CH718076A2 - Mechanical movement watch with force control mechanism. - Google Patents

Abstract

The watch (1) has a mechanical movement with a force control mechanism, and of the jumping seconds type. The force control mechanism is arranged in a going train (5, 8, 9, 10) between a power source and an escapement wheel set (11) linked to an oscillating oscillator (14) to drive the wheel set exhaust always in the same direction of rotation. The escape wheel set (11) meshes with a fixed seconds wheel (2). A rotary blocking element (7) is arranged to cooperate, with a stop member (3) in connection with said fixed second wheel (2) to block in a stop mode or release in a jump mode said cog finishing according to the angular position of said fixed second wheel (2). A flexible guide (4) with elastic strips (4a) is fixed on the one hand to the fixed second wheel (2) and on the other hand to a support of the movement. The flexible guide (4) pre-armed is provided to rotate the fixed seconds wheel (2) and the escapement mechanism linked to the oscillator (14) at each half-oscillation of the oscillator in the mode of stop. In the jump mode, the going train (5, 8, 9, 10) is released allowing the rotary blocking element (7) to rotate, and to rotate a second pinion (5) coaxial with said fixed second (2) to jump one second in jump mode. This also makes it possible to reset the flexible guide (4) in connection with the second pinion (5), while making it possible to block the rotary blocking element (7) and the going train (5, 8, 9 , 10) for stop mode following jump mode. According to a preferred embodiment of the invention, a tourbillon cage (15) is moved in rotation with the second pinion (5), the escapement mechanism with the oscillator (14) and the fixed second wheel (2) in jump mode.

Description

Field of the invention

The invention relates to a watch with a mechanical movement with a force control mechanism, such as the force due to gravity when wearing the watch and of the jumping second type. Preferably, the force control mechanism may be a tourbillon mechanism mounted at the escapement. The tourbillon carriage surrounds the escapement mechanism and preferably the carriage performs a complete rotation every minute with in particular 60 jumps of a second performed.

Background of the invention

[0002] As a reminder in watchmaking, a tourbillon, also called a "rotating cage", is a horological complication, added to the escapement mechanism, intended to improve the precision of mechanical watches by counterbalancing the disturbances of the isochronism of the resonator due to Earth's gravity. The fundamental criterion, which characterizes a tourbillon, in relation to a carousel in particular, is the presence of a fixed gear train on which the tourbillon cage meshes. Generally, the tourbillon cage is rotatably mounted between two fixing points.

[0003] Gravity is also taken into account to compensate for all disturbances in the isochronism of the resonator. The escapement is coupled to the resonator. It interacts with it once or twice per period of oscillation. The angle traveled by the resonator during the interaction is called the lift angle. The rest of the resonator's path is called an additional angle or arc.

[0004] During the additional angle, the resonator can be in contact with the escapement (exhaust at rubbing rest) or without contact (free escapement). During the lift angle, the escapement performs two main phases, which are release (or count) and impulse (or sustain).

[0005] In a horological complication, the purpose of the jumping seconds is to display the second in steps of a whole second, which corresponds on a dial of 60 seconds at an angle of 6° per second. This jumping second is often associated with constant force mechanisms that take advantage of the particular construction of this jumping second. Deadbeat seconds or fixed seconds mechanisms also come close to these constructions with the particularity of being able to stop the seconds at will like a chronograph.

[0006] Several jumping second mechanisms exist in watchmaking literature and patents, and are applied. According to some examples, in a Jacquet Droz watch, there is the 1195 movement of Blancpain. For Breguet's Marie Antoinette, there is the mechanism with the deadbeat seconds.

[0007] In the patent application WO 2011/157797 A1, there is described a mechanism for advancing by periodic jump of a pivoting cage carrying a wheel and an escapement pinion and an anchor cooperating with the wheel and a spiral balance. . In addition, it comprises retaining means to authorize or prohibit the pivoting of said cage according to the movements or not. There are also stop means for authorizing or prohibiting, depending on their angular position, the pivoting of the retaining means. A constant force device causes the retaining means to cooperate periodically. This device comprises a whip intended to perform complete turns.

[0008] The principle of these mechanisms described is to retain the going train between the escapement and the second by a mechanism, while an additional spring maintains the escapement with a constant force in a stopping phase. At the end of the second, which is counted by the escapement, the freed gear train allows the movement to be advanced by one second. Thus the display therefore advances and the mechanism is reset in the jump phase.

[0009] In such a mechanism operating at frequencies close to one second, the torques available in watchmaking are very low. This is why these mechanisms are difficult to implement and generally unreliable.

[0010] In the mechanism of the Blancpain 1195 movement, there is a stop system which distributes part of the torque in the blocking of the stop phase to compensate for friction. This gives a jumping second having an angular displacement of about 20% in the stop phase for an 80% jump.

[0011] It may also be envisaged to reduce the frequency and to produce dead minutes instead of seconds, which facilitates construction.

[0012] Some of these mechanisms can get out of sync after complete disarming, and go into a blocking position. This requires a stop system linked to a power reserve mechanism, which will stop the mechanism before complete unwinding.

[0013] In a mechanism described in patent EP 1 528 443 B1, there is proposed a constant force device for a watch, with a deadbeat second. This device makes it possible to move an axis of a mobile on a rocker driven by an energy storage spring, which tends to cause the rocker to pivot. The device comprises a pinion of a first seconds wheel of the movement, which meshes with a transmission pivotally mounted on this rocker, and which meshes with the pinion of a second seconds wheel defining the wheel set. The rocker carrying a finger must adapt to cooperate with a ratchet toothing of a stop wheel, which meshes with the first seconds wheel. When the finger is engaged with a radial flank of the ratchet, the gear train is blocked, in particular consisting of the first seconds wheel and the transmission without force transmission from the first seconds wheel and the transmission. The second seconds wheel is controlled by the escapement and only turns when it is moved by the balance wheel. The winding of the spring is ensured by the displacement of the rocker in the opposite direction, for which the spring exerts on the rocker a lower torque than that exerted by the barrel spring on the rocker, when the stop wheel is released. The device thus makes it possible to adapt the winding/unwinding cycle according to the number of teeth of the stop wheel. This device makes it possible to ensure a jumping seconds function, but the main drawback is that it is not easy to achieve with a large number of components necessary to perform this operation. In addition, there is a movement of a mobile at the time of the jumping second, which is not desired.

