Balance for timepiece resonator mechanism provided with lateral inertia adjustment weights

Abstract

The invention relates to a balance wheel (15) for a resonator mechanism (1) in watchmaking, comprising a main arm (6) arranged along a longitudinal axis, the balance wheel (15) including at least one first lateral weight (11) for adjusting the inertia of the balance wheel, the first lateral weight (11) being movably mounted on the main arm (6) of the balance wheel (15) so as to be able to assume a plurality of positions more or less close to the main arm (6) in order to adjust the inertia of the balance wheel (15). The invention also relates to a method for fine-tuning said resonator mechanism.

Description

Scope of the invention

[0001] The invention relates to an adjustable inertia balance wheel for a resonator mechanism in watchmaking.

[0002] The invention also relates to a resonator mechanism for a clockwork movement comprising at least one such balance wheel.

[0003] The invention also relates to a method for developing the resonator mechanism. Background of the invention

[0004] New mechanism architectures make it possible to maximize the quality factor of a resonator, by using flexible guidance with the use of an anchor escapement with a very small lift angle, according to application CH15442016 on behalf of ETA Manufacture Horlogère Suisse and its derivatives, the teachings of which are directly usable in the present invention.

[0005] Application CH5182018 or application EP18168765 in the name of ETA Manufacture Horlogère Suisse describes a watchmaking resonator mechanism, comprising a structure carrying, by a flexible suspension, an anchor block from which is suspended an inertial element oscillating according to a first degree of freedom in rotation RZ, under the action of restoring forces exerted by a virtual pivot comprising first elastic blades each fixed to said inertial element and said anchor block, the flexible suspension being arranged to allow a certain mobility of the anchor block in all degrees of freedom other than the first degree of freedom in rotation RZ in which only the inertial element is mobile to avoid any disturbance of its oscillation, and the stiffness of the other degrees of freedom of the balance wheel than the first degree of freedom in rotation RZ is much greater than the stiffness of the virtual pivot in this same first degree of freedom in rotation RZ.Document EP 3 627 242 A1 discloses a balance wheel for a clockwork resonator mechanism including regulating weights.

[0006] Application CH715526 or application EP3561607 in the name of ETA Manufacture Horlogère Suisse describes a watchmaking resonator mechanism, comprising a structure and an anchor block from which is suspended at least one inertial element arranged to oscillate in a first degree of freedom in rotation RZ around a pivot axis extending in a first direction Z, said inertial element being subjected to restoring forces exerted by a virtual pivot comprising a plurality of substantially longitudinal elastic blades, each fixed, at a first end to said anchor block, and at a second end to said inertial element, each said elastic blade being deformable essentially in a plane XY perpendicular to said first direction Z.

[0007] When the resonator mechanism is operating, the inertial element oscillates around the Z direction in the XY plane with a reference oscillation frequency. In addition, the inertial element can also perform secondary rotational oscillations around the X direction on one hand, and around the Y direction on the other. These secondary oscillations are called "out-of-plane" oscillatory modes, meaning they occur outside the XY plane of the inertial element's primary oscillation.

[0008] These secondary "out-of-plane" oscillations have a more or less limited effect on the operation of the regulating organ.

[0009] However, if the frequency of these secondary oscillations is a multiple of the reference frequency of the inertial element in the XY plane, the secondary oscillations are larger and disrupt the oscillator's operation. Therefore, care must be taken to ensure that the frequency of the secondary oscillations differs from the reference frequency by a multiple of the reference frequency. Summary of the invention

[0010] The invention aims to improve the resonator mechanism of application CH715526 or application EP3561607 in the name of ETA Manufacture Horlogère Suisse to avoid the disadvantages mentioned above.

[0011] To this end, the invention relates to a balance wheel for a resonator mechanism in watchmaking, according to claim 1.

