Timepiece mobile with reduced inertia, in particular for an escapement mechanism

Abstract

One aspect of the invention relates to a clockwork mechanism (20, 30), in particular for an escapement mechanism (50), the mechanism (20, 30) comprising a central hub (2) and a circular peripheral toothing (14), the hub (2) being arranged inside the peripheral toothing (14), substantially in the same principal plane, the mechanism (20, 30) comprising a first series of blades (5, 15) connecting the hub (2) to the peripheral toothing (4), the blades (5, 15) being distributed around the hub (2) in the principal plane, in which the blades (5, 15) are arranged substantially tangentially to the circumference of the hub (2), the direction of the blades (5) forming an angle between -20° and +20° with the tangent to the hub (2), preferably between -10° and +10°, or even between -5° and +5°.

Description

Technical field of the invention

[0001] The present invention relates to a clockwork mechanism with reduced inertia, particularly for an escapement mechanism. Technological background

[0002] In most mechanical watches, the energy needed to rotate the hands (e.g., minute and hour indicator hands) is stored in a barrel and then released by a balance-spring system, which includes a flywheel called a balance wheel, associated with a spring in the form of a spirally wound ribbon, called a balance spring.

[0003] At one internal end, the spiral is fixed to a shaft that is rotating with the balance wheel; at one external end, the spiral is fixed to a stud mounted on a stud holder which is itself fixed to a bridge (or cock).

[0004] The balance wheel's rotation is maintained—and its oscillations counted—by an escapement mechanism comprising an anchor with a low-amplitude oscillating motion, equipped with two or three pallets that engage the teeth of an escape wheel. Thus engaged, the escape wheel is imparted a step-by-step rotational motion whose frequency is determined by the anchor's oscillation frequency, itself synchronized with the balance wheel's oscillation frequency.

[0005] With a traditional escapement mechanism, the oscillation frequency is approximately 4 Hz, or about 28,800 vibrations per hour (A / h). One objective of skilled watchmakers is to ensure the isochronism and regularity of the oscillations (or constant rate) of the balance wheel and hairspring.

[0006] Today, the balance spring can be replaced by a flexible guide as the spring element to form a virtual pivot. Flexible guides with a virtual pivot significantly improve watch resonators. The simplest are crossed-leaf pivots, composed of two straight-leaf guide devices that intersect. These two leaves can be either three-dimensional in two different planes or two-dimensional in the same plane, in which case they are essentially welded at their point of intersection. However, there are also uncrossed-leaf guides of the RCC (Remote Center Compliance) type, which have straight leaves that do not intersect. Such a resonator is described in documents EP14199039 and EP16155039.

[0007] However, such a flexible guide must have a certain rigidity to properly guide the resonator, so the balance wheel has a much smaller amplitude, with a rotation angle of 10° to 40°, whereas with a balance spring the rotation angle is 330°. Furthermore, the balance wheel oscillates at a much higher frequency than one mounted on a balance spring.

[0008] Because the oscillation amplitude is reduced and the frequency increased, new escapement mechanism configurations have been invented to operate with a flexible-guided regulating organ. For example, patents CH710524 and CH713150 describe specific escapement mechanisms for flexible guides.

[0009] However, these escapement mechanisms tend to be inefficient and prone to stopping upon impact. Furthermore, their size is still too great for easy integration into a watch movement.

[0010] The low efficiency of escapement mechanisms used with a flexible-guided resonator stems in particular from losses due to the fact that the finishing gear, escape wheel and anchor must be set in motion and then stopped a number of times equivalent to twice the oscillation frequency every second.

[0011] Thus, the inertia of the anchor, the escape wheel and the moving parts of the finishing gear close to the escape wheel, is crucial to obtain an acceptable efficiency. Summary of the invention

[0012] One aim of the present invention is to provide a new type of moving part, which in particular allows a traditional escapement mechanism to operate, with good efficiency, with a regulating element provided with a flexible guide.

[0013] To this end, the invention relates to a clockwork mechanism, in particular for an escapement mechanism, the mechanism comprising a central hub and a circular peripheral toothing, the hub being arranged inside the peripheral toothing substantially in the same principal plane, the mechanism comprising a first series of blades connecting the hub to the peripheral toothing, the blades being distributed around the hub in the principal plane.

[0014] The invention is remarkable in that the blades are arranged substantially tangentially to the circumference of the hub, the direction of the blades forming an angle between -20° and +20° with the tangent to the hub, preferably between -10° and +10°, or even between -5° and +5°.

