Assembly for attaching balance spring for horological movement, balance spring, and method for adjusting beat and rate of balance spring assembly

Abstract

To provide a mechanical assembly allowing secure attachment without resilient deformation of an outer last coil of a balance spring and without use of any adhesive.SOLUTION: An assembly for removable attachment of a balance spring 2 includes means 8 of retaining the balance spring 2 on one hand, and a removable locking part 10 on the other hand. A second free end 18 of an outer last coil 20 of the balance spring 2 includes attachment means in which the retaining means 8 is engaged to ensure the removable attachment of the balance spring 2 by the outer last coil 20. The attachment means is dimensioned such that, in its natural rest position, the balance spring 2 is not in contact with the retaining means 8 engaged with the attachment means. The locking part 10 for the removable attachment of the second free end 18 of the outer last coil 20 of the balance spring 2 is engaged with the retaining means 8 to lock the attachment means.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an assembly for mounting a hairspring for a timepiece movement. The present invention further relates to an adjustment method for such a mounting assembly. [Background technology]

[0002] In watchmaking, the hairspring is combined with a balance to form a regulating member commonly referred to as a hairspring balance for mechanical watches. At first glance, the hairspring takes the form of a very thin spring that is coiled around itself when unstressed. When mounted, the first end of the hairspring, called the inner first coil, is attached to a collet fitted to the balance staff, and the second end of the hairspring, called the outer final coil, is attached to a hairspring stud, a component typically attached to the balance bridge by a stud holder.

[0003] In particular, a time base for a mechanical timepiece, also called an oscillating system, includes a hairspring balance and an escapement. The balance consists of a balance staff pivoted between a first and a second bearing and connected to a balance fellow by a radial arm. The hairspring is attached to the balance staff via its inner first coil, for example by a collet, and is attached to a fixed attachment point, such as a hairspring stud carried by a stud holder, via its outer final coil.

[0004] In a very common embodiment, the escapement comprises a double roller system consisting of a large roller carrying an impulse pin and a small roller made hollow. The escapement further comprises a pallet lever, the pallet staff of which is pivoted between a first and a second bearing. The pallet lever comprises a lever connecting the forks to the inlet and outlet arms. The forks, consisting of an inlet horn and an outlet horn, carry the dart. The travel of the forks is limited by inlet and outlet banking pins, which may be made integral with the pallet bridge. The inlet and outlet arms carry the inlet and outlet pallets, respectively. Finally, the pallet lever cooperates with an escape wheel set, which comprises an escape wheel and an escapement pinion. This assembly formed by the escape wheel and the pinion is pivoted between a first and a second bearing.

[0005] The balance spring is a spring that assumes a spiral shape when at rest. Wound in a plane parallel to the plane of the clock movement, the balance spring performs a single function: to make the balance oscillate around its equilibrium position (also called the rest point) with as constant a frequency as possible. When the balance is moved away from its equilibrium position by a pivoting movement in a given direction, the balance spring contracts. This exerts a restoring torque on the balance spring that tries to return it to its equilibrium position. During this pulsation, the balance spring relaxes. However, since the balance has acquired a given speed and therefore kinetic energy, it will continue to move in the opposite direction until it has passed its equilibrium position and the restoring torque that the balance spring exerts on it stops it again and rotates it in the opposite direction.

[0006] The balance spring thus alternately expands and contracts, breathing, so to speak. However, during the expansion and contraction phases, many factors can play a role in preventing the balance spring from progressing isochronously. In particular, the balance spring must be resistant to oxidation and magnetism, which could cause the coils to stick together and impair the accuracy of the watch, or stop it completely. On the other hand, atmospheric pressure has little effect. Over time, temperature is the main issue, since heat causes metals to expand, while cold causes them to contract. The balance spring must therefore be elastic in such a way that it always returns to its original shape after any deformation.

[0007] The material used to manufacture balance springs is usually steel. Due to its ductility, the steel used must be resistant to corrosion. Developments over the last 20 years have also proposed to manufacture balance springs from silicon. Silicon balance springs are more accurate than steel balance springs, especially since they are less susceptible to magnetic fields. However, silicon balance springs are expensive, difficult to assemble, and prone to breaking.

[0008] The hairspring must be isochronous: no matter how far the balance is turned, the time it takes to oscillate must be the same. If the hairspring is contracted by only a few degrees, it will slowly return to its equilibrium position, accumulating very little energy. If the hairspring is moved far from its equilibrium position, it will move in the opposite direction very quickly. The important thing is that the two journeys take the same amount of time to complete. The basic idea is that the energy available to the hairspring is not constant, and whether the watch is fully wound or at the end of its power saving period, the hairspring must still function.

