Micromechanical device with thermal actuation, in particular for timepieces

Abstract

The invention relates to a thermally actuated micromechanical device (1), particularly for a clockwork movement, the micromechanical device (1) comprising a first mechanically actuable moving part (3), and a second mechanically actuable moving part (4), the second moving part (4) being translationally movable relative to the first moving part (3) between an engaged position, in which the first moving part (3) mechanically cooperates with the second moving part (4) to actuate it, and a rest position, in which the second moving part (4) cannot mechanically cooperate with the first moving part (3), the micromechanical device (1) comprising a support (5) on which the second moving part (4) is mounted, characterized in that the support (5) is thermally deformable to move the second moving part (4) from the rest position to the engaged position and / or vice versa.

Description

Technical field of the invention

[0001] The invention relates to the field of micromechanical devices that can be acted upon at a specific point, and more particularly to the field of thermally actuation micromechanical devices, especially for watchmaking. Technological background

[0002] In gear mechanisms, it may be necessary to use a micromechanical device that can be acted upon at specific points. More specifically in watchmaking, there are mechanisms for adjusting a particular clockwork module, such as the time or date, or for regulating the movement's rate.

[0003] These mechanisms are activated intermittently and create a mechanical link between gears.

[0004] To operate them, these mechanisms either require an actuation device accessible from outside the timepiece, such as a winding crown and a stem to set the time; or they require opening the case of the timepiece to reach the clock module, for example in the case of setting the rate.

[0005] Actuation from outside the case adds complexity to the movement, as components must be added to reach the actuating mechanism. Furthermore, the case must be watertight.

[0006] Opening the casing changes the pressure inside the casing, and has negative repercussions on the operation of the regulating organ.

[0007] There are micromechanical actuation devices that can be operated from outside the housing, without opening it. For example, document DE1720495 presents a magnetic actuation, while document CH504030 presents a thermal actuation, and document EP3118693 presents a light-based actuation.

[0008] However, these micromechanically actuated devices do not allow for sufficient adjustment precision. Summary of the invention

[0009] The aim of the present invention is to overcome all or part of the aforementioned drawbacks by proposing a micromechanical device for precise adjustment, which can be operated from outside a housing.

[0010] For this purpose, the invention relates to a thermally actuated micromechanical device, in particular for a clock movement, the micromechanical device comprising a first mechanically actuable moving part and a second mechanically actuable moving part, the second moving part being movable relative to the first moving part between an engaged position, in which the first moving part cooperates mechanically with the second moving part to actuate it, and a disengaged rest position, in which the second moving part cannot cooperate mechanically with the first moving part, the micromechanical device comprising a support on which the second moving part is mounted.

[0011] The invention is remarkable in that the support is thermally deformable to move the second moving part from the rest position to the engaged position and / or vice versa.

[0012] Thanks to the invention, we have a micromechanical device that allows two moving parts to be mechanically connected via thermal actuation. Thus, it does not require an additional mechanical mechanism to connect the two parts.

[0013] The device is simple to manufacture and allows for remote actuation by heating the support.

[0014] Furthermore, such a device can be operated from outside a case, for example in the case of a watch component where adjustments are needed without opening the case. Indeed, the micromechanical device can be operated by heating, while leaving the case closed.

[0015] According to a particular embodiment of the invention, the support comprises, at least in part, preferably in whole, a thermally deformable memory material, when it exceeds a threshold temperature.

[0016] According to a particular embodiment of the invention, the threshold temperature is between 60°C and 80°C, preferably between 65°C and 75°C, or even substantially equal to 70°C.

[0017] According to a particular embodiment of the invention, the support is a seesaw.

[0018] According to a particular embodiment of the invention, the rocker comprises a curved portion, the rocker straightening to move the second moving part from the rest position to the engaged position.

[0019] According to a particular embodiment of the invention, the second moving part is arranged in or near the curved portion of the rocker.

[0020] According to a particular embodiment of the invention, the micromechanical device comprises a shaft arranged perpendicularly to a first end of the rocker, to form a pivot around which the rocker can rotate.

[0021] According to a particular embodiment of the invention, the support comprises a pinion meshing with the second moving part.

[0022] According to a particular embodiment of the invention, the first moving part is a gear wheel.

[0023] According to a particular embodiment of the invention, the second moving part is a gear wheel.

[0024] According to a particular embodiment of the invention, the micromechanical device includes a return spring to push the second moving part back into the rest position.

[0025] The invention also relates to a clockwork movement, comprising such a micromechanical device.

[0026] According to a particular embodiment of the invention, the watch movement comprises a plate or a bridge provided with a housing for the support.

[0027] According to a particular embodiment of the invention, the housing includes a rim forming a support for a second end of the rocker.

