Hairsprings, rotating resonators, and watch movements

Abstract

To provide a balance spring, in particular for use in a horological resonator.SOLUTION: A balance spring 1 includes a flexible strip 2 coiled on itself into several coils, the strip having predefined flexibility. The balance spring includes means for adjusting its flexibility. The adjustment means includes an elastic element 5 in direct contact with the strip. The elastic element preferably has flexibility less than that of the strip. The adjustment means includes prestressing means 6 to apply a variable force or torque to the elastic element so as to vary the flexibility of the elastic element. The elastic element and the strip are separate and assembled together by assembly means. A horological resonator including such a balance spring is also disclosed.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a hairspring for a timepiece resonator, the hairspring being provided with means for adjusting its flexibility, and also to a timepiece resonator equipped with such a hairspring. [Background technology]

[0002] Most modern mechanical portable watches have a spring balance and a Swiss pallet escapement. The spring balance forms the time base of the watch. It is also called the resonator or regulator.

[0003] Secondly, the escapement serves two main functions. · Maintaining the reciprocating motion of the resonator. · Count these back and forth movements.

[0004] To create a mechanical resonator, an inertia element, a guide and an elastic return element are required. Conventionally, a balance spring serves as the elastic return element for the inertia element formed by the balance, which is rotatably guided by a shaft that rotates in a ruby ​​plain bearing.

[0005] Generally, to improve the accuracy of a watch, it is necessary to be able to adjust the spring balance. For this purpose, a means is used to adjust the flexibility of the balance spring, such as a regulator to change the effective length of the balance spring. The flexibility is therefore changed to adjust the operation accuracy of the watch. However, the effect of the regulator that adjusts the operation of the conventional operation is limited, and it is not necessarily effective for high-precision adjustment of a few seconds or tens of seconds per day.

[0006] To adjust the movement more finely, there are adjustment means comprising one or more screws located after the balance, by acting on which the inertia of the balance is modified and, therefore, its movement.

[0007] However, this adjustment method is not easy to implement and still does not allow for a sufficiently fine adjustment of the oscillator's operating settings.

[0008] To increase the accuracy of the adjustment, a previous application (EP 22177059.7) proposed adding means for adjusting the flexibility of the balance spring, comprising an elastic element arranged in series with a coiled flexible strip, which is subjected to a variable prestress so as to modify its flexibility, thereby allowing the operation of the governor to be adjusted.

[0009] By acting on the prestressing means, the force or torque applied to the elastic element is modified, which results in a change in the flexibility of the assembly including the elastic element and the strip. In fact, the elastic element arranged in series with the strip combines with the flexibility of the strip to add an additional flexibility to the strip. Thus, when the prestressing means applies a variable force or torque to the elastic element, it modifies the flexibility of the elastic element and thus the flexibility of the assembly including the strip, without changing the flexibility of the strip, whose ends retain substantially the same position, regardless of the variable force or torque applied to the elastic element.

[0010] This balance spring is in particular provided in one piece and made from the same material, for example silicon, to facilitate its manufacture.

[0011] As regards the assembly of an integral hairspring in a movement, it is generally the case that a certain part of the hairspring is glued to a plate or a plate cock, in particular to one or more hairspring studs. In particular, the elastic element needs to be connected to the plate via a fixed support, so that a prestress can be created in the elastic element.

[0012] In the long term, however, such prestressing tends to induce distortion of the adhesive connecting the fixed support to the balance spring stud, which may result in maladjustment of the adjusting means and even detachment of the fixed support from the balance spring stud.

