Assembly for attaching hairspring of timepiece movement, hairspring and method for adjusting deflection and travel time difference of hairspring balance assembly

Abstract

The invention relates to an assembly (1) for detachably attaching a hairspring (2) of a timepiece movement comprising a balance plate (4), comprising, on the one hand, the hairspring (2) comprising a coil winding (12) extending between a first free end (14) of a first inner ring (16) and a second free end (18) of an outermost ring (20), and a retaining structure (8) for the hairspring (2) and a detachable locking member (10). The second free end (18) of the outermost ring (20) of the hairspring (2) comprises an attachment structure in which the retaining structure (8) engages to ensure that the hairspring (2) is detachably attached through its outermost ring, the attachment structure being dimensioned such that, in its natural rest position, the hairspring is not in contact with the retaining structure engaged in the attachment structure, and in its natural rest position, the hairspring is not in contact with the retaining structure engaged in the attachment structure. A locking member for removably attaching the second free end of the outermost ring of the hairspring engages on the retaining structure to lock the attachment structure.

Description

Technical Field

[0001] The present invention relates to an attachment assembly for attaching a balance spring of a timepiece movement and also to an adjustment method for such an attachment assembly. Background Art

[0002] In the field of watchmaking, the balance spring in combination with the balance wheel forms the regulating mechanism for a mechanical timepiece, usually called a balance-spike assembly. At first glance, the balance spring is in the form of a very thin spring that winds itself into a coil when no stress is applied to it. When mounted, the first end of the balance spring (called the first inner coil) is attached to the stud mounted on the balance staff, and the second end of the balance spring (called the outermost coil) is attached to the balance spring stud, which is usually attached with the help of a stud holder in the balance cock.

[0003] More specifically, the time base (also called oscillating system) of a mechanical timepiece comprises a balance-spring assembly and an escapement. The balance comprises a balance staff pivoted between a first bearing and a second bearing and connected to the balance rim by means of radial arms. The balance spring is attached to the balance staff by means of its first inner turn, for example by means of a stud, and to a fixed attachment point, for example to a balance spring stud carried by a stud holder, by means of its outermost turn.

[0004] In a very common embodiment, the escapement mechanism includes a double disc system, which is composed of a large disc and a small disc, the large disc is provided with an impact nail and the small disc is formed with a notch. The escapement mechanism also includes a pallet fork, the pallet fork shaft of which pivots between a first bearing and a second bearing. The pallet fork is composed of a lever, which connects the fork head to the entry arm and the exit arm. The fork head is composed of an entry corner and an exit corner and is provided with a fork head nail. The travel of the fork head is limited by an entry limit nail and an exit limit nail, which can be made integral with the pallet fork splint. The entry arm and the exit arm carry the entry fork stone and the exit fork stone respectively. Finally, the pallet fork cooperates with the escape wheel set, which includes an escape wheel plate and an escape pinion, and the assembly formed by the escape wheel plate and the escape pinion pivots between the first bearing and the second bearing.

[0005] A hairspring is a spring that takes the form of a spiral when at rest. Wound in a plane parallel to the plane of the watch movement, the hairspring has one sole function: to make the balance oscillate around its equilibrium position (also called rest point) with as constant a frequency as possible. When the balance leaves its equilibrium position by pivoting in a given direction, the hairspring contracts. This generates a restoring torque in the hairspring that returns the balance to its equilibrium position. During this oscillation, the hairspring expands. However, as the balance acquires a certain speed and therefore kinetic energy, it overshoots its equilibrium position in the opposite direction until the restoring torque exerted by the hairspring on the balance stops it again and forces it to rotate in the opposite direction.

[0006] The hairspring thus alternately expands and contracts: this is known as breathing. However, during both expansion and contraction, many factors prevent the hairspring from expanding synchronously. In particular, the hairspring is subject to oxidation and magnetism, which can cause the coils to stick together and ruin the watch's precision or even stop it completely. Atmospheric stress, on the other hand, has little effect. Temperature has long been the main problem, since heat expands metals and cold contracts them. The hairspring must therefore be elastic so that it can deform but always return to its original shape.

[0007] The material used to make a hairspring is usually steel. The steel used is ductile and must be corrosion-resistant. Developments over the past two decades have also proposed making hairsprings from silicon. Silicon hairsprings have a higher rate of accuracy than steel hairsprings, especially because they are insensitive to magnetism. However, they are more expensive and more difficult to assemble because they are fragile.

[0008] The hairspring must be isochronous. It must always take the same amount of time to oscillate, no matter how far the balance wheel rotates. If the hairspring contracts only a few degrees, it builds up very little energy and returns slowly to its equilibrium position. If the hairspring moves away from its equilibrium position, it moves very quickly in the opposite direction. It is important that both trips take the same amount of time to complete. The basic idea is that the energy available to the hairspring is not constant, and it must still function regardless of whether the watch is fully wound or in the last hours of its power reserve.

