Linear Elastic Drive Member for Constant Force Watch Motors

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Solution Overview

Problem

Traditional clockwork motors in watchmaking, such as those using spiral springs, suffer from inefficiencies due to friction, complex manufacturing processes, and non-constant force delivery, affecting the isochronism of watch mechanisms.

Innovation Solution

A clockwork motor with a support, elastic member, and drive element that utilizes a rectilinear translation of a drive element to deliver energy, eliminating the need for turns and incorporating elastic blades working in buckling and flexion to provide a substantially constant force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a traditional spiral spring barrel is used as the driving force, then the timepiece can be powered, but energy losses of approximately 15% occur due to friction between spring coils and the barrel drum

Engineering Contradiction:
Improveenergy lossVSAvoidfriction between spring coils and barrel drum
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the spiral spring component entirely, replacing it with a linear elastic element that operates without coils. This removes the source of friction between spring coils and the barrel drum, reducing energy losses from 15% to approximately 0-1% as stated in the patent.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the traditional spiral spring mechanical system with a linear elastic element that stores and releases energy through elastic deformation rather than coil unwinding. This substitution eliminates the frictional mechanical interaction between spring coils and the barrel drum.

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

2Ease of manufacture

If a spiral spring is shaped from inverted S-form to spiral form, then the spring can be manufactured, but the manufacturing process must carefully consider the elastic limit of the material and requires extensive watchmaking experience

Engineering Contradiction:
Improvespring manufacturingVSAvoidelastic limit consideration
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The invention removes the complex spiral spring shaping process entirely, replacing it with a linear elastic element that can be manufactured using simpler processes. This eliminates the need to carefully control the elastic limit during complex coil formation while maintaining the necessary elastic functionality.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of shaping a linear element into a spiral form (traditional approach), the invention inverts the approach by using a linear elastic element that remains linear throughout its operation. This inversion simplifies the manufacturing process from complex spiral forming to simpler linear component fabrication.

Inventive Principle:
Principle #13The other way round (Inversion)

3Stability of the object's composition

If an intermediate spiral spring is introduced between the driving element and the escapement, then the torque can be made more constant, but the movement is complicated by introducing an additional component

Engineering Contradiction:
ImproveisochronismVSAvoidnumber of components
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the need for an intermediate spiral spring by using a linear elastic element that inherently delivers more constant torque. This removes the additional component while maintaining or improving the isochronism of the movement.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the fundamental parameter of the elastic element from spiral geometry to linear geometry, which alters the torque delivery characteristics. The linear elastic element provides a more constant force output throughout its stroke, improving isochronism without requiring additional intermediate springs.

Inventive Principle:
Principle #35Parameter changes

4Ease of manufacture

If a spiral spring barrel is used, then the driving element can be assembled, but the assembly requires numerous handling steps and relies on extensive watchmaking experience

Engineering Contradiction:
Improveassembly processVSAvoidhandling steps
Core Design Contradiction:
Ease of manufactureVSEase of operation

Solution Approach 1:

The invention removes the spiral spring assembly process entirely, replacing it with a linear elastic element that requires fewer handling steps. This simplifies the assembly process while reducing the dependency on extensive watchmaking experience for proper installation.

Inventive Principle:
Principle #2Taking out (Extraction)

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

This design significantly reduces energy loss to less than 1%, improves isochronism by delivering a constant force, and simplifies manufacturing by eliminating the need for intermediate springs and complex assembly processes.

Implementation Method 1

an elastic element (6) connecting said drive element (5) to said support (7)... said elastic element comprising at least one elastic blade (6a, 6b, 6c)

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

said elastic element comprising at least one elastic blade (6a, 6b, 6c) working in buckling and/or flexion

Methodology Applied
Scientific EffectBuckling:

Implementation Method 3

said elastic element comprising at least one elastic blade (6a, 6b, 6c) working in buckling and/or flexion

Methodology Applied
Scientific EffectFlexion:

Data Source

PatentEP3707563B1Timepiece drive member
Publication Date: 2022.11.16 PATEK PHILIPPE SA
  • EP3707563B1 patent drawingFigure 1~2
  • EP3707563B1 patent drawingFigure 3a~3b
  • EP3707563B1 patent drawingFigure 4~5

AI summary

The invention relates to a driving member (1) of a timepiece, comprising a support element (7), an elastic member (6) and a drive element (5), characterised in that said drive element (5) can be moved and guided translationally with respect to the support element (7) by means of said elastic member (6), wherein this translation allows a force to be transmitted to a timepiece mechanism (2, 3). The invention also relates to a timepiece mechanism comprising a driving member of this type, a timepiece such as a wrist watch comprising a timepiece mechanism of this type, and the use of such a driving member as a source of power for a timepiece mechanism that is independent of the finishing gear train.