LIFTING DEVICE, IN PARTICULAR FOR A CLOCK CYLINDER, WITH A REMOVAL LIFTING SAFETY DEVICE

Description

Technical field of the invention

[0001] The invention relates to a winding device, in particular for a watch barrel, equipped with a disengageable winding gear.

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

[0003] Most modern self-winding mechanical watches generally feature an oscillating weight that drives a gear train by gravity. The rotation of this gear train winds a mainspring, the barrel spring, which is wound in a drum around a shaft, by driving the shaft itself. The rotation is usually forced in only one direction and is prevented from reversing by a pawl.

[0004] However, when the spring is fully wound, over-winding must be avoided as it could cause the spring to break, or the oscillator to bounce back, during which the amplitude of oscillation increases to the point that the balance wheel comes to rest against the anchor horns, and causes a drift in rate due to the rebound of the balance wheel against these stops.

[0005] To avoid these risks, such cylinders generally have a system for limiting the winding of the cylinder spring.

[0006] This limitation is generally achieved by the outermost leaf of the spring sliding against the inner wall of the drum. When the spring is fully wound and coiled around the barrel's winding arbor, the last wound coil presses against the outer wall of the drum.

[0007] Thus, when the winding torque exceeds the friction torque against the wall of the last coil, the coil begins to slip. To prevent uncontrolled slippage, notches at the end of the blade allow it to stop sliding as soon as the winding torque has decreased sufficiently.

[0008] However, the drawback of such a system lies in the sliding and friction process of the last coil inside the drum. Indeed, when the driven mechanism requires significant torque, the pressure forces and friction of the spring leaf against the wall are increased, leading to wear and a degradation of the barrel's performance, even in the presence of grease, which is eventually washed away from the friction track.

[0009] Furthermore, within an automatic barrel, it is necessary to meet contradictory criteria to maximize efficiency, such as reduced friction between the coils, and significant friction between the spring and the drum to guarantee good winding torque.

[0010] Damage to the drum must also be avoided, such as the tearing off of the coating, the formation of sludge, and the wear of the walls under the pressure of the fully wound spring blade.

[0011] Document CH264966A describes a device for limiting the tension of the mainspring in a self-winding timepiece. Summary of the invention

[0012] The aim of the present invention is to overcome all or part of the disadvantages mentioned above by proposing a winding device equipped with a system for limiting the winding of a spring, which replaces a system based on the sliding of a blade against notches in an internal wall of the drum.

[0013] To this end, the invention relates to a winding device, in particular for a watch barrel equipped with a spring, comprising a ratchet mounted on a rotating winding shaft, the rotating winding shaft being for example a winding shaft of the barrel whose rotation winds the barrel, and a winding gear meshing with the ratchet, the rotation of the winding gear causing the rotation of the ratchet and that of the rotating winding shaft by applying a torque on the ratchet, the winding gear being mobile between an engaged position in which it drives the ratchet and a disengaged position in which it does not drive the ratchet.

[0014] The invention is remarkable in that the winding gear is mounted on a spring exerting a restoring force on the winding gear to keep it in the engaged position.

[0015] Thus, by moving the winding gear train to the disengaged position, the ratchet wheel is no longer driven by the winding gear train, because the latter is no longer driven. For example, when the torque applied to the ratchet wheel is too high, particularly when the mainspring barrel is fully wound, the winding gear train shifts and no longer transmits the rotational torque to the ratchet wheel, so the ratchet wheel stops rotating.

[0016] Thanks to this invention, the risk of premature wear of the cylinder is avoided, as the limiting device is positioned upstream and outside the cylinder. Furthermore, it eliminates the need for conventional winding limiting devices, which rely on spring friction inside the cylinder.

[0017] According to a particular embodiment of the invention, the ratchet comprises a first peripheral toothing cooperating with a second toothing of the winding gear, when the torque applied to the ratchet is substantially less than a threshold value.

[0018] According to a particular embodiment of the invention, the winding gear moves into the disengaged position when the torque applied to the ratchet wheel substantially exceeds a threshold value, in particular when the barrel is fully wound.

[0019] According to the invention, the winding gear meshes with a winding actuation mechanism when it is in the engaged position, and does not mesh with the winding actuation mechanism when it is in the disengaged position.

[0020] According to a particular embodiment of the invention, the winding gear is arranged next to the ratchet, and preferably extends in the same plane as the ratchet in the engaged position.

[0021] According to a particular embodiment of the invention, the winding gear makes a lateral movement between the engaged position and the disengaged position.

[0022] According to a particular embodiment of the invention, the winding gear performs a rotary movement to move from the engaged position to the disengaged position and vice versa.

[0023] According to the invention, the spring comprises a flexible guide forming a virtual pivot, the winding gear being suspended by the flexible guide, the flexible guide exerting a radial restoring force on the winding gear in the direction of the actuating mobile.