[0009] The balance spring is difficult to assemble due to its small dimensions. However, the manner in which the ends of the balance spring are attached also has a significant impact on the accuracy of the speed of the watch movement. In most mechanical movements, the ends of the balance spring are inserted into drilled parts and secured by pins that are forcibly assembled by hand using pliers. This causes the balance spring to rotate slightly, compromising the accuracy of the speed of the movement.

[0010] Another technique consists in attaching the ends of the balance spring using an adhesive. However, this technique also has its limitations. It has been observed that the adhesive, due to its viscosity, exerts a pulling force on the balance spring by capillary action, so that the ends of the balance spring can be pressed against the walls of the balance spring stud with which they engage. The resulting deformation of the balance spring induces mechanical stresses that are detrimental to maintaining a constant speed.

[0011] To remedy these problems, the Applicant has already proposed a method for mounting the hairspring, which consists in adhesively bonding the outer final coil of the hairspring in the stud using a drop of fluid adhesive that can be polymerized, for example, by UV irradiation: even if the free end of the final coil of the hairspring moves slightly under the influence of the weight of the adhesive drop when the adhesive drop is deposited, for example using a syringe-type adhesive dispenser, which induces undesirable mechanical stresses in the hairspring, the adhesive is sufficiently fluid before hardening to allow the free end of the final coil of the hairspring to return spontaneously to its rest position. The mechanical stresses induced by the hairspring when the liquid adhesive drop is deposited disappear by itself, and the consistency of the speed of the hairspring is not affected by the adhesive bonding effected thereon.

[0012] Thus, the above solution allows the mounting of the hairspring by the free end of its outer final coil in the stud, while eliminating all or at least most of the mechanical stresses that are usually induced in the hairspring during its assembly. This significantly improves the consistency of the speed of the hairspring. However, in use, the applicant has noticed that the hardened adhesive pad, which is formed when the droplets of liquid adhesive used to mount the free end of the outer final coil of the hairspring are polymerized, nevertheless tends to peel off from the stud from time to time. This of course leads to an immediate failure of the watch movement in which the hairspring is installed. Such a situation is due in particular to problems with the surface condition of the stud, which prevents the adhesive pad from completely adhering to the stud, but also to creep and ageing of the adhesive pad over time. Moreover, when the ambient temperature increases, most adhesives soften, which results in a change in the effective length and therefore in the stiffness of the hairspring, which has a negative effect on the speed of the watch movement.

[0013] Finally, it should be noted that, particularly in the case of the finest watch movements, the use of adhesives or synthetic products which are not compatible with the high level of finishing and expertise required for such watch movements is avoided as far as possible.

[0014] Patent document 1 is known as a hairspring for a hairspring-type balance assembly of a mechanical watch movement, the free end of the outer final coil of the hairspring includes an elastically deformable opening for receiving and clamping a hairspring stud-type mounting element. Preferably, the mounting element has a cylindrical shape with a circular cross section, which includes a flat area against which the free end of the outer final coil of the hairspring contacts to prevent the free end from rotating around the mounting element during the operation of the movement. The mounting element allows the free end of the outer final coil of the hairspring to be mounted without the need for additional mounting means such as pins or adhesives. Furthermore, by adjusting the position of the free end of the outer final coil of the hairspring relative to the mounting element, it is possible to adjust the height of this free end on the mounting element. This is made possible by the fact that the free end of the outer final coil of the hairspring frictionally engages with the mounting element. However, this is problematic. For example, in the event of a shock, there is a risk that the free end of the outer final coil will change position relative to its mounting element or even become dislodged from this mounting element. This will at best alter the accuracy of the speed of the balance spring balance assembly and at worst cause the watch to fail. It should also be noted that if the mounting of the outer final coil of the balance spring is ensured by frictional forces resulting from the elastic contact of the mounting element with an opening provided in the free end of the outer final coil of the balance spring, this does not guarantee the true durability of the balance spring, insofar as these frictional forces tend to be relaxed by time and wear. The frictional forces between the edge of the opening in the free end of the outer final coil of the balance spring and the mounting element will rapidly become insufficient to securely fix the balance spring to this mounting element. [Prior art documents] [Patent documents]

[0015] [Patent Document 1] European Patent Application Publication No. 1515200 Summary of the Invention

[0016] The object of the present invention is to alleviate these and other problems by providing a mechanical assembly which allows a hairspring for a timepiece movement to be securely mounted without elastic deformation of the outer end coil and without the use of adhesives, so that, if necessary, the hairspring can be disassembled and reassembled without risk of damage.

