CH721296A2 - Regulating organ of a clockwork comprising an actuation system fitted with an eccentric - Google Patents

Abstract

The invention relates to a regulating member (1) for a watch movement comprising an inertial mass, for example a balance (23), a balance spring (25), a balance bridge (22) and an actuation system (20) for adjusting the rate of the balance spring (25), the balance spring (25) comprising a wound ribbon and means (30) for adjusting the stiffness of the balance spring provided with an elastic element arranged in series with the wound ribbon, the adjustment means (30) comprising pre-stressing means for applying a variable force or torque to the flexible element, the actuation system (20) comprising an eccentric actuating the pre-stressing means of the adjustment means (30). The invention also relates to a watch movement comprising such a regulating member (1) as well as to a timepiece, for example a watch, comprising said watch movement.

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 the driving energy is carried out by a regulating organ. The invention relates, more specifically, to a regulating organ provided with a precision actuation system, for adjusting the rate of the balance spring, and a timepiece movement comprising such a regulating organ, as well as a timepiece comprising such a timepiece movement.

Technological background

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

[0003] By an internal end, the balance spring is fixed to a shaft integral in rotation with the balance wheel; by an external end, the balance spring is fixed to a stud mounted on a stud holder itself integral with a fixed bridge (or balance cock).

[0004] The rotation of the balance wheel is maintained - and its oscillations counted - by an escapement mechanism comprising an anchor driven by a low-amplitude oscillating movement, provided with two pallets which engage the teeth of an escape wheel. Thus engaged, the escape wheel is subjected to a step-by-step rotational movement whose frequency is determined by the oscillation frequency of the anchor, itself set to the oscillation frequency of the sprung balance).

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

[0006] It is known to adjust the rate of the balance spring by adjusting the active length of the balance spring, defined as the curvilinear length between its internal end and a counting point, located in the vicinity of the external end of the balance spring and generally defined by a pair of stops carried by a key mounted on a counter-balance system.

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

[0008] The assembly comprising the bridge, the index 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 by European patent EP 2 876 504, both in the name of the watch manufacturer ETA.

[0009] There are indexing systems comprising a stud holder to which an external end of the balance spring is fixed, and whose indexing system key leaves a clearance to allow the balance spring to move between the two stops. However, the chronometric properties, in particular the isochronism, are very sensitive to the play in the balance spring key, while this play is difficult to control precisely.

[0010] In some devices, the stops are adjustable to tighten the hairspring in order to eliminate play, particularly during operation of the hairspring. In this case, the rate is first adjusted by moving the index key, then the hairspring is tightened with the key. But tightening the hairspring with the index key risks constraining it, and creating timekeeping defects, in particular by off-centering of the coils. In addition, removing the play also modifies the rate, and once the hairspring is tightened, the index key can no longer be moved along the hairspring to finish finely adjusting the rate.

[0011] Other hairsprings have an integrated adjustment device. In these hairsprings, the rate is not adjusted by changing the effective length of the hairspring, but by applying a force or torque to an elastic element arranged in series with the hairspring. It is thus possible to change the stiffness of the elastic element and consequently of the hairspring as a whole. Adjusting the stiffness of the hairspring makes it possible to adjust the rate of the regulating member. Such a hairspring provided with an elastic element is for example described in patent application EP4009115.

[0012] However, in these cases, the usual indexing systems cannot be used, because they are not compatible with the balance spring adjustment device. In addition, since the rate must be adjusted very finely, it is essential that there is no play between the balance spring and its areas of interaction with the indexing. Indeed, otherwise, there is a risk of modifying the rate in the event of an impact, if the balance spring does not reposition itself in exactly the same way after the impact.

Summary of the invention

[0013] The aim of the present invention is to overcome all or part of the drawbacks mentioned above by proposing an actuation system, in particular compatible with this type of adjustment device.

[0014] To this end, the invention relates to a regulating member for a watch movement comprising an inertial mass, for example a balance, a balance spring, a balance bridge, and an actuation system for adjusting the rate of the regulating member, the balance spring comprising a wound ribbon and means for adjusting the stiffness of the balance spring provided with an elastic element arranged in series with the wound ribbon, the adjustment means comprising prestressing means for applying a variable force or torque to the flexible element.

[0015] The invention is remarkable in that the actuation system comprises an eccentric actuating the prestressing means of the adjustment means.

[0016] Thanks to the invention, the rate of the regulating member can be adjusted simply by changing the position of the eccentric, because it acts on the prestressing means to adjust the rate of the regulating member.

[0017] According to a particular embodiment of the invention, the eccentric is arranged through the balance bridge, the eccentric being rotatably mounted.

