Calendar Mechanism Movable Tooth Month Correction

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Solution Overview

Problem

Existing watch movement calendar mechanisms are complex, large in size, and prone to wear, making them unreliable and difficult to produce and assemble.

Innovation Solution

A counting device with a control mechanism featuring a mobile tooth system rotatably mounted on a first plate, utilizing a cam of variable radius for radial guidance and elastic members to define tooth positions, reducing bulk and complexity while accounting for month duration differences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple satellite wheels and sliding elements are used to control the program wheel, then the calendar mechanism can accurately account for month durations, but the device complexity and size increase substantially

Engineering Contradiction:
Improveaccuracy of month duration accountingVSAvoidnumber of wheels and components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts the essential function of month duration control from the complex multi-wheel system and implements it through a single movable tooth on the program wheel that selectively engages with the fixed toothed element. This removes unnecessary satellite wheels and sliding elements while preserving the core functionality of accounting for 28-31 day months.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using multiple active components to drive the program wheel through complex gear trains, the invention inverts the approach by using a single movable tooth that passively engages with the fixed toothed element only when needed. The program wheel is driven by the fixed element rather than by active satellite wheels, simplifying the mechanism.

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

2Reliability

If multiple wheels are stacked on the program carriage, then the calendar mechanism can provide comprehensive date control, but the program carriage diameter and thickness increase

Engineering Contradiction:
Improvedate control accuracyVSAvoidprogram carriage size
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The invention removes the stacked multi-wheel structure from the program carriage, retaining only the essential program wheel with its single movable tooth. This extraction eliminates the need for multiple stacked wheels while preserving date control functionality, thereby reducing the carriage volume.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention combines the functions of multiple separate wheels into a single integrated program wheel with a movable tooth. The program wheel simultaneously handles day counting and month duration adjustment through the selective engagement of its movable tooth with the fixed toothed element, eliminating the need for separate stacked wheels.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If multiple correction gears with offset axes are used, then short month correction can be achieved, but the assembly complexity increases

Engineering Contradiction:
Improveshort month correction accuracyVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The invention extracts the short month correction function from the multi-gear system with offset axes and implements it through the selective engagement of the movable tooth with the fixed toothed element. This eliminates the need for multiple correction gears with complex offset relationships, simplifying assembly.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The program wheel with its movable tooth serves multiple functions: it counts days, provides short month correction, and accounts for month duration variations. This single multi-functional component replaces the specialized correction gears, reducing assembly complexity while maintaining correction accuracy.

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

4Reliability

If numerous wheels and components are used in the calendar mechanism, then comprehensive date and month control is achieved, but the mechanism becomes more prone to wear and less reliable

Engineering Contradiction:
Improvedate and month control capabilityVSAvoidwear and malfunction risk
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention removes numerous wheels and components from the mechanism, retaining only the essential program wheel with its movable tooth and the fixed toothed element. This drastic reduction in component count eliminates many potential wear points and failure modes while preserving date and month control capabilities.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The movable tooth on the program wheel automatically engages with the fixed toothed element based on the program wheel's rotational position, providing self-regulating month duration control without requiring additional active control components. This passive engagement mechanism reduces wear compared to actively controlled multi-wheel systems.

Inventive Principle:
Principle #25Self-service

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 results in a more reliable, compact calendar mechanism that accurately accounts for month durations without the need for numerous components, reducing wear and simplifying assembly.

Implementation Method 1

a cam of variable radius arranged to cooperate with the movable tooth and to define its position, retracted or extracted, according to the angular orientation of the cam

Methodology Applied
Scientific EffectCam mechanism: Cam

Implementation Method 2

an elastic member arranged to act on the movable tooth and to maintain it in a retracted position

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3008523B1Calendar mechanism for a clock movement
Publication Date: 2020.01.22 CARTIER INTERNATIONAL AG
  • EP3008523B1 patent drawingFigure 1
  • EP3008523B1 patent drawingFigure 2
  • EP3008523B1 patent drawingFigure 3

AI summary

The present invention relates to a counting device, for a calendar mechanism of a clock movement, comprising a stationary toothed part (250, 550) and a program train (222, 522) which are coaxial, the latter comprising a first rotary plate (224, 524) having outer teeth (225, 525), a device for correcting short months which includes at least one tooth (228, 528) that is movable between a retracted position and an extracted position, in which said tooth is added to the teeth (225, 525) of the first plate, and a control mechanism (238, 248, 538, 548) arranged such as to define the position of the movable tooth (228, 528) and including at least one wheel (248, 548) arranged such as to engage with the stationary toothed part (250, 550). Said device is characterized in that the control mechanism comprises a train for the months (238, 538), which is rotatably mounted on the first plate (224, 524), which includes teeth (245, 545) that have a kinematic connection with the wheel (248, 548), and which supports a cam (240, 540) that is arranged such as to engage with the movable tooth (228, 528) and define the position thereof.