Attachment assembly for detachably attaching hairspring of timepiece movement

Abstract

The utility model relates to an attachment assembly (1) for detachably attaching a hairspring (2) of a clock movement comprising a balance plate (4), the attachment assembly comprises the hairspring (2), a retaining structure (8) for the hairspring (2) and a detachable locking part (10), the hairspring (2) comprises 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), 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 utility model relates to an attachment component for attaching a hairspring of a watch movement. 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] Therefore, the hairspring will alternately expand and contract: this is known as breathing. However, during expansion and contraction, many factors prevent the hairspring from expanding synchronously. In particular, the hairspring is necessarily subject to oxidation and magnetism, which can cause the coils to stick together and disrupt the accuracy of the watch, or even cause it to stop completely. On the other hand, the effect of atmospheric stress is minimal. For a long time, temperature has been the main problem, as heat causes metals to expand and cold causes them to contract. Therefore, the hairspring must be elastic so that it can deform but always return to its original shape.

[0007] The material used to manufacture the hairspring is usually steel. The steel used is ductile and must be corrosion-resistant. Developments in the past two decades have also proposed using silicon to make hairsprings. Silicon hairsprings have higher timekeeping accuracy than steel hairsprings, especially because they are insensitive to magnetism. However, they are more expensive and are also more difficult to assemble due to their fragility.

[0008] The hairspring must be isochronous. No matter how far the balance wheel rotates, it must always take the same amount of time to oscillate. If the hairspring only contracts by a few degrees, it will accumulate little energy and return to its equilibrium position slowly. If the hairspring is far from its equilibrium position, it will move very quickly in the opposite direction. Importantly, these two strokes need to 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 whether the watch is fully wound or in the last few 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 impact on the timekeeping accuracy of the watch movement. In most mechanical watch movements, the two ends of the hairspring are inserted into parts with holes and fixed with pins, and then the pins are manually forced to assemble with pliers. This causes the hairspring to rotate slightly, thus damaging the timekeeping accuracy of the movement.

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

[0011] To solve these problems, the applicant has proposed a method for attaching a hairspring, which includes bonding the outermost turn of the hairspring inside an outer stud by means of a drop of polymerizable liquid adhesive, for example by means of ultraviolet radiation. Thus, even when depositing a drop of adhesive, for example by means of a syringe-type adhesive dispenser, the free end of the last turn of the hairspring moves slightly under the weight of the drop of adhesive, thereby causing an unwanted mechanical stress in the hairspring. However, the adhesive has sufficient fluidity before hardening to allow the free end of the last turn of the hairspring to spontaneously return to its rest position. Therefore, the mechanical stress caused in the hairspring during the deposition of the liquid adhesive drop disappears by itself, and the timekeeping consistency of the hairspring is not affected by the bonding operation performed thereon.

[0012] Therefore, the above solution allows the hairspring to be attached inside the outer stud through the free end of its outermost turn, while eliminating all or at least most of the mechanical stresses that are usually caused in such a hairspring during the assembly of the hairspring. This greatly improves the timekeeping consistency of the hairspring. However, during use, the applicant still realizes that the hardened adhesive mass formed when the drop of liquid adhesive used to attach the free end of the outermost turn of the hairspring polymerizes sometimes detaches from the outer stud, which of course causes the immediate failure of the timepiece movement equipped with this hairspring. This situation is especially due to problems with the surface condition of the outer stud, which prevent the adhesive mass from adhering well to the outer stud, as well as due to the creep and aging of the adhesive mass over time. In addition, when the ambient temperature rises, most adhesives soften, thereby changing the effective length of the hairspring and thus the stiffness of the hairspring, and therefore having a negative impact on the timekeeping of the timepiece movement.

[0013] Finally, it should be noted that especially in the case of top-of-the-line timepiece movements, it is desirable to avoid, as much as possible, the use of adhesives or synthetic products that are difficult to be compatible with the high levels of machining and expertise required for such timepiece movements.

