Timepiece adjustment member including improved index system, timepiece movement and timepiece

Abstract

To provide an adjust member for a timepiece movement which is adjustable with extremely high accuracy.SOLUTION: An adjustment member 1 for a timepiece movement includes an index system for adjusting an inertia mass, for example, a balance 23, a balance-spring 25, a balance bridge 22, and a speed of the balance-spring 25, wherein the index system includes a stud holder including a first stud 34 on which the balance-spring 25 is mounted, the balance bridge 22 includes a second stud 35 on which the balance-spring 25 is mounted again, and the stud holder is rotatable to the balance bridge 22 so as to adjust a speed of the adjustment member 1.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to the field of watchmaking, and in particular to the field of mechanical watchmaking, in which the regulation of the drive energy is provided by an adjustment member. In particular, the present invention relates to an adjustment member provided with a precision index system, to a clock movement including such an adjustment member, and to a clock including such a clock movement. [Background technology]

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

[0003] The inner end of the balance spring is attached to a staff that rotates with the balance, and the outer end of the balance spring is attached to a stud mounted in a stud holder that is itself rigidly connected to the fixed bridge.

[0004] The balance is kept rotating and its oscillations are counted by an escapement mechanism, which consists of a pallet lever moving with a low amplitude oscillatory motion, provided with two pallets which mesh with the teeth of the escape wheel. When the escape wheel thus meshes, it rotates in steps, the frequency of whose rotations is determined by the frequency of oscillation of the pallet lever, which is itself set to the frequency of oscillation of the balance spring.

[0005] In a conventional escapement, the oscillation frequency is approximately 4Hz, or approximately 28,800 vibrations per hour (V / h). One of the aims of a good watchmaker is to ensure the isochronism and regularity (or constancy of rate) of the oscillations of the balance.

[0006] The speed of the balance can be adjusted in a known manner by adjusting the effective length of the balance spring, defined as the curvilinear length between the inner end of the balance spring and a counting point located near the outer end of the balance spring, typically defined by a pair of bankings carried by a key mounted on an indexing system.

[0007] In operation, this indexing system cannot rotate about the axis of the balance spring, but its angular position can be adjusted by manual intervention, for example using a screwdriver to pivot an eccentric that acts like a cam in the indexing system.

[0008] The assembly including the bridge, index system, keys, stud holders, studs, staff, hairspring and balance is commonly referred to as the "adjusting member". Examples of adjusting members are given in US Pat. No. 5,399,433 and US Pat. No. 5,499,443, both filed by the watch manufacturer ETA.

[0009] There are indexing systems that have a stud holder to which the outer end of the balance spring is attached, where the keys of the indexing system leave some play that allows the balance spring to move between the two bankings. However, chronometric properties, especially anisochronism, are very sensitive to play in the indexing keys, and this play is difficult to control precisely.

[0010] In some devices, these bankings can be adjusted to clamp the balance spring to eliminate play, especially when the balance spring is running. In this case, the speed is adjusted first by moving the index key, and then the balance spring is clamped to the key. However, clamping the balance spring to the index key runs the risk of stressing the balance spring and of introducing errors in the chronometer, especially due to a shift in the centre of winding. Moreover, since eliminating play also changes the speed, once the balance spring has been clamped, it is no longer possible to move the index key along the balance spring to complete the fine adjustment of the speed.

[0011] Other hairsprings also have an integrated adjustment device. In these hairsprings, the speed is adjusted not by modifying the effective length of the hairspring, but by exerting a force or torque on a flexible element arranged in series with the hairspring. In this way, the stiffness of the flexible element and thus the stiffness of the entire hairspring can be modified. Adjusting the stiffness of the hairspring allows adjusting the speed of the adjustment member. Such hairsprings provided with flexible elements are described, for example, in US Pat. No. 5,399,323.

