REGULATOR ORGAN FOR CLOCK, INCLUDING A RETURN DEVICE EQUIPPED WITH LOCKING METHOD

Description

Technical field of the invention

[0001] The invention relates to the field of watchmaking, and more particularly to the field of mechanical watchmaking, where the regulation of driving energy is provided by a regulating organ. More specifically, the invention relates to a regulating organ equipped with a precision regulator system, a watch movement comprising such a regulating organ, and a timepiece comprising such a watch movement. 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 pallets that engage the teeth of an escape wheel. Thus engaged, the escape wheel is imparted a step-by-step rotational movement whose frequency is determined by the anchor's oscillation frequency, itself synchronized with the balance wheel's oscillation frequency.

[0005] In 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.

[0006] It is known to regulate the course of the balance wheel by adjusting the active length of the balance spring, defined as the curvilinear length between its inner end and a counting point, located in the vicinity of the outer end of the balance spring and generally defined by a pair of stops carried by a key mounted on a rack system.

[0007] In operation, this regulator system is fixed in rotation relative to the axis of the balance spring. However, it is possible, by manual intervention, to finely adjust its angular position, e.g. by pivoting, using a screwdriver, an eccentric that acts on the regulator system in the manner of a cam.

[0008] The assembly comprising the bridge, the regulator system, the key, the stud holder, the stud, the arbor, the spring, and the balance wheel is commonly referred to as the "regulating organ." Examples of regulating organs are provided by European patent EP3304215 and European patent EP 2 876 504, both in the name of the watch manufacturer ETA.

[0009] Some racket systems feature a stud holder to which the outer end of the balance spring is attached, and the racket system key allows for some play to permit the spring to move between two stops. However, the chronometric properties, particularly anisochronism, are highly sensitive to play in the racket key, which is difficult to control precisely.

[0010] In some mechanisms, the stops are adjustable to tighten the balance spring and eliminate play, particularly during its operation. In this case, the rate is first set by moving the regulator key, then the balance spring is tightened with the key. However, tightening the balance spring with the regulator key risks putting stress on it and creating chronometric errors, notably by misaligning the coils. Furthermore, eliminating the play also alters the rate, and once the balance spring is tightened, the regulator key cannot be moved along the spring to fine-tune the rate.

[0011] Other balance springs incorporate an integrated regulating device. In these balance springs, the rate is not regulated by changing the effective length of the balance spring, but by applying a force or torque to an elastic element arranged in series with the balance spring. This allows the stiffness of the elastic element, and consequently of the balance spring as a whole, to be modified. Adjusting the stiffness of the balance spring allows the rate of the regulating organ to be regulated. Such a balance spring with an elastic element is described, for example, in patent application EP4009115.

[0012] However, in these cases, standard regulator systems cannot be used because they are incompatible with the balance spring adjustment mechanism. Furthermore, since very fine adjustments are required, it is essential that there be no play between the balance spring and its points of interaction with the regulator. Otherwise, the rate could be altered in the event of a shock if the balance spring does not return to its exact position afterward. There are also systems where the stud holder comprises two parts, one movable relative to the other fixed, as disclosed in document CH521620A.

[0013] Furthermore, it is necessary to be able to adjust the regulating organ's rate without changing the reference mark. Indeed, when the regulating organ is mounted in the movement, the reference mark is set so that the balance wheel cooperates correctly with the pallet fork. Once the reference mark is set, it is important to avoid misaligning it, especially when adjusting the regulating organ's rate. Summary of the invention

[0014] The aim of the present invention is to overcome all or part of the aforementioned disadvantages by proposing a racket system compatible with this type of adjustment device.

[0015] For this purpose, the invention relates to a regulating device according to the terms of the attached claim 1.

[0016] The invention is remarkable in that the regulating organ includes locking means configured to lock the second part of the stud holder in a position relative to a movement plate.

[0017] Thanks to the invention, the second part of the pin holder can be locked after the reference mark has been set, thus preventing it from being misaligned, for example when the first part is operated to adjust the operation of the regulating organ.