[0028] The invention also relates to a timepiece comprising such a clockwork mechanism. Brief description of the figures

[0029] The aims, advantages and features of the present invention will become apparent from the reading of several embodiments given solely by way of non-limiting examples, with reference to the accompanying drawings in which: there figure 1 schematically represents a perspective view of part of a clockwork movement comprising a thermally actuated micromechanical device in a first configuration, the figure 2 schematically represents a perspective view of the part of the clockwork mechanism of the figure 1, in which the thermally actuated micromechanical device is in a second configuration, the figure 3 schematically represents a perspective view of part of a thermally actuated micromechanical device, the figure 4 schematically represents a top view of part of a thermally actuated micromechanical device, and the figure 5 schematically represents a perspective view of part of an adjustment mechanism driven by the micromechanical device according to the invention. Detailed description of the invention

[0030] THE figures 1 and 2 show a schematic representation of an embodiment of a thermally actuated device 1, intended to be arranged in a clock movement 10. The clock movement 10 includes a plate 11, and a housing 12 arranged in the plate 11 for the thermally actuated device 1.

[0031] The clockwork movement 10 further includes a main regulating wheel 2, the main regulating wheel 2 enabling the drive of a clockwork module mechanism.

[0032] The main moving part 2 is, for example, a date drive wheel. Such a wheel has a high gear ratio with the shaft, and allows for precise adjustment resolution.

[0033] The clockwork module includes, for example, a mechanism for regulating the rate of the clock movement, which is actuated by a cam 14 shown on the figure 5 Thus, the adjustment mechanism works when the main moving part 2 is actuated.

[0034] The thermally actuated device 1 further includes a first mechanical moving part 3, here a first gear wheel, and a second mechanical moving part 4, here a second mechanical moving part.

[0035] The first mechanical moving part 3 meshes with the main moving part 2 in order to be actuated. Thus, by rotating the main moving part 2, the first mechanical moving part 3 is rotated, thereby actuating the setting mechanism of the clockwork module associated with the first mechanical moving part 3.

[0036] The second mechanical mobile 4 is mobile relative to the first mechanical mobile 3 between an engaged position, in which the first mechanical mobile 3 meshes with the second mechanical mobile 4, and a rest position, in which the first mechanical mobile 3 does not mesh with the second mechanical mobile 4.

[0037] To this end, the second mechanical mobile 4 is mounted on a support 5, configured to be able to move the second mechanical mobile 4 from the rest position to the engaged position, and vice versa.

[0038] In this embodiment, the support 5 is a rocker of substantially longitudinal shape. The rocker comprises a curved portion 7, connecting two substantially straight portions. The rocker comprises two ends 9, 15.

[0039] Preferably, the second mechanical mobile 4 is arranged in the curved portion 7 of the rocker, which moves over a longer distance than the straight portions.

[0040] On the figure 3 The support 5 also includes a pinion 6 and shaft 8, arranged at a first end 9 of the rocker, the pinion 6 being mounted on the shaft 8. The shaft 8 is arranged through the plate 11 and through the support 5. Thus, the first end 9 of the rocker is held in the housing 12. However, the shaft 8 forms a pivot around which the rocker can rotate.

[0041] Pinion 6 meshes with the second mechanical component 4, regardless of its position. When the second mechanical component 4 is driven, pinion 6 actuates the shaft. The shaft 8 is connected to a gear system, not shown in the figures, which can be actuated, preferably intermittently, for example by the wearer of the timepiece containing this movement.

[0042] According to the invention, the support 5 is thermally deformable between two configurations. A first configuration in which the second mechanical moving part 4 is in the engaged position, and a second configuration in which the second mechanical moving part 4 is in the rest position, as shown in the figure 2 .

[0043] More specifically, the support 5 deforms thermally when it exceeds a threshold temperature. Preferably, the support 5 deforms in the engaged position when the threshold temperature is exceeded.

[0044] To this end, support 5 includes a shape-memory material. Such a material deforms above a threshold temperature and returns to its original shape below that threshold temperature.

[0045] Different types of shape memory materials are possible.

[0046] For example, a copper-based alloy with the following composition by weight can be used: Cu between 64.5 and 85%, Zn between 9.5 and 25% and Al between 4.5 and 10%, Cu between 79.5 and 84%, Al between 12.5 and 14% and Ni between 2.5 and 6%, Cu between 87 and 88%, Al between 11 and 12% and Be between 0.3 and 0.7%.

[0047] There are also gold-based alloys, such as 50Au40Ti10Zr, 52Au47Ti1Zr and 50Au45Ti3Zr2Nb, having for example the following composition, in atomic percentage: 46 to 55 at% gold, 38 to 47 at% titanium, 0.1 to 15 at% zirconium, 0 to 5 at% niobium.

[0048] Nickel and titanium alloys, such as Nitinol, or even plastic materials, can also be used as shape memory materials for the support.

[0049] Thus, in the event of a temperature change, beyond the threshold temperature, the rocker arm rights itself, and moves the second mechanical moving part 4 from its rest position to the engaged position so that it can be driven by the first mechanical moving part 3 and therefore by the main moving part 2. When the rocker arm deforms, the ends 9 and 15 of the rocker arm remain essentially in the same position. However, the curvature of the curved portion 7 of the rocker arm decreases.