[0012] However, in these cases, the usual indexing system cannot be used, since it is not compatible with the balance spring adjustment device. Moreover, since the speed needs to be adjusted with great precision, it is essential that there is no play between the balance spring and the area where it interacts with the indexing mechanism. In particular, if this is not the case, in the event of an impact, there is a risk that the speed will be altered if the balance spring does not return to exactly the same position itself after said impact. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] European Patent Application Publication No. 3304215 [Patent Document 2] European Patent Application Publication No. 2876504 [Patent Document 3] European Patent Application Publication No. 4009115 Summary of the Invention

[0014] SUMMARY OF THE PRESENT EMBODIMENT It is an object of the present invention to overcome some or all of the above mentioned drawbacks by providing an indexing system adapted for adjustment devices of this type.

[0015] To this end, the invention relates to an adjustment member for a timepiece movement, comprising an inertial mass, for example a balance, a hairspring, a balance bridge and an indexing system for adjusting the speed of the adjustment member, the indexing system comprising a stud holder comprising a first stud on which the hairspring is mounted.

[0016] The invention is characterized in that the balance bridge includes a second stud, on which the balance spring is also mounted, the stud holder being rotatable relative to the balance bridge to adjust the speed of the adjustment member.

[0017] With the present invention, the speed of the adjustment member can be adjusted simply by changing the position of the stud holder, since this changes the position of the first stud relative to the second stud, which remains stationary relative to the plate. Since the balance spring is carried by two studs, the stiffness of the balance spring is modified. Since the position of the second stud does not change, the guide marks also remain unchanged.

[0018] In certain embodiments of the invention, the indexing system includes a return spring that exerts an expansion force between the stud holder and the balance bridge.

[0019] In certain embodiments of the invention, the stud holder and the spring are integral and preferably made from the same material.

[0020] In certain embodiments of the invention, the indexing system includes a rotatable cam that cooperates with the stud holder to rotate the stud holder.

[0021] In certain embodiments of the invention, the stud holder includes an arm that contacts the cam to allow the stud holder to rotate.

[0022] In a particular embodiment of the invention, the hairspring comprises a wound ribbon and a means for adjusting the stiffness of the hairspring, the means being provided with a flexible element arranged in series with the wound ribbon, the second stud being mechanically connected to the flexible element.

[0023] In a particular embodiment of the invention, the flexible element is connected to a rigid support and the second stud is integrated into the rigid support.

[0024] In a particular embodiment of the invention, the adjustment means comprises compressive stress means for exerting a variable force or torque on the flexible element, the first stud being mechanically connected to the compressive stress means.

[0025] In a particular embodiment of the invention, the flexible element and the compressive stress means are arranged between a first stud and a second stud, the first stud being movable relative to the second stud to activate the compressive stress means, and displacement of the first stud relative to the second stud modifies the stiffness of the balance spring.

[0026] In a particular embodiment of the invention, the compressive stress means comprises a lever connected to the flexible element, the first stud being integrated into the free end of the lever.

[0027] In a particular embodiment of the invention, the compressive stress means comprises a rigid structure arranged parallel to the flexible element, the lever being connected to the rigid structure.

[0028] In a particular embodiment of the invention, the flexible element is connected to a rigid support and the second stud is integrated into the rigid support.

[0029] In a particular embodiment of the invention, the stud holders are arranged in a balance bridge around bearings in the balance staff.

[0030] The invention further relates to a clock movement including such an adjustment member.

[0031] The invention further relates to a timepiece, such as a wristwatch, comprising such a timepiece movement. [Brief description of the drawings]

[0032] The objects, advantages and features of the present invention will become apparent after reading some embodiments given with reference to the attached drawings, which are given for illustrative purposes only and are not intended to limit the scope of the invention.