[0012] The balance wheel is remarkable in that it includes at least one first lateral weight for adjusting the inertia of the balance wheel, the first lateral weight being mounted movably on the main arm of the balance wheel so as to be able to take a plurality of positions more or less close to the main arm in order to adjust the inertia of the balance wheel.

[0013] Thanks to this invention, it is possible to adjust the balance wheel to control and avoid significant secondary oscillations around at least one axis, in particular along the X direction passing through the center of mass of the balance wheel, the secondary oscillations occurring in the YZ plane perpendicular to the XY plane of oscillation.

[0014] This or these lateral adjusting weights allow the secondary oscillation frequency to be modified and selected in order to avoid a multiple of the reference oscillation frequency of the balance wheel in the XY plane. Thus, the resonator mechanism equipped with such a balance wheel is more precise.

[0015] Furthermore, the lateral adjustment weights have no noticeable effect on the reference oscillations around the Z direction.

[0016] According to a particular embodiment of the invention, includes a second lateral inertia adjustment weight disposed on the main arm symmetrically to the first lateral weight with respect to the longitudinal axis of the main arm.

[0017] According to a particular embodiment of the invention, the lateral weight(s) are screws.

[0018] According to a particular embodiment of the invention, the lateral weight(s) are offset on the balance arm.

[0019] According to a particular embodiment of the invention, the balance wheel further comprises at least one peripheral inertia adjustment weight, mounted on two ends of the main arm.

[0020] According to a particular embodiment of the invention, the balance wheel includes a hub.

[0021] According to a particular embodiment of the invention, the main arm comprises an enlarged part where the lateral adjusting weight(s) are arranged.

[0022] The invention further relates to a resonator mechanism comprising a structure and an anchor block from which is suspended at least one inertial element arranged to oscillate in a first degree of freedom in rotation RZ around a pivot axis extending in a first direction Z, said inertial element being configured to be subjected to restoring forces exerted by restoring means configured to oscillate the inertial element, the inertial element comprising such a pendulum.

[0023] According to a particular embodiment of the invention, the balance wheel is mounted so that the longitudinal axis is substantially perpendicular to the first direction Z.

[0024] According to a particular embodiment of the invention, the balance wheel is mounted so that the principal plane of the balance wheel is substantially perpendicular to the first direction Z.

[0025] The invention also relates to a method for developing such a clockwork resonator mechanism, the method comprising: a first step of measuring a reference oscillation frequency of the inertial element around the Z direction in the XY plane, a second step of measuring at least one secondary oscillation frequency of the inertial element in the YZ plane around the X direction, a third step of comparing the secondary oscillation frequency to the reference oscillation frequency, to verify that the secondary oscillation frequency has a value substantially different from a multiple of the reference oscillation frequency, and in the case where the secondary oscillation frequency has a value close to or substantially equal to a multiple of the reference oscillation frequency, a fourth step of modifying the position of the adjusting weight(s) relative to the main arm so that the secondary oscillation frequency is substantially different from a multiple of the reference oscillation frequency.

[0026] According to a particular embodiment of the invention, the method includes a fifth verification step, in which the secondary oscillation frequency is measured to verify that the new position of the lateral adjusting weights makes it possible to obtain a value different from a multiple of the reference oscillation frequency. Brief description of the drawings

[0027] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, with reference to the attached drawings, where: there figure 1 represents, schematically and in perspective view, a resonator mechanism with flexible blades comprising a pendulum according to the invention, the figure 2 represents, schematically and in side view, the flexible leaf resonator mechanism of the figure 1 , there figure 3 represents, schematically and from below, the balance wheel according to the invention, and the figure 4represents, in schematic form, a diagram of the process for developing the resonator mechanism according to the invention. Detailed description of preferred embodiments

[0028] The invention relates primarily to a balance wheel and a clockwork resonator mechanism comprising such a balance wheel.

