Clock device with balance wheel-hairspring with means for adjusting the running

Abstract

The timekeeping device according to the invention comprises a frame, a resonator, and a resonator rate adjustment device (17). The resonator includes a balance wheel mounted on a shaft pivoted within the frame and a balance spring (7) serving as a return spring for the balance wheel. The balance spring (7) comprises a coiled elastic blade (9) extending from an inner end (10) fixed to the shaft to an outer end (11) fixed to the frame, and an elastic element (13) joined to the outer coil of the coiled elastic blade (9) at at least one junction point (14), on which the adjustment device (17) can act directly or indirectly. The at least one junction point (14) is separated from the outer end (11) by an elastic portion (15) of the outer coil. The adjustment device (17) is arranged to deform the wound elastic blade (9) via the elastic element (13) so as to apply a radial force to the shaft and thus modify the operation of the resonator.

Description

[0001] The present invention relates to a balance-spring clockwork device. The clockwork device is, for example, a clock movement, a part of a clock movement, a module intended to be mounted on a clock movement, or a tourbillon or carousel.

[0002] In mechanical watchmaking, the balance wheel and hairspring constitute a timekeeping unit known as a resonator. Its oscillations are maintained and counted by an escapement driven by a mainspring barrel. The oscillating and inertial component of the balance wheel and hairspring is the balance wheel itself. It is mounted on a shaft whose ends (the "pivots") are supported by bearings within a frame. The hairspring is the balance wheel's return spring. It comprises a spirally wound elastic leaf, the inner end of which is fixed to the shaft by a ferrule, and the outer end of which is fixed to the frame, specifically to a balance bridge within the frame, by means of a stud.

[0003] For the watch's accuracy, it is important to be able to regulate the resonator's rate. Rate traditionally refers to the difference between two states of the watch or resonator separated by a given time interval, typically a 24-hour interval – this is then called "diurnal rate". It is also possible to measure an instantaneous rate µ, reported over a 24-hour period, and therefore expressed in seconds per day (s / d), as a function of the balance wheel's oscillation period: μ = − 86400 T − T 0 T where T is the observed period of the balance wheel, T0 is the theoretical (desired) period of the oscillations, and 86400 is the number of seconds in 24 hours. To regulate the timekeeping, watchmakers can adjust the inertia of the balance wheel and / or the stiffness of the balance spring. The inertia of the balance wheel can, for example, be adjusted by turning weights or regulating screws located on the balance wheel rim. By operating a lever called a regulator, the active length of the balance spring, and therefore its stiffness, can also be modified.

[0004] Patent application EP 4009115 A1 describes a balance spring whose stiffness can be adjusted in a different way. This spring comprises a flexible ribbon or blade wound in several turns and a flexible element arranged in series with the ribbon, thus connecting the outer end of the ribbon to a fixed support. Preload means are arranged to vary the stiffness of the flexible element, and therefore the overall stiffness of the balance spring, without changing the position of the outer end of the ribbon. This solution, however, only allows for fine adjustment and, in practice, must be combined with an adjustment of the balance wheel's inertia to provide the watchmaker with a sufficient range for adjusting the timekeeping.

[0005] The present invention aims to propose an alternative solution for adjusting the operation of a resonator, the adjustment range of which can be particularly large.

[0006] To this end, a clockwork device according to claim 1 is provided, particular embodiments being defined in the dependent claims.

[0007] The present invention also provides a timepiece, for example a watch, as defined in claim 9 and an adjustment method as defined in claim 10.

[0008] Other features and advantages of the present invention will become apparent from the following detailed description, made with reference to the accompanying schematic drawings, in which: there figure 1 is a partial cross-sectional view of a timekeeping device according to the invention; the figure 2 is a view of a spiral forming part of the watchmaking device according to the invention, this spiral being shown in its resting state (non-oscillating) and without any adjustment constraint; the figure 3 is a view of the same spiral at rest (non-oscillating) but after the application of a regulating force; the figure 4 is a view of the same spiral at rest (non-oscillating) but after the application of a regulating force in the opposite direction to that of the figure 3 ; there figure 5 is a diagram of the radial force, in newtons, applied to the shaft on which a balance wheel of the clockwork device is mounted, as a function of time during the oscillations of the balance wheel, for three different regulating forces; the figure 6 is a diagram of the instantaneous rate, in seconds / day, of the balance wheel and hairspring (in horizontal position) as a function of the balance wheel's oscillation amplitude, in degrees, for eleven different regulating forces; the figures 7 à 13 are views of variants of the spiral forming part of the watchmaking device according to the invention.

