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 strip (2) having a predefined stiffness. The spring (1) include an element for adjusting its stiffness, including a unique elongate flexible element (5) arranged in series with the strip (2), and connecting one end (4) of said strip (2) to a fixed support (11), to add additional stiffness. The flexible element (5) has a stiffness higher than that of the strip (2). A prestressing element (6) applies two different efforts on the element (5), and includes a first lever (8) attached to the end (4) of the strip (2) to allow adjusting a first effort, and a second lever (8) also attached to the end (4) of the strip (2) to adjust a second effort independently of the first effort.

Claims

1. A spiral spring for a horological resonator mechanism, the spiral spring (1) comprising a flexible strip (2) coiled on itself into several turns, the strip (2) having a predefined stiffness, the spiral spring (1) including means for adjusting its stiffness, the adjustment means including a unique elongate flexible element (5) arranged in series with the strip (2), the elongate flexible element (5) connecting one end (4, 19) of said strip (2) to a fixed support (11), so as to add an additional stiffness to the strip (2), the elongate flexible element (5) preferably having a stiffness higher than that of the strip (2), the adjustment means including prestressing means (6) to apply at least two different efforts on the elongate flexible element (5), wherein the prestressing means (6) include a first lever (8) attached to the end (4, 19) of the strip (2) so as to allow adjusting a first effort, and a second lever (8) also attached to the end (4, 19) of the strip (2) so as to adjust a second effort independently of the first effort.

2. The spiral spring according to claim 1, wherein the first effort is imparted, either by a first tensile/compressive force directed substantially in the longitudinal direction F.sub.L1 of the elongate flexible element (5), or by a first force directed substantially in a direction substantially orthogonal F.sub.T1 to the longitudinal direction of the elongate flexible element (5), or by a first torque M.sub.1, preferably a bending moment, so as to make the stiffness of the elongate flexible element (5) vary according to the prestress level.

3. The spiral spring according to claim 1, wherein the second effort is imparted either by a second tensile/compressive force directed substantially in the longitudinal direction F.sub.L2 of the elongate flexible element (5), or by a second force directed substantially in a direction substantially orthogonal F.sub.T2 to the longitudinal direction of the elongate flexible element (5), or by a second torque M.sub.2, preferably a bending moment, so as to make the stiffness of the elongate flexible element (5) vary according to the prestress level.

4. The spiral spring according to claim 1, wherein the prestressing means (6) are configured to exert a third effort on the elongate flexible element (5), the third effort being imparted, respectively at the first effort, either by the first tensile/compressive force F.sub.L1, or by the substantially orthogonal first force F.sub.T1, or by the first torque M.sub.1.

5. The spiral spring according to claim 4, wherein the third effort is adjustable by the first lever (8).

6. The spiral spring according to claim 1, wherein the prestressing means (6) are configured to exert a fourth effort on the elongate flexible element (5), the fourth effort being imparted, respectively at the second effort, either by the second tensile/compressive force F.sub.L2, or by the substantially orthogonal second force F.sub.T2, or by the second torque M.sub.2.

7. The spiral spring according to claim 6, wherein the fourth effort is adjustable by the second lever (15).

8. The spiral spring according to claim 1, wherein the prestressing means (6) are configured to exert a fifth effort on the elongate flexible element (5), the fifth effort being imparted, respectively at the first effort and at the third effort, either by the first tensile/compressive force F.sub.L1, or by the substantially orthogonal first force F.sub.T1, or by the first torque M.sub.1.

9. The spiral spring according to claim 8, wherein the fifth effort is adjustable by the first lever (8).

10. The spiral spring according to claim 1, wherein the prestressing means (6) are configured to exert a sixth effort on the elongate flexible element (5), the sixth effort being imparted, respectively to the second effort and at the fourth effort, either by the second tensile/compressive force F.sub.L2, or by the substantially orthogonal second force F.sub.T2, or by the second torque M.sub.2.