[0050] The direction of movement of the curved portion 7 is directed towards the first mechanical moving part 4.

[0051] The housing 12 of the plate 11 includes a rim 13 that forms a support for the second end 15 of the rocker. The housing 12 is designed to allow deformation of the rocker. Here, the housing has a shape that widens from the rim 13 to the second end 15. The curved portion 7, and therefore the second mechanical moving part 4, moves within the housing 12 under the effect of the deformation.

[0052] When the temperature falls below the threshold temperature, the rocker returns to its original shape, with a more pronounced curvature. Thus, the second mechanical moving part 4 is once again separated from the first mechanical moving part 3, and can no longer be driven by it.

[0053] The threshold temperature is, for example, between 60°C and 80°C, preferably between 65°C and 75°C, or even approximately 70°C. Such a temperature range is high enough to prevent the material from deforming unintentionally, for example due to high ambient temperatures, and it is not too high to avoid the risk of damaging movement components, such as the oil.

[0054] Alternatively, the threshold temperature is chosen in negative temperatures, for example below -20°C.

[0055] Alternatively, the chosen material has two different threshold temperatures, a first threshold temperature to switch from the rest position to the engaged position, and a second threshold temperature to switch from the engaged position to the rest position.

[0056] To improve the transitions between positions, in particular to return to the rest position, the micromechanical device may include a return spring (not shown in the figures), in order to push the rocker and therefore the second mechanical moving part back into the rest position.

[0057] There figure 5 This shows a portion of the adjustment mechanism driven by the thermally actuated micromechanical device. A third gear 16 is mounted at the other end of the shaft 8 and meshes with a cam 17, which includes the cam 14. The cam 14 interacts with another part of the adjustment mechanism, not shown in the figure, comprising a feeler or a movable pawl, which allows, for example, the speed to be adjusted. Thus, the cam 4 is driven when the first gear 3 is in the engaged position.

[0058] In an alternative embodiment, not shown in the figures, the cam is replaced by a cam equipped with an eccentric. Such an eccentric is capable of cooperating with an adjustment mechanism that cooperates with said eccentric.

[0059] A clock movement equipped with such a micromechanical device 1 can be arranged in a clock part. For this purpose, the clock part comprises a case closed by a back.

[0060] The base is transparent, for example, to allow laser beams to pass through to the watch movement, specifically onto the micromechanical device's support. These laser beams are configured to heat the micromechanical device's support, causing it to deform.

[0061] Naturally, the invention is not limited to the embodiments of regulating organs described with reference to the figures, and variants could be envisaged without departing from the scope of the invention.

Claims

1. Micromechanical device (1) with thermal actuation, particularly for a clockwork movement, the micromechanical device (1) comprising a first mechanically actuable moving part (3), and a second mechanically actuable moving part (4), the second moving part (4) being translationally movable relative to the first moving part (3) between an engaged position, in which the first moving part (3) mechanically cooperates with the second moving part (4) to actuate it, and a rest position, in which the second moving part (4) cannot mechanically cooperate with the first moving part (3), the micromechanical device (1) comprising a support (5) on which the second moving part (4) is mounted, characterized in that the support (5) is thermally deformable to move the second moving part (4) from the rest position to the engaged position and / or vice versa.

2. Micromechanical device according to claim 1, characterized in thatthe support (5) comprises at least in part, preferably in whole, a thermally deformable memory material when it exceeds a threshold temperature.

3. Micromechanical device according to claim 2, characterized in that The threshold temperature is between 60°C and 80°C, preferably between 65°C and 75°C, or even approximately equal to 70°C.

4. A micromechanical device according to any one of the preceding claims, characterized in that the support (5) is a rocker.

5. Micromechanical device according to claim 4, characterized in that the rocker includes a curved portion (7), the rocker straightening to move the second moving part (4) from the rest position to the engaged position.

6. Micromechanical device according to claim 5, characterized in that the second mobile (4) is arranged in or in the immediate vicinity of the curved portion (7) of the rocker.

7. Micromechanical device according to any one of claims 4 to 6, characterized in that the micromechanical device (1) includes a shaft (8) arranged perpendicularly to a first end (9) of the rocker, to form a pivot around which the rocker can rotate.

8. A micromechanical device according to any one of the preceding claims, characterized in that the support (5) includes a pinion (6) meshing with the second moving part (4).

9. A micromechanical device according to any one of the preceding claims, characterized in that the first moving part (3) and the second moving part (4) are gear wheels.

10. Micromechanical device according to any one of the preceding claims, characterized in that It includes a return spring to push the second moving part (4) back into the rest position.

11. Clockwork movement, characterized in thatit includes a micromechanical device (1) according to any one of the preceding claims.

12. Clockwork movement according to claim 11, characterized in that it includes a plate (11) or a bridge provided with a housing (12) for the support (5).

13. Clockwork movement according to claim 12, dependent on claim 4, characterized in that the housing (12) includes a rim (13) forming a support for a second end (15) of the rocker.

14. Timepiece comprising a timepiece movement according to any one of claims 11 to 13.

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