Protection for the strips of a mechanical watch resonator

Patent metadata

Field	Value
Publication number	US-10216149-B2
Application number	US-201715793145-A
Country	US
Kind code	B2
Filing date	Oct 25, 2017
Priority date	Nov 16, 2016
Publication date	Feb 26, 2019
Grant date	Feb 26, 2019

Abstract

Strip resonator for a mechanical watch movement, comprising a structure, an oscillating inertial element, and elastic strips forming a flat bearing for the inertial element, and a flat, anti-shock device arranged to protect each strip from rupture in the event of a shock, and including a first prestressed flexible element arranged to allow a variation in length during the expansion or contraction of a strip within a range of lengths corresponding to normal operation of this strip under the action of a stress of intensity lower than a first threshold, and to prevent the expansion or contraction of this strip when it is subjected to a tensile or respectively compressive stress of intensity higher than the first threshold, and the resonator includes, for the three-dimensional anti-shock protection of the strips, in an axial direction perpendicular to a main plane, axial protection means, which include, on the one hand, axial banking members for limiting the axial travel of at least one inertial element, and on the other hand, an axial anti-shock device comprising a second axially prestressed flexible element.

First claim

What is claimed is:

1. A strip resonator for a mechanical movement of a watch arranged to be fixed to a plate of said movement or to form said plate, said resonator including a structure, arranged to be fixed to said plate or to form said plate, and with respect to which structure at least one inertial element is arranged to vibrate and/or to oscillate, and said resonator including at least one elastic strip extending between, at a first end, a first anchorage arranged on said structure, and at a second end, a second anchorage arranged on said at least one inertial element, and said strip being arranged to vibrate essentially in a main plane, wherein said at least one strip forms a bearing for said inertial element in said main plane, and wherein, for the anti-shock protection of said strips comprised therein, said resonator includes, on said first anchorage and/or on said second anchorage, at least one flat anti-shock device, arranged to protect each said at least one strip against rupture in the event of a shock, said flat, anti-shock device including at least a first prestressed flexible element, pretensioned with a prestressing force in said main plane, set at a predetermined safe stress value, wherein, for the three-dimensional anti-shock protection of said strips comprised therein, said resonator includes, in an axial direction perpendicular to said main plane, axial protection means, which include, axial banking members for limiting the axial travel of at least one inertial element, and an axial anti-shock device comprising a second axially prestressed flexible element.

2. The resonator according to claim 1 , wherein said flat, anti-shock device includes at least a first prestressed flexible element arranged to allow a variation in length during the expansion or contraction of said at least one strip within a first range of lengths corresponding to normal operation of said at least one strip under the action of a stress of intensity lower than a threshold, and to prevent the expansion or contraction of said at least one strip outside said first range of lengths (Lmin;
Lmax) when said strip is subjected to a tensile or respectively compressive stress of intensity higher than said threshold.

3. The resonator according to claim 1 , wherein each said strip is protected both by a first said flat, anti-shock device arranged for protection against tensile stress, and by a second said flat, anti-shock device arranged for protection against compressive stress.

4. The resonator according to claim 1 , wherein each said strip is arranged to exert a force returning said at least one inertial element towards a neutral position thereof.

5. The resonator according to claim 4 , wherein said structure is distinct from said plate, and wherein said at least one prestressed flexible element is placed between said structure and said plate, and wherein said flat, anti-shock device includes at least one banking member integral with said plate and arranged to limit the travel of said at least one inertial element.

6. The resonator according to claim 1 , wherein said strip resonator is a rotating resonator.

7. The resonator according to claim 1 , wherein said flat, anti-shock device includes at least a first prestressed flexible element at said first anchorage and another first prestressed flexible element at said second anchorage.

8. The resonator according to claim 1 , wherein said flat, anti-shock device includes at least one stop, arranged to limit the travel of said first end or of said second end, and/or at least one banking member arranged to limit the travel of said at least one inertial element.

9. The resonator according to claim 8 , wherein at least one said first prestressed flexible element is enclosed in a frame including or forming said at least one stop.

10. The resonator according to claim 8 , wherein said at least one first prestressed flexible element is placed between said structure and said at least one inertial element, and wherein said flat, anti-shock device includes at least one banking member integral with said structure and arranged to limit the travel of said at least one inertial element.

11. The resonator according to claim 10 , wherein said at least one said banking member is placed at the centre of rotation of said inertial element in order to minimise disruptive torque in the event of a shock.

12. The resonator according to claim 1 , wherein said at least one flat, anti-shock device includes a base, which is arranged to be fixed to said structure or to said at least one inertial element or to said plate, said base carrying, by means of at least one elastic suspension element, a shuttle to which is fixed said first end or said second end of said at least one strip, and includes at least one said first prestressed flexible element formed by a prestressed spring clip comprising two clip heads arranged to cooperate in a complementary manner, one with a shuttle housing, and the other with a structure housing comprised in said structure or said at least one inertial element or said plate, in a tensile or compressive stressed state of said clip.

13. The resonator according to claim 12 , wherein said base and said shuttle for attachment of said strip are in one piece.

14. The resonator according to claim 13 , wherein said base, said shuttle for attachment of said strip and said clip are in one piece.

15. The resonator according to claim 12 , wherein said resonator comprises a one-piece component which unites all said bases, all said shuttles and all said clips comprised in the flat, anti-shock devices contained in said resonator.

16. The resonator (according to claim 15 , wherein said one-piece component is made of silicon.

17. The resonator according to claim 1 , wherein each strip comprised in said resonator is made of temperature compensated silicon.

18. The resonator according to claim 10 , wherein each strip comprised in said resonator is made of amorphous metal.

19. The resonator according to claim 1 , wherein said resonator includes said flat, anti-shock device and said strips arranged to form two V-shaped pivots mounted head-to-tail, and in combination with a fixed banking member comprised in said structure or said at least one inertial element or said plate, placed at the centre of rotation of said inertial element.

20. The resonator according to claim 1 , wherein said resonator includes a plurality of said strips together forming a crossed strip pivot.

21. The resonator according to claim 20 , wherein said crossed strip pivot includes at least two levels, each comprising, in one piece, said strip, a first prestressed flexible element, and positioning supports for said strips.

22. A timepiece movement including at least one resonator according to claim 1 .

23. The timepiece movement according to claim 22 , wherein said movement includes two said rotating resonators mounted in a tuning fork arrangement to cancel out reaction forces on said plate.

24. The timepiece movement according to claim 22 , wherein said movement includes three said rotating resonators mounted at 120° and phase shifted by one third of a period.

25. A watch including at least one movement according to claim 22 .

Assignees

• Swatch Group Res & Dev Ltd

Inventors

• Winkler Pascal
• Helfer Jean-Luc
• Lechot Dominique
• Born Jean-Jacques

Classifications

• G04B43/002 Primary

  Component shock protection arrangements (shock damping bearings G04B31/02; shock-damping in the case G04B37/04; protection of the pendulum or chime during transport G04B41/00) · CPC title

• G04B17/04 Primary

  Oscillators acting by spring tension · CPC title

• G04B17/045 Primary

  with oscillating blade springs (mechanical oscillations maintained by electro-magnetic means, e.g. tuning forks G04C3/10) · CPC title

• G04B31/02

  Shock-damping bearings {(shock damping in the case G04B37/052, G04B37/055, G04B37/0418)} · CPC title

• G04B17/10

  Oscillators with torsion strips or springs acting in the same manner as torsion strips, e.g. weight oscillating in a horizontal plane {(electrically driven torsion pendulum G04C3/033)} · CPC title