Spiral hairspring for a timepiece resonator mechanism provided with a device for adjusting the effective length of the spiral hairspring

Abstract

The invention relates to a spiral balance spring (1) for a timepiece resonator mechanism, the spiral balance spring (1) extending substantially in a plane and comprising a flexible blade (2) wound on itself with a number of turns and an adjustment device for varying the effective length of the wound blade (2), the adjustment device comprising a clamp (3) displaceable along at least one end portion (6) of the spiral balance spring (1), the clamp (3) extending substantially in the plane of the spiral balance spring (1), the clamp (3) comprising two bearing surfaces (4, 5) arranged in a variety of positions on either side of the wound blade (2) so as to define a variable effective length of the spiral balance spring (1), the clamp (3) and the wound blade (2) being connected to each other by a flexible element (7) so as to allow the clamp (3) and the bearing surfaces (4, 5) to be displaced along the wound blade (2).

Description

Technical Field

[0001] The invention relates to a spiral balance spring for a timepiece resonator mechanism, the spiral balance spring being provided with a device for adjusting the effective length of the spiral balance spring. The invention also relates to a timepiece resonator mechanism provided with such a spiral balance spring. Background Art

[0002] The quest to improve the performance of watchmaking time bases is a constant concern. The main limitation in the chronometric performance of mechanical watches is the use of conventional impulse escapements.

[0003] The balance spiral hairspring should usually be able to be adjusted in order to improve the precision of the watch. For this purpose, devices for adjusting the stiffness of the spiral hairspring are used, such as indexing pieces for adjusting the effective length of the spiral. Thus, its stiffness is varied in order to adjust the running time of the watch. However, the effect of conventional indexing pieces in adjusting the running time is still limited, and it is not always effective in making the adjustment sufficiently precise, in the order of a few seconds or tens of seconds per day.

[0004] In order to improve the precision of adjustment, document CH286562 describes a spiral hairspring provided with a clamp capable of clamping the end of the spiral hairspring in a plurality of positions, thereby varying the effective length of the spiral hairspring and thus allowing the balance wheel to be adjusted. In addition, one or more rollers forming the clamp can be rotated to select the length of the spiral hairspring.

[0005] However, in order to change the position of the clamp, it is necessary to act on the part by displacing it and tightening it with a screw. This mode of adjustment is not easy to perform and does not allow obtaining a sufficient fine adjustment of the oscillator's timing. Summary of the invention

[0006] The object of the present invention is to overcome all or part of the above-mentioned drawbacks by proposing a spiral balance spring provided with effective and precise adjustment means, which are configured in particular to adjust the performance of a timepiece by varying the effective length of said spiral.

[0007] To this end, the invention relates to a spiral balance spring for a timepiece resonator mechanism, the spiral balance spring extending substantially in a plane and comprising a flexible blade wound on itself with several turns and an adjustment device for varying the effective length of the wound blade, the adjustment device comprising a clamp displaceable along at least one end portion of the spiral balance spring, the clamp extending substantially in the plane of the spiral balance spring, the clamp comprising two bearing surfaces arranged in a variety of positions on either side of the wound blade so as to define a variable effective length of the spiral balance spring.

[0008] The invention is characterized in that the clamp and the wound blade are connected to each other by a flexible element, thereby allowing a fine displacement of the clamp and the support surface along the wound blade.

[0009] An effective adjustment device is thus obtained, which allows the effective length of the spiral balance spring to be adjusted in a controlled manner. Thus, the rate of the timepiece can be adjusted easily and accurately.

[0010] According to a particular embodiment of the invention, the two bearing surfaces are configured to bear against the wound blades.

[0011] According to a particular embodiment of the invention, the two bearing surfaces are configured to be at a distance from the winding vane which contacts the bearing surfaces during operation of the spiral balance spring.

[0012] According to a particular embodiment of the invention, the clamp and the wrapped blade are made in a single piece, preferably made of silicon.

