Device for the autonomous adjustment of the active length of a hairspring

Abstract

The present invention relates to a device (6) for autonomous adjustment of the active length of a balance spring (5), for a balance-spring type oscillator (4, 5), comprising a cock (12) mounted on a plate (13) of a watch movement (2) and in which a balance shaft pivots, the balance spring (5) having an inner end fixed to the balance shaft and an outer end fixed to a stud (8) attached to a stud holder (10), the stud holder (10) being pivotally mounted on the cock (12) concentrically with the balance shaft, and means for modifying the active length of the balance spring (5).

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 discloses a device for autonomously adjusting the active length of a balance spring. 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 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 first arm capable of moving between a rest position and a correction position of the device, at least one arm having a first free end and a second end cooperating with a first pair of pins fixed on the eyelet holder, the pair of pins being angularly offset with respect to the eyelet; a second arm capable of moving between a rest position and a correction position of the device, the second arm having a first free end and a second end cooperating with a second pair of pins mounted on the eyelet holder, the second pair of pins being angularly offset with respect to the first pair of pins; elastic constraint means configured to exert an elastic restoring action in position on each arm;two weights, each movable in translation in orthogonal planes, the weights being arranged to move in translation according to gravity, the movement of at least one of the weights causing in rotation a shaft on which a first cam is mounted, the rotation of the first cam causing a movement of the arm to act on the spiral and simultaneously modify the active length of the spiral, and a second cam arranged to cooperate with the second arm and move it in translation to act on the spiral and simultaneously modify the active length of the spiral; elastic return means configured to exert an elastic action of restoring position on the weights.

[0011] In accordance with other advantageous variants of the invention: Each weight comprises a toothed sector arranged to cooperate with a pinion fixed to the shaft; the elastic return means are in the form of a pair of leaf springs disposed at each end of each weight; the cams are radial cams with an external profile; the cams are angularly offset from each other; in the rest position of the device, a flat portion of each cam is in contact with an arm, and, in the correction position of the device, a corner or angle of the cam is in contact with one of the arms; the cams are in permanent contact with the free end of each arm regardless of the position of the weight;the free end of the first arm includes elastically deformable adjustment means, the adjustment means being in the form of a spring blade, one end of which is fixed to the arm and the other end is free, the free end being arranged to be subjected to stress and adjust the length of the first arm; the free end of the second arm includes elastically deformable adjustment means, the adjustment means being in the form of a spring blade, one end of which is fixed to the arm and the other end is free, the free end being arranged to be subjected to stress and adjust the length of the second arm; the device includes elastic stress adjustment means, the adjustment means being in the form of a screw, the screw passing through the free end and bearing against the arm;The first pair of pins is fixed to the stud holder via a first support, the arm being arranged so that it slides between the two pins and comes into contact with the outer coil of the balance spring in the correction position; the second pair of pins is fixed to the stud holder via a second support, the arm being arranged so that it passes between the two pins and comes into contact with the outer coil of the balance spring in the correction position.

[0012] An advantage of the adjustment device according to the invention lies in the fact that it comprises weights mounted to move in translation and cooperate indirectly with a movable arm arranged to act on the outer coil of the balance spring. A displacement 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 isochronism of the balance wheel due to gravity. Therefore, 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 isochronism of the balance wheel 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. Brief description of the figures

[0015] 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 perspective view of a watch movement comprising a device for adjusting the active length of a balance spring according to the invention; the figure 2an exploded perspective view of the adjustment device figure 1 ; there figure 3 is a top view of the adjustment device of the figure 1 . Detailed description of the invention

[0016] 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.

[0017] There figure 1represents a part of a timepiece 1, which includes a watch movement 2. In the particular embodiment example of the figure 1 The 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 staff (not visible) by its inner end (also not visible). The balance staff 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 staff, as illustrated in the figure. figure 2The balance shaft is pivotally mounted in the balance cock 12.

[0018] 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.

