DEVICE FOR AUTONOMOUS ADJUSTMENT OF THE ACTIVE LENGTH OF A COIL SPRING

Description

Technical field of the invention

[0001] The invention relates to an autonomous adjustment device for the active length of a spiral, for a balance-spiral type oscillator.

[0002] The invention also relates to a watch movement comprising the autonomous adjustment device for the active length of a balance spring and a balance-spring type oscillator.

[0003] The invention further relates to a timepiece, in particular a watch, comprising the watch movement. Technological background

[0004] In the field of watches equipped with mechanical oscillators of the balance-spring type, there are known mechanisms for manually adjusting the active length of the spring.

[0005] For example, in common manual adjustment mechanisms, the outer end of the balance spring is held in place by a stud attached to a stud holder fixed to a balance cock. A regulator, which rotates relative to the stud holder, is used to adjust the active length of the balance spring, thus allowing adjustment of the balance wheel's frequency. The regulator is a lever, usually with two arms, that pivots centered on the balance staff. One arm of the regulator, for example, carries two pins between which the balance spring is free. A second arm of the regulator can be manually operated to rotate the regulator through a certain angle around the balance staff. This allows the actual position of the counting point to be changed. When the regulator rotates, the active length of the balance spring is shortened or lengthened.However, a drawback of such a manual adjustment system is that gravity influences the frequency of the balance wheel and hairspring oscillations depending on the orientation of the corresponding watch movement. Thus, a watch's rate can vary significantly between its horizontal and vertical positions, for example. Furthermore, when the hairspring moves between the pins due to play between them, the oscillations of the balance wheel and hairspring cause a disturbance in its active length and therefore a slight variation in the frequency of the overall balance wheel and hairspring oscillations.

[0006] To limit the negative effects of gravity, a solution is known, notably from patent document CH 705 605 B1, implementing a device for adjusting the active length of the balance spring. In this device, the regulator incorporates clamping means designed to pinch a terminal portion of the balance spring to define its active length. The outer end of the balance spring is further secured to a fastening system mounted movably relative to the regulator and arranged to cooperate with it. The clamping means, consisting, for example, of a pin-eccentric clamping system in which the terminal portion of the balance spring is pinched, can be loosened or tightened at will by a watchmaker.When the watchmaker loosens the pin-eccentric clamping system, they can move the fixing system using a tool, thus moving the balance spring relative to the fixed regulator and therefore relative to the pin, thereby altering the active length of the balance spring. The watchmaker can then clamp the balance spring against the pin by tightening the clamping system to return the regulating device to its operating position. However, this solution remains a manual adjustment method, which has the drawback of significantly limiting the precision of the adjustment needed to counteract the effects of gravity. Furthermore, this solution is tedious to implement due to the various manual adjustment steps required by the watchmaker.

[0007] Document EP 3 502 788 A1 concerns a device for adjusting the active length of a balance spring, for a balance-spring type oscillator, allowing the effects of gravity to be counterbalanced, in particular disturbances to the isochronism of the oscillator's balance wheel, Summary of the invention

[0008] The invention therefore aims to provide a device for adjusting the active length of a spiral, for a balance-spring type oscillator, allowing to counterbalance in a simple, precise and autonomous way the effects of gravity, in particular the perturbations of the isochronism of the balance wheel of the oscillator, and overcoming the aforementioned disadvantages of the prior art.

[0009] To this end, the invention relates to an autonomous adjustment device for the active length of a balance spring, for a balance-spring type oscillator, comprising a cock mounted on a plate of a watch movement and in which a balance shaft pivots, the balance spring having an inner end fixed to the balance shaft and an outer end fixed to a first stud attached to a stud holder, the stud holder being pivotally mounted on the cock concentrically to the balance shaft, and means for modifying the active length of the balance spring.

[0010] According to the invention, the means for modifying the active length of the spiral include: a lever capable of pivoting on the stud carrier between a rest position and two correction positions of the device, the lever having a first free end and a second end (601) having two prongs (601, 602); elastic constraint means configured to exert an elastic restoring action in position on the lever; a movable weight rotating about a shaft on which a cam is mounted, the weight being arranged to rotate freely about the shaft according to gravity, the rotation of the weight causing a rotation of the cam and a pivoting of the lever so that one of the prongs acts on the spiral and simultaneously modify the active length of the spiral;damping means comprising a toothed wheel coaxial with and mounted on the weight, and a damping device arranged to cooperate with the weight via the toothed wheel and limit the change in the active length of the balance spring in the event of sudden acceleration or deceleration.

