Balance spring for horological regulating member provided with temperature-dependent adjustment means

Abstract

To provide a balance spring for a horological regulating member, the balance spring being provided with temperature-dependent adjustment means.SOLUTION: The present invention relates to a balance spring, in particular, for a horological regulating member, the balance spring (100) including a flexible strip (2) wound about its own axis multiple turns, the strip (2) having a predefined stiffness. The balance spring (100) has means of adjusting the stiffness of the strip (2) The balance spring (1) also has actuating means (10) for actuating the adjustment means, the actuating means (10) being configured to actuate the adjustment means depending on ambient temperature. The invention also relates to a horological regulating member including such balance spring.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a hairspring for a timepiece speed regulating member, the hairspring comprising adjustment means that are temperature-dependent. The present invention further relates to a timepiece speed regulating member comprising such a hairspring.

Background Art

[0002] In most mechanical watches, the energy required for the rotation of the hands (for example, the minute hand and the hour hand) is stored in a barrel and then delivered by a hairspring-wheel system, which comprises a ratchet wheel called a wheel, and the wheel is combined with a spring in the form of a strip wound in a spiral shape called a hairspring.

[0003] The inner end of the hairspring is attached to the fusee that rotates the hairspring together with the wheel, and the outer end of the hairspring is attached to the hairspring holder, which is assembled on the hairspring holder support, and the hairspring holder support itself is rigidly connected to a fixed stud.

[0004] The rotation of the wheel is maintained by an escapement mechanism, and the vibrations of the wheel are counted. The escapement mechanism comprises an anchor lever driven by a low-amplitude oscillatory movement, and the anchor lever comprises two anchors that engage with the teeth of the escape wheel. When the escape wheel engages in this way, the escape wheel is rotated step by step, and the number of rotations of the escape wheel is determined by the frequency of oscillation of the anchor lever. The anchor lever itself is set to the frequency of oscillation of the hairspring-wheel.

[0005] In a conventional escapement mechanism, the frequency is about 4 Hz, or about 28,800 vibrations per hour (V / h). One of the aims of excellent watch manufacturers is to ensure the isochronism and regularity of the vibrations of the wheel (or the stability of the speed of the wheel).

[0006] The speed of the balance wheel can be adjusted in a known manner by adjusting the effective length of the hairspring. The effective length of the hairspring is defined as the length of the curve between the inner end of the hairspring and the counting point, located near the outer end of the hairspring, and is typically defined by a pair of stops supported by a key assembled on the regulator system.

[0007] During operation, this regulator system cannot rotate about the axis of the hairspring. However, the angular position of the regulator system can be finely adjusted by human intervention, for example, by using a screwdriver to pivot an eccentric that acts like a cam on the regulator system.

[0008] An assembly comprising a bolt, a regulator system, a key, a hairspring holder, a hairspring, a balance, a spring, and a balance wheel is generally referred to as a "speed regulating member". Examples of speed regulating members are shown in both International Publication No. WO 2016 / 192957 filed by watch manufacturer ETA and European Patent Application Publication No. EP 2876504.

[0009] There is a regulator system having a hairspring holder to which the ends of the hairspring are attached, and the key of the regulator system leaves a play such that the hairspring can move between two stops. However, the timekeeping characteristics, particularly the non-isochronism that varies according to the amplitude, are quite sensitive to the play of the key of the regulator, and it is difficult to accurately control this play.

[0010] In some devices, the stops can be adjusted to hold the hairspring, especially to eliminate the play during the operation of the hairspring. In this case, first, the speed is adjusted by moving the key of the regulator, and then the hairspring is clamped to the key. However, clamping the hairspring to the key of the regulator causes stress on the hairspring, especially the center of the winding is displaced, which may lead to errors in timekeeping. Furthermore, removing the play also changes the speed, and once the hairspring is clamped, it is no longer possible to move the key of the regulator along the hairspring to complete the fine adjustment of the speed.