[0013] Other assembly methods, such as hammering or screwing, cannot be used with certain materials, such as silicon, which is a more fragile and therefore brittle material, and in fact the stresses induced in the material by hammering or screwing can weaken or even directly break elastic elements using such materials. Summary of the Invention [Problem to be solved by the invention]

[0014] The present invention aims to overcome all or part of the aforementioned drawbacks by providing a hairspring equipped with effective and accurate adjustment means and adapted in particular to be assembled over a long period of time on the plate of a timepiece movement. [Means for solving the problem]

[0015] To this end, the invention relates to a hairspring for use in a timepiece resonator, the hairspring comprising a flexible strip wound itself into several coils, the strip having a given flexibility, the hairspring comprising means for adjusting its flexibility, the adjusting means comprising an elastic element arranged in series with the strip, which connects one end of the strip to a fixed support and adds additional flexibility to the strip, the elastic element preferably having a flexibility less than that of the strip, and the adjusting means comprising prestressing means for applying a variable force or torque to the elastic element, preferably varying only the flexibility of the elastic element without substantially modifying the position of the end of the strip.

[0016] The present invention is notable in that the elastic element and the strip are separate and assembled together by an assembly means.

[0017] According to the invention it is possible to manufacture the strip and the elastic element independently of each other and connect them by an assembly means. It is therefore possible to choose different materials for the flexible strip and the elastic element. For example, a first material can be chosen for the elastic element which is stronger, allowing the use of an assembly means which is more durable than an adhesive.

[0018] It is therefore possible to assemble the elastic element to the balance spring stud using assembly methods such as hammering or screwing without risking damage or breakage, and furthermore the use of adhesives which would create a less durable assembly is avoided.

[0019] On the other hand, less durable materials such as silicon or silicon oxide can be used for the hairspring strips, which materials have other advantageous properties, in particular non-magnetic properties.

[0020] In this case, the flexible strip and the elastic element can be assembled using adhesive, since the assembly joint between the strip and the elastic element is not exposed to prestressing means.

[0021] According to a particular embodiment of the invention, the elastic element is formed from a first material supporting assembly means, such as hammering or screwing, which generate stresses induced in the first material.

[0022] According to a particular embodiment of the invention, the prestressing means is formed from a first material.

[0023] According to a particular embodiment of the invention, the first material is selected from metals or metal alloys such as nickel silver, CuBe2, steel or nickel-based alloys (Ni, NiP, NiW), or Ni-based alloys, CuNiSn-based alloys, or materials for the LIGA process such as maraging steel.

[0024] According to a particular embodiment of the invention, the strip is formed from a second material different from the first material, for example a material comprising silicon or silicon oxide, preferably entirely.

[0025] According to a particular embodiment of the invention, the second material is such as Nivarox CT® or such as Nivachron®.

[0026] According to a particular embodiment of the invention, the strip and the elastic element are assembled by gluing as an assembly means.

[0027] According to a particular embodiment of the invention, the elastic elements are arranged at the outer ends of the strips.

[0028] According to a particular embodiment of the invention, the elastic element comprises a flexible guide with at least one flexible blade, preferably two non-intersecting blades, and a movable rigid part to which the strip is connected.

[0029] According to a particular embodiment of the invention, the torque or force is continuously adjustable by means of a prestressing means.

[0030] According to a particular embodiment of the invention, the prestressing means comprises a secondary flexible blade connected to the elastic element.

[0031] According to a particular embodiment of the invention, the prestressing means comprises a lever adjusting a variable force or torque.

[0032] According to a particular embodiment of the invention, the elastic element is arranged in series with the strip.

[0033] According to a particular embodiment of the invention, the balance spring extends substantially in one plane.

[0034] According to a particular embodiment of the invention, the regulating means can be activated when the balance spring is attached to the plate of the timepiece movement.

[0035] The invention also relates to a rotary resonator for use in a timepiece movement, in particular including an oscillating weight and a balance spring.

[0036] According to a particular embodiment of the invention, the elastic element is assembled with at least one balance spring stud, for example by driving or screwing. [Brief description of the drawings]

[0037] The objects, advantages and features of the present invention will become apparent upon reading of some embodiments thereof, given by way of non-limiting example only, with reference to the accompanying drawings, in which: [Figure 1] FIG. 1 shows a schematic perspective view of a part of a regulator with a balance spring according to an embodiment of the invention, the regulator being arranged in a timepiece movement. [Diagram 2] FIG. 2 shows a schematic top view of the balance spring of the governor of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] 1 shows a schematic diagram of one embodiment of a resonator or governor 1 arranged in a timepiece movement 10. The timepiece movement 10 includes a plate 21, an inertia block, an elastic return element of the inertia block arranged to oscillate, and a balance cock 22.

