Coil spring with improved stiffness adjustment

Abstract

The invention relates to a coil spring, in particular for a watch resonator mechanism and a watch resonator mechanism comprising the coil spring. The coil spring comprises a flexible strip coiled on itself by multiple turns, the flexible strip having a predetermined stiffness and comprising an adjustment means for adjusting the stiffness thereof, the adjustment means comprising a flexible element arranged in series with the flexible strip, the flexible element connecting one end of the flexible strip to a rigid support in order to add additional stiffness to the flexible strip, and the flexible element connecting the other end of the flexible strip to the rigid support. The stiffness of the flexible element is preferably greater than the stiffness of the flexible strip, the adjustment device comprising a prestressing means for applying a variable force or torque to the flexible element in order to vary the stiffness of the flexible element, the prestressing means comprising a lever connected to the flexible element and actuatable by an actuator to transmit the force or torque to the flexible element, the lever comprises an end movable in a first direction, characterised in that the coil spring comprises retaining means arranged to prevent movement of the lever substantially in a second direction.

Description

Technical Field

[0001] The present invention relates to a helical spring for a watch resonator mechanism, provided with an improved adjustment device for adjusting the stiffness of said helical spring.

[0002] The invention also relates to a watch resonator mechanism equipped with such a helical spring. Background Art

[0003] Most of the current mechanical watches are equipped with a balance wheel-ballast mechanism and a Swiss lever escapement. The balance wheel-ballast mechanism is the time base of the watch. It is also called a resonator.

[0004] As for the escapement, it has two main functions:

[0005] - Keep the resonator in reciprocating motion;

[0006] - These reciprocating movements are counted.

[0007] A mechanical resonator requires an inertial element, a guide element and an elastic return element. Traditionally, a spiral spring is used as the elastic return element for the inertial element formed by a balance wheel. This balance wheel is guided in rotation by a pivot turning in a ruby ​​plain bearing.

[0008] The coil spring usually needs to be adjustable to improve the accuracy of the watch. For this purpose, a device for adjusting the stiffness of the coil spring is used, such as a speed needle assembly for changing the effective length of the coil spring. Therefore, its stiffness can be changed to adjust the accuracy of the travel error of the watch. However, the role of the traditional speed needle assembly for adjusting the travel error is still limited, and it is not always effective for achieving sufficiently accurate adjustment of the order of a few seconds or tens of seconds per day.

[0009] Other spiral springs include integrated adjustment devices. In these spiral springs, the travel time difference is not adjusted by changing the effective length of the spiral spring, but by applying a force or torque to a flexible element arranged in series with the spiral spring. This makes it possible to change the stiffness of the flexible element, which partly determines the restoring force acting on the balance wheel and thus the stiffness of the entire spiral spring. By adjusting the stiffness of the spiral spring, the travel time difference of the speed regulating member can be adjusted. Such spiral springs with flexible elements are described in patent applications EP4009115 and CH0700385 / 2021.

[0010] In these cases, the usual systems cannot be used, as they are not compatible with the coil spring adjustment. In addition, since the adjustment of the rate must be very fine, there must be no play between the coil spring and the area where it interacts with the regulator mechanism. Otherwise, in the event of an impact, there is a risk of changing the rate if the coil spring does not reposition itself in exactly the same way after the impact.

[0011] In order to use this coil spring, patent applications EP22177059.7 and CH000678 / 2022 describe a speed needle assembly system. The rack system includes an external post holder divided into two parts that can move relative to each other, each part is equipped with an external post, on the one hand, a flexible element is mounted on the external post, and on the other hand, a prestressing device acts on the flexible element. In this way, by moving the two parts relative to each other, the force or torque applied to the flexible element can be changed to adjust the stiffness of the coil spring.

[0012] However, in this speed needle assembly system, when the moving part performs a circular motion around the spiral spring, the adjusting device is actuated in the tangential direction of the spiral spring. This tangential actuation is produced by the speed needle assembly system which is complicated to implement.