[0011] Other hairspring mechanisms have an integrated speed regulation device. In these hairspring mechanisms, speed regulation is not achieved 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. More specifically, the flexible element is placed in series with the strip between the end of the strip and the fixed support, modifying the rigidity of the attachment point and making the resonator more flexible. Thus, the effective rigidity of the resonator includes the rigidity of the strip and the rigidity of the flexible element.

[0012] In this case, a variable force or torque is applied so as to apply stress to the flexible element. By applying stress to the flexible element, the rigidity of the flexible element, from which a return force acting on the escapement wheel is partially obtained, changes while the rigidity of the strip remains unchanged. By modifying the rigidity of the flexible element, the overall rigidity of the resonator (the rigidity of the strip and the rigidity of the flexible element) changes, and as a result, the speed of the resonator is modified, enabling accurate adjustment of the frequency of the time reference. Since only one element is used for rigidity adjustment, this brings high accuracy during speed regulation.

[0013] Such a hairspring mechanism with an elastic element is described, for example, in European Patent Application Publication No. 4009115 filed by Omega SA.

[0014] However, the ambient temperature significantly affects the speed of the speed regulation member comprising such a hairspring mechanism and a balance wheel. This is because the escapement wheel and / or the hairspring expand or contract according to the ambient temperature. These dimensional variations bring about variations in the speed of the speed regulation member.

[0015] Furthermore, since the elastic coefficient also changes according to the ambient temperature, the rigidity of the hairspring is changed.

[0016] In order to reduce these variations, a speed control member configured to compensate for the influence of temperature has been developed. For example, when using a bimetal tension ring or in the case of a silicon hairspring, a silicon oxide layer having a thermal expansion coefficient opposite to that of the silicon from which the hairspring is made is added (see European Patent No. 1422436).

[0017] However, these configurations are effective only around a predefined specific temperature and are no longer sufficiently effective when the temperature deviates from this specific temperature.

Prior Art Documents

Patent Documents

[0018]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0019] An object of the present invention is to overcome some or all of the above-mentioned drawbacks by providing a hairspring with effective adjustment means, in particular, to minimize the sensitivity of the speed control member to changes in ambient temperature, and this adjustment means adapts to the ambient temperature even when the temperature variation is significant.

Means for Solving the Problems

[0020] For this purpose, the present invention relates in particular to a hairspring for a speed regulating member of a timepiece, the hairspring comprising a flexible strip wound a plurality of times around its own axis, the strip having a predefined stiffness, the hairspring comprising means for adjusting the stiffness of the strip, and the hairspring comprising actuating means for actuating the adjusting means.

[0021] The present invention is characterized in that the actuating means actuates the adjusting means as a function of the ambient temperature.

[0022] Thanks to the actuating means, variations in the dimensions of the hairspring and / or the balance wheel due to temperature, as well as thermoelastic variations of the hairspring, are compensated for, and in particular, the secondary influence of temperature on the speed of the speed regulating member is compensated for. Thus, variations in the speed of the speed regulating member comprising the hairspring and the escapement wheel resulting from temperature variations are prevented.

[0023] According to a particular embodiment of the present invention, the actuating means comprise a deformable element dependent on temperature.

[0024] According to a particular embodiment of the present invention, the deformable element comprises a temperature-sensitive material.

[0025] According to a particular embodiment of the present invention, the deformable element is a bimetallic addition.

[0026] According to a particular embodiment of the present invention, the deformable element comprises a microstructure or even a nanostructure.

[0027] According to a particular embodiment of the present invention, the actuating means comprise a support that can be moved by the deformable element and that moves the support to a plurality of positions as a function of the deformation of the deformable element.

[0028] According to a particular embodiment of the present invention, the adjusting means comprise a flexible element arranged in series with the strip, the flexible element connecting one end of the strip to a fixed support so as to add further stiffness to the strip, and the flexible element preferably having a stiffness exceeding that of the strip.

