Flexible guide and assembly of superimposed flexible guides for rotating resonator mechanism, especially for clockwork.

Description

Field of invention

[0001] The present invention relates to a flexible guide for a rotary resonator mechanism. The invention also relates to a set of superimposed flexible guides for a rotary resonator mechanism. The invention also relates to a watch movement provided with such a flexible guide or such a set of superimposed flexible guides. Background of the invention

[0002] Most modern mechanical watches are equipped with a sprung balance and a Swiss lever escapement mechanism. The sprung balance is the watch's time base. It is also called a resonator.

[0003] The exhaust, meanwhile, fulfills two main functions: maintain the back and forth movements of the resonator; count these back and forth movements.

[0004] The Swiss lever escapement mechanism has a low energy efficiency (around 30%). This low efficiency comes from the fact that the escapement's movements are jerky, that there are drops or lost paths to accommodate machining errors, and also from the fact that several components transmit their movement via inclined planes that rub against each other.

[0005] To create a mechanical resonator, an inertial element, a guide, and an elastic return element are required. Traditionally, a balance spring acts as an elastic return element for the inertial element, which is a balance wheel. This balance wheel is guided in rotation by pivots that rotate in ruby ​​plain bearings. This gives rise to friction, and therefore to energy losses and rate disturbances, which depend on the positions, and which we seek to eliminate.

[0006] There are also rotary resonators pivoting around an axis of rotation and subject to a motor torque, which perform a continuous rotary movement around an axis.

[0007] Application EP 17194636.1 describes such a resonator mechanism comprising a plurality of inertial elements movable relative to the central mobile of the resonator, and returned towards its axis of rotation by elastic return means. In rotation, the resonator deploys in a plane perpendicular to the axis of rotation of the resonator.

[0008] Another application EP17183211.6 shows a rotary resonator comprising at least one inertial element arranged to pivot relative to the central mobile around a secondary axis perpendicular to the axis of the central mobile. In rotation, the resonator deploys in a plane containing the axis of rotation of the resonator.

[0009] These applications include embodiments of rotary resonators comprising flexible reed guides as elastic means for returning the inertial element(s). Flexible virtual pivot guides make it possible to significantly improve the efficiency of watch resonators. The simplest are crossed reed pivots, composed of two guide devices with straight reeds that cross, generally perpendicularly. But there are also uncrossed reed pivots of the RCC (for "Remote Center Compliance" in English) type, for which the center of rotation is outside the structure of the pivot, and which have straight reeds that do not cross.

[0010] It is possible to optimize a three-dimensional blade guide for a resonator, in order to try to make it isochronous with a step independent of its orientation in the gravity field. In the case of rotary resonators described in the state of the art, we seek to obtain an elastic restoring moment of the flexible guide, which has a sinusoidal shape. For certain cases of rotary resonators described in the state of the art, the restoring moment allowing to achieve perfect isochronism obeys the following law: M = -ksin ( 2θ ) , Or θ is the guide deformation angle and k a restoring constant. Thus, the restoring moment increases up to a guide deformation angle, for example 45°, then decreases down to another angle, for example 90°.

[0011] However, the flexibly guided rotating resonators described in the state of the art do not meet this requirement, so they do not achieve sufficient isochronism to be efficient. Summary of the invention

[0012] An object of the invention is, therefore, to provide a flexible guide for a rotary resonator mechanism, which avoids the aforementioned problems.

[0013] To this end, the invention relates to a flexible guide for a rotary resonator mechanism, in particular of a clockwork movement, the guide comprising a first support, an element movable relative to the first support, a first pair of flexible blades connecting the first support to the movable element, so that the movable element can move relative to the first support by bending the blades in a circular movement around a center of rotation, the flexible guide being arranged substantially in a plane.

[0014] The flexible guide is remarkable in that it comprises pre-stressing means, the pre-stressing means being configured to apply a buckling force to the flexible blades by bringing the first support closer to the movable element, so that the flexible guide comprises two stable positions of the movable element relative to the first support for which the restoring moment is zero, the two stable positions having a predetermined angle of rotation between them.