[0024] According to a particular embodiment of the invention, the flexible guide is provided with two uncrossed flexible blades and a rigid moving element supporting the winding gear, the two uncrossed flexible blades connecting the rigid moving element to a fixed support of the winding device.

[0025] According to a particular embodiment of the invention, the ratchet is mounted integrally on the barrel, the rotating winding shaft being the winding shaft of the barrel allowing the barrel spring to be wound.

[0026] The invention also relates to a watch movement comprising a barrel, the watch movement having such a barrel winding device. Brief description of the figures

[0027] 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 top view of a winding device according to an embodiment of the invention, in the engaged position, the figure 2 schematically represents a top view of the winding device according to the embodiment of the invention of the figure 1 , during the reassembly of the barrel, and the figure 3 schematically represents a top view of the winding device according to the embodiment of the invention of the figure 1 , in the disengaged position, particularly when the barrel spring is fully wound. Detailed description of the invention

[0028] THE figures 1 to 3represent an embodiment of a winding device 1, here of a watch barrel 2, according to the invention.

[0029] The winding device 1 of the barrel 2 includes a ratchet 3 and a winding train 4. The winding train 4 meshes with the ratchet 3, so that when the winding train 4 is set in rotation in a first direction, the ratchet 3 is driven in rotation in a second direction opposite to the first direction.

[0030] The ratchet 3 is mounted rigidly on a winding shaft, the winding shaft enabling the winding of the barrel 2. The winding shaft is preferably cylindrical.

[0031] In the example, the winding shaft is the winding shaft of the barrel 2, the ratchet 3 being arranged on the barrel 2. The ratchet 3 includes a hub 7 mounted integrally on the winding shaft.

[0032] In a variant, not shown in the figures, the winding shaft is not mounted on the barrel, the winding shaft comprising a pinion engaging with a moving part driving the winding shaft of the barrel to wind the spring, if the ratchet is not mounted on the barrel.

[0033] The winding gear 4 is arranged next to the ratchet 3, and preferably extends in the same plane as the ratchet 3.

[0034] The ratchet 3 includes a first external toothing 11 distributed around the ratchet 3. The first toothing 11 cooperates with a second toothing 12 arranged on the winding train 4. The winding train 4 includes a pinion having the second toothing 12 arranged on its periphery.

[0035] Barrel 2 contains a spiral spring (not shown in the figures), arranged inside barrel 2, which must be wound either by an automatic winding system or by a manual winding system.

[0036] To this end, the winding device 1 further comprises a gear train 13, for example driven by an automatic winding weight (not shown in the figures) of the watch movement. The gear train 13 can also be driven by a winding stem (not shown in the figures) operated by means of a crown, in the case of manual winding.

[0037] An actuation mobile 21 for the winding of the gear train 13 includes a third tooth 14 meshing with the second tooth 12 of the winding train 4. Thus, by actuating the gear train 13, a torque is applied to the ratchet 3, which transmits it at least in part to the winding shaft via the winding train 4 driven by the actuation mobile 21, and via the ratchet 3 driven by the winding train 4.

[0038] The rotation of the winding gear 4 causes the rotation of the ratchet 3, and therefore of the winding shaft, when the barrel 2 is wound.

[0039] To avoid over-winding the barrel, the winding gear 4 is mobile between an engaged position in which it drives the ratchet 3 and a disengaged position in which it does not mesh with the ratchet 3.

[0040] In particular, the winding gear 4 engages with the winding drive wheel 21 when it is in the engaged position, and it does not engage with the winding drive wheel 21 when it is in the disengaged position.

[0041] Thus, in the engaged position, the drive wheel 21 drives the winding gear 4, and the winding gear 4 drives the ratchet wheel 3. Whereas in the disengaged position, the drive wheel 21 spins freely and does not drive the winding gear 4, which is at a distance from the drive wheel 21, so that the ratchet wheel 3 is no longer driven by the winding gear 4.

[0042] According to the invention, the winding gear 4 is mounted on a spring 5 exerting a force on the winding gear 4 to keep it in the engaged position.

[0043] The spring 5 includes a flexible guide forming a virtual pivot, the winding gear 4 being suspended from the flexible guide. The flexible guide is provided with two uncrossed flexible blades 15 and a rigid movable element 16 supporting the winding gear 4. The two flexible blades 15 connect the rigid movable element 16 to a fixed support 17 of the winding device 1.

[0044] The fixed support 17 includes, for example, a ratchet bearing 3. The flexible blades 15 meet and are connected to the bearing on one side, and spread apart to the ends of the rigid moving element 16. The rigid moving element 16 here has the shape of an arc of a circle.

[0045] The flexible guide exerts a radial restoring force on the winding gear 40 in the direction of the actuating mobile 21.