[0033] [Figure 1] FIG. 2 shows a schematic perspective top view of an adjustment member according to a first embodiment of the present invention; [Diagram 2] 2 shows a schematic perspective top partial exploded view of a first embodiment of the adjustment member in FIG. 1; [Diagram 3] FIG. 2 shows a schematic top view of the balance spring of the adjustment member according to the invention; [Figure 4] 2 shows a schematic perspective bottom partial exploded view of the first embodiment of the adjustment member shown in FIG. 1; [Diagram 5] FIG. 2 shows a schematic bottom view of the first embodiment of the adjustment member shown in FIG. 1; [Figure 6] 5A and 5B show schematic perspective partial top views of an adjustment member according to a second embodiment of the present invention; [Figure 7] 7 shows a schematic enlarged fragmentary view of a portion of the second embodiment of the adjustment member shown in FIG. 6; [Figure 8] 7 shows a schematic perspective top view of a stud holder of the second embodiment of the adjustment member shown in FIG. 6; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] 1 to 5 show diagrammatically a first embodiment of an adjustment member 1 intended to be arranged in a clock movement not shown in the drawings, such a clock movement comprising, for example, a plate provided with a recess for receiving the adjustment member 1 with an inertial mass and an elastic return element arranged to oscillate the inertial mass.

[0035] The adjustment member 1 further comprises an indexing system 20, an annular balance 23 as an inertial mass, a balance staff 24, a hairspring 25 as an elastic return element, and a balance bridge 22.

[0036] 1 to 3, the balance 23, the hairspring 25, the balance bridge 22 and the index system 20 are stacked from bottom to top in this example.

[0037] The balance staff 24 is centrally arranged and passes through the centre of the balance 23, the hairspring 25 and the balance bridge 22. The balance staff 24 is held by two shock-resistant bearings 28 arranged at both ends of the balance staff 24. A first bearing, not shown in the drawings, is arranged below the balance 23 and the balance bridge 22, and a second bearing 28 is held by the balance bridge 22. The balance bridge 22 is provided with a hole, in this case a through hole, in which the second bearing 28 is held. The indexing system 20 is mounted on the balance bridge 22 and, in this embodiment, arranged along the central axis of the balance staff 24.

[0038] 3 shows an example of a hairspring 25, which preferably extends substantially in one plane. The hairspring 25 comprises a flexible ribbon 2 wound around itself with several turns, this ribbon 2 having a predefined stiffness. An inner end 9 of the ribbon 2 is integrated into or assembled with a support 3, typically called a collet. The support 3 is substantially triangular in shape and is screwed around the staff of the balance 24.

[0039] The hairspring 25 further includes means for adjusting its stiffness, for example, the adjustment means being specifically actuated by an operator once the adjustment member is mounted on a plate of the timepiece movement.

[0040] The adjustment means comprises flexible elements 5 arranged in series on the ribbon 2, the flexible elements 5 connecting one end 4 of said ribbon 2 to a rigid support 17 and integrated into one of the ends 4 of the ribbon 2. The flexible elements 5 are integrated into the outer end 4 of the ribbon 2. The flexible elements 5 are distinct elements from the ribbon 2.

[0041] The flexible element 5 adds additional stiffness to that of the ribbon 2. The flexible element 5 is preferably stiffer than the ribbon 2. In this case, the flexible element 5 is arranged as an extension of the ribbon 2. Preferably, the adjustment means and the ribbon 2 are integral or may be made from the same material, e.g. silicone.

[0042] The flexible element 5 of the hairspring 25 comprises a pivot with non-intersecting flexible blades. The pivot comprises two non-intersecting flexible blades 11, 12 and a rigid part 18. The flexible blades 11, 12 are laterally joined on the one hand to a rigid support 17 and on the other hand to the rigid part 18, moving towards each other. That is to say, the flexible blades 11, 12 preferably extend away 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 immobile with respect to the plate. The rigid support 17 is L-shaped, with a first leg 46 of the L acting as a connection with the flexible blades 11, 12 and a second leg 47 of the L facing away from the pivot with non-intersecting blades so that it can be assembled into a clock movement.

[0043] The means for adjusting the hairspring 25 further comprise compressive stress means 6 which exert a variable force or torque on the flexible element 5. In this way the stiffness of the hairspring can be adjusted. The torque or force is continuously adjustable thanks to the compressive stress means 6; in other words the torque or force is not limited to discrete values. The stiffness of the flexible element 5 can thus be adjusted very precisely.