The utility model CN 209014916 U describes a tourbillon watch mechanism having a toothed wheel. The toothed wheel is composed of a central passage portion of an axis, connected by spring-type metal coils to an inner wall of a ring gear with outer peripheral teeth.

[0015] Patent EP 3 356 690 B1 describes a timepiece component having a flexible pivot of the type with well-known separated crossed blades, and having means for adjusting the position of the point of intersection of the blades.

Summary of the invention

[0016] For the present invention, it is desired to produce a jumping second display and still of constant force in a simpler way, without mobile movement and without risk of desynchronization at the end of winding and thus limiting friction for use. especially in a tourbillon movement.

[0017] The object of the invention is therefore to overcome the disadvantages of the state of the art by providing a watch with a mechanical movement with a compensation or force control mechanism of the jumping second type overcoming the disadvantages of the devices of the aforementioned prior art.

[0018] To this end, the invention relates to a mechanical movement watch with a compensation or force control mechanism of the jumping second type, which comprises the characteristics defined in independent claim 1.

Particular embodiments of the watch with mechanical movement with compensation mechanism or force control of the jumping second type are also described in dependent claims 2 to 18.

[0020] An advantage of the watch with a mechanical movement with a force control mechanism according to the invention lies in the fact that it comprises a second fixed energy SFA to accumulate the energy necessary to maintain several oscillations of the mechanism of escapement with the oscillator, in particular in a stop mode before switching to a jump mode. Depending on the frequency of the resonator fitted with a traditional escapement, the SFA fixed second maintains a few oscillations of the resonator or oscillator without any part of the gear train coming from the barrel being driven. Preferably, the fixed second SFA releases a blocking element, such as a whip after a certain number of oscillations, in particular to cause the tourbillon cage to move by 6° clockwise (SAM) and the going train coming from the barrel defining a seconds of the jumping seconds type. In the case of the tourbillon according to an exemplary embodiment at least at the fifth pulse of the 2.5 Hz oscillator, the whip is released and by it, the intermediate wheel linked to the whip, the middle wheel, the large middle wheel and the barrel to drive the tourbillon carriage in a step of 6° in a direction opposite to the accumulation of the fixed second. Mainly, the tourbillon cage can be moved angularly after a certain number of oscillations defining one second. By this arrangement without mobile moving, the risk of desynchronization at the end of winding is not affected.

[0021] Advantageously, the fixed seconds wheel SFA is intended to move in the stopping phase by a certain number of small steps following the oscillations of the spiral spring of the oscillator linked to the escapement mechanism, which is of the Swiss anchor. In this stopping phase or stopping mode, the fixed seconds wheel SFA rotates counter-clockwise while being driven in rotation by a flexible guide with elastic blades, which is pre-armed. A movable portion of this flexible guide is fixed to one face of the fixed second wheel SFA, while a fixed portion of this flexible guide is fixed to a support of the watch movement, such as a plate. The mobile portion of this flexible guide is preferably fixed directly below the fixed second wheel SFA. The flexible guide is mounted through an axial opening, coaxially with a second pinion, which is the second and tourbillon pinion.

[0022] Advantageously, the flexible guide with elastic blades (spring blades) comprises several elastic blades in series connecting more massive parts including the mobile and fixed portions of the flexible guide, and possibly other intermediate portions. The flexible guide with elastic blades in series can thus be produced with a more robust structure capable of ensuring the rotation of the fixed second SFA with a restoring torque advantageously used to replace the spring of the force control mechanism and with better support. axial. In addition, such flexible guidance with elastic strips makes it possible to have an absence of friction, wear and dissipation of energy, as well as an absence of play and precise guidance.

Brief description of the drawings

[0023] The aims, advantages and characteristics of the watch with a mechanical movement with a compensation mechanism or force control will appear better in the following description, particularly with regard to the drawings in which: FIG. 1 represents a three-dimensional view from below of the main elements of the watch movement with a force control mechanism and of the jumping second type according to the invention, FIG. 2 represents a bottom view of the mechanical watch movement with a force control mechanism of the jumping second type without the middle wheel and the intermediate wheel according to the invention, FIGS. 3a, 3b and 3c represent plan views of three embodiments of flexible guides with elastic blades or pivots with flexible blades with higher torques and better axial retention in order to be able to be connected to the fixed second wheel SFA according to the invention, FIG. 4 represents a view from below of another schematic embodiment of a movement. ent mechanical watch with the going train without a tourbillon and the force control mechanism according to the invention, and FIG. 5 represents a transverse section from bottom to top of the mechanism at the center of the tourbillon as represented above partially at figure 1.

Detailed description of the invention

In the following description, various organs or elements of the mechanical watch movement with a force control mechanism and of the jumping second type, which are well known in this technical field, will only be briefly described.

[0025] It should first be noted that the watch with a mechanical movement with a force control mechanism and of the jumping second type can be with a tourbillon whose cage encloses an oscillator and an escapement mechanism as explained below. after, or according to a traditional mechanical movement without a tourbillon, which will be explained later with reference to figure 4.

[0026] Figures 1 and 2 show part of a mechanical watch movement 1 which is shown without the energy source, such as the barrel which is the mainspring and which is connected, in this case, to a rocket connected by a chain to the barrel drum for its drive. There is also not shown a large medium wheel, which is driven in rotation by a toothing on the periphery of the rocket according to a traditional embodiment. This energy is applied in the form of a torque to the pinion of the middle wheel 10.

Figures 1 and 2 therefore represent part of a mechanical watch movement comprising a going train 5, 8, 9, 10 in which is arranged a force control mechanism of the mechanical movement 1 of the watch. This force control mechanism may be similar to a constant force device. The going train is arranged between a source of energy, not shown, which is preferably a spring barrel, and an escapement mechanism, for example with a Swiss lever 13 and having an escape wheel set 11 in the form of a wheel, retained and released alternately by an oscillator 14, which is preferably a spiral balance wheel and whose energy for maintaining it in oscillation is provided by said escapement wheel set 11. The escapement wheel set 11 is arranged to be able to rotate in the same direction of rotation with each half-oscillation of the oscillator 14.