[0018] According to a particular embodiment of the invention, the locking means comprise an eccentric mounted on a balance bridge of the regulating organ.

[0019] According to a particular embodiment of the invention, the second part comprises a protuberance having the shape of a circular arc cooperating with the eccentric.

[0020] According to a particular embodiment of the invention, the locking means comprise a locking plate and a locking screw for assembling the locking plate onto the second part and locking its position.

[0021] According to a particular embodiment of the invention, the locking plate has a shape cooperating on one side with a balance bridge of the regulating member, and on the other side with a bearing of the regulating member to block the second part.

[0022] According to a particular embodiment of the invention, the locking screw is arranged to pass through the locking plate to be screwed into a balance bridge of the regulating organ.

[0023] According to a particular embodiment of the invention, the racket system includes a spring, exerting a force between the first part and the second part to hold the arm of the first part against the cam.

[0024] According to a particular embodiment of the invention, the spiral spring comprises a wound ribbon and means for adjusting the stiffness of the spiral spring having an elastic element arranged in series with the wound ribbon, the pin holder being mechanically linked to the elastic element.

[0025] According to a particular embodiment of the invention, the adjustment means include pre-stressing means for applying a variable force or torque to the flexible element.

[0026] According to a particular embodiment of the invention, the first part comprises a first eyelet and the second part a second eyelet, the elastic element and the prestressing means being arranged between the first eyelet and the second eyelet, the first eyelet being movable relative to the second eyelet to actuate the prestressing means, the displacement of the first eyelet modifying the stiffness of the spiral spring.

[0027] According to a particular embodiment of the invention, the prestressing means comprise a lever connected to the flexible element, the first pin being integral with a free end of the lever.

[0028] According to a particular embodiment of the invention, the prestressing means comprise a semi-rigid structure arranged in parallel with the flexible element, the lever being connected to the semi-rigid structure.

[0029] According to a particular embodiment of the invention, the flexible element is linked to a rigid support, the second eyelet being fixed to the rigid support.

[0030] According to a particular embodiment of the invention, the first part and the second part are superimposed.

[0031] According to a particular embodiment of the invention, the first part is mobile in rotation relative to the second part.

[0032] The invention also relates to a clockwork mechanism comprising such a regulating organ.

[0033] The invention also relates to a timepiece, for example a watch, comprising such a timepiece movement. Brief description of the figures

[0034] The aims, advantages and features of the present invention will become apparent from the reading of several embodiments given solely by way of non-limiting examples, with reference to the accompanying drawings in which: there figure 1 schematically represents a perspective view of a regulating organ according to an embodiment of the invention, the regulating organ being arranged in a clockwork movement, the figure 2 schematically represents a perspective view of part of the first embodiment of the regulating organ of the figure 1 , without a balancing bridge and without a racket system, the figure 3schematically represents a top view of a spiral spring of the regulating organ, the figure 4 schematically represents a perspective view of part of a regulating organ according to a second embodiment of the invention, the regulating organ being arranged in a clockwork movement, the figure 5 schematically represents a perspective view of the second embodiment of the regulating organ of the figure 4 , there figure 6 schematically represents a perspective view of a variant of the eyelet holder of the second embodiment, the figure 7 schematically represents a perspective view of the second part of the piton holder of the variant of the figure 6 , and the figure 8 schematically represents a perspective view of the second part of the eyelet holder mounted on a balancing bridge. Detailed description of the invention

[0035] THE figures 1 and 2show a schematic representation of a first embodiment of a regulating organ 1 arranged in a clockwork movement 10. The clockwork movement 10 includes a plate 21, a regulating organ equipped with an inertial mass, and an elastic return element for the inertial mass configured to make it oscillate.

[0036] The regulating organ 1 further includes a racket system 20, an annular balance wheel 23 as an inertial mass, a balance shaft 24, a balance spring 25 as an elastic return element, and a balance bridge 22.