[0009] Due to its small size, the assembly of the hairspring is very difficult. However, the way the two ends of the hairspring are attached also has a great influence on the timekeeping accuracy of the watch movement. In most mechanical watch movements, both ends of the hairspring are inserted into a component with a hole and fixed with the help of a pin, which is then manually forced together with pliers. This causes the hairspring to rotate slightly, which impairs the timekeeping accuracy of the movement.

[0010] Another technique is to attach the end of the balance spring using an adhesive. However, this technique also has its limitations. It has been observed that due to its viscosity, the adhesive exerts a tensile force on the balance spring through capillary action and can press the end of the balance spring against the wall of the balance spring stud, with which the end of the balance spring engages. The resulting deformation of the balance spring generates mechanical stress in the balance spring, which is not conducive to maintaining consistent timekeeping.

[0011] In order to solve these problems, the applicant has proposed a method for attaching a balance spring, which method consists in gluing the outermost winding of the balance spring inside the stud by means of a drop of polymerizable liquid adhesive, for example by means of ultraviolet radiation. Thus, even if the free end of the last winding of the balance spring moves slightly under the weight of the drop of adhesive, for example by means of a syringe-type adhesive dispenser, thus inducing undesirable mechanical stresses in the balance spring, the adhesive has sufficient fluidity before hardening to allow the free end of the last winding of the balance spring to spontaneously return to its rest position. Thus, the mechanical stresses induced in the balance spring when depositing the drop of liquid adhesive disappear on their own, and the consistency of the balance spring's running is not affected by the gluing operation performed thereon.

[0012] The above solution thus allows the hairspring to be attached inside the stud by the free end of its outermost coil, while eliminating all or at least most of the mechanical stresses that would normally be induced in such a hairspring during the assembly of such a hairspring. This greatly improves the consistency of the hairspring's travel time. However, during use, the applicant still realized that the hardened adhesive block formed when the liquid adhesive droplets used to attach the free end of the outermost coil of the hairspring polymerize sometimes falls off the stud, which of course causes the watch movement with the hairspring installed to fail immediately. This situation is particularly due to the surface condition of the stud, which causes the adhesive block to not adhere well to the stud, and due to the creep and aging of the adhesive block over time. In addition, when the ambient temperature rises, most adhesives soften, thereby changing the effective length of the hairspring, and thus changing the stiffness of the hairspring, thus negatively affecting the travel time of the watch movement.

[0013] Finally, it should be noted that, particularly in the case of top-quality watch movements, the use of adhesives or synthetic products that are incompatible with the high level of processing and expertise required for such watch movements should be avoided as much as possible.

[0014] European patent application EP1515200A1 discloses a hairspring for a hairspring balance assembly of a mechanical watch movement, the free end of the outermost circle of the hairspring comprising an opening capable of elastic deformation in order to receive and clamp a hairspring stud-type attachment element. Preferably, the attachment element is cylindrical with a circular cross-section and comprises a flat area, and the free end of the outermost circle of the hairspring contacts the flat area to prevent the free end from rotating around the attachment element during the operation of the movement. The attachment element allows the free end of the outermost circle of the hairspring to be attached without the need for auxiliary attachment means such as pins or adhesives. In addition, by adjusting the position of the free end of the outermost circle of the hairspring relative to the attachment element, the height of the free end on the attachment element can be adjusted. This is achieved by frictional engagement of the free end of the outermost circle of the hairspring with the attachment element. However, this is problematic because there is a risk that, for example in the event of an impact, the free end of the outermost coil will change position relative to its attachment element or even become detached from this attachment element, which would in the best case alter the timekeeping accuracy of the balance-with-sprung assembly and in the worst case lead to a malfunction of the timepiece. It should also be noted that, since the attachment of the outermost coil of the hairspring is ensured by friction forces generated by the elastic contact between the opening provided in the free end of the outermost coil of the hairspring and the attachment element, this does not guarantee real durability of the hairspring, since these friction forces will tend to weaken over time and through wear, so that the friction forces between the edge of the opening of the free end of the outermost coil of the hairspring and the attachment element quickly become insufficient to ensure that the hairspring is fixed to this attachment element. Summary of the invention

[0015] The object of the present invention is to solve the above-mentioned and other problems by providing a mechanical assembly which allows the hairspring of a timepiece movement to be securely attached without elastic deformation of the outermost coil and without the use of adhesives, making it possible to disassemble and reassemble the hairspring when necessary without causing damage.

