Mechanical timepiece movement provided with a feedback system for the movement

Patent metadata

Field	Value
Publication number	US-9971309-B2
Application number	US-201615196215-A
Country	US
Kind code	B2
Filing date	Jun 29, 2016
Priority date	Aug 11, 2015
Publication date	May 15, 2018
Grant date	May 15, 2018

Abstract

The mechanical timepiece movement includes at least one barrel, a set of gear wheels driven at one end by the barrel, and an escapement mechanism of a local oscillator with a resonator in the form of a sprung balance and a feedback system for the timepiece movement. The escapement mechanism is driven at another end of the set of gear wheels. The feedback system includes at least one precise reference oscillator combined with a frequency comparator to compare the frequency of the two oscillators and a mechanism for regulating the local oscillator resonator to slow down or accelerate the resonator based on the result of a comparison in the frequency comparator.

First claim

What is claimed is:

1. A mechanical timepiece movement, which includes at least one barrel, a set of gear wheels driven at one end by the barrel, and an escapement mechanism of a local oscillator with a resonator in the form of a sprung balance, the escapement mechanism being driven at another end of the set of gear wheels, and a feedback system for the timepiece movement,
wherein the feedback system includes a precise reference oscillator combined with a frequency comparator for comparing the frequency of the two oscillators and a mechanism for regulating the resonator of the local oscillator to slow down or accelerate the resonator based on the result of a comparison in the frequency comparator,
wherein the reference oscillator of the feedback system is excited by magnetic interaction via a rotating exciter wheel in connection with a wheel of the set of gear wheels, and
wherein the exciter wheel is a toothed wheel made of ferromagnetic material, and wherein the reference oscillator includes at least one permanent magnet disposed at a first end of an arm, which is secured via a base to a moving frame of the frequency comparator, the permanent magnet being disposed in proximity to the exciter wheel to be attracted by the passing of each tooth of the rotating exciter wheel and to generate an oscillation at a reference frequency of the reference oscillator.

2. The mechanical timepiece movement according to claim 1 , wherein the reference oscillator includes two arms attached to the base, a first end of each arm respectively carrying a permanent magnet as first and second permanent magnets to form a tuning fork, and wherein the first and second permanent magnets are attracted to the rotating exciter wheel on the passage of each tooth.

3. The mechanical timepiece movement according to claim 2 , wherein the first and second permanent magnets are disposed in proximity to the exciter wheel and in diametrically opposite positions, with the exciter wheel between two permanent magnets.

4. The mechanical timepiece movement according to claim 2 , wherein the exciter wheel includes an odd number N of teeth.

5. The mechanical timepiece movement according to claim 4 , wherein the number N of teeth of the exciter wheel is at least equal to 9.

6. The mechanical timepiece movement according to claim 1 , wherein the moving frame of the frequency comparator is mounted on a plate of the mechanical timepiece movement while being maintained in a defined position via at least one return spring in order to be linearly or angularly displaced as a function of the difference in frequency of the two oscillators.

7. The mechanical timepiece movement according to claim 6 , wherein the moving frame is a hollow wheel disposed coaxially to the exciter wheel, the hollow wheel being mounted for free rotation on the plate by rollers or pins or ball bearings, and wherein the frame is maintained in a defined position via two return springs connected to the frame in diametrically opposite positions.

8. The mechanical timepiece movement according to claim 6 , wherein, as a function of the rotational speed V ex , of the exciter wheel and of the number N of teeth of said exciter wheel defining an excitation frequency ω ext equal to N·V ext , the moving frame of the frequency comparator is arranged to be angularly displaced proportionally to the difference between the oscillation frequency ω 0 of the reference oscillator and the excitation frequency ω ext to control the regulating mechanism and to adjust the oscillation frequency of the sprung balance.

9. The mechanical timepiece movement according to claim 1 , wherein the regulating mechanism includes at least one regulating member connected to the frequency comparator, the at least one regulating member being arranged to be linearly or angularly displaced to adjust the oscillation frequency of the sprung balance.