[0018] According to a particular embodiment of the invention, the eccentric comprises a head and a main body extending from the head.

[0019] According to a particular embodiment of the invention, the body comprises a finger extending from the body, the finger being eccentric relative to the main axis of the main body of the eccentric.

[0020] According to a particular embodiment of the invention, the head comprises a hollow intended to receive the tip of a tool making it possible to actuate the eccentric.

[0021] According to a particular embodiment of the invention, the prestressing means comprise a first movable lever connected to the flexible element, the eccentric being in direct or indirect contact with the first lever in order to be able to actuate it.

[0022] According to a particular embodiment of the invention, the prestressing means comprise a second movable lever connected to the flexible element, the eccentric being in direct or indirect contact with the second lever in order to be able to actuate it.

[0023] According to a particular embodiment of the invention, the prestressing means comprise a movable body connected to the first lever and/or to the second lever, the finger being in contact with the movable body in order to be able to move it.

[0024] According to a particular embodiment of the invention, the finger comprises a peripheral groove cooperating with the movable body.

[0025] According to a particular embodiment of the invention, the actuation system comprises a stud holder comprising a stud on which the balance spring is mounted, the stud being mechanically linked to the elastic element of the balance spring.

[0026] According to a particular embodiment of the invention, the stud is mechanically linked to the elastic element.

[0027] According to a particular embodiment of the invention, the stud holder is arranged on the balance bridge around a bearing of the balance shaft.

[0028] The invention also relates to a clockwork movement comprising such a regulating organ.

[0029] The invention also relates to a timepiece, for example a watch, comprising such a timepiece movement.

Brief description of the figures

[0030] The aims, advantages and characteristics of the present invention will appear on reading several embodiments given solely as non-limiting examples, with reference to the appended drawings in which: – Figure 1 schematically represents a top view of a regulating member according to a first embodiment of the invention, – Figure 2 schematically represents a bottom view of the first embodiment of the regulating member of Figure 1, – Figure 3 schematically represents a side sectional view along section line III of the first embodiment of the regulating member of Figure 1, – Figure 4 schematically represents a disassembled perspective view of the first embodiment of the regulating member of Figure 1, and – Figure 5 schematically represents a top view of a spiral spring of the first embodiment of the regulating member of Figure 1.

Detailed description of the invention

[0031] Figures 1 to 5 show a schematic representation of a first embodiment of a regulating member 1, intended to be arranged in a timepiece movement, not shown in the figures. Such a timepiece movement comprises for example a plate provided with a housing for receiving the regulating member 1, the regulating member 1 being provided with an inertial mass, and an elastic return element of the inertial mass configured to make it oscillate.

[0032] The regulating member 1 further comprises an actuation system 20, an annular balance 23 as an inertial mass, a balance shaft 24, a balance spring 25 as an elastic return element, and a balance bridge 22.

[0033] In Figures 1 to 3, the balance wheel 23, the balance spring 25, the balance bridge 22 and the actuation system 20 are superimposed, here from bottom to top.

[0034] The balance shaft 24 is centered and passes through the center of the balance 23, the center of the balance spring 25, and the balance bridge 22. The balance shaft 24 is held by two shock-absorbing bearings 28 arranged at both ends of the balance shaft 24. A first bearing, not shown in the figures, is arranged under the balance 23 and the balance bridge 22, and the second bearing 28 is held by the balance bridge 22. The balance bridge 22 is provided with a hole, here a through hole, in which the second bearing 28 is held. The actuation system 20 is mounted on the balance bridge 22 and is arranged, in this embodiment, on the central axis of the balance shaft 24.

[0035] Shown in Figure 5, an example of a spiral spring 25 preferably extends substantially in one plane. The spiral spring 25 comprises a flexible ribbon 2 wound on itself in several turns, the ribbon 2 having a predefined stiffness. The inner end 9 of the ribbon 2 is made of material or is assembled to a support 3, generally called a collet. The support 3 has a substantially triangular shape, and is threaded around the balance shaft 24.

[0036] The spiral spring 25 further comprises means 30 for adjusting its stiffness. For example, the adjustment means 30 can in particular be actuated by a user when the regulating member is mounted on the plate of the watch movement.

[0037] The adjustment means 30 comprise a flexible element 5 arranged in series with the ribbon 2, the flexible element 5 connecting one end 4 of said ribbon 2 to a fixed support 53, and secured to one of the ends 4 of the ribbon 2. The flexible element 5 is secured to the external end 4 of the ribbon 2. The elastic element 5 is a different element from the ribbon 2.