[0016] To this end, the present invention relates to an attachment assembly for detachably attaching a hairspring of a watch movement, the watch movement comprising a balance bridge, the attachment assembly comprising the hairspring on the one hand, and a retaining structure for the hairspring and a detachable locking component on the other hand, the hairspring comprising a coil winding extending between a first free end of a first inner coil and a second free end of an outermost coil, the second free end of the outermost coil of the hairspring comprising an attachment structure, the retaining structure being engaged in the attachment structure to ensure that the hairspring is detachably attached via its outermost coil, the size of the attachment structure being designed so that, in its natural rest position, the hairspring does not contact the retaining structure engaged in the attachment structure, the detachable locking component for ensuring the second free end of the outermost coil of the hairspring is detachably attached is mounted on the retaining structure to lock the attachment structure.

[0017] In a particular embodiment of the invention, said attachment structure is an opening formed in the second free end of the outermost coil of said balance spring.

[0018] In a particular embodiment of the invention, the second free end of the outermost turn of the balance spring in which the opening is formed is made integral with the assembly of the balance spring.

[0019] In another particular embodiment of the invention, said opening is formed by a curved portion of the second free end of the outermost coil of said balance spring.

[0020] In yet another particular embodiment of the invention, the second free end of the outermost coil of the balance spring is provided with a plate in which the opening is formed.

[0021] In yet another particular embodiment of the invention, said plate is fixed to the second free end of the outermost coil of said balance spring.

[0022] In yet another particular embodiment of the invention, said plate is attached to the second free end of the outermost coil of said balance spring by welding.

[0023] In yet another embodiment of the present invention, the opening is elongated in shape.

[0024] In yet another embodiment of the present invention, the major axis of the elongated shaped opening is located in the continuation of the outermost circle.

[0025] In yet another particular embodiment of the invention, said stud is arranged to engage in an opening formed in the second free end of the outermost coil of said balance spring.

[0026] In yet another particular embodiment of the invention, the support is made in one piece with the balance bridge of the timepiece movement.

[0027] In yet another specific embodiment of the present invention, the retaining structure comprises a supporting member, the supporting member is formed by a pile, and the support column is mounted on top of the pile.

[0028] In yet another particular embodiment of the invention, the support member is arranged in a recess formed in the balance cock.

[0029] In yet another particular embodiment of the invention, the support member is arranged in the recess by friction fit.

[0030] In yet another particular embodiment of the present invention, the support member is threaded in the recess.

[0031] In yet another specific embodiment of the present invention, in order to prevent the support member from being unscrewed at an inopportune time, a retaining member is provided between the balance cock and the support member.

[0032] In yet another specific embodiment of the present invention, the retaining member is a spring washer.

[0033] In yet another embodiment of the present invention, the detachable locking member is a washer detachably attached to the support column.

[0034] In yet another embodiment of the invention, said gasket is pressed onto said support column.

[0035] In yet another embodiment of the invention, the retaining structure comprises a support member arranged in a recess formed in the balance cock and covered by a locking member, the locking member being provided with a support column received in an opening formed in the support member.

[0036] In yet another particular embodiment of the invention, a flexible element for varying the stiffness of the balance spring is provided between the second free end of the outermost turn of the balance spring and a lever surrounding the coil winding, the lever terminating in a plate in which the opening is formed.

[0037] The invention also relates to a method for adjusting the deflection of a balance-with-sponge assembly attached by means of an attachment assembly according to the invention, wherein the attachment structure comprised by the second free end of the outermost winding of the balance spring is engaged on a pillar of a support part, the support part is pivoted, if necessary, in one direction or the other, until the pillar is no longer in contact with the attachment structure of the balance spring, whereby the deflection of the balance-with-sponge assembly is adjusted by pivoting the balance-with-sponge assembly about the balance axle until the impulse stud of the balance disc is aligned with the escapement wire passing through the balance axle and the pallet fork axle, and then, once the deflection of the balance-with-sponge assembly has been adjusted, it is ensured that the pillar of the support part is no longer in contact with the attachment structure of the balance spring, and if so, the support part is rotated again so as to move the pillar away from the attachment structure of the balance spring, and the detachable locking part is then attached to the pillar in order to lock the second free end of the outermost winding of the balance spring.

[0038] The present invention also relates to a method for adjusting the running time of a balance assembly with hairspring, wherein the hairspring of the balance assembly is attached by means of an attachment assembly according to the present invention, wherein, after pressing the detachable locking part onto the pillar to lock the second free end of the outermost winding of the hairspring, the support part is pivoted clockwise or counterclockwise to drive the second free end of the outermost winding of the hairspring.