[0037] The plate 21 is provided with a housing 26 to receive the regulating organ 1, in which are superimposed, here from bottom to top, the balance wheel 23, the balance spring 25, the balance bridge 22 and the regulator system 20.

[0038] The balance staff 24 is centered in the housing 26 and passes through the center of the balance wheel 23, the balance spring 25, and the balance bridge 22. The balance staff 24 is held by two shock-absorbing bearings 28 arranged at its two ends. The first bearing is located at the bottom of the housing 26, and the second bearing 28 is located above the housing 26 and is held by the balance bridge 22. The balance bridge 22 passes through the top of the housing 26 via the central axis of the housing 26. The balance bridge 22 has a through hole in which the second bearing 28 is held. The regulator system 20 is mounted on the balance bridge 22 and, in this embodiment, is located on the central axis of the housing 26.

[0039] Represented on the figures 2 And 3The balance spring 25 preferably extends substantially in a plane. The balance spring 25 comprises a flexible ribbon 2 wound upon itself in several turns, the ribbon 2 having a predetermined stiffness. The inner end 9 of the ribbon 2 is made of material or is assembled to a support 3, generally called a ferrule. The support 3 has a substantially triangular shape and is threaded around the balance staff 24.

[0040] The balance spring 25 also includes means for adjusting its stiffness. For example, these adjustment means can be operated by a user when the regulating organ is mounted on the movement's mainplate.

[0041] The adjustment means comprise a flexible element 5 arranged in series with the ribbon 2, the flexible element 5 connecting one end 4, 9 of said ribbon 2 to a rigid support 17, and fixed to one of the ends 4, 9 of the ribbon 2. The flexible element 5 is fixed to the outer end 4 of the ribbon 2. The elastic element 5 is a different element from the ribbon 2.

[0042] The flexible element 5 adds additional stiffness to that of the ribbon 2. The flexible element 5 preferably has a stiffness greater than that of the ribbon 2. The flexible element 5 is arranged here in the extension of the ribbon 2. Preferably, the adjustment means and the ribbon 2 are monoblocs, or even formed of the same material, for example silicon.

[0043] The flexible element 5 of the spiral spring 25 includes a pivot with uncrossed flexible leaves. The pivot comprises two uncrossed flexible leaves 11, 12 and a rigid part 18. The flexible leaves 11, 12 are joined, on one side laterally to a rigid support 17, and on the other side to the rigid part 18 by bringing them closer together. Preferably, the flexible blades 11, 12 extend from the rigid part 18 to the rigid support 17. The outer end 4 of the ribbon 2 is joined to the rigid part 18. The rigid support 17 is stationary relative to the plate 21. The rigid support 17 has an L-shape, the first arm 46 of the L serving as a link with the flexible blades 11, 12, the second arm 47 of the L being oriented on the opposite side of the pivot with uncrossed blades so that it can be assembled to the clock movement 10.

[0044] The means for adjusting the spiral spring 25 further include preload means 6 for applying a variable force or torque to the flexible element 5. This allows the stiffness of the spiral spring to be adjusted. The torque or force is continuously adjustable by the preload means 6. In other words, the torque or force is not restricted to specific values. Therefore, the stiffness of the flexible element 5 can be adjusted with high precision.

[0045] The prestressing means 6 comprise a secondary flexible blade 19, arranged on an opposite side of the rigid part 18 in line with the pivot with crossed blades. The secondary flexible blade 19 is positioned tangentially to the band 2, at the outer end 4.

[0046] The secondary flexible blade 19 is connected at the other end to a curved lever 14 which bypasses the ribbon 2. The lever 14 is connected, in addition to the secondary flexible blade 19, to a semi-rigid structure 27 linked to the rigid support 17. The semi-rigid structure 27 deforms in part when the lever 14 is actuated by force or torque.

[0047] The force or torque is exerted on the free end 15 of the lever 14. Thus, the lever 14 of the preload means 6 transmits the force or torque to the flexible element 5 via the secondary flexible blade 19 and the semi-rigid structure 27, so as to modify the stiffness of the spiral spring 25.

