SPIRAL SPRING FOR A HOROLOGICAL RESONATOR MECHANISM PROVIDED WITH MEANS FOR ADJUSTING THE STIFFNESS

Abstract

A spiral spring for a horological resonator mechanism, including a flexible strip (2) coiled on itself into several turns The spring (1) including an element for adjusting its stiffness, which includes a first elongate flexible element (5), and a second elongate flexible element (15) arranged in series with the strip (2), each elongate flexible element (5) connecting the same end (4) of the strip (2) to a fixed support (11), so as to add an additional stiffness to the strip (2), each elongate flexible element (5) preferably having a stiffness higher than that of the strip (2). A prestressing element (6) applies at least two different adjustable efforts, the two efforts being applied on the first elongate flexible element (5) so as to make the stiffness of the first elongate flexible element (5) vary according to the prestress level.

Claims

1. A spiral spring for a horological resonator mechanism, the spiral spring (1, 10) comprising a flexible strip (2) coiled on itself into several turns, the strip (2) having a predefined stiffness, the spiral spring (1, 10) including means for adjusting its stiffness, wherein the adjustment means include a first elongate flexible element (5), and a second elongate flexible element (15) arranged in series with the strip (2), each elongate flexible element (5, 15) connecting the same end (4, 9) of said strip (2) to a fixed support (11, 14), so as to add an additional stiffness to the strip (2), each elongate flexible element (5) preferably having a stiffness higher than that of the strip (2), the adjustment means including prestressing means (6) for applying at least two different adjustable efforts, the two efforts being applied on the first elongate flexible element (5) so as to make the stiffness of the first elongate flexible element (5) vary according to the prestress level.

2. The spiral spring according to claim 1, wherein the first effort is imparted by a first tensile/compressive force directed substantially in the longitudinal direction F.sub.L of the first elongate flexible element (5).

3. The spiral spring according to claim 1, wherein the first effort further exerts a first force directed substantially in a direction substantially orthogonal to the longitudinal direction of the second elongate flexible element (15).

4. The spiral spring according to claim 1, wherein the second effort is imparted by a second force directed substantially in a direction substantially orthogonal F.sub.T to the longitudinal direction of the first elongate flexible element (5).

5. The spiral spring according to claim 4, wherein the second effort further exerts a second tensile/compressive force directed substantially in the longitudinal direction of the second elongate flexible element (15).

6. The spiral spring according to claim 1, wherein each of the first (5) and second (15) elongate flexible elements includes a unique flexible blade (13, 18).

7. The spiral spring according to claim 1, wherein each of the first (5) and second (15) elongate flexible elements includes a pair of main flexible blades (23, 25).

8. The spiral spring according to claim 1, wherein the first (5) and second (15) elongate flexible elements are substantially perpendicular to one another.

9. The spiral spring according to claim 1, wherein the first flexible element (5) is arranged in a radial direction of the spiral spring (1, 10).

10. The spiral spring according to claim 1, wherein the second flexible element (15) is arranged in a direction tangential to the spiral spring (1, 10).

11. The spiral spring according to claim 1, wherein the prestressing means (6) comprise two secondary flexible blades (12, 13) connected at the end (4), each secondary flexible blade (12, 13) being arranged in line with one of the elongate flexible elements (5, 15).

12. The spiral spring according to claim 11, wherein the prestressing means (6) include two rigid bodies (14, 16) each arranged at the end of each secondary flexible blade (12, 13).

13. The spiral spring according to claim 12, wherein the prestressing means (6) include variable support means on each rigid body (14, 16).

14. The spiral spring according to claim 1, wherein the efforts are continuously adjustable by the prestressing means (6).

15. The spiral spring according to claim 1, wherein the first (5) and second (15) flexible elements are arranged at an outer end (4) of the strip (2).

16. The spiral spring according to claim 1, wherein the prestressing means (6) are configured to enable an adjustment of the two efforts at different intensities.