[0013] According to a particular embodiment of the invention, the wound blade comprises a tip portion, the bearing surface of the clamp being configured to be displaced on both sides of the tip portion.

[0014] According to a particular embodiment of the invention, the end portion comprises a variable width in order to vary its stiffness and therefore the sensitivity of the travel time regulation.

[0015] According to a particular embodiment of the invention, the clamp comprises two branches extending on either side of the end of the spiral balance spring, the end of each branch comprising one of said bearing surfaces.

[0016] According to a particular embodiment of the invention, the flexible element comprises at least two flexible leaves connected on the one hand to the branches and on the other hand to the terminal portions of the intertwined leaves.

[0017] According to a particular embodiment of the invention, in the rest position of the flexible element, the flexible blade is substantially perpendicular to the end portion.

[0018] According to a particular embodiment of the invention, the flexible blade partially surrounds the tip portion.

[0019] According to a particular embodiment of the invention, the clamp comprises a rigid member and two movable bodies, each movable body comprising one of said bearing surfaces.

[0020] According to a particular embodiment of the invention, the flexible element comprises at least two flexible blades to connect each movable body to the rigid member.

[0021] According to a particular embodiment of the invention, the flexible element comprises a translation platform connected on the one hand to the clamp and on the other hand to the end portion.

[0022] According to a particular embodiment of the invention, the translation platform comprises at least one second flexible blade, preferably two flexible blades, and a rigid part, one or more second flexible blades being coupled to the rigid part and the rigid member, the end portion of the wound blade being coupled to the rigid part.

[0023] According to a particular embodiment of the invention, the flexible element comprises two springs, each spring being connected on the one hand to the rigid part of the translation platform and on the other hand to each movable body.

[0024] Furthermore, the invention relates to a timepiece resonator comprising a balance wheel, characterised in that it comprises a spiral balance spring according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Other features and advantages will clearly emerge from the following description, given by way of indication and in no way limiting, with reference to the accompanying drawings, in which:

[0026] Figure 1 is a schematic diagram of a spiral hairspring provided with an adjustment device according to a first embodiment of the present invention;

[0027] Figure 2 is a schematic diagram of a spiral hairspring provided with an adjustment device according to a second embodiment of the present invention;

[0028] Figure 3 is a schematic diagram of a spiral hairspring provided with an adjustment device according to a third embodiment of the present invention;

[0029] Figure 4 is a schematic diagram of an adjusting device for a spiral hairspring according to a fourth embodiment of the present invention;

[0030] Figure 5 Schematic diagram of an adjusting device for a spiral hairspring according to a fifth embodiment of the present invention. DETAILED DESCRIPTION

[0031] exist Figures 1 to 5 In the invention, the invention relates to different embodiments of a spiral balance spring 1, 10, 20, 30, 40 for a timepiece resonator mechanism. The resonator mechanism comprises a balance wheel, generally circular, the oscillation frequency of which is determined in particular by the spiral balance spring 1, 10, 20, 30, 40. The spiral balance spring 1, 10, 20, 30, 40 extends substantially in a plane and comprises a flexible winding blade 2 wound on itself with several turns, which preferably extends in the same plane. The winding blade 2 of the spiral balance spring 1, 10, 20, 30, 40 comprises an end portion 6 which is preferably substantially straight. In Figures 1 to 3In the embodiment of the present invention, the end portion 6 comprises a rigid portion 15 forming the end of the end portion 6 and a thin portion 16 preceding the rigid portion 15. Preferably, the rigid portion 15 is fixed to the movement to prevent the end portion 6 from shifting. The thin portion 16 is at least partially embedded in the thick rigid portion 15. Figure 4 and Figure 5 In the embodiment of the invention, the end portion 6 does not comprise a rigid portion.