[0013] To avoid this problem, designs have been devised to actuate the lever of the adjustment device by means of an actuator performing a substantially linear movement, for example by pulling or pushing the lever by means of the actuator directly or via an element engaging the actuator to the lever. The actuator comprises for example a hook engaging with the lever.

[0014] However, when the lever moves relative to the actuator, and especially when the reference mark on the speed regulating member is adjusted, the contact area between the actuator and the lever causes friction problems. In fact, if the spiral spring moves, the lever may be rubbed by the actuator and move the hook, thus changing the travel time setting. Summary of the invention

[0015] The object of the present invention is to overcome some or all of the above-mentioned drawbacks by providing a helical spring equipped with effective and precise adjustment means, which are particularly configured to avoid interfering with the operation of the speed regulating member.

[0016] To this end, the invention relates to a helical spring, in particular for a watch resonator mechanism, comprising a flexible strip coiled a plurality of times on itself, the flexible strip having a predetermined stiffness, the helical spring comprising adjustment means for adjusting its stiffness, the adjustment means comprising a flexible element arranged in series with the flexible strip, the flexible element connecting one end of the flexible strip to a rigid support so as to add additional stiffness to the flexible strip, the stiffness of the flexible element preferably being greater than the stiffness of the flexible strip, the adjustment means comprising prestressing means for applying a variable force or torque to the flexible element so as to vary the stiffness of the flexible element, the prestressing means comprising a rod connected to the flexible element and actuable by an actuator to transmit the force or torque to the flexible element, the rod comprising an end movable in a first direction.

[0017] The invention is characterized in that the helical spring comprises retaining means arranged to prevent the lever from moving substantially in the second direction.

[0018] The present invention avoids parasitic motion caused by friction between the actuator and the rod, which may cause the rod to move in a second direction and distort the adjustment. Specifically, by selecting the second direction to be substantially perpendicular to the first direction of movement of the rod, the actuator causes the rod to move in the first direction even if the orientation of the coil spring changes.

[0019] In a particular embodiment of the invention, said retaining means connects said rigid support to said rod.

[0020] In a particular embodiment of the present invention, the retaining device comprises a flexible guiding element.

[0021] In a specific embodiment of the present invention, the flexible guiding element comprises a first translation stage, wherein the first translation stage comprises a first rigid portion and two first flexible sheet-like members.

[0022] In a specific embodiment of the present invention, the flexible guiding element comprises a second translation stage arranged in series with the first translation stage, the second translation stage comprising a second rigid part and two second flexible sheet-like members.

[0023] In a particular embodiment of the present invention, the flexible guiding element comprises a single flexible sheet.

[0024] In a specific embodiment of the present invention, the flexible guiding element comprises a pair of non-intersecting flexible sheet members.

[0025] In a specific embodiment of the present invention, the retaining device comprises a second flexible rod.

[0026] According to a specific embodiment of the present invention, the second direction is substantially perpendicular to the first movement direction of the rod.

[0027] In a specific embodiment of the present invention, the flexible element comprises a flexible sheet.

[0028] In a specific embodiment of the present invention, the force or moment can be continuously adjusted by the prestressing device.

[0029] The invention also relates to a rotating resonator mechanism, in particular for a watch movement, comprising an oscillating mass and a helical spring as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The objects, advantages and features of the present invention will become apparent from a number of embodiments thereof given by way of non-limiting example only with reference to the accompanying drawings, in which:

[0031] - Figure 1 Schematically shows a top view of a coil spring according to a first embodiment of the present invention,

[0032] - Figure 2 Schematically shows a top view of a coil spring according to a second embodiment of the present invention,

[0033] - Figure 3 Schematically shows a top view of a coil spring according to a third embodiment of the present invention,

[0034] - Figure 4 Schematically shows a top view of a coil spring according to a fourth embodiment of the present invention,

[0035] - Figure 5 Schematically shows a top view of a coil spring according to a fifth embodiment of the present invention, and

[0036] - Figure 6 A top view of a coil spring according to a sixth embodiment of the present invention is schematically shown. DETAILED DESCRIPTION

[0037] Figures 1 to 6 Schematic diagrams of helical springs 1 , 10 , 20 , 30 , 40 , 50 , respectively, of different embodiments, in particular for a regulating member of a watch resonator mechanism, are shown.