[0044] The compressive stress means 6 includes a secondary flexible blade 19 arranged on the opposite side of the rigid portion 18 in the extension of the pivot with non-intersecting blades. The secondary flexible blade 19 is arranged in a tangential direction towards the ribbon 2 at the outer end 4.

[0045] The other end of the secondary flexible blade 19 is connected to a curved lever 14 that extends around the ribbon 2. In addition to the secondary flexible blade 19, the lever 14 is also connected to a rigid structure 27 that is attached to the rigid support 17. The rigid structure 27 has a portion that deforms when the lever 14 is actuated by a force or torque.

[0046] This force or torque is exerted on the free end 15 of the lever 14. In this way, the lever 14 of the compression stress means 6 transmits the force or torque to the flexible element 5 via the secondary flexible blade 19 and the rigid structure 27 in order to modify the stiffness of the balance spring 25.

[0047] 1 and 2, the balance spring 25 has a different configuration: the non-intersecting blades 11, 12, the rigid part 18 and the secondary flexible blade 19 are replaced by a single blade, and the outer end 4 of the lever 14 is attached to the single blade.

[0048] In order to be able to exert a variable force or torque on the balance spring 25 , the adjustment member includes an indexing system 20 .

[0049] In the first embodiment shown in figures 1, 2, 4 and 5, the indexing system 20 is mounted on a stud holder 31 provided with a first stud 34.

[0050] According to the invention, the balance bridge 22 is provided with a second stud 35. The stud holder 31 is mechanically connected to the lever 14 of the compressive stress means 6 but does not block the ribbon 2.

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

[0052] The stud holder 31 can rotate about the balance staff relative to the balance bridge 22 so as to move the first stud 34 and act on the lever 14 .

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

[0054] The stud holder 31 includes two projections 41, 42 extending radially from a central ring 38. The first projection 41 presses down the first stud 34 by a first screw 74. The second projection 42 presses down the second stud 35 by a second screw.

[0055] In the reference arrangement, the first stud 34 and the second stud 35 are arranged substantially symmetrically with respect to the staff of the balance 24, for example.

[0056] The first stud 34 cooperates with the free end 15 of the lever 14 and the second stud 35 cooperates with a second leg 47 of the rigid support 17. Thus, the compressive stress means 6 is supported by the indexing system 20 and the flexible element 5 is supported by and suspended from the balance bridge 22.

[0057] Two studs 34, 35 are arranged on either side of the compressive stress means 6 and the flexible element 5. Furthermore, these two studs 34, 35 are rigidly connected to the lever 14 and to the rigid support 17. In other words, the first stud 34 and the second stud 35 are respectively integrated by their free ends 15 to the lever 14 and by their second legs 47 to the rigid support 17. These studs and the balance spring 25 are assembled, for example, by gluing, brazing, welding, deformation of metallic glass or mechanical fastening.

[0058] The first stud 34 is movable relative to the second stud 35. To this end, the stud holder 31 is made movable relative to the balance bridge 22. The stud holder 31 can rotate about the second bearing 28, i.e. the first stud 34 moves together with the stud holder 31 and the first stud 34 is rotatable about the second bearing 28. The first stud 34 can be displaced over an angular range of, for example, 20° or more appropriately, 10°.

[0059] The displacement of the first stud 34 relative to the second stud 35 modifies the stiffness of the flexible element 5, since this displacement exerts a greater or lesser force or torque on the lever 14 of the compressive stress means 6. As a result, the stiffness of the flexible element 5 and thus the overall stiffness of the balance spring 25 also changes. The indexing system 20 thus allows the speed of the adjusting member 1 to be adjusted.

[0060] To this end, the indexing system 20 allows the position of the first stud 34 to change relative to the second stud 35. Movement of the stud holder 31 relative to the balance bridge 22 results in movement of the first stud 34 relative to the second stud 35, modifying the force or torque exerted on the compression stress means 6 of the balance spring 25.