[0019] In a particular example of implementation illustrated on the figure 2The means for modifying the active length of the balance spring 5 comprise a first arm 60 capable of moving between a rest position and a correction position of the device. The first arm 60 has a first free end 600 and a second end 601 cooperating with a first pair of pins 19 forming a guide fork for the first arm 60. The first pair of pins 19 is mounted on the stud holder 10 and offset angularly relative to the stud 8 via a first support 8'. The position of the first support 8' can be modified radially relative to the stud holder 10. Thus, the second end 601 of the arm 60 can slide between the two pins 19 and comes into contact with the outer coil of the balance spring 5 in the correction position to modify the active length of the balance spring.

[0020] The means 6 for modifying the active length of the balance spring also include a pair of linear weights 40, 41 movable in translation in orthogonal planes such that they are superimposed and do not come into contact during their movements. The weights 40, 41 are arranged to move in translation as a function of gravity, the displacement of at least one of the weights 40, 41 causing a shaft 20 to rotate, on which a first cam 30 and a second cam 31 are mounted. Thus, the rotation of the first cam 30 causes a displacement of the first arm 60 to act on the balance spring and simultaneously modify the active length of the balance spring 5, and the same is true for the second cam 31, which is arranged to cooperate with the second arm 61.

[0021] As can be seen in the figure 2Each of the weights 40, 41 is in the form of a linear body having two guide grooves 400, 401, 410, 411 extending along the length of each weight and arranged on opposite faces of each weight. The weights are arranged to slide each within a guide element 50, 51, each guide element comprising rails arranged to cooperate with the guide grooves 400, 401, 410, 411 and guide the weights in translation.

[0022] The guide elements 50, 51 are fixed to the movement plate 13 and include elastic return means configured to exert an elastic return action in position on the weights 40, 41. These elastic return means are in the form of a pair of leaf springs 520, 521, arranged at the distal ends of the guide elements 50, 51 so as to pinch each weight 40, 41 by its ends and thus accompany the movements of each weight and then return them to their original position when the watch returns to a rest position (i.e. a position where the weights are not freely subjected to gravity).

[0023] The spring blades 520, 521 also form shock-absorbing means and prevent sudden movement of the weights 40, 41, and thus limit, or even prevent, the modification of the active length of the spiral 5 during a sudden acceleration or deceleration.

[0024] The adjustment device also includes a second arm 61 capable of moving between a rest position and a correction position of the device, the second arm 61 having a first free end 610 and a second end cooperating with a second pair of pins 19' forming a guide fork for the second arm 61, the second pair of pins 19' being mounted on the stud holder 10 and offset angularly relative to the stud and the first pair of pins 19 via a second support 8". The position of the second support 8" can be modified radially relative to the stud holder 10. Thus, the second end 611 of the second arm 61 can slide between the two pins 19' and comes into contact with the outer coil of the balance spring in the correction position to modify the active length of the balance spring.

[0025] The engagement means also include a second cam 31 arranged to cooperate with the second arm, the free end of which 610 rests against the second cam 31.

[0026] The adjustment device includes elastic constraint means configured to exert an elastic return action on the arms 60, 61. The elastic constraint means are in the form of a rod 62 integral with the arm 60 and a spring blade 63 integral with the eyelet holder 10, the spring blade 61 exerting a return force on the rod 62 and exerting an elastic return action on the arm 60. Elastic constraint means are also associated with the second arm 61, and include a rod 64 integral with the second arm 61 and a spring blade 65 integral with the eyelet holder 10, the spring blade 65 exerting a return force on the rod 64 and exerting an elastic return action on the second arm 61.

[0027] The adjustment device 6 also includes means for adjusting the arms 60, 61, and the free ends 600, 610 of the first and second arms 60, 61, comprising elastically deformable adjustment means for lengthening or shortening the arms. The adjustment means are in the form of a leaf spring, one end of which is fixed to the arm and the other end is free. The free end is arranged to be subjected to tension and to adjust the length of the arms 60, 61, the leaf spring forming a gap between itself and the free end of each arm. Such adjustment is necessary depending on the position of the spiral and the correction required for the spiral.

[0028] Furthermore, each arm 60, 61 includes means for adjusting the elastic stress. These adjustment means take the form of a screw 70, 71, each screw passing through the free end of the spring blade and bearing against the arm. Thus, when the screw is tightened, the free end of the blade moves away, and the distance between the blade and the free end 60, 610 of the arms 60, 61 increases, thereby increasing the length of the arms 60, 61. Conversely, when the screw is loosened, the free end of the blade moves towards the free end, and the distance between the blade and the free end 60, 610 of the arms 60, 61 decreases, thereby increasing the length of the arms 60, 61.