[0039] The governor 1 further comprises an annular balance 23 as an inertia block, a balance shaft 24, and a hairspring 25 as an elastic return element.

[0040] The plate 21 is provided with a housing 26 that houses the governor 1, in which the balance 23, the hairspring 25, and the balance cock 22 are arranged one above the other. The balance shaft 24 is arranged in the center of the housing 26 and passes through the centers of the balance 22, the hairspring 25, and the balance cock 22. The balance shaft 24 is held by two shock-resistant bearings 28 that are arranged at both ends of the balance shaft. The first bearing 28 is arranged at the bottom of the housing 26, and the second bearing 28 is arranged at the top of the housing 26 and is held by the balance cock 22 that passes through the top of the housing 26 via the central axis of the housing 26. The balance cock 22 is provided with a through hole in which the second bearing 28 is held.

[0041] As shown in Figures 1 and 2, the balance spring 25 preferably extends substantially in one plane. It comprises a flexible strip 2 wound itself in several coils, the strip 2 having a certain flexibility. An inner end 9 of the strip 2 is integral with or assembled with a support 3, which has a substantially triangular shape and is screwed around the shaft of the balance 23.

[0042] The hairspring 25 further comprises means for adjusting its flexibility, for example the adjusting means being operable by the user, in particular when the regulator is attached to a plate of the timepiece movement.

[0043] The adjustment means comprises an elastic element 5 arranged in series with the strip 2, which connects one end 4, 9 of said strip 2 to a fixed support 17 and is fixed to one of the ends 4, 9 of the strip 2. The elastic element 5 is fixed to the outer end 4 of the strip 2. The inner end 9 of the strip 2 is assembled with the support 3 of the oscillating mass of the resonator. The elastic element 5 is an element distinct from the strip 2. The fixed support 17 is fixed relative to a plate 21.

[0044] The elastic element 5 adds further flexibility to that of the strip 2. Preferably, the elastic element 5 has a lower flexibility than that of the strip 2. The elastic element 5 is here arranged in series with the strip 2.

[0045] The elastic element 5 of the hairspring 25 comprises a flexible blade guide with at least one flexible blade. Here, the guide comprises two non-intersecting flexible blades 11, 12 and a rigid part 18. The flexible blades 11, 12 are connected on the one hand to a fixed support 17 laterally and on the other hand to a rigid part 18 which moves them closer to each other. Thus, preferably, the flexible blades 11, 12 move from the rigid part 18 towards the fixed support 17. The outer end 4 of the strip 2 is connected to the rigid part 18. The fixed support 17 is stationary with respect to the movement 10. The fixed support 17 is L-shaped, with a first arm 46 of the L acting as a link with the flexible blades 11, 12 and a second arm 47 of the L directed towards the opposite side of the non-intersecting strip guide and can be combined with a clock movement.

[0046] The adjustment means of the hairspring 25 further comprise prestressing means 6 which apply a variable force or torque to the elastic element 5. In this way, the flexibility of the hairspring can be adjusted. The torque or force is continuously adjustable by the prestressing means 6. In other words, the torque or force is not limited to an isolated value. This allows the flexibility of the elastic element 5 to be adjusted with high precision.

[0047] The prestressing means 6 comprises a secondary flexible strip 19 arranged along non-intersecting strip guides opposite the rigid portion 18. The secondary flexible strip 19 is arranged tangentially to the strip 2 at the outer end 4.

[0048] The other end of the secondary flexible strip 19 is connected to a curved lever 14 that partially bypasses the strip 2. In addition to the secondary flexible blade 19, the lever 14 is also connected to a semi-rigid structure 27 that is connected to the strip 2. The semi-rigid structure 27 partially deflects when the lever 14 is actuated by a force or torque.