[0017] To this end, the invention relates to an assembly including a balance bridge for the removable mounting of a hairspring of a timepiece movement, the assembly including on the one hand a hairspring and on the other hand a means for holding the hairspring and a removable locking part, the hairspring including a coil winding extending between a first free end of an inner first coil and a second free end of an outer final coil, the second free end of the outer final coil of the hairspring having mounting means engaged by a holding means for releasably mounting the hairspring by said outer final coil, the mounting means being dimensioned such that in its natural reset position the hairspring does not come into contact with said holding means engaged with said mounting means, and a locking part ensuring the removable mounting of the second free end of the outer final coil of the hairspring is mounted on said holding means so as to lock the mounting means.

[0018] In a particular embodiment of the invention, the attachment means is an opening formed in the second free end of the outer final coil of the balance spring.

[0019] In a particular embodiment of the invention, the second free end of the outer final coil of the hairspring is formed with an opening and is made integral with the hairspring assembly.

[0020] In another particular embodiment of the invention, the opening is formed by a curved portion of the second free end of the outer final coil of the balance spring.

[0021] In yet another particular embodiment of the invention, the second free end of the outer final coil of the balance spring is provided with a plate formed with an opening.

[0022] In yet another particular embodiment of the invention, the plate is fixed to the second free end of the outer final coil of the balance spring.

[0023] In yet another particular embodiment of the invention, the plate is welded to the second free end of the outer final coil of the balance spring.

[0024] In yet another embodiment of the present invention, the opening is oval in shape.

[0025] In yet another embodiment of the present invention, the oblong opening has a major axis that is continuous with the outer final coil.

[0026] In yet another particular embodiment of the invention, the retaining means includes a post arranged in an opening formed in the second free end of the outer final coil of the balance spring.

[0027] In yet another particular embodiment of the invention, the post is made integral with the balance bridge of the clock movement.

[0028] In yet another particular embodiment of the invention, the retaining means includes a support member formed by a stud on which a post is mounted.

[0029] In yet another particular embodiment of the present invention, the support part is arranged in a recess formed in the balance bridge.

[0030] In yet another particular embodiment of the present invention, the support piece is arranged in the recess by a friction fit.

[0031] In yet another particular embodiment of the present invention, the support piece is screwed into the recess.

[0032] In yet another particular embodiment of the invention, a retaining piece is arranged between the balance bridge and the support piece to prevent accidental unscrewing of the support piece.

[0033] In yet another particular embodiment of the present invention, the retaining piece is a spring washer.

[0034] In yet another embodiment of the present invention, the locking component is a washer that is removably attached to the post.

[0035] In yet another embodiment of the present invention, the washer is pressed onto the post.

[0036] In yet another particular embodiment of the invention, a flexible element intended to modify the stiffness of the balance spring is arranged between the second free end of the outer final coil of the balance spring and a lever surrounding the coil winding and terminating in a plate formed with an opening.

[0037] The invention further relates to a method for adjusting the speed of a balance spring assembly mounted by a mounting assembly according to the invention, in which a mounting means included in the second free end of the outer final coil of the balance spring is engaged on a post of a support part, which is pivoted in one direction or the other, as required, until the post is no longer in contact with the mounting means of the balance spring, the beat of the balance spring assembly is adjusted by pivoting said balance spring assembly around the balance staff until the impulse pin of the balance roller is aligned with the escapement line passing through the balance staff and the pallet staff, then once the adjustment of the beat of the balance spring assembly is completed, it is again ensured that the post of the support part does not come into contact with the mounting means of the balance spring, and if applicable, the support part is again rotated to move the post away from the mounting means of the balance spring, and then a removable locking part is attached to the post to lock the second free end of the outer final coil of the balance spring.

[0038] The invention further relates to a method for adjusting the speed of a hairspring balance assembly in which a hairspring is mounted by means of a mounting assembly according to the invention, in which a removable locking part is mounted on a post to lock the second free end of the outer final coil of the hairspring, and the second free end of the outer final coil of the hairspring is then driven by pivoting the support part clockwise or counterclockwise.