[0048] In order to be able to apply the variable force or torque on the spiral spring 25, the regulating member includes a particular racket system 20 according to the invention.

[0049] In the first embodiment of figures 1 and 2The snowshoe system 20 is equipped with a two-part piton holder 31, a first part 32 and a second part 33. The first part 32 of the piton holder 31 suspends the first piton 34, while a second part 33 of the piton holder 31 is equipped with the second piton 35. The piton holder 31 is mechanically linked to the elastic element 5, but it does not block the tape 2.

[0050] The first part 32 of the stud holder 31 is arranged partly above the second part 33 of the stud holder 31, which is in contact with the balance bridge 22. The two parts of the stud holder 31 are held and positioned by the shock absorber 28.

[0051] The racket system 20 includes two eccentrics 36, 37. The first eccentric 36 is mounted on the second part 33 of the piton holder 31 and allows angular adjustment between the two parts of the piton holder 31, which allows adjustment of the step.

[0052] According to the invention, the regulating organ 1 further comprises locking means configured to lock the second part 33 of the stud holder 31 in a position, here angular, relative to the movement plate 21. The locking means comprise the second eccentric 37.

[0053] The second eccentric 37 is mounted on the balance bridge 22 and allows the angular position of the stud holder 31 to be adjusted relative to the plate 21, which allows the reference mark to be adjusted.

[0054] Thus, during the assembly of the racket system 20, the second part 33 of the pin holder 31, which is movable, is first positioned and then locked in place by the second eccentric 37 so that it remains stationary relative to the plate 21. Next, the first part 32 of the pin holder 31 is positioned and then angularly locked by the first eccentric 36 so that it remains stationary relative to the second part 33. Consequently, by actuating the second eccentric 37, the entire pin holder 31 rotates around the axis of the balance wheel to adjust the reference mark. To unlock and move the first part 32, the first eccentric 36 is actuated. In this case, only the first part 32 of the pin holder 31 rotates around the axis of the balance wheel, which allows the first pin 34 to be moved and the elastic element 5 to be acted upon to vary the rate.

[0055] Therefore, only the first part 32 of the eyelet holder 31 is mobile relative to the rocker bridge 22 after assembly, in order to be able to move the first eyelet 34 and act on the elastic element 5.

[0056] The two parts 32, 33 surround the second level 28. For this, each part 32, 33 includes a central ring 38, 39 arranged around the second level 28, the two central rings 38, 39 being superimposed.

[0057] The first part 32 comprises two protrusions 41, 42 extending radially from the central ring 38, a first protrusion 41 holding the first pin 34 downwards in the housing 26 by means of a first screw 74, the second protrusion 42 having an arc-shaped form cooperating with the first eccentric 36.

[0058] The second part 33 comprises three protrusions 43, 44, 45 extending from the central ring 39. A first protrusion 43 holds the second pin 35 downwards in the housing 26 by means of a second screw 75, a second protrusion 44 extending around the first eccentric 36, and the third protrusion 45 having an arc-shaped form cooperating with the second eccentric 37.

[0059] In a reference arrangement, the first stud 34 and the second stud 35 are, for example, arranged in a substantially symmetrical manner with respect to the shaft of the rocker arm 24.

[0060] The first pin 34 cooperates with the free end 15 of the lever 14, and the second pin 35 cooperates with the second arm 47 of the rigid support 17. Thus, the prestressing means 6 and the elastic element 5 are supported by the racket system 20 from which they are suspended.

[0061] The two pins 34, 35 are arranged on either side of the prestressing means 6 and the elastic element 5. In addition, the two pins 34, 35 are rigidly connected to the lever 14 and the rigid support 17. In other words, the first 34 and the second pin 35 are respectively fixed to the lever 14 by the free end 15 and to the rigid support 17 by the second arm 47. The assembly of the pins and the spiral spring 25 is carried out, for example, by gluing, brazing, welding, by deformation of metallic glass, or by mechanical fastening.

