IMPACT STRIKING MECHANISM, IN PARTICULAR FOR TIMEPIECES

Abstract

An impact striking mechanism (1), in particular for a horological movement (3), the mechanism (1) including at least one resonant element (5) enabling a sound to be emitted when it is struck, and a hammer (8) capable of moving between a rest position (9) and a strike position (11) in which it strikes the resonant element (5) in order to cause it to vibrate, characterised in that it comprises a system for actuating the hammer (8) including a movable impactor (16, 17, 18) configured to move from a release position (19) to an impact position (21), in which it at least partially transmits the momentum thereof to the hammer (8) to move it from the rest position (9) thereof to the strike position (11) thereof in order to cause the resonant element (5) to vibrate.

Claims

1. An impact striking mechanism (1), in particular for a horological movement (3), the mechanism (1) comprising: at least one resonant element (5) enabling a sound to be emitted when struck; a hammer (8) movable between a rest position (9) and a strike position (11) at which the hammer strikes the resonant element (5) in order to cause the resonant element to vibrate; and a system for actuating the hammer (8) including a movable impactor (16, 17, 18) configured to move from a release position (19) to an impact position (21), in which the impactor at least partially transmits the momentum thereof to the hammer (8) to move it from the rest position (9) thereof to the strike position (11) thereof in order to cause the resonant element (5) to vibrate.

2. The striking mechanism according to claim 1, further comprising a magnet (15) which is fixed relative to the horological movement (3), the magnet (15) being configured to attract the movable impactor (16, 17, 18) into an impact position (21).

3. The striking mechanism according to claim 2, wherein the hammer (8) is in contact with the magnet (15) in the rest position (9) thereof.

4. The striking mechanism according to claim 3, wherein the impactor (16, 17, 18) is configured to impact the magnet (15) in order to impart a pulse to the hammer (8) via the magnet (15).

5. The striking mechanism according to claim 4, wherein the distance between the release position (19) of the movable impactor (16, 17, 18) and the magnet (15) is chosen such that the magnet (15) attracts the movable impactor (16, 17, 18) there against in the impact position (21) thereof.

6. The striking mechanism according to claim 4, wherein the momentum transmitted by the movable impactor (16, 17, 18) overcomes the magnetic retaining force of the magnet (15) acting on the hammer (8), such that the hammer (8) detaches from the magnet (15) and strikes the resonant element (5).

7. The striking mechanism according to claim 1, further comprising a flexible guide (12) on which the hammer (8) is mounted to allow the hammer to move between the rest position (9) thereof and the strike position (11) thereof.

8. The striking mechanism according to claim 1, wherein the actuation system comprises a flexible guide on which the movable impactor (16, 17, 18) is mounted to enable the impactor to move between the release position (19) and the impact position (21).

9. The striking mechanism according to claim 7, wherein the flexible guide (12) includes a flexible strip (13, 26, 27, 28) or a flexible neck.

10. The striking mechanism according to claim 1, wherein the actuation system comprises a rotary device (20) equipped with the movable impactor (16, 17, 18), the rotary device being configured to bring the movable impactor (16, 17, 18) into the release position (19).

11. The striking mechanism according to claim 7, wherein the actuation system comprises at least one additional impactor (16, 17, 18) arranged on the rotary device (20), so as to alternately bring each movable impactor (16, 17, 18) into the release position (19).

12. The striking mechanism according to claim 1, wherein the rotary device (20) comprises a hub (22).

13. The striking mechanism according to claim 7, wherein the rotary device (20) comprises at least one arm (22, 23, 24), with each arm (22, 23, 24) bearing a movable impactor (16, 17, 18).

14. The striking mechanism according to claim 7, wherein the rotary device (20) comprises a plurality of arms (22, 23, 24) angularly distributed around the hub (22).