[0038] The flexible element 5 adds additional stiffness following that of the strip 2. The flexible element 5 preferably has a stiffness greater than that of the strip 2. The flexible element 5 is here arranged in the extension of the strip 2. Preferably, the adjustment means and the strip 2 are in one piece, or even formed from the same material, for example silicon.

[0039] In this embodiment of the spiral spring, the flexible element 5 comprises two flexible parts 15, 16 each connecting the strip 2 to a fixed support 53.

[0040] The two flexible parts 15, 16 are arranged, one with respect to the other, by axial symmetry along an axis A of the spiral spring 25. In other words, the two flexible parts 15, 16 are positioned so as to be symmetrical with respect to said axis A.

[0041] On the one hand, the axis A passes substantially through the center O of the spiral spring, and on the other hand, the axis A passes, preferably, through the external end 4 of the ribbon 2.

[0042] Thus, the two flexible parts 15, 16 are arranged at the periphery of the spiral spring, so that the two flexible parts 15, 16 are arranged at the same distance from the center 0 of the spiral spring 25.

[0043] The two flexible parts 15, 16 are preferably arranged relative to each other in a “mirror” type position relative to the axis A. For this purpose, the two flexible parts 15, 16 are preferably substantially identical.

[0044] The flexible parts 15, 16 each comprise a curved flexible blade 55, preferably forming a semicircle, and extending from the end of the fixed support 53. Each curved flexible blade 55 is further connected to the external end 4 of the ribbon 2 by a main flexible blade 7. The main flexible blades 7 are here arranged in the extension of one another.

[0045] The fixed support 53 has the shape of a trapezoid open on the large side towards the external end 4 of the ribbon 2.

[0046] The spiral spring adjustment means 25 further comprise pre-stressing means 6 for applying a variable force or torque to the flexible element 5. Thus, the stiffness of the spiral spring can be adjusted. The torque or force is continuously adjustable by the pre-stressing means 6. In other words, the torque or force is not restricted to point values. Thus, the stiffness of the flexible element 5 can be adjusted with great precision.

[0047] Preferably, the prestressing means 6 apply a substantially identical force or torque to each flexible part 15, 16. The directions of the forces are preferably substantially symmetrical with respect to the axis A.

[0048] The prestressing means 6 further comprise two levers 14, 26 each connecting a curved blade 55 to the same mobile body 19 arranged on the other side of the spiral spring 25 relative to the fixed support 53. The mobile body 19 is here in the form of a hook.

[0049] The variable force or torque is applied to the movable body 19. The variable force or torque is at least partly transmitted to the main flexible blades 7 of the flexible parts 15, 16 of the flexible element 5, via the levers 26.

[0050] In the embodiment of figures 1 to 4, the actuation system 20 is provided with a stud holder 31 provided with a stud 34.

[0051] The stud holder 31 is in contact with the balance bridge 22, and is held and positioned by the shock absorber 28.

[0052] During operation of the regulating member 1, the stud holder 31 is preferably fixed relative to the balance bridge 22.

[0053] The stud holder 31 comprises a central ring 38 arranged around the second bearing 28.

[0054] The stud holder 31 comprises a protrusion 41 extending radially from the central ring 38, the protrusion 41 holding the stud 34 downwards using a screw 74.

[0055] The stud 34 cooperates with the fixed support 53 of the elastic element 57. Thus, the elastic element 5 is held by the stud. The spiral spring 25 is held on the one hand by the elastic element 5, and on the other hand by the support 3.

[0056] The prestressing means 6 are also supported by the stud holder 31.

[0057] The assembly of the stud and the spiral spring 25 is for example carried out by gluing, brazing, welding, by deformation of metallic glass, or by mechanical fixing.

[0058] In order to be able to apply the variable force or torque to the spiral spring 25, the regulating member comprises an actuation system 20.

[0059] According to the invention, the actuation system 20 comprises an eccentric 10 movable in rotation cooperating with the spiral spring 25 to be able to modify its stiffness.

[0060] The eccentric 10 comprises a head 21 provided with a hollow 18 for receiving the tip of a tool for adjusting the eccentric 10. The eccentric 10 is provided with a main body 11, preferably cylindrical, extending from the head 21.

[0061] The eccentric 10 further comprises a finger 12 eccentric relative to the main axis of the main body 11 of the eccentric 10. The finger 12 extends from the main body 11. The finger 12 is mechanically linked to the prestressing means 6, but it does not block the strip 2.

[0062] The eccentric 10 is arranged through the balance bridge 22. The balance bridge 22 comprises a flared through hole 17, so as to retain the head 21 of the eccentric 10, and allow the passage of the body 11 and the finger 12 on the other side of the balance bridge 22.