[0011] In accordance with other advantageous variants of the invention: The stud holder includes an extension with an opening through which a pivot axis for the lever passes; the lever includes, at its second end, a ball bearing through which the pivot axis passes; the opening is oblong in shape to allow adjustment of the position of the lever relative to the spiral; the elastic constraint means configured to exert an elastic return action on the lever are integral with the plate; the elastic constraint means configured to exert an elastic return action on the lever are integral with the stud holder; the cam is a radial cam with an external profile; in the rest position of the device, a flat portion of the cam is in contact with the lever, and, in the correction position of the device, a corner or angle of the cam is in contact with the lever;The cam is in permanent contact with the free end of the lever regardless of the position of the weight; the weight is a solid half-disc; the device includes an air damper, the damper being in the form of a body with a cavity similar in shape to that of the weight, the weight being arranged to pivot in the cavity; the device includes a heart-shaped cam mounted on the shaft, the heart-shaped cam being arranged to cooperate with a spring, the assembly forming a lever position reset device; the heart-shaped cam is superimposed on the cam.

[0012] An advantage of the adjustment device according to the invention lies in the fact that it comprises a freely rotating weight that indirectly cooperates with a movable arm arranged to act on the outer coil of the balance spring. Rotation of the weight, freely subjected to gravity, thus causes a displacement of the arm between a rest position and a correction position of the device, and simultaneously acts on the balance spring to modify its active length, allowing it to be adjusted to compensate for perturbations in the balance wheel's isochronism due to gravity. Consequently, the adjustment device according to the invention makes it possible to precisely compensate for the oscillator's rate as a function of its position in space, counterbalancing perturbations in the balance wheel's isochronism due to gravity, and to do so autonomously.

[0013] The invention also relates to a watch movement comprising the setting device described above, and which includes the features mentioned in dependent claim 14.

[0014] The invention also relates to a timepiece comprising the clock movement described above, and which includes the features mentioned in dependent claim 15.

[0015] Other features and advantages of the present invention will become apparent in the following description of a preferred embodiment, presented by way of non-limiting example with reference to the accompanying drawings. Brief description of the figures

[0016] The purposes, advantages, and characteristics of the device for adjusting the active length of a balance spring, as well as of the watch movement and the timepiece comprising it, will become clearer from the following description based on at least one non-limiting embodiment illustrated by the drawings in which: there figure 1 is a top-view perspective of a watch movement comprising a device for adjusting the active length of a balance spring according to a first embodiment of the invention; the figure 2 is a top-view perspective of a watch movement comprising a device for adjusting the active length of a balance spring according to a first embodiment of the invention; the figure 3 is a top perspective view of the adjustment device of the figure 1 according to the first embodiment of the invention; the figure 4 an exploded perspective view of the adjustment device figure 1 according to the first embodiment of the invention; The figures 5a And 5b are respectively top perspective and exploded views of the adjustment device of the figure 1 according to a second embodiment of the invention. Detailed description of the invention

[0017] The following description refers to a watch movement equipped with a device for adjusting the active length of a balance spring, for a balance-spring type oscillator. The usual components of a watch movement, which are well known to a person skilled in this technical field, are described only in simplified form or not at all. A person skilled in the art will be able to adapt these various components and make them work together for the operation of the watch movement. In particular, everything concerning the escapement mechanism of the watch movement will not be described hereafter, although such an escapement mechanism could advantageously cooperate with the adjusting device according to the invention.