[0028] The escape wheel 11 meshes with a second wheel 2 which is subsequently defined as a fixed second wheel SFA. This second wheel 2 is called a fixed second wheel SFA, even if it is not fixed in its operation. This SFA 2 fixed second wheel can rotate counter-clockwise (SIAM) to maintain the operation of the escapement mechanism linked to the oscillator in a stop mode, and rotate clockwise of a watch (SAM) in a jump mode to perform a jump corresponding to 1 second. Both in the form of execution with a tourbillon, and in the form of execution without tourbillon, there is always a stop phase and a jump phase so as to make a jump on the display corresponding to one second .

[0029] To do this, the fixed second wheel SFA 2 preferably comprises peripheral toothing meshing with an escapement toothed pinion 12 coaxial with said escapement wheel set 11. As explained below in a stop phase of the finishing gear train, the fixed seconds wheel SFA 2 rotates counter-clockwise (SIAM) by the restoring force of the flexible guide 4 and drives the escapement wheel set 11 with each half-oscillation of the oscillator 14 via the escapement toothed pinion 12 so as to maintain the operation of the oscillator and of the escapement mechanism in this stopping phase.

During this stopping phase, the fixed second wheel SFA 2 pivots in SIAM on its flexible guide 4 around the cage 15 of the tourbillon without touching it, which is stopped. This SIAM pivoting of the SFA 2 takes place until the moment of the release of the going train 5, 8, 9, 10 by which a jump of one second is made by the tourbillon cage 15 and its second pinion 5 , carrying with it the fixed second wheel SFA 2, which is linked to the escapement wheel set 11, in the clockwise jump phase SAM.

To define the stop phase and the jump phase, the force control mechanism comprises on the one hand a preferably rotary locking element 7 arranged to cooperate with a stop member 3 in connection with the wheel second fixed SFA 2 in stop mode. As illustrated in Figures 1 and 2, this stop member 3 can be a rake 3, rotatably mounted at a first end of the rake 3 around an axis 33 arranged for example between a movement mounting plate and a bridge of average not shown. A second free end of the rake 3 comprises, in a blocking part, an edge portion in the shape of a finger 3b disposed freely inside a guide housing between two teeth of a cam 6. The cam 6 is fixed integrally of said fixed seconds wheel SFA 2 close to its center so as to drive the rake 3 in rotation in each direction. The second free end of the rake 3 also comprises a stopper 3a, such as a pallet 3a, arranged on a side opposite the edge portion 3b and arranged to block the rotary blocking element 7 in a stop mode. The pallet 3a can be made of a hard material reducing friction with the blocking element 7 in contact with the pallet 3a in a stopping phase. This stop piece, which is the pallet 3a, can be made of a friction-reducing material such as ruby.

To drive the SFA fixed second wheel 2 in rotation, in particular in a stop mode, a flexible guide 4 with elastic blades 4a or spring blades, which is pre-armed, is connected directly to the SFA fixed second wheel. 2. The flexible guide 4 acts as a spring on the fixed second wheel SFA 2. To do this, the flexible guide 4 comprises a movable portion 4c with at least one opening 17 but preferably two openings 17 for fixing on one side of the fixed second wheel SFA 2. Preferably, the flexible guide 4 is fixed to an underside of the fixed second wheel SFA 2.

It should be noted that elastic blades 4a are defined, these blades can be of rectangular, hexagonal or even round cross-section. These elastic blades have a geometry: length and section which must be well determined to ensure the spring function to drive the SFA 2 fixed second wheel in rotation with the necessary torque. Reference may be made to the work W. H. Wittrick indicated below, for the production of flexible guides 4 with elastic blades 4a.

As shown in Figure 5, at least one fixing means 27 in or through the opening or openings 17 is thus provided to fix the fixed second wheel SFA 2 on the movable portion 4c of the flexible guide 4. Preferably , this fixing means 27 can be at least one material extension of the fixed second wheel SFA 2 to form a single piece with the wheel. Two extensions of material 27 can be provided to be inserted, for example by force respectively, into the two openings 17 of the movable portion 4c of the flexible guide 4 to ensure good support and without protruding from each opening 17. A border can also be provided. around each extension of material 27 and which can come directly from material with the corresponding extension of material to ensure a space between the lower face of the fixed second wheel SFA 2 and an upper face of the flexible guide 4.

[0035] The flexible guide 4 further comprises a fixed portion 4b with at least one opening 16, but preferably two openings 16 to be mounted and fixed by means of a screw and nut assembly, not shown, on a support of the watch movement , such as a turntable. Several elastic strips 4a or portions of elastic strips connect the mobile portion 4c to the fixed portion 4b as well as intermediate portions possibly between the mobile 4c and fixed 4b portions. The flexible guide 4 is mounted through an axial opening, coaxially with the second pinion 5, and around an axial tube of the fixed second wheel SFA 2 coaxial with the axis of the second pinion 5.

It should also be noted that it may be envisaged to have two fixing openings provided in the fixed second wheel SFA 2 to receive by force insertion two extensions of material from the movable portion 4c of the flexible guide 4 of equivalent but inversely to what has been described above. The fixing means can also be a screw and nut assembly passing through openings in the movable portion and in the fixed second wheel SFA 2, but with this type of mounting, too much space is wasted. Similarly, the fixing of the fixed portion 4b of the flexible guide 4 on the plate can be carried out by means other than the screw and nut assembly, taking the example of the fixing of the fixed second wheel SFA 2 on the flexible guide 4. In the rest position, that is to say as soon as the transition from jump mode to stop mode, the elastic strips 4a of the flexible guide 4 must be pre-stressed to accumulate mechanical energy to rotate the fixed second wheel SFA 2 especially counter-clockwise (SIAM).

The rotation of the fixed second wheel SFA 2 also drives the escapement wheel set 11 via an escapement pinion 12 coaxial with the escape wheel set of the Swiss lever escapement mechanism 13. This is advantageous for maintaining the escapement mechanism with the oscillator 14 in function in this stopping phase by the mechanical energy accumulated in the flexible guide 4 with elastic blades 4a acting on the fixed second wheel SFA 2 to make it turn counter-clockwise (SIAM).