[0032] In order to vary the oscillation frequency of the resonator, the spiral balance spring 1, 10, 20, 30, 40 comprises an adjustment device allowing the effective length of said spiral balance spring 1 to be varied. Thus, the length of the balance spring can be adapted to regulate the timing of the resonator as well as possible. The adjustment device comprises a clamp 3, 33, 53, 63 which can be displaced along at least a portion of the spiral. Preferably, the clamp 3, 33, 53, 63 extends substantially in the same plane as the spiral balance spring 1, 10, 20, 30, 40. Preferably, the clamp 3, 33, 53, 63 and the wound blade 2 are made in one piece. In other words, they are made of the same material, for example silicon.

[0033] The clamp 3, 33, 53, 63 comprises two bearing surfaces 4, 5, 24, 25, 48, 49, 66, 67 which are configured to bear on both sides of the wound blade 2 in a variety of positions depending on the adjustment. Thus, the clamp 3, 33, 53, 63 allows to define a variable effective length of the spiral balance spring 1, 10, 20, 30, 40 depending on its position on the flexible wound blade. The bearing surfaces 4, 5, 24, 25, 48, 49, 66, 67 are in contact with the end portion 6 of the wound blade 2, for example, and can be displaced along this end portion 6, in particular along the thin portion 16.

[0034] According to the present invention, the clamp 3, 33, 53, 63 and the wound blade 2 are assembled to each other by means of the flexible element 7, 17, 51, 87. The flexible element 7, 17, 51, 87 is configured to be pressed so as to allow the bearing surface 4, 5, 24, 25, 48, 49, 66, 67 to be displaced along the end portion 6 of the wound blade 2. The pressing is performed in a direction substantially parallel to or even colinear with the end portion 6 of the wound blade 2. By applying a force to the flexible element 7, 17, 51, 87, the clamp 3, 33, 53, 63 is displaced and changes its position on the end portion 6. In addition, by adapting the size of the clamp, the strength of the pressing force can be adjusted.

[0035] The clamp 3, 33, 53, 63 and the wound blade 2 are connected in two ways. The first connection is a fixed connection, the wound blade and the clamp are each assembled to the flexible element 7, 17, 51, 87. The second connection is a movable connection formed between the support surface 4, 5 and the wound blade 2. This movable connection can be displaced along the end portion 6 to select the effective length of the wound blade. The fixed connection is therefore a different connection from the support surface and the wound blade that form the movable connection.

[0036] In order to be able to exert pressure on the clamps 3,33,53,63, an application device not shown in the figure is used. The application device is for example a lever, a screw oriented longitudinally of the clamp or an eccentric screw whose head is placed against the clamp 3,33,53,63.

[0037] exist Figure 1 In the first embodiment of the present invention, the clamp 3 comprises two branches 8, 9 extending on both sides of the winding blade 2 of the spiral balance spring 1. The branches 8, 9 are preferably flexible, and one end of each branch 8, 9 comprises one of the bearing surfaces 4, 5. The branches 8, 9 have the shape of an arc of a circle ending with a curved bearing surface 4, 5. The branches 8, 9 are configured so that the two bearing surfaces 4, 5 are in contact on both sides of the winding blade 2. Therefore, the end portion 6 of the winding blade passes between the two bearing surfaces 4, 5.

[0038] The clamp 3 comprises at least two flexible blades 11, 12 connected on the one hand to the branches 8, 9 and on the other hand to the terminal portion 8 of the wound blade 2. The flexible blades 11, 12 allow the branches 8, 9 to be displaced relative to the terminal portion 6 of the wound blade 2. The flexible blades 11, 12 are arranged on both sides of the terminal portion 6. The flexible blades 11, 12 are curved so that they can extend or contract when the clamp 3 is displaced along the terminal portion 6. The curvature of the flexible blades 11, 12 is directed towards the branches 8, 9 and is arranged in the plane of the spiral balance spring 1. Therefore, the flexible blades 11, 12 partially surround the terminal portion 2.

[0039] Depending on the position of the clamp 3, the bearing surfaces 4,5 meet in different positions of the thin portion 16. The flexible blades 11,12 are assembled on the one hand to the free end 13 of the terminal portion 6, in particular the rigid portion, and on the other hand to the ends of the branches 8,9, that is to say at the bearing surfaces 4,5.