17. A rotary resonator mechanism, in particular for a horological movement, including an oscillating mass, wherein it comprises a spiral spring (1, 10) according to claim 1.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0037] The aims, advantages and features of the present invention will appear upon reading several embodiments given only as non-limiting examples, with reference to the appended drawings wherein:

[0038] FIG. 1 schematically shows a top view of a spiral spring according to a first embodiment of the invention, and

[0039] FIG. 2 schematically shows a top view of a spiral spring according to a second embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0040] Each of FIGS. 1 and 2 shows a schematic illustration of a different embodiment of a spiral spring 1, 10, in particular for a horological resonator mechanism. In this case, the spiral spring extends substantially in the same plane. The spiral spring 1, 10 comprises a flexible strip 2 coiled on itself into several turns, the strip 2 having a predefined stiffness. The spiral spring 1, 10 includes means for adjusting its stiffness. For example, the adjustment means can in particular be actuated when the spiral spring 1, 10 is mounted on a plate of a horological movement, not shown in the figures.

[0041] According to the invention, the adjustment means include first 5 and second 15 elongate flexible elements extending longitudinally. Each flexible element 5, 15 is arranged in series with the strip 2, the first 5 and second 15 flexible elements connect the same end 4 of said strip 2 to a fixed support 11, 14. In other words, the strip 2 is connected to the fixed support 11, 14 only by these flexible elements 5, 15.

[0042] The flexible elements 5, 15 are secured to one of the ends 4 of the strip 2. Preferably, the two flexible elements 5, 15 are arranged perpendicularly to one another.

[0043] The embodiments described hereinbelow comprise flexible elements 5, 15 secured to the outer end 4 of the strip 2. The inner end 19 of the strip 2 is intended to be assembled to a support 3 of an oscillating mass of the resonator 1.

[0044] The flexible elements 5, 15 add additional stiffness to that of the strip 2. Preferably, the flexible elements 5, 15 have a stiffness greater than that of the strip 2. The first flexible element 5 is herein arranged in line with the strip 2, whereas the second flexible element 15 is arranged perpendicularly to the first flexible element 5. Preferably, the adjustment means and the strip 2 are made in one-piece, and possibly formed from the same material.

[0045] Furthermore, the outer end 4 of the strip 2 is herein curved perpendicularly to form an appendix 9. The appendix 9 serves as an attach point, and allows receiving efforts. Preferably, it is substantially rigid, i.e. at least more rigid than the strip 2 and/or the elongate flexible elements 5, 15 to minimise its influence on the stiffness of the strip 2.

[0046] In the first embodiment, each elongate flexible element 5, 15 is a unique flexible blade 13, 15 connecting the appendix 9 to the fixed support 11. The unique first flexible blade 13 is arranged in line with the appendix 9, whereas the unique second flexible blade 13 is arranged in a direction substantially perpendicular to the appendix 9.

[0047] Thus, the unique first flexible blade 13 is arranged according to a radial direction, preferably passing through the centre of the spiral spring 1, in the rest position of the spiral spring 1, whereas the second flexible blade is arranged in a direction tangential to the strip 2.

[0048] In the second embodiment of FIG. 2, each elongate flexible element 5, 15 includes a pair of main blades 23, 25 extending from the appendix 9 up to the fixed support 11. The main blades 23, 25 of each pair deviate from each other from the appendix 9 up to the fixed support 11 and form, for example, an angle comprised between 10 and 40? therebetween.

[0049] The spiral spring 1 further includes prestressing means 6 for applying on at least one of the flexible elements 5, 15, preferably the two flexible elements 5, 15 at least two different efforts. For example, the two efforts are imparted on the first flexible element 5.

[0050] Preferably, the two efforts are a tensile-compressive longitudinal force F.sub.L, and an orthogonal force F.sub.T, which are variable. The longitudinal force F.sub.L is directed according to the longitudinal direction of the first flexible element 5, whereas the orthogonal force F.sub.T, is directed according to a direction perpendicular to the longitudinal direction of the first flexible element 5, the two forces preferably belonging to the plane of the spiral spring 1, 10. Thus, it is possible to modify the stiffness of the first flexible element 5, and thus adjust running of the spiral spring 1, 10, in particular to improve the accuracy of running of the movement.

[0051] The first flexible element 5 is acted upon to modify its stiffness without directly acting on the strip 2. However, during oscillations, the end 4 of the strip 2 may be movable.

[0052] In addition, the longitudinal F.sub.L and orthogonal F.sub.T forces are continuously adjustable by the prestressing means 6. In other words, the forces F.sub.L and F.sub.T are not restricted to discrete values. Thus, it is possible to finely adjust the stiffness of the flexible element 5 with great accuracy.