[0015] The invention provides a flexible blade guide that can move between two stable positions, and whose behavior is close to an ideal guide for a rotary resonator. Such a flexible guide guarantees isochronism and operation independent of the gravity field. Indeed, the buckling force of the blades makes it possible to transform the linear restoring moment of a flexible guide without constraint into a bistable restoring moment, the restoring moment having a substantially sinusoidal shape, between the two stable angular positions of the moving element.

[0016] According to an advantageous embodiment, the return moment of the flexible guide has a substantially sinusoidal shape between the two stable angular positions.

[0017] According to an advantageous embodiment, the movable element has axial symmetry and a center of rotation, the flexible blades being directed towards the center of rotation.

[0018] According to an advantageous embodiment, the prestressing means comprise a spring connecting the movable element and the first support.

[0019] According to an advantageous embodiment, the flexible guide comprises a second support and a second pair of flexible blades connecting the second support to the mobile element, the second support and the second pair of blades being arranged by symmetry of the first support and the first pair of flexible blades relative to the mobile element, the two pairs of flexible blades connecting on either side the first and second support to the mobile element at its center of rotation.

[0020] According to an advantageous embodiment, the prestressing means comprise a holding member comprising two arms, each arm being fixed to a support, so as to apply the buckling force on one support in the direction of the other support.

[0021] According to an advantageous embodiment, the holding member comprises elastic structures arranged on the arms to be in contact with each support.

[0022] According to an advantageous embodiment, the movable element is partly deformable at the center of rotation.

[0023] According to an advantageous embodiment, each arm of the holding member comprises a deformable portion.

[0024] The invention also relates to a set of superimposed flexible guides comprising at least two flexible guides according to the invention, the supports of the second flexible guide being fixed to the movable element of the first flexible guide.

[0025] According to an advantageous embodiment, the assembly comprises a third flexible guide superimposed on the second flexible guide, the supports of the third flexible guide being fixed to the movable element of the second flexible guide.

[0026] The invention also relates to a rotary resonator mechanism of a watch movement, the mechanism comprising a central wheel arranged to pivot about a central axis and at least two inertial elements arranged to pivot relative to the central wheel about a secondary axis. The mechanism comprises two flexible guides, each flexible guide connecting an inertial element to the central wheel.

[0027] The invention also relates to a rotary resonator mechanism of a watch movement, the mechanism comprising a central wheel arranged to pivot about a central axis and at least two inertial elements arranged to pivot relative to the central wheel about a secondary axis. The mechanism comprises two sets of superimposed flexible guides, each set connecting an inertial element to the central wheel. Summary description of the drawings

[0028] Other characteristics and advantages of the present invention will appear on reading several embodiments given solely as non-limiting examples, with reference to the appended drawings in which: there figure 1 schematically represents a top view of a flexible guide according to a first embodiment of the invention, the figure 2 schematically represents a flexible guide according to a second embodiment of the invention, the figure 3 is a graph representing the elastic restoring moment of the flexible guide as a function of the rotation angle, the figure 4 schematically represents a top view of the flexible guidance of the figure 2 without prestressing, the Figure 5 schematically represents a perspective view of the flexible guide of the first embodiment partly disassembled, the prestressing means being separated from the rest of the guide, the figure 6schematically represents a top view of a flexible guide according to a first variant of the first embodiment, the figure 7 schematically represents a top view of a flexible guide according to a second variant of the first embodiment, the figure 8 schematically represents a top view of a flexible guide according to a third variant of the first embodiment, the figure 9 schematically represents a top view of a set of flexible guides according to an embodiment of the invention, and the figure 10 schematically represents a perspective view of the flexible guide assembly of the figure 9 . Detailed Description of Preferred Embodiments

[0029] On the figure 1, a flexible guide 1 is shown comprising a support 2, a movable element 3 relative to the support 2 and two uncrossed flexible blades 4, 5 connecting the movable element 3 to the support 2. The movable element 3 has the shape of an arc of a circle, the blades 4, 5 being arranged on the internal side of the arc. The blades 4, 5 are of the same length and arranged symmetrically to join the support 2. Without prestressing, the blades 4, 5 are oriented in two directions, which intersect at a point 6 of the support 2, the point 6 defining a center of rotation of the movable element 3. By bending the flexible blades 4, 5, the movable element 3 can move relative to the support 2. The flexible guide 1 is arranged substantially in a plane.

