Chiming mechanism by impact, in particular for timepieces

Abstract

The invention relates to a striking mechanism (1), particularly for a clockwork movement (3), the mechanism (1) comprising at least one resonant element (5) capable of emitting a sound when struck, and a hammer (8) movable between a rest position (9) and a striking position (11) in which it strikes the resonant element (5) to cause it to vibrate, characterized in that it comprises a hammer actuation system (8) comprising a movable striker (16, 17, 18) configured to move from a firing position (19) to a striking position (21) in which it transmits at least part of its momentum to the hammer (8) in order to move it from its rest position (9) to its striking position (11) to cause the resonant element (5) to vibrate. The invention also relates to a clockwork movement (3) comprising such a striking mechanism (1).

Description

Technical field of the invention

[0001] The invention relates to a percussion striking mechanism, particularly for watchmaking.

[0002] The invention also relates to a clockwork movement comprising such a striking mechanism. Technological background

[0003] In the field of watchmaking, a striking mechanism can be combined with a traditional watch movement to serve in particular as a minute repeater or to signal a programmed alarm time. Such a striking mechanism generally comprises at least one gong made of sapphire, quartz or a metallic material, such as steel, bronze, precious metal or metallic glass. This gong can describe for example at least a portion of a circle around the watch movement in the watch cage. The gong is fixed by at least one of its ends to a gong holder, which is itself integral with a watch plate. A hammer of the mechanism is rotatably mounted on the plate for example near the gong holder so as to strike the gong to make it vibrate. The sound produced by the gong struck by the hammer is notably in the audible frequency range of 1 kHz to 20 kHz.This allows the wearer of the watch to be notified of a specific time, a programmed alarm or a minute repeater.

[0004] As shown in patent document EP 1 574 917 A1, the striking mechanism of a watch may comprise two or more gongs fixed by one of their ends to a single gong-carrier, which is itself secured to a plate. Each gong may be struck by a respective hammer. To do this, each hammer is driven by its own drive spring, which must have been previously wound, so as to drive the hammer against the gong, in order to signal a minute repeater or an alarm time. Two damping counter-springs are each provided to push back and keep the two hammers away from the gongs in a rest mode. In a striking mode, the damping counter-springs act with a significant force and slow the fall of each hammer before striking the respective gong. These counter-springs allow each hammer to be pushed back to their rest position following the strike.Eccentrics are also provided for adjusting the operation of the countersprings to essentially prevent any rebound of each hammer against the respective gong.

[0005] A disadvantage of such a structure of the striking mechanism with these countersprings is that there is a significant loss of kinetic energy of the hammer when striking the respective gong, which reduces the acoustic level of the strike. This loss of energy is due largely to the slowdown imposed by each counterspring on the path of the hammer when it strikes the gong. Moreover, even if the pre-winding of the drive springs is increased, this implies an adaptation of the countersprings via their eccentric to also avoid any rebound, which is another disadvantage of such a striking mechanism.

[0006] Document WO2012151710A1 relates to a timepiece equipped with a sound mechanism, such as a minute repeater mechanism, the sound level of which is particularly high. This timepiece comprises: a housing comprising a sealed part and a non-sealed part, a striking mechanism arranged in the sealed part of the housing, at least one gong intended to be actuated by the striking mechanism and located entirely in the non-sealed part of the housing.

[0007] The wall of the case does not include a membrane or holes. A hammer is equipped with a magnet or electromagnet and the gong designed to cooperate with this hammer is equipped with a magnet or electromagnet, so that the movements of the hammer are transmitted electromagnetically to the corresponding gong. Concretely, if a magnet or electromagnet is placed at the end of the hammer, when it makes its back and forth movement, it approaches, then repels (if the polarities are reversed), another magnet or electromagnet fixed on the gong. The information on the movements is thus transmitted from one side of the wall to the other without it being necessary to provide a membrane or a striker. Summary of the invention

[0008] The invention therefore aims to overcome the drawbacks of the aforementioned state of the art by providing a striking mechanism for a timepiece, with the aim of avoiding a significant loss of energy when the hammer falls against the gong.