11. The spiral spring according to claim 10, wherein the sixth effort is adjustable by the second lever (15).

12. The spiral spring according to claim 1, wherein the elongate flexible element (5) is a unique flexible blade (13).

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

14. The spiral spring according to claim 1, wherein the first (8) and second (15) levers are flexible.

15. The spiral spring according to claim 1, wherein the first lever (8) comprises a first free end (12) which can be actuated by a movement of said first free end (12) in order to apply said efforts on the elongate flexible element (5), and the second lever (15) comprises a second free end (16) which can be actuated by a movement of said second free end (16) in order to apply said efforts on the elongate flexible element (5).

16. The spiral spring according to claim 1, wherein the first (8) and second (15) levers are configured to enable an adjustment of the effort(s) at different intensities.

17. The spiral spring according to claim 16, wherein the first (8) and second (15) levers have a section or a stiffness different from one another.

18. The spiral spring according to claim 1, wherein the effort(s) is/are continuously adjustable by the prestressing means (6).

19. The spiral spring according to claim 1, wherein the flexible element (5) and the levers (8, 15) are arranged at an outer end (4) of the strip (2).

20. A rotary resonator mechanism for a horological movement, including an oscillating mass, wherein the resonator mechanism includes the spiral spring (1) according to claim 1.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0045] 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:

[0046] FIG. 1 schematically shows a top view of a spiral spring according to an embodiment of the invention, and

[0047] FIG. 2 schematically shows an enlarged top view of the appendix and of the efforts applied on the appendix according to the first embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0048] FIG. 1 shows a schematic illustration of an embodiment of a spiral spring 1, in particular for a horological resonator mechanism. In this case, the spiral spring 1 extends substantially in the same plane. The spiral spring 1 comprises a flexible strip 2 coiled on itself into several turns, the strip 2 having a predefined stiffness. The spiral spring 1 includes means for adjusting its stiffness. For example, the adjustment means can in particular be actuated when the spiral spring 1 is mounted on a plate of a horological movement, not shown in the figures.

[0049] According to the invention, the adjustment means include an elongate flexible element 5 extending longitudinally, which is arranged in series with the strip 2, the flexible element 5 connecting one end 4 of said strip 2 to a fixed support 11. In other words, the strip 2 is connected to the fixed support 11 only by this flexible element 5.

[0050] The flexible element 5 is secured to one of the ends 4 of the strip 2. The embodiments described hereinbelow comprise a flexible element 5 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.

[0051] The flexible element 5 adds additional stiffness to that of the strip 2. Preferably, the flexible element 5 has a stiffness greater than that of the strip 2. The flexible element 5 is herein arranged in line with the strip 2. Preferably, the adjustment means 5 and the strip 2 are made in one-piece, and possibly formed from the same material.

[0052] Furthermore, the end 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 element 5, to minimise its influence on the stiffness of the strip 2.

[0053] Preferably, the longitudinal flexible element 5 is a unique flexible blade 13, 15 connecting the appendix 9 to the fixed support 11, 14.

[0054] The unique flexible blade 13 is arranged in line with the appendix 9. The unique flexible blade 13 is arranged in a direction perpendicular to the end of the strip 2.

[0055] Thus, the unique 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.

[0056] The spiral spring 1 further includes prestressing means 6 to apply on the flexible element 5 at least two different efforts, a first effort and a second effort.

[0057] The first effort is imparted, either by a first tensile/compressive force directed substantially in the longitudinal direction F.sub.L1 of the elongate flexible element, or by a first force directed substantially in a direction substantially orthogonal F.sub.T1 to the longitudinal direction of the elongate flexible element, or by a first torque M.sub.1, preferably a bending moment, so as to make the stiffness of the elongate flexible element vary according to the prestress level.

[0058] The second effort is imparted by a second tensile/compressive force directed substantially in the longitudinal direction F.sub.L2 of the elongate flexible element, either by a second force directed substantially in a direction substantially orthogonal F.sub.T2 to the longitudinal direction of the elongate flexible element 5, or by a second torque M.sub.2, preferably a bending moment, so as to make the stiffness of the elongate flexible element vary according to the prestress level.