[0014] European patent application EP1515200A1 discloses a hairspring for a hairspring balance wheel assembly of a mechanical watch movement. The free end of the outermost coil of the hairspring includes an opening that can elastically deform to receive and clamp a hairspring outer stud type attachment element. Preferably, the attachment element is cylindrical with a circular cross-section and includes a flat area, and the free end of the outermost coil 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 coil 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 coil 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 frictionally engaging the free end of the outermost coil of the hairspring with the attachment element. However, this has problems because there is a risk that, for example, in the event of an impact, the free end of the outermost coil will change its position relative to its attachment element or even become detached from the attachment element, which will change the timekeeping accuracy of the hairspring balance wheel assembly in the best case and cause a watch failure in the worst case. It should also be noted that since the attachment of the outermost coil of the hairspring is ensured by the frictional force 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 the true durability of the hairspring because over time and with wear, these frictional forces will tend to weaken, making the frictional force between the opening edge 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 the attachment element. SUMMARY OF THE UTILITY MODEL

[0015] The object of the present utility model is to solve the above and other problems by providing a mechanical assembly that allows the hairspring of a watch movement to be firmly attached without the need for elastic deformation of the outermost coil or the use of adhesives, so that the hairspring can be disassembled and reassembled when necessary without causing damage.

[0016] To this end, the present utility model relates to an attachment assembly for detachably attaching a hairspring of a watch movement, the watch movement including a balance bridge plate. The attachment assembly includes, on the one hand, the hairspring and, on the other hand, a holding structure for the hairspring and a detachable locking member. The hairspring includes a coil winding that extends 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 includes an attachment structure, and the holding structure engages in the attachment structure to ensure that the hairspring is detachably attached through its outermost coil. The size of the attachment structure is designed such that, in its natural rest position, the hairspring does not contact the holding structure engaged in the attachment structure. The detachable locking member for ensuring the detachable attachment of the second free end of the outermost coil of the hairspring is mounted on the holding structure to lock the attachment structure.

[0017] In a specific embodiment of the present utility model, the attachment structure is an opening formed in the second free end of the outermost circle of the hairspring.

[0018] In a specific embodiment of the present utility model, the second free end of the outermost circle of the hairspring in which the opening is formed is integrally formed with the hairspring.

[0019] In another specific embodiment of the present utility model, the opening is formed by a bent portion of the second free end of the outermost circle of the hairspring.

[0020] In yet another specific embodiment of the present utility model, a plate is provided at the second free end of the outermost circle of the hairspring, and the opening is formed in the plate.

[0021] In yet another specific embodiment of the present utility model, the plate is fixed to the second free end of the outermost circle of the hairspring.

[0022] In yet another specific embodiment of the present utility model, the plate is attached to the second free end of the outermost circle of the hairspring by welding.

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

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

[0025] In yet another specific embodiment of the present utility model, the strut is arranged to engage within an opening formed in the second free end of the outermost circle of the hairspring.

[0026] In yet another specific embodiment of the present utility model, the strut is integrally formed with the balance staff plate of the timepiece movement.

[0027] In yet another specific embodiment of the present utility model, the holding structure includes a supporting member formed by a stud, and the strut is mounted on the top of the stud.

[0028] In yet another specific embodiment of the present utility model, the supporting member is disposed within a recess formed in the balance staff plate.

[0029] In yet another specific embodiment of the present utility model, the supporting member is arranged in the recess by a friction fit.

[0030] In yet another specific embodiment of the present utility model, the supporting member is threadedly connected in the recess.

[0031] In yet another specific embodiment of the present utility model, in order to prevent the untimely loosening of the support member, a retaining member is provided between the balance bridge plate and the support member.

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

[0033] In yet another embodiment of the present utility model, the detachable locking member is a washer detachably attached to the strut.

[0034] In yet another embodiment of the present utility model, the washer is press-fitted onto the strut.

[0035] In yet another embodiment of the present utility model, the retaining structure includes a support member disposed within a recess formed in the balance bridge plate and covered by a locking member, the locking member being provided with a strut received within an opening formed in the support member.

[0036] In yet another specific embodiment of the present utility model, a flexible element for changing the stiffness of the hairspring is provided between the second free end of the outermost coil of the hairspring and a lever surrounding the coil winding, the lever terminating at a plate in which the opening is formed.