[0009] To this end, the invention relates to a striking mechanism, in particular for watchmaking, the mechanism comprising at least one resonant element making it possible to emit a sound when struck, and a hammer movable between a rest position and a shock position in which it strikes the resonant element to make it vibrate.

[0010] The striking mechanism comprises a hammer actuation system comprising a movable striker configured to move from a trigger position to a percussion position, in which it transmits to the hammer a quantity of movement in order to move it from its rest position to its shock position to vibrate the resonating element.

[0011] The striking mechanism according to the invention as claimed is remarkable in that it comprises a magnet fixed relative to the clockwork movement, the magnet being configured to attract the movable striker in the percussion position.

[0012] Thus, the momentum provided by a striker is used to drive the hammer. Thanks to the momentum of the striker, the hammer receives enough energy to strike the gong and make it vibrate. In addition, by selecting a specific mass difference between the hammer and the striker, the speed of the hammer can be adjusted. For example, a hammer with a reduced mass can be chosen, which moves to strike the gong with a greater speed than the striker with a greater mass.

[0013] This striking mechanism saves the energy required to operate the hammer. In addition, a lighter, faster-moving hammer reduces the risk of rebound after striking the gong.

[0014] According to a particular embodiment of the invention, the hammer comprises a magnetically conductive material.

[0015] According to a particular embodiment of the invention, the striker comprises a magnetically conductive material, so as to be attracted by the magnet.

[0016] According to a particular embodiment of the invention, the hammer is in contact with the magnet in its rest position.

[0017] According to a particular embodiment of the invention, the striker is configured to strike the magnet so as to give an impulse to the hammer.

[0018] According to a particular embodiment of the invention, the distance between the firing position of the striker and the magnet is chosen so that the magnet attracts the striker against it in its percussion position.

[0019] According to a particular embodiment of the invention, the momentum transmitted by the striker is sufficiently large to overcome the retaining force of the magnet acting on the hammer, so that the hammer detaches from the magnet and strikes the resonant element.

[0020] According to a particular embodiment of the invention, the mechanism comprises a flexible guide on which the hammer is mounted to allow it to move between its rest position and its impact position.

[0021] According to a particular embodiment of the invention, the flexible guide is configured to press the hammer against the magnet.

[0022] According to a particular embodiment of the invention, the actuation system comprises a flexible guide on which the striker is mounted to allow it to move between the trigger position and the percussion position.

[0023] According to a particular embodiment of the invention, the flexible guide comprises a flexible blade or a flexible neck.

[0024] According to a particular embodiment of the invention, the actuation system comprises a rotary device provided with the striker, the rotary device being configured to bring the striker into the trigger position.

[0025] According to a particular embodiment of the invention, the actuation system comprises at least one additional striker, preferably two additional strikers, arranged on the rotary device, so as to alternately bring each striker into the trigger position.

[0026] According to a particular embodiment of the invention, the rotating device comprises a rotating hub.

[0027] According to a particular embodiment of the invention, the rotary device comprises at least one arm, each arm carrying a striker.

[0028] According to a particular embodiment of the invention, the rotary device comprises several arms distributed angularly around the hub.

[0029] According to a particular embodiment of the invention, the mass of the striker is greater than that of the hammer, for example, the mass of the striker is at least twice as great as that of the hammer.

