HK1245425B - Anti-shock device for a timepiece movement - Google Patents

Description

Shockproof devices for watch movements

Technical Field

The present invention relates to anti-vibration devices for timepieces. Such anti-vibration devices are typically associated with bearings that guide the rotation of pivoting elements of a timepiece movement, particularly the balance wheel. They are also known as shock absorbers, dampers, or vibration absorbers. More specifically, the invention relates to damping the axial vibrations to which the pivoting elements are subjected and the mechanical stresses imposed on the pivot shafts caused by such axial vibrations.

Background Art

A common anti-shock device for a timepiece comprises an elastic element bearing on or exerting pressure on at least one endstone comprising a bearing for the anti-shock device, the endstone constituting a stop for a pivot inserted into the bearing in the direction of the axis of rotation of the associated pivoting element. When the pivot presses against the endstone in the event of a vibration, the anti-shock device is arranged so as to generate a restoring force on the associated pivot via the endstone. An "endstone" is understood to be any structure made of any suitable material that defines an axial bearing surface for the pivot.

Such anti-vibration devices usually include a mechanical spring whose dimensions are determined empirically, according to practical rules, to achieve the best compromise between mechanical stability during operation and elastic resistance to mechanical deformations. In practice, it is desirable to have a relatively stiff shock absorber that does not cause axial movements of the pivoting element in the event of even small shocks, while ensuring a shock-absorbing function even for strong shocks that could lead to large axial (positive or negative) accelerations of the pivoting element that could damage the pivot.

In particular, conventional anti-shock devices for balances with hairsprings, parachutes, and lyre springs are dimensioned so that, due to the prestress of the springs that make up these parachutes and lyre springs (which defines a threshold), they are activated only at relatively high vibration accelerations (between 200 g and 500 g, g being the acceleration of the Earth). Above this threshold, the springs deform and absorb part of the vibration energy. However, due to the low mechanical shock absorption capacity of the metal strips used, most of the energy is recovered in the balance wheel. Even for relatively small shocks, the balance wheel pivot is likely to deform locally. This deformation has a considerable impact on the chronometric accuracy of the watch and is generally ignored due to the lax chronometric standards for watches subject to one-meter vibrations (a difference of 60 seconds per day).

Summary of the Invention

One object of the present invention is to provide a timepiece movement equipped with at least one effective anti-shock device, which offers a solution to the problem of damage to the pivots in the event of shocks, even strong ones.

To this end, the invention relates to a timepiece movement as defined in claim 1 .

Thanks to the features of the invention, which will be described in detail below, the anti-vibration device exhibits a lower resistance to stronger shocks, while ensuring good stability against smaller shocks. Indeed, the stiffness of the anti-vibration device according to the invention means that it no longer behaves like a mechanical spring, generating a restoring force substantially proportional to the axial displacement of the endstone. Instead, it exerts a higher force when the displacement is zero, which then decreases at least during the initial portion of the vibration-damping travel that can be generated by the endstone.

In a primary embodiment, the first and second magnets and the highly magnetically permeable member are aligned in a direction substantially parallel to the axis of rotation of the pivoting member, the first and second magnets having opposite polarities in that direction.

In a preferred variant, the highly magnetically permeable element is fixed to the first magnet.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the accompanying drawings, given by way of non-limiting example, in which:

- FIG1 is a perspective bottom view of an anti-vibration device according to a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of a timepiece movement incorporating the anti-shock device of FIG. 1 , passing through the anti-shock device.

- Figure 3 is a side view, partially in section, of a magnetic system similar to that included in the anti-vibration device of the present invention.

FIG. 4 shows a graph of the total magnetic force exerted on the mobile magnet as a function of the distance between the mobile magnet and the ferromagnetic disk for the magnetic system of FIG. 3 .

5 shows a graph of the elastic force exerted by the leaf spring of the anti-vibration device of FIG. 1 on the pivot of the pivoting element, and a graph of the total force exerted by the anti-vibration device as a function of the displacement of this pivot bearing against the endstone along its axis of rotation.

- FIG. 6 is a top view of an anti-vibration device according to a second embodiment of the present invention.

FIG. 7 is a partial cross-sectional view of a timepiece movement incorporating the anti-shock device of FIG. 6 , passing through the device.

- FIG8 shows a graph of the elastic force exerted by the lyre spring of the anti-vibration device of FIGS. 6 and 7 on the pivot of the pivot element, and a graph of the total force exerted by the anti-vibration device as a function of the displacement of this pivot bearing against the endstone along its axis of rotation.

