceVSAvoidgeometric axis stability
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

Multiple flexible blades are merged into a unified structure where they collectively support the balance wheel sectors. The blades are arranged symmetrically and work in unison to maintain the geometric axis of oscillation, with each blade compensating for potential micro-movements of the others, thereby stabilizing the overall oscillation axis

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

Each flexible blade is designed with specific local properties including optimized thickness, length, and material composition to provide appropriate stiffness and flexibility. The blades have enhanced rigidity near the support element connection to minimize micro-movements while maintaining flexibility in the oscillation direction, creating localized quality variations that stabilize the geometric axis

Inventive Principle:
Principle #3Local quality

3Strength

If traditional pivot-based oscillators are used, then structural support is provided, but friction increases and power reserve decreases

Engineering Contradiction:
Improvestructural supportVSAvoidfriction loss
Core Design Contradiction:
StrengthVSLoss of energy

Solution Approach 1:

The traditional mechanical pivot-based support system is replaced with a flexible blade mechanism that provides structural support through elastic deformation rather than rigid contact. The flexible blades bend and flex to support the balance wheel, eliminating the need for physical pivots and their associated friction losses while maintaining adequate structural support

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

Solution Approach 2:

The flexible blades are designed as thin, elastic structures that replace rigid pivot connections. These blade-like elements flex under load to provide the necessary structural support and torque transmission without creating friction points, effectively substituting rigid mechanical connections with flexible elastic elements

Inventive Principle:
Principle #30Flexible shells and thin films

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 achieves higher quality factors and increased power reserve by ensuring fixed, frictionless oscillation with a virtual pivot, offering improved performance compared to prior art oscillators.

Implementation Method 1

flexible blades connecting the support element to the balance wheel capable of exerting a restoring torque on the balance wheel

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

producing a restoring torque almost proportional to the angular deflection

Methodology Applied
Scientific EffectHooke's Law: Hooke's Law

Implementation Method 3

a rim 4 mounted integral with the balance wheel 3 to give sufficient inertia to the oscillator 1

Methodology Applied
Scientific EffectInertia: Inertia

Data Source

PatentEP2911012B1Timepiece oscillator
Publication Date: 2020.07.22 CSEM CENTRE SUISSE D ELECTRONIQUE ET DE MICROTECHNIQUE SA
  • EP2911012B1 patent drawingFigure 1
  • EP2911012B1 patent drawingFigure 2
  • EP2911012B1 patent drawingFigure 3

AI summary

The invention relates to a rotary oscillator (1) for a timepiece comprising a support element (2) for mounting the oscillator (1) onto a timepiece, a balance wheel (3), a plurality of flexible blades connecting the support element (2) to the balance wheel (3) and capable of exerting a restoring torque on the balance wheel (3), and a rim (4) mounted integrally with the balance wheel (3). The plurality of flexible blades comprises at least two flexible blades, a first blade (51) arranged in a first plane perpendicular to the plane of the oscillator (1), and a second blade (52) arranged in a second plane perpendicular to the plane of the oscillator (1) and intersecting the first plane. The geometric axis of oscillation (7) of the oscillator (1) is defined by the intersection of the first plane and the second plane, said geometric axis of oscillation (7) crossing the first (51) and second (52) blades at 7/8ths of their respective length.