[0037] The present disclosure also relates to a method for adjusting the runout of a hairspring balance wheel assembly attached by means of an attachment assembly according to the present utility model, wherein the attachment structure included in the second free end of the outermost coil of the hairspring is engaged with the strut of the support member, and if necessary, the support member is pivoted in one direction or the other until the strut is no longer in contact with the attachment structure of the hairspring, and then the runout of the hairspring balance wheel assembly is adjusted by pivoting the hairspring balance wheel assembly about the balance axis until the impact pin of the balance disk is aligned with the escapement line passing through the balance axis and the escapement fork axis, and then, once the runout of the hairspring balance wheel assembly has been adjusted, it is ensured that the strut of the support member is no longer in contact with the attachment structure of the hairspring, and if in contact, the support member is rotated again to move the strut away from the attachment structure of the hairspring, and then the detachable locking member is attached to the strut to lock the second free end of the outermost coil of the hairspring.

[0038] The present disclosure also relates to a method for adjusting the time difference of a hairspring balance wheel assembly, wherein the hairspring of the hairspring balance wheel assembly is attached by means of an attachment assembly according to the present utility model, and wherein, after the detachable locking member is press-fitted onto the strut to lock the second free end of the outermost coil of the hairspring, the support member is pivoted clockwise or counterclockwise, thereby driving the second free end of the outermost coil of the hairspring.

[0039] Due to these features, the present utility model provides a component that allows the hairspring of a timepiece movement to be attached in a detachable and repositionable manner without the aid of an adhesive, thereby ensuring that the free end of the outermost coil of the hairspring remains fixed without inducing mechanical stress in the hairspring, particularly in the plane in which the coil windings of the hairspring extend, and thus not affecting the regularity of the timekeeping of the timepiece movement. Description of the Drawings

[0040] The other features and advantages of the present utility model will become more apparent from the following detailed description of an embodiment with reference to the accompanying drawings, which is 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 detachably attaching the hairspring of a timepiece movement;

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

[0043] - Figure 3 is a top view of a silicon hairspring including a first flexible arm and a second flexible arm in the attachment assembly for Figure 2 ;

[0044] - Figure 4 is a perspective view of a hairspring, the outermost coil of which is provided with an integral plate in which an opening for receiving a pillar is formed;

[0045] - Figure 5 is a perspective view of a hairspring equipped with a plate attached to the free end of the outermost coil of the hairspring, in which an opening for receiving a pillar is formed;

[0046] - Figure 6 is a perspective view of a hairspring, the outermost coil of which is bent to form an opening for receiving a pillar;

[0047] - Figure 7 is a schematic view showing an example in which the pillar is integral with the balance bridge plate of the timepiece movement.

[0048] - Figure 8 is a schematic view showing an example in which the holding structure includes a support member formed by a stud, at the top of which a pillar is mounted and which is arranged in a recess formed in the balance bridge plate by a friction fit;

[0049] - Figure 9 shows an example in which the holding structure includes a support member formed by a stud, at the top of which a pillar is mounted and which is arranged in a recess formed in the balance bridge plate by a threaded connection, with a washer interposed between the balance bridge plate and the support member to prevent any untimely loosening;

[0050] - Figure 10 is a perspective view of a hairspring, the outermost ring of which is bent to form a hook portion for receiving a support pillar;

[0051] - Figure 11 and 12 show, respectively, the holding structure arranged in an assembled state and a disassembled state in a manner of supporting a component, the component being disposed in a recess formed in a balance cock, the outermost ring of the hairspring being covered by a locking member provided with a support pillar that is received in an opening formed in the component. DETAILED DESCRIPTION

[0052] The present invention stems from the following general inventive concept: to provide a mechanical assembly that allows the second free end of the outermost ring of the hairspring of a hairspring balance assembly of a watch movement to be attached without using an adhesive. By eliminating the use of adhesives, the present invention avoids problems associated with such materials, particularly in terms of aging and creep as well as appearance; more specifically, especially in the field of high-end watches, it is clearly desirable to avoid, as much as possible, having to resort to using adhesives for assembling mechanical components. According to another advantage thereof, the mechanical assembly according to the present invention allows the second free end of the outermost ring of the hairspring to be attached in a detachable manner, so that when the watch is returned to the factory, if necessary, the positioning of the hairspring can be readjusted. Another advantage of the mechanical assembly according to the present invention is that it allows the second free end of the outermost ring of the hairspring of a watch movement to be attached without causing mechanical stress in this second end, particularly in the plane in which the coil windings of the hairspring extend, which is highly advantageous for the timekeeping accuracy of the hairspring balance assembly.