[0059] In this embodiment, the first effort is the first longitudinal tensile-compressive force F.sub.L1, and the second effort is the orthogonal second force F.sub.T2, which are variable. Preferably, the two forces lie in the plane of the spiral spring 1. Thus, it is possible to finely adjust the stiffness of the spiral spring 1, in particular to improve the accuracy of running of the movement.

[0060] The prestressing means 6 enable the flexible element 5 to undergo a compressive or tensile effort depending on the value of the forces. Thus, the stiffness of the flexible element 5 is varied.

[0061] Only the flexible element 5 is acted upon to modify its stiffness without acting directly on the strip 2. Thus, more accuracy is obtained because one single element is used to adjust the rigidity. During oscillations, the end 4 of the strip 2 may be movable.

[0062] In addition, the efforts, such as the longitudinal F.sub.L1, F.sub.L2 and orthogonal F.sub.T1, F.sub.T2 forces, are continuously adjustable by the prestressing means 6. In other words, the forces are not restricted to discrete values. Thus, it is possible to adjust the stiffness of the flexible element 5 with a great accuracy.

[0063] The prestressing means 6 include a first lever 8 attached to the outer end 4 of the strip 2. The first lever 8 is curved and surrounds a portion of the coiled strip 2. The first lever 8 has a semi-circular shape, or an arcuate shape with an angle at the centre close to 180?, attached to the appendix 9 of the end 4 of the strip 2.

[0064] The first lever 8 further comprises a first free end 12 which can be actuated by a movement of said first free end 12, in order to apply said efforts. Preferably, the first lever 8 is flexible. The first free end 12 is arranged opposite to the appendix 9. Preferably, the first lever 8 is arranged in the plane of the spiral spring 1. Thus, the first lever 8 allows adjusting the first effort.

[0065] The prestressing means 6 include a second lever 15 attached to the outer end 4 of the strip 2. The second lever 15 is curved and surrounds a portion of the coiled strip 2, preferably on the other side of the strip 2 with respect to the first lever 8. The second lever 15 has a semi-circular shape, or an arcuate shape with an angle at the centre close to 90?, attached to the appendix 9 of the end 4 of the strip 2.

[0066] The second lever 15 further comprises a second free end 16 which can be actuated by a movement of said first free end 16, in order to apply said efforts. The second free end 16 is arranged opposite to the appendix 9.

[0067] Preferably, the second lever 16 is flexible. Preferably, the second lever 15 is arranged in the plane of the spiral spring 1. Thus, the second lever allows adjusting the second effort. Thus, the first 8 and second 15 levers join together and are attached to the same appendix 9 of the curved portion of the end 4 of the strip 2.

[0068] The first lever 8 allows adjusting the first effort, whereas the second lever 15 allows adjusting the second effort. Thus, the two efforts are adjustable independently of one another.

[0069] Preferably, the prestressing means 6 are configured to exert other efforts on the elongate flexible element 5 by means of the first 8 and second levers. Preferably, each lever 8, 15 exerts several efforts, independently of one another, herein three efforts simultaneously.

[0070] The prestressing means 6 are configured to exert a third effort on the elongate flexible element. The third effort being imparted, respectively at the first effort, either by the first tensile/compressive force F.sub.L1, or by the substantially orthogonal first force F.sub.T1, or by the first torque M.sub.1. In this embodiment, the third effort is the substantially orthogonal first force F.sub.T1. The third effort is adjustable thanks to the first lever 8.

[0071] Thus, the first lever 8 allows simultaneously adjusting the first and third efforts.

[0072] The prestressing means 6 are further configured to exert a fourth effort on the elongate flexible element 5, the fourth effort being imparted, respectively at the second effort, either by the second tensile/compressive force F.sub.L1, or by the substantially orthogonal second force F.sub.T2, or by the second torque M.sub.2. In this embodiment, the fourth effort is the substantially longitudinal second force F.sub.L2. The fourth effort is adjustable thanks to the second lever 15.