[0015] This blade arrangement improves the rigidity of the moving part, particularly by preventing the risk of blade buckling when the moving part meshes with another moving part in a gear system. It also avoids the need for a large number of blades, as on an old spoked bicycle wheel where the spokes were arranged radially on the hub.

[0016] Indeed, by choosing an appropriate direction of rotation, the blades essentially undergo longitudinal tensile stress, and reduce shear stress.

[0017] Thanks to the invention, the inertia of the moving part is significantly reduced, because the blades are much lighter and thinner than the arms that usually connect the hub to the peripheral teeth in a classic clockwork moving part.

[0018] According to a particular embodiment of the invention, the clockwork mechanism has a rotational inertia of less than 5mg.mm 2<, preferably less than 3mg.mm 2<, or even less than 2mg.mm 2<.

[0019] According to a particular embodiment of the invention, the thickness of a blade follows the following equation: e ≤ h 3 , preferably e e ≤ h 5 , Or h is the height of the blade.

[0020] According to a particular embodiment of the invention, each blade of the first series is arranged in a direction making an angle with the direction of the preceding blade, in which the angle α = 2 π N , Or N is the number of blades in the first series

[0021] According to a particular embodiment of the invention, the blades of the first series are distributed uniformly around the hub.

[0022] According to a particular embodiment of the invention, the blades are straight.

[0023] According to a particular embodiment of the invention, the clockwork mechanism comprises a second series of blades connecting the hub to the peripheral teeth in the main plane, so as to form a network of blades intersecting with the first series of blades.

[0024] According to a particular embodiment of the invention, the blades of the second series are arranged substantially tangentially to the circumference of the hub.

[0025] According to a particular embodiment of the invention, the network forms a star-shaped structure.

[0026] According to a particular embodiment of the invention, the blades of the second series are curved.

[0027] According to a particular embodiment of the invention, the peripheral teeth comprise teeth, each tooth being arranged at the junction of the free ends of a blade of the first series and a blade of the second series.

[0028] According to a particular embodiment of the invention, the peripheral teeth comprise an annular rim provided with teeth.

[0029] According to a particular embodiment of the invention, the annular rim is hollowed out.

[0030] The invention also relates to an escapement mechanism comprising an anchor and such a clockwork mobile with reduced inertia as an escape wheel, the escapement mechanism being configured to cooperate with a regulating organ of a clockwork movement.

[0031] According to a particular embodiment of the invention, the regulating member comprises a flexible guide.

[0032] According to a particular embodiment of the invention, the escapement mechanism includes a second clockwork wheel with reduced inertia, such as an intermediate wheel between the seconds wheel and the escape wheel, the second clockwork wheel meshing with the first clockwork wheel.

[0033] The invention also relates to a clockwork movement comprising such an escapement mechanism. Brief description of the figures

[0034] Other features and advantages of the invention will become more apparent upon reading the following description of a particular embodiment of the invention, given by way of simple illustrative and non-limiting example, and the accompanying figures, among which: there figure 1 schematically represents a top view of a clockwork mechanism, according to a first embodiment of the invention; the figure 2schematically represents a top view of a clockwork mechanism, according to a second embodiment of the invention; the figure 3 schematically represents a perspective view of the second embodiment of the clockwork mechanism of the figure 2 ; there figure 4 schematically represents a top view of a variant of the second embodiment of the clockwork mobile of the figure 2 ; there figure 5 schematically represents a top view of a clockwork mechanism, according to a third embodiment of the invention; the figure 6 schematically represents a top view of an escapement mechanism comprising a clockwork wheel according to the third embodiment of the invention, the figure 7 schematically represents an enlarged top view of part of the escapement mechanism of the figure 6 , there figure 8schematically represents a top view of an escapement mechanism comprising two clockwork components according to the invention, the figure 9 schematically represents a top view of a regulating organ associated with the escapement mechanism of the figure 8 , and the Figure 10 schematically represents a cross-sectional view of the regulating organ associated with the escapement mechanism of the figure 9 without flexible guidance. Detailed description of the invention

[0035] THE figures 1 to 5 represent different modes of realization of clockwork mobiles 1, 10, 20, 30, in particular for an escapement mechanism 50.

[0036] Each clockwork mobile 1, 10, 20, 30 comprises a hub 2 and a peripheral toothing 4. The hub 2 is arranged inside the peripheral toothing 4, preferably substantially in the same principal plane.

[0037] On the figures 1 to 3, the peripheral teeth 4 comprise an annular rim 9, 19 provided with teeth 8, 18, while in the embodiment of the figure 4 The peripheral teeth 14 comprise a rim 19 and hollow teeth 18. The peripheral teeth 4 comprise two superimposed sinusoids.