[0053] An attachment assembly 1 according to the present invention, generally indicated by the general reference numeral 1, is used to detachably attach a hairspring 2 of a watch movement including a balance cock 4.

[0054] More specifically, as Figure 1 shown, the attachment assembly 1 further includes a holding structure 8 and a detachable locking member 10 in addition to the hairspring 2.

[0055] From Figure 1As can be seen, the hairspring 2 includes a coil winding 12 that extends between a first free end 14 of a first inner ring 16 and a second free end 18 of an outermost ring 20. According to the present invention, the second free end 18 of the outermost ring 20 of the hairspring 2 includes an attachment structure, which in a preferred and non-limiting embodiment of the present invention is in the form of an opening 22 in which a retaining structure 8 engages to ensure that the hairspring 2 is detachably attached via its outermost ring 20. The size of the opening 22 is designed such that, in the natural rest position of the hairspring 2, the edge 24 of the opening 22 does not contact the retaining structure 8 engaged in the opening 22. Thus, attaching the hairspring 2 by means of the attachment assembly 1 according to the present invention does not cause any stress in the hairspring 2 in the X-Y plane in which the hairspring 2 extends, and thus does not affect the timekeeping accuracy. A detachable locking member 10 is used to ensure the detachable attachment of the second free end 18 of the outermost ring 20 of the hairspring 2, and the locking member 10 preferably engages on the retaining structure 8 following the hairspring 2 by being pressed in.

[0056] According to a specific embodiment of the present invention, the opening 22 provided in the second free end 18 of the outermost ring 20 of the hairspring 2 preferably but not exclusively has an elongated shape, the major axis 26 of which extends in the continuation of the outermost ring 20 (see Figure 3 ).

[0057] In Figures 4 to 6 the embodiment shown, the opening 22 has an elongated shape, the center of the radius of curvature R of which is on the center 27 of the coil winding 12.

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

[0059] In an embodiment of the present invention, the second free end 18 of the outermost ring 20 of the hairspring 2 in which the opening 22 is formed is integrally formed with the hairspring 2 assembly. Thus, the outermost ring 20 of the hairspring 2 can be provided with a plate 28 integrally formed, and the opening 22 is formed in the plate 28 ( Figure 4 ). Conversely, the plate 28 can be attached to the second free end 18 of the outermost ring 20 of the hairspring 2 by connection processes such as welding, for example ( Figure 5 ). The opening 22 can also be formed by means of a bent portion 30 of the second free end 18 of the outermost ring 20 of the hairspring 2 ( Figure 6 ).

[0060] The retaining structure 8 includes a strut 32 that is arranged to engage within the opening 22 formed in the second free end 18 of the outermost ring 20 of the hairspring 2.

[0061] In a first embodiment, the strut 32 is integrally formed with the balance bridge plate 4 of the watch movement ( Figure 7 ).

[0062] According to another embodiment of the present utility model, the retaining structure 8 includes a support member 34 formed by a pile member 36, and a support column 32 is installed on the top of the pile member 36. The support member 34 is disposed in a recess 38 formed in the balance cock 4. The support member 34 is positioned in the recess 38 by a friction fit ( Figure 8 ) or by a threaded connection ( Figure 9 ). If the support member 34 is threadedly connected in the recess 38, the support member 34 has an external thread, and the recess 38 is provided with complementary threads on the inner side wall 40. In order to prevent the support member 34 from being accidentally loosened, a retaining member 42 such as a spring washer can be disposed between the balance cock 4 and the support member 34 ( Figure 9 ).

[0063] The detachable locking member 10 is a washer attached to the support column 32 in a detachable manner (usually by pressing).

[0064] In its simplified embodiment, the attachment assembly 1 according to the present utility model allows adjustment of the runout of the hairspring balance wheel assembly 44. In addition, in its preferred embodiment, the attachment assembly 1 according to the present utility model not only allows adjustment of the runout of the hairspring balance wheel assembly 44, but also allows adjustment of the time difference of such a hairspring balance wheel assembly 44.

