Spiral spring provided with improved stiffness adjustment means

Abstract

The invention relates to a spiral spring, particularly for a resonator mechanism in watchmaking, the spiral spring (1) comprising a flexible ribbon (2) wound upon itself in several turns, the ribbon (2) having a predefined stiffness, the spiral spring (1) comprising means for adjusting its stiffness, the adjustment means comprising a flexible element (5) arranged in series with the ribbon (2), the flexible element (5) connecting one end (4) of said ribbon (2) to a rigid support (11), so as to add additional stiffness to the ribbon (2), the flexible element (5) preferably having a stiffness greater than that of the ribbon (2), the adjustment means comprising preload means (6) for applying a variable force or torque to the flexible element (5), so as to vary the stiffness of the flexible element (5),The preload means (6) comprise a lever (14) connected to the flexible element (5) and actuable to transmit force or torque to the flexible element (5) by means of an actuator (7), the lever (14) comprising an end (15) movable in a first direction (D1), characterized in that it comprises retaining means (25) arranged to prevent movement of the lever (14) substantially in a second direction (D2). The invention also relates to a resonator mechanism for clocks comprising such a balance spring.

Description

Technical field of the invention

[0001] The invention relates to a spiral spring for a clock resonator mechanism, the spiral spring being provided with improved means for adjusting the stiffness of said spiral spring.

[0002] The invention also relates to a clock resonator mechanism equipped with such a spiral spring. Technological background

[0003] Most modern mechanical watches are equipped with a sprung balance and a Swiss lever escapement mechanism. The sprung balance is the watch's time base. It is also called a resonator.

[0004] The exhaust, meanwhile, fulfills two main functions: maintain the back and forth movements of the resonator; count these back and forth movements.

[0005] To create a mechanical resonator, you need an inertial element, a guide, and an elastic return element. Traditionally, a balance spring acts as an elastic return element for the inertial element, which is a balance wheel. This balance wheel is guided in rotation by pivots that rotate in ruby ​​plain bearings.

[0006] The balance spring generally needs to be adjustable to improve the accuracy of a watch. To this end, means of adjusting the spring's stiffness are used, such as a racket to change the effective length of the spring. Thus, its stiffness is changed to adjust the watch's rate accuracy. However, the effect of a traditional racket to adjust the rate remains limited, and it is not always effective in making the adjustment sufficiently precise, on the order of a few seconds or a few tens of seconds per day.

[0007] Other balance springs have integrated adjustment means. In these balance springs, the rate is not adjusted by changing the effective length of the balance spring, but by applying a force or torque to a flexible element arranged in series with the balance spring. This allows the stiffness of the flexible element to be changed, which partly results in the restoring force acting on the balance, and consequently the stiffness of the balance spring as a whole. Adjusting the stiffness of the balance spring makes it possible to adjust the rate of the regulating organ. Such a balance spring equipped with a flexible element is, for example, described in patent applications EP4009115 and CH0700385 / 2021.

[0008] In these cases, the usual systems cannot be used, as they are not compatible with the balance spring adjustment device. In addition, since the rate is to be adjusted very finely, it is essential that there is no play between the balance spring and its areas of interaction with the index assembly. Indeed, otherwise, there would be a risk of modifying the rate in the event of an impact, if the balance spring does not reposition itself in exactly the same way after the impact.

[0009] To use such a balance spring, a rack system has been described in patent applications EP22177059.7 and CH000678 / 2022. The rack system comprises a stud holder in two parts that can move relative to each other, each part being provided with a stud on which the flexible element is mounted on the one hand, and the prestressing means acting on the flexible element on the other hand. Thus, by moving the two parts relative to each other, the force or torque applied to the flexible element is modified, in order to adjust the stiffness of the balance spring.

[0010] However, in this rack system, the actuation of the adjustment means is tangential to the balance spring, because the moving parts perform a circular movement around the balance spring. This tangential actuation is produced by a rack system that is complex to implement.