[0029] According to a preferred embodiment, the weights 40, 41 are free to move in translation, each within its own plane, and within the stroke limit imposed by the leaf springs 520, 521. Each weight 40, 41 comprises a toothed sector 402, 412 which is arranged to mesh with a respective pinion 21, 22 of the shaft 20 on which the cams 30 and 31 are mounted, such that a displacement of at least one of the weights 40, 41 causes a displacement of at least one of the arms 60, 61 and simultaneously acts on the means for modifying the active length of the balance spring 5. The displacement of the arms, under the effect of the displacement of the weights 40, 41 subjected to gravity, occurs between a rest position of the device and a correction position of the device, each arm allowing a distinct correction depending on the position of the watch.

[0030] Thus, depending on the position of the watch movement 2 in space, the weights 40, 41, freely subjected to gravity, can move in their plane and cause a displacement of the arms 60, 61. The displacement of the weights 40, 41 makes it possible to act simultaneously on the means of modifying the active length of the balance spring 5, and thus to continuously adjust the active length of the balance spring in order to compensate for the disturbances of the isochronism of the balance wheel due to gravity.

[0031] In the preferred embodiment in which the device 6 includes two cams 30, 31 for driving the arms 60, 61, the cams are fixed to the shaft 20 and are respectively each in contact with the free end 600, 610 of the arms 60, 61. The position of the cams relative to each other is variable depending on the correction to be made on the spiral, the cams being able to be angularly offset from each other, just as they can be in an identical position.

[0032] Preferably, each cam 30, 31 is a radial cam with an external profile. Although radial cams with a substantially rectangular external profile are shown on the figures 1 to 3In practice, the shape envisaged for the external profile of each 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, and as shown in the figures 3 and 4, in the rest position of the adjusting device 6, a flat portion of each cam is in contact with an arm 60, 61, while in the correction position of the device 6, a corner or angle of the cam 30, 31 is in contact with the arm 60, 61. Preferably, even more so, as can be seen on the Figures 1 , 3 and 4, each cam 30, 31 is in contact with its respective arm 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 weights 40,41, freely subjected to gravity, can slide in their plane and cause a displacement of the arms 60, 61. In doing so, the displacement of the weights makes it possible to act simultaneously on the means of modifying the active length of the balance spring 5, allowing the active length of the balance spring to be continuously adjusted in order to compensate for the disturbances of the isochronism of the balance wheel due to gravity.

[0034] The movement of the weights 40, 41 causes a rotation of the shaft 20 via the cooperation of the toothed sectors 402, 412 with the pinions 20, 21 of the shaft 20 and has the effect of driving the cams 30, 31 which are fixed to the shaft, the cams then acting on the free end 600, 610 of the arms 60, 61 and moving at least one of the arms 60, 61 so that the second end of one of the arms comes into contact with the spiral 5 in order to modify the active length of the spiral 5.

[0035] Once the weight has stabilized following its change of position, the device will return itself to the rest position thanks to the action of the spring blades 520, 521 on the weights 40, 41.

[0036] 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.

[0037] 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. A self-contained device (6) for setting the active length of a balance spring (5), for an oscillator (4, 5) such as a sprung balance, comprising a balance cock (12) designed to be fitted on a plate (13) in a horology movement (2) and in which a balance staff can pivot, the balance spring (5) comprising an internal end designed to be attached to the balance staff and an external end attached to a stud (8) secured to a balance spring stud holder (10), the balance spring stud holder (10) being fitted so as to pivot on the cock (12) concentrically with the balance staff, and means for changing the active length of the balance spring (5), in which the means for changing the active length of the balance spring comprise: - a first arm (60) which can move between a locked position and a correction position of the device, the at least first arm (60) having a first free end (600) and a second end (601) engaging with a first pair of pins (19) fastened to the balance spring stud holder (10), the first pair of pins (19) being angularly offset relative to the stud (9); characterised in that comprises: - a second arm (61) which can move between a locked position and a correction position of the device, the second arm having a first free end (610) and a second end (611) engaging with a second pair of pins (19') fastened to the balance spring stud holder (10), the second pair of pins being angularly offset relative to the first pair of pins; - resilient biasing means (62, 63, 64, 65) configured to exert a resilient return-to-position action on the arms (60, 61); - two inertia blocks (40, 41), each of which is translationally mobile in orthogonal planes, the inertia blocks being arranged to be translationally displaced by gravity, the displacement of at least one of the inertia blocks (40, 41) rotationally driving a arbor (20) on which a first cam (30) is fitted, the rotation of the first cam (30) causing a displacement of the first arm (60) to act on the balance spring and simultaneously change the active length of the balance spring (5), and a second cam (31) arranged to engage with the second arm (61) and translationally displace it to act on the balance spring and simultaneously change the active length of the balance spring (5); - resilient return means (520, 521) configured to exert a resilient return-to-position action on the inertia blocks (40, 41).

