Watch Spring Pivoting Blade Prevents Unintentional Triggering

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Solution Overview

Problem

Existing watch springs used in watch mechanisms often result in unintentional triggering due to insufficient force threshold, and increasing the preloading force or adding additional springs either provide minimal gain or are not feasible in all configurations, leading to difficulties in operating the pusher effectively.

Innovation Solution

A watch spring design with a pivoting blade that compresses between the heel and support element during movement between minimum and maximum angular positions, increasing the force threshold without significantly increasing the force required to operate the pusher, and allowing for easy integration into existing constructions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the preloading force of the coil spring is increased to prevent unintentional triggering, then the force threshold is improved, but the maximum force to be exerted on the pusher at the end of its travel increases significantly

Engineering Contradiction:
Improveforce thresholdVSAvoidmaximum force at end of travel
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The patent changes the geometric parameters of the elastic blade, specifically introducing a curvature radius R at the second end of the blade. This geometric modification allows the blade to pivot on the support element, fundamentally changing how force is applied and distributed throughout the functional member's range of motion, thereby resolving the contradiction between threshold force and maximum force.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces a dynamic pivoting mechanism where the second end of the elastic blade pivots on the support element during the functional member's rotation. This dynamic element allows the spring to adapt its force application throughout the motion range, providing high threshold force when needed while reducing maximum force requirements, thus resolving the contradiction.

Inventive Principle:
Principle #15Dynamics

2Reliability

If the size of the spring is resized to increase the pre-winding threshold, then the force threshold is improved, but the gain is minimal and the solution is not always feasible depending on the configuration

Engineering Contradiction:
Improvepre-winding thresholdVSAvoidconfiguration feasibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

Instead of resizing the entire spring, the patent modifies specific geometric parameters - introducing a curvature radius R at the blade's second end and establishing a specific relationship between R, the blade length L, and the functional member's radius r. This targeted parameter change achieves the desired threshold increase while maintaining adaptability to various configurations.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent segments the spring into distinct functional zones: the heel portion secured to the frame, the elastic blade portion, and the second end with curvature radius R that pivots on the support element. This segmentation allows each portion to be optimized independently, achieving high threshold force while maintaining configuration feasibility.

Inventive Principle:
Principle #1Segmentation

3Reliability

If a second spring is added to the pusher to increase the force threshold, then the reliability is improved, but the device complexity increases and the solution is not always feasible

Engineering Contradiction:
Improveforce thresholdVSAvoidspring configuration
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent makes the single elastic blade perform multiple functions: it provides the return force for the functional member, establishes the force threshold through its pivoting action, and replaces the need for a separate coil spring in the pusher. This multi-functionality resolves the contradiction by achieving reliability improvement without increasing device complexity.

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

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 effectively prevents untimely triggering of the functional member while maintaining acceptable operational force, enhancing the user experience by providing a significant force threshold without excessive effort, and is simple to produce and integrate into existing watch mechanisms.

Implementation Method 1

an elastic blade extending longitudinally and comprising a first end secured to the heel and a second end intended to cooperate with the support element... the blade can be in compression between the heel and the support element during the movement of the support element

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP4407385A1Clock spring of a functional member of a clock mechanism
Publication Date: 2024.07.31 PATEK PHILIPPE SA
  • EP4407385A1 patent drawingFigure 1~2
  • EP4407385A1 patent drawingFigure 3
  • EP4407385A1 patent drawingFigure 4

AI summary

The present invention relates to a watch spring (14) of a functional member (12) of a watch mechanism (10), said functional member (12) being arranged to be mobile in rotation about center O around an axis of rotation Z in a plane XY perpendicular to the axis Z between a minimum angular position in which the functional member (12) is inactive and a maximum angular position taken by the functional member (12) when performing a function to which said functional member (12) is associated, said functional member (12) carrying a support element (16) of circular cross-section extending parallel to the axis Z and intended to be subjected to the action of said watch spring (14),said watch spring (14) comprising a heel (18) intended to be integral with a frame (11) and an elastic blade (18) extending longitudinally and comprising a first end (20a) integral with the heel (18) and a second end (20b) intended to cooperate with the support element (16). The second end (20b) of the blade (20) is arranged to be pivotally mounted on said support element (16), and the watch spring (14) is configured so that the blade (20) can be in compression between the heel (18) and the support element (16) during the movement of the support element (16) at least between two angular positions between the two minimum and maximum angular positions of the functional member (12). The present invention also relates to a watch mechanism comprising a functional member associated with such a watch spring as well as a timepiece comprising such a watch mechanism.