[0030] According to the invention, the flexible guide 1 comprises prestressing means 7 configured to apply a buckling force to the flexible blades 4, 5 by bringing the movable element 3 closer to the support 2. To this end, the prestressing means 7 comprise, for example, a spring fixed on the one hand to the support 2 and on the other hand to the movable element 3. Preferably, the spring is substantially fixed at the center of mass of the movable element 3.

[0031] The spring exerts a tensile force which brings the movable element 3 closer to the support 2. Thus, a buckling force forces the blades to bend to put the movable element 3 in a stable position for which the restoring moment is zero. On the figure 1 , the movable element moves to a stable position to the left of the figure 1. Without prestressing, the movable element 3 is centered on the axis A, while in the stable position induced by the prestressing, the movable element 3 is centered on the axis B. The axis B forms an angle α with the axis A.

[0032] There is a second stable position, not shown in the figure 1 , in which the movable element 3 can be positioned relative to the support, and for which the restoring moment is zero. The second position is symmetrical to the first relative to the axis A, the movable element being displaced to the right forming an angle -α with the axis A. Thus, between the two stable positions, the angle is equal to 2α. Furthermore, the restoring moment of the flexible guide 1 has a substantially sinusoidal shape. Thanks to the prestressing means 7, the movable element 3 can move from one stable position to the other depending on the forces acting on it.

[0033] In an application to a rotary resonator mechanism, such as those described in the applications cited in the preamble, two flexible guides are used to replace those described in these applications. The supports are fixed to the central element, while the movable elements are each fixed to an inertial element.

[0034] THE figure 2 And 5 show a second embodiment of a flexible guide 10 according to the invention. For understanding, we have also shown on the figure 4, the same flexible guide 10 without prestressing means. The flexible guide 10 comprises a first 11 and a second 12 support, a movable element 13 relative to the supports 11, 12, two pairs of uncrossed flexible blades 14, 15, 16, 17 allowing the movable element 13 to move relative to the supports 11, 12. The flexible guide 10 is arranged substantially in a plane. Each pair of blades 14, 15, 16, 17 connects one of the supports 11, 12 to the movable element 13. The blades of a pair 14, 15, 16, 17 join the movable element at a center of rotation 18 of the movable element 13. The supports 11, 12 have a parallelepiped shape provided with a rear block 19, 21. The blades 14, 15, 16, 17 start from two opposite ends of the support 11, 12 towards the middle of the movable element 13. The flexible guide 10 is arranged substantially in a plane.

[0035] The movable element 13 comprises a longitudinal portion 22 and a U-shaped structure 23, 24 at each end of the longitudinal portion 22. Each end is connected to the center of the base of the U of the structure 23, 24. Thus, the movable element 13 has axial symmetry along its longitudinal portion 22. The middle of the longitudinal portion forms the center of rotation 18 of the movable element 14.

[0036] Without prestressing means, as shown in the figure 4, the blades 14, 15, 16, 17 of a pair and the supports 11, 12 have the shape of an isosceles triangle, the main vertex of which is arranged in the middle of the movable element 13. The flexible guide 10 has two perpendicular axes of symmetry X, Y. The first axis X passes longitudinally through the axis of the longitudinal part 22, and the second axis Y passes through the supports 23, 24 so as to divide them into two equal parts. The two axes X, Y also pass through the center of rotation 18 of the flexible guide 10. Thus, the two blades 14, 15, 16, 17 of the same pair are symmetrical with respect to the second axis Y. The two U-shaped structures are also symmetrical with respect to the second axis of symmetry Y. The two supports 11, 12 are symmetrical with respect to the first axis of symmetry X.