[0038] The rake 3 is connected without the action of a spring to a cam 6 fixed to the fixed second wheel SFA 2 to lock or release said going train according to the angular position of said fixed second wheel SFA 2 by the retention of a whip 7, as a blocking element. This whip 7 comes into contact with a stop piece 3a of the blocking part of the rake 3. This stop piece is a pallet 3a, as described above.

In the case presented, the fixed seconds wheel SFA 2 can turn by 5 small steps corresponding to an angle of 6° representing 1 second in the opposite direction. The whip 7 is itself driven by the going train and retained by the stopper 3a. Once released at the end of the stopping phase, the rotation of the rake 3 releases the whip 7 which triggers the jump phase. During the jump phase, the whip 7 performs a rotation corresponding to a jump of 1 second, driven by the going train, in the case shown, a half-turn. The going train likewise drives the tourbillon cage 15 via the second pinion 5 and the fixed second wheel SFA 2 in the direction of clockwise (SAM), which resets the flexible guide 4. This flexible guide 4 of the fixed second wheel SFA 2 is arranged to accumulate energy when said fixed second wheel SFA 2 is driven in SAM during the jump phase and to restore it to said fixed second wheel SFA 2 in SIAM during the phase stop.

[0040] Generally in the stopping phase, several half-oscillations of the oscillator 14 occur before the release of the going train. This means that the frequency of oscillator 14 is generally higher than 1 Hz and for example in this case can be set to 2.5 Hz. step corresponding to a half-oscillation (alternation), one can count 5 half-oscillations of the oscillator 14 in the stop phase until the moment of the release of the rotary blocking element 7 for the jump phase. The flexible guide 4 linked to the fixed second wheel SFA 2 must therefore provide energy during the 5 half-oscillations of the oscillator 14 or the carriage is stopped, and be reset during the jump of the said carriage 15.

[0041] The flexible guide 4 represented in FIG. 2 comprises a fixed portion 4b arranged in a housing with a large V-shaped opening of the mobile portion 4c, which comprises an axial opening which is coaxial with the axis of the pinion of second 5. Two through openings 16 are provided in the fixed portion 4b and arranged on the same line with the axial opening. Two through openings 17 are provided in the movable portion 4c and arranged practically on the same line with the axial opening.

In this embodiment, five successive elastic blades 4a connect a first inner side of the movable portion 4c to a first inner side of the fixed portion 4b. A first elastic blade 4a from the movable portion 4c is connected to a first intermediate central portion. A second elastic blade 4a from the first intermediate central portion is connected to a first intermediate peripheral portion. A third elastic blade 4a from the first intermediate peripheral portion is connected to a second intermediate central portion. A fourth elastic blade 4a from the second intermediate central portion is connected to a second intermediate peripheral portion. A fifth elastic blade from the second intermediate peripheral portion is connected to a first interior side of the fixed portion 4b.

Five successive elastic blades 4a connect a second inner side of the movable portion 4c to a second inner side of the fixed portion 4b. A second elastic blade 4a from the movable portion 4c is connected to the same first intermediate central portion. A second elastic blade 4a from the same first intermediate central portion is connected to the same first intermediate peripheral portion. A third elastic blade 4a from the first intermediate peripheral portion is connected to the same second intermediate central portion. A fourth elastic blade 4a from the second intermediate central portion is connected to the same second intermediate peripheral portion. A fifth elastic blade from the second intermediate peripheral portion is connected to a first interior side of the fixed portion 4b.

It is noted that the fixed part 4b is arranged inside between the movable portion 4c and the two intermediate peripheral portions. In addition, the two intermediate central portions form an arc of a circle centered on the axis of the second pinion 5, and the same applies to the two intermediate peripheral portions also centered on the axis of the second pinion 5.

However, more or less half-oscillations of oscillator 14 can be provided in the stop phase depending on the oscillation frequency of oscillator 14. Each half-oscillation must be equal to 0.2 s for a 2.5 Hz oscillator. The number n of half-oscillations of the oscillator can therefore be chosen only for an oscillator frequency greater than 1 Hz, for example for at least n = 3 half-oscillations for 1.5Hz or n = 5 for 2.5Hz. The number of small steps performed by the SFA 2 fixed second wheel in the stop phase must correspond to a jump of 1 second in the jump phase.

It can also be envisaged to make period jumps greater than 1 second, which generalizes the above rule to an oscillator frequency higher than the frequency of the display jumps. In this way, it could be considered to skip every minute.

With reference to the embodiment shown in Figures 1 and 2, the rotary locking element 7 is a whip in the form of a rotatably mounted rod at its center. The whip is secured to an axial locking pinion 8 to mesh with an intermediate wheel 9 of the going train. The blocking rake 3 is rotatably mounted at a first end opposite the blocking part, which includes the stopper 3a. As previously indicated, the rotary locking rake 3 comprises at a second end, the edge portion 3b, which is a finger 3b guided inside a housing made in the cam 6, which is integral with the second wheel fixed SFA 2. This cam 6 formed of two teeth with the housing between the two teeth controls the pivoting of the rake 3, which comprises the blocking pallet 3a arranged on a side opposite the finger 3b. As indicated above, this pallet 3a can be made of a hard material reducing friction with the blocking element 7 in contact with the pallet 3a in a stopping phase.

The pallet 3a is arranged to cooperate in support with said blocking element 7, which is a whip, to block said going train in a stop phase, or to release said blocking element 7 and said going train in a jump phase. The whip 7 comprises a first blocking rod part and a second blocking rod part with respect to its center which includes the axial blocking pinion 8. Once the pallet 3a is no longer in contact with the first part of stem of the whip 7 or the second part of the stem of the whip 7, in the jump phase, the whip 7 is set in rotation and rotates through 180° to allow the rotation of the going train before a new locking position of the going train in a stop mode. In jump mode, the tourbillon carriage 15 is rotated 6° clockwise (SAM) by the going train to add one second to the time. The SFA fixed second wheel 2 is driven with the cage 15, which is linked to the coaxial second pinion 5 of 6° angle to reset the flexible guide 4 of the SFA rake. The fixed second wheel SFA 2 is driven by cage 15, since the escapement mechanism also rotates with the cage. The rearming of the flexible guide 4 takes place quickly, which means that the end of the whip 7 comes back directly into contact with the stopper 3a once the whip 7 has turned 180°. As soon as this new blockage occurs, a new stop phase operation takes place.