15. A horological movement (3), comprising a striking mechanism (1) according to claim 1.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0030] Other specific features and advantages will be clearly observed in the following description, which is given as a rough guide and in no way as a limiting guide, with reference to the accompanying drawings, wherein:

[0031] FIG. 1 is a diagrammatic view of a timepiece including an impact striking mechanism according to one embodiment of the invention;

[0032] FIG. 2 is an enlarged diagrammatic view of the striking mechanism in FIG. 1;

[0033] FIG. 3 is a diagrammatic view of the striking mechanism in FIG. 1, showing the impactor in the release position;

[0034] FIG. 4 is a diagrammatic view of the striking mechanism in FIG. 1, showing the impactor in the impact position with the magnet and showing the hammer in the strike position with the gong; and

[0035] FIG. 5 is a diagrammatic view of the striking mechanism in FIG. 1, showing the impactor no longer in the impact position, nor in the release position, and showing the hammer having returned to the rest position.

DETAILED DESCRIPTION OF THE INVENTION

[0036] As explained hereinabove, the invention relates to an impact striking mechanism 1. The striking mechanism 1 is intended for a timepiece 10, such as a watch shown in FIG. 1. The timepiece 10 comprises a middle 2 and a horological movement 3, preferably a mechanical movement, which is for example provided with a plate 4 and a barrel spring to supply the operating energy. The embodiment described hereinbelow is based on the combination of the “Gaussian magnetic cannon” principle and the principle of conservation of momentum during a collision.

[0037] In FIGS. 1 to 5, the striking mechanism 1 comprises a resonant element 5, for example a gong conventionally used in horological striking mechanisms. The resonant element 5 allows a sound to be emitted when struck. In the figures, the resonant element 5 is a rod comprising a rectilinear portion 6. The resonant element 5 is preferably fixed to the plate 4, so as to extend above and beside the plate 4, for example in a plane parallel to that of the plate.

[0038] Other configurations of the resonant element 5 are possible. The resonant element 5 can further comprise a circular portion 7, shown in FIG. 1, in particular running along the inner face of the middle 2.

[0039] To emit a sound, the mechanism 1 comprises a hammer 8 that is capable of moving relative to the plate 4. The hammer 8 is capable of moving between two positions, a rest position 9 away from the resonant element 5, and a strike position 11 in which it strikes the resonant element to cause it to vibrate. Thus, the resonant element 5 produces a vibration that propagates through the watch. The outer part of the watch radiates these vibrations such that a sound is emitted. Other embodiments are possible with various forms for the hammer 8 and the resonant element 5.

[0040] The mechanism 1 in this case comprises a flexible guide 12 on which the hammer 8 is mounted to allow it to move between the rest position 9 thereof and the strike position 11 thereof. The flexible guide 12 preferably comprises a first flexible strip 13 assembled with the plate 4 on the one hand, and with the hammer 8 on the other hand. The first flexible strip 13 is preferably arranged substantially parallel to the resonant element 5 when the hammer 8 is in the rest position 9. Through the elastic deformation of the first flexible strip 13, the hammer 8 moves from the rest position 9 into the strike position 11 and vice versa.

[0041] The mechanism 1 further includes a magnet 15 that is fixed relative to the plate 4. The magnet 15 is preferably assembled on the plate 4. The magnet 15 is, for example, disposed on a promontory 14 facing the resonant element 5.

[0042] Preferably, the magnet 15 is configured to retain the hammer 8 in the rest position 9 thereof. For this purpose, the hammer 8 includes a magnetically conductive material, which induces an attractive force on the hammer 8 against the magnet 15.

[0043] Alternatively, a hammer 8 can be chosen that does not comprise any magnetically conductive material. In such a case, the flexible guide 12 is configured to apply a prestressing to the hammer 8, so as to press it against the magnet 8.

[0044] Thus, in the rest position 9, the hammer 8 is in contact with a front face 29 of the magnet 15. The hammer 8 remains in this position at all times, except in the moments when it strikes the resonant element 5. The flexible guide 12 is assembled to the plate 4 between the promontory 14 and the resonant element 5. Thus, the hammer 8 can move between the magnet 15 and the resonant element 5 thanks to the flexible guide 12.