[0049] The force or torque is applied to the free end of the lever 14 15 The lever 14 of the prestressing means 6 thus transmits a variable force or torque via the secondary flexible strip 19 and the semi-rigid structure 27 to the elastic element 5, modifying the flexibility of the balance spring 25.

[0050] According to the invention, the elastic element 5 and the strip 2 are separate and assembled to one another by an assembly means, for example an adhesive.

[0051] Preferably, the elastic element 5 is formed from a first material that withstands assembly processes, such as driving or screwing, that generate stresses induced in the first material.

[0052] Pressing is the process where a first piece is at least partially pressed into the housing of a second piece and held by friction within the housing. In other words, the housing clamps a portion of the first piece.

[0053] Screwing is the process in which two parts are kept assembled by means of a screw, which passes partially through the first and second parts to hold them together.

[0054] The first material is preferably selected from metals or metal alloys such as nickel silver, CuBe2, steel, nickel or nickel-based alloys, e.g. nickel phosphorus NiP or nickel tungsten NiW, or materials used in LIGA processes, such as Ni-based, Co-based, CuNiSn-based alloys, or maraging steels. An example of a cobalt-based spring alloy is phynox®, an example of a maraging steel is Durnico®, and an example of a CuNiSn alloy is ToughMet®.

[0055] Such materials are capable of withstanding the stresses induced by assembly processes such as driving and screwing.

[0056] Preferably, the flexible strip 2 is formed from a second material different from the first material.

[0057] Preferably, the strip 2 is one piece, possibly made of the same material. For example, the second material comprises mostly silicon or silicon oxide, preferably entirely silicon. The flexible strip 2 therefore has the non-magnetic properties of silicon. Alternatively, the second material is Nivarox CT® or Nivachron®, well known to those skilled in the art of watchmaking.

[0058] In a particular example, the prestressing means 6 is also formed from the first material. Thus, the prestressing means 6 and the elastic element 5 are more durable and can be assembled in a process such as driving or screwing.

[0059] These assembly means are better able to withstand the forces or torques generated by the prestressing means 6 .

[0060] The same applies to the free end 15 of the lever 14, which cooperates with the first balance spring stud 34. The first balance spring stud includes a housing which makes it possible to press the free end into it.

[0061] The strip 2 and the elastic element 5 are assembled to one another by gluing at the joint 13. The outer end 4 of the strip 2 is glued to a rigid part 18 of the flexible strip guide of the elastic element 5 at the joint 13. The rigid part 18 comprises, for example, a housing, into which the outer end 4 of the strip 2, which is held by gluing, is inserted.

[0062] The second material, for example silicon or silicon oxide, is more brittle than the first material, so that the outer end 4 cannot be forced into the housing.

[0063] In this situation, bonding is sufficient, since the forces or torques generated by the prestressing means 6 are only applied to the elastic element 5 and not exerted thereon. eye It is.

[0064] The elastic elements 5 and the strips 2 are manufactured in different processes according to the two materials.

[0065] The elastic elements 5 and / or the prestressing means 6 are manufactured for example by a wire erosion process, a laser machining process or laser-waterjet bonding, or a LIGA type lithography process.

[0066] The strip 2 made of the second material is produced, for example, by a deep reactive ion etching process of the DRIE type, in order to obtain in particular a silicon balance spring.

[0067] In the variant of the hairspring made from the same material, for example silicon, the process is preferably a deep reactive ion etching process of the DRIE type.

[0068] A first balance spring stud 34 and a second balance spring stud 35 are shown, which are arranged substantially symmetrically with respect to the balance shaft 24, for example, so as to allow the variable force or torque applied to the balance spring 25, in particular the elastic element 5, to be varied.

[0069] The first balance spring stud 34 cooperates with the free end 15 of the lever 14 and the second balance spring stud 35 cooperates with a second arm 47 of the fixed support 17 .

[0070] The second hairspring stud 35 includes a housing into which a second arm 47 is inserted and held by friction or pressure.