[0039] Thanks to these characteristics, the invention provides an assembly that allows the hairspring of a timepiece movement to be attached in a removable, repositionable manner, without the aid of adhesives, thereby ensuring that the free end of the outermost coil of the hairspring is immobilized without inducing mechanical stresses in the hairspring, in particular in the plane in which the windings of its coils extend, thereby affecting the regularity of the timepiece movement. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0041] - Figure 1 is an overall perspective view of a simplified embodiment of an attachment assembly for removably attaching a balance spring of a timepiece movement;

[0042] - Figure 2 is an overall perspective view of a modified embodiment of an attachment assembly for detachably attaching a hairspring of a timepiece movement;

[0043] - Figure 3 It includes Figure 2 A top view of a silicon balance spring of a first flexible arm and a second flexible arm in an attachment assembly;

[0044] - Figure 4 is a perspective view of a balance spring, the outermost convolution of which is provided with an integral plate, in which openings are formed for receiving the stays;

[0045] - Figure 5 is a perspective view of a balance spring equipped with a plate attached to the free end of the outermost turn of the balance spring, the plate having openings formed therein for receiving the posts;

[0046] - Figure 6 is a perspective view of the balance spring, the outermost turn of which is bent to form an opening for receiving the post;

[0047] - Figure 7 1 is a schematic diagram showing an example in which a support column is integrated with a balance bridge of a watch movement.

[0048] - Figure 8 is a schematic diagram showing an example in which the retaining structure comprises a support member formed by a pile member having a support column mounted on top and arranged in a recess formed in the balance cock by friction fit;

[0049] - Fig. 9 An example is shown in which the retaining structure comprises a bearing member formed by a pile with a support on top and arranged in a recess formed in the balance cock by means of a screw connection, with a washer interposed between the balance cock and the bearing member to prevent any untimely unscrewing;

[0050] - Fig.10 is a perspective view of the balance spring, the outermost turn of which is bent to form a hook to receive the post;

[0051] - Fig.11 and 12 The arrangement of the retaining structure in the form of a support member arranged in a recess formed in the balance cock, the outermost turn of the balance spring being covered by a locking member provided with a support received in an opening formed in the support member, is shown in the assembled and disassembled states respectively. DETAILED DESCRIPTION

[0052] The present invention derives from the general inventive concept of providing a mechanical assembly that allows the second free end of the outermost turn of a hairspring of a balance-with-sprung assembly of a timepiece movement to be attached without the use of adhesives. By dispensing 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; more specifically, in particular in the high-end watch sector, it is obvious that it will be avoided as much as possible to have to resort to the use of adhesives to assemble mechanical parts. According to another of its advantages, the mechanical assembly according to the invention allows the second free end of the outermost turn of the hairspring to be attached in a detachable manner, so that the positioning of the hairspring can be readjusted, if necessary, when the timepiece returns to the factory. Another advantage of the mechanical assembly according to the invention is that it allows the second free end of the outermost turn of a hairspring of a timepiece movement to be attached without inducing mechanical stresses in this second end, in particular in the plane in which the windings forming the hairspring extend, which is very advantageous for the timekeeping accuracy of the balance-with-sprung assembly.

[0053] The attachment assembly according to the invention, indicated as a whole by the general reference 1 , serves to removably attach a balance spring 2 of a timepiece movement comprising a balance cock 4 .

[0054] More specifically, if Figure 1 As shown, the attachment assembly 1 comprises, in addition to the balance spring 2 , a retaining structure 8 and a detachable locking member 10 .

[0055] from Figure 1As can be seen in the figure, the hairspring 2 comprises a coil winding 12 extending between a first free end 14 of a first inner coil 16 and a second free end 18 of an outermost coil 20. According to the invention, the second free end 18 of the outermost coil 20 of the hairspring 2 comprises an attachment structure which, in a preferred and non-limiting embodiment of the invention, is in the form of an opening 22 in which a retaining structure 8 engages to ensure the detachable attachment of the hairspring 2 by its outermost coil 20. The dimensions of the opening 22 are designed so that, in the natural rest position of the hairspring 2, the edge 24 of this opening 22 does not come into contact with the retaining structure 8 engaged in this opening 22. Therefore, attaching the hairspring 2 by means of the attachment assembly 1 according to the invention does not induce any stress in this hairspring 2 in the XY plane in which the hairspring 2 extends, and therefore does not have an impact on the timekeeping accuracy. A detachable locking part 10 is used to ensure the detachable attachment of the second free end 18 of the outermost coil 20 of the hairspring 2, which locking part 10 preferably follows the engagement of the hairspring 2 on the retaining structure 8 by pressing in.

[0056] According to a particular embodiment of the invention, the opening 22 provided in the second free end 18 of the outermost coil 20 of the balance spring 2 is preferably, but not exclusively, elongated in shape, with its major axis 26 extending in the continuation of the outermost coil 20 (see Figure 3 ).

[0057] exist Figures 4 to 6 In the embodiment shown, the opening 22 is elongated in shape, with a radius of curvature R centered on the center 27 of the coil winding 12 .