It is understood that the 180° rotation of the whip 7 before a new stop is directly and dynamically linked to the inertia of the moving components. In particular the inertia of whip 7, which has the fastest rotation, is of great importance. A construction of the whip 7 favoring low inertia, such as can be obtained with the LIGA manufacturing means in Nickel or Nickel Phosphorus or the DRIE manufacturing means in silicon, will therefore be preferred. These manufacturing means allow the realization of whip 7 of precise and advantageous geometry to limit the inertia of the whip 7.

During the stop phase, the escape wheel set 11 is driven in a first direction of rotation (SIAM) by the fixed second wheel SFA 2, which corresponds to each half-oscillation of the oscillator 14 maintained . 5 small steps are taken by the escape wheel set 11 driven in rotation by the fixed second wheel SFA 2 and via the escapement pinion 12. This disarms said flexible guide 4 which drives the fixed second wheel SFA 2 and moves said pallet 3a in the direction of the release of the whip 7.

[0051] As the going train is blocked in the stop mode with the exception of the fixed second wheel SFA 2, the flexible guide 4 linked to the fixed second wheel SFA 2 releases energy to rotate said fixed second wheel SFA 2 to drive the escapement wheel set 11. In jump mode, as soon as the whip 7 is no longer in contact with the pallet 3a, the going train via the axial blocking 8 of the whip 7, is arranged to cause the said fixed second wheel SFA 2 to pivot via the second pinion 5 and the tourbillon cage 15. This fixed second wheel SFA 2 with the tourbillon cage 15 rotates of 6° in a second direction of rotation, which is the clockwise direction (SAM) opposite to said first direction of rotation imposed on the escapement wheel set 11 by the fixed second wheel SFA 2, according to a stroke corresponding to an angular jump of one second. The tourbillon cage 15 is pivoted by 6° in the clockwise jump mode (SAM) in a direction opposite to the pivoting of the fixed seconds wheel SFA 2 in the stop phase . At the end of the jump, the whip 7 comes back to rest against the pallet 3a to again block the going train with the exception of the fixed second wheel SFA 2. The whip 7 with its two stem parts of the same length forms a 180° rotation to change from jump mode to next stop mode.

It should be noted that the whip 7 is linked to the going train and to the barrel by the intermediate wheel 9 to make it turn around its central axis at each jump mode of 1 second and to release the going train 5 , 8, 9, 10, as well as the cage 15 of the tourbillon in this embodiment. The force of the drive spring(s) of the going train is greater than the mechanical energy accumulated in the flexible guide 4. Thus, the going train is immediately put into operation as soon as it is released, which makes it possible to maintain good synchronism in time, also given that the escapement mechanism and the oscillator 14 are kept in operation during the stop phase even if the going train is blocked, except for the fixed seconds wheel SFA 2.

[0053] All the elements of the force control mechanism described above are mounted on a plate, an average bridge, a whip bridge, which are not shown so as not to overload the drawings.

As already mentioned above, the fixed seconds wheel SFA 2 comprises peripheral toothing meshing with the escapement toothed pinion 12 coaxial with the escapement wheel set 11. A middle wheel 10, which the going train comprises , has peripheral toothing meshing with the axial second gear pinion 5 coaxial with the fixed second wheel SFA 2, and whose axis of the second pinion 5 is connected to the cage 15 of the tourbillon. An intermediate wheel 9, which said going train also comprises, comprises an intermediate axial toothed pinion 19 meshing with the teeth on the periphery of the middle wheel 10. The intermediate wheel 9 comprises teeth on the periphery to mesh with said axial locking pinion 8 secured to the rotating blocking element 7, which is the whip. In the jump phase during the release of said going train, the intermediate axial toothed pinion 19 is arranged to let the middle wheel 10 turn, to enable it to pivot the tourbillon cage 15 via the second pinion 5 in said second direction of rotation SAM. In this second direction of rotation, the second pinion 5 supplies the energy to be stored in the flexible guide 4 by causing the fixed second wheel SFA 2 to turn in SAM.

To determine certain dimensional values according to the elements described above, it can be mentioned that the locking is done by a cog from the middle 10 and cun whip 7 of large diameter. This makes it possible to limit movement during the second, to limit friction, and to remove the pivoting of whip 7 from the surface occupied by the tourbillon carriage on the plate.

The high ratio between average 0.116 rpm and whip 0.5 t/sec (30 rpm) requires an intermediate mobile, which is intermediate wheel 9. This gives for example a ratio of average wheel 10 and intermediate wheel 9 at Z = 120/7 and m = 0.07 mm, and an intermediate wheel ratio of 9 and whip 7 at Z = 90/6 and m = 0.07 mm.

According to an alternative version, it is possible to drive the whip 7 from the cage 15 of the tourbillon directly. This requires making a tourbillon cage with external teeth meshing with the axial locking pinion 8, which is the whip pinion. The ratio between cage 15 and whip 7 is 1 rpm and whip 0.5 t/sec (30 rpm), can be done with a direct gear train. The external gear ratio of the tourbillon to the whip pinion is Z = 180/6 with m = 0.079 mm with a whip position identical to that of the previous version. However, the aesthetics of the tourbillon carriage is penalized by this external toothing.

[0058] The rest hold (stopping phase) on the pallet 3a of the rake 3 is 0.08 mm, which is comfortable for an escapement anchor, but probably a little low compared to the length of the rake. Construction can easily gain 25% by increasing the working radius of the 3a pallet. Anyway, the increase in displacement (for safety) on the pallet 3a increases the risks associated with friction.

As a reminder with reference for example to Figure 2, in the stopping phase, the going train is locked by the support of the whip 7 on the pallet 3a of the rake 3, and the escapement mobile 11 with its escapement pinion 12 is driven by the fixed second wheel SFA 2 with the flexible guide 4. In the jump phase, the pallet 3a of the rake 3 releases the going train. Seconds pinion 5 rotates 6° (one second) and resets flexible guide 4 for seconds wheel 2. SFA rack 3 locks the going train. The finger 3b of the rake 3 follows the movement of the cam 6 until the pallet 3a is no longer in contact with the end of the whip 7 to release the going train. We will not repeat all the other elements already mentioned before, which are sufficiently clearly shown in the previous figures.