[0038] The speed regulating member generally comprises an inertial mass body (such as an annular balance wheel), a balance shaft and a balance cock (not shown in the figure), and comprises a coil spring 1, 10, 20, 30, 40, 50 as an elastic reset element of the inertial mass body and configured to make it oscillate.

[0039] In these examples, each coil spring 1 , 10 , 20 , 30 , 40 , 50 extends substantially in the same plane.

[0040] The helical spring 1, 10, 20, 30, 40, 50 comprises a flexible strip 2 which is coiled a number of times on itself and has a predetermined stiffness. The inner end 9 of the flexible strip 2 is integral with or assembled to a support 3, which is usually called a collet. The support 3 is generally triangular so that it can slide around the balance shaft.

[0041] The helical spring 1, 10, 20, 30, 40, 50 also comprises an adjustment device for adjusting its stiffness. The adjustment device can be actuated in particular by a user, for example when the regulating member is mounted on a plate of a watch movement.

[0042] The regulating device comprises a flexible element 5 arranged in series with the flexible strip 2, connecting the outer end 4 of said flexible strip 2 to a rigid support 11 intended to be fixed relative to the flexible element 5. The flexible element 5 is fixed to the outer end 4 of the flexible strip 2. The flexible element 5 is an element distinct from the flexible strip 2 which is coiled.

[0043] The flexible element 5 adds additional rigidity to the flexible strip 2. The flexible element 5 preferably has a higher rigidity than the flexible strip 2. In this case, the flexible element 5 is arranged in the continuation of the flexible strip 2. Preferably, the adjustment device and the flexible strip 2 are made in one piece, or even made of the same material, such as silicon.

[0044] The flexible element 5 of the helical spring 1, 10, 20, 30, 40, 50 comprises a first flexible sheet 19 and a movable rigid portion 18 extending from the outer end of the flexible strip 2 and connected to the first flexible sheet 19, preferably on the same side as the rigid portion 18. The first flexible sheet 19 is also connected to the rigid support 11.

[0045] The adjustment device of the helical spring 1, 10, 20, 30, 40, 50 further comprises a prestressing device 6 for applying a variable force or moment to the flexible element 5. In this way, the stiffness of the helical spring can be adjusted. The force or moment can be adjusted continuously by the prestressing device 6. In other words, the force or moment is not limited to a point value. In this way, the stiffness of the flexible element 5 can be adjusted very accurately.

[0046] The prestressing device 6 comprises a less flexible sheet and a curved semi-rigid portion 21 which are arranged in the extension of the first flexible sheet 19 and on the opposite side of the rigid portion 18 .

[0047] The less flexible sheet and the curved semi-rigid portion 21 are connected at the other end to a curved rod 14 extending around the flexible strip 2. The less flexible sheet and the curved semi-rigid portion are connected to a rigid structure 17, 27, 37 joined to a rigid support 11.

[0048] The force or moment is exerted on the free end 15 of the rod 14. The rod 14 of the prestressing device 6 thus transmits the force or moment to the flexible element 5 via the less flexible sheet, in order to change the stiffness of the helical spring 1,10,20,30,40,50.

[0049] In order to actuate the lever 14 and adjust the running time difference, the speed regulating member also comprises an actuation system comprising an actuator 7 in contact with the lever 14. The actuator is configured to push and / or pull the lever 14.

[0050] In the figures, the actuator 7 is represented by a circular body which contacts the rod 14 on the inside, towards the flexible strip 2. Preferably, the actuator 7 comprises a hook which at least partially surrounds the rod 14, preferably at a rigid portion 23 arranged at its end 15.

[0051] According to the invention, the helical spring 1, 10, 20, 30, 40, 50 comprises a retaining device 25 for retaining the rod 14 in a second direction D2. The second direction D2 is substantially perpendicular to the movement of the end 15 of the rod 14 and of the actuator 7 in the first direction D1. In this way, the rod is prevented from moving in this second direction D2, so that when an adjustment is to be made with the aid of the actuator, the adjustment of the travel time difference is not distorted by such a movement.