[0073] The prestressing means 6 are also configured to exert a fifth effort on the elongate flexible element 5, the fifth effort being imparted, respectively at the first effort and at the third effort, either by the first tensile/compressive force F.sub.L1, or by the substantially orthogonal first force F.sub.T1, or by the first torque M.sub.1.

[0074] In this embodiment, the fifth effort is the first torque M.sub.1. The fifth effort is adjustable thanks to the first lever 8. The fifth effort is adjustable by the first lever 8.

[0075] The prestressing means 6 are also configured to exert a sixth effort on the elongate flexible element 5, the sixth effort being imparted, respectively at the second and at the fourth effort, either by the second tensile/compressive force F.sub.L2, or by the substantially orthogonal second force F.sub.T2, or by the second torque M.sub.2. In this embodiment, the sixth effort is the second torque M.sub.2. The second effort is adjustable by the second lever 15.

[0076] In this embodiment, the efforts produced by each lever 8, 15 are opposed, except for the longitudinal forces F.sub.L1, F.sub.L2 which point in the same way. However, the first 8 and second 15 levers have a similar effect on the stiffness of the elongate flexible element 5. The more a lever 8, 15 is raised, the more the stiffness of the elongate flexible element 5 increases.

[0077] Each lever allows modifying the stiffness of the elongate flexible element 5 individually, because it imparts at least two efforts.

[0078] Preferably, the first 8 and second 18 levers are configured to enable an adjustment of the efforts applied thereby at different intensities. Thus, one lever enables an adjustment in a wider setting range, and the other lever enables an adjustment in a finer setting range.

[0079] To obtain a difference in the setting intensity of the stiffness of the elongate flexible element 5 between the two levers 8, 15, the section of the two levers 8, 15 is, for example, selected different, or the stiffness of each lever 8, 15 is selected different.

[0080] Thus, the applied forces or torques are lower with a smaller section or stiffness, than with a larger section or stiffness, so that the two levers 8, 15 allow modifying the stiffness of the elongate flexible element 5 on two different scales.

[0081] Such levers 8, 15 allow keeping a spiral spring 1 with a reduced size, the dimensions being restricted so as to be able to be inserted into a horological movement.

[0082] Indeed, the prestressing means 6 have a shape which matches with the strip 2, so as to keep dimensions that are small enough, because each portion of the prestressing means 6 is close to the strip 2. Hence, the spiral spring 1 is barely modified by the prestressing means. Thus, the spiral spring 1 is compact enough so as to be able to be easily inserted into a movement.

[0083] As shown in FIG. 2, actuating the first lever 8 produces on the end 4 of the strip 2 the longitudinal force F.sub.L1 directed according to the longitudinal axis of the longitudinal flexible element 5, as well as an orthogonal force F.sub.T1 directed according to an orthogonal direction. Actuating the first lever 8 further produces a torque or a bending moment M.sub.1 on the unique blade 5, illustrated by a curved arrow.

[0084] Actuating the second lever 15 produces the longitudinal force F.sub.L2 directed in the same way as the longitudinal force F.sub.L1, the orthogonal force F.sub.T2 directed opposite to the longitudinal force F.sub.T1, and a torque M.sub.2 in the opposite direction as the torque M.sub.1.

[0085] Thus, the stiffness of the unique blade 13, and therefore of the set comprising the strip 2 and the unique flexible blade 13, is modified.

[0086] The longitudinal F.sub.L1, F.sub.L2 and orthogonal F.sub.T1, F.sub.T2 forces as well as the torques M.sub.1, M.sub.2 are varied by the movement of the first free end 12 of the first lever 8 and by the movement of the second free end 16 of the second lever 15. Preferably, the first 12 and the second free end 16 are rigid to facilitate actuation thereof. Thus, the stiffness of the flexible element 5, and therefore of the set comprising the flexible element 5 and the strip 2, is varied.

[0087] The invention also relates to a horological movement comprising such a spiral spring 1. In particular, the spiral spring is used to actuate the movement of a balance.

[0088] 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.

[0089] 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.

[0090] 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.