[0018] There figure 1 represents a part of a timepiece 1, which includes a watch movement 2. In the particular embodiment example of the figure 1The timepiece 1 is a watch. The watch movement 2 comprises an oscillator equipped with a balance wheel 4 and a balance spring 5, and a device 6 for independently adjusting the active length of the balance spring 5. Conventionally, the balance spring 5 is attached to a balance shaft 7 by its inner end (not visible). The balance shaft 7 has one end pivotally mounted in a balance bridge (the latter not shown in the figures for clarity). The outer end of the balance spring 5 is conventionally attached to a stud 8 fixed to a stud holder 10, the stud holder 10 being secured to a balance cock 12 by slight clamping. More precisely, the stud holder 10 is pivotally mounted on the balance cock 12 concentrically with the balance shaft 7, as illustrated in the figure. figure 2 . The shaft 7 of the balance wheel 4 is pivotally mounted in the cock 12.

[0019] The means 6 for modifying the active length of the spiral 5 are suitable for modifying the active length of the spiral 5 by acting on the length of the outer coil of the spiral 5. In the two embodiment examples respectively illustrated on the figures 1 to 4 and the figures 5a And 5b The means for modifying the active length of the balance spring 5 include a lever 60 capable of moving between a rest position and two correction positions of the device. The lever has a first free end 610 and a second end 600 equipped with two jaws 601, 602, each jaw 601, 602 being arranged to act independently of each other on the outer coil of the balance spring and modify the active length of the balance spring.

[0020] As can be seen in the figures, the eyelet holder 10 includes an extension 100 with an opening 101 through which passes a pivot axis 102 around which the lever 60 pivots to move from its rest position to a correction position.

[0021] In order to pivot around the axis 102 which is formed by a bolt 103 and a nut 104, the lever includes, at its second end 600, a ball bearing 603 through which passes the rod of the bolt 103.

[0022] It should also be noted that the opening 101 is oblong in shape in order to allow adjustment of the position of the lever 60 relative to the spiral 5. Thus, once the correct position of the lever is determined, it is sufficient to fix the second end 600 of the lever onto the extension 100 of the stud holder by tightening the bolt 103 and the nut 104.

[0023] The means 6 for modifying the active length of the balance spring also include a weight 40 that rotates about an axis 30 on which a cam 31 is mounted, against which the free end 610 of the lever 60 rests. The weight 40 is arranged to rotate about the axis 30 according to the gravity acting upon it, the rotation of the weight 40 causing a rotation of the cam 31 and a displacement of the lever 60 to act on the outer coil of the balance spring 5 and simultaneously modify the active length of the balance spring.

[0024] The adjustment device 6 further includes damping means comprising a toothed wheel 34 coaxial with the weight 40 and integral with the weight, and a damping device 20 arranged to cooperate with the weight 40 via the toothed wheel 34 and limit the modification of the active length of the spiral 5 in the event of sudden acceleration or deceleration.

[0025] The adjustment device includes elastic constraint means configured to exert an elastic restoring action in position on at least one arm 60. The elastic constraint means are in the form of a leaf spring 70, 73. According to the first embodiment illustrated in figures 1 to 4 The spring blade 70 comprises a first end 71 in contact with the free end 610 of the lever 60 so as to hold the free end 610 against the profile of the cam 31, and a second end integral with the plate 13. According to the second embodiment illustrated in figures 5a And 5b , the spring blade 73 is integral with the stud holder 10 and also allows the free end 610 to be pressed against the profile of the cam 31.

[0026] The means for modifying the active length of the spiral 5 include two pins 19 fixed to the second pin 8', the second end 601 of the arm 60 being arranged so that it slides between the two pins 19 and comes into contact with the outer coil of the spiral 5 in the correction position and thus modify the active length of the spiral.

[0027] The weight 40 is mounted to rotate freely on the axis 30 on which the cams 31 are mounted, such that a rotation of the weight 40 causes a displacement of the lever 60 and simultaneously acts on the means for modifying the active length of the balance spring 5. The displacement of the lever under the effect of the rotation of the weight 40, itself subject to gravity, occurs between a rest position of the device and two correction positions of the device. The prongs 601 and 602 of the lever 60 allow for a distinct correction depending on the position of the watch. As illustrated in the figures, the weight 40 is, for example, made of a semi-solid disc. In an alternative embodiment not shown in the figures, the weight 40 is made of a solid, two-material disc, the two materials of the disc having distinct densities.