[0058] The opening 22 can be realized in different ways.

[0059] In one embodiment of the invention, the second free end 18 of the outermost coil 20 of the balance spring 2 in which the opening 22 is formed is made integrally with the balance spring 2 assembly. Thus, the outermost coil 20 of the balance spring 2 may be provided with an integrally made plate 28 in which the opening 22 is formed ( Figure 4 ). In contrast, the plate 28 may be connected by a connection process such as welding ( Figure 5 ) is attached to the second free end 18 of the outermost coil 20 of the hairspring 2. The opening 22 ( Figure 6 ).

[0060] Retaining structure 8 comprises a stud 32 arranged to engage in an opening 22 formed in second free end 18 of outermost coil 20 of balance spring 2 .

[0061] In the first embodiment, the support 32 is made integrally with the balance bridge 4 of the watch movement ( Figure 7 ).

[0062] According to another embodiment of the invention, the retaining structure 8 comprises a support part 34 formed by a pile 36 on top of which a support 32 is mounted. This support part 34 is arranged in a recess 38 formed in the balance cock 4. The support part 34 is formed by a friction fit ( Figure 8 ) or by threaded connection ( Fig. 9 ) is positioned in the recess 38. If the support member 34 is screwed into the recess 38, the support member 34 has an external thread and the recess 38 is provided with a complementary thread on the inner side wall 40. In order to prevent the support member 34 from being accidentally unscrewed, a retaining member 42 (such as a spring washer) may be arranged between the swing cock 4 and the support member 34. Fig. 9 ).

[0063] The removable locking member 10 is a washer that is removably attached to the support post 32, typically by press-fitting.

[0064] In its simplified embodiment, the attachment assembly 1 according to the invention allows the adjustment of the runout of the balance-with-sponge assembly 44. Moreover, in its preferred embodiment, the attachment assembly 1 according to the invention allows not only the adjustment of the runout of the balance-with-sponge assembly 44, but also the adjustment of the travel time of such a balance-with-sponge assembly 44.

[0065] As described above, the attachment assembly 1 according to the invention is first mounted by engaging the opening 22 provided in the second free end 18 of the outermost turn 20 of the balance spring 2 on the stud 32 of the support part 34. Typically, the dimensions of the entire mechanical assembly formed by the balance spring 2, the sprung balance assembly 44 equipped with such a balance spring 2 and the retaining structure 8 are designed so that, when the stud 32 of the support part 34 is engaged in the opening 22 of the balance spring 2, the edge 24 of the opening 22 of the balance spring 2 is not in contact with the stud 32 engaged in this opening 22. However, in the rare case where 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 stud 32 is no longer in contact with the edge 24 of the opening 22 of the balance spring 2. Thereafter, the deflection of the sprung balance assembly 44 is adjusted by rotating it about the balance staff 46 until the impulse stud 48 of the balance disc 50 is aligned with the escapement wire passing through the balance staff 46 and the pallet fork axle (not shown in the figure). Once the deflection of the balance assembly 44 has been adjusted, it is once again ensured that the pillars 32 of the support part 34 are not in contact with the edge 24 of the opening 22 of the balance spring 2; as before, in the rare case that this is not the case, the invention makes it possible to rotate the support part 34 again, so as to move the pillars 32 away from the edge 24 of the opening 22 of the balance spring 2, and then to press the washers onto the pillars 32 in order to lock the second free end 18 of the outermost turn 20 of the balance spring 2. Conversely, that is, if no contact is observed between the edge 24 of the opening 22 of the balance spring 2 and the pillars 32 of the support part 34, the balance spring 2 can be locked directly by attaching the washers to the pillars 32.

[0066] Of course, it is understood that if the support member 34 is made integrally with the balance cock 4 , the support member 34 cannot pivot.

[0067] exist Figure 2 In the preferred embodiment of the present invention shown in perspective in FIG. 4 , it is possible to adjust not only the deflection of the balance assembly 44 but also the running error of the balance assembly 44. The operation of adjusting the running error of the balance assembly 44 occurs after the second free end 18 of the outermost coil 20 of the hairspring 2 has been locked by attaching the washer to the pillar 32. At this time, the support part 34 pivots clockwise or counterclockwise, thereby driving the second free end 18 of the outermost coil 20 of the hairspring 2.