[0009] With reference to the figure 1 A watchmaking device according to the invention, for a timepiece such as a watch, in particular a wristwatch, comprises a frame 1 and a resonator 2 mounted in the frame 1. In the example shown, the frame 1 is that of the movement of the timepiece and therefore constitutes a fixed part of the timepiece. The frame 1 comprises a plate 3 and bridges fixed to the plate 3, notably a balance bridge 4. Between the plate 3 and the balance bridge 4 is the resonator 2, comprising a balance wheel 5, a shaft 6 with axis A on which the balance wheel 5 is mounted, and a balance spring 7 serving as a return spring for the balance wheel 5. The pivots of the shaft 6 are arranged to rotate in bearings 8 which are respectively provided by the plate 3 and the balance bridge 4.

[0010] Spiral 7 includes (cf. figure 2 ) a main part consisting of a coiled elastic blade 9 extending from an inner end 10 to an outer end 11. The inner end 10 is joined to a ferrule 12 mounted on the shaft 6 and is thus integral with the balance wheel 5. The outer end 11 is fixed in a conventional manner to the frame 1, more precisely to the balance bridge 4, by means of a pin (not shown).

[0011] The spiral 7 further comprises an elastic element 13 joined to the outer coil of the wound elastic blade 9 at a junction point 14 and which, like the wound elastic blade 9, deforms during the oscillations of the balance wheel 5. The junction point 14 is distant from the outer end 11; in other words, it is separated from this outer end 11 by an elastic portion 15 of the outer coil. In the example of the figure 2 The elastic element 13 is a bent blade extending from the junction point 14 to a free end 16, the portion between the junction point 14 and the bend extending radially with respect to the axis A of the shaft 6. The elastic element 13 is preferably in one piece with the wound elastic blade 9, and preferably the spiral 7 is in one piece with the ferrule 12. The spiral 7 is for example made of silicon, preferably coated with a layer of silicon oxide, and is obtained for example by a method involving deep reactive ion etching.

[0012] The free end 16 of the elastic element 13 is fixed during normal operation of the resonator 2 but cooperates with an adjusting device 17 that can be operated by a watchmaker, typically using a tool. Thus, when setting the watch movement, the free end 16 can be moved as indicated by the double arrow on the figure 2 so as to move, by means of the elastic element 13, the junction point 14 in the radial direction with respect to the axis A, or in a direction close to the radial direction, in at least one of the two directions and preferably in both directions.

[0013] Such a displacement of the junction point 14 pushes (cf. figure 3 ) or pull (cf. figure 4 ) the outer coil in said radial direction, which deforms the whole of the wound elastic blade 9 and causes the latter to apply a radial force on the shaft 6 via the ferrule 12 and to cause in reaction the generation of a radial counter-force from the bearings 8 on the shaft 6. This radial force, the intensity of which depends on the value of the displacement of the junction point 14 by the adjusting device 17, is added to the variable (periodic) radial force which the shaft 6 applies to the bearings 8 during the oscillations of the balance wheel 5 due to the eccentric development of the balance spring 7.

[0014] There figure 5 shows the total radial counterforce applied by the bearings 8 to the shaft 6 during the oscillations of the balance wheel 5 for different adjustment values, namely a zero value (middle curve: the adjustment device 17 exerts no force on the elastic element 13), a positive value (top curve: the adjustment device 17 has pushed the outer coil, as illustrated in the figure 3 ) and a negative value (bottom curve: the adjusting device 17 has pulled the outer coil, as illustrated in the figure 4 ). It is observed that the main effect of the adjustment is to move the radial force / counter-force curve upwards or downwards depending on the direction of movement of the junction point 14 by the adjustment device 17, that is to say, to add a constant positive or negative radial force to the periodic radial force due to the eccentric development of the spiral 7.