[0037] The movable element 22 is configured to be able to rotate around the center of rotation 18 thanks to the flexibility of the blades 14, 15, 16, 17. The center of rotation is arranged substantially at its center of mass. Depending on the actuation of the guide 10, the movable element 13 rotates in the plane of the flexible guide 10. Without prestressing, the elastic restoring moment is linear as a function of the angle of rotation relative to the equilibrium position of the mechanism. In addition, in this case there is only one stable position corresponding to the rest position of the movable element. The movable element is directed along the first axis of symmetry X, as shown in the figure 4 .

[0038] According to the invention, the flexible guide 10 comprises prestressing means 27 configured to apply a buckling force F to the flexible blades 14, 15, 16, 17 by bringing each support 11, 12 closer to the movable element 13. To this end, the flexible guide 10 is provided with a member for holding said supports 11, 12, the holding member forming said prestressing means 27. The holding member has a U-shaped body 25 whose two arms 26, 28, which are substantially parallel, each bear on one of the supports 11, 12. The distance between the two arms is less than the distance between the two supports 11, 12 without prestressing. Thus, the arms 26, 28 press on the supports 11, 12 by applying the force F, which allows the flexible blades 14, 15, 16, 17 to buckle to bring each support 11, 12 closer to the mobile element 13. The buckling force F is directed along the second axis of symmetry Y of the flexible guide 10.Thus, the flexible blades 14, 15, 16, 17 of the two pairs are substantially curved. In response, the movable element 13 moves in rotation through a determined angle α to reach a first stable position. The angle α is defined relative to the first axis of symmetry X, the first stable position being directed upwards on the . figure 2 . Furthermore, the flexible guide 10 has a second stable angular position, not shown in the figures, the movable element 13 moving in rotation by a determined angle -α downwards. The two angular positions are defined with respect to the first axis of symmetry X and form an angle equal to 2α. The second position is symmetrical to the first with respect to the first axis of symmetry X of the flexible guide 10. The values ​​of the angles of the stable positions depend on the force applied by the prestressing means.

[0039] There figure 3shows a graph representing the restoring moment of the flexible guide 10 as a function of the angle of rotation of the movable element 13. Without prestressing means, the flexible guide of the figure 4 , would be a straight line passing through 0. Thanks to the prestressing means 27, the restoring moment describes a substantially sinusoidal function of a period between the two stable positions. The two stable positions 28, 29 correspond to the zero restoring moment and are located at the angle ± a . Thus, the elastic restoring moment of the flexible guide 10 is modified, so that the restoring moment has two stable positions and a substantially sinusoidal shape.

[0040] The movable element 13 can move from one stable position to another depending on the movement followed by the flexible guide 10. In particular in a rotary resonator mechanism, where the flexible guide 10 follows a rotational movement around a main axis of the mechanism. The movable element 13 positions itself in a position depending on the centrifugal force it experiences. Thanks to such a flexible guide 10, the rotational speed of the resonator remains substantially constant, even if the driving force applied to the resonator mechanism varies.

[0041] THE figures 6, 7 And 8 are variants of the second embodiment described previously, and incorporate most of its characteristics.

[0042] In a first variant of the second embodiment of the flexible guide 30, shown in the figure 6, the holding member comprises absorbers 38, 39 made of elastic material. The absorbers 38, 39 are arranged on the arms 26, 28 of the holding member. They have, for example, a U shape whose walls are provided with tabs folded towards the inside of the U. In the operating position, the tabs are arranged on either side of the rear block, resting on the rear face of the support 11, 12. Thus, the tabs can deform when the support 11, 12 is pushed by the flexible blades 14, 15, 16, 17, for example during a change of stable position of the movable element 13.

[0043] The absorbers 38, 39 are arranged at the ends of the walls to be in contact with the supports 11, 12 of the flexible guide 30. Thus, these absorbers 38, 39 make it possible to improve the curvature of the elastic return moment between the stable positions, in order to give them a shape even closer to a sinusoidal function.