DETAILED DESCRIPTION

1 to 5 , a first embodiment of a timepiece movement 22 will be described below, comprising a pivoting element 24 , a bearing 28 in which pivot 26 of the pivoting element is arranged, and an anti-shock device 30 associated with this bearing.

Typically, the anti-vibration device 30 includes an elastic member 32 that exerts a force on an endstone 36, which acts as a stop for the pivot 26 in the direction of the axis of rotation of the pivoting element. When the pivot is pressed against the endstone in the event of a vibration, the anti-vibration device is arranged so that the endstone can generate a restoring force on the pivot 26. According to the present invention, the anti-vibration device also includes a magnetic system 40 comprising two magnets 42 and 44 and a highly magnetically permeable element 46, which is positioned between the two magnets and fixed to one of the magnets. The two magnets are respectively fixed to a support 48 of the anti-vibration device and to the elastic member 32, so that (particularly in the event of certain vibrations) when the elastic member temporarily undergoes elastic deformation under a certain pressure exerted by the pivot on the endstone, relative movement over a certain relative distance D is imparted between the two magnets (see FIG. 3 ). More specifically, the magnet 44, which is integral with the elastic member, is arranged so that, in the event of a strong axial vibration on the pivoting element, it undergoes a reciprocating movement, which is indicated by the double-headed arrow in FIG. 2 . In the absence of vibrations, the elastic member is in a defined rest position, as is the magnet carrying the elastic member. It will be noted that in this rest position, the elastic member may have an initial elastic deformation. In this case, the elastic member is said to be "prestressed".

In an unusual and highly advantageous manner, as will be described below with reference to Figures 3 and 4, the two magnets 42 and 44 are arranged so as to produce between them, in conjunction with the highly magnetically permeable element 46, a total magnetic attraction force in a first section of the aforementioned relative distance, and a total magnetic repulsion force in a second section of this relative distance, which corresponds to a greater separation distance between the first and second magnets than that corresponding to the first section (reference symbol E in Figure 3). In addition, the magnetic system 40 and the elastic element 32 are arranged so that, for the entire relative distance, a certain restoring force is retained by the total force exerted on the pivot 26 by the anti-vibration device in the event of a shock.

Specific variations of the first embodiment shown in FIG2 are as follows:

- a highly magnetically permeable element 46 fixed to a magnet 42 integral with a support 48;

- the highly magnetically permeable element consists of a plate having a central axis substantially coinciding with the magnetization axis of the magnet 42;

When the elastic element is in its rest position, the two magnets 42 , 44 and the highly magnetically permeable magnet 46 are aligned in a direction substantially parallel to the axis of rotation 50 of the pivoting element 24 ;

- The magnets 42 and 44 have opposite polarity along their alignment direction.

In particular, according to the variant shown in Figures 1 and 2, the two magnets are cylindrical and the plate is in the form of a disc, for example made of ferromagnetic material.

With reference to Figures 3 and 4 , the magnetic system 40 and its operation will be described below. For this purpose, Figure 3 illustrates a magnetic system 52 similar to magnetic system 40. Thus, magnetic system 52 includes a first magnet 4, a highly magnetically permeable element 6 integral with the first magnet, and a second magnet 8 movable along a displacement axis relative to the assembly formed by the first magnet 4 and element 6. As described above, element 6 is positioned between the first and second magnets, in contact with or in proximity to the first magnet. Specifically, element 6 is bonded to the first magnet, as shown in Figure 3 . In another embodiment, the first magnet can be press-fitted into the highly magnetically permeable element, in which case the highly magnetically permeable element can, for example, take the form of a cylindrical housing open at one end to accommodate the first magnet. In a preferred embodiment, the distance between element 6 and the magnet 4 integral therewith is less than or substantially equal to one-tenth of the length of the magnet along its magnetization axis. The first magnet 4 and element 6 constitute the first portion of the magnetic system, and the second magnet 8 constitutes the second portion of the system. Element 6 is made, for example, of carbon steel, tungsten carbide, nickel, FeSi or FeNi, or other alloys containing cobalt, such as (CoFeNi) or (CoFe). In an advantageous variant, the highly magnetically permeable element is made of iron or cobalt-based metallic glass. Element 6 is characterized by its saturation magnetic field _BS and magnetic permeability μ. Magnets 4 and 8 are made, for example, of ferrite, FeCo or PtCo, or rare earth materials such as NdFeB or SmCo. These magnets are characterized by their remanent magnetic fields Br1 and Br2.