[0045] The front face 29 preferably has a substantially planar surface. The hammer 8 has, for example, a cylindrical or spherical shape. These rounded shapes make it easier to separate the hammer 8 from the front face 29 of the magnet 15.

[0046] According to the invention, the mechanism 1 comprises a system for actuating the hammer 8. This mechanism is configured to cause the hammer 8 to move from the rest position 9 thereof to the strike position 11 thereof. In particular, it serves to separate the hammer 8 from the magnet 15 and allow it to reach the resonant element 5.

[0047] To this end, the actuation system 20 includes at least one movable impactor 16, 17, 18 configured to transmit to the hammer 8 a sufficient momentum to move it from the rest position 9 thereof to the strike position 11 thereof and to cause the resonant element 5 to vibrate.

[0048] The impactor 16, 17, 18 is configured to move from a release position 19 into an impact position 21 wherein it transmits a momentum to the hammer 8.

[0049] In the embodiment shown in FIGS. 1 to 5, the actuation system comprises a rotary device 20 provided with three movable impactors 16, 17, 18.

[0050] The rotary device 20 comprises a hub 22 and three arms 23, 24, 25, which are angularly distributed around the hub 22 and are connected to the hub 22 by one end. Each arm 23, 24, 25 bears a movable impactor 16, 17, 18 disposed at the opposite end of the arm 23, 24, 25 relative to the hub 22. The arms 23, 24, 25 are preferably arranged in the same plane substantially perpendicular to the axis of the hub 22. This plane preferably further passes through the magnet 15, the hammer 8 and the resonant element 5.

[0051] Each movable impactor 16, 17, 18 is mounted on an arm 23, 24, 25 so as to form an angle with the arm 23, 24, 25. The angle is comprised between 30 and 60°, when the movable impactor 16, 17, 18 is in the release position 19, and the angle is comprised between 60 and 90°, when the movable impactor 16, 17, 18 is in the impact position 21. An arm can, for example, be an oblong body, a tooth of a gear train or a small plate.

[0052] Preferably, each movable impactor 16, 17, 18 is mounted on the arm 23, 24, 25 by a flexible guide to enable it to move relative to the arm 23, 24, 25, and to switch from the release position 19 into the impact position 21. The flexible guide here includes a second flexible strip 26 assembled to the movable impactor 16, 17, 18 on the one hand and to the end of the arm 23, 24, 25 on the other hand.

[0053] Each movable impactor 16, 17, 18 comprises a contact face 31, 32, 33, which is intended to come into contact with the magnet 15, when it moves from the release position 19 into the impact position 21. The contact faces 31, 32, 33 of the movable impactor 16, 17, 18 are preferably rounded, to allow for easier disengagement when the movable impactor 16, 17, 18 returns to the release position thereof.

[0054] When the rotary device 20 rotates, it positions one of the movable impactors 16, 17, 18 to face the magnet 15. The movable impactor 16, 17, 18 then moves from the release position 19 into the impact position 21 in a radial movement. Once the impact has been made, the rotary device 20 continues to rotate in order to prevent the movable impactor 16, 17, 18 from remaining against the magnet 15. The geometry of the movable impactors 16, 17, 18 is designed to require as little torque as possible on the rotary device 20. For example, a contact face 32 is chosen that has a gradient tangential to the rotary motion.

[0055] The rotary device 20 is actuated by rotating the hub 22 about the axis thereof, such that the arms 23, 24, 25 rotate about the axis of the hub 22. Thus, the movable impactors 16, 17, 18 also rotate about the axis of the hub 22 while remaining in the release position 19. In other words, the movable impactors 16, 17, 18 remain in the same position relative to the arms 23, 24, 25 bearing them.

[0056] In order to rotate, the means 22 are mechanically connected to the barrel of the movement via meshing means, not shown in the figures. These meshing means comprise, for example, an actuation system configured to determine the strikes to be executed as a function of the time displayed by the movement 3, in particular to act as minute repeaters or to signal a scheduled alarm time. Thus, when one or more strikes are to be sounded, the actuation system triggers the rotation of the hub 22.