[0044] On the figure 7 , a second variant consists in that the longitudinal part 42 of the movable element 33 is partly flexible. The longitudinal part 42 is pierced with a longitudinal oblong through-orifice bordered by two walls. Under the effect of the movement of the movable element from one stable position to the other, the walls curve. In a manner similar to the first variant, the elastic restoring moment describes a function closer to a sinusoidal shape. The longitudinal part 42 comprises insertion tubes 43, 44, 45, 46 on the outer side of the walls for the flexible blades 14, 15, 16, 17.

[0045] A third variant, shown on the figure 8, comprises a holding member provided with a flexible portion 48, 49 upstream of each end of the arms 34, 36. These portions 48, 49 provide flexibility to the arms 34, 36 when the stable position of the mobile element changes. Each flexible portion 48, 49 here comprises two flexible walls 51, 52, 53, 54 separated by a through opening, so that under the effect of the movement of the mobile element 23 and the bending of the blades 14, 15, 16, 17, which pushes on the holding member, the walls deform. In a similar manner to the first two variants, the elastic return moment describes a function closer to a sinusoidal shape.

[0046] The invention also relates to a set 60 of superimposed flexible guides. On the figures 9 and 10, the assembly 60 comprises three flexible guides 61, 62, 63 such as those described in the second embodiment, with the difference that only the first flexible guide 61 comprises a holding member of the second embodiment. The other two flexible guides 62, 63 have different prestressing means. The two supports 67, 68 of the second flexible guide 62 are fixed to the movable element 64 of the first flexible guide 61. The supports 69, 71 of the third flexible guide 63 are fixed to the movable element 65 of the second flexible guide 62. For this, the rear block of each support is inserted into a U-shaped structure of the movable element of the lower guide.

[0047] To apply a stress to the upper flexible guide 62, 63, the distance between the two U-shaped structures of the movable element 64, 65 of the lower movable element is less than the distance between the two supports 67, 68, 69, 71 of the upper guide 62, 63 without prestressing. Thus, the supports 67, 68, 69, 71 of the upper flexible guide 62, 63 are kept compressed between the two U-shaped structures of the movable element 64, 65 of the lower guide 61, 62. The buckling force of the flexible blades is obtained by this interlocking of the supports 67, 68, 69, 71.

[0048] For each flexible guide 61, 62, 63, the angle of travel between the two stable positions is equal to 2 a, a being the angle formed by the position of the movable element with prestressing relative to the position of the movable element without prestressing. 2 ais for example between 20 and 40°, preferably substantially equal to 30°. Thus, by superimposing three devices, an overall angle of 90° is obtained. With such an overall angle, we end up with a flexible guide ideal for use in a clock resonator mechanism.

[0049] In the rest position, the upper flexible guide is oriented in a direction forming an angle corresponding to the angle formed between the two stable positions of the movable element. Thus the second axis of symmetry of the upper flexible guide forms an angle with the second axis of symmetry of the upper flexible guide, for example 30°.

[0050] The invention also relates to a rotary resonator clockwork mechanism, not shown in the figures.

[0051] In a first variant, the resonator mechanism is provided with a flexible guide according to the first or second embodiment.

[0052] In a second variant, the resonator mechanism is provided with a set of superimposed flexible guides according to the invention.

[0053] The flexible guide or set of superimposed flexible guides has the function of allowing the moving masses of the resonator mechanism to move away from the center of rotation, when the rotational force of the mechanism is stronger, or to move closer to it, when the rotational force of the mechanism is weaker. Thus, a substantially constant rotational speed is maintained, whatever the tension of the barrel spring.

[0054] In the examples of rotary resonator mechanism of the applications cited in the preamble, the flexible guides described therein are replaced by a flexible guide according to the invention or a set of superimposed flexible guides according to the invention. For this, the holding member of the lower guide is fixed to the axis, while a support of the upper guide is fixed to the moving mass of the resonator. By symmetry, a second set is assembled in the same way to allow the other moving mass of the resonator to move relative to the center of rotation of the resonator.

[0055] Naturally, the invention is not limited to the embodiments described with reference to the figures and variants could be envisaged without departing from the scope of the invention as defined by the attached set of claims.

