Timepiece device comprising a frame and a resonator and timepiece comprising such a device

Abstract

The timekeeping device according to the invention comprises a frame and a resonator. The resonator includes a balance wheel (2; 52; 102) centered on a geometric axis of rotation (A) and extending substantially along a plane perpendicular to said axis (A), and a first and a second elastic blade (4, 5; 54, 55; 104, 105), each connecting the balance wheel (2; 52; 102) to the frame and extending along respective non-parallel axes. The elastic blades (4, 5; 54, 55; 104, 105) are arranged to exert a restoring torque on the balance wheel (2; 52; 102), enabling the balance wheel (2; 52; 102) to oscillate around an equilibrium position. The clockwork device includes at least one bearing fixed relative to the frame and at least one pivot (6a, 6b; 33; 106a, 106b) attached to the balance wheel (2; 52; 102) and coaxial with the geometric axis of rotation (A).The pivot (6a, 6b; 33; 106a, 106b) is arranged to cooperate by contact with the bearing during the regular operation of the resonator so as to guide the pendulum (2; 52; 102) in rotation and to support it.

Description

[0001] The present invention relates to a watchmaking device comprising a frame and a resonator. The watchmaking device is, for example, a watch movement, a part of a watch movement, a module intended to be mounted on a watch movement, or a tourbillon or carousel. EARLIER ART

[0002] In mechanical watches, the energy powering the movement is conventionally supplied by a wound mainspring. This mainspring gradually releases its energy through an escapement mechanism, regulated by a mechanical resonator. In most watch mechanisms, the resonator is a balance wheel and hairspring. This is essentially a spiral spring coupled to a flywheel, or balance wheel; the latter is mounted to pivot around a shaft whose two ends are housed in bearings. The spiral spring, or hairspring, is arranged to return the balance wheel to an equilibrium position around which it can oscillate. The oscillation frequency of a balance wheel and hairspring depends on the moment of inertia of the balance wheel and the restoring torque exerted by the hairspring.

[0003] The oscillations of the balance wheel have a considerable amplitude, generally between 270° and 310°. Indeed, for a balance spring of a given stiffness, the greater the amplitude of the oscillations, the more accurately the watch can tell the time, as the amplitude of the oscillations is the denominator in the formulas expressing isochronism perturbations (see, for example, the book "Traité de construction horlogère" by M. Vermot, P. Bovay, D. Prongué, and S. Dordor, published in 2011 by Presses polytechniques et universitaires romandes). However, the mechanical power required to maintain the oscillations of a balance wheel and balance spring is proportional to the square of the amplitude of the oscillations. In order to reduce the system's energy consumption, it would therefore be useful to have a mechanical resonator with which the amplitude of the oscillations can be reduced while maintaining good accuracy.

[0004] There are also known timepieces equipped with a "flexible pivot" resonator, also called a "pivotless resonator." A flexible pivot resonator is one in which the balance wheel is guided in rotation and supported by an arrangement of elastic parts, rather than by a physical axis of rotation sliding in bearings. For example, patent document WO 2022 / 009102 describes a resonator in which the elastic restoring force acting on the balance wheel comes from two elastic blades extending in parallel planes to intersect without contact. These elastic blades are fixed to the frame at one end and to the balance wheel body at the other. Patent document EP 3792700 describes a resonator comprising several pairs of elastic blades located in the same plane.A primary advantage of flexible pivot resonators is that the amplitude of the balance wheel's oscillations typically does not exceed 30°, while maintaining chronometric precision at least equivalent to that of a balance wheel with a hairspring oscillating between 270° and 310°. Another advantage is that the function of the two elastic blades is not limited to returning the balance wheel to its equilibrium position. Indeed, although the elastic blades deform during the oscillation, they are sufficiently short and rigid to continuously support the mass of the balance wheel and guide its rotation around a virtual axis without the need for bearings, thus avoiding dry friction.