[0029] According to a particular embodiment of the invention, the adjusting means comprises stress applying means for applying a variable force or torque to the flexible element in order to vary the stiffness of the flexible element.

[0030] According to a particular embodiment of the invention, the support is in contact with the stress applying means.

[0031] According to a particular embodiment of the invention, the support comprises a rod which has a first end assembled on the deformable element and a second end assembled on the stress applying means.

[0032] According to a particular embodiment of the invention, the actuating means comprises a fixing pin enabling the rod to form a lever.

[0033] According to a particular embodiment of the invention, the flexible element comprises two flexible parts, each of the two flexible parts connecting a strip to a fixed support, and the two flexible parts are arranged axially symmetrically with respect to each other along an axis which preferably substantially passes through the center of the hairspring.

[0034] According to a particular embodiment of the invention, the stress applying means comprises two flexible levers respectively connected to the flexible parts.

[0035] According to a particular embodiment of the invention, the two levers are connected to each other by a movable body.

[0036] The invention further relates to a speed regulating member, in particular for a timepiece movement, the speed regulating member comprising an oscillating weight and such a hairspring.

[0037] The objects, advantages and features of the invention are provided by way of example only and will become apparent by reading some embodiments shown with reference to the accompanying drawings. Some embodiments are not intended to limit the scope of the invention.

Brief Description of the Drawings

[0038]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0039] FIGS. 1 to 3 schematically show the first embodiment of the beard spring 1 for a chronograph speed control member, respectively. The three figures show three different configurations of the beard spring 1.

[0040] In this case, the beard spring 1 extends substantially in one plane. The beard spring 1 includes a flexible strip 2 wound around its own axis a plurality of times, and the strip 2 has a predefined rigidity.

[0041] The beard spring includes means for adjusting the rigidity of the strip 2. For example, the adjusting means can be actuated particularly when assembling the beard spring into the speed control member, especially when assembling it onto the plate of the chronograph movement.

[0042] The adjusting means comprises a flexible element 5 arranged in series with the strip 2, the flexible element 5 connecting the outer end 4 of the strip 2 to a fixed support 53 and being integral with the outer end 4 of the strip 2. The flexible element 5 adds further rigidity to the rigidity of the strip 2. The flexible element 5 is preferably stiffer than the strip 2. The flexible element 5 is arranged connected to the strip 2 behind the strip 2. Preferably, the adjusting means 5 and the strip 2 are an integral part or are further made of the same material. The moustache spring 1 further comprises stress applying means 6 for applying a variable force or torque to the flexible element 5. Thus, the rigidity of the moustache spring 1 can be adjusted, in particular to improve the accuracy of the movement speed.

[0043] In this embodiment of the moustache spring, the flexible element 5 comprises two flexible parts 15, 16 each connecting the strip 2 to the fixed support 53.

[0044] The two flexible parts 15, 16 are arranged axially symmetrically with respect to each other along the axis A of the moustache spring 1. In other words, the two flexible parts 15, 16 are arranged to be symmetric with respect to the axis A.

[0045] On the one hand, the axis A substantially passes through the center O of the moustache spring, and on the other hand, the axis A preferably passes through the outer end 4 of the strip 2.

[0046] Accordingly, the two flexible parts 15, 16 are arranged on the outer peripheral part of the moustache spring so that the two flexible parts 15, 16 are arranged at the same distance from the center O of the moustache spring 1.

[0047] The two flexible parts 15, 16 are preferably arranged in a "mirror-like" position with respect to each other with respect to the axis A. For this purpose, the two flexible parts 15, 16 are preferably substantially identical.

[0048] The flexible components 15, 16 each include a curved flexible blade 55, which preferably forms a semi-circle and extends from the end of the fixed support 53. Each curved flexible blade 55 is also connected to the outer end 4 of the strip 2 by the main flexible blade 7. In this case, the main flexible blade 7 is arranged continuously with the curved flexible blade 55.