[0030] The invention also relates to a clockwork movement comprising such a striking mechanism. Brief description of the figures

[0031] Other features and advantages will become clear from the description given below, for information purposes only and in no way limiting, with reference to the attached drawings, in which: there figure 1is a schematic representation of a timepiece comprising a percussion striking mechanism according to one embodiment of the invention; the figure 2 is an enlarged schematic representation of the striking mechanism of the figure 1 ; there figure 3 is a schematic representation of the striking mechanism of the figure 1 , in which the firing pin is in the firing position; the figure 4 is a schematic representation of the striking mechanism of the figure 1 , in which the striker is in the percussion position with the magnet and the hammer is in the shock position with the gong; and the Figure 5 is a schematic representation of the striking mechanism of the figure 1 , in which the firing pin is no longer in the percussion position or in the trigger position and the hammer has returned to the rest position. Detailed description of the invention

[0032] As explained above, the invention relates to a percussion striking mechanism 1. The striking mechanism 1 is intended for a timepiece 10, such as a watch shown in the figure 1 . The timepiece 10 comprises a caseband 2 and a watch movement 3, preferably mechanical, which is for example provided with a plate 4 and a barrel spring to provide the operating energy. The embodiment described below is based on the combination of the “Gauss magnetic gun” principle and the principle of conservation of momentum during an impact.

[0033] On the figures 1 to 5, the striking mechanism 1 comprises a resonant element 5, for example a gong conventionally used in clockwork strikes. The resonant element 5 makes it possible to emit a sound 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 next to the plate 4, for example in a plane parallel to that of the plate.

[0034] Other configurations of resonant element 5 are possible. The resonant element 5 may further comprise a circular portion 7, shown in the figure 1 , in particular to run along the inner face of the middle 2.

[0035] To emit a sound, the mechanism 1 comprises a movable hammer 8 relative to the plate 4. The hammer 8 is movable between two positions, a rest position 9 distant from the resonant element 5, and a shock position 11 in which it strikes the resonant element to make it vibrate. Thus, the resonant element 5 produces a vibration which propagates in the watch. The external part of the watch radiates these vibrations so as to emit a sound. Other embodiments are possible with various shapes of hammer 8 and resonant element 5.

[0036] The mechanism 1 here comprises a flexible guide 12 on which the hammer 8 is mounted to allow it to move between its rest position 9 and its impact position 11. The flexible guide 12 preferably comprises a first flexible blade 13 assembled to the plate 4 on the one hand, and to the hammer 8 on the other hand. The first flexible blade 13 is preferably arranged substantially parallel to the resonant element 5 when the hammer 8 is in the rest position 9. By the elastic deformation of the first flexible blade 13, the hammer 8 passes from the rest position 9 to the impact position 11 and vice versa.

[0037] According to the invention as claimed, the mechanism 1 further comprises a magnet 15 fixed relative to the plate 4. The magnet 15 is preferably assembled on the plate 4. The magnet 15 is for example arranged on a promontory 14 opposite the resonant element 5.

[0038] Preferably, the magnet 15 is configured to retain the hammer 8 in its rest position 9. For this purpose, the hammer 8 comprises a magnetically conductive material, which induces an attractive force of the hammer 8 against the magnet 15.

[0039] Alternatively, a hammer 8 may be chosen that does not comprise a magnetically conductive material. In this case, the flexible guide 12 is configured to apply a prestress to the hammer 8, so as to press it against the magnet 8.

[0040] Thus, in the rest position 9, the hammer 8 is in contact with a front face 29 of the magnet 15. The hammer 8 keeps this position permanently, except 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.

[0041] The front face 29 preferably has a substantially flat 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.

[0042] According to the invention, the mechanism 1 comprises a system for actuating the hammer 8. This mechanism is configured to cause the movement of the hammer 8 from its rest position 9 to its impact position 11. In particular, it serves to separate the hammer 8 from the magnet 15 and allow it to reach the resonant element 5.

[0043] To this end, the actuation system 20 comprises at least one movable striker 16, 17, 18 configured to transmit to the hammer 8 a sufficient quantity of movement for it to move from its rest position 9 to its impact position 11 and to vibrate the resonant element 5.

[0044] The striker 16, 17, 18 is configured to move from a trigger position 19 to a percussion position 21 in which it transmits a quantity of movement to the hammer 8.

[0045] In, the embodiment of the figures 1 to 5 , the actuation system comprises a rotary device 20 provided with three movable strikers 16, 17, 18.