[0065] As described above, the attachment assembly 1 according to the present invention is first installed by joining the opening 22 in the second free end 18 of the outermost ring 20 of the hairspring 2 to the post 32 of the support member 34. Generally, the dimensions of the entire mechanical assembly formed by the hairspring 2, the hairspring balance wheel assembly 44 equipped with such a hairspring 2, and the retaining structure 8 are designed such that when the post 32 of the support member 34 is joined within the opening 22 of the hairspring 2, the edge 24 of the opening 22 of the hairspring 2 does not contact the post 32 joined within this opening 22. However, in the very few cases where this is not so, the present invention advantageously allows the support member 34 to pivot slightly in one direction or the other until the post 32 no longer contacts the edge 24 of the opening 22 of the hairspring 2. Thereafter, the hairspring balance wheel assembly 44 is adjusted for its runout by rotating the hairspring balance wheel assembly 44 about the balance axis 46 until the impact pin 48 of the balance wheel disc 50 is aligned with the escapement line passing through the balance axis 46 and the escapement fork axis (not shown in the figure). Once the runout of the hairspring balance wheel assembly 44 has been adjusted, it is again ensured that the post 32 of the support member 34 does not contact the edge 24 of the opening 22 of the hairspring 2; as before, in the very few cases where this is not so, the present invention allows the support member 34 to be rotated again, thereby moving the post 32 away from the edge 24 of the opening 22 of the hairspring 2, and then a washer is press-fitted onto the post 32 to lock the second free end 18 of the outermost ring 20 of the hairspring 2. Conversely, that is, if no contact is observed between the edge 24 of the opening 22 of the hairspring 2 and the post 32 of the support member 34, the hairspring 2 can be directly locked by attaching a washer to the post 32.

[0066] Of course, it can be understood that if the support member 34 is integrally formed with the balance bridge 4, the support member 34 cannot pivot.

[0067] In Figure 2 the preferred embodiment of the present invention shown in perspective in, not only can the runout of the hairspring balance wheel assembly 44 be adjusted, but also the rate difference of the hairspring balance wheel assembly 44 can be adjusted. The operation of adjusting the rate difference of the hairspring balance wheel assembly 44 occurs after the second free end 18 of the outermost ring 20 of the hairspring 2 has been locked by attaching a washer to the post 32. At this time, the support member 34 pivots clockwise or counterclockwise, thereby driving the second free end 18 of the outermost ring 20 of the hairspring 2.

[0068] More specifically, Figure 3It is shown that the hairspring 2 includes a flexible element 52, which is composed of a pivot 54 and a rigid part 60. The pivot 54 includes 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 to the elongated fixed support 62 in the transverse direction on one hand, and are connected to the pivot 54 by moving towards each other on the other hand. Therefore, the first flexible blade 56 and the second flexible blade 58 move towards each other from the fixed support 62 to the pivot 54. The fixed support 62 is attached to an attachment part 62a integrated with the balance staff 4. The second free end 18 of the outermost coil 20 of the hairspring 2 is connected to the pivot 54. In the figure, a variable torque is applied to an additional blade that connects the outermost coil 20 to the rigid part 60, so that the stiffness of the additional blade is changed, and thus the stiffness of the hairspring 2 is changed, thereby changing the timekeeping difference of the hairspring balance assembly 44. For this purpose, the hairspring 2 extends beyond its flexible element 52 through a lever 64. The lever 64 bypasses the coil winding 12 and terminates at a plate 28, in which an opening 22 according to the present invention is provided. The torque is transmitted to the hairspring 2 via the lever 64 and the flexible element 52. For a complete description of the hairspring 2 used in this improved embodiment of the present invention, please refer to the European patent application EP21202213.1 filed by the applicant.

[0069] It goes without saying that the present invention is not limited to the embodiments just described, and those skilled in the art can conceive various simple modifications and alternative embodiments without departing from the scope of the present invention defined by the appended claims.

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

[0071] Generally speaking, the manufacturing tolerances of the hairspring 2 (especially when it is made of silicon) are very strict, so the position of the geometric center of the opening 22 formed in the free end 18 of the outermost coil 20 of the hairspring 2 can be known very precisely in advance, which enables the pillar 32 to be accurately positioned on the balance staff 4, or the support member 34 corresponding to the assembly formed by the stud 36 and the pillar 32 to be positioned in the recess 38 provided in the balance staff 4 for this purpose.

[0072] If the hairspring 2 is made of silicon, the free end 18 of the outermost circle 20 of the hairspring 2 in which the opening 22 is formed is integrally formed with the hairspring 2 assembly. If the hairspring 2 is made of a metal alloy, the opening 22 for receiving the pillar 32 of the support member 34 can be formed by simply bending the free end 18 of the outermost circle 20 of the hairspring 2. Typically, the plate 28 can also be attached to the free end 18 of the outermost circle 20 of the hairspring 2 by welding, and the opening 22 for receiving the pillar 32 of the support member 34 is formed in the plate 28.