[0049] The curved blade 55 forms a semi-circular curved portion and extends at one end by a single flexible blade 7 and at the other end by a fixed support 53. The end 56 of the support itself forms a complementary curved portion opposite to the curved portion of the curved blade 55. The end 56 of the support 53 is semi-rigid so that it can be partially deformed.

[0050] This configuration of the curved portion and the complementary curved portion can prevent the isochronism of the speed regulating member from being corrected when using the adjusting means to correct the speed. More specifically, the force applied to the upper part of the curved blade 55 is compensated by the reaction force of the complementary curved portion of the end 56, as shown by the arrow in FIG. 14. Therefore, only the single flexible blade 7 receives the force or torque applied by the stress applying means 6.

[0051] The fixed support 53 has an open trapezoidal shape on its long side facing the outer end 4 of the strip 2.

[0052] The means for adjusting the torsion spring 1 further includes stress applying means 6 for applying a variable force or torque to the flexible element 5. In this way, the rigidity of the torsion spring 1 can be adjusted. The torque or force is continuously adjustable for the stress applying means 6. In other words, the torque or force is not limited to a one-time value. Therefore, the rigidity of the flexible element 5 can be adjusted with great accuracy.

[0053] Preferably, the stress applying means 6 applies substantially the same force or torque to each flexible component 15, 16 through two levers 14, 26 by a single force F applied to the third body 19. The direction of the force is preferably substantially symmetric with respect to the axis A.

[0054] The stress application means 6 further includes two levers 14, 26. The two levers 14, 26 each connect the curved blades 55 to the same, preferably rigid, movable body 19. The movable body 19 is arranged on the opposite side of the torsion spring 1 with respect to the fixed support 53. In this case, the movable body 19 is in an arc shape.

[0055] A variable force or torque is applied to the movable body 19. The variable force or torque is at least partially transmitted to the main flexible blades 7 of the flexible parts 15, 16 of the flexible element 5 via the levers 14, 26.

[0056] Preferably, the torque or force is continuously adjustable thanks to the stress application means 6. In other words, the torque or force is not limited to a one-time value. Therefore, the rigidity of the flexible element 5 can be adjusted with great precision.

[0057] The torsion spring 1 further includes an actuating means 10 for actuating the stress application means 6.

[0058] According to the present invention, the actuating means 10 actuates the stress application means 6 according to the ambient temperature. Therefore, the actuating means 10 acts on the torsion spring 1 and makes it possible to compensate for the influence of the temperature change of the governor member by modifying the rigidity in order to maintain the governor member at a constant speed.

[0059] For this purpose, the actuating means 10 includes an element 11 that can deform according to temperature. The deformable element 11 has the advantage of deforming according to temperature in a controlled manner.

[0060] In an alternative embodiment, the deformable element 11 comprises a deformable liquid or semi-liquid element such as mercury or alcohol, for example used in a thermometer. This liquid or semi-liquid element is housed in a housing with a movable wall, and the movable wall moves in response to the deformation of the liquid or semi-liquid element that changes according to temperature.

[0061] Alternatively, the deformable element 11 is a metal that is highly sensitive to temperature.

[0062] The actuating means 10 further comprises a stress applying means 6 and, in this case, a support 12 that contacts the movable body 19. The support 12 also contacts the deformable element 11. Accordingly, the support 12 is movable by the deformable element.

[0063] For example, if the deformable element is a liquid or semi - liquid, the support 12 contacts a movable wall, thereby moving the support 12 in response to the deformation of the deformable element 11.

[0064] In the case of a metallic material, the support 12 contacts the metallic material directly.

[0065] In the drawing, the support 12 comprises a rod 13 that forms a lever with respect to the stress applying means 6. The rod 13 has two ends 17, 18. The first end 17 is assembled on the deformable element 11, and the second end 18 is assembled with respect to the stress applying means 6.

[0066] The actuating means 10 further comprises a pin 21, which is intended to remain stationary with respect to the base of the speed regulating member, and the rod 13 can contact the pin 21. The pin 21 acts as a support point, enabling the rod to form a lever. The pin 21 also forms a reference point for the speed of the speed regulating member.