[0071] Alternatively, the second arm 47 is held to the second balance spring stud 35 by a screw, not shown.

[0072] Two balance spring studs 34, 35 are arranged on either side of the prestressing means 6 and the elastic element 5. Furthermore, the two balance spring studs 34, 35 are rigidly connected to the lever 14 and to the fixed member. In other words, the first balance spring stud 34 and the second balance spring stud 35 are fixed to the lever 14 and to the fixed support 17, respectively. The assembly of the balance spring studs and the balance spring 25 is performed, for example, by gluing, brazing, soldering, distortion of a metallic glass or mechanical fastening.

[0073] The movement of the first hairspring stud 34 relative to the second hairspring stud 35 modifies the flexibility of the elastic element 5, since it exerts a more or less substantial force or torque on the lever 14 of the prestressing means 6, changing the flexibility of the flexible element 5 and therefore of the entire hairspring 25.

[0074] An adjustment device, not shown but not part of the invention, makes it possible to move the first balance spring stud 34 relative to the second balance spring stud 35 to vary the torque or force applied to the elastic element 5.

[0075] Of course, the invention is not limited to the embodiments described with reference to the drawings, but variants are possible without departing from the scope of the invention.

Claims

1. A hairspring for use in a timepiece resonator, the hairspring (25) comprising a flexible strip (2) wound itself into several coils, the strip (2) having a given flexibility, the hairspring (25) comprising means for adjusting its flexibility, the adjusting means comprising an elastic element (5) arranged in series with the strip (2), the elastic element (5) connecting one end (4, 9) of the strip (2) to a fixed support (17) so as to add further flexibility to the strip (2), the elastic element (5) having a flexibility less than that of the strip (2), the adjusting means comprising prestressing means (6) for applying a variable force or torque to the elastic element (5) without substantially changing the position of the end (4, 9) of the strip (2), varying only the flexibility of the elastic element (5), A hairspring, characterized in that said elastic element (5) and said strip (2) are separated and assembled to one another by assembly means such that the force or torque generated by said prestressing means (6) is applied only to said elastic element (5).

2. 2. A hairspring according to claim 1, characterized in that the elastic element (5) is made from a first material that is resistant to assembly processes that generate stresses in the first material, such as those induced by driving or screwing.

3. 3. A balance spring according to claim 2, characterized in that the prestressing means (6) are made from the first material.

4. The first material is nickel silver, CuBe ２ 3. A hairspring according to claim 2, characterized in that the material is selected from the group consisting of metals or alloys including maraging steels, steels or nickel-based alloys including at least one of Ni, NiP and NiW, materials for use in the LIGA process including Ni-based, Co-based or CuNiSn-based alloys.

5. 3. A hairspring according to claim 2, characterized in that the strip (2) is made entirely from a second material different from the first material, comprising silicon or silicon oxide.

6. 2. The balance spring according to claim 1, characterized in that the strip (2) and the elastic element (5) are assembled by gluing as an assembly means.

7. 2. A hairspring according to claim 1, characterized in that the elastic element (5) is arranged at the outer end (4) of the strip (2).

8. 2. A hairspring according to claim 1, characterized in that the elastic element (5) comprises a flexible guide having at least one flexible blade with two non-intersecting blades (11, 12) and a movable rigid part (18) to which the strip (2) is connected.

9. 2. A hairspring according to claim 1, characterized in that the torque or force is continuously adjustable by means of the prestressing means (6).

10. 2. A hairspring according to claim 1, characterized in that the prestressing means (6) comprise a secondary flexible blade (19) connected to the elastic element (5).

11. 2. A hairspring according to claim 1, characterized in that the prestressing means (6) comprise a lever (81, 89, 106, 124) for adjusting a variable force or torque.

12. A rotary resonator (1) for use in a timepiece movement including an oscillating weight, characterized in that it includes a balance spring (25) according to claim 1.

13. A timepiece movement comprising a plate and a resonator according to claim 12, characterized in that the elastic element (5) is assembled to at least one balance spring stud (35) by driving or screwing.

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