[0063] The eccentric 10 is held by a flange 29 clipped around the main body 11 of the eccentric 10 under the balance bridge 22.

[0064] Preferably, the main body 11 comprises a groove 32 in which the flange 29 is inserted to retain the eccentric 10 in the hole 17.

[0065] The eccentric 10 is rotatably mounted in the balance bridge 22. Thus, it can rotate in the hole 17 and in the flange 29 around the main axis of the eccentric 10, preferably substantially perpendicular to the balance bridge 22 and/or substantially parallel to the balance shaft 24.

[0066] The finger 12 of the eccentric 10 is in contact with the movable body 19 of the prestressing means 6 in order to be able to push the levers 14, 26 more or less strongly when the eccentric 10 is turned.

[0067] Preferably, the finger 12 comprises a peripheral groove 33 cooperating with the movable body 19 of the spiral spring 25, the movable body 19 being inserted into the groove 33.

[0068] Thus, when the eccentric 10 is turned, the finger 12 presses more or less on the movable body 19, because the finger is eccentric relative to the main axis of rotation of the eccentric 10.

[0069] The movement of the finger 12 against the movable body modifies the stiffness of the elastic element 5, because the movement exerts a more or less significant force or torque on the movable body 19 of the prestressing means 6, so that the stiffness of the flexible parts 15, 16 of the elastic element 5 varies, by means of the levers 26, and thus the stiffness of the entire spiral spring 25. The actuation system 20 thus makes it possible to adjust the operation of the regulating member 1.

[0070] To this end, the actuation system 20 makes it possible to modify the position of the finger 12.

[0071] The actuation system 20 is configured to adjust the rate of the regulating member 1 with a resolution less than or equal to 1 second per day, preferably less than or equal to 0.5 seconds per day, or even less than or equal to 0.1 seconds per day. The configuration of the regulating member 1 makes it possible to achieve such precision.

[0072] Naturally, the invention is not limited to the embodiment of the regulating member described with reference to the figures, and variants could be envisaged without departing from the scope of the invention.

Claims (13)

1. Regulating member (1) for a watch movement comprising an inertial mass, for example a balance (23), a balance spring (25), a balance bridge (22) and an actuating system (20) for adjusting the rate of the balance spring (25), the balance spring (25) comprising a wound ribbon (2) and means (30) for adjusting the stiffness of the balance spring provided with an elastic element (5) arranged in series with the wound ribbon (2), the adjustment means (30) comprising pre-stressing means (6) for applying a variable force or torque to the flexible element (5), characterized in that the actuating system (20) comprises an eccentric (10) actuating the pre-stressing means (6) of the adjustment means (30). 2. Regulating organ according to claim 1, characterized in that the eccentric (10) is rotatably mounted through the balance bridge (22). 3. Regulating member according to claim 1 or 2, characterized in that the eccentric (10) comprises a head (21) and a main body (11) extending from the head (21). 4. Regulating member according to claim 3, characterized in that the eccentric (10) comprises a finger (12) extending from the main body (11), the finger (12) being eccentric relative to the main axis of the main body (11) of the eccentric (10). 5. Regulating member according to claim 3 or 4, characterized in that the head (21) comprises a hollow (18) intended to receive the tip of a tool making it possible to actuate the eccentric (10). 6. Regulating member according to any one of the preceding claims, characterized in that the prestressing means (6) comprise a first movable lever (14) connected to the flexible element (5), the eccentric (10) being in direct or indirect contact with the lever (14) in order to be able to actuate it. 7. Regulating member according to claim 6, characterized in that the prestressing means (6) comprise a second movable lever connected to the flexible element (5), the eccentric (10) being in direct or indirect contact with the second lever (26) in order to be able to actuate it. 8. Regulating member according to claim 6 or 7, characterized in that the prestressing means (6) comprise a movable body (19) connected to the first lever (14) and/or the second lever (26), the finger (12) being in contact with the movable body (19). 9. Regulating member according to claim 8, characterized in that the finger (12) comprises a peripheral groove (33) cooperating with the movable body (19). 10. Regulating member according to any one of the preceding claims, characterized in that the actuation system (20) comprises a stud holder (31) comprising a stud (34) on which the spiral spring (25) is mounted, the stud (34) being mechanically linked to the elastic element (5) of the spiral spring (25). 11. Regulating member according to any one of the preceding claims, characterized in that the stud holder (31) is arranged on the balance bridge (22) around a bearing (28) of the balance shaft (24). 12. Clock movement, characterized in that it comprises a regulating organ (1) according to any one of the preceding claims. 13. Timepiece, for example a watch, characterized in that it comprises a timepiece movement according to claim 12.