[0039] Thanks to these characteristics, the invention gives an assembly which allows the mounting in a removable and replaceable manner of the hairspring of a timepiece movement without the aid of adhesives, and which ensures the immobilization of the free end of the outer final coil of the hairspring, without inducing mechanical stresses in said hairspring, in particular in the plane in which the windings of the coils of said hairspring extend, so as not to affect the regularity of the speed of the timepiece movement. [Brief description of the drawings]

[0040] Other characteristics and advantages of the invention will become apparent from the following detailed description of one embodiment, given by way of non-limiting example only with reference to the accompanying drawings, in which:

[0041] [Figure 1] FIG. 1 is a general perspective view of an assembly for removably mounting a hairspring of a timepiece movement, in its simplified embodiment. [Diagram 2] FIG. 1 is a general perspective view of an assembly for removably mounting a hairspring of a timepiece movement, in an improved embodiment thereof; [Diagram 3] FIG. 3 is a top view of a silicon balance spring including a first flexible arm and a second flexible arm used in the mounting assembly of FIG. [Figure 4] 1 is a perspective view of a hairspring, the outer final coil of which is integrally provided with a plate, the plate having an opening for receiving a post. [Diagram 5]FIG. 1 is a perspective view of a hairspring with a plate attached to the free end of the outer final coil of the hairspring, the plate being formed with an opening for receiving a post. [Figure 6] 1 is a perspective view of a balance spring, the outer final coil of which is curved to form an opening that receives a post. [Figure 7] FIG. 1 is a schematic diagram showing the case where the post is made integral with the balance bridge of the watch movement. [Figure 8] FIG. 13 is a schematic diagram showing the case where the retaining means includes a support part formed by a stud having a post mounted thereon, the stud being aligned by friction fitting into a recess formed in the balance bridge. [Figure 9] This shows the case where the retaining means includes a support member formed by a stud with a post mounted thereon, arranged in a recess formed in the balance bridge by screwing with a washer interposed between the balance bridge and the support member to prevent accidental unscrewing. [Figure 10] FIG. 1 is a perspective view of a balance spring, the outer final coil of which is curved to form a hook that receives a post. [Figure 11] Figures 11 and 12 respectively show, assembled and disassembled, a case in which the retaining means is arranged in the form of a support piece placed in a recess formed in the balance bridge, the outer final coil of the balance spring being capped by a locking piece provided with a post which is received in an opening formed in the support piece. [Figure 12] Figures 11 and 12 respectively show, assembled and disassembled, a case in which the retaining means is arranged in the form of a support piece placed in a recess formed in the balance bridge, the outer final coil of the balance spring being capped by a locking piece provided with a post which is received in an opening formed in the support piece. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] The invention is derived from the general original idea of ​​providing a mechanical assembly that allows the second free end of the outer final coil of a hairspring for a hairspring balance assembly of a timepiece movement to be attached without the use of adhesive. By making it possible to dispense with the use of adhesives, the invention avoids the problems associated with such materials, in particular in terms of ageing and creep, as well as in terms of image. In particular, it is clearly seen that the desire is to avoid, as far as possible, the need to resort to assembling mechanical parts using adhesives, in particular in the field of high-end watches. According to another of its advantages, the mechanical assembly according to the invention allows the second free end of the outer final coil of the hairspring to be attached in a removable manner, so that the position of the hairspring can be readjusted if necessary, even when the watch is returned to the workshop. Another advantage of the mechanical assembly according to the invention is that it allows the second free end of the outer final coil of a hairspring for a timepiece movement to be attached without mechanical stresses being induced at this second end, in particular in the plane in which the coil windings forming the hairspring extend. This is highly favorable in terms of the speed accuracy of the hairspring balance assembly.

[0043] The mounting assembly according to the present invention, generally referred to by the general reference number 1, is intended for removable mounting of a hairspring 2 of a timepiece movement including a balance bridge 4.

[0044] In particular, as shown in FIG. 1, the mounting assembly 1 includes a balance spring 2 as well as a retaining means 8 and a removable locking element 10 .

[0045] As can be seen from FIG. 1, the hairspring 2 comprises a coil winding 12 extending between a first free end 14 of the inner first coil 16 and a second free end 18 of the outer final coil 20. According to the invention, the second free end 18 of the outer final coil 20 of the hairspring 2 comprises a mounting means in the form of an opening 22 in a preferred and non-limiting embodiment of the invention, in which a holding means 8 is engaged to ensure a removable mounting of the hairspring 2 by its outer final coil 20. The opening 22 is dimensioned such that, in the natural rest position of the hairspring 2, an edge 24 of this opening 22 does not come into contact with the mechanical mounting means 8 engaged in this opening 22. That is to say, the mounting of the hairspring 2 by the mounting assembly 1 according to the invention does not induce any stresses in this hairspring 2 in the XY plane in which it extends, i.e. without affecting the accuracy of the speed. A removable locking part 10 is intended to ensure a removable attachment of the second free end 18 of the outer final coil 20 of the hairspring 2 and is engaged, preferably by pushing, with means 8 which follow and hold the hairspring 2.