[0011] To avoid this problem, it has been devised to actuate the lever of the adjustment device by an actuator performing a substantially rectilinear movement, for example by pulling or pushing the lever, by means of an actuator, directly or by means of an element joining the actuator to the lever. The actuator comprises, for example, a hook engaged with the lever.

[0012] However, the contact area between the actuator and the lever causes friction problems when the lever moves relative to the actuator, particularly when adjusting the reference mark of the regulating member. Indeed, if the balance spring is moved, the lever can be subjected to friction from the actuator and move the hook, so that the rate setting is modified. Summary of the invention

[0013] The aim of the present invention is to overcome all or part of the drawbacks mentioned above by proposing a spiral spring provided with effective and precise adjustment means, configured in particular to avoid disrupting the operation of the regulating organ.

[0014] For this purpose, the invention relates to a spiral spring, in particular for a clock resonator mechanism, the spiral spring comprising a flexible ribbon wound on itself in several turns, the ribbon having a predefined stiffness, the spiral spring comprising means for adjusting its stiffness, the adjustment means comprising a flexible element arranged in series with the ribbon, the flexible element connecting one end of said ribbon to a rigid support, so as to add additional stiffness to the ribbon sequence, the flexible element preferably having a stiffness greater than that of the ribbon, the adjustment means comprising pre-stressing means for applying a variable force or torque to the flexible element, so as to vary the stiffness of the flexible element, the pre-stressing means comprising a lever connected to the flexible element and operable to transmit the force or torque to the flexible element by an actuator,the lever comprising a movable end in a first direction.,

[0015] The invention is remarkable in that the spiral spring comprises retaining means arranged to prevent the lever from moving substantially in a second direction.

[0016] Thanks to the invention, parasitic movements caused by friction between the actuator and the lever are avoided, which risk moving the lever in the second direction and distorting the adjustment. In particular, by choosing the second direction substantially perpendicular to the first direction of movement of the lever, the actuator moves the lever in the first direction, even if the orientation of the spiral spring is modified.

[0017] According to a particular embodiment of the invention, the retaining means connect the rigid support to the lever.

[0018] According to a particular embodiment of the invention, the retaining means comprise a flexible guide.

[0019] According to a particular embodiment of the invention, the flexible guide comprises a first translation table comprising two first flexible blades and a first rigid part.

[0020] According to a particular embodiment of the invention, the flexible guide comprises a second translation table arranged in series with the first translation table, the second translation table comprising two second flexible blades and a second rigid part.

[0021] According to a particular embodiment of the invention, the flexible guide comprises a single flexible blade.

[0022] According to a particular embodiment of the invention, the flexible guide comprises a pair of uncrossed flexible blades.

[0023] According to a particular embodiment of the invention, the retaining means comprise a second flexible lever.

[0024] According to a particular embodiment of the invention, the second direction is substantially perpendicular to the first direction of movement of the lever.

[0025] According to a particular embodiment of the invention, the flexible element comprises a flexible blade.

[0026] According to a particular embodiment of the invention, the torque or force is continuously adjustable by the prestressing means.

[0027] The invention also relates to a rotary resonator mechanism, in particular for a watch movement, comprising an oscillating mass and such a spiral spring. Brief description of the figures

[0028] The aims, advantages and characteristics of the present invention will appear on reading several embodiments given solely as non-limiting examples, with reference to the appended drawings in which: there figure 1 schematically represents a top view of a spiral spring according to a first embodiment of the invention, the figure 2 schematically represents a top view of a spiral spring according to a second embodiment of the invention, the figure 3 schematically represents a top view of a spiral spring according to a third embodiment of the invention, the figure 4 schematically represents a top view of a spiral spring according to a fourth embodiment of the invention, the Figure 5 schematically represents a top view of a spiral spring according to a fifth embodiment of the invention, and the figure 6schematically represents a top view of a spiral spring according to a sixth embodiment of the invention. Detailed description of the invention

[0029] THE figures 1 to 6 each show a schematic representation of a different embodiment of a spiral spring 1, 10, 20, 30, 40, 50, in particular for a regulating organ of a clock resonator mechanism.