[0068] More specifically, Figure 3The balance spring 2 is shown to include a flexible element 52 consisting of a pivot 54 and a rigid part 60, the pivot 54 including a first flexible blade 56 and a second flexible blade 58 that do not cross. The first flexible blade 56 and the second flexible blade 58 are connected on the one hand to an elongated fixed support 62 in the transverse direction and on the other hand to the pivot 54 by being moved toward each other. Thus, the first flexible blade 56 and the second flexible blade 58 move toward each other from the fixed support 62 to the pivot 54. The fixed support 62 is attached to an attachment part 62a that is integral with the balance cock 4. The second free end 18 of the outermost ring 20 of the balance spring 2 is connected to the pivot 54. In the figure, a variable torque is applied to the additional blade connecting the outermost ring 20 to the rigid part 60, so that the stiffness of the additional blade is changed and thus the stiffness of the balance spring 2 is changed, thereby changing the time difference of the balance assembly 44 with the hairspring. To this end, the balance spring 2 is extended beyond its flexible element 52 by means of a lever 64 which passes around the coil winding 12 and ends in a plate 28 in which an opening 22 according to the invention is provided. 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 the European patent application EP21202213.1 filed by the applicant.

[0069] It goes without saying that the invention is not limited to the embodiments that have just been described and that a person skilled in the art may envisage various simple modifications and alternative embodiments without departing from the scope of the invention as defined by the appended claims.

[0070] The support 32 can be made in one piece with the balance cock 4. If the support part 34 is a separate part and is mounted by press-fitting in a recess 38 machined in the balance cock 4, the support part 34 can pivot in both clockwise and counterclockwise directions. When the support part 34 pivots, the support 32 also pivots, so that it does not come into contact with the edge 24 of the contour of the opening 22 formed in the free end 18 of the outermost coil 20 of the balance spring 2. Therefore, the balance spring 2 can be placed spontaneously in its natural rest position, without being affected by any mechanical stress, which is the most favorable solution for the timekeeping accuracy of the balance assembly 44 with hairspring.

[0071] In general, the manufacturing tolerances of balance spring 2 (especially when it is made of silicon) are very strict, so the position of the geometric center of opening 22 formed in free end 18 of outermost coil 20 of balance spring 2 is known in advance very accurately, which makes it possible to accurately position support 32 on balance cock 4, or to position support part 34 corresponding to the assembly formed by stud 36 and support 32 in recess 38 provided for this purpose in balance cock 4.

[0072] If the balance spring 2 is made of silicon, the free end 18 of the outermost coil 20 of the balance spring 2, in which the opening 22 is formed, is made integral with the assembly of the balance spring 2. If the balance spring 2 is made of a metal alloy, the opening 22 for receiving the post 32 of the support member 34 can be formed by simply bending the free end 18 of the outermost coil 20 of the balance spring 2. A plate 28 in which the opening 22 for receiving the post 32 of the support member 34 is also attached to the free end 18 of the outermost coil 20 of the balance spring 2, typically by welding.

[0073] In the rare case that, after the installation of the balance spring 2 and the engagement of the support 32 in the opening 22 provided in the free end 18 of the outermost coil 20 of the balance spring 2, the edge 24 of this opening 22 is observed to come into mechanical contact with the support 32 at any point, the invention advantageously allows the support member 34 to be pivoted until no mechanical contact is observed. Thus, in any case, the invention ensures that the free end 18 of the outermost coil 20 of the balance spring 2 is immobilized without inducing any stress in the XY plane in which the balance spring 2 extends, which is very beneficial to the timekeeping accuracy of the balance assembly 44 with hairspring.

[0074] In a simplified alternative embodiment of the invention, free end 18 of outermost coil 20 of balance spring 2 has only one attachment point, namely post 32 of support member 34, which engages in opening 22 formed in free end 18 of outermost coil 20 of balance spring 2, and acts as a balance spring stud, so that only the deflection of balance-with-sprung assembly 44 can be adjusted.

[0075] 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 deflection and the running error of the hairspring balance assembly 44 can be adjusted. In addition, it is understood that, thanks to the invention, the running error of the hairspring balance assembly 44 can be fine-tuned in different ways: for example, by adding or removing material to change the inertia of the balance wheel, or by tightening or loosening the counterweight. According to the invention, the running error of the hairspring balance assembly 44 can also be adjusted by changing the stiffness of the hairspring 2. Some hairspring balance assemblies can even be adjusted in two ways at the same time.

[0076] The stud 36 of the bearing part 34 may be threaded to allow fine adjustment of the height along an axis Z perpendicular to the bearing surface provided by the bearing part 34. In order to prevent the threaded bearing part 34 from being accidentally unscrewed, a retaining member 42, for example of the spring washer type, may be arranged between the threaded bearing part 34 and the surface of the balance cock 4 so as to lock the threaded stud 36. Thanks to the invention, the run-time error of the sprung balance assembly 44 can be adjusted by varying the stiffness of the hairspring 2 attached to the balance staff 46 by means of the collet 66, which is much simpler than adjusting the run-time error of the sprung balance assembly by varying the inertia of the balance wheel (for example by adding or removing material, or by moving weights or screws, etc.).