[0046] The rotary device 20 comprises a hub 22 and three arms 23, 24, 25, distributed angularly around the hub 22, and are connected to the hub 22 by one end. Each arm 23, 24, 25 carries a movable striker 16, 17, 18 arranged 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 also preferably passes through the magnet 15, the hammer 8 and the resonant element 5.

[0047] Each movable striker 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 between 30 and 60°, when the movable striker 16, 17, 18 is in the trigger position 19, and the angle is between 60 and 90°, when the movable striker 16, 17, 18 is in the percussion position 21. An arm can, for example, be an oblong body, a gear tooth or a plate.

[0048] Preferably, each movable striker 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 move from the trigger position 19 to the percussion position 21. The flexible guide here comprises a second flexible blade 26 assembled to the movable striker 16, 17, 18 on the one hand, and on the other hand to the end of the arm 23, 24, 25.

[0049] Each movable striker 16, 17, 18 comprises a contact face 31, 32, 33, which is intended to come into contact with the magnet 15, when it passes from the trigger position 19 to the percussion position 21. The contact faces 31, 32, 33 of the movable striker 16, 17, 18 are preferably rounded, to allow easier detachment when the movable striker 16, 17, 18 returns to its trigger position.

[0050] When the rotary device 20 rotates, it positions one of the movable strikers 16, 17, 18 opposite the magnet 15. The movable striker 16, 17, 18 then moves from the trigger position 19 to the percussion position 21 according to a radial displacement. Once the percussion has been carried out, the rotary device 20 continues to rotate in order to prevent the movable striker 16, 17, 18 from remaining against the magnet 15. The geometry of the movable strikers 16, 17, 18 is produced so as to require the least possible torque on the rotary device 20. For example, a contact face 32 is chosen having a ramp shape tangential to the rotary movement.

[0051] The rotary device 20 is actuated by rotating the hub 22 around its axis, so that the arms 23, 24, 25 rotate around the axis of the hub 22. Thus, the movable strikers 16, 17, 18 also rotate around the axis of the hub 22 while remaining in the trigger position 19. In other words, the movable strikers 16, 17, 18 remain in the same position relative to the arms 23, 24, 25, which carry them.

[0052] To rotate, the means 22 is mechanically connected to the barrel of the movement by means of gear means, not shown in the figures. These gear means comprise for example an actuation system configured to determine the strikes to be executed according to the time displayed by the movement 3, to serve in particular as minute repeaters or to signal a programmed alarm time. Thus, when one or more strikes are to sound, the actuation system triggers the rotation of the hub 22.

[0053] The rotary device 20 is configured to bring the striker into the trigger position 21 in front of the magnet 15. The figure 3 shows an example in which the striker 21 is in the trigger position closest to the magnet 15. The magnet 15 has an opposite face 30 oriented towards the rotating device 20, so that the opposite face 30 of the magnet 15 and a contact face 31, 32, 33 of a movable striker 16, 17, 18 are opposite each other when the rotating device 20 rotates. The opposite face 30 preferably has a substantially flat surface.

[0054] The attractive force of the magnet 15 and the distance between the contact face 31, 32, 33 of the movable striker 16, 17, 18 in the trigger position and the opposite face 30 of the magnet 15 are chosen so that the magnet 15 attracts the striker 16 against its opposite face 30, when it passes in front of its opposite face 30. Thus, the magnetic potential energy produced by the magnet 15 acting on the movable striker 16, 17, 18 is transformed into kinetic energy by the movable striker 16, 17, 18. This kinetic energy is transmitted to the hammer 8 by the impact of the movable striker 16, 17, 18.

[0055] Indeed, when the movable striker 16, 17, 18 is attracted by the magnet 15, it is accelerated and strikes the magnet 15. When the movable striker 16, 17, 18 collides with the opposite face 30 of the magnet 15, at least part of its momentum is transmitted to the hammer 8 through the magnet 15, the hammer 8 being arranged against the front face 29 of the magnet in the rest position.