[0057] The rotary device 20 is configured to bring the impactor into the release position 21 in front of the magnet 15. FIG. 3 shows one example wherein the impactor 21 is in the release position located the closest to the magnet 15. The magnet 15 has an opposite face 30 oriented towards the rotary device 20, such that the opposite face 30 of the magnet 15 and a contact face 31, 32, 33 of a movable impactor 16, 17, 18 are facing one another when the rotary device 20 is rotating. The opposite face 30 preferably has a substantially planar surface.

[0058] The attractive force of the magnet 15 and the distance between the contact face 31, 32, 33 of the movable impactor 16, 17, 18 in the release position and the opposite face 30 of the magnet 15 are chosen such that the magnet 15 attracts the impactor 16 against the opposite face 30 thereof, when it passes in front of the opposite face 30 thereof. Thus, the magnetic potential energy produced by the magnet 15 acting on the movable impactor 16, 17, 18 is transformed into kinetic energy by the movable impactor 16, 17, 18. This kinetic energy is transmitted to the hammer 8 through the impact of the movable impactor 16, 17, 18.

[0059] More specifically, when the movable impactor 16, 17, 18 is attracted by the magnet 15, it is accelerated and strikes the magnet 15. When the movable impactor 16, 17, 18 collides with the opposite face 30 of the magnet 15, at least a part of the momentum thereof is transmitted to the hammer 8 through the magnet 15, the hammer 8 being disposed against the front face 29 of the magnet in the rest position.

[0060] This principle of motion transmission combined with magnetic attraction is known as the “Gaussian cannon”. The attraction of the magnet 15 guarantees a minimum intensity for each strike of the hammer 8. The resulting strike is more consistent over the entire duration of the strike, independently of the barrel torque.

[0061] As shown in FIG. 4, each movable impactor 16, 17, 18 is configured to impact the magnet 15 in order to provide a pulse to the hammer.

[0062] Moreover, the movable impactors 16, 17, 18 and the rotary device 20 are configured such that the momentum transmitted to the hammer 8 by the impactor 16, 17, 18 is greater than the retaining force of the magnet acting on the hammer 8, such that the hammer detaches from the magnet 15 and strikes the resonant element 5 with sufficient force, as shown in FIG. 4.

[0063] As shown in FIG. 5, the magnet 15 and the hammer 8 are further configured so that the front face 29 attracts the hammer 8 against it, after it has struck the resonant element 5. Thus, the hammer 8 returns to the rest position 9 thereof, and can be actuated again by the next movable impactor 16, 17, 18. It further prevents the hammer 8 from rebounding and striking the resonant element 5 again in an unwanted manner.

[0064] In the case of a hammer 8 that does not include magnetically conductive material, the flexible guide 12 brings the hammer back against the magnet 15.

[0065] As it continues to rotate, the rotary device 20 pulls on the movable impactor 16, 17, 18 such that it detaches from the opposite face 30 of the magnet 15. At the same time, as the hub 22 rotates, the next movable impactor 16, 17, 18 approaches the magnet 15.

[0066] The rotation device 20 is actuated by the movement, when a stroke is required. Thus, the stroke sounds automatically thanks to the movable impactors 16, 17, 18, the magnet 15, the hammer 8 and the resonant element 5.

[0067] During operation, each movable impactor 16, 17, 18 impacts the magnet 15 one after the other, to produce a sound each time. With each impact of a movable impactor 16, 17, 18, the hammer 8 strikes the resonant element 5, and returns to its rest position 9 against the magnet 15 between two successive impacts.

[0068] Depending on the number of strokes to be emitted, the rotation device is actuated over a predefined period of time.

[0069] Preferably, the rotation is carried out at a constant speed so that the strokes are periodically emitted at the same frequency.

[0070] The rotational speed can also be variable so as to emit a particular stroke.

[0071] It goes without saying that the present invention is not limited to the example shown but that various alternatives and modifications that may be apparent to a person skilled in the art can be made thereto. In particular, the device can comprise a greater or lesser number of arms and impactors than those illustrated in the embodiment described.