[0062] The first peg 34 is movable relative to the second peg 35. To this end, the first part 32 is movable relative to the second part 33. The first part 32 is movable in rotation around the second bearing 28. Thus, the first peg 34 moves with the first part 32, the first peg 34 being movable in rotation around the second bearing 28. The first peg 34 can, for example, be moved over an angular range of 20°, or even 10°.

[0063] The displacement of the first pin 34 relative to the second pin 35 modifies the stiffness of the elastic element 5, because the displacement exerts a greater or lesser force or torque on the lever 14 of the preload means 6, so that the stiffness of the elastic element 5 varies, and thus the stiffness of the entire spiral spring 25. The ratchet system 20 thus allows adjustment of the operation of the regulating member 1.

[0064] To this end, the racket system 20 allows the position of the first peg 34 to be changed relative to the second peg 35 by means of the second arc-shaped protrusion 42 of the first part 32 and the first eccentric 36. The arc has a diameter only slightly smaller than the head of the first eccentric 36, so that the movement of the first eccentric 36 causes the second protrusion 42, and therefore the first part 32 relative to the second part 33, to move circularly around the second bearing 28, while the second part 33 remains in position when the first part 32 is actuated. Thus, by rotating the first eccentric 36, the second arc-shaped protrusion 42 moves circularly around the second bearing 28.The first part 32 moves relative to the second part 33, and consequently, the first pin 34 moves relative to the second pin 35 to modify the force or torque applied to the preload means 6 of the spiral spring 25. The absence of play between the eccentrics 36, 37 and the arcs of circles 42, 45 allows for adjustment without hysteresis.

[0065] Adjustment marks 29 are arranged on the second protuberance 42 in the shape of an arc of a circle around the first eccentric 36. Thus, to adjust the racket system 20, the first eccentric 36 is oriented according to a preferred reference.

[0066] The racket system 20 is configured to adjust the operation of the regulating organ 1 with a resolution of 1 second per day or less, preferably 0.5 seconds per day or less, or even 0.1 seconds per day or less. Thus, the racket system 20 is calibrated so that its actuation allows for such resolution. The configuration of the regulating organ 1 enables this level of precision.

[0067] Preferably, the adjustment marks 29 correspond to the resolution. In other words, the difference between two consecutive marks corresponds to 1 second, 0.5 seconds, or even 0.1 seconds per day.

[0068] In the second embodiment of the regulating organ 40 of the Figures 4 and 5 , the characteristics of the regulating organ 40 are substantially identical to the first embodiment, except for the adjustment of the racket system 60.

[0069] The first part 52 of the racket system 60 includes an arm 63 extending radially outwards from the first part 52 in the same plane. The second part 53 does not include the arc-shaped protrusion.

[0070] The racket system 60 includes a rotating cam 55 in place of the first eccentric. The cam 55 cooperates with the arm 63 of the first part 52 to rotate it around the second bearing 28. The end 56 of the arm 63 is preferably constantly in contact with the cam 55, so that the rotation of the cam 55 causes a displacement on the arm 63 according to the angular position of the cam 55. Thus, the first part 52 of the racket system 60 moves in a manner similar to the first embodiment. Such a racket system 60 with a cam 55 allows the stiffness of the spiral spring 25 to be varied linearly.

[0071] To keep the arm 63 of the first part 52 in contact with the cam 55, the racket system 60 includes a spring 57 exerting a restoring force on the first part 52. The spring 57 is substantially U-shaped surrounding a locking screw 77, one end 58 of the U being assembled to the second part 53 of the racket system 20, and a second end 59 of the U being retained by a retaining hook 61 arranged on the first part 52. The spring 57 is arranged on the second part of the stud holder 31 symmetrically to the cam 55 with respect to the second bearing 28.