[0030] A regulating organ generally comprises an inertial mass, such as an annular balance, a balance shaft, and a balance bridge, not shown in the figures, as well as a spiral spring 1, 10, 20, 30, 40, 50 as an elastic return element of the inertial mass, and configured to make it oscillate.

[0031] In these examples, each spiral spring 1, 10, 20, 30, 40, 50 extends substantially in the same plane.

[0032] The spiral spring 1, 10, 20, 30, 40, 50 comprises a flexible ribbon 2 wound on itself in several turns, the ribbon 2 having a predefined stiffness. The internal end 9 of the ribbon 2 comes from the same material or is assembled to a support 3, generally called a collet. The support 3 has a substantially triangular shape, so that it can be threaded around the balance shaft.

[0033] The spiral spring 1, 10, 20, 30, 40, 50 further comprises means for adjusting its stiffness. For example, the adjustment means can be actuated by a user when the regulating member is mounted on the plate of the watch movement.

[0034] The adjustment means comprise a flexible element 5 arranged in series with the ribbon 2, the flexible element 5 connecting an external end 4 of said ribbon 2 to a rigid support 11 intended to be fixed relative to the flexible element 5. The flexible element 5 is integral with the external end 4 of the ribbon 2. The flexible element 5 is a different element from the wound ribbon 2.

[0035] The flexible element 5 adds additional stiffness to that of the strip 2. The flexible element 5 preferably has a stiffness greater than that of the strip 2. The flexible element 5 is here arranged in the extension of the strip 2. Preferably, the adjustment means and the strip 2 are in one piece, or even formed from the same material, for example silicon.

[0036] The flexible element 5 of the spiral spring 1, 10, 20, 30, 40, 50 comprises a first flexible blade 19 and a movable rigid part 18, which extends from the external end of the ribbon 2, and is connected to the first flexible blade 19, preferably on the same side of the rigid part 18. The first flexible blade 19 is connected on the other hand to the rigid support 11.

[0037] The spiral spring adjustment means 1, 10, 20, 30, 40, 50 further comprise pre-stressing means 6 for applying a variable force or torque to the flexible element 5. Thus, the stiffness of the spiral spring can be adjusted. The torque or force is continuously adjustable by the pre-stressing means 6. In other words, the torque or force is not restricted to point values. Thus, the stiffness of the flexible element 5 can be adjusted with great precision.

[0038] The prestressing means 6 comprise a secondary flexible blade and a curved semi-rigid part 21, arranged on an opposite side of the rigid part 18 in the extension of the first flexible blade 19.

[0039] The secondary flexible blade and the curved semi-rigid element 21 are connected by the other end to a curved lever 14 bypassing the ribbon 2. The secondary flexible blade and the curved semi-rigid element are connected to a rigid structure 17, 27, 37 linked to the rigid support 11.

[0040] The force or torque is exerted on the free end 15 of the lever 14. Thus, the lever 14 of the prestressing means 6 transmits the force or torque to the flexible element 5 via the secondary flexible blade 19 so as to modify the stiffness of the spiral spring 1, 10, 20, 30, 40, 50.

[0041] To actuate the lever 14 and adjust the speed, the regulating member further comprises an actuating system comprising an actuator 7 in contact with the lever 14. The actuator is configured to push and / or pull on the lever 14.

[0042] In the figures, the actuator 7 is represented by a circular body in contact with the lever 14 on the inner side towards the strip 2. Preferably, the actuator 7 comprises a hook at least partly surrounding the lever 14, preferably at a rigid part 23 arranged at the end 15 of the lever 14.

[0043] According to the invention, the spiral spring 1, 10, 20, 30, 40, 50 comprises retaining means 25 for retaining the lever 14 in a second direction D2. The second direction D2 is substantially perpendicular to the movement in a first direction D1 of the end 15 of the lever 14 and of the actuator 7. Thus, the lever is prevented from moving in this second direction D2, to prevent the adjustment of the step from being distorted by such a movement when it is desired to adjust it by means of the actuator.