[0046] According to a particular embodiment of the invention, the opening 22 provided in the second free end 18 of the outer final coil 20 of the hairspring 2 is preferably, but not limited to, oval in shape, and the main axis 26 extends continuously through the outer final coil 20 (see FIG. 3 ).

[0047] In the embodiment shown in FIGS. 4 to 6, the opening 22 is oval in shape with a radius of curvature R centered about the center 27 of the coil winding 12 .

[0048] The opening 22 can be embodied in a variety of ways.

[0049] In one embodiment of the invention, the second free end 18 of the outer final coil 20 of the hairspring 2 is formed with an opening 22 and is made integral with the hairspring 2 assembly. That is to say, the outer final coil 20 of the hairspring 2 can be provided with an integrally made plate 28 with an opening 22 formed therein (FIG. 4). Conversely, the plate 28 can be attached to the second free end 18 of the outer final coil 20 of the hairspring 2 by a joining process, for example welding (FIG. 5). It is also possible that the opening 22 is formed by a curved portion 30 of the second free end 18 of the outer final coil 20 of the hairspring 2 (FIG. 6).

[0050] The retaining means 8 includes a post 32 arranged to engage an opening 22 formed in the second free end 18 of the outer final coil 20 of the balance spring 2 .

[0051] In a first embodiment, the post 32 is made integral with the balance bridge 4 of the clock movement (FIG. 7).

[0052] According to another embodiment of the invention, the retaining means 8 comprises a support part 34 formed by a stud 36 on which the post 32 is mounted. This support part 34 is arranged in a recess 38 formed in the balance bridge 4. The support part 34 is positioned in the recess 38 either by friction fit (figure 8) or by screwing (figure 9). When the support part 34 is screwed into the recess 38, the support part 34 is externally threaded and the recess 38 is complementary threaded in its inner wall 40. To prevent accidental unscrewing of the support part 34, a retaining part 42 such as a spring washer may be arranged between the balance bridge 4 and the support part 34 (figure 9).

[0053] The removable locking component 10 is a washer that is removably attached to a post 32, typically by a press fit.

[0054] In its simplified embodiment, the mounting assembly 1 according to the invention allows adjusting the beat of the balance spring assembly 44. Moreover, in its preferred embodiment, the mounting assembly 1 according to the invention allows not only to adjust the beat of the balance spring assembly 44 but also to adjust the speed of such balance spring assembly 44.

[0055] As already mentioned above, the mounting assembly 1 according to the invention is first mounted by engaging the opening 22 provided in the second free end 18 of the outer final coil 20 of the hairspring 2 with the post 32 of the support part 34. Usually, the entire mechanical assembly formed by the hairspring 2, the hairspring balance assembly 44 comprising said hairspring 2 and the holding means 8 is dimensioned such that, when the post 32 of the support part 34 is engaged in the opening 22 of the hairspring 2, the edge 24 of the opening 22 of the hairspring 2 does not come into contact with the post 32 engaged in said opening 22. However, in the rare event that this is not the case, the invention advantageously allows the support part 34 to be pivoted slightly in one direction or the other until the post 32 is no longer in contact with the edge 24 of the opening 22 of the hairspring 2. The beat of the balance spring assembly 44 is then adjusted by rotating it around the balance staff 46 until the impulse pin 48 of the balance roller 50 is aligned with the escapement line passing through the balance staff 46 and the pallet staff (not shown in the drawings). Once the adjustment of the beat of the balance spring assembly 44 is completed, it is again ensured that the post 32 of the support part 34 is not in contact with the edge 24 of the opening 22 of the balance spring 2. As mentioned above, in the extremely unlikely event that this is not the case, the invention allows to rotate the support part 34 again to move the post 32 away from the edge 24 of the opening 22 of the balance spring 2, and then drives the washer onto the post 32 to lock the second free end 18 of the outer final coil 20 of the balance spring 2. In the opposite case, i.e. when no contact is found between the edge 24 of the opening 22 of the hairspring 2 and the post 32 of the support part 34 , the hairspring 2 can be directly locked by attaching a washer to the post 32 .

[0056] It is of course understood that if the support part 34 is made integral with the balance bridge 4, it cannot be pivoted.