10. The mechanical timepiece movement according to claim 9 , wherein the regulating member, which is mounted to rotate on a plate, includes a base portion driven at the output of the frequency comparator and a beak-shaped portion capable of moving closer to or further from a last coil of a balance spring of the sprung balance as a function of an angle of rotation of the beak dependent on the frequency comparison in the feedback system.

11. The mechanical timepiece movement according to claim 9 , wherein the regulating member, which is mounted to rotate on a plate, includes a base portion driven at the output of the frequency comparator and an arched portion of complementary shape to an external surface of the balance to vary the friction caused by air on the balance depending on the frequency comparison in the feedback system.

12. The mechanical timepiece movement according to claim 1 , wherein the exciter wheel includes at least portions of ferromagnetic material regularly spaced from each other and disposed over the entire periphery of the exciter wheel to interact magnetically with at least one permanent magnet of the reference oscillator.

13. The mechanical timepiece movement according to claim 1 , wherein the exciter wheel includes at least ferromagnetic portions on or in teeth of the exciter wheel to interact magnetically with at least one permanent magnet of the reference oscillator.

14. The mechanical timepiece movement according to claim 1 , wherein the exciter wheel includes a continuously deposited layer of ferromagnetic material on peripheral teeth of the exciter wheel to interact magnetically with at least one permanent magnet of the reference oscillator.

15. The mechanical timepiece movement according to claim 1 , wherein the exciter wheel includes regularly spaced permanent magnets disposed at the periphery of the exciter wheel to interact magnetically with at least one arm made of ferromagnetic material of the reference oscillator in order to cause said oscillator to oscillate at a determined reference frequency.

16. The mechanical timepiece movement according to claim 1 , wherein the exciter wheel is arranged to excite by magnetic interaction the reference oscillator in the form of a crossed strip resonator.

17. The mechanical timepiece movement according to claim 16 , wherein the crossed strip resonator includes an arched sector or a circular flywheel with a magnetized portion or at least one permanent magnet closely facing the exciter wheel or having portions of ferromagnetic material regularly spaced from each other and arranged at the periphery, wherein the arched sector or the circular flywheel is connected by two first crossed flexible strips to a first moving base plate, the first elastic strips extending at a distance from each other in two parallel planes, wherein the first moving base plate is secured on a second moving base plate, wherein the second base plate is connected by two second crossed flexible strips to a securing plate, which is fixedly mounted on a plate of the mechanical timepiece movement, the second crossed elastic strips extending at a distance from each other in two parallel planes, which are also parallel to the two planes of the first elastic.

18. The mechanical timepiece movement according to claim 17 , wherein the first and second base plates of the frequency comparator are angularly displaced as a function of the frequency comparison of the two oscillators to control the regulating mechanism.

19. The mechanical timepiece movement according to claim 18 , wherein the regulating mechanism includes a regulating beak attached to the first and second base plates, the beak being capable of movi

Assignees

• Eta Sa Mft Horlogere Suisse

Inventors

• Winkler Pascal
• Di Domenico Gianni
• Conus Thierry
• Helfer Jean-Luc

Classifications

• G04C3/06

  using electromagnetic coupling between electric power source and balance · CPC title

• G04B18/04

  Adjusting the beat of the pendulum, balance, or the like, e.g. putting into beat · CPC title

• G04B18/028

  Setting the regulator by means coupled to or depending on another device, e.g. by the time indication setting mechanism (automatic adjustment of the pendulum length G04B17/225, G04B18/003, G04C11/007; automatic adjustment of the regulator for temperature compensation G04B17/22; automatic adjustment of the regulator dependant on the tension of the mainspring G04B1/22) · CPC title

• G04B18/00 Primary

  Mechanisms for setting frequency {(for stabilising frequency G04B17/00)} · CPC title

• G04B17/28

  for the effect of imbalance of the weights, e.g. tourbillon · CPC title