[0005] The resonant frequency of a conventional balance spring is between 3 and 5 Hz. In contrast, in known flexible-pivot resonators, the oscillation frequency is never lower than 12 Hz. It is most often close to 50 Hz. This latter characteristic can prove disadvantageous. Indeed, the mechanical power required to maintain the oscillations of a mechanical resonator varies with the cube of its frequency. Therefore, there is a need for a mechanical resonator in which the amplitude of the oscillations can be reduced compared to the case of the conventional balance spring, while still maintaining a low oscillation frequency. BRIEF SUMMARY OF THE INVENTION

[0006] One object of the present invention is to overcome the drawbacks of the prior art by providing a resonator requiring less power to maintain the oscillations of the balance wheel, thereby increasing the power reserve. The present invention achieves this object, as well as others, by providing a timepiece comprising a frame and a resonator, and conforming to the attached claim 1. The present invention further provides a timepiece, such as a watch, comprising this timepiece.

[0007] According to the invention, the resonator comprises a first and a second elastic blade, each arranged to connect the balance wheel to the frame. These elastic blades extend along their respective non-parallel axes. These elastic blades thus resemble the blades of a flexible pivot and, like the latter, are relatively short. It is these elastic blades that exert the restoring torque on the balance wheel, allowing it to oscillate around an equilibrium position. An advantage of using short elastic blades instead of a balance spring is the ability to achieve good timekeeping at low amplitudes. It should be noted that, as already mentioned, the mechanical power required to maintain the oscillations of a balance wheel resonator is proportional to the square of the amplitude of the oscillations. The present invention therefore makes it possible to reduce the energy consumption of the resonator while maintaining good timekeeping.

[0008] According to the invention, the balance wheel is guided in rotation by at least one pivot rotating in a bearing which serves as its support.

[0009] According to one embodiment, the resonator of the invention comprises, on the one hand, a pair of pivots fixed to the balance wheel, extending from its geometric axis of rotation, and on the other hand, a pair of bearings fixed relative to the frame and arranged to cooperate by contact with one of the two pivots, so as to guide and support the balance wheel's rotation around its axis. It should be noted that this arrangement of two pivots is similar to that generally used with a traditional balance wheel and hairspring. With such an arrangement, depending on the orientation of the timepiece relative to gravity, either only one of the two pivots is in contact with the corresponding bearing, or both pivots are in contact with the two bearings respectively, during the normal operation of the timepiece (i.e., even in the absence of shocks or accelerations received by the timepiece).

[0010] According to another embodiment, the resonator of the invention comprises a bearing that is fixed relative to the frame, and a pivot that is integral with the balance wheel. The pivot is aligned with the geometric axis of rotation of the balance wheel and is arranged to cooperate by contact with the bearing so as to guide the balance wheel in rotation around its axis and to support it during the regular operation of the timekeeping device (therefore even in the absence of shocks or accelerations received by the timekeeping device).

[0011] In both embodiments, the contact between the pivot(s) and the bearing(s) can be direct or indirect. For example, it can occur via moving elements such as balls or rollers.

[0012] In summary, according to the invention, the resonator's pendulum is guided in rotation by at least one pivot engaged to rotate within a bearing that serves as its support. Therefore, the parts that cause the pendulum to oscillate around its equilibrium position and that support it to guide its rotation are not the same. The invention thus offers the advantage of allowing, for example, a reduction in the stiffness of the elastic blades that exert the restoring torque on the pendulum, and thereby lowering the resonant frequency compared to a resonator with a flexible pivot. The invention also offers the advantage of allowing a heavier pendulum regardless of the stiffness of the elastic blades. It should be noted in this regard that a heavier pendulum can have a greater moment of inertia and therefore resonate at a lower frequency.As already mentioned, the mechanical power required to maintain the oscillations of a mechanical resonator is proportional to the cube of its frequency. BRIEF DESCRIPTION OF THE FIGURES

[0013] Other features and advantages of the present invention will become apparent from the following detailed description, made with reference to the accompanying drawings, in which: there figure 1 is a perspective view of a clockwork resonator according to a first embodiment of the invention; the figure 2 is a perspective view of a clockwork resonator according to a variant of the first embodiment of the invention; the figure 3 is a perspective cross-sectional view of a clockwork resonator according to a second embodiment of the invention; the figure 4 is a perspective view of a clockwork resonator according to a third embodiment of the invention. DETAILED DESCRIPTION OF IMPLEMENTATION METHODS