[0044] Indeed, if the spiral spring 1, 10, 20, 30, 40, 50 and the actuator 7 move relative to each other, the friction of the contact between them can cause a lateral movement of the lever 14, which causes a precision error in the adjustment of the step.

[0045] Thanks to the retaining means 25, in the event of displacement relative to each other, the retaining means 25 prevent lateral displacement of the lever 14 due to friction.

[0046] Furthermore, when the actuator 7 pulls or pushes the end 15 of the lever 14, the latter moves only in the first direction D1 of movement of the actuator 7, so that it substantially keeps its position laterally relative to the strip 2.

[0047] Preferably, these retaining means 25 comprise a flexible guide arranged between the lever and the rigid support 11 of the flexible element 5. Here between the lever and the rigid support 17.

[0048] In the first embodiment of the figure 1 , the flexible guide is a translation table.

[0049] The rigid support 11 has an L shape, a first branch 46 of the L serving as a connection with the first flexible blade 19, the second branch 47 of the L being oriented on the side opposite the first flexible blade 19 so that it can be assembled to the clockwork movement 10.

[0050] The rigid support 17 further comprises an arm 8 extending here parallel to the second branch 47 of the L, towards the end 15 of the lever 14.

[0051] The translation table is provided with two flexible blades 22, 24, substantially parallel, and a rigid part 23 movable relative to the arm 8, and on which the two flexible blades 21, 22 are mounted. The two flexible blades 22, 24 are connected to the arm 8 of the rigid support 17.

[0052] The rigid part 23 is assembled directly to the end of the lever 14.

[0053] Thanks to the translation table, the lever can move mainly in the first direction D1 substantially perpendicular to the flexible blades 22, 24 of the translation table, but not in the second direction D2 which is substantially parallel to the flexible blades in the rest position of the translation table. Indeed, the flexible blades 22, 24 retain the lever 14 in this second direction D2, but they allow the lever to move in the first direction D1.

[0054] The flexible element 5, the prestressing means 6 and the retaining means 25 form a closed circuit around the wound ribbon.

[0055] In the second embodiment of the figure 2 , the retaining means 25 comprise a second translation table arranged in series with the first translation table.

[0056] Here, the rigid support 17 of the flexible element 5 does not include an arm.

[0057] The first translation table is mounted at the end 15 of the lever 14, as in the first embodiment.

[0058] The second translation table extends directly from the rigid support 11 of the flexible element 5. The second translation table comprises substantially parallel second flexible blades 25, 26 extending from the rigid support 11, as well as a second rigid part 29 movable relative to the rigid support 17, to which the second flexible blades 25, 26 are assembled.

[0059] The first flexible blades 22, 24 are mounted on the second rigid part 29.

[0060] A second translation table makes it possible to increase the distance traveled by the lever 14 in the first direction D1, while maintaining a substantially rectilinear line of movement.

[0061] There figure 3 shows a third embodiment of spiral spring 20 of the figure 3, wherein the flexible guide comprises a single flexible blade 32 connecting the elastic element 5 to a rigid part 23 at the end 15 of the lever 14 via a half-moon shaped body 31.

[0062] The half-moon shaped body 31 is connected to the flexible element 5 on the one hand, and to the single flexible blade 32 on the other hand. Here, the flexible blade is straight in the rest position of the single flexible blade 32.

[0063] The single flexible blade 32 makes it possible to retain the lever 14 to prevent it from moving in a second direction D2 perpendicular to the first direction D1 of movement of the actuator 7.

[0064] Alternatively, as shown in the variant embodiment of the figure 4, the flexible guide comprises a curved flexible blade 33. In this case, the rigid structure has an S-shape without a branch, half-moon-shaped body or rear arm. The curved blade 33 is mounted directly on the rigid S-shaped structure, and directly connects the rigid part 23 to the end 15 of the lever 14.

[0065] On the Figure 5 , the flexible guide of the fourth embodiment comprises a flexible pivot with two uncrossed flexible blades 34, 35.