Highly magnetically permeable element 6 has a central axis 10 that substantially coincides with the magnetization axis of first magnet 4 and also with the magnetization axis of second magnet 8. Magnets 4 and 8 have opposite magnetization directions. These first and second magnets thus have opposite polarities and are capable of relative movement over a certain relative distance D. In the example shown in FIG3 , magnet 4 is fixed and magnet 8 is movable, so that the direction of relative movement between them is substantially along central axis 10, which thus defines a displacement axis. It will be noted that axis 10 is linear, but this is a non-limiting variation. In the first embodiment of the present invention, the displacement axis is substantially an arc of a circle, and the central axis of element 46 is substantially tangential to this curved displacement axis. In this case, as a first approximation, the behavior of magnetic system 40 is similar to that of magnetic system 52. This is particularly true if the radius of curvature is large relative to the maximum possible distance between element 46 and magnet 44, as is the case in the first embodiment of the present invention. In a preferred variant, as shown in Figure 3, the dimensions of the element 6 in a plane orthogonal to the central axis 10 are greater than the dimensions projected onto this plane by the first magnet 4 and the second magnet 8. It will be noted that in the case where the second magnet moves against the element 6 at the end of the magnetic attraction stroke, it advantageously has a hardened surface or a thin layer of hard material at its surface.

The two magnets 4 and 8 are arranged to magnetically repel each other, so that in the absence of the highly magnetically permeable element 6 , the repulsive force tends to move the two magnets away from each other.

However, unexpectedly, the arrangement of element 6 between the two magnets causes the magnetic forces between them to reverse when the first and second parts of the magnetic system are at a very short distance from each other, thereby generating a total magnetic attraction force between the two parts. FIG4 is a graph, whose curve 54 represents the magnetic interaction force between the first and second parts of the magnetic system 52 as a function of the separation distance E between the two magnets, or as a function of the relative distance D between the mobile magnet 8 and the highly magnetically permeable element 6. It can be observed that, over a first portion D1 of the relative distance, magnet 8 is generally subjected to an attractive magnetic force, which tends to hold magnet 8 against element 6 or, if they move apart, to return magnet 8 toward element 6. Secondly, element 6 and the two magnets are arranged such that, over a second portion D2 of the relative distance, the second magnet 8 is generally subjected to a repulsive magnetic force. This second portion corresponds to a separation distance between the first and second parts (and, therefore, to a distance D between element 6 and magnet 8) that is greater than the separation distance corresponding to the first portion of the relative distance. The second section is limited by a maximum distance D _max , which is generally defined by stops _that limit the separation distance of the mobile magnets.

The total magnetic force is a continuous function of the distance between the components and has a zero value at the distance D _inv . Therefore, when the distance between magnet 8 and element 6 is greater than the distance D _inv , the magnet experiences a total magnetic repulsion force that tends to move element 6 away. However, when the distance between element 6 and mobile magnet 8 is less than the distance D _inv , magnet 8 experiences a total magnetic attraction force that tends to move magnet 8 closer to element 6 and, if there is no resistance, to bring magnet 8 into contact with element 6 and then retain it in this position. This is a characteristic function of magnetic system 52, which is advantageously utilized in the anti-vibration device according to the present invention. The inverse distance D _inv is determined by the geometry of the three magnetic components that make up the magnetic system and their magnetic properties.

The anti-vibration device 30 according to the first embodiment and its behavior resulting from its integration with the magnetic system 40 according to the present invention will be described in greater detail below. The elastic member 32 is formed by a leaf spring having a first end 56 and a second end 58, the first end being fixed to the support 48 by means of a screw 60, and the second end carrying the second magnet 44. According to one advantageous variant, the endstone 36 is positioned between the first and second ends, as seen in projection of the leaf spring onto a general plane. The bearing 28 comprises a base 62 fixedly arranged within an opening in the support 48. This base has a hole in its center in a conventional manner, into which the pivot 26 enters. The pivot element 24 (here, a pendulum staff (not shown)) has a bearing surface 70 that limits its displacement along the axis 50 in a conventional manner, and which is brought into contact with a surface defined by the base at the periphery of the hole. The bearing 28 also comprises a seat 64, into which the endstone 36 is inserted. In the illustrated variant, this is a magnetic bearing. The base thus also carries the magnet 66 and the closing jewel 68. The base is also part of the anti-vibration device. It is arranged in the housing formed by the base 62 and the closing plate 72 fixed to the support 48, so that in the event of a shock, when the support surface 70 moves against the base, the base undergoes axial movement over at least a distance corresponding to the maximum displacement that the pivot 26 can perform. A short tube 74 is fixed to the leaf spring 32 on the side of its end 58 so as to rest against the base or the closing jewel. The anti-vibration device acts via this tube on the component integral with the endstone. It will be noted that the invention is not limited to magnetic bearings. Therefore, in another variant, a conventional bearing is provided, having a base containing a jewel hole and an endstone, which can have a flat surface facing the pivot.

