Magnetic Equalization Device for Watch Torque Stabilization

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Solution Overview

Problem

Existing watch movement equalization devices, such as the 'stackfreed', suffer from high friction leading to energy loss and component wear, and are sensitive to tolerances due to their mechanical nature, which complicates maintaining a constant driving torque as the mainspring winds and unwinds.

Innovation Solution

A magnetic equalization device using a first and second magnetic element, such as a bipolar permanent magnet and a cam, generates a variable auxiliary torque that opposes the variation in the driving torque, eliminating friction and potentially zero energy dissipation by leveraging conservative magnetic forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a mechanical equalization device like stackfreed is used, then the driving torque can be equalized, but friction causes energy loss and component wear

Engineering Contradiction:

Improvetorque equalizationVSAvoidenergy loss due to friction

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent replaces the mechanical stackfreed equalization device with a magnetic field-based system. A permanent magnet interacts with a ferromagnetic cam to produce the equalizing torque without mechanical contact between the equalization components, thereby eliminating friction-induced energy loss while maintaining torque equalization functionality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a magnetic field as an intermediary between the mainspring barrel and the equalization mechanism. The magnetic field transmits the equalizing torque through the ferromagnetic cam without requiring direct mechanical contact, reducing friction and energy loss while achieving the desired torque regulation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a mechanical equalization device like stackfreed is used, then the driving torque can be equalized, but intense friction leads to accelerated wear of components

Engineering Contradiction:

Improvetorque equalizationVSAvoidcomponent lifespan

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent substitutes the mechanical contact-based stackfreed mechanism with a magnetic field-based equalization system. The permanent magnet and ferromagnetic cam interact through magnetic attraction rather than mechanical friction, dramatically reducing wear on components and extending their operational lifespan while maintaining torque equalization.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If a mechanical equalization device is used, then torque equalization is achieved, but sensitivity to tolerances complicates manufacturing

Engineering Contradiction:

Improvetorque equalizationVSAvoidtolerance sensitivity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent utilizes the non-linear magnetic attraction force between the permanent magnet and ferromagnetic cam to achieve torque equalization. By carefully designing the cam profile and magnetic field distribution, the system compensates for manufacturing tolerances in a way that is less sensitive than mechanical contact systems, as magnetic fields can be more easily adjusted and optimized through material selection and geometric design.

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 magnetic equalization device provides a non-contact system that maintains a consistent driving torque without energy loss, reducing wear and improving the reliability of the watch movement by utilizing conservative magnetic forces to stabilize the torque across the mainspring's winding cycle.

Implementation Method 1

The equalization device according to the invention comprises a first magnetic element and a second magnetic element arranged to exert a variable magnetic force on each other depending on their relative position and, respectively, the degree of winding of the mainspring

Methodology Applied

Scientific EffectMagnetic force: Magnetism

Implementation Method 2

In a principal embodiment, at least one of said first and second magnetic elements comprises a permanent magnet. In an advantageous variant, these two magnetic elements are formed, respectively, by a bipolar permanent magnet and a cam made of a material with high magnetic permeability

Methodology Applied

Scientific EffectMagnetic force: Magnetism

Data Source

PatentEP3312681B1Clock movement comprising a device for equalising an engine torque

Publication Date: 2020.01.29 MONTRES BREGUET SA

Figure 1A~1B
Figure 2
Figure 3~5

AI summary

The watch movement comprises a mechanism and a barrel (111) arranged to drive the mechanism. The barrel includes a drum (131) and a mainspring to exert a driving torque that varies according to the degree of winding of the mainspring (133). The watch movement further includes an equalizing device (203, 207) kinematically connected to the barrel so as to be driven by it and to exert an auxiliary torque that also varies according to the degree of winding of the mainspring in order to counteract variations in the driving torque.The equalization device comprises a first magnetic element (203) and a second magnetic element (207) which are arranged so that, when the equalization device is driven by the barrel, they move relative to each other, exerting on each other a magnetic force which varies according to the relative position occupied by the first magnetic element and the second magnetic element and which produces the auxiliary torque.