Tourbillon Balance Stop Mechanism Using Axial Friction Disc

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Solution Overview

Problem

Existing balance-stop mechanisms for tourbillon watches are hindered by the rotating cage's pillars, are complex to manufacture and assemble, and are not suitable for balance wheels with interrupted or sectorial rims, leading to issues with integration and fragility when using materials like silicon.

Innovation Solution

A coaxial stop disc with an outer periphery beyond the pillars, actuated by levers that move along the axis of the cage, allowing friction contact with the balance wheel to stop it, and featuring elastic means for return to a rest position, enabling easy integration and compatibility with various balance wheel designs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional elastic arm stop mechanism is used, then the balance wheel can be stopped, but the mechanism is hindered by the rotating cage's pillars and cannot be effectively implemented

Engineering Contradiction:
Improvebalance stopping functionVSAvoidcompatibility with tourbillon cage structure
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The invention transitions from a radial stopping approach (elastic arm extending outward) to an axial stopping approach (disc moving along the cage axis). The stop disc is positioned axially beyond the pillars rather than radially, allowing it to contact the balance wheel's periphery without being blocked by the pillars in any angular position of the tourbillon cage.

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

2Reliability

If a double elastic arm spring is used to stop the balance, then the stopping function is achieved, but the production is complicated and adjustment is difficult

Engineering Contradiction:
Improvebalance stopping functionVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The stop mechanism is divided into separate functional components: a stop disc that contacts the balance wheel, actuating elements that move the disc axially, and elastic means that provide the stopping force. This segmentation allows each component to be manufactured and adjusted independently, simplifying production and assembly compared to a single complex double elastic arm spring.

Inventive Principle:
Principle #1Segmentation

3Reliability

If a long double elastic arm spring is used, then the balance can be stopped, but the spring can easily deform under shock and block the balance inadvertently

Engineering Contradiction:
Improvebalance stopping functionVSAvoidresistance to deformation
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

By moving the stopping action from a radial direction (requiring long elastic arms) to an axial direction (using a disc moving along the cage axis), the mechanism uses a shorter, more rigid structure. The axial movement path is constrained by the cage structure itself, providing inherent support that prevents deformation under shock.

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

4Reliability

If levers mounted on the cage are used to stop the balance, then the balance can be blocked, but the device includes many parts making assembly complex and adds weight to the cage

Engineering Contradiction:
Improvebalance stopping functionVSAvoidnumber of parts
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention combines multiple functions into fewer components. The stop disc serves both as the stopping surface and as a structural element integrated with the cage. The actuating elements are simplified compared to traditional lever mechanisms, reducing the total number of parts required for the stopping function.

Inventive Principle:
Principle #5Merging (Combining)

5Reliability

If levers and pads are mounted on the periphery of the cage, then the balance can be stopped, but the additional weight disturbs the inertia of the cage and increases thickness

Engineering Contradiction:
Improvebalance stopping functionVSAvoidcage weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The stopping mechanism is repositioned from the radial periphery of the cage to the axial direction. The stop disc is positioned axially beyond the pillars, allowing it to contact the balance wheel without adding significant radial thickness or weight to the rotating cage assembly.

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

6Reliability

If a bent flexible blade is used under the balance, then the balance can be stopped, but the device occupies important space in the direction of the cage shaft

Engineering Contradiction:
Improvebalance stopping functionVSAvoidspace occupation
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The invention moves the stopping mechanism from a position under the balance (occupying axial space near the shaft) to a position where the stop disc is axially beyond the pillars. This allows the stopping action to occur in a different spatial zone, reducing interference with the cage shaft area.

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

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 allows for effective stopping of the balance wheel in any position and with various rim configurations, reducing complexity, weight, and size, while being suitable for fragile materials like silicon, and can be easily integrated into existing tourbillon movements.

Implementation Method 1

move the disc along the axis of the cage so as to cause the balance wheel to stop by friction between the disc and the pendulum

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

elastic means for returning the disk to a rest position

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2787400B1Clockwork with tourbillon and balance stop mechanism
Publication Date: 2016.08.03 CHOPARD TECH
  • EP2787400B1 patent drawingFigure 1
  • EP2787400B1 patent drawingFigure 2
  • EP2787400B1 patent drawingFigure 3

AI summary

The invention relates to a clockwork with a tourbillon mechanism and a balance stop mechanism. The tourbillon mechanism includes a cage (4) and a rocker (12) mounted in the cage (4). The cage (4) comprises a lower cage portion (6) and an upper cage portion (7) connected by pillars (8). The stop mechanism includes a stop member (18) which is in rigid fixing without rotating with respect to the cage (4) and is capable of coming into contact with the balance (12) for the stop and a device (27, 28, 38-40 ) for actuating the stop element (18). The stop member (18) is in the form of a disk coaxial to the cage (4) through which the pillars (8) and having an outer periphery located radially beyond the pillars (8). The actuating device (27, 28, 38-40) comprises at least one actuating element adapted to cooperate with the outer periphery (20a) for moving the disc along the axis of the cage (4) so as to cause the stopping of the rocker (12) by friction between the disc and the rocker (12).