[0056] This principle of motion transmission combined with magnetic attraction is known as the "Gauss cannon". The attraction of magnet 15 guarantees a minimum intensity with each strike of hammer 8. The resulting strike is more constant throughout the duration of the strike, regardless of the barrel torque.

[0057] As shown in the figure 4 , each movable striker 16, 17, 18 is configured to strike the magnet 15 so as to give an impulse to the hammer.

[0058] Furthermore, the movable strikers 16, 17, 18 and the rotating device 20 are configured so that the amount of movement transmitted to the hammer 8 by the striker 16, 17, 18 is greater than the retaining force of the magnet acting on the hammer 8, so that the hammer detaches from the magnet 15 and strikes the resonant element 5 with sufficient force, as shown in figure 4 .

[0059] As shown on the Figure 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 its rest position 9, and can be actuated again by the following movable striker 16, 17, 18. This also prevents the hammer 8 from bouncing and striking the resonant element 5 again in an inopportune manner.

[0060] In the case of a hammer 8 not comprising magnetically conductive material, the flexible guide 12 brings the hammer back against the magnet 15.

[0061] By continuing to rotate, the rotation device 20 pulls on the movable striker 16, 17, 18 so that it detaches from the opposite face 30 of the magnet 15. At the same time, as the hub 22 rotates, the next movable striker 16, 17, 18 moves closer to the magnet 15.

[0062] The rotating device 20 is actuated by the movement, when a ringing is required. Thus, the ringing sounds automatically thanks to the movable strikers 16, 17, 18, the magnet 15, the hammer 8 and the resonant element 5.

[0063] In operation, each movable striker 16, 17, 18 strikes the magnet 15 one after the other, to produce a sound each time. With each percussion of a movable striker 16, 17, 18, the hammer 8 strikes the resonant element 5, and returns to the rest position 9 against the magnet 15 between two successive percussions.

[0064] Depending on the number of rings to be emitted, the rotating device is activated for a predefined time.

[0065] Preferably, the rotation is carried out at a constant speed so that the ringing strokes are emitted periodically at the same frequency.

[0066] The rotation speed can also be varied to emit a particular ringing sound.

[0067] Of course, the present invention is not limited to the illustrated example but is susceptible to various variants and modifications within the scope of the subject of the appended claim 1. In particular, the device may comprise a greater or lesser number of arms and strikers than those illustrated in the described embodiment.

Claims

1. 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, the striking mechanism (1) comprising 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, characterised in that it includes 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).

2. Striking mechanism according to claim 1, characterised in that the hammer (8) is in contact with the magnet (15) in the rest position (9) thereof.

3. Striking mechanism according to claim 2, characterised in that 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).

4. Striking mechanism according to claim 3, characterised in that 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) against it in the impact position (21) thereof.

5. Striking mechanism according to claim 3 or 4, characterised in that 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).

6. Striking mechanism according to any one of the preceding claims, characterised in that It 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.

7. Striking mechanism according to any one of the preceding claims, characterised in that the actuation system comprises a flexible guide on which the movable impactor (16, 17, 18) is mounted to enable it to move between the release position (19) and the impact position (21).

8. Striking mechanism according to claim 6 or 7, characterised in that the flexible guide (12) includes a flexible strip (13, 26, 27, 28) or a flexible neck.

9. Striking mechanism according to any one of the preceding claims, characterised in that 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).

10. Striking mechanism according to claim 9, characterised in that the actuation system comprises at least one additional impactor (16, 17, 18), preferably two additional impactors, arranged on the rotary device (20), so as to alternately bring each movable impactor (16, 17, 18) into the release position (19).

11. Striking mechanism according to any one of the preceding claims, characterised in that the rotary device (20) comprises a hub (22).

12. Striking mechanism according to claim 9, characterised in that 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).

13. Striking mechanism according to claim 9, characterised in that the rotary device (20) comprises a plurality of arms (22, 23, 24) angularly distributed around the hub (22).

14. Horological movement (3), characterised in that it comprises a striking mechanism (1) according to any one of the preceding claims.

Images