[0057] In a preferred embodiment of the invention shown from the perspective view in Fig. 2, it is possible to adjust not only the beat of the balance spring assembly 44 but also the speed of this balance spring assembly 44. The operation of adjusting the speed of the balance spring assembly 44 is performed after the second free end 18 of the outer final coil 20 of the balance spring 2 has been locked by mounting a washer on the post 32. At this point, the support part 34 is pivoted clockwise or counterclockwise, thereby driving the second free end 18 of the outer final coil 20 of the balance spring 2.

[0058] In detail, Figure 3 shows that the hairspring 2 comprises a flexible element 52 consisting of a pivot 54 including a first non-intersecting flexible blade 56 and a second non-intersecting flexible blade 58, and a rigid part 60. The first flexible blade 56 and the second flexible blade 58 are joined on the one hand laterally to an elongated fixed support part 62 and on the other hand to the pivot 54 by moving towards each other, i.e. the flexible blades 56, 58 move towards each other from the fixed support part 62 to the pivot 54. The fixed support part 62 is attached to a mounting part 62a integral with the bridge 4. The second free end 18 of the outer final coil 20 of the hairspring 2 is joined to the pivot 54. In the drawing, a variable torque is exerted on an additional blade 63 connecting the outer final coil 20 to the rigid part 60, thereby modifying the stiffness of this additional blade and, as a result, the stiffness of the balance spring 2 and thus the speed of the balance spring balance assembly 44. To this end, the balance spring 2 is stretched beyond its flexible element 52 by a lever 64 which bypasses the coil winding 12. The lever 64 terminates in a plate 28 provided with an opening 22 according to the invention. The torque is transmitted to the balance spring 2 via the lever 64 and the flexible element 52. For a complete description of the balance spring 2 used in this improved embodiment of the invention, reference is made to European Patent Application No. 21202213.1 filed by the Applicant.

[0059] Needless to say, the present invention is not limited to the embodiments just described, and various simple modifications and alternative embodiments can be envisaged by those skilled in the art without departing from the scope of the invention as defined by the appended claims.

[0060] The post 32 can be made integral with the balance bridge 4. If the support part 34 is a separate part that is attached by a press fit in a recess 38 machined in the balance bridge 4, the support part 34 can be pivoted both clockwise and counterclockwise. When the support part 34 is pivoted, the post 32 is also pivoted, so that this post 32 does not come into contact with the edge 24 of the profile of the opening 22 made in the free end 18 of the outer final coil 20 of the balance spring 2. That is to say, the balance spring 2 can be placed spontaneously in its natural rest position without mechanical stress. This is the most favorable solution for the speed accuracy of the balance spring balance assembly 44.

[0061] Typically, the balance spring 2, especially if made of silicon, is manufactured to very tight tolerances, so that the position of the geometric centre of the opening 22 made in the free end 18 of the outer final coil 20 of the balance spring 2 is known very accurately in advance. This makes it possible to accurately position the post 32 in the balance bridge 4, or alternatively to position the support piece 34 corresponding to the assembly formed by the stud 36 and the post 32, in a recess 38 provided in the balance bridge 4 for this purpose.

[0062] If the hairspring 2 is made of silicon, the free end 18 of the outer final coil 20 of the hairspring 2, in which the opening 22 is formed, is made integral with the hairspring 2 assembly. If the hairspring 2 is made of a metal alloy, the opening 22 for receiving the post 32 of the support part 34 can be formed by simply bending the free end 18 of the outer final coil 20 of the hairspring 2. It is also possible to attach, typically by welding, to the free end 18 of the outer final coil 20 of the hairspring 2, a plate 28 in which the opening 22 for receiving the post 32 of the support part 34 is formed.

[0063] In the extremely unlikely event that, after installation of the hairspring 2 and engagement of the post 32 in the opening 22 provided in the free end 18 of the outer final coil 20 of the hairspring 2, it is observed that the edge 24 of this opening 22 comes into mechanical contact at any point with the post 32, the invention advantageously allows the support part 34 to be pivoted until no mechanical contact is observed any more. That is to say, whatever the circumstances, the invention makes it possible to guarantee immobilization of the free end 18 of the outer final coil 20 of the hairspring 2 without inducing stresses in the XY plane in which the hairspring 2 extends. This is highly advantageous for the accuracy of the speed of the hairspring balance assembly 44.

[0064] In a simplified alternative embodiment of the invention, there is a single attachment point of the free end 18 of the outer final coil 20 of the balance spring 2. That is, the post 32 of the support piece 34 engaged in an opening 22 formed in the free end 18 of the outer final coil 20 of the balance spring 2 acts as a balance spring stud, and thus only the beat of the balance spring assembly 44 can be adjusted.