The magnetic system and the elastic element are arranged so that, in the rest position of the anti-shock device, the endstone or the base to which it is fixed remains resting against the bearing support or the base of the bearing, while the force exerted on the endstone by the associated pivot is less than a limit value, preferably greater than the force of gravity acting on the pivoting element, in particular the balance with hairspring. In a particular variant, the elastic element is prestressed in the rest position of the anti-shock device so that the endstone remains immobile over a wide range of values of the force exerted by the mobile element subjected to axial acceleration in the event of a shock.

FIG5 shows a graph of the spring force exerted by the leaf spring 32 and the total force exerted by the anti-vibration device 30, as a function of the displacement DP of the endstone and, consequently, of the pivot 26 resting thereon, along its axis of rotation 50. It will be noted that there is a linear relationship (to a first approximation) between the displacement DP and the distance D of the magnetic system 40. In a known manner, the spring force varies proportionally with the displacement DP. Its graph is represented by an affine line 76, shown in dashed form. Curve 78 provides a graph of the total force exerted by the anti-vibration device on the assembly carrying the endstone and, consequently, on the pivot 26 resting thereon, as a function of its displacement DP. This curve corresponds to the sum of the spring force and the total magnetic force generated by the magnetic system 40. It can be observed that this total force (restoring force) is greater than the spring force in a first section DP1, which extends between the distance DP _R corresponding to the rest position of the anti-vibration device and the distance DP _inv corresponding to the endstone position in which the total magnetic force exerted on the magnet 44 is zero. Then, between the distance DP _inv and the distance DP _max (at which distance DP _max the pendulum staff 24 rests against the peripheral surface of the hole in the base of the bearing), the total force is less than the spring force because the total magnetic force now opposes the spring force, which reduces the total force exerted on the pivot of the pivoting element.

The anti-vibration device according to the present invention exhibits excellent behavior, as shown by curve 78. At least for endstone displacement distances less than DP _inv , the force exerted on the pivot resting on the endstone is maximum for the rest distance DP _R of the anti-vibration device. Once the force exerted by the pivot on the endstone increases above the maximum value for the rest position of the anti-vibration device, the endstone is moved away from its rest position, at which point the total force exerted on the pivot 26 decreases rapidly, which immediately ensures greater movement of the endstone and good vibration damping in the rest position. In the example shown in FIG5 , the leaf spring has a stiffness close to standard stiffness, but its prestress is reduced by a factor of approximately 30% to 40% compared to the standard prestress, while providing standard stability for the anti-vibration device in its rest position.

The dependence of the total force on the pivot as a function of the axial displacement of the balance and the corresponding displacement of the anti-shock device allows the following operation (for a variant with a balance having a weight of approximately 40 mg and an element made of ferromagnetic material interposed between the two magnets of the magnetic system):

1) For acceleration vibrations less than 400g, the anti-vibration device remains stationary due to the superimposed magnetic attraction and the prestress of the spring.

2) For shocks exceeding 400g, and in particular 1000g, the spring-loaded mobile magnet separates from the ferromagnetic element, the magnetic force rapidly decreases and then reverses, in this case against the elastic force exerted by the spring. Once the threshold force for the axial movement of the anti-vibration device has been exceeded, the total force is reduced, at least over the majority of the possible displacements of the pivot, because the deformation of the anti-vibration device becomes immediately significant and allows the balance wheel to reach the mechanical stop very quickly. This allows the kinetic energy of the balance wheel to be absorbed while limiting the force exerted on the pivot over the entire shock-attenuating travel.