2. The self-contained device (6) for setting the active length of a balance spring (5) according to claim 1, characterised in that each inertia block comprises a toothed sector arranged to engage with a pinion secured to the axis (30).

3. The self-contained device (6) for setting the active length of a balance spring (5) according to claim 2, characterised in that the resilient return means are in the form of a pair of leaf springs (520, 521) arranged at each end of each inertia block (40, 41).

4. The self-contained device (6) for setting the active length of a balance spring (5) according to claim 1 or 3, characterised in that the cams (30, 31) are radial cams with an external profile.

5. The self-contained device (6) for setting the active length of a balance spring (5) according to claim 1 or 3, characterised in that the cams (30, 31) are angularly offset relative to each other.

6. The self-contained device (6) for setting the active length of a balance spring (5) according to any of claims 1 to 5, characterised in that, when the device (6) is in the locked position, a planar portion of each of the cams (30, 31) is in contact with the arm (60, 61) with which it engages, and, in the correction position of the device (6), a corner or an angle of each of the cams (30, 31) is in contact with the arm (60, 61) with which it engages.

7. The self-contained device (6) for setting the active length of a balance spring (5) according to any of claims 1 to 6, characterised in that the cams (30, 31) are in permanent contact with the free end (600, 610) of each arm (60, 61) regardless of the position of the inertia block (40, 41).

8. The self-contained device (6) for setting the active length of a balance spring (5) according to any of the preceding claims, characterised in that the free end (600) of the first arm (60) comprises elastically-deformable setting means, the setting means being in the form of a leaf spring with its first end secured to the arm and another end free, the free end being arranged so as to be biased and set the length of the first arm (60).

9. The self-contained device (6) for setting the active length of a balance spring (5) according to any of claims 1 to 8, characterised in that the free end (610) of the second arm (61) comprises elastically-deformable setting means, the setting means being in the form of a leaf spring with its first end secured to the arm and another end free, the free end being arranged so as to be biased and set the length of the second arm (61).

10. The self-contained device (6) for setting the active length of a balance spring (5) according to claim 8 or 9, characterised in that it comprises means for setting the elastic stress, the setting means being in the form of a screw, the screw running through the free end and bearing against the arm.

11. The self-contained device (6) for setting the active length of a balance spring (5) according to any of the preceding claims, characterised in that the first pair of pins (19) is fastened to the balance spring stud holder (10) via a first support (8'), the first arm (60) being arranged so that it slides between the first two pins (19) and comes into contact with the outer coil of the balance spring in the correction position.

12. The self-contained device (6) for setting the active length of a balance spring (5) according to any of the preceding claims, characterised in that the second pair of pins (19') is fastened to the balance spring stud holder (10) via a second support (8"), the second arm (61) being arranged so that it runs between the two first pins (19) and comes into contact with the outer coil of the balance spring in the correction position.

13. The self-contained device (6) for setting the active length of a balance spring (5) according to any of the preceding claims, characterised in that the inertia blocks (40, 41) are parallelepipedal in shape.

14. A horology movement (2) comprising a balance-spring-type oscillator (4, 5) and a self-contained device (6) for setting the active length of the balance spring (5), characterised in that the self-contained setting device (6) is according to any of the preceding claims.

15. A timepiece (1) comprising a horology movement (2), characterised in that the horology movement (2) is according to claim 14.

Images