[0053] Furthermore, the prestressing means 6 are configured to modify the stiffness of the second flexible element 15.

[0054] Indeed, the first effort further exerts a first force directed substantially in a direction substantially orthogonal to the longitudinal direction of the second elongate flexible element 15. Since the two flexible elements 5, 15 are arranged perpendicularly to one another, a longitudinal force applied on one of the elongate flexible elements 5, 15, generates a substantially orthogonal force applied on the other flexible element.

[0055] Similarly, the second effort further exerts a second tensile/compressive force directed substantially in the longitudinal diction of the second elongate flexible element 15.

[0056] To apply these adjustable forces, the prestressing means 6 comprise two means for applying a force on the elongate flexible elements 5, 15.

[0057] Each of the application means comprises two secondary flexible blades 12, 13. Each secondary flexible blade 12, 13 is arranged in line with the elongate flexible element 5, 15, and is fastened at the other side of the appendix 9.

[0058] The two secondary flexible blades 12, 13 are arranged perpendicularly to one another.

[0059] Alternatively, the secondary blades 12, 13, may be replaced with conventional springs.

[0060] Each secondary flexible blade 12, 13 is provided with a rigid body 14, 16 at the free end. The rigid body 14, 16 enables the application of a variable force on the secondary flexible body 12, 13 in order to adjust the force transmitted to the elongate flexible element 5, 15.

[0061] By moving the rigid bodies 14, 16, a variable longitudinal force F.sub.L and a variable orthogonal force F.sub.T are applied on the appendix 9, according to each direction of movement of each rigid body 19, 21. Thus, the stiffness of the elongate flexible elements 5, 15 is modified. By moving the rigid bodies 19, 21, the value of the force exerted on the unique flexible blade 15 is modified.

[0062] The prestressing means 6 further include variable support means on the rigid body 14, 16. By actuating the support means, the rigid body 14, 16 moves, so that the secondary flexible blade 12, 13 is more or less bent, and consequently transmits a more or less substantial force on the elongate flexible element 5, 15. Thus, the rigidity of the elongate flexible element 5, 15 is modified, so that running of the spiral spring is modified, and could be adjusted.

[0063] For example, the variable support means consist of a screw 24 in contact with the rigid body 14, 16, and arranged longitudinally according to the direction of the secondary flexible blade 12, 13. Thus, by moving the screw 24, the secondary flexible blades 12, 13 exert a more or less substantial force on the appendix 9, and therefore on the elongate flexible elements 5, 15.

[0064] Alternatively, the variable support means comprise a spring fastened at one side to the rigid body, and a movable body arranged at the other end of the spring. Thus, by moving the movable body, the spring exerts a more or less substantial force on the secondary flexible blade.

[0065] In another variant, the prestressing means include a first magnet arranged on the rigid body, and a second movable magnet arranged at a distance from the rigid body. Thus, by modifying the distance of the second magnet with respect to the first magnet, the force applied on the secondary flexible blade is modified.

[0066] Alternatively, it is possible to use a pivoting lever assembled to the rigid body by a first end, the other end being free and serving as a means for actuating the lever by moving said free end.

[0067] Preferably, the prestressing means are configured to enable an adjustment of the two efforts, herein the two longitudinal tensile/compressive forces at different intensities. Thus, a first application means enables an adjustment in a wider setting range, and a second application means enables an adjustment in a finer setting range.

[0068] To this end, the secondary flexible blades 12, 13 have, for example, different sections or lengths. Alternatively, the variable support means on the rigid body 14, 16 are configured to obtain different setting ranges, for example with a different screw pitch.

[0069] The invention also relates to a horological movement comprising such a spiral spring. In particular, the spiral spring is used to actuate the movement of a balance.

[0070] Of course, the invention is not limited to the embodiments described with reference to the figures and variants could be considered without departing from the scope of the invention.

[0071] As regards the longitudinal element, the flexible blades described in the different embodiments of the spiral spring, may be continuous flexible blades, as is generally the case in the figures, or blades with rigid sections and flexible necks connecting the sections.

[0072] Furthermore, the unique flexible blade may be directed according to directions other than radial and orthogonal with respect to the spiral spring. Thus, it may be directed according to any direction comprised between the radial and orthogonal directions.