[0072] Thus, the spring 57 exerts a restoring force on the two parts 52, 53 of the racket system 60, the restoring force having the function of keeping the arm 63 of the first part 52 constantly in contact with the cam 55. When the cam 55 is acted upon, the first part 52 rotates to move the first peg 34 relative to the second peg 35, while undergoing a restoring force exerted by the spring 57, to allow the contact of the arm 63 of the first part 52 against the cam 55, in particular when the peripheral wall 64 of the cam 55 moves away from the arm 63.

[0073] The 60-meter racket system is configured to adjust the rate of the 40-meter regulating organ with a resolution of 1 second per day or less, preferably 0.5 seconds per day or less, or even 0.1 seconds per day or less. The configuration of the 40-meter regulating organ allows for such precision.

[0074] According to the invention, the regulating organ 40 further comprises locking means configured to lock the second part 53 of the stud holder 51 in a position relative to the balance bridge 22 of the movement. The locking means comprise a locking plate 62 and a locking screw 77 for assembling the locking plate 62 onto the second part 53 and locking it into position.

[0075] Preferably, the locking plate has a shape cooperating on one side with a balance bridge 72 and on the other side with the second bearing 28. The locking screw 77 passes through the locking plate 62 to be screwed into the balance bridge 72 arranged below the locking plate 62. Thus, by tightening the locking screw 77, the locking plate 62 exerts a force at least in part on the second part 53 of the stud holder 51, at the level of a shoe 78 of the first end 58 of the U of the spring 57, the shoe resting on the second part 53 of the stud holder 51.

[0076] Thus, during the assembly of the racket system 20, the second part 53 of the pin holder 51, which is mobile, is first positioned, then it is locked by means of the locking plate 62 and the locking screw 77 so that it remains immobile relative to the balance bridge 72. Only the first part 52 remains mobile relative to the balance bridge 72 after assembly, in order to be able to move the first pin 34 and act on the elastic element 5.

[0077] Adjustment marks 49 are also located on the cam 55. Thus, to adjust the racket system 60, the cam 55 is moved, for example by means of an adjustment knob (not shown in the diagrams). Figures 4 and 5 ), positioned on the cam 55, and which can be rotated. Thus, to adjust the racket system 60, the cam 55 is oriented according to a preferred reference point.

[0078] Preferably, the 49 adjustment marks correspond to the resolution. In other words, the difference between two consecutive marks allows the rate to be adjusted by one second, 0.5 seconds, or even 0.1 seconds per day. On the figure 6 , the resolution of adjustment marks 49 is 0.1 seconds.

[0079] On the Figures 6 and 7 The stud holder 51 is a variant of the second embodiment, in which the second part 53 comprises, on one side, a bent arm 70, and on the other side, a pair of fingers 71, as well as a substantially circular through-hole 68 in the middle. The bent arm 70 functions to cooperate with the locking plate 62. The pair of fingers 71 functions to hold the axis of the cam 55 and to rest on the balance bridge 72 of the movement.

[0080] The through-hole 68 allows the insertion of a shock-absorbing bearing 28 of the balance wheel, around which the stud holder 51 is mounted and held. The through-hole 68 is opened by a slot 69 to provide flexibility to a segment 73 bordering the hole 68. Thus, the bearing 28 can be clipped and held in the hole 68. Thanks to this flexibility, the segment 73 can move apart to insert the bearing 28 into the hole 68 and exert sufficient force to hold it. The shapes of the hole 68 and the shock-absorbing bearing 28 are configured to cooperate, the shape of the bearing 28 preferably being slightly larger than the shape of the hole 68.

[0081] In addition, the geometry of the orifice 68 allows the pin carrier 51 to be guided in rotation. Indeed, the flexible segment 73 allows the pin carrier 51 to be guided in rotation around the shock absorber bearing while maintaining the concentricity of the balance shaft axis (not shown in the figures).

[0082] On the figure 6 , a rotary adjustment knob 65 is mounted on the cam 55, the knob 65 having peripheral adjustment marks 66, the adjustment marks 66 being in accordance with the invention.