[0014] There figure 1 This is a perspective view of a watch resonator according to a first embodiment of the invention. The resonator shown is intended for use in a watch. It comprises, firstly, a balance wheel 2 which is attached to a balance staff 3 in the form of a crankshaft. It can be seen that the two ends of the staff 3 each carry a pivot (referenced respectively as 6a and 6b), the two pivots being coaxial. It will be understood that the axis common to the pivots 6a and 6b coincides with the geometric axis of rotation A of the balance wheel. The balance wheel 2 is centered on said geometric axis A, and it extends substantially in a plane perpendicular to it. As is well known to those skilled in the art, the two pivots are designed to rotate in two bearings (not shown) which are fixed to the watch case.Traditionally, the pivots 6a and 6b shown are in the form of small cylinders, each connected to one end of the balance shaft 3 by means of a fillet and a tenon 7. The two bearings, for their part, conventionally comprise a domed jewel and a counter-pivot jewel (not shown). Each pivot 6a and 6b is inserted into the hole of one of the domed jewels and bears against the counter-pivot jewel with its rounded end.

[0015] The resonator in this example also includes a support 1, which is fixed to the watch frame (not shown), and two elastic blades 4 and 5 whose function is to elastically connect the balance wheel 2 to the support 1, and therefore to the frame. Although identical in shape, the elastic blades 4 and 5 extend in distinct parallel planes and in different directions, intersecting without touching. These two parallel planes are oriented perpendicularly to the geometric axis of rotation A of the balance wheel, so that the elastic blades intersect the geometric axis of rotation A perpendicularly and at different heights. It can be seen that the support 1 is approximately in the shape of an isosceles triangle, and that the two elastic blades 4 and 5 are arranged symmetrically with respect to this triangle, each blade being fixed to one of the vertices of the triangle by one of its ends, and fixed to the body of the balance wheel by the other end.It can also be seen that the isosceles triangular support 1 has a vertical plane of symmetry and that this plane contains the geometric axis of rotation A of the balance wheel 2. The construction just described is explained in more detail in the aforementioned patent document WO 2022 / 009102. This document is incorporated by reference into the present patent application. The elastic blades 4, 5 serve to exert an elastic restoring torque on the balance wheel 2, tending to return it to an angular equilibrium position. It will also be understood that the resonator of the present invention differs from that described in document WO 2022 / 009102, in particular, in that the elastic blades do not need to be sufficiently stiff to hold the balance wheel suspended, nor to guide its rotation around a virtual axis of rotation, since the balance wheel of the present invention is physically pivoted within the watch case by means of the balance staff 3.

[0016] The resonator illustrated at the figure 1 is formed from a stack of parts comprising an upper part, a lower part, and, between the two, the balance wheel 2. The upper part comprises an upper stage 8 of the support 1, the first elastic blade 4, and an upper oscillating arm 9 which is carried by the balance wheel 2 and connected to the upper stage 8 of the support 1 by the first elastic blade 4. Similarly, the lower part comprises a lower stage 10 of the support 1, the second elastic blade 5, and a lower oscillating arm 11 on which the balance wheel 2 rests and which is connected to the lower stage 10 of the support 1 by the second elastic blade 5. Preferably, the upper part formed by parts 8, 4, and 9 and the lower part formed by parts 10, 5, and 11 are both monolithic. They can, for example, each be made by etching a block of silicon.

[0017] The balance wheel 2 shown is a classic circular metal balance wheel comprising a rim 12 and a diametrical arm 13. Traditionally, the rim 12 carries weights 12a allowing adjustment of the inertia and imbalance. As already mentioned, the balance wheel 2 is fixed to the balance staff 3. Referring to the figure 1 As can be seen, shaft 3 has the shape of a crankshaft with an eccentric midsection. At rest, the elastic blades 4 and 5 are straight, and the eccentric midsection of the balance shaft 3 lies in the aforementioned vertical plane of symmetry, which also contains the geometric axis of rotation A. When the balance wheel 2 deviates from its angular equilibrium position, the eccentric midsection moves away from the plane of symmetry, and the elastic blades 4 and 5 bend, producing a restoring torque that tends to return the balance wheel 2 to its equilibrium position. It will be understood that, thanks to its eccentric midsection, the balance shaft 3 can pass completely through the resonator without interfering with the elastic blades 4 and 5, even though the elastic blades intersect the geometric axis of rotation A of the balance wheel 2.