[0015] Modifying the radial force / counter-force on the shaft 6 and the bearings 8 has a direct effect on the operation of the resonator 2. Indeed, for any balance wheel and balance spring, the radial force is a perturbation that can be translated into an operation µ 1, in seconds per day (s / d), expressed as a function of the amplitude θ 0 of the balance wheel: μ 1 θ 0 = 86400 2 πθ 0 2 ∫ 0 2 π dX dθ θ φ θ φ dφ where: θ is the elongation of the pendulum relative to its equilibrium position: θ(φ) = θ 0 cos φ and: X θ = 1 σ 2 Δ θ 2 σ being the radius of gyration of the spiral and Δ(θ) being the displacement of the geometric center of the spiral (located on the axis of rotation of the balance wheel) during the contractions and expansions of the spiral in a theoretical situation where this geometric center is free, the axis of the balance wheel not being held by any bearing, the outer end of the spiral being taken as a fixed reference point.

[0016] The value Δ(θ) of the displacement of the balance spring's geometric center in the theoretical situation where this geometric center is free is directly related to the radial force applied in practice to the shaft on which the balance wheel is mounted and which pivots in bearings. Therefore, adding a constant radial force to the shaft is equivalent to adding a constant value to the displacement Δ(θ) in the formulas above, which allows for adjusting the resonator's rate.

[0017] There figure 6 The diagram shows the rate of the resonator 2 as a function of the amplitude of the balance wheel 5 for different adjustment values ​​corresponding to positions of the free end 16 of the elastic element 13 from its rest position of -0.5 mm, -0.4 mm, -0.3 mm, -0.2 mm, -0.1 mm, 0 mm, +0.1 mm, +0.2 mm, +0.3 mm, +0.4 mm, and +0.5 mm, for a distance between the axis A and the free end 16 of 3 mm when the adjustment value is 0 mm. A remarkable feature is the large range of rate adjustment (more than 70 seconds per day) that can be achieved using the adjustment method proposed by the invention. This large rate adjustment range makes it possible, for example, to eliminate the balance wheel inertia adjustment elements (weights or adjusting screws) and to adjust the rate by acting only on the balance spring.

[0018] Preferably, in order to increase the intensity of the radial force communicated to the shaft 6 by the adjusting device 17 for a given adjustment value, the elastic portion 15 of the outer coil separating the junction point 14 from the outer end 11 extends over an angle of at least 50°, preferably at least 100°, preferably at least 150°, preferably at least 200°, this angle being measured from the axis A and when the spiral 7 is at rest and the adjusting device 17 exerts no force on the elastic element 13.

[0019] The radial force applied to the balance staff by a balance spring during the balance wheel's oscillations varies in intensity and direction (periodically), but remains oriented in a substantially constant direction. For example, it is known that in the case of a balance spring fixed to the staff by a rigid ferrule, the direction of the radial force is that of the line passing through the inner and outer ends of the spring. In the case of a flexible ferrule, the direction of the radial force is modified but remains substantially constant.In the present invention, preferably, the radial force resulting from the adjustment is oriented substantially in the same direction as the variable radial force received by the shaft 6 during the oscillations of the balance wheel 5 when the adjustment device 17 exerts no force on the elastic element 13, or is oriented in a direction that differs from that of said variable radial force by a maximum of ±40°, preferably a maximum of ±30°, preferably a maximum of ±20°, preferably a maximum of ±10°. This avoids altering the isochronism of the resonator, as reflected in the curves of the [equation missing]. figure 6 which all have approximately the same slope. The isochronism can also be adjusted by thickening, or otherwise stiffening, a portion 18 of the inner coil of the spiral 7 and / or by winding the elastic blade 9 with a variable pitch, as illustrated in the figure 2 . We can also thicken, or otherwise stiffen, a portion 19 of the outer coil to adjust the isochronism and / or prevent coils from touching during the operation of the resonator 2. We can also wind the elastic blade 9 according to a variable pitch in order to prevent the coils from touching during operation.

