Timepiece oscillator with flexure bearings having a long angular stroke

Patent metadata

Field	Value
Publication number	US-10895845-B2
Application number	US-201916439798-A
Country	US
Kind code	B2
Filing date	Jun 13, 2019
Priority date	Jun 25, 2018
Publication date	Jan 19, 2021
Grant date	Jan 19, 2021

Abstract

A mechanical timepiece oscillator including, between a first element and a second inertial element, more than two distinct flexible strips returning the inertial element to a rest position in an oscillation plane, wherein the projections of these strips cross each other, at a point, through which passes the axis of pivoting of the second solid inertial element, and the height to thickness aspect ratio is less than 10 for each strip.

First claim

The invention claimed is:

1. A mechanical timepiece oscillator comprising:
a flexure bearing disposed between a first rigid support element and a solid inertial element and including more than two first flexible strips which support said solid inertial element and are arranged to return said solid inertial element to a rest position,
wherein said solid inertial element is arranged to oscillate angularly in an oscillation plane about said rest position, said more than two first flexible strips do not touch each other and their projections onto said oscillation plane cross, in the rest position, at a crossing point, in proximity to which or through which passes an axis of rotation of said solid inertial element perpendicularly to said oscillation plane, and embedding points of said more than two first flexible strips in said first rigid support element and said solid inertial element define two strip directions parallel to said oscillation plane, each strip of the more than two first flexible strips has an aspect ratio RA=H/E, where H is a height of said strip perpendicularly both to the oscillation plane and to an elongation of said strip along a length L, and wherein E is a thickness of said strip in the oscillation plane and perpendicularly to the elongation of said strip along said length L, wherein said aspect ratio RA=H/E is less than 10 for each said strip.

2. The mechanical oscillator according to claim 1 , wherein said oscillator includes a first number N1 of said more than two first flexible strips as primary strips extending in a first strip direction, and a second number N2 of said more than two first flexible strips as secondary strips extending in a second strip direction, said first number N1 and said second number N2 each being greater than or equal to two.

3. The mechanical oscillator according to claim 2 , wherein said first number N1 is equal to said second number N2.

4. The mechanical oscillator according to claim 2 , wherein said oscillator includes at least one pair formed of said primary strip extending in a first strip direction, and said secondary strip extending in a second strip direction and wherein, in each pair, said primary strip is identical to said secondary strip except as regards orientation.

5. The mechanical oscillator according to claim 4 , wherein said oscillator includes only said pairs each formed of said primary strip extending in a first strip direction, and said secondary strip extending in a second strip direction, and wherein, in each pair, said primary strip is identical to said secondary strip, except as regards orientation.

6. The mechanical oscillator according to claim 2 , wherein said oscillator includes at least one group of strips formed of said primary strip extending in a first strip direction, and said secondary strip extending in a second strip direction and wherein, in each said group of strips, elastic behavior of said primary strip is identical to the elastic behavior resulting from a plurality of secondary strips including the secondary strip except as regards orientation.

7. The mechanical oscillator according to claim 1 , wherein said first strips are straight strips.

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

9. The mechanical oscillator according to claim 8 , wherein said vertex angle is less than or equal to 50°, and wherein said embedding point ratio is comprised between 0.25 and 0.75 inclusive.

10. The mechanical oscillator according to claim 9 , wherein said vertex angle is less than or equal to 40°, and wherein said embedding point ratio is comprised between 0.30 and 0.70 inclusive.

11. The mechanical oscillator according to claim 10 , wherein said vertex angle is less than or equal to 35°, and wherein said embedding point ratio is comprised between 0.40 and 0.60 inclusive.

12. The mechanical oscillator according to claim 8 , wherein said vertex angle is less than or equal to 30°.

13. The mechanical oscillator according to claim 1 , wherein an apex angle and a ratio X=D/L satisfy a relation h1(D/L)<α<h2(D/L), where,
for 0.2≤X<0.5:
h 1( X )=116−473*( X+ 0.05)+3962*( X+ 0.05) 3 −6000*( X+ 0.05) 4 ,

h 2( X )=128−473*( X− 0.05)+3962*( X− 0.05) 3 −6000*( X− 0.05) 4 ,

for 0.5<X≤0.8:
h 1( X )=116−473*(1.05− X )+3962*(1.05− X ) 3 −6000*(1.05− X ) 4 ,

h 2( X )=128−473*(0.95− X )+3962*(0.95− X ) 3 −6000*(0.95− X ) 4 .

14. The mechanical oscillator according to claim 1 , wherein a center of mass of said oscillator in its rest position is separated from said crossing point by an interval which is comprised between 10% and 20% of a total length of the projection, onto said oscillation plane, of said strip.

15. The mechanical oscillator according to claim 14 , wherein said interval is comprised between 12% and 18% of a total length of the projection, onto said oscillation plane, of said strip.

16. The mechanical oscillator according to claim 1 , wherein said first strips and their embedding points define together a pivot which, in projection onto said oscillation plane, is symmetrical with respect to an axis of symmetry passing through said crossing point.

17. The mechanical oscillator according to claim 16 , wherein, in the rest position, in projection onto said oscillation plane, a center of mass of said solid inertial element is located on said axis of symmetry of said pivot.

18. The mechanical oscillator according to claim 17 , wherein, in projection onto said oscillation plane, a center of mass of said solid inertial element is at a non zero distance from said crossing point corresponding to an axis of rotation of said solid inertial element, which non zero distance is comprised between 0.1 times and 0.2 times a total length of the projection, onto said oscillation plane, of said strip.

19. A timepiece movement comprising the mechanical oscillator according to claim 1 .

20. A watch comprising the timepiece movement according to claim 19 .

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

• G04B15/14

  Component parts or constructional details, e.g. construction of the lever or the escape wheel {(assembly and manufacture of the spring G04B1/145; assembly and manufacture of components, e.g. pinions, spindles G04B13/02; lubrication of clockwork bearings G04B31/008; oils for clockwork bearings in general G04B31/08)} · CPC title

• G04B31/00

  Bearings; Point suspensions or counter-point suspensions; Pivot bearings; Single parts therefor (bearings in general F16C {; manufacture and composition of springs G04B1/145; suspension of oscillating weights G04B5/18; suspension of a pendulum G04B17/02; bearings for electrical measurement apparatus G01R1/10, G01R1/12, G01R11/12, G01R11/14; inserting jewels A44C17/04; inserting cutting diamonds B23P5/00; devices for fixation of bearing jewels, bearing sleeves, or the like G04D3/04}) · CPC title

• G04B31/02

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

• G04B17/045 Primary

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

• G04C3/101

  constructional details · CPC title