[0077] according to Fig.10 In the particular embodiment of the invention shown, the attachment structure may have an open geometry, for example shaped like a hook 68, in which a retaining structure 8 is engaged to ensure the removable attachment of the balance spring 2 by its outermost coil 20. This retaining structure 8 is of the stud 32 type, arranged in the internal space delimited by the hook 68 and held in place by the retaining member 42. Normally, when the balance spring 2 is assembled, there should be no mechanical contact between the hook 68 and the stud 32. However, if this is not the case, the bearing member 34 can be rotated until no mechanical contact is observed.

[0078] According to a particular embodiment of the invention, retaining structure 8 comprises a support member 70 arranged in a recess 72 formed in balance cock 4. Support member 70 is arranged in recess 72 by friction fit or by a screw connection. Free end 18 of outermost coil 20 of balance spring 2 rests on this support member 70 and is covered by a locking member 74, the lower side of which is provided with a support 76 received in an opening 78 formed in support member 70.

[0079] Reference numerals list

[0080] 1. Attach components

[0081] 2. Balance Spring

[0082] 4. Swing splint

[0083] 8. Maintain structure

[0084] 10. Removable locking parts

[0085] 12. Coil Winding

[0086] 14. First free end

[0087] 16. First inner circle

[0088] 18. Second free end

[0089] 20. Outermost circle

[0090] 22. Open your mouth

[0091] 24. Edge

[0092] 26. Long axis

[0093] 27. Center

[0094] 28. Board

[0095] 30.Bend

[0096] 32. Pillar

[0097] 34. Supporting parts

[0098] 36. Piles

[0099] 38. Concave

[0100] 40.Inner wall

[0101] 42. Keep the parts

[0102] 44. Balance wheel assembly

[0103] 46. ​​Swing axis

[0104] 48. Impact nail

[0105] 50. Balance wheel disc

[0106] 52. Flexible components

[0107] 54. Pivot

[0108] 56.First flexible blade

[0109] 58. Second flexible blade

[0110] 60. Rigidity

[0111] 62.Fixed support

[0112] 62a. Attachment parts

[0113] 63.Additional blades

[0114] 64. Leverage

[0115] 66. Inner pile

[0116] 68.Hook

[0117] 70.Supporting parts

[0118] 72 concavity

[0119] 74. Locking parts

[0120] 76. Pillar

[0121] 78. Open your mouth

Claims

1. An attachment assembly (1) for detachably attaching a hairspring (2) of a watch movement, the watch movement comprising a balance bridge (4), the attachment assembly comprising the hairspring (2) on the one hand, and a retaining structure (8) for the hairspring (2) and a detachable locking part (10) on the other hand, the hairspring (2) comprising a coil winding (12), the coil winding (12) extending between a first free end (14) of a first inner turn (16) and a second free end (18) of an outermost turn (20), the outermost turn (20) of the hairspring (2) having a first free end (14) and a second free end (18) of the outermost turn (20) of the hairspring (2) being arranged on the first free end (14) of the hairspring (2) and a second free end (18) of the outermost turn (20) of the hairspring (2) being arranged on the second free end (18) of the hairspring (2) The two free ends (18) include an attachment structure, the retaining structure (8) is engaged in the attachment structure to ensure that the hairspring (2) is detachably attached through its outermost coil (20), the size of the attachment structure is designed so that, in the natural rest position of the attachment structure, the attachment structure does not contact the retaining structure (8) engaged in the attachment structure, and the detachable locking component (10) for detachably attaching the second free end (18) of the outermost coil of the hairspring (2) is installed on the retaining structure (8) to lock the attachment structure.

2. The attachment assembly (1) for detachably attaching a hairspring (2) of a timepiece movement according to claim 1, characterized in that: The attachment structure is an opening (22) provided in the second free end (18) of the outermost coil (20) of the balance spring (2).

3. The attachment assembly (1) for detachably attaching a hairspring (2) of a timepiece movement according to claim 2, characterized in that: The opening (22) is elongated in shape and has a major axis (26) located in the continuation of the outermost ring (20).

4. The attachment assembly (1) for detachably attaching a hairspring (2) of a timepiece movement according to claim 1, characterized in that: The second free end (18) of the outermost coil (20) of the hairspring (2) in which the opening (22) is formed is made integrally with the assembly of the hairspring (2).

5. The attachment assembly (1) for detachably attaching a hairspring (2) of a timepiece movement according to claim 1, characterized in that: The opening (22) is formed by a bent portion (30) of the second free end (18) of the outermost coil (20) of the balance spring (2).

6. The attachment assembly (1) for detachably attaching a hairspring (2) of a timepiece movement according to claim 1, characterized in that: The second free end (18) of the outermost coil (20) of the balance spring (2) is provided with a plate (28) in which the opening (22) is formed.