[0060] Figures 3a, 3b and 3c show three different embodiments of the flexible guide 4, which can be fixed on the one hand under the fixed second wheel SFA 2, and on the other hand to a movement support, like a turntable. Such embodiments make it possible to have higher torques and better axial retention. These three embodiments are also different from the embodiment shown in Figures 1 and 2 and described above.

In Figure 3a, one can see the fixed portion 4b and the movable portion 4c of the flexible guide 4, which are both connected by several elastic blades 4a or spring blades, preferably two V-shaped elastic blades. Each of the elastic strips 4a connects a peripheral end of each fixed 4b and mobile 4c portion. There are also two through-openings 16 in the fixed portion 4b for attachment to a movement support, and two through-openings 17 in the movable portion 4c for attachment to the fixed second wheel SFA 2. The position of these through-openings 16, 17 is also dependent on the size of the fixed second wheel SFA 2 and its fixing parts. The fixed portion 4b further comprises an axial opening 25 for mounting the flexible guide 4 coaxially with the axis of the second pinion 5 and preferably on the axial tube of the fixed second wheel SFA 2.

In Figure 3b, one can see a fixed portion 4b and two movable portions 4c each arranged in a respective V-shaped housing of the fixed portion and symmetrically opposed to one another. The two mobile portions 4c are further connected by several elastic blades 4a in conjunction with an intermediate portion close to the axial opening 25 of the flexible guide 4. Two through openings 16 in the fixed portion 4b are made in the most compact portion, and a through opening 17 in each movable portion 4c is made. This structure in FIG. 3b makes it possible to increase the restoring torque and the overall rigidity by adding pairs of blades in parallel.

Finally in Figure 3c, one can see a fixed portion 4b arranged in a housing with a large V-shaped opening of the movable portion 4c, which this time comprises the axial opening 25. Two through openings 16 are provided in the fixed portion 4b and arranged on the same line with the axial opening 25. Two through openings 17 are provided in the movable portion 4c and arranged practically on the same line with the axial opening 25. In this embodiment, four successive elastic blades 4a connect a first inner side of the mobile portion 4c to a first inner side of the fixed portion 4b, where two first elastic blades 4a from the mobile portion 4c are connected by a first intermediate central portion, while two second blades elastic bands 4a from the fixed portion 4c are connected by a second intermediate central portion, the two intermediate blades being connected by a first intermediate peripheral portion medium. Four successive elastic blades 4a connect a second inner side of the movable portion 4c to a second inner side of the fixed portion 4b, where two first elastic blades 4a from the movable portion 4c are connected by the same first intermediate central portion, while two second elastic strips 4a from the fixed portion 4c are connected by the same second intermediate central portion, the two intermediate strips being connected by a second intermediate peripheral portion. This structure of FIG. 3c makes it possible to reduce the restoring torque and increase the angle of rotation by adding pairs of blades in series.

It is clear that the type of materials chosen to make these flexible guides 4 are materials used to make metal springs. In the different variants of flexible guide 4 described above, each flexible guide 4 can be in the form of a flat plate, in the thickness can be chosen substantially equivalent to the thickness of the central portion of the second wheel fixed SFA 2.

FIG. 4 additionally shows another schematic embodiment of a traditional mechanical watch movement with the going train and the force control mechanism according to the invention. Certain elements already described with reference to FIGS. 1 and 2 are found in this embodiment of the traditional movement, which does not include a tourbillon. But there is an accumulation of energy by a flexible guide 4 with crossed blades 4a connected to a stop member 3 connected to a crown 32 rotatably mounted on the fixed second wheel SFA 2. The flexible guide 4 comprises a fixed portion base, which can be fixed by screws 44 on a watch movement support, and a mobile portion which can be directly the crown 32 connected to the stopper 3. The elastic blades 4a are fixed for example by welding points 34 to the crown 32. In this case, as previously indicated, the flexible guide 4 must rotate the fixed second wheel SFA 2 with the stopper 3 in the anti-clockwise direction. (SIAM) in the motion stop phase.

In this embodiment, the two phases can again be specified, which are on the one hand the stop phase and on the other hand the jump phase. In the stopping phase, the going train 5, 8, 9, 10 is locked by the pressing of a tooth of the blocking element 7 against the stop member 3. The escapement wheel set 11 is driven by the fixed second wheel SFA 2 in the anti-clockwise direction (SIAM) by the action of the flexible guide 4 on the stop member 3 connected to the fixed second wheel SFA 2. In the jump phase, the stop member 3 is moved to release the going train. At the same time, the second pinion 5 rotates 6° clockwise (SAM) and driving the crown 53 via the satellite wheels 51, 52 also clockwise. , which also makes it possible to rearm the flexible guide 4. As the stopper 3 returns to the blocking position, the stopper 3 again locks the going train for a new operation in the stoppage phase for maintaining the functioning of the escapement mechanism linked to the oscillator.

[0067] Satellite wheels 51, 52 are also mounted in connection with the second pinion 5 coaxial with the second wheel 2. The stop member 3 can be an arcuate plate 3 pivoting about an axis and driven by the flexible guide 4 in this embodiment. In a stopping phase, the stop member 3 is in contact with a tooth of a locking element 7, which comprises in a central portion an axial locking pinion 8 to drive the intermediate wheel 9 having toothing in periphery. The blocking element 7 can comprise several teeth on its periphery to come into contact with the stop member 3 in the stop phase. In the jump phase, the blocking element 7 is released to rotate through an angle of 120° defining the second jump, as there are 3 blocking teeth.

In the stopping phase, the escapement wheel set 11 is driven by the fixed second wheel SFA 2 via its coaxial escapement pinion 12 engaged with a toothing on the periphery of the second wheel. fixed SFA 2. During the jump phase, this accumulated energy is supplied to the going train for the jump of the second. The middle wheel 10 driven by the intermediate pinion 19 of the intermediate wheel 9, has teeth on the periphery to mesh with the coaxial second pinion 5 for the second jump. Without direct influence on this jump phase, a large middle wheel 21 has a toothing on the periphery to mesh with a middle coaxial pinion 20. By the action of the second pinion 5, when the going train is in operation, the arrangement by the differential with the satellite wheels 51, 52 and the crown 53 makes it possible to rearm the flexible guide 4 of the SFA to find itself again in the stop mode with the stop member 3 blocking the blocking element 7 by one of his teeth.