Once the vibration ends, the anti-vibration device can return to its initial position because the total force remains positive (restoring force) and exceeds the friction force. The reversal of magnetic force that occurs when the mobile magnet moves close enough to the ferromagnetic element also ensures that mechanical hysteresis is completely eliminated and the bearing is re-centered after the vibration.

The following advantages result from the features of the anti-vibration device according to the invention:

- the anti-vibration device works like a real shock absorber (unlike traditional anti-vibration devices);

- the possibility of dimensioning the anti-vibration device by optimizing the prestressing force (and thus the handling of small vibrations when bearing stability is required) and the damping response to large vibrations;

- after a large shock, the magnetic attraction ensures that the anti-shock device is repositioned in its given rest position and that the base (which defines the axis of rotation of the balance wheel) is recentered;

Since the maximum force is preferably the total force generated by the anti-shock device in its rest position, the forces to which the balance staff is subjected in the event of large shocks are reduced.

With reference to Figures 6 to 8, a timepiece movement 82 incorporating a second embodiment of an anti-shock device according to the invention will be described below. A bearing and its associated anti-shock device 86 are arranged within an opening in plate 84. Elastic element 88 is a lyre spring having two branches 89 and 90, arranged to exert pressure on endstone 36A. In a variant (not shown), the two branches press against a base to which the endstone is fixed. The anti-shock device comprises a first magnetic system 40A and a second magnetic system 40B, each of which is similar to magnetic system 40 described in relation to the first embodiment. Therefore, the distinct operation of these two magnetic systems will not be described again here.

The two magnetic systems are associated with two structures 92 and 94, respectively, which are fixed to the two branches 89 and 90, respectively, substantially in their middle regions. These two structures each carry two magnets 44A and 44B, each of which constitutes a mobile magnet of the corresponding magnetic system. Thus, the two branches are associated with the first and second magnetic systems, respectively, and each carries, via structures 92 and 94, a mobile magnet 44A and 44B, respectively, which cooperate with the fixed magnets 42A and 42B, respectively. Each magnetic system also includes a highly permeable magnetic element 46A, 46B, respectively, which is integral with the fixed magnet of the corresponding magnetic system.

It will be noted that each lyre spring branch 89, 90 is conventionally held axially at its ends by angled projections of the upper ring of the bearing base 62A. Therefore, when subjected to stress, the lyre spring undergoes its greatest elastic deformation in the central region of these branches. It will also be noted that each branch presses against the endstone substantially in its center. Preferably, but not by way of limitation, the two structures 92 and 94 are integral with the lyre spring and, in particular, possess a greater rigidity than the corresponding branches, particularly through their greater thickness, as shown. However, in another variant, the structures have the same thickness as the lyre spring branches for ease of manufacture, but have a larger cross-section. In another variant, however, the rigidity of the mobile magnet support structure is no greater than that of the branches, so that, in the event of significant vibrations, the mobile magnet travels a longer distance than the endstone.

The arrangement of two magnetic systems, respectively associated in a symmetrical manner with the two elastic lyre spring branches, is advantageous because, given the same elastic deformation of the two branches, it allows each branch to exert the same pressure on the endstone, or more generally on the mobile bearing assembly 96. This ensures a consistent behavior of the anti-shock device, and in particular of the endstone 36A, in the event of axial vibrations, in a general plane perpendicular to the axis of rotation of the balance wheel.

FIG8 shows a graph 76A showing the spring force exerted by the lyre spring on the endstone, and thus on the pivot 26 resting thereon, as a function of the endstone's axial displacement, and a graph 100 showing the total force exerted by the anti-vibration device 86 on the pivot as a function of said axial displacement. It will be noted that the variant shown does not provide mechanical prestressing of the anti-vibration device in its rest position; it only has a magnetic attraction force that ensures the immobilization of the anti-vibration device within its static operating range (here corresponding to the rest position with a displacement DP equal to zero) up to a certain maximum static force. The predominance of the magnetic force in the rest position allows the total force to drop substantially below the maximum static force once the anti-vibration device enters its dynamic operating range and is thus tilted. This ensures that the maximum force exerted on the pivot resting on the endstone is the maximum force of the anti-vibration device in its non-tilted state. Thus, in the event of a sudden movement of the pivot due to a large axial shock, the balance wheel shifts, encountering little resistance until it encounters the stop formed by the base of the bearing. It will be noted that, by acting on the annular bearing surface of staff 24 , this stop is able to protect it in the event of strong shocks.