[0067] The pin 21 is, for example, located approximately in the middle of the rod 13. Accordingly, when the rod 13 contacts the pin 21, the rod 13 leans against the pin 21 and transmits the force brought about by the deformation of the deformable element 11.

[0068] Preferably, the pin 21 has a non - circular cross - section for adjusting the actuation of the deformable element 11.

[0069] In FIG. 1, the rod 13 contacts the movable body 19 of the stress applying means 6 and leans on the pin 21. The rod 13 applies a force to the movable body 19 so as to obtain a predetermined rigidity of the hairspring 1. For example, the predetermined rigidity is selected for an ambient temperature of 20 degrees.

[0070] In an alternative embodiment, the pin 21 is offset from the center of the rod 13 so as to have a greater stress center distance when operating the rod 13.

[0071] In the configuration shown in FIG. 2, the deformable element 11 has expanded as a result of the higher temperature. The deformable element 11 pushes back the rod 13, and the rod 13 is no longer in contact with the pin 21. As the force applied to the moving body 19 increases, the stiffness of the flexible element 5 is changed.

[0072] Thus, the effect of the temperature rise on the speed control member is compensated by an increase in the force applied on the stress applying means 6.

[0073] In the configuration shown in FIG. 3, the ambient temperature has dropped and the deformable element is contracting. As a result, not only does the rod 13 return to the pin 21, but the moving body 19 is also pushed back due to the lever action. More specifically, since the rod presses the pin 21, the second end will press the moving body 19 of the stress applying means 6.

[0074] As a result, the stiffness of the flexible element 5 is modified to compensate for the effect of the ambient temperature drop on the speed control member.

[0075] In either case, regardless of whether the ambient temperature drops or rises, the actuating means 10 presses the moving body 19 so as to modify the stiffness of the flexible element 5.

[0076] In FIG. 4, the graph shows three superimposed curves 22, 23, 24 and shows the influence of temperature on the speed of the speed control member.

[0077] The lower curve 24 represents the variation in speed that changes with temperature in the case where there is no compensation according to the present invention. Thus, when the temperature increases or decreases, the difference in speed compared to the speed at 23 °C decreases. Such a curve can be achieved with the hairspring described in patent EP1605182.

[0078] The upper curve 22 represents the speed fluctuations obtained by the operating means 10 according to the present invention.

[0079] The middle curve 23 represents the effect obtained on the speed of the speed regulating member by the operating means 10 according to the present invention when the ambient temperature fluctuates. The speed remains almost constant despite significant temperature fluctuations.

[0080] More specifically, thanks to the operating means 10, the action of the operating means 10 shown by the upper curve 22 compensates for the influence of the temperature fluctuations shown by the lower curve 24 and keeps the speed almost constant despite the temperature difference.

[0081] The second embodiment of the moustache spring 1 is shown in FIG. 5. Except for the deformable element 27 of the adjusting means 10, the moustache spring 1 is almost the same as the first embodiment. In this case, the deformable element 27 comprises a bimetal addition that deforms according to temperature.

[0082] The bimetal addition is curved and has a first end 29. The first end 29 is assembled to a fixed support 31 outside the moustache spring 1. The second end 28 of the bimetal addition is associated with the first end 17 of the rod 12. The second end 28 of the bimetal addition is in contact with the first end 17 of the rod 12.

[0083] As the ambient temperature changes, the bimetal addition bends, albeit to a varying degree. Thus, the second end 28 of the bimetal addition pushes and pulls the first end 17 of the rod 12, activating the stress applying means 6.

[0084] As a result, depending on the curvature of the bimetal addition, the rod 13 moves in the same way as the rod 13 in the first embodiment.

[0085] Such bimetal additions are well known to those skilled in the art.

[0086] In the third embodiment shown in FIG. 6, the deformable element 28 includes a microstructure or nanostructure that deforms according to temperature, such as a honeycomb structure. Such a microstructure or nanostructure is configured to deform in the same manner as the deformation in the first embodiment.