It should be noted that the flexible guide 4 with crossed elastic blades 4a is well known. A particular configuration where the strips cross at seven-eighths of their length has already been disclosed in the work of W. H. Wittrick, „The properties of crossed flexure pivots and the influence of the point at which the strips cross“ in The Aeronautical Quarterly II( 4), pp. 272-292 (1951). In addition, pivots with flexible blades are known and described in particular in the work written by Simon Heinein, entitled "Conception of flexible guides" and published by PPUR presses polytechniques, in 2001.

The mobile or second wheel can be pivoted on a ball bearing carried by the plate.

[0071] Figure 5 shows a cross section from bottom to top of the mechanism at the center of the tourbillon as shown in part above with reference to Figure 1 or Figure 2. It is particularly noticeable in this figure that the second pinion 5 is the axis of the cage 15 of the tourbillon. The fixed seconds wheel SFA pivots concentrically to the axis of the tourbillon without touching it thanks to the holding in position of the flexible blade guide system. The tourbillon cage 15 encloses the escapement mechanism with the escapement mobile 11, the Swiss lever 13 and in connection with the oscillator 14 which is the balance spring.

[0072] The fixed second wheel SFA 2 meshes with the escapement pinion 12, which means that when the tourbillon cage 15 rotates every second, a rotation is also performed for the escapement mechanism linked to the oscillator. and also the SFA 2 fixed second wheel.

[0073] The flexible guide 4 is fixed on the fixed second wheel SFA 2. To do this, at least one fixing means 27 in or through the openings 17 is thus provided to fix the fixed second wheel SFA 2 on the movable portion of the flexible guide 4 as previously indicated. These fixing means 27 are preferably extensions of material of central portions of the second wheel 2 so as to be inserted by force into the openings 17 of the flexible guide 4. These extensions of material 27, as well as a border around these extensions of material come directly from material precisely with the rest of the second wheel to form a single piece.

As explained above, a finger-shaped edge portion 3b of the rake 3 is arranged freely inside a guide housing between two teeth of a cam 6 visible in Figure 2. Like the cam 6 is fixed integral with said fixed second wheel SFA 2 close to its center, this makes it possible to drive the rake 3 in rotation, which comprises on the other hand the blocking pallet 3a to block the whip 7 in a mode of stop. The whip 7 also includes an axial locking pinion 8, which can be rotated when the whip 7 is released in the jump mode. All other elements have already been explained above and will not be repeated again.

From the description which has just been given, multiple variant embodiments of the watch with a mechanical movement with a force control mechanism and of the jumping seconds type can be designed by those skilled in the art without departing from the scope of the invention defined by the claims. The mechanical movement can be a traditional mechanical movement with a fixed second wheel SFA also connected to drive or maintain the escapement wheel set with the oscillator in a stop phase.

Claims (18)