[0018] Another advantage of the described construction is that it protects the elastic blades 4 and 5 from excessive deformation. Indeed, in the event of excessive rotation of the rocker arm 2 around its axis, following an impact, the diametrical arm 13 can come to rest against the support 1 before the elastic limit of the elastic blades 4 and 5 is exceeded.

[0019] The diametrical arm 13 of the balance wheel is sandwiched between the upper oscillating arm 9 and the lower oscillating arm 11. As shown in the figure 1 Assembly pins 17 pass through elastic ends of the swing arms 9 and 11 and through holes in the diametrical arm 13 as well as through holes in a lower support arm 14 which forms a single piece, preferably monolithic, with the balance shaft 3. The assembly formed by the upper swing arm 9, the balance 2 (via its diametrical arm 13), the lower swing arm 11, the balance shaft 3 and the lower support arm 14 forms a rigid oscillating assembly.

[0020] It will be understood that the elastic blades 4, 5 are similar to those of a flexible pivot resonator, in particular in that they are relatively short and can work at low amplitude with good chronometric precision unlike spirals, but that they are less stiff (for example thinner and / or less high) than those of flexible pivot resonators, which reduces the oscillation frequency compared to the latter.

[0021] There figure 2 shows a variant of the watch resonator according to the first embodiment of the invention. In this variant, the balance tree no longer has the shape of a crankshaft but is made up of two disjoint parts 3a, 3b carrying the two pivots 6a, 6b respectively and each forming a single piece, preferably monolithic, with respectively an upper arm 15a and a lower arm 15b assembled to the oscillating arms 9, 11 and to the diametral arm 13 by the pins 17.

[0022] There figure 3 is a perspective cross-sectional view of a clockwork resonator according to a second embodiment of the invention. The resonator shown shares many characteristics with the resonators of the figures 1 et 2 This is why only the characteristics that distinguish the resonator in the present example from those in the first embodiment are described in detail. It should also be noted that, in the figure 3 , the elements that have already been described in relation to the figure 1 They receive the same reference number plus 50. The resonator shown is designed to be fitted to a watch. It comprises, firstly, a balance wheel 52 which has a center through which passes the geometric axis of rotation A of the balance wheel, and it can be seen that the balance wheel extends substantially in a plane perpendicular to said axis. A single pivot 33 is rigidly fixed to one of the faces of the balance wheel 52 (the lower face in the drawing), and the axis of the pivot is aligned with the geometric axis of rotation A of the balance wheel. The pivot 33 constitutes the rotating inner part of a ball bearing, the outer part 32 of which is fixed relative to the watch frame 31. Thus, the pivot 33 is guided in rotation within the outer part 32 by balls. It can be seen that the ball bearing alone supports the balance wheel 52 and guides its rotation.By comparing the resonator in the present example with that of the previous examples, we can see that the second embodiment allows us to use only one stage instead of two.

[0023] The resonator illustrated at the figure 3 is formed of a stack of parts including the balance wheel 52 which forms the lower level of the stack (as shown in the figure), a part, called lower, which is placed on the balance wheel, and a part, called upper, which is placed on top of the lower part and which is spaced from the latter by spacers (not referenced). The upper part comprises an upper stage 58 of a support 51, a first elastic leaf 54, and an upper swing arm 59 which is connected to the upper stage 58 of the support 51 by the first elastic leaf 54. Similarly, the lower part comprises a lower stage 60 of the support 51, a second elastic leaf 55, and a lower swing arm 61 which is connected to the lower stage 60 of the support 51 by the second elastic leaf 55. The support 51, the elastic leaves 54, 55, and the swing arms 59, 61 are similar to those of the first embodiment.It will be understood, however, that according to this second embodiment of the invention, the two elastic blades 54, 55 are located on the same side of the balance wheel 52 (the side opposite to that which carries the pivot 33). This feature does not prevent the assembly formed by the upper oscillating arm 59, the lower oscillating arm 61 and the balance wheel 52 from constituting a single rigid unit capable of oscillating.