[0061] The stud holder 31 of the indexing system 20 includes an arm 63 that extends radially outward in one plane.

[0062] The indexing system 20 includes a rotatable cam 55 arranged on the balance bridge 22. The cam 55 cooperates with an arm 63 of the stud holder 31 to rotate the arm 63 about the second bearing 28. One end 56 of the arm 63 is preferably in permanent contact with the cam 55, so that the rotation of the cam 55 exerts a constant movement on the arm 63 depending on the angular position of the cam 55. That is, the stud holder 31 of the indexing system 20 rotates about the second bearing 28. Such an indexing system 20 equipped with a cam 55 allows the stiffness of the balance spring 25 to vary linearly.

[0063] To keep the arm 63 of the stud holder 31 in contact with the cam 55 , the indexing system 20 includes a spring 57 which exerts a return force on the stud holder 31 .

[0064] 4, the spring 57 is substantially horseshoe shaped with a first end 58 of the spring connected to the balance bridge 22 and a second end 59 of the spring 57 surrounding a retaining stud 60 extending from the stud holder 31. The spring 57 is arranged on the side of the balance 23 and hairspring 25 in a hollow 61 made in the balance bridge 22. The balance bridge 22 includes a through hole 62 that opens into the hollow 61, and the retaining stud 60 extends through the through hole 62 into the hollow 61. The through hole 62 is dimensioned to allow the retaining stud 60 to move as the stud holder 31 rotates relative to the balance bridge 22.

[0065] That is, the spring 57 exerts a return force on the stud holder 31 of the indexing system 20 which serves to permanently maintain the arm 63 of the stud holder in contact with the cam 55. As the cam 55 acts, the stud holder 31 rotates to move the first stud 34 relative to the second stud 35, whilst being subjected to the return force exerted by the spring 57, in particular allowing the arm 63 of the stud holder 31 to contact the cam 55 even when the peripheral wall 64 of the cam 55 moves away from the arm 63.

[0066] The indexing system 20 is configured to adjust the speed of the adjustment member 1 with a resolution of 1 second per day or less, preferably 0.5 seconds per day or less, and more preferably 0.1 seconds per day or less. The configuration of the adjustment member 1 allows such precision to be achieved.

[0067] The adjustment marks 49 are also aligned on the cam 55. Thus, to adjust the indexing system 20, the cam 55 is moved, for example, by a rotatable adjustment knob (not shown in the drawings) aligned on the cam 55. That is, the cam 55 is oriented according to the preferred guide marks to adjust the indexing system 20.

[0068] Preferably, the adjustment marks 49 correspond to this resolution. In other words, the difference between two consecutive guide marks allows the speed to change by 1 second, 0.5 seconds, or even 0.1 seconds per day. In Fig. 6, the resolution of the adjustment marks 49 is 0.1 seconds.

[0069] Figures 6 to 8 show diagrammatically a second embodiment of an adjustment member 40 according to the invention. In this embodiment, the stud holder 71 and the spring 72 are integral and preferably made from the same material. In all other respects the adjustment member 40 is the same as the first embodiment.

[0070] The stud holder 71 includes a single protrusion 81 which carries the first stud 34. The stud holder 71 includes a spring 72 in place of a second protrusion.

[0071] The spring 72 is elongated and extends from the ring 737 of the stud holder 71 to the opposite side of the arm 81. The spring 72 is U-shaped and rests against the balance bridge 52 when the stud holder 71 is mounted on the adjustment member 40. A first end 75 of the U is integrated into the ring 77 of the stud holder 71, while a second end 76 is free.

[0072] The second end 76 is inserted into a hole in the balance bridge 52. The free second end 76 includes, for example, a bent portion 79 that is hooked into the hole, i.e. the second end 76 of the spring 72 is supported in the hole to lock the spring 72 on this side.