[0087] As a result, according to the deformation of the microstructure or nanostructure, the rod 13 moves in the same manner as the rod 13 in the first embodiment.

[0088] The flexible blades described in various embodiments of the beard spring can be continuous flexible blades or blades having a flexible collar connecting rigid sections, as is typical in the drawings.

[0089] The present invention further relates to a speed control member (not shown), particularly for a timepiece movement. The speed control member includes, for example, a vibrating weight and the above-described beard spring. The vibrating weight is, for example, an annular balance wheel. The vibrating weight is joined to the beard spring such that the vibrating weight is integral with the support.

Description of Symbols

[0090] 1 Beard spring 2 Flexible strip 4 End 6 Stress applying means 9 End 10 Actuating means 11 Deformable element 12 Support 13 Rod 14 Flexible lever 15 Flexible part 16 Flexible part 17 First end 18 Second end 19 Movable body 21 Fixed pin 26 Flexible lever 53 Fixed support

Claims

1. A hairspring, particularly for a timepiece speed regulating member, wherein said hairspring (1) comprises a flexible strip (2) wound around its own axis a plurality of times, said strip (2) having a predefined stiffness, said hairspring (1) comprising means for adjusting the stiffness of said strip (2), said hairspring (1) comprising actuating means (10) for actuating said adjusting means, characterized in that said actuating means (10) actuates said adjusting means in response to the ambient temperature.

2. The hairspring according to claim 1, characterized in that said actuating means (10) comprises an element (11) deformable in response to the ambient temperature.

3. The hairspring according to claim 2, characterized in that said deformable element (11) comprises a temperature-sensitive material.

4. The hairspring according to claim 2, characterized in that said deformable element (11) comprises a bimetallic additive.

5. The hairspring according to claim 2, characterized in that said deformable element (11) comprises a microstructure or nanostructure.

6. The hairspring according to claim 2, characterized in that said actuating means (10) comprises a support (12), said support (12) being movable by said deformable element (11) and moving said support (12) to a plurality of positions in response to the deformation of said deformable element (11).

7. The hairspring according to claim 2, characterized in that said adjusting means comprises a flexible element (5) arranged in series with said strip (2), said flexible element (5) connecting the ends (4, 9) of said strip (2) to a fixed support (53) so as to add further stiffness to said strip (2), said flexible element (5) preferably having a stiffness exceeding that of said strip (2).

8. The hairspring according to claim 7, characterized in that said adjusting means comprises stress applying means (6) for applying a variable force or torque to said flexible element (5) so as to change the stiffness of said flexible element (5).

9. The hairspring according to claim 8, characterized in that said support (12) is in contact with said stress applying means (6).

10. The support (11) comprises a rod (13), the rod (13) having a first end (17) assembled on the deformable element (12) and a second end (18) assembled on the stress applying means (6), the eyebrow spring according to claim 9, characterized in that.

11. The actuating means (10) comprises a fixing pin (21) enabling the rod (13) to form a lever, the eyebrow spring according to claim 9, characterized in that.

12. The flexible element (5) comprises two flexible parts (15, 16), each of the two flexible parts (15, 16) connecting the strip (2) to the fixed support (53), the two flexible parts (15, 16) being arranged axially symmetrically with respect to each other along an axis (A), the axis (A) preferably substantially passing through the center (O) of the eyebrow spring, the eyebrow spring according to claim 7, characterized in that.

13. The stress applying means (6) comprises two flexible levers (14, 26) each connected to the flexible part (15, 16), the eyebrow spring according to claim 11, characterized in that.

14. The two levers (14, 26) are connected to each other via a movable body (19), the eyebrow spring according to claim 13, characterized in that.

15. A speed regulating member, particularly for a timing movement, comprising a vibrating weight, the speed regulating member being characterized in that it comprises the eyebrow spring (1) according to claim 1.

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