[0024] One advantage associated with using a single bearing to guide the rotating pendulum is that the resonator does not need to be equipped with a pendulum shaft, which completely eliminates the risk of interference with the elastic blades 54, 55 and limits the height footprint.

[0025] There figure 4 is a perspective view of a clockwork resonator according to a third embodiment of the invention. The resonator shown has many characteristics in common with the resonators of the figures 1 à 3 This is why only the characteristics that distinguish the resonator in this example from those in previous examples are described in detail. It should also be noted that, in the figure 4 , the elements that have already been described in relation to the figure 1 They receive the same reference number plus 100. The resonator shown is designed to be fitted to a watch. It comprises, firstly, a balance wheel 102 which has two flywheels in the form of straight circular cylinders (referenced 102a and 102b respectively). The two circular cylinders have the same height and diameter and are arranged coaxially along the geometric axis of rotation A of the balance wheel.

[0026] As was already the case with the previous examples, the resonator of the figure 4is formed from a stack of parts. These parts include on the one hand the two circular cylinders which are arranged at the two ends of the stack, and on the other hand an upper part and a lower part which are both arranged in the space between the two cylinders and spaced apart from each other by spacers (not referenced). The upper part includes an upper stage 108 of a support 101, a first elastic leaf 104 and an upper swing arm 109 which carries the flywheel 102a and which is connected to the upper stage 108 of the support by the first elastic leaf 104. Similarly, the lower part includes a lower stage 110 of the support 101, a second elastic leaf 105 and a lower swing arm 111 which rests on the flywheel 102b and which is connected to the lower stage 110 of the support 101 by the second elastic leaf 105.The support 101, the elastic blades 104, 105 and the oscillating arms 109, 111 are similar to those of the first embodiment. However, it will be understood that according to this third embodiment of the invention, the two elastic blades 104, 105 are located between the two flywheels 102a and 102b.

[0027] As can be seen, the two right-hand circular cylinders 102a and 102b each carry a pivot (referenced 106a and 106b, respectively). These two pivots are coaxial and aligned along the geometric axis of rotation A of the balance wheel 102. Conventionally, the two pivots are designed to rotate in two bearings (not shown) that are fixed to the watch case. It will also be understood that the two flywheels 102a and 102b are rotationally coupled, so that they oscillate together. Indeed, the assembly formed by the flywheel 102a, the upper oscillating arm 109, the lower oscillating arm 111, and the flywheel 102b constitutes a rigid unit.

[0028] In the embodiments described above, the elastic blades are so-called separate crossed blades, which extend in parallel planes and in different directions to intersect without contact. In other embodiments of the invention, the elastic blades could, for example, be so-called non-separated crossed blades (extending in the same plane and therefore physically intersecting) or pivot blades with a remote center of rotation, known as "RCC" (Remote Center Compliance), which do not intersect but extend along respective axes that do intersect. In all cases, the crossing of the blades or their axes preferably occurs substantially on the geometric axis of rotation of the balance wheel. However, it can occur at a distance from the geometric axis of rotation of the balance wheel, as illustrated, for example, in Figure 6, item 16, of patent document EP 4163735.The resonator according to the invention may comprise more than two elastic blades, as for example in said figure 6 of document EP 4163735 or as described in patent document EP 3792700 where a resonator with several pairs of RCC elastic blades is proposed.

[0029] The power consumed by a resonator can be formulated as follows: P d i s s i p é e = Inertie ∗ amplitude 2 ∗ 2 ∗ π ∗ f r é quence 3 2 ∗ Q where the power consumed / dissipated is expressed in W, the inertia of the balance wheel is expressed in kg.m², the oscillation amplitude is expressed in radians, the oscillation frequency is expressed in Hz, and the quality factor Q is dimensionless. Because the oscillation amplitude can be greatly reduced compared to a conventional balance wheel and hairspring, for example by bringing it to the level of the oscillation amplitude of a conventional flexible pivot resonator, and because the oscillation frequency can be greatly reduced compared to a conventional flexible pivot resonator, for example by making it closer to that of a conventional balance wheel and hairspring than to that of a conventional flexible pivot resonator, the power consumed can be much lower in the present invention than with conventional resonators.Typically, power values ​​of 0.05 µW or less can be achieved, compared to typical values ​​of approximately 0.50 µW for a conventional balance wheel and hairspring, and approximately 1 µW for a conventional flexible pivot resonator. The power reserve of the timepiece incorporating the horological device according to the invention can therefore be significantly improved.

