Instantaneous-Jump Calendar Drive Mechanism for Timepiece Torque Management
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Solution Overview
Problem
Existing timepiece calendar systems face challenges in implementing an instantaneous-jump drive device that is compatible with annual, semi-perpetual, or perpetual calendars, leading to energy losses and torque fluctuations, which affect the oscillator's amplitude and are not compact enough.
Innovation Solution
A timepiece calendar system with a date mobile that is step-displaceable relative to a frame, featuring a first drive finger and tooth that can displace the date mobile through multiple steps with a single action, utilizing a desmodromic system with a month cam and cam follower to control the tooth's activation, and including a second drive finger for interacting with a toothset, optimizing the drive mechanism for compactness and reduced energy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a single drive mobile with elastic lever is used for instantaneous date jump, then the date can be changed instantaneously, but the winding of the elastic lever is performed over a limited displacement leading to abrupt torque variations that cause drops in oscillator amplitude
Solution Approach 1:
The patent divides the calendar drive function into two separate drive mobiles: a first drive mobile with a fixed axis for driving the date wheel through a tooth, and a second drive mobile with a displaceable axis for driving the date wheel through an additional tooth. This segmentation allows each drive mobile to be optimized independently, with the second mobile's displaceable axis enabling smoother torque delivery without the abrupt variations caused by winding an elastic lever over limited displacement.
Solution Approach 2:
The patent introduces a month programming cam as an intermediary element that controls the positioning of the second drive mobile's axis. The cam profile dictates the precise angular position of the second mobile throughout the month, enabling it to engage the additional tooth at the correct moment for instantaneous date change while maintaining smooth torque delivery through its displaceable axis configuration.
2Adaptability or versatility
If a month programming cam disposed coaxially with the second mobile is used, then the calendar system can be implemented, but the cam is particularly bulky leaving very little area available for installing a calendar cam and elastic lever
Solution Approach 1:
The patent transitions from a coaxial arrangement where the month programming cam would occupy significant radial space to a configuration where the second drive mobile's axis is displaceable within the plane of the date wheel. This dimensional reorganization allows the month programming cam to control the second mobile's position without requiring bulky coaxial placement, thereby freeing up valuable area within the drive device for other components.
3Ease of operation
If the second finger is elastically returned against the month programming cam under the effect of a return spring, then the finger can be reset, but this leads to premature wear of the drive device and superfluous energy consumption
Solution Approach 1:
The patent removes the return spring mechanism from the drive device. Instead of using an elastic return force, the second drive mobile's axis is allowed to displace freely under the control of the month programming cam's profile. The cam geometry itself provides the positioning and resetting function, eliminating the need for a return spring and its associated energy consumption and wear problems.
Solution Approach 2:
The month programming cam serves a dual function: it not only programs the calendar but also automatically positions and resets the second drive mobile's axis throughout the month. The cam profile itself provides the resetting action through its geometric constraints, making the system self-servicing without requiring additional elastic return mechanisms.
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 enables efficient and compact implementation of an instantaneous-jump drive device that minimizes energy losses at the oscillator, allowing for accurate and reliable date changes without abrupt torque variations, suitable for annual, semi-perpetual, or perpetual calendars.
Implementation Method 1
an activation system (6, 7) for activating the first tooth (51)... a desmodromic system (6, 7) comprising a month cam (7) and a cam follower (6)
Implementation Method 2
The interaction of the cam and the lever enables an instantaneous rotation of the drive mobile... an elastic lever
Implementation Method 3
a first finger provided to actuate one of the thirty-one teeth of a date disc... a first drive finger (21) for driving the date mobile (4)... a first tooth (51) for driving the date mobile (4)
Data Source
AI summary
The movement transmission system (90), notably for a timepiece calendar system (200), includes a driving mobile (4) pivoted about a first axis (A4) and has a driving toothset (42) distributed over a curved profile (43); a driven mobile (7) pivoted about a second axis (A7) and having a driven toothset (72); an intermediate pinion (8) pivoted about a third axis (A8) and having a toothset (81) driven by the driving toothset (42) and driving the driven toothset (72); the toothset (42), the curved profile (43), the driven toothset (72) and the toothset (81) being arranged at a same level or in a same plane, and the driving mobile (4), the driven mobile (7) and the intermediate pinion (8) being arranged so that the driving mobile (4) moves the driven mobile (7) via the intermediate pinion (8) through 1/m steps for at least some steps of the driving mobile (4), m being a real number greater than 1, and so that the driving mobile (4) can define an angular position, with minimum play, of the driven mobile (7) via the pinion (8), whereas the driving mobile (4) is in a given angular position.