[0020] The adjusting device 17 may include any type of adjusting element used in watchmaking, for example an eccentric or a screw-nut system acting on the elastic element 13 directly or indirectly, for example via a lever.

[0021] It should be noted that, unlike the solution proposed in patent application EP 4009115 A1, the stiffness of the spiral 7 is very little modified by the action of the adjustment device 17, the bulk of the change in rate being due to the disturbance caused by the addition of a radial force.

[0022] The present invention is not limited to the example shown in the figure 2 According to other embodiments, the elastic element 13 may include a blade bent in the opposite direction ( figure 7 ), a simple straight radial blade ( figure 8 ), two blades meeting ( figure 9 ), three blades meeting ( figure 10 ), a blade in the shape of a circular arc ( figure 11 ), a blade defining three sides of a rectangle ( figure 12 ) or a helical or other type spring ( figure 13 In the case of figures 9 à 12The elastic element 13 has several points of junction with the outer loop. Preferably, the one of these points of junction which is closest to the outer end of the wound elastic blade is separated from this outer end by an elastic portion of the outer loop extending over an angle of at least 50°, preferably at least 100°, preferably at least 150°, preferably at least 200°, this angle being measured as defined previously.

[0023] Furthermore, according to other embodiment examples, the free end 16 and the outer end 11 fixed to the frame 1 could be connected by an arrangement of rigid and elastic parts made in one piece with the spiral 7 and the adjustment device 17 could act on this arrangement rather than directly on the free end 16.

Claims

1. A horological device comprising a frame (1), a resonator (2) and a resonator (2) rate adjustment device (17), the resonator (2) comprising a balance wheel (5) mounted on a shaft (6) pivoted in the frame (1) and a balance spring (7) serving as a return spring for the balance wheel (5), the balance spring (7) comprising a coiled elastic blade (9) extending from an inner end (10) fixed to the shaft (6) to an outer end (11) fixed to the frame (1) and an elastic element (13) joined to the outer coil of the coiled elastic blade (9) at at least one point of junction (14) and on which the adjustment device (17) can act directly or indirectly, characterized in that at least one junction point (14) is separated from the outer end (11) by an elastic portion (15) of the outer loop and in thatThe adjustment device (17) is arranged to deform the coiled elastic blade (9) via the elastic element (13) so as to apply a radial force to the shaft (6) and thus modify the operation of the resonator (2).

2. Clockmaking device according to claim 1, characterized in that said elastic portion (15) extends over an angle of at least 50°, preferably at least 100°, preferably at least 150°, preferably at least 200°, this angle being measured from the axis (A) of the shaft (6) and when the spiral (7) is at rest and the adjusting device (17) exerts no force on the elastic element (13).

3. Clockmaking device according to claim 1 or 2, characterized in thatsaid radial force is oriented substantially in the same direction as a radial force of variable intensity received by the shaft (6) during the oscillations of the rocker (5) when the adjusting device (17) exerts no force on the elastic element (13), or is oriented in a direction which differs from that of said radial force of variable intensity by a maximum of ±40°, preferably a maximum of ±30°, preferably a maximum of ±20°, preferably a maximum of ±10°.

4. A clockwork device according to any one of claims 1 to 3, characterized in that the elastic element (13) is a single blade.

5. Clockmaking device according to claim 4, characterized in that said single blade is angled.

6. A clockwork device according to any one of claims 1 to 3, characterized in that the elastic element (13) comprises several blades.

7. A clockwork device according to any one of claims 1 to 6, characterized in thatThe adjustment device includes an eccentric or a screw-nut system.

8. A clockwork device according to any one of claims 1 to 7, characterized in that The spiral is a single piece.

9. Timepiece comprising a timekeeping device according to any one of claims 1 to 8.

10. A method for adjusting a watchmaking device according to any one of claims 1 to 8, characterized in that It includes a step of measuring the walk of the resonator (2) and a step of actuating the adjustment device (17) according to the result of the measurement of said walk.

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