7. An attachment assembly (1) for detachably attaching a balance spring (2) of a timepiece movement according to claim 6, characterized in that: The plate (28) is fixed to the second free end (18) of the outermost coil (20) of the balance spring (2).

8. An attachment assembly (1) for detachably attaching a balance spring (2) of a timepiece movement according to claim 7, characterized in that: The plate (28) is attached to the second free end (18) of the outermost coil (20) of the balance spring (2) by welding.

9. An attachment assembly (1) for detachably attaching a balance spring (2) of a timepiece movement according to any one of claims 1 to 8, characterized in that: The retaining structure (8) comprises a post (32; 76) arranged to engage in an opening (22) formed in the second free end (18) of the outermost coil (20) of the balance spring (2).

10. An attachment assembly (1) for detachably attaching a balance spring (2) of a timepiece movement according to claim 9, characterized in that: The support column (32) is made into one piece with the swing plate (4) of the watch movement.

11. The attachment assembly (1) for detachably attaching a balance spring (2) of a timepiece movement according to claim 9, characterized in that: The retaining structure (8) comprises a supporting part (34), the supporting part (34) being formed by a pile (36), the pillar being mounted on top of the pile (36).

12. An attachment assembly (1) for detachably attaching a balance spring (2) of a timepiece movement according to claim 11, characterized in that: The support member (34) is disposed in a recess (38) formed in the balance cock (4).

13. An attachment assembly (1) for detachably attaching a balance spring (2) of a timepiece movement according to claim 12, characterized in that: The bearing member (34) is arranged in the recess (38) by means of a friction fit.

14. The attachment assembly (1) for detachably attaching a balance spring (2) of a timepiece movement according to claim 12, characterized in that: The support member (34) is screwed into the recess (38).

15. An attachment assembly (1) for detachably attaching a balance spring (2) of a timepiece movement according to claim 14, characterized in that: In order to prevent the support component (34) from being unscrewed at an inappropriate time, a retaining component (42) is arranged between the swing plate (4) and the support component (34).

16. An attachment assembly (1) for detachably attaching a balance spring (2) of a timepiece movement according to claim 15, characterized in that: The retaining member (42) is a spring washer.

17. An attachment assembly (1) for detachably attaching a balance spring (2) of a timepiece movement according to any one of claims 9 to 16, characterized in that: The removable locking member (10) is a washer removably attached to the support column (32).

18. An attachment assembly (1) for detachably attaching a balance spring (2) of a timepiece movement according to claim 17, characterized in that: The washer is press-fitted onto the support post (32).

19. The attachment assembly (1) for detachably attaching a balance spring (2) of a timepiece movement according to claim 9, characterized in that: The retaining structure (8) comprises a support part (70) which is arranged in a recess (72) formed in the swing plate (4) and is covered by a locking part (74), wherein the locking part (74) is provided with the support (76) which is received in an opening (78) formed in the support part (70).

20. An attachment assembly (1) for detachably attaching a balance spring (2) of a timepiece movement according to any one of claims 1 to 19, characterized in that: A flexible element (52) for changing the stiffness of the balance spring (2) is provided between the second free end of the outermost turn of the balance spring and a lever (64) surrounding the coil winding (12), the opening (22) being provided in the free end of the lever.

21. A method for adjusting the deflection of a balance-with-sponge assembly, the balance-with-sponge assembly comprising a balance spring (2) attached by means of an attachment assembly according to any one of claims 1 to 9 and 11 to 20, wherein: Engaging the attachment structure included in the second free end (18) of the outermost coil (20) of the balance spring (2) on the pillar (32) of the support part (34), pivoting the support part (34) in one direction or the other, if necessary, until the pillar (32) is no longer in contact with the attachment structure of the balance spring (2), and then adjusting the balance spring (44) by pivoting the balance spring assembly (44) about the balance axle (46) until the impulse stud (48) of the balance disc (50) is aligned with the escapement wire passing through the balance axle and the escapement fork axle The deflection of the balance assembly (44) with hairspring is adjusted, and then, once the deflection of the balance assembly (44) with hairspring is adjusted, it is ensured that the pillar (32) of the support member (34) is no longer in contact with the attachment structure of the hairspring (2). If so, the support member (34) is rotated again to move the pillar (32) away from the attachment structure of the hairspring (2), and then the detachable locking member (10) is pressed onto the pillar (32) to lock the second free end (18) of the outermost coil (20) of the hairspring (2).

22. A method for adjusting the run-time of a balance assembly (44) having a hairspring attached by means of an attachment assembly according to any one of claims 1 to 20, wherein: After the detachable locking member (10) is pressed onto the pillar (32) to lock the second free end (18) of the outermost coil (20) of the hairspring (2), the support member (34) is pivoted clockwise or counterclockwise to drive the second free end (18) of the outermost coil (20) of the hairspring (2).

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