Finally, the stiffness of the lyre spring and the dimensions of the two magnetic systems are set so that the total force exerted by the anti-shock device retains a restoring force higher than the friction force, so as to ensure the return of the anti-shock device to its initial position and proper re-centering of the mobile bearing assembly 96 after a shock that generates a force higher than the maximum force generated on the mobile bearing assembly 96 in the static situation (an important performance for ensuring good chronometric performance of the watch movement).

It will be noted that, advantageously, in the second embodiment, the two bearings of the sprung balance are equipped with shock-absorbing means of the type described above.

Claims (11)

1. A watch movement (22; 82) comprising a pivot element (24), a bearing (28), and a shock-absorbing device (30; 86) associated with the bearing, wherein a pivot (26) of the pivot element is arranged in the bearing (28), the shock-absorbing device comprising an elastic element (32; 88) arranged to apply pressure on at least one jack (36; 36A), the jack constituting a stop for the pivot in the direction of the axis of rotation (50) of the pivot element, the shock-absorbing device being arranged such that when the pivot presses against the jack under vibration, the shock-absorbing device is capable of generating a restoring force on the pivot via the jack; characterized in that the shock-absorbing device further comprises a magnetic system (40; 40A, 40B) comprising a first magnet (42) and a second magnet (44) and a high-transmittance magnetic element (46) arranged between and with the first magnet and the second magnet. A magnet is integrally formed, and a first magnet and a second magnet are respectively fixed to the support (48) of the shock-absorbing device and the elastic element, so that when the elastic element undergoes elastic deformation under the pressure applied to the jack by the pivot under vibration, relative movement occurs between the first magnet and the second magnet at a certain relative distance; these first magnets and the second magnet are arranged such that, between the first magnet and the second magnet and associated with the high-permeability magnetic element, a total magnetic attraction is generated in a first segment of the relative distance, and a total magnetic repulsion is generated in a second segment of the relative distance, the separation distance between the first magnet and the second magnet corresponding to the second segment being greater than the separation distance corresponding to the first segment; and the magnetic system and the elastic element are arranged such that, for the entire relative distance, the total force applied to the pivot by the shock-absorbing device under vibration retains a restoring force. 2. The watch movement according to claim 1, characterized in that the first magnet and the second magnet are aligned with the high-transparency magnetic element in a direction substantially parallel to the rotation axis (50) of the pivot element, and the first magnet and the second magnet have opposite polarities in this direction. 3. The watch movement according to claim 2, wherein the high-transparency magnetic element comprises a plate having a central axis substantially coincident with the magnetization axis of the first magnet. 4. The watch movement according to claim 2, wherein the distance between the high-transparency magnetic element and the magnet integral with the element is less than or substantially equal to one-tenth of the length of the magnet along its magnetization axis. 5. The watch movement according to any one of the preceding claims, characterized in that the high-transparency magnetic element is fixed to the first magnet. 6. The watch movement according to claim 5, characterized in that the magnetic system and the elastic element are arranged such that: in the rest position of the shock-absorbing device, the elastic element keeps the piercing or the base fixing the piercing against the support or the base integral with the support, while the force applied to the piercing by the pivot is less than a limit value greater than the gravity acting on the pivot element. 7. The watch movement according to claim 6, wherein the elastic element (32) is prestressed at the rest position of the shock-absorbing device. 8. The watch movement according to any one of claims 1 to 4, characterized in that the high-transmittance magnetic element is made of iron or cobalt-based metallic glass. 9. The watch movement according to any one of claims 1 to 4, characterized in that the elastic element is a leaf spring (32) having a first end and a second end, the first end being fixed to the support member, the second end (58) carrying a second magnet, and the piercing pin being located between the first end and the second end in the projection on the overall plane of the leaf spring. 10. The watch movement according to any one of claims 1 to 4, characterized in that the elastic element is a lyre spring (88) having two branches (89, 90) arranged to apply pressure on the jewel holder or on a base for fixing the jewel holder; the magnetic system defines a first magnetic system, and the shock-absorbing device further includes a second magnetic system similar to the first magnetic system, the two branches being associated with the first magnetic system and the second magnetic system respectively, and each carrying a magnet corresponding to and cooperating with the second magnet, wherein the corresponding magnet corresponds to the first magnet fixed to a support member of the shock-absorbing device. 11. The watch movement according to any one of claims 1 to 4, wherein the pivoting element is a balance wheel.