[0046] In addition, the winding gear 4 moves into a disengaged position when the torque applied to the ratchet 3 significantly exceeds a threshold value, particularly when the barrel 2 is fully wound.

[0047] Thus, when the torque significantly exceeds a threshold value, the winding gear rotates to move from the engaged to the disengaged position. Winding gear 4 moves laterally between the engaged and disengaged positions. Furthermore, winding gear 4 rotates around the virtual pivot to move from the engaged to the disengaged position and vice versa.

[0048] Beyond the threshold value, when the torque required to rotate the ratchet wheel 3 is greater than that required to bend the flexible guide, the winding gear 4 is pushed back by the actuating wheel 21 into the disengaged position. In other words, when the winding gear 4 exerts strong pressure on the ratchet wheel 3, the rigid moving element 16 and the winding gear 4 move because the flexible blades 15 of the flexible guide bend.

[0049] Therefore, the drive wheel 21 continues to rotate, but the winding gear 4 and the ratchet 3 no longer rotate.

[0050] On the figure 1 In the winding configuration, the winding torque exerted on the ratchet 3 is less than the threshold value, so that the winding train 4 remains in the engaged position and meshes with the actuating wheel 21. Thus, the ratchet 3 and the winding shaft are driven by the winding train 4. The first peripheral toothing 11 of the ratchet 3 cooperates with the second toothing 12 of the winding train 4 when the torque applied to the ratchet 3 is substantially less than a threshold value.

[0051] On the figure 2, during the winding of the barrel, when the torque increases and approaches the threshold value, the winding gear 4 begins to move laterally thanks to the flexible guide, but it still meshes with the third tooth 14 of the actuating mobile 21. Thus, the ratchet 3 is still driven by the winding gear 4.

[0052] On the figure 3 , when the barrel 2 is fully wound, the winding torque exerted on the ratchet 3 by the winding gear 4 is greater than the threshold value, so that the winding gear 4 moves completely into the disengaged position thanks to the flexible guide.

[0053] Consequently, the second tooth 12 of the winding gear 4 no longer has contact with the third tooth 14 of the actuating wheel 21. Thus, the winding gear 4 and the ratchet 3 do not rotate.

[0054] These disengagement mechanisms protect cylinder 2 from over-cocking and prevent premature wear inside cylinder 2.

[0055] The barrel 2 also includes a fourth peripheral toothed section 18 configured to cooperate with a fourth toothed section 19 of a moving part 20 of the watch movement. The moving part 20 is, for example, a center wheel. Once wound, the barrel 2 supplies the energy necessary for the operation of the watch movement via the moving part 20.

[0056] The invention also relates to a clockwork movement, not shown in the figures, the movement comprising a barrel and a barrel winding device as described above.

[0057] 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 annexed claims.

Claims

1. A winding device (1), in particular for a spring-loaded barrel (2), comprising a ratchet (3) fitted to a rotary winding arbor, the rotary winding arbor being, for example, a winding arbor on the barrel (2) which, when rotated, winds the barrel (2), and a winding train (4) meshing with the ratchet (3), the rotation of the winding gear (4) driving the rotation of the ratchet (3) and that of the rotary winding arbor by applying a couple to the ratchet (3), the winding train (4) being mobile between a coupled position in which it drives the ratchet (3) and an uncoupled position in which it does not drive the ratchet (3) the winding train (4) being fitted on a spring (5) exerting a return force on the winding train (4) to keep it in the coupled position, the winding train (4) meshing with a winding actuator mobile (21) when in the coupled position, and not meshing with the winding actuator mobile (21) when in the uncoupled position, characterised in that the spring (5) comprises a flexible guide forming a virtual pivot, the winding train (4) being suspended by the flexible guide, the flexible guide exerting a radial return force on the winding train (4) towards the actuator mobile (21).

2. The winding device according to claim 1, characterised in that the winding train (4) moves to the uncoupled position when the couple applied to the ratchet (3) substantially exceeds a threshold value, in particular when the barrel (2) is fully wound.

3. The winding device according to claim 1 or 2, characterised in that the winding train (4) is arranged beside the ratchet (3) and, when in the coupled position, extends preferably in the same plane as the ratchet (3).

4. The winding device according to any of the preceding claims, characterised in that the winding train (4) moves laterally between the coupled position and the uncoupled position.

5. The winding device according to claim 3 or 4, characterised in that the winding train (4) executes a rotary movement to move from the coupled position to the uncoupled position and conversely.

6. The winding device according to any of the preceding claims, characterised in that the flexible guide is fitted with two uncrossed flexible blades (15) and a rigid mobile element (16) supporting the winding train (4), the two uncrossed flexible blades (15) connecting the rigid mobile element (16) to a fixed support (17) on the winding device (1).

7. A horological movement comprising a barrel (2) and a winding device (1) for the barrel (2) according to any of the preceding claims.