[0028] Thus, depending on the position of the watch movement 2 in space, the weight 40, freely subjected to gravity, can rotate around its axis of rotation and thus cause a displacement of the lever 60. In doing so, the rotation of the weight 40 acts simultaneously on the means of modifying the active length of the balance spring 5, allowing continuous adjustment of the active length of the balance spring in order to compensate for the perturbations of the isochronism of the balance wheel due to gravity.

[0029] To prevent the weight from freewheeling and disrupting the oscillator 4, 5 instead of correcting it, the adjustment device 6 includes damping means comprising a toothed wheel 34 coaxial with and integral to the weight. The damping means include a damping device arranged to cooperate with the weight via the toothed wheel to limit, or even prevent, changes in the active length of the balance spring 5 during sudden acceleration or deceleration.

[0030] As illustrated in the figures, the damping device 20 is in the form of an air damper. The damper comprises a body 22 with a cavity in which a mass 21, similar in shape to the cavity, rotates around an axis 24. The axis 24 also includes a pinion 23 arranged to mesh with the teeth of the gear 34. Thus, when the weight 40 moves, it drives the gear 34, which engages the pinion 23, and rotates the mass 21 of the damping device 20. It is therefore understood that during a rapid movement of the weight 40, the mass 21 will dampen its rotation thanks to the damping device 20. Of course, other types of dampers can be used, such as a mass moving within a cylinder, or even a magnetic damper.

[0031] It will be noted that the shaft 30 carrying the weight 40, the toothed wheel 34 and the cam 31, also includes a heart-shaped cam 32 fixed to the shaft 30, and superimposed on the cam 31. The heart-shaped cam 32 is arranged to cooperate with a spring 24, 25 whose end 26 cooperates with the profile of the heart-shaped cam 32, the whole thus forming a device for resetting the position of the lever 60 to return it to its rest position naturally when the weight is no longer subject to gravity.

[0032] Preferably, cam 31 is a radial cam with an external profile. Although a radial cam with a substantially rectangular external profile is shown on the figures 1 to 5bIn practice, the shape envisaged for the external profile of the cam will depend on the type of spiral 5 used and the correction to be applied. For example, a radial cam with a triangular, oblong, or even ovoid external profile can also be used within the framework of the present invention. Preferably, in the rest position of the adjusting device 6, a flat portion of the cam is in contact with the free end 610 of the lever 60, while in the correction position of the device 6, a corner or angle of the cam 31 is in contact with the free end 610 of the lever 60. Even more preferably, the cam 31 is in contact with the lever 60 regardless of the position of the weight 40.

[0033] It is thus understood that, depending on the position of the watch movement 2 in space, the weight 40, freely subject to gravity, can rotate around its axis of rotation and thereby cause a displacement of the lever 60. In doing so, this rotation of the weight 40 simultaneously acts on the means for modifying the active length of the balance spring 5, allowing continuous adjustment of the active length of the balance spring to compensate for perturbations in the isochronism of the balance wheel due to gravity. The rotation of the weight 40 causes a rotation of the axis 30 and has the effect of displacing the cam 31, which is fixed to the axis 30. The cam then acts on the free end 610 of the lever 60 and displaces the latter so that the other end 600 of the lever pivots around the axis 102 and one of the jaws 601 comes into contact with the balance spring 5 in order to modify the active length of the balance spring.

[0034] Once the weight has stabilized following its change of position, the device will return by itself to the rest position thanks to the action of the spring 24, 25 on the heart-shaped cam 32 which is also attached to the axis 30.

[0035] The invention also relates to a watch movement 2 comprising a balance-spring type oscillator 4, 5 and an autonomous adjustment device 6 for the active length of the spring 5 as described above.

[0036] The invention also relates to a timepiece 1 comprising a watch movement 2 equipped with a device 6 for autonomously adjusting the active length of the balance spring 5 as described above.