[0040] Thus, when the clamp 3 is pushed, the flexible element 7 extends, and when the pressure is withdrawn, the flexible element 7 retracts into its initial state. Figure 1 In the embodiment of the present invention, the curvature of the flexible blades 11, 12 is increased or decreased.

[0041] The clamp 3 comprises a longitudinal rigid member 14, which is arranged substantially perpendicular to the end portion 6 and to which a force is applied by the above-mentioned application means. The branches 8, 9 are connected to the ends of the rigid member 14. Therefore, when the rigid member 14 is pressed by the application means, the branches 8, 9 move forward or backward, so that the contact surfaces 4, 5 are displaced along the end portion 8. The member 14 is arranged at a distance from the rigid portion 15 to allow the member 14 to move closer to and away from the rigid portion 15 when the flexible element 7 is pressed.

[0042] exist Figure 2 In the second embodiment of the spiral balance spring 10, the clamp 23 comprises branches 18, 19 of an inverted L shape, and the branches 18, 19 are preferably rigid. The branches 18, 19 are connected to each end of the rigid member 14 by rigid rods 29, 31 in the shape of an arc, each rod 22 starting from the corner of the L. The bend of the arc of the rod points to the outside of the clamp 23. The rigid member 14 is substantially perpendicular to the end portion 6 of the wound blade 2. Each L-shaped branch 18, 19 comprises a substantially vertical large section 33, 34 and a small section 27, 28. The ends of the small sections 27, 28 of the L form two bearing surfaces 24, 25 between which the end portion 6 of the wound blade 2 passes.

[0043] The two branches 18, 19 are connected to the rigid part 15, which forms the end of the terminal part 6 of the wound blades 2, by two pairs 31, 32 of parallel flexible blades, which form the elastic elements 17 of the clamp 23. Each pair 31, 32 of flexible blades is fitted on the one hand inside a large section 33, 34 of the L and on the other hand on the rigid part 15 of the terminal part 6. The pairs 31, 32 are preferably arranged symmetrically with respect to the terminal part 6, the blades being substantially perpendicular to the rigid part 15. The thin part 16 of the terminal part 6 passes between the small sections 27, 28 of the L, which are substantially perpendicular to the terminal part 6. The rigid part 15 of the terminal part 6 extends between the two large sections 33, 34 of the L. The rigid part 15 and the two large sections 33, 34 of the L are substantially parallel. The rigid member 14 is substantially perpendicular to the large sections 33, 34 of the L and to the rigid part 15 of the terminal part 6. Thus, when the rigid member 14 is pushed, the clamp is displaced along the end portion 6 due to the tilting of the pair 31 , 32 of flexible leaves.

[0044] For the third embodiment of spiral balance spring 20, branches 39, 41 of clamp 33 have the shape of a staircase, each branch comprising two levels, a first level 42, 43 and a second level 44, 45 connected by a portion 46 substantially perpendicular to the two levels. The first level 42, 43 of each branch 39, 41 is substantially parallel, and the second level 44, 45 of each branch 39, 41 is substantially parallel.

[0045] The first layers 42, 43 of each branch 39, 41 are closer to each other and are preferably flexible, while the second layers 44, 45 of each branch 39, 41 are further apart and are preferably rigid. The free end of each first layer 42, 43 comprises a protrusion 46, 47 bearing a bearing surface 48, 49, which extends perpendicularly to the second layer 44, 45 towards the terminal portion 6 of the wound blade 2. The terminal portion 6 extends between the two branches 39, 41 of the clamp 20, that is to say between the protrusions 46, 47, and between the first layer 42, 43 and the second layer 44, 45. The terminal portion 6 comprises a short thin portion 16 to allow the protrusions 46, 47 to be inserted into the cavities 55, 56 of the base position of the adjustment device. To adjust the effective length of the spiral balance spring, the branches 39, 41 are pushed so that the protrusions 46, 47 come out of their cavities and come into contact with the thicker part 57 of the terminal portion 6. The branches 39, 41 are offset from the terminal portion 6.