[0073] In very few cases, after the hairspring 2 is installed and the pillar 32 is engaged in the opening 22 formed in the free end 18 of the outermost circle 20 of the hairspring 2, it is observed that the edge 24 of the opening 22 makes mechanical contact with the pillar 32 at any point. Advantageously, the present invention allows the support member 34 to pivot until no mechanical contact is observed. Therefore, in any case, the present invention can ensure that the free end 18 of the outermost circle 20 of the hairspring 2 remains stationary without causing any stress in the X-Y plane in which the hairspring extends, which is very beneficial for the timekeeping accuracy of the hairspring balance wheel assembly 44.

[0074] In a simplified alternative embodiment of the present invention, the free end 18 of the outermost circle 20 of the hairspring 2 has only one attachment point, that is, the pillar 32 of the support member 34, which is engaged in the opening 22 formed in the free end 18 of the outermost circle 20 of the hairspring 2 and serves as an external hairspring stud, so that only the wobble of the hairspring balance wheel assembly 44 can be adjusted.

[0075] In an improved alternative embodiment of the present invention, there are two attachment points, and the hairspring 2 is preferably made of silicon; in this case, with two attachment points, both the wobble and the time difference of the hairspring balance wheel assembly 44 can be adjusted. In addition, it can be understood that thanks to the present invention, the time difference of the hairspring balance wheel assembly 44 can be finely adjusted 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 present invention, the time difference of the hairspring balance wheel assembly 44 can also be adjusted by changing the stiffness of the hairspring 2. Some hairspring balance wheel assemblies can even be adjusted in both ways simultaneously.

[0076] The pile member 36 of the support member 34 may be threaded to allow for fine adjustment of the height along the axis Z perpendicular to the support surface provided by the support member 34. To prevent the threaded support member 34 from accidentally loosening, a retaining member 42 of, for example, the spring washer type may be arranged between the threaded support member 34 and the surface of the balance cock 4 to lock the threaded pile member 36. Thanks to the present utility model, by changing the stiffness of the hairspring 2 attached to the balance staff 46 via the inner stud 66, the timekeeping error of the hairspring balance assembly 44 can be adjusted, which is much simpler than adjusting the timekeeping error of the hairspring balance assembly by changing the inertia of the balance wheel (e.g., by adding or removing material, or by moving a counterweight or a screw, etc.).

[0077] According to Figure 10 In a specific embodiment of the present utility model as shown, the attachment structure may have an open geometry, such as being shaped like a hook portion 68, wherein the retaining structure 8 is engaged to ensure that the hairspring 2 is detachably attached via its outermost coil 20. The retaining structure 8 is of the strut 32 type, arranged in the internal space defined by the hook portion 68 and held in place by the retaining member 42. Generally, there should be no mechanical contact between the hook portion 68 and the strut 32 when the hairspring 2 is assembled. However, if this is not the case, the support member 34 can be rotated until no mechanical contact is observed.

[0078] According to a specific embodiment of the present utility model, the retaining structure 8 includes a support member 70, which is arranged in a recess 72 formed in the balance cock 4. The support member 70 is arranged in the recess 72 by a friction fit or by a threaded connection. The free end 18 of the outermost coil 20 of the hairspring 2 rests on the support member 70 and is covered by a locking member 74, and a strut 76 is provided on the lower side of the locking member 74 and is received in an opening 78 formed in the support member 70.