[0029] On the figures 1 and 2 This clockwork resonator mechanism 1 comprises a structure 10 and an anchor block 30, from which is suspended at least one inertial element 2 arranged to oscillate in a first rotational degree of freedom RZ about a pivot axis extending in a first direction Z. The anchor block 30 is suspended from the structure 10 by a flexible suspension 300 equipped with flexible blades, which is arranged to allow the anchor block 30 to move in five flexible degrees of freedom of the suspension, which are: a first degree of freedom in translation along the first direction Z, a second degree of freedom in translation along a second direction X orthogonal to the first direction Z, a third degree of freedom in translation along a third direction Y orthogonal to the second direction X and to the first direction Z, a second degree of freedom in rotation RX around an axis extending along the second direction X, and a third degree of freedom in rotation RY around an axis extending along the third direction Y.

[0030] Structure 10 comprises an upper platform 34 and a lower platform 35, between which the inertial element 2 is suspended.

[0031] This inertial element 2 is subjected to restoring forces exerted by restoring means. In this embodiment, the restoring means are a flexible pivot 200 comprising a plurality of substantially longitudinal elastic blades 3, each fixed at one end to the anchor block 30 and at the other end to the inertial element 2. In the figures, the resonator mechanism 1 comprises two crossed elastic blades 3. An elastic blade 3 is deformable essentially in an XY plane perpendicular to the first Z direction.

[0032] Thanks to the restoring means, the inertial element 2 can oscillate in the XY plane, the first direction Z being perpendicular to the XY plane.

[0033] The inertial element 2 includes a fastener 20 on which the elastic blades 3 are fixed.

[0034] The inertial element 2 further includes a balance wheel 15 assembled to the attachment 20. The balance wheel 15 is elongated in a substantially symmetrical bone shape. The balance wheel 15 includes a main arm 6 arranged along a longitudinal axis of the balance wheel 15 corresponding to the direction X when the mechanism 1 is at rest, and the balance wheel is not oscillating.

[0035] The balance wheel 15 further includes two ends 7, 8 of the main arm 6, which are wider than the main arm 6. The ends 7, 8 and the main arm 6 are, for example, formed of the same material. Alternatively, the ends 7, 8 are mounted on the main arm 6.

[0036] The ends 7, 8 have peripheral weights 9 for adjusting the inertia mounted on each end 7, 8. The first end 7 includes a peripheral weight 9 and the second end 8 includes two axial weights 9. These peripheral weights 9 for adjusting the operation of the resonator mechanism by modifying the inertia of the rocker arm 15, in particular with respect to the Z direction.

[0037] Furthermore, these peripheral weights 9 allow the position of the center of mass of the inertial element 2 to be adjusted along the X and Y directions. The adjustment of the peripheral weights 9 is carried out using a method well known to those skilled in the art. Indeed, it is sufficient to measure the step in the four vertical positions to deduce the displacements required for each of the three peripheral weights 9, using equations known to those skilled in the art.

[0038] Preferably, these peripheral weights 9 are screws whose position can be changed relative to the ends 7, 8.

[0039] The inertial element 2 is configured to oscillate at least in part around a first pivoting pad 5 extending from the upper platform 34 of the structure 10, the pivoting pad 5 being configured to allow the inertial element 2 to pivot around it.

[0040] To this end, the main arm includes a hub 16 into which the first pivot point 5 is inserted. The hub 16 has a larger diameter than the first pivot point 5 to allow the rocker arm 15 to rotate around it. The hub 16 is preferably located in the middle of the arm.

[0041] According to the invention, the balance wheel 15 includes at least one lateral weight 11 for adjusting the inertia of the balance wheel 15, the weight 11 being mounted on the main arm 6. In this embodiment, the balance wheel 15 includes two lateral weights 11 mounted on the main arm 6. The two lateral weights 11 are mounted symmetrically on the main arm 6 with respect to the longitudinal axis of the balance wheel 15.