[0046] The flexible element 51 comprises two pairs 52, 54 of parallel flexible blades. Each pair 52, 54 is linked on the one hand to the second layer of each branch 39, 41, and to the rigid part 16 of the end portion 6. The blades of the same pair 52, 54 are substantially parallel, and the two pairs 52, 54 are symmetrical with respect to the rigid part 15 of the end portion 6. In this embodiment, there is no rigid member perpendicular to the end portion 6 on which the force is to be exerted. The force is applied to the second layer 44, 45, which is substantially colinear with the second layer 44, 45, so as to slide the clamp 3 along the end portion 6 and to make the protrusions 46, 47 come out of their cavities 55, 56.

[0047] The fourth and fifth embodiments of the spiral balance spring 30, 40 describe a fixture 63 comprising a rigid member 59 and two movable bodies 64, 65 bearing bearing surfaces 66, 67. The movable bodies 64, 65 have an elliptical shape extending toward the end portion 6. The fixture 63 comprises at least one flexible blade 68, 69, 83, 84 for connecting each movable body 64, 65 to the rigid member 59. The rigid member 59 has a U-shape, comprising a base section 77 and two parallel sections 78, 79. The inside of the U faces the movable bodies 64, 65. The ends of the parallel sections 78, 79 are straight, and the flexible blades are substantially straight. The flexible blades 68, 69 are arranged at the ends of each parallel section 78, 79 on the one hand, and on the movable bodies 64, 65 on the other hand. In the fourth embodiment, the two flexible blades 68 , 69 are substantially co-linear with the parallel sections 78 , 79 in the rest position, whereas the four flexible blades 83 , 84 of the fifth embodiment are inclined towards the end portion 6 .

[0048] The flexible element 62 comprises a translation platform 71 connected on the one hand to the rigid member 59 and on the other hand to the flexible wound blade 2 of the spiral balance spring 30. The translation platform 71 comprises at least one second flexible blade, preferably two second flexible blades 72, 73, and a rigid portion 74 to which one or more second flexible blades 72, 73 are joined by one end and by the other end to the rigid member 59. The second flexible blades 72, 73 are joined in parallel sections 79. The rigid portion 74 forms an elbow, here a right-angle elbow, which comprises two substantially perpendicular sections 81, 82. The end portion 6 of the wound blade is joined to the first section 81, while the second blade 72, 73 is joined to the second section 82. The end portion 6 is therefore substantially perpendicular to the one or more second flexible blades 72, 73 of the translation platform 71. Furthermore, the clamp 61 comprises two springs 75 , 76 , each of which is fastened on the one hand to the rigid part 74 of the translation platform 71 and on the other hand to a different movable body 64 , 65 .

[0049] Thus, when a force is applied to the rigid member 59, the movable bodies 64, 65 are displaced along the end portion 6. The translation platform 71 allows the position of the end portion 6 to remain substantially unchanged.

[0050] Of course, the invention is not limited to the embodiments described with reference to the accompanying drawings and variants may be envisaged without departing from the scope of the invention. The embodiment described shows a clamp whose bearing surface contacts the wound blade. According to a possible alternative embodiment, the bearing surface is kept at a distance from the wound blade, which contacts the bearing surface during operation of the resonator mechanism.