[0079] List of reference numerals

[0080] 1. Attachment assembly

[0081] 2. Hairspring

[0082] 4. Balance cock

[0083] 8. Retaining structure

[0084] 10. Removable locking member

[0085] 12. Coil winding

[0086] 14. First free end

[0087] 16. First inner coil

[0088] 18. Second free end

[0089] 20. Outermost ring

[0090] 22. Opening

[0091] 24. Edge

[0092] 26. Major axis

[0093] 27. Center

[0094] 28. Plate

[0095] 30. Bending part

[0096] 32. Strut

[0097] 34. Support member

[0098] 36. Pile member

[0099] 38. Recess

[0100] 40. Inner wall

[0101] 42. Holding member

[0102] 44. Hairspring balance wheel assembly

[0103] 46. Balance staff

[0104] 48. Impact pin

[0105] 50. Balance wheel disc

[0106] 52. Flexible element

[0107] 54. Pivot

[0108] 56. First flexible blade

[0109] 58. Second flexible blade

[0110] 60. Rigid part

[0111] 62. Fixed support

[0112] 62a. Attachment member

[0113] 63. Additional blade

[0114] 64. Lever

[0115] 66. Inner pile

[0116] 68. Hook part

[0117] 70. Support member

[0118] 72 Recess

[0119] 74. Locking member

[0120] 76. Support

[0121] 78. Opening

Claims

1. An attachment assembly (1) for removably attaching a hairspring (2) to a timepiece movement, the timepiece movement including a balance cock (4), characterized in that, On the one hand, the attachment assembly includes the hairspring (2), and on the other hand, a holding structure (8) for the hairspring (2) and a detachable locking member (10). The hairspring (2) includes a coil winding (12) that extends between a first free end (14) of a first inner coil (16) and a second free end (18) of an outermost coil (20). The second free end (18) of the outermost coil (20) of the hairspring (2) includes an attachment structure. The holding structure (8) engages in the attachment structure to ensure that the hairspring (2) is detachably attached through its outermost coil (20). The attachment structure is dimensioned such that, in the natural rest position of the attachment structure, the attachment structure does not contact the holding structure (8) engaged in the attachment structure. The detachable locking member (10) for detachably attaching the second free end (18) of the outermost coil of the hairspring (2) is mounted on the holding 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 hairspring (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) has an elongated shape and has a major axis (26) located in a continuation of the outermost coil (20).

4. The attachment assembly (1) for a hairspring (2) for detachably attaching a timepiece movement, according to claim 2, 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 integrally formed with the hairspring (2).

5. The attachment assembly (1) for detachably attaching a hairspring (2) of a timepiece movement, as claimed in claim 2, 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 hairspring (2).

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

7. The attachment assembly (1) for a hairspring (2) for detachably attaching a watch 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 hairspring (2).

8. The attachment assembly (1) for detachably attaching a hairspring (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 hairspring (2) by welding.

9. The attachment assembly (1) for detachably attaching a hairspring (2) of a timepiece movement, according to any one of claims 2 to 8, characterized in that, The holding structure (8) includes struts (32; 76) arranged to engage within the opening (22) formed in the second free end (18) of the outermost coil (20) of the hairspring (2).

10. The attachment assembly (1) for detachably attaching a hairspring (2) of a timepiece movement, according to claim 9, characterized in that, The struts are integrally formed with the balance cock (4) of the timepiece movement.

11. The attachment assembly (1) for detachably attaching a hairspring (2) of a timepiece movement according to claim 9, characterized in that, The holding structure (8) includes a support member (34) formed by a stud (36), and the struts are mounted on top of the stud (36).

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

13. The attachment assembly (1) for detachably attaching a hairspring (2) of a timepiece movement according to claim 12, characterized in that, The support member (34) is arranged within the recess (38) by a friction fit.

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

15. The attachment assembly (1) for detachably attaching a hairspring (2) of a timepiece movement according to claim 14, characterized in that, In order to prevent the support member (34) from being inadvertently unscrewed, a retaining member (42) is provided between the balance cock (4) and the support member (34).

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

17. The attachment assembly (1) for detachably attaching a hairspring (2) of a timepiece movement according to claim 9, characterized in that, The detachable locking member (10) is a washer detachably attached to the struts.

18. The attachment assembly (1) for detachably attaching a hairspring (2) of a timepiece movement according to claim 17, characterized in that, The washer is press-fitted onto the strut.

19. The attachment assembly (1) according to claim 9, characterized in that, The holding structure (8) includes a support member that is disposed within a recess formed in the balance cock (4) and covered by a locking member provided with the strut, the strut being received within an opening formed in the support member.

20. The attachment assembly (1) for a hairspring (2) for detachably attaching a watch movement, according to any one of claims 2 to 8, characterized in that, A flexible element (52) for changing the stiffness of the hairspring (2) is provided between a second free end of the outermost turn of the hairspring and a lever (64) surrounding the coil winding (12), the opening (22) being provided in the free end of the lever.

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