Watch Jumper Synchronization Cam Reduces Drive Torque

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Solution Overview

Problem

Existing systems for driving and positioning jumping-type display mobiles in watchmaking face challenges in maintaining secure positioning while minimizing disturbances during transitions between indexed positions, often resulting in unacceptable loss of amplitude or movement cessation due to high stiffness and angular displacement of the spring member.

Innovation Solution

A drive and positioning system incorporating a synchronization cam and a feeler that opposes the moment induced by the spring force, reducing the torque required to drive the driven wheel by exerting a counter-moment when the drive members cooperate with the driven wheel, thereby minimizing disturbances and maintaining secure positioning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the stiffness and angular displacement of the spring member are increased to improve positioning security, then the holding torque increases, but the torque required to lift the jumper increases causing unacceptable amplitude loss or movement cessation

Engineering Contradiction:

Improvepositioning securityVSAvoidamplitude loss

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The synchronization cam and feeler mechanism apply a counter-moment to the jumper before the spring member needs to lift it fully. This preliminary anti-action reduces the peak torque requirement by opposing the spring's moment in advance, allowing the system to maintain high spring stiffness for positioning security while reducing the energy penalty during transitions

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The feeler acts as an intermediary between the synchronization cam and the jumper. It transmits the counter-moment from the cam to the jumper, enabling precise control of the torque applied to the jumper during the transition phase without directly connecting the cam to the jumper

Inventive Principle:

Principle #24Intermediary (Mediator)

2Use of energy by moving object

If the spring member stiffness is reduced to decrease torque during lifting, then amplitude loss is reduced, but positioning security is compromised

Engineering Contradiction:

Improveamplitude lossVSAvoidpositioning security

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The system dynamically adjusts the net moment on the jumper through the synchronization cam and feeler mechanism. During positioning phases, the spring member maintains high stiffness for secure holding. During transitions, the feeler applies a counter-moment that dynamically reduces the peak torque requirement, allowing the spring to be stiffer without causing excessive amplitude loss

Inventive Principle:

Principle #15Dynamics

3Measurement precision

If the spring member angular displacement is increased to improve positioning accuracy, then positioning precision improves, but the torque required to drive the driven wheel increases causing movement cessation

Engineering Contradiction:

Improvepositioning precisionVSAvoiddriving torque

Core Design Contradiction:

Measurement precisionVSPower

Solution Approach 1:

The synchronization cam and feeler apply a counter-moment to the jumper in advance during the transition phase, opposing the spring's restoring moment. This preliminary anti-action reduces the peak torque requirement, allowing the spring member to have larger angular displacement for better positioning precision without causing the driven wheel to stall

Inventive Principle:

Principle #9Preliminary anti-action

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 system reduces the maximum torque required to drive the driven wheel, ensuring stable and secure positioning without compromising the holding force of the spring member, thus preventing unacceptable amplitude loss or movement cessation.

Implementation Method 1

a spring member arranged to press the positioning zone against the driven wheel and position it angularly

Methodology Applied

Scientific EffectElastic force: Elasticity

Implementation Method 2

said synchronization cam and said feeler being arranged so as to exert on the jumper, at least when the n drive members cooperate with the driven wheel, a force whose moment relative to the axis of the jumper opposes the moment induced by the force exerted by the spring

Methodology Applied

Scientific EffectMechanical force: Mechanical Force

Data Source

PatentEP3428738B1Drive and positioning system and jumper for implementing said system

Publication Date: 2022.02.16 MFG & FAB DE MONTRES & DE CHRONOMETRES ULYSSE NARDIN LE LOCLE SA

Figure 1
Figure 2

AI summary

The invention relates to a drive and positioning system for a display mobile, comprising: - a driving wheel (10) having n drive members (14), - a driven wheel (12) intended to be driven by the n drive members (14), - a jumper (16) comprising a positioning zone (18) and a spring member (20) arranged to press the positioning zone (18) against the driven wheel (12) and position it angularly.According to the invention, this system comprises a synchronizing cam (24) driven by the driving wheel (10) and a feeler (26) having one end maintained in contact with the periphery of the synchronizing cam (24) and cooperating with the jumper (16), said synchronizing cam (24) and said feeler (26) being arranged so as to exert on the jumper (16), at least when the n drive members (14) cooperate with the driven wheel (12), a force whose moment with respect to the axis of rotation of the jumper opposes the moment induced by the force exerted by the spring, with respect to said axis of rotation of the jumper. An independent claim relates to a jumper adapted for this drive system.