[0083] There figure 8 This shows how the locking means secure the second part 53 of the stud holder 51 to the balance bridge 72. The locking plate 62 presses against the bent arm 70 to clamp it against the balance bridge 72. The locking screw 77 passes through the locking plate 62 and inside the bent arm 70 to reach the balance bridge 72 located below. Thus, the second part 53 of the stud holder 51 is sandwiched between the locking plate 62 and the balance bridge 72. In addition, the locking plate 62 retains the spring 57.

[0084] Naturally, the invention is not limited to the embodiments of regulating organs described with reference to the figures, and variants could be envisaged without departing from the scope of the invention.

Claims

1. A regulating organ (1, 40) for a horology movement comprising an inertial mass, for example a balance (23), a balance spring (25), and an index assembly system (20, 60) for setting the rate of the balance spring (25), the balance spring (25) comprising a coiled strip (2) and means (30, 50) for adjusting the stiffness of the balance spring provided with a flexible element (5) arranged in series with the coiled strip (2), the adjustment means (30, 50) comprising pre-tensioning means (6) for applying a variable force or couple to the flexible element (5), the index-assembly system (20, 60) comprising a stud holder (31, 51) mechanically connected to the flexible element (5), the stud holder (31, 51) comprising a first part (32, 52) and a second part (33, 53), the first part (32, 52) being mobile relative to the second part (33, 53) to be able to set the rate of the regulating organ (1, 40), the first part (32, 52) comprising a first balance spring stud (34) and the second part (33, 53) comprising a second balance spring stud (35), the flexible element (5) and the pre-tensioning means (6) being arranged between the first balance spring stud (34) and the second balance spring stud (35), the first balance spring stud (34) being mobile relative to the second balance spring stud (35) to actuate the pre-tensioning means (6), the movement of the first balance spring stud (34) changing the stiffness of the balance spring, the regulating organ (1, 40) comprising bolting means configured to lock the second part (33) of the stud holder (31, 51) in a position relative to a plate (21) in the movement.

2. The regulating organ according to claim 1, characterised in that the bolting means comprise an eccentric (37) mounted on a balance cock (22) on the regulating organ (1).

3. The regulating organ according to claim 2, characterised in that the second part (33) comprises a protrusion (45) in the shape of a circular arc engaging with the eccentric (37).

4. The regulating organ according to claim 1, characterised in that the bolting means comprise a bolting plate (62) and a bolting screw (77) for assembling the bolting plate (62) to the second part (53) and bolting its position.

5. The regulating organ according to claim 4, characterised in that the bolting plate (62) has a shape cooperating on one side with a balance cock (72) on the regulating organ (40), and on the other side with a bearing (28) on the regulating organ to lock the second part (33).

6. The regulating organ according to claim 4 or 5, characterised in that the bolting screw (77) is arranged to cross the bolting plate (62) so as to be screwed in a balance cock (72) on the regulating organ (40).

7. The regulating organ according to any of the preceding claims, characterised in that the index-assembly system (60) comprises a spring (57) exerting a force between the first part (52) and the second part (53) to hold the arm (63) on the first part (52) against a cam (55).

8. The regulating organ according to any of the preceding claims, characterised in that the pre-tensioning means (6) comprise a lever (14) connected to the flexible element (5), the first balance spring stud being secured to a free end (15) of the lever (14).

9. The regulating organ according to claim 8, characterised in that the pre-tensioning means (6) comprise a semi-rigid structure arranged parallel to the flexible element (5), the lever (14) being connected to the semi-rigid structure.

10. The regulating organ according to any of the preceding claims, characterised in that the flexible element (5) is connected to a rigid support (17), the second balance spring stud (35) being secured to the rigid support (17).

11. The regulating organ according to any of the preceding claims, characterised in that the first part (32, 52) and the second part (33, 53) are superimposed.

12. The regulating organ according to any of the preceding claims, characterised in that the first part (32, 52) is rotationally mobile relative to the second part (33, 53).

13. A horology movement, characterised in that it comprises a regulating organ (1, 40) according to any of the preceding claims.

14. A timepiece, for example a watch, characterised in that it comprises a horology movement according to claim 13.