Claims

1. A spiral balance spring (1, 10, 20, 30, 40) for a timepiece resonator mechanism, the spiral balance spring (1, 10, 20, 30, 40) extending substantially in a plane and comprising a flexible blade (2) wound on itself with a number of turns and an adjustment device for varying the effective length of the wound blade (2), the adjustment device comprising a clamp (3, 23, 53) displaceable along at least one end portion (6) of the spiral balance spring (1, 10, 20, 30, 40) , 63), the clamp (3, 23, 53, 63) extending substantially in the plane of the spiral hairspring (1, 10, 20, 30, 40), the clamp (3, 23, 53, 63) comprising two bearing surfaces (4, 5, 24, 25, 48, 49, 66, 67) arranged in a variety of positions on both sides of the wound blade (2) in order to define a variable effective length of the spiral hairspring (1, 10, 20, 30, 40), characterized in that The clamp (3, 23, 53, 63) and the wound blade (2) are connected to each other by a flexible element (7, 17, 51, 87), thereby allowing the clamp (3, 23, 53, 63) and the support surface (4, 5, 24, 25, 48, 49, 66, 67) to be displaced along the wound blade (2).

2. The spiral hairspring according to claim 1, characterized in that: The clamp (3, 23, 53, 63) and the wound blade (2) are made in one piece.

3. The spiral hairspring according to claim 1 or 2, characterized in that: The wound blade (2) comprises a tip portion (6), and the bearing surface (4, 5, 24, 25, 48, 49, 66, 67) is configured to bear on both sides of the tip portion (6).

4. The spiral hairspring according to claim 3, characterized in that: The clamp (3, 23, 53) comprises two branches (8, 9, 18, 19, 39, 41) extending on both sides of the terminal portion (6) of the spiral balance spring, the end of each branch (8, 9, 18, 19, 39, 41) comprising one of the bearing surfaces (4, 5, 24, 25, 48, 49).

5. The spiral hairspring according to claim 4, characterized in that: The flexible element (7, 17, 51, 87) comprises at least two flexible blades (11, 12, 31, 32, 52, 54) connected on the one hand to the branches (8, 9, 18, 19, 39, 41) and on the other hand to the end portion (6) of the wound blade (2).

6. The spiral hairspring according to claim 5, characterized in that: In the rest position of the flexible element (7, 17, 51, 87), the flexible blades (31, 32, 52, 54) of the flexible element are substantially perpendicular to the end portion (6).

7. The spiral balance spring according to claim 5, characterized in that: The flexible blades (11, 12) of the flexible element partially surround the end portion (6).

8. The spiral hairspring according to claim 3, characterized in that: The clamp (63) comprises a rigid member (59) and two movable bodies (64, 65), each movable body comprising one of the bearing surfaces (66, 67).

9. The spiral balance spring according to claim 8, characterized in that: The flexible element (87) comprises at least two flexible blades (68, 69, 83, 84) to connect each movable body (64, 65) to the rigid member (59).

10. The spiral hairspring according to claim 8 or 9, characterized in that: The flexible element (87) comprises a translation platform (71) connected on the one hand to the clamp (63) and on the other hand to the end portion (6).

11. The spiral hairspring according to claim 10, characterized in that: The translation platform (71) includes at least one second flexible blade and a rigid part (74), one or more second flexible blades (72, 73) are connected to the rigid part (74) and the rigid member (59), and the end part (6) of the wrapped blade (2) is connected to the rigid part (74).

12. The spiral balance spring according to claim 11, characterized in that: The flexible element (87) comprises two springs (75, 76), each spring being connected at one end to the rigid part (74) of the translation platform (71) and at the other end to each movable body (64, 65).

13. The spiral hairspring according to claim 1 or 2, characterized in that: The bearing surface (4, 5, 24, 25, 48, 49, 66, 67) is configured to abut against the wound blade (2).

14. The spiral hairspring according to claim 1 or 2, characterized in that: The support surface is configured to maintain a certain distance from the wound blade (2).

15. The spiral hairspring according to claim 1, characterized in that: The clamp (3, 23, 53, 63) and the wound blade (2) are made of silicon.

16. The spiral balance spring according to claim 11, characterized in that: The translation platform (71) comprises two flexible blades.

17. A timepiece resonator mechanism comprising a balance wheel, characterized in that It comprises a spiral balance spring (1, 10, 20, 30, 40) according to any one of the preceding claims.

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