Claims

1. Device (6) for autonomously adjusting the active length of a balance spring (5), for an oscillator (4, 5) of the sprung balance type, comprising a cock (12) designed to be mounted on a plate (13) of a horological movement (2) and in which cock a staff (7) of the balance (4) can pivot, the balance spring (5) including an inner end integral with the staff (7) of the balance (4) and an outer end designed to be integral with a first stud (8) fastened to a stud-holder (10), the stud-holder (10) being pivotally mounted on the cock (12) concentrically with the staff (7) of the balance (4), and means for modifying the active length of the balance spring (5); In which the means for modifying the active length of the balance spring comprise: - a lever (60) capable of pivoting on the stud-holder (10) between a rest position and two correction positions of the device, the lever (60) having a first free end (600) and a second end (601) having two beaks (601, 602); - resilient stressing means (70, 71, 72, 73) configured to exert a resilient restoring action on the lever (60); - an inertia block (40) rotatable about a shaft (30) on which a cam (31) is mounted, the inertia block being arranged to rotate freely about the shaft as a function of gravity, the rotation of the inertia block (40) rotating the cam (31) and pivoting the lever (60) so that one of the beaks (601, 602) acts on the balance spring and simultaneously modifies the active length of the balance spring (5); - damping means comprising a toothed wheel (34) coaxial with the inertia block (40) and mounted on the inertia block, and a damping device (20) arranged to cooperate with the inertia block via the toothed wheel and to limit the change in the active length of the balance spring (5) in the event of sudden acceleration or deceleration.

2. Device (6) for autonomously adjusting the active length of a balance spring (5) according to claim 1, characterised in that the stud-holder (10) comprises an extension (100) provided with an opening (101) through which passes a pivot pin (102) for the lever (60).

3. Device (6) for autonomously adjusting the active length of a balance spring (5) according to claim 2, characterised in that the lever comprises, at its second end (600), a ball bearing (603) through which the pivot pin (102) passes.

4. Device (6) for autonomously adjusting the active length of a balance spring (5) according to claim 2, characterised in that the opening (101) is oblong in shape in order to be able to adjust the position of the lever (60) relative to the balance spring (5).

5. Device (6) for autonomously adjusting the active length of a balance spring (5) according to one of claims 1 to 4, characterised in that the resilient stressing means (70, 71, 72) configured to exert a resilient restoring action on the lever are designed to be integral with the plate (13).

6. Device (6) for autonomously adjusting the active length of a balance spring (5) according to one of claims 1 to 4, characterised in that the resilient stressing means (73) configured to exert a resilient restoring action on the lever are integral with the stud-holder (10).

7. Device (6) for autonomously adjusting the active length of a balance spring (5) according to one of claims 1 to 6, characterised in that the cam (31) is a radial cam with an external profile.

8. Device (6) for autonomously adjusting the active length of a balance spring (5) according to one of claims 1 to 7, characterised in that, when the device (6) is in the rest position, a flat portion of the cam (31) is in contact with the lever (60), and when the device (6) is in the correction position, a corner or angle of the cam (31) is in contact with the lever (60).

9. Device (6) for autonomously adjusting the active length of a balance spring (5) according to one of claims 1 to 8, characterised in that the cam (31) is in permanent contact with the free end (610) of the lever (60) whatever the position of the inertia block (40).

10. Device (6) for autonomously adjusting the active length of a balance spring (5) according to any one of the preceding claims, characterised in that the inertia block (21) is a solid half-disc.

11. Device (6) for autonomously adjusting the active length of a balance spring (5) according to one of the preceding claims, characterised in that the device comprises an air damper, the damper being in the form of a body with a cavity of similar shape to that of the inertia block, the inertia block being arranged to pivot in the cavity.

12. Device (6) for autonomously adjusting the active length of a balance spring (5) according to one of the preceding claims, characterised in that it comprises a heart-shaped cam (32) mounted on the shaft (30), the heart-shaped cam being arranged to cooperate with a spring (24, 25), the assembly forming a device for resetting the position of the lever (60).

13. Device (6) for autonomously adjusting the active length of a balance spring (5) according to claim 12, characterised in that the heart-shaped cam (32) is superimposed on the cam (31).

14. Horological movement (2) including an oscillator (4, 5) of the sprung balance type and a device (6) for autonomously adjusting the active length of the balance spring (5), characterised in that the autonomous adjustment device (6) is in accordance with any one of the preceding claims.

15. Timepiece (1) including a horological movement (2), characterised in that the horological movement (2) is in accordance with claim 14.