[0052] Indeed, if the helical springs 1 , 10 , 20 , 30 , 40 , 50 and the actuator 7 move relative to one another, the contact friction between them can cause the rod 14 to move sideways, thus resulting in precision errors in the time difference adjustment.

[0053] Due to the presence of the retaining means 25 , in the event of a relative movement of the rod 14 to each other, the retaining means 25 prevents the rod 14 from moving sideways due to friction.

[0054] Furthermore, when the actuator 7 pulls or pushes the end 15 of the rod 14 , the rod 14 only moves in the first direction D1 of the actuator 7 , so that it substantially maintains its position laterally relative to the flexible strip 2 .

[0055] Preferably, these retaining means 25 comprise flexible guiding elements arranged between the rod and the rigid support 11 of the flexible element 5 , here between the rod and the rigid support 17 .

[0056] exist Figure 1 In a first embodiment of the invention, the flexible guiding element is a translation stage.

[0057] The rigid support 11 is L-shaped, with a first leg 46 of the L serving as a connection to the first flexible sheet 19 and a second leg 47 of the L facing away from the first flexible sheet 19 so that it can be assembled to the watch movement 10 .

[0058] The rigid support 17 also comprises an arm 8 which, in this example, extends parallel to the second leg 47 of the L towards the end 15 of the rod 14 .

[0059] The translation stage is equipped with two substantially parallel flexible sheets 22, 24, and a rigid portion 23 movable relative to the arm 8, on which the two flexible sheets 22, 24 are mounted. The two flexible sheets 22, 24 are connected to the arm 8 of the rigid support 17.

[0060] The rigid portion 23 is assembled directly at the end of the rod 14 .

[0061] Due to the presence of the translation stage, the rod can mainly move in a first direction D1, which is substantially perpendicular to the flexible sheets 22, 24 of the translation stage, but cannot move in a second direction D2, which is substantially parallel to the flexible sheets 22, 24 in the rest position of the translation stage. In fact, the flexible sheets 22, 24 hold the rod 14 in this second direction D2, but they allow the rod to move in the first direction D1.

[0062] The flexible element 5, the prestressing means 6 and the retaining means 25 form a closed loop around the coiled strip.

[0063] exist Figure 2 In a second embodiment, the holding device 25 comprises a second translation stage arranged in series with the first translation stage.

[0064] Here, the rigid support 17 of the flexible element 5 does not comprise an arm.

[0065] The first translation stage is mounted at the end 15 of the rod 14, as in the first embodiment.

[0066] The second translation stage extends directly from the rigid support 11 of the flexible element 5. The second translation stage comprises substantially parallel second flexible sheets 25, 26 extending from the rigid support 11 and a second rigid portion 29 movable relative to the rigid support 17 to which the second flexible sheets 25, 26 are connected.

[0067] The first flexible sheet elements 22 , 24 are mounted on the second rigid portion 29 .

[0068] The second translation stage allows increasing the distance covered by the rod 14 in the first direction D1 while maintaining a substantially rectilinear movement.

[0069] Figure 3 A third embodiment of a helical spring 20 is shown, in which the flexible guiding element comprises a single flexible blade 32 which connects the flexible element 5 to the rigid portion 23 at the end 15 of the rod 14 via a half-moon-shaped body 31 .

[0070] The half-moon-shaped body 31 is connected on the one hand to the flexible element 5 and on the other hand to a single flexible sheet 32. Here, the flexible sheet in the rest position of the single flexible sheet 32 ​​is straight.

[0071] The single flexible leaf 32 allows the rod 14 to be retained so as to prevent it from moving in a second direction D2 perpendicular to the first direction D1 of the actuator 7 .

[0072] Alternatively, if Figure 4 In the variant shown, the flexible guiding element comprises a curved flexible sheet 33. In this case, the rigid structure is S-shaped, without legs, with a half-moon-shaped body or rear arm. The curved flexible sheet 33 is mounted directly on the S-shaped rigid structure and connects the rigid part 23 directly to the end 15 of the rod 14.