[0042] These lateral weights 11 are arranged perpendicularly to the longitudinal axis of the main arm 6 in order to modify the oscillation frequency of the main arm 6 around its longitudinal axis. The lateral weights 11 are also movable in the principal XY plane of the balance wheel 16.

[0043] Each lateral weight 11 is movable so that it can take a plurality of positions more or less close to the main arm 6. Thus, the inertia of the balance wheel can be adjusted around the X direction. Indeed, when the weights are moved away from the main arm, the inertia of the balance wheel around the X direction is increased, while when the weights are moved closer to the main arm, the inertia of the balance wheel 15 around the X direction is decreased.

[0044] The lateral weights 11 are screws with a polygonal head and a threaded shank extending from the polygonal head. To increase the adjustment range of the inertia around the X direction, it is possible to manufacture several variants of the lateral weights 11 with heads of different sizes.

[0045] The lateral weights 11 are further offset on the main arm 6 towards the first end 7. The main arm 6 has an enlarged portion 12 where the lateral adjusting weights 11 are arranged. The enlarged portion 12 extends from the first end 7 and includes a central cavity 13 bordered by two lateral walls 14, into which the screws are screwed.

[0046] Thanks to these lateral weights 11, the secondary oscillation frequency of the balance wheel 15 can be modified around the X direction, in particular to avoid a value that is a multiple of the reference oscillation frequency of the balance wheel 15 around the Z direction in the XY plane.

[0047] The inertial element 2 further comprises an anchor 25 assembled beneath the bracket 20, the anchor 25 being centered on the balance wheel 15 and the hub 16. The anchor 25 comprises two main arms 17, 18 in the form of circular arcs, the ends of which are configured to cooperate with an escape wheel, not shown in the figures. The escapement may be of the mechanical type or of the magnetic type, or a combination of the two of the magneto-mechanical type.

[0048] A second pivoting pin 19 extending from the lower platform 35 of the structure 10 is inserted into the anchor 25 along the axis of rotation of the inertial element 2. The anchor 25 includes a second hole 21 into which the second pin 19 is inserted, the second hole 21 being wider than the second pin 19 to prevent any contact between the anchor 25 and the second hole 21. The second pin 19 is arranged along the axis of the first pin 5. Thus, the inertial element 2 surrounds the first 5 and the second pin 19, which are inserted, one into the rocker arm 15 and the other into the anchor 25, so as to allow the oscillation of the inertial element 2 about an axis of rotation passing through the two pins 5 and 19. The amplitude of oscillation of the inertial element 2 in the plane of oscillation is, for example, contained within a interval ranging from 20 to 40°. The oscillation frequency is, for example, greater than ten Hertz.

[0049] The invention also relates to a method of developing 40 a clockwork resonator mechanism such as that presented above, in order to avoid significant secondary oscillations in planes perpendicular to the XY plane, in particular secondary rotary oscillations around the X direction.

[0050] Represented on the figure 4 The method 40 comprises a first step 41 of measuring a reference oscillation frequency of the inertial element 2 around the Z direction in the XY plane. To this end, the number of oscillations of the inertial element 2 per second is measured. For example, a measurement method using a laser measuring system, which is well known to those skilled in the art, is employed.

[0051] In a second step 42, a secondary oscillation frequency of the inertial element 2 is measured in the YZ plane around the X direction.

[0052] A third step 43 consists of comparing the secondary oscillation frequency to the reference oscillation frequency. More precisely, it is checked whether the secondary oscillation frequency has a value that is significantly different from a multiple of the reference oscillation frequency.

[0053] In the case where the secondary oscillation frequency has a value substantially different from a multiple of the reference oscillation frequency, the position of the lateral adjustment weights 11 relative to the main arm 6 is not changed.

[0054] If the secondary oscillation frequency has a value close to or substantially equal to a multiple of the reference oscillation frequency, the method includes a fourth step 44. The fourth step 44 consists of modifying the position of the lateral adjusting weights 11 relative to the main arm 6 so that the secondary oscillation frequency is substantially different from a multiple of the reference oscillation frequency.