[0038] In these embodiments, the clockwork mechanism 1, 10, 20, 30 also includes a shaft 7 and a pinion 3, the shaft 7 being arranged through the hub 2 and the pinion 3 being mounted on the shaft 7 above the hub 2.

[0039] On the figure 1 , the clockwork mechanism 1 includes a first series of blades 5 connecting the hub 2 to the peripheral teeth 4.

[0040] The blades 5 of the first series are evenly distributed around the hub 2 in the principal plane. Preferably, the blades 5 of the first series are straight. Alternatively, the blades 5 of the first series are curved.

[0041] According to the invention, the blades 5 of the first series are arranged in a direction substantially tangential to the hub 2. For example, the direction of the blades 5 forms an angle between -20° and +20° with the tangent, preferably between -10° and +10°, or even between -5° and +5°.

[0042] The blades 5 of the first series are arranged in a direction making an angle with the direction of the preceding or following blade 5, in which the angle α = ± 2 π N , Or N is the number of blades 5 in the first series. For example, on the figure 1 The clockwork mechanism 1 comprises ten blades 5. Each blade 5 is arranged in a direction making an angle of 36° with the direction of the next blade 5 or the direction of the preceding blade 5. The blades 5 are distributed in a clockwise direction.

[0043] In the modes of embodiment of figures 2 to 5, the clockwork mobiles 10, 20 include a second series of blades 6 connecting the hub 2 to the peripheral teeth 4 in the main plane.

[0044] The blades 6 of the second series are arranged in the same principal plane. Thus, blades 5, 6 of the first series and the second series form a network of intersecting blades.

[0045] In the method of implementation of figures 2, 3 and 4 , the blades 6 of the second series are arranged substantially tangentially to the hub 3, like the blades 5 of the first series, the characteristics being the same, but arranged in the counter-clockwise direction.

[0046] A blade 5 from the first series and a blade 6 from the second series join in pairs at the peripheral teeth 4. Thus, a star-shaped network of blades 5, 6 is obtained.

[0047] There figure 5shows another clockwork mechanism 30, which is more specifically suited to an escapement mechanism 50, such as the one shown on the figures 6 to 8 .

[0048] In this embodiment, the clockwork mechanism 30 also includes a hub 3 and two sets of blades 5, 16, but the peripheral teeth 24 do not have an annular rim. The peripheral teeth 24 include a tooth arranged at the junction of the free ends of a blade 5 from the first set and a blade 16 from the second set. Furthermore, the blades 16 of the second set are curved.

[0049] Preferably, to minimize the inertia of the moving parts 1, 10, 20, 30, the thickness of each blade 5, 6, 16 follows the following equation: e e ≤ h 3 , Or h is the height of the blade, preferably e ≤ h 5 .

[0050] Thanks to these configurations and parameters, the watch movements have a rotational inertia of less than 5 mg.mm 2<, preferably less than 3 mg.mm 2<, or even less than 2 mg.mm 2<.

[0051] Preferably, the watch movements 1, 10, 20, 30 are made of the same material, and are obtained by a deep photolithography process, of the UV-LIGA or DRIE type, in materials such as NiP or silicon.

[0052] These reduced inertia mobiles are used for example in escapement mechanisms of watch movements.

[0053] On the figures 6 to 8 The escapement mechanism 50 includes a first horological element 30 according to the configuration of the figure 5 as a mobile escapement, as well as an anchor 21.

[0054] The anchor 21 is equipped with two arms 11, 12, the ends of which form two pallets cooperating with the teeth 18 of the first clockwork mobile 30.

[0055] The arms 11, 12 of the anchor 21 cooperate with the first clockwork mobile 30 with reduced inertia, and interact alternately with the teeth 18 of the first clockwork mobile 30 to regulate the rate.

[0056] The anchor 21 also includes a longitudinal part 14 extending laterally and is provided with a fork 22 at its end to cooperate with an ellipse 23 of an inertial element 26.

[0057] To further reduce inertia and improve the response of the escapement mechanism 50, the latter also includes a second clockwork mechanism 20, the second clockwork mechanism 20 meshing with the first clockwork mechanism 30, like a seconds mechanism. The second clockwork mechanism 20 here corresponds to the embodiment of the figure 4 .

[0058] The teeth 14 of the second clockwork mechanism 20 mesh with the pinion 3 of the first clockwork mechanism 30.

[0059] On the Figures 9 and 10, such a reduced inertia escapement mechanism 50 is associated with a regulating organ 60. The regulating organ 60 includes a balance wheel 35, elastic return means 32 for the balance wheel 35.