[0066] The rigid structure 27 has an S shape with a rounded arm 38 extending rearwardly. The two flexible blades 34, 35 are uncrossed from the end of the rounded arm 38 to the rigid portion 23 at the end 15 of the lever 14.

[0067] The uncrossed blades 34, 35 have substantially the same effect as the blades of the translation table.

[0068] In the embodiment of the figure 6, the retaining means 25 comprise a second flexible lever 36 arranged by symmetry of the first lever 14 around the flexible strip 2. The first lever 14 and the second lever 36 are joined to each other at a rigid junction 37 and form a ring part around the strip 2.

[0069] The actuator 7 is engaged with the rigid junction 37 of the two levers 14, 36. The rigid junction 37 is U-shaped to allow the actuator 7 to fit inside the U.

[0070] The second lever 36 prevents the first lever from shifting in the second direction D2 and allows it to remain movable in the first direction D1 only.

[0071] The invention also relates to a regulating organ and a rotary resonator mechanism, in particular for a watch movement. The regulating organ of the resonator mechanism comprises an oscillating mass, not shown in the figures, and a balance spring 1, 10, 20, 30, 40, 50 as described previously. The oscillating mass is for example an annular balance. The oscillating mass is joined to the balance spring to be secured to the support 3.

Claims

1. Spiral spring, in particular for a clock resonator mechanism, the spiral spring (1, 10, 20, 30, 40, 50) comprising a flexible ribbon (2) wound on itself in several turns, the ribbon (2) having a predefined stiffness, the spiral spring (1, 10, 20, 30, 40, 50) comprising means for adjusting its stiffness, the adjustment means comprising a flexible element (5) arranged in series with the ribbon (2), the flexible element (5) connecting one end (4, 9) of said ribbon (2) to a rigid support (11, 14, 17, 24), so as to add additional stiffness after the ribbon (2), the flexible element (5) preferably having a stiffness greater than that of the ribbon (2), the adjustment means comprising prestressing means (6) for applying a variable force or torque to the flexible element (5), so as to vary the stiffness of the flexible element (5),the prestressing means (6) comprising a lever (14) connected to the flexible element (5) and operable to transmit the force or torque to the flexible element (5) by an actuator (7), the lever (14) comprising an end (15) movable in a first direction (D1), , characterized in that it comprises retaining means (25) arranged to prevent the movement of the lever (14) substantially in a second direction (D2).

2. Spiral spring according to claim 1, characterized in that the retaining means (25) connect the rigid support (11, 14, 17, 24) to the lever (14).

3. Spiral spring according to claim 1 or 2, characterized in that the retaining means (25) comprise a flexible guide.

4. Spiral spring according to claim 3, characterized in that the flexible guide comprises a first translation table comprising two first flexible blades (22, 24) and a first rigid part (23).

5. Spiral spring according to claim 4, characterized in that the flexible guide comprises a second translation table arranged in series with the first translation table, the second translation table comprising two second flexible blades (26, 28) and a second rigid part (29).

6. Spiral spring according to claim 3, characterized in that the flexible guide comprises a single flexible blade (32, 33).

7. Spiral spring according to claim 3, characterized in that the flexible guide comprises a pair of uncrossed flexible blades (34, 35).

8. Spiral spring according to claim 2, characterized in that the retaining means (25) comprise a second flexible lever (36).

9. Spiral spring according to any one of the preceding claims, characterized in that the second direction (D2) is substantially perpendicular to the first direction (D1) of movement of the lever (14).

10. Spiral spring according to any one of the preceding claims, characterized in thatthe flexible element (5) comprises a flexible blade (19).

11. Spiral spring according to any one of the preceding claims, characterized in that the torque or force is continuously adjustable by the prestressing means (6).

12. Rotary resonator mechanism, in particular for a watch movement, comprising an oscillating mass, characterized in that it comprises a spiral spring (1, 10, 20, 30, 40, 50) according to any one of the preceding claims.

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