[0055] The method may include a fifth verification step 45, in which the secondary oscillation frequency is measured to verify that the new position of the lateral adjusting weights 11 results in a value other than a multiple of the reference oscillation frequency. Thus, if necessary, the position of the lateral weights 11 can be adjusted again if the measured secondary oscillation frequency is not satisfactory.

Claims

1. Balance (15) for a clockwork resonator mechanism (1), including a main arm (6) arranged along a longitudinal axis, the balance (15) comprising at least a first lateral weight (11) for adjusting the inertia of the balance, the first lateral weight (11) being mounted so as to be able to move on the main arm (6) of the balance (15) so as to be able to adopt a plurality of positions more or less close to the main arm (6) in order to adjust the inertia of the balance (15), the lateral flyweight (11) being arranged perpendicular to the longitudinal axis of the main arm (6) in order to be able to modify the frequency of oscillation of the main arm (6) about its longitudinal axis, the lateral weight (11) being movable in the main plane of the balance (15).

2. Balance according to claim 1, characterised in that it comprises a second lateral inertia adjuster (22) arranged on the main arm (6) symmetrically to the first lateral inertia adjuster (11) with respect to the longitudinal axis of the main arm (6).

3. Balance according to any one of the preceding claims, characterised in that the lateral weight or weights (11, 22) are screws.

4. Balance according to any one of the preceding claims, characterised in that the lateral weight or weights (11, 22) are off-centre on the main arm (6) of the balance (15).

5. Balance according to any one of the preceding claims, characterised in that it also comprises at least one axial peripheral weight (9) for adjusting the inertia, mounted on two ends (7, 8) of the main arm (6).

6. Balance according to any one of the preceding claims, characterised in that it comprises a hub (16).

7. Balance according to any one of the preceding claims, characterised in that the main arm (6) includes an enlarged part (12) where the lateral adjustment weight or weights (11, 22) are disposed.

8. Resonator mechanism (1) comprising a structure (10) and an anchoring block (30) from which is suspended at least one inertial element (2) arranged to oscillate with a first rotational degree of freedom RZ about a pivot axis (D) extending in a first direction Z, said inertial element (2) being configured to be subjected to return forces exerted by return means configured to cause the inertial element (2) to oscillate, characterised in that the inertial element (2) comprises a balance (15) according to any one of the preceding claims.

9. Resonator mechanism according to claim 8, characterised in that the balance (15) is mounted so that the longitudinal axis of the main arm (6) is substantially perpendicular to the first Z direction.

10. A resonator mechanism as claimed in claim 8 or 9, characterised in that the balance (15) is mounted so that the main plane of the balance (15) is substantially perpendicular to the first Z-direction.

11. Method (40) for developing a clockwork resonator mechanism (100) according to any one of claims 8 to 10, characterised in that it comprises: - a first step (41) of measuring a reference oscillation frequency of the inertial element (2) about the Z direction in the XY plane, - a second step (42) of measuring at least one secondary oscillation frequency of the inertial element (2) in the YZ plane about the X direction, - a third step (43) of comparing the secondary oscillation frequency with the reference oscillation frequency, to check that the secondary oscillation frequency has a value substantially different from a multiple of the reference oscillation frequency, and in the event that the secondary oscillation frequency has a value close to or substantially equal to a multiple of the reference oscillation frequency, a fourth step (44) of modifying the position of the control weight or weights relative to the main arm so that the secondary oscillation frequency is substantially different from a multiple of the reference oscillation frequency.

12. Method according to claim 11, characterised in that it comprises a fifth verification step (45), in which the secondary oscillation frequency is measured to verify that the new position of the lateral adjustment weights (11) makes it possible to obtain a value other than a multiple of the reference oscillation frequency.

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