[0065] In an improved alternative embodiment of the invention, there are two attachment points and the hairspring 2 is preferably made of silicon. In this case, there are two attachment points and both the pulsation and the speed of the hairspring balance assembly 44 can be adjusted. Furthermore, thanks to the invention, it is understood that the speed of the hairspring balance assembly 44 can be fine-tuned in different ways, for example by modifying the inertia of the balance, by adding or removing material, or by screwing in or unscrewing weights. It is also possible to adjust the speed of the hairspring balance assembly 44 by modifying the stiffness of the hairspring 2 according to the invention. Some hairspring balance assemblies can also be adjusted in both ways simultaneously.

[0066] The stud 36 of the support part 34 may be threaded to allow fine adjustment of its height along an axis Z perpendicular to the support surface provided by the support part 34. To prevent the threaded support part 34 from being accidentally removed, a retaining part 42, for example of the spring washer type, may be arranged between the threaded support part 34 and the surface of the balance bridge 4 to lock the threaded stud 36. Thanks to the invention, it is possible to adjust the speed rate of the balance spring balance assembly 44 by changing the stiffness of the balance spring 2 attached to the balance staff 46 by means of a collet 66. This is much easier than adjusting the speed of the balance spring balance assembly by modifying the inertia of the balance, for example by adding or removing material or by moving weights, screws, etc.

[0067] According to a particular embodiment of the invention shown in Fig. 10, the attachment means may have an open geometry, for example in the form of a hook 68, into which a retaining means 8 engages to ensure a removable attachment of the hairspring 2 by its outer final coil 20. This retaining means 8 is of the type of post 32, which is arranged in the internal space bounded by the hook 68 and is held in place by a retaining part 42. Normally, when the hairspring 2 is fitted, there should be no mechanical contact between the hook 68 and the post 32. If this is not the case, however, the support part 34 may be rotated until no mechanical contact is found.

[0068] According to a particular embodiment of the invention, the holding means 8 comprises a support piece 70 arranged in a recess 72 formed in the balance bridge 4. The support piece 70 is arranged in the recess 72 either by friction fit or by screwing. The free end 18 of the outer final coil 20 of the balance spring 2 rests on this support piece 70 and is capped by a locking piece 74 provided on its underside with a post 76 which is received in an opening 78 made in the support piece 70. [Explanation of symbols]

[0069] 1 Mounting Assembly 2. Hairspring 4 Balance cock 8. Means of retention 10 Removable locking parts 12 Coil Winding 14 1st free end 16 Inner first coil 18 Second free end 20 Outer final coil 22 Aperture 24 Edge 26 Spindle 27 center 28 Plate 30 Curved Section 32 Posts 34 Support parts 36 Studs 38 Recess 40 Inner Wall 42 Retaining parts 44 Hairspring balance assembly 46 Balance Staff 48 Impulse pin 50 Balance Roller 52 Flexible elements 54 Axis 56 First flexible blade 58 Second flexible blade 60 Rigid parts 62 Fixed support 62a Mounting parts 63 Additional Blade 64 Lever 66 Colette 68 Hook 70 Support parts 72 Recess 74 Lock parts 76 Posts 78 Aperture

Claims

1. An assembly (1) for the removable mounting of a hairspring (2) of a timepiece movement including a balance bridge (4), comprising: said assembly comprising on the one hand a retaining means (8) for said balance spring (2) and on the other hand a removable locking part (10); The hairspring (2) includes a coil winding (12) extending between a first free end (14) of an inner first coil (16) and a second free end (18) of an outer final coil (20); a second free end (18) of the outer final coil (20) of said hairspring (2) comprising mounting means with which said retaining means (8) are engaged to ensure a removable mounting of said hairspring (2) with its outer final coil (20); said attachment means being dimensioned such that in its natural rest position it is not in contact with said holding means (8) engaged therewith; Assembly (1), wherein the locking part (10) for releasably attaching the second free end (18) of the outer final coil (20) of the hairspring (2) is mounted on the holding means (8) for locking the attachment means.

2. 2. An assembly (1) for mounting a hairspring (2) according to claim 1, characterized in that the mounting means is an opening (22) provided in the second free end (18) of the outer final coil (20) of the hairspring (2).

3. 3. An assembly (1) for mounting a hairspring (2) according to claim 2, characterized in that said opening (22) is oval in shape and has a main axis (26) continuous with said outer final coil (20).

4. 2. An assembly (1) for mounting a hairspring (2) according to claim 1, characterized in that the second free end (18) of the outer final coil (20) of the hairspring (2), in which the opening (22) is formed, is made integral with the hairspring (2) assembly.