[0030] Advantageously, in the present invention the oscillation frequency of the resonator is at most 12 Hz, preferably at most 11 Hz, preferably at most 10 Hz, preferably at most 9 Hz, preferably at most 8 Hz, and the maximum oscillation amplitude of the pendulum during regular operation of the resonator is at most 35°, preferably at most 30°.

Claims

1. A clockwork device comprising a frame and a resonator, the resonator comprising: - a balance wheel (2; 52; 102) centered on a geometric axis of rotation (A) and extending substantially along a plane perpendicular to said axis (A); - a first and a second elastic blade (4, 5; 54, 55; 104, 105) each connecting the balance wheel (2; 52; 102) to the frame and extending along respective non-parallel axes, the elastic blades (4, 5; 54, 55; 104, 105) being arranged to exert on the balance wheel (2; 52; 102) a restoring torque enabling the balance wheel (2; 52; 102) to oscillate around an equilibrium position; characterized in thatit includes at least one bearing fixed relative to the frame and at least one pivot (6a, 6b; 33; 106a, 106b) integral with the balance wheel (2; 52; 102) and coaxial with the geometric axis of rotation (A), the at least one pivot (6a, 6b; 33; 106a, 106b) being arranged to cooperate by contact with the at least one bearing during the regular operation of the resonator so as to guide the balance wheel (2; 52; 102) in rotation and to support it.

2. Clockmaking device according to claim 1, characterized in that it includes two so-called bearings and two so-called pivots (6a, 6b; 106a, 106b).

3. Clockmaking device according to claim 2, characterized in that the two bearings are arranged on either side of the balance wheel (2; 102).

4. Clockmaking device according to claim 2 or 3, characterized in that it includes a rocker arm (3) whose ends carry the two pivots (6a, 6b), this rocker arm (3) comprising an eccentric median portion.

5. Clockmaking device according to claim 2 or 3, characterized in that the pendulum (102) comprises two fixed flywheels (102a, 102b), respectively carrying the two pivots (106a, 106b) and located on either side of the first and second elastic blades (104, 105).

6. Clockmaking device according to claim 1, characterized in that it comprises a single said bearing (32) and a single said pivot (33).

7. Clockmaking device according to claim 6, characterized in that the bearing (32) and the pivot (33) are respectively made up of two parts of a bearing.

8. A clockwork device according to any one of the preceding claims, characterized in that said non-parallel axes substantially intersect the geometric axis of rotation (A).

9. A clockwork device according to any one of the preceding claims, characterized in thatthe first and second elastic blade (4, 5; 54, 55; 104, 105) extend in parallel planes and cross without contact.

10. Clockmaking device according to claim 9, characterized in that the resonator comprises a first oscillating part (9; 59; 109) made of material with the first elastic blade (4; 54; 104), a second oscillating part (11; 61; 111) made of material with the second elastic blade (5; 55; 105), and in that the balance wheel (2; 52; 102) is connected to the first and second elastic blade (4, 5; 54, 55; 104, 105) by assembling the balance wheel with these first and second oscillating parts.

11. Clockmaking device according to claim 10, characterized in that the first and second oscillating parts (9, 11; 59, 61; 109, 111) are arms.

12. A clockwork device according to any one of the preceding claims, characterized in thatthe resonant frequency of the resonator is at most 12 Hz, preferably at most 11 Hz, preferably at most 10 Hz, preferably at most 9 Hz, preferably at most 8 Hz.

13. Timepiece comprising a timekeeping device according to one of the preceding claims.

14. Timepiece according to claim 13, characterized in that The maximum oscillation amplitude of the pendulum during regular operation of the resonator is at most 35°, preferably at most 30°.

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