[0073] That is, as the stud holder 71 rotates, under the influence of the movement of the cam 55 the spring 72 is subjected to a greater or lesser stress and exerts a return force on the stud holder 71 to hold the arm 63 against the cam 55 whatever its position.

[0074] Alternatively, the free second end 76 may be wedged to an edge 78 of the balance bridge 52 .

[0075] Apart from these differences, the adjustment member 40 of the second embodiment has the same characteristics as the adjustment member of the first embodiment, in particular with respect to the cam 55, the first stud 34 and the second stud 35 and the balance spring 25.

[0076] Such a stud holder 71 makes it easier to fit the stud holder 71 into the adjustment member, since only one component is arranged on the balance bridge. Storage is also simplified, since two components are replaced by a single component.

[0077] It goes without saying that the invention is not limited to the embodiment of the adjustment member described with reference to the drawings, but alternatives are possible without departing from the scope of the invention.

Claims

1. A regulating member (1, 40) for a timepiece movement comprising an inertial mass, e.g. a balance (23), a hairspring (25), a balance bridge (22) and an indexing system (20) for adjusting the speed of said hairspring (25), said indexing system (20) comprising a stud holder (31, 71) comprising a first stud (34) on which said hairspring (25) is mounted, characterized in that said balance bridge (33, 53) comprises a second stud on which said hairspring (25) is also mounted, said stud holder (31, 71) being rotatable relative to said balance bridge (22, 52) for adjusting the speed of said regulating member (1, 40).

2. 2. An adjustment member according to claim 1, characterized in that the balance spring (25) comprises a wound ribbon (2) and means for adjusting the stiffness of the balance spring, said means being provided with a flexible element (5) arranged in series with the wound ribbon (2), said second stud (35) being mechanically connected to said flexible element (5).

3. 3. An adjustment member according to claim 2, characterized in that the adjustment means comprises compressive stress means (6) for exerting a variable force or torque on the flexible element (5), and the first stud (34) is mechanically connected to the compressive stress means (6).

4. 4. An adjusting member according to claim 3, characterized in that the flexible element (5) and the compression means (6) are arranged between the first stud (34) and the second stud (35), the first stud (34) being movable relative to the second stud (35) to activate the compression means (6), and the displacement of the first stud (34) relative to the second stud (35) modifies the stiffness of the balance spring (25).

5. 5. An adjustment member according to claim 4, characterized in that said compressive stress means (6) comprise a lever (14) connected to said flexible element (5) and said first stud is integrated into a free end (15) of said lever (14).

6. 4. An adjustment member according to claim 3, characterized in that said compressive stress means (6) comprise a rigid structure arranged parallel to said flexible element (5), said lever (14) being connected to said rigid structure.

7. 3. An adjustment member according to claim 2, characterized in that said flexible element (5) is connected to a rigid support (17) and said second stud (35) is integrated in said rigid support (17).

8. 2. An adjustment member according to claim 1, characterized in that the indexing system (20, 60) comprises a rotatable cam (55) which cooperates with the stud holder (31, 71) to rotate the stud holder (31, 71).

9. 9. An adjustment member according to claim 8, characterized in that the stud holder (31, 71) comprises an arm (63) which contacts the cam so as to allow the stud holder to rotate.

10. 2. An adjustment member according to claim 1, characterized in that the indexing system (20, 60) comprises a return spring (57, 72) exerting an expansion force between the stud holder (31, 71) and the balance bridge (22, 52).

11. 11. Adjustment member according to claim 10, characterized in that the stud holder (31, 71) and the spring (57, 72) are integral and preferably made from the same material.

12. 2. An adjustment member according to claim 1, characterized in that the stud holder (31, 71) is arranged on the balance bridge (22, 52) around a bearing (28) on the balance staff (24).

13. A clock movement, characterized in that it includes an adjustment member (1, 40) according to claim 1.

14. A timepiece, such as a wristwatch, characterized in that it includes a timepiece movement according to claim 13.

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