[0060] The balance wheel 35 has a bone-like shape with a longitudinal portion 36 and a lateral portion 37 in the form of an arc of a circle at each end of the longitudinal portion 36. The balance wheel 35 further includes stops concentric to the virtual axis of rotation mounted in the middle of the longitudinal portion 36 and adjustment screws 39 for the inertia of the balance wheel arranged in the lateral portions 37.

[0061] The balance wheel 35 is mounted on elastic return means 5 to enable it to perform a rotary oscillatory motion around a virtual center of rotation. The elastic return means 32 are directly connected to the balance wheel 35.

[0062] The elastic return means 32 include a system of flexible blades 37, here two pairs of crossed flexible blades 37, arranged in series, and forming a double pivot to improve the angle of rotation of the rocker 35.

[0063] An ellipse 23 extends under the balance wheel 35 from the longitudinal portion 36 to cooperate with the fork 22 of the anchor 21. The ellipse is mounted integrally with the balance wheel 35.

[0064] Such a regulating organ 60 has a high oscillation frequency. Thus, a reduced-inertia escapement mechanism 50 according to the invention can operate optimally at this frequency.

[0065] 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.

Claims

1. Clockwork mobile (1, 10, 20, 30), in particular for an escapement mechanism (50), the mobile (1, 10, 20, 30) comprising a central hub (2) and a circular peripheral toothing (4, 14, 24), the hub (2) being arranged inside the peripheral toothing (4, 14, 24), substantially in the same principal plane, the mobile (1, 10, 20, 30) comprising a first series of blades (5, 15) connecting the hub (2) to the peripheral toothing (4), the blades (5, 15) being distributed around the hub (2) in the principal plane, characterized in that the blades (5, 15) are arranged substantially tangentially to the circumference of the hub (2), the direction of the blades (5) forming an angle between -20° and +20° with the tangent to the hub (2), preferably between -10° and +10°, or even between -5° and +5°.

2. Clockwork mechanism according to claim 1, characterized in that It has a rotational inertia of less than 5 mg.mm 2 , preferably less than 3 mg / mm³ 2, or even less than 2 mg / mm³ 2 .

3. Clockwork mechanism according to claim 1 or 2, characterized in that The thickness of the blade (5, 15) follows the following equation: e ≤ h 3 preferably e ≤ h 5 , Or h is the height of the blade (5, 15).

4. Clockwork mechanism according to any one of the preceding claims, characterized in that Each blade (5, 15) of the first series is arranged in a direction making an angle with the direction of the preceding blade, in which the angle α = 2 π N , Or N is the number of blades (5, 15) in the first series.

5. Clockwork mechanism according to any one of the preceding claims, characterized in that the blades (5, 15) of the first series are distributed evenly around the hub (2).

6. Clockwork mechanism according to any one of the preceding claims, characterized in that blades (5, 15) of the first series are straight.

7. Clockwork mechanism according to any one of the preceding claims, characterized in that It includes a second series of blades (6, 16) connecting the hub (2) to the peripheral teeth (4, 14, 24) in the main plane, so as to form a network of blades (5, 15, 6, 16) intersecting with the first series of blades (5, 15).

8. Clockwork mechanism according to claim 7, characterized in that the blades (6, 16) of the second series are arranged substantially tangentially to the hub (2).

9. Clockwork mechanism according to claim 7 or 8, characterized in that The network forms a star-shaped structure.

10. Clockwork mechanism according to any one of claims 7 to 9, characterized in that the blades (16) of the second series are curved.

11. Clockwork mechanism according to any one of claims 7 to 10, characterized in thatthe peripheral dentition (24) comprises teeth (28), each tooth (28) being arranged at the junction of the free ends of a blade (15) of the first series and a blade (16) of the second series.

12. Clockwork mechanism according to any one of the preceding claims, characterized in that the peripheral teeth (4, 14) includes an annular rim (9, 19) with teeth (8, 18).

13. Clockwork mechanism according to claim 12, characterized in that the annular rim (19) is hollowed out.

14. Escapement mechanism (50) comprising an anchor (21) and a first clockwork mobile (30) according to any one of the preceding claims, the first clockwork mobile (30) forming the escape wheel of the escapement mechanism (50).

15. Escapement mechanism according to claim 14, characterized in thatit includes a second clockwork mobile (20) according to any one of the preceding claims, the second clockwork mobile (20) meshing with the first clockwork mobile (30), as an intermediate mobile between the seconds mobile and the escapement mobile.

16. Watch movement comprising an escapement mechanism (50) according to claim 14 or 15.

Images