[0073] exist Figure 5 In the embodiment, the flexible guiding element comprises a flexible pivot having two non-intersecting flexible flaps 34, 35.

[0074] The rigid structure 27 is S-shaped with a circular arm 38 extending backwards. The two flexible flaps 34, 35 do not cross from the tip of the circular arm 38 to the rigid portion 23 at the end 15 of the rod 14.

[0075] The non-intersecting blades 34, 35 have substantially the same effect as the blades of the translation stage.

[0076] exist Figure 6 In the embodiment of the present invention, the retaining device 25 comprises a second flexible rod 36 arranged symmetrically with the first rod 14 around the flexible strip 2. The first rod 14 and the second rod 36 are joined together at a rigid joint 37 and form part of a loop around the flexible strip 2.

[0077] The actuator 7 engages with the rigid engagement portion 37 of the two rods 14, 36. The rigid engagement portion 37 is U-shaped so that the actuator 7 can be inserted inside the U-shape.

[0078] The second lever 36 prevents the first lever from moving in the second direction D2 and allows it to keep moving only in the first direction D1 .

[0079] The invention also relates to a speed regulating member and a rotating resonator mechanism, in particular for a watch movement. The speed regulating member of the resonator mechanism comprises an oscillating mass, not shown in the figures, and a helical spring 1, 10, 20, 30, 40, 50 as described above. The oscillating mass is, for example, an annular balance. The oscillating mass is combined with a helical spring so as to be fixed to a support 3.

Claims

1. A helical spring, in particular for a watch resonator mechanism, the helical spring (1, 10, 20, 30, 40, 50) comprising a flexible strip (2) wound a plurality of times on itself, the flexible strip (2) having a predetermined stiffness, the helical spring (1, 10, 20, 30, 40, 50) comprising an adjustment device for adjusting its stiffness, the adjustment device comprising a flexible element (5) arranged in series with the flexible strip (2), the flexible element (5) connecting one end (4, 9) of the flexible strip (2) to a rigid support (11, 14, 17, 24) in order to increase the stiffness of the flexible strip (2) The present invention relates to a method for adjusting the flexible element (5) to provide an additional stiffness, the stiffness of the flexible element (5) being preferably greater than the stiffness of the flexible strip (2), the adjusting device comprising a prestressing device (6) for applying a variable force or torque to the flexible element (5) in order to change the stiffness of the flexible element (5), the prestressing device (6) comprising a rod (14) connected to the flexible element (5) and actuable by an actuator (7) to transmit the force or torque to the flexible element (5), the rod (14) comprising an end (15) movable in a first direction (D1), characterized in that The helical spring comprises a retaining device (25) arranged to prevent the lever (14) from moving substantially in a second direction (D2).

2. The coil spring according to claim 1, characterized in that The retaining device (25) connects the rigid support (11, 14, 17, 24) to the rod (14).

3. The coil spring according to claim 1 or 2, characterized in that: The retaining device (25) comprises a flexible guiding element.

4. The coil spring according to claim 3, characterized in that The flexible guiding element comprises a first translation stage comprising a first rigid portion (23) and two first flexible sheets (22, 24).

5. The coil spring according to claim 4, characterized in that The flexible guiding element comprises a second translation stage arranged in series with the first translation stage, the second translation stage comprising a second rigid portion (29) and two second flexible sheet-like elements (26, 28).

6. The coil spring according to claim 3, characterized in that The flexible guiding element comprises a single flexible sheet (32, 33).

7. The coil spring according to claim 3, characterized in that The flexible guiding element comprises a pair of non-intersecting flexible sheet members (34, 35).

8. The coil spring according to claim 2, characterized in that The retaining device (25) comprises a second flexible rod (36).

9. A helical spring according to any one of the preceding claims, characterised in that The second direction (D2) is substantially perpendicular to the first direction (D1) of movement of the rod (14).

10. A helical spring according to any one of the preceding claims, characterised in that The flexible element (5) comprises a flexible sheet (19).

11. A helical spring according to any one of the preceding claims, characterised in that The force or moment can be continuously adjusted by means of the prestressing device (6).

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

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