1. Mechanical movement watch (1) with a force control mechanism, and of the jumping second type, the force control mechanism being arranged in a gear train (5, 8, 9, 10) of the mechanical movement, which is arranged between a power source and an escapement wheel set (11) comprising an escapement mechanism linked to an oscillator (14) intended to be set into oscillation during normal operation by a drive generated by said power source to rotate said escape wheel (11) always in a single direction of rotation at each half-oscillation of the oscillator (14), said escape wheel (11) meshing with a seconds wheel (2), characterized in that said force control mechanism comprises a rotary blocking element (7) arranged to cooperate with a stop member (3) in connection with said fixed second wheel SFA (2) to block in a mode of stop or release in a jump mode said going train according to the angular position of said fixed second wheel SFA (2), and a flexible guide (4) with elastic blades (4a) fixed on the one hand to the fixed seconds wheel SFA (2) and on the other hand to a support of the watch movement, such as a plate, said flexible guide ( 4) with elastic blades (4a) being in a pre-armed state in a stop mode and arranged to drive in rotation the fixed seconds wheel SFA (2) and the escapement mechanism linked to the oscillator (14) at each half-oscillation of the oscillator (14) in stop mode, and a going train allowing the rotary blocking element (7) and a seconds pinion (5) coaxial with said SFA fixed seconds wheel (2) to rotate in order to perform a one-second jump in mode jump, and also making it possible to reset the flexible guide (4) with elastic blades (4a) while making it possible to block the rotary blocking element (7) and the finishing gear train for the stop mode following the jump mode . 2. Mechanical movement watch (1) according to claim 1, characterized in that the flexible guide (4) with elastic blades (4a) once pre-armed, is arranged to gradually move the stopper (3) in a stop mode up to a position of release of the rotary blocking element (7) on passing into a jump mode, and to drive the fixed second wheel SFA (2) in rotation and allow driving the escapement mechanism linked to the oscillator (14) in a stop mode. 3. Mechanical movement watch (1) according to claim 2, characterized in that the stop member (3) is a rake (3) rotatably mounted about an axis (33) at a first end and comprising at a locking part at a second end, a rim portion (3b) in the form of a tooth disposed in a guide housing of a cam (6) integrally fixed to the SFA fixed second wheel (2) near its center so as to be driven in rotation, and in that a stopper (3a), such as a pallet (3a) at the second end of the locking part, is arranged on a side opposite to the portion edge (3b) and arranged to block the rotary blocking element (7) in a stop mode. 4. Watch with mechanical movement (1) according to one of the preceding claims, characterized in that the rotary blocking element (7) is a whip (7), which is produced according to a LIGA or DRIE process. 5. Mechanical movement watch (1) according to one of the preceding claims, for which the watch is a tourbillon watch, the axis of a cage (15) of the tourbillon enclosing the escapement mechanism linked to the oscillator (14), is the second pinion (5), characterized in that in a stop mode with locking of the going train (5, 8, 9, 10), the fixed second wheel SFA (2) is arranged to drive by small steps in a first direction of rotation, the escapement wheel set (11) at each half-oscillation of the oscillator (14) by the action of the flexible guide (4) with elastic blades (4a) pre -armed and fixed to the SFA fixed second wheel (2), and that in a jump mode when the going train is released, the second pinion (5) is driven by a wheel (10) of the going train to perform an angular jump of one second corresponding to the number of small steps performed for driving the fixed second wheel SFA (2) in the stop mode, in a second direction s of rotation opposite to the first direction of rotation, the tourbillon cage (15), the escapement mechanism with the oscillator (14) and the fixed second wheel SFA (2) connected to the escapement mechanism being moved in rotation of an angle of 6° corresponding to one second in the jump mode, and a rearming of the flexible guide (4) is carried out to start a successive stop mode with blocking of the going train. 6. Watch with mechanical movement (1) according to claim 5, characterized in that the first direction of rotation is a rotation in the counter-clockwise direction, while the second direction of rotation is a rotation in the direction clock hands. 7. Mechanical movement watch (1) according to claim 3, characterized in that the blocking element (7) is a whip (7), which comprises a first blocking rod part and a second blocking rod part with respect to its center which includes the axial blocking pinion (8) in such a way as to perform a half-turn in the jump mode before being blocked by the pallet (3a) of the rake (3) in the stop. 8. Watch with a mechanical movement (1) according to one of the preceding claims, characterized in that the fixed second wheel SFA (2) comprises peripheral toothing meshing with an escapement toothed pinion (12) coaxial with said mobile d escapement (11), a middle wheel (10) of the going train having peripheral toothing meshing with the axial second gear pinion (5) coaxial with said second wheel (2), an intermediate wheel (9) comprising also said going train comprising an intermediate axial toothed pinion (19) meshing with a toothing on the periphery of the middle wheel (10), said intermediate wheel (9) comprising a toothing on the periphery for meshing with said axial locking pinion (8) secured to said rotary blocking element (7). 9. Mechanical movement watch (1) according to claim 1, characterized in that the escapement mechanism is a Swiss lever escapement mechanism (13) of the mechanical movement, and in that said oscillator (14) is a balance-spring intended to be set in oscillation by a drive generated by a barrel spring constituting said source of energy in normal operating mode. 10. Watch with mechanical movement (1) according to claim 3, characterized in that the pallet (3a) of the rake (3) is made of a hard material, such as ruby, to reduce friction. 11. Mechanical movement watch (1) according to claim 1, characterized in that the flexible guide (4) comprises at least one fixed portion (4b), at least one movable portion (4c), and elastic blades (4a) connecting the fixed portion (4b) to the movable portion (4c). 12. Mechanical movement watch (1) according to claim 11, characterized in that the fixed portion (4b) is arranged to be fixed on a support of the movement, and in that the movable portion (4c) is arranged to be fixed to the SFA fixed seconds wheel (2). 13. Watch with a mechanical movement (1) according to claim 12, characterized in that the fixed portion (4b) comprises at least one opening (16) for the passage of a fixing means on the support of the movement, and in that that the mobile portion (4c) comprises at least one opening (17) for fixing the SFA fixed second wheel (2). 14. Mechanical movement watch (1) according to claim 13, characterized in that the fixed portion (4b) and the movable portion (4c) of the flexible guide (4) are both connected by several elastic blades (4a), preferably two elastic blades (4a) in the shape of a V, in that each of the elastic blades (4a) connects a peripheral end of each fixed portion (4b) and each movable portion (4c), in that two through openings (16 ) in the fixed portion (4b) are provided for attachment to a movement support, and in that two through openings (17) in the movable portion (4c) are provided for attachment to the SFA fixed second wheel (2 ). 15. Mechanical movement watch (1) according to claim 13, characterized in that a fixed portion (4b) is provided, while two movable portions (4c) are each arranged in a respective V-shaped housing of the portion fixed and in opposition symmetrically with respect to each other, in that the two movable portions (4c) are further connected by several elastic strips (4a) in connection with an intermediate portion close to the axial opening (25 ) of the flexible guide (4), in that two through-openings (16) are made in the fixed portion (4b) and in that one through-opening (17) per movable portion (4c) is made. 16. Watch with mechanical movement (1) according to claim 11, characterized in that the flexible guide (4) comprises a fixed portion (4b) arranged in a housing with a large V-shaped opening of the movable portion (4c), which comprises an axial opening (25), in that two through openings (16) are provided in the fixed portion (4b) and arranged on the same line with the axial opening (25), in that two through openings (17 ) are provided in the movable portion (4c) and arranged practically on the same line with the axial opening (25), in that four successive elastic strips (4a) connect a first inner side of the movable portion (4c) to a first inner side of the fixed portion (4b), where two first elastic blades (4a) from the movable portion (4c) are connected by a first intermediate central portion, while two second elastic blades (4a) from the fixed portion (4c ) are connected by a second intermediate central portion e, the two intermediate strips being connected by a first intermediate peripheral portion, in that four successive elastic strips (4a) connect a second interior side of the movable portion (4c) to a second interior side of the fixed portion (4b), where two first elastic blades (4a) from the movable portion (4c) are connected by the same first intermediate central portion, while two second elastic blades 4a from the fixed portion (4c) are connected by the same second intermediate central portion, the two intermediate blades being connected by a second intermediate peripheral portion. 17. Watch with mechanical movement (1) according to claim 11, characterized in that the fixed portion (4b) is arranged in a housing with a large V-shaped opening of the movable portion (4c), which comprises an axial opening ( 25), which is coaxial with the axis of the second pinion (5), in that two through openings (16) are provided in the fixed portion (4b) and arranged on the same line with the axial opening (25) , in that two through openings (17) are provided in the movable portion (4c) and arranged practically on the same line with the axial opening (25), in that five successive elastic blades (4a) connect a first inner side from the movable portion (4c) to a first inner side of the fixed portion (4b), in that a first elastic blade (4a) from the movable portion (4c) is connected to a first intermediate central portion, in that 'a second elastic blade (4a) from the first intermediate central portion is connected to a first e intermediate peripheral portion, in that a third elastic blade (4a) from the first intermediate peripheral portion is connected to a second intermediate central portion, in that a fourth elastic blade (4a) from the second intermediate central portion is connected to a second intermediate peripheral portion, in that a fifth elastic blade from the second intermediate peripheral portion is connected to a second inner side of the fixed portion (4a), in that five successive elastic blades (4a) connect a second side interior of the mobile portion (4c) to a second interior side of the fixed portion (4b), in that a first elastic blade (4a) from the mobile portion (4c) is