5. 2. An assembly (1) for mounting a hairspring (2) according to claim 1, characterized in that said opening (22) is formed in a curved portion (30) of the second free end (18) of the outer final coil (20) of said hairspring (2).

6. 2. An assembly (1) for mounting a hairspring (2) according to claim 1, characterized in that the second free end (18) of the outer final coil (20) of the hairspring (2) is provided with a plate (28) in which the opening (22) is formed.

7. 7. An assembly (1) for mounting a hairspring (2) according to claim 6, characterized in that said plate (28) is fixed to the second free end (18) of the outer final coil (20) of said hairspring (2).

8. 8. An assembly (1) for mounting a hairspring (2) according to claim 7, characterized in that said plate (28) is welded to the second free end (18) of the outer final coil (20) of the hairspring (2).

9. 2. An assembly (1) for mounting a hairspring (2) according to claim 1, characterized in that the means (8) for holding comprises a post (32; 76) arranged to engage in an opening (22) provided in the second free end (18) of the outer final coil (20) of the hairspring (2).

10. 10. Assembly (1) for mounting a hairspring (2) according to claim 9, characterized in that said post (32) is made integral with the balance bridge (4) of the clock movement.

11. 10. An assembly (1) for mounting a hairspring (2) according to claim 9, characterized in that the means for holding (8) comprise a support part (34) formed by a stud (36) on which the post (32) is mounted.

12. Assembly (1) for mounting a balance spring (2) according to claim 11, characterized in that the support part (34) is arranged in a recess (38) formed in the balance bridge (4).

13. Assembly (1) for mounting a hairspring (2) according to claim 12, characterized in that said support part (34) is arranged in said recess (38) by means of a friction fit.

14. Assembly (1) for mounting a hairspring (2) according to claim 12, characterized in that said support part (34) is screwed into said recess (38).

15. 15. An assembly (1) for mounting a hairspring (2) according to claim 14, characterized in that a retaining piece (42) is arranged between the balance bridge (4) and the support piece (34) to prevent accidental unscrewing of the support piece (34).

16. Assembly (1) for mounting a hairspring (2) according to claim 15, characterized in that the retaining part (42) is a spring washer.

17. 10. An assembly (1) for mounting a hairspring (2) according to claim 9, characterized in that the locking part (10) is a washer removably mounted on the post (32).

18. Assembly for mounting a hairspring according to claim 17, characterized in that said washer is pressed onto said post (32).

19. 10. An assembly according to claim 9, characterized in that the means for holding (8) comprises a support part (70) arranged in a recess (72) formed in the balance bridge (4) and capped by a locking part (74) provided with a post (76) received in an opening (78) formed in the support part (70).

20. 2. An assembly for mounting a hairspring according to claim 1, characterized in that a flexible element (52) arranged to modify the stiffness of the hairspring (2) is arranged between the second free end of the outer final coil of the hairspring and a lever (64) surrounding the coil winding (12), the opening (22) being provided in the free end of the lever (64).

21. A method for regulating the beat of a balance spring assembly including a balance spring (2) mounted by a mounting assembly according to claims 1 and 11, comprising the steps of: the second free end (18) of the outer final coil (20) of the hairspring (2) includes an attachment means which is engaged with a post (32) of the support part (34); said support part (34) is pivoted in one direction or the other, as required, until said post (32) is no longer in contact with the mounting means of said balance spring (2); a method in which the beat of the balance spring assembly (44) is adjusted by pivoting the balance spring assembly (44) about the balance staff (46) until the impulse pin (48) of the balance roller (50) is aligned with an escapement line passing through the balance staff and the pallet staff, then once the adjustment of the beat of the balance spring assembly (44) is completed, it is ensured that the post (32) of the support part (34) does not come into contact again with the mounting means of the balance spring (2), and if applicable, the support part (34) is rotated again to move the post (32) away from the mounting means of the balance spring (2), and then the removable locking part (10) is pressed into the post (32) to lock the second free end (18) of the outer final coil (20) of the balance spring (2).

22. A method for adjusting the speed of a hairspring balance assembly (44), comprising the steps of:

2. The method according to claim 1, wherein the hairspring of the hairspring balance assembly (44) is mounted by the mounting assembly according to claim 1, and the removable locking part (10) is pressed into the post (32) to lock the second free end (18) of the outer final coil (20) of the hairspring (2), and then the support part (34) is pivoted clockwise or counterclockwise to drive the second free end (18) of the outer final coil (20) of the hairspring (2).

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