Timepiece oscillator with flexure bearings having a long angular stroke

Patent metadata

Field	Value
Publication number	US-10935933-B2
Application number	US-201916511191-A
Country	US
Kind code	B2
Filing date	Jul 15, 2019
Priority date	Jul 24, 2018
Publication date	Mar 2, 2021
Grant date	Mar 2, 2021

Abstract

A mechanical timepiece oscillator includes, between a support and an inertial element, a flexure bearing with flexible strips crossed in projection, including, superposed, an upper level that includes, between an upper support and an upper inertial element, an upper primary strip in a first direction and an upper secondary strip in a second direction, and a lower level that includes, between a lower support and a lower inertial element, a lower primary strip in the first direction and a lower secondary strip in the second direction. The upper level and lower level include, between the support and the upper or respectively lower support, a translational table with an elastic connection along one or two axes of freedom in the oscillation plane, of lower stiffness than that of each flexible strip.

First claim

The invention claimed is:

1. A mechanical timepiece oscillator, comprising:
a flexure bearing mechanism disposed between a first rigid support element directly or indirectly fixed to a plate and a solid inertial element, the flexure bearing mechanism including at least two first flexible strips which support the solid inertial element and are configured to return the solid inertial element to a rest position, wherein
the solid inertial element is configured to oscillate angularly in an oscillation plane about the rest position,
the first flexible strips do not touch each other,
projections of the first flexible strips onto the oscillation plane cross, in the rest position, at a crossing point,
an axis of rotation of the solid inertial element passes proximate to the crossing point, the axis of rotation being perpendicular to the oscillation plane,
the flexure bearing mechanism includes at least one upper level and at least one lower level superposed on each other,
the at least one upper level includes, between an upper support and the solid inertial element, at least one upper primary strip extending in a first upper strip direction and one upper secondary strip extending in a second upper strip direction, the at least one upper primary strip and the one upper secondary strip being projected onto and crossed at an upper crossing point,
the at least one lower level includes, between a lower support and the solid inertial element, at least one lower primary strip extending in a first lower strip direction and one lower secondary strip extending in a second lower strip direction, the at least one lower primary strip and the one lower secondary strip being projected onto and crossed at a lower crossing point,
the upper level includes, between the plate and the upper support, an upper translational table,
the lower level includes, between the plate and the lower support, a lower translational table,
the upper translational table and the lower translational table comprise at least one elastic connection along one or two axes of freedom in the oscillation plane, and
a stiffness of the at least one elastic connection is lower than a stiffness of the upper level and a stiffness of the lower level.

2. The mechanical timepiece oscillator according to claim 1 , wherein
the at least one elastic connection along one or two axes of freedom in the oscillation plane is an elastic connection along X and Y axes of bisectors of angles formed between the projections of the first flexible strips of the flexure bearing mechanism onto a common parallel plane.

3. The mechanical timepiece oscillator according to claim 1 , wherein
a first strip direction and a second strip direction, parallel the oscillation plane, form therebetween, in the rest position, a vertex angle projected onto the oscillation plane, and
a position of the crossing point is defined by an embedding point ratio X=D/L, where
D is a distance between the projection, onto the oscillation plane, of one of two embedding points of the first flexible strips in the first rigid support element and the crossing point,
L is a total length of the projection, onto the oscillation plane, of the first flexible strips,
the centre of mass of the oscillator in the rest position is separated from the crossing point by an offset,
the offset is between 12% and 18% of the total projected length L, onto the oscillation plane, of the first flexible strips,
the vertex angle is less than or equal to 60°, and
the embedding point ratio is between 0.15 and 0.85 inclusive for each of the first flexible strips.

4. The mechanical timepiece oscillator according to claim 1 , wherein
each of the first flexible strips has an aspect ratio RA=H/E, where
H is a height of the first flexible strip, the height being perpendicular both to the oscillation plane and to an elongation of the first flexible strip along a length L,
E is a thickness of the first flexible strip in the oscillation plane, the first flexible strip being perpendicular to the elongation of the first flexible strip along the length L,
the aspect ratio RA=H/E is less than 10 for the first flexible strip, and
a total number of the first flexible strips is greater than two.

5. The mechanical timepiece oscillator according to claim 4 , wherein
the oscillator includes a first number of the first flexible strips, called primary strips, extending in the first strip direction, and a second number of the first flexible strips called secondary strips extending in the second strip direction, and
the first number and the second number are each greater than or equal to two.

6. The mechanical timepiece oscillator according to claim 5 , wherein
the first number is equal to the second number.

7. The mechanical timepiece oscillator according to claim 5 , wherein
the oscillator includes at least one pair formed of one of the primary strips extending in the first strip direction, and one of the secondary strips extending in the second strip direction, and
in each of the at least one pair, the one of the primary strips is identical to the one of the secondary strips, except as regards orientation.

8. The mechanical timepiece oscillator according to claim 7 , wherein
the oscillator includes only pairs formed of one of the primary strips extending in the first strip direction, and one of the secondary strips extending in the second strip direction, and
in each of the pairs, the one of the primary strips is identical to the one of the secondary strips, except as regards orientation.

9. The mechanical timepiece oscillator according to claim 5 , wherein
the oscillator includes at least one group of strips formed of one of the primary strips extending in the first strip direction, and a plurality of the secondary strips extending in the second strip direction, and
in each of the at least one group of strips, an elastic behaviour of the one of the primary strips is identical to an elastic behaviour resulting from the plurality of the secondary strips except as regards orientation.

10. The mechanical timepiece oscillator according to claim 1 , wherein
a first strip direction and a second strip direction, parallel the oscillation plane, form therebetween, in the rest position, a vertex angle projected onto the oscillation plane, and
a position of the crossing point is defined by an embedding point ratio X=D/L, where
D is a distance between the projection, onto the oscillation plane, of one of the two embedding points of the first flexible strips in the first rigid support element and the crossing point,
L is a total length of the projection, onto the oscillation plane, of the first flexible strips in elongation of the first flexible strips, and
the embedding point ratio between 0.15 and 0.49 inclusive or between 0.51 and 0.85 inclusive.

11. The mechanical timepiece oscillator according to claim 10 , wherein
the vertex angle is less than or equal to 50°, and
the embedding point ratio is between 0.25 and 0.75 inclusive.

12. The mechanical timepiece oscillator according to claim 11 , wherein
the vertex angle is less than or equal to 40°, and
the embedding point ratio is between 0.30 and 0.70 inclusive.

13. The mechanical timepiece oscillator according to claim 12 , wherein
the vertex angle is less than or equal to 35°, and
the embedding point ratio is between 0.40 and 0.60 inclusive.

14. The mechanical timepiece oscillator according to claim 10 , wherein
the vertex angle is less than or equal to 30°.

15. The mechanical timepiece oscillator according to claim 10 , wherein
the vertex angle and the e

Assignees

• Swatch Group Res & Dev Ltd

Inventors

• Di Domenico Gianni
• Cusin Pierre
• Helfer Jean-Luc
• Gandelhman Alex
• Winkler Pascal
• Hinaux Baptiste
• Lechot Dominique
• Matthey Olivier
• Klinger Laurent
• Favre Jerome

Classifications

• G04B17/045 Primary

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

• G04B17/10 Primary

  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