Claims

1. A flexible guide for a rotary resonator mechanism, in particular of a horological movement, the guide (1, 10, 30, 40, 50) comprising a first support (2, 11), an element (3, 13) movable relative to the first support (2, 11), a first pair of flexible strips (14, 15) connecting the first support (2, 11) to the movable element (3, 13), so that the movable element (3, 13) can displace relative to the first support (2, 11) by bending the strips (14, 15) in a circular movement about a centre of rotation (6, 18), the flexible guide (1, 10, 30, 40, 50) being arranged substantially in a plane, and comprising prestressing means (7, 27, 37, 47), characterised in that the prestressing means (7, 27, 37, 47) are configured to apply a force for buckling the flexible strips (14, 15) by bringing the first support (2, 11) closer to the movable element (3, 13), so that the flexible guide (1, 10, 30, 40, 50) comprises two stable positions (28, 29) of the element (3, 13) movable relative to the first support (2, 11)for which the return moment is zero, the two stable positions (28, 29) having a predetermined angle of rotation (2 a) therebetween.

2. The flexible guide according to the preceding claim, characterised in that the return moment of the flexible guide (1, 10, 30, 40, 50) has a substantially sinusoidal shape between the two stable angular positions (28, 29).

3. The flexible guide according to claim 1 or 2, characterised in that the movable element (3, 13) has an axial symmetry and a centre of rotation (6, 18), the flexible strips (14, 15) being directed towards the centre of rotation (6, 18).

4. The flexible guide according to the preceding claim, characterised in that the prestressing means (7) comprise a spring connecting the movable element (3) and the first support (2).

5. The flexible guide according to any one of claims 1 to 3, characterised in that it comprises a second support (12) and a second pair of flexible strips (16, 17) connecting the second support (12) to the movable element (13), the second support (12) and the second pair of strips (16, 17) being arranged by symmetry of the first support (11) and the first pair of flexible strips (14, 15) relative to the movable element (13), the two pairs of flexible strips (16, 17) connecting on either side the first and the second support (11, 12) to the movable element (13) at its centre of rotation (18).

6. The flexible guide according to the preceding claim, characterised in that the prestressing means (27, 37) include a holding component comprising two arms (26, 28, 34, 36), each arm being fixed to a support (11, 12), so as to apply the buckling force on one support (11, 12) towards the other support (11, 12).

7. The flexible guide according to claim 5 or 6, characterised in that the holding component comprises elastic structures (38, 39) arranged on the arms (26, 28) to be in contact with each support (11, 12).

8. The flexible guide according to claim 5 or 6, characterised in that the movable element (33) is partly flexible at the centre of rotation (18).

9. The flexible guide according to claim 5 or 6, characterised in that each arm (34, 36) of the holding component comprises a deformable portion (48, 49).

10. A set of superimposed flexible guides, characterised in that it comprises at least two flexible guides (61, 62) according to any one of claims 5 to 9, the supports (67, 68) of the second flexible guide (62) being fixed to the movable element (64) of the first flexible guide (61).

11. The set according to the preceding claim, characterised in that it comprises a third flexible guide (63) superimposed on the second flexible guide (62), the supports (69, 71) of the third flexible guide (63) being fixed to the movable element (65) of the second flexible guide (62).

12. A rotary resonator mechanism, in particular for a horological movement, including a central moving body arranged to pivot about a central axis and two inertial elements arranged to pivot relative to the central moving body about a secondary axis, characterised in that it comprises two flexible guides (1, 10, 30, 40, 50) according to any one of claims 1 to 9, each flexible guide (1, 10, 30, 40, 50) connecting an inertial element to the central moving body.

13. The rotary resonator mechanism, in particular for a horological movement, including a central moving body arranged to pivot about a central axis and two inertial elements arranged to pivot relative to the central moving body about a secondary axis, characterised in that it comprises two sets of superimposed flexible guides (60) according to any one of claims 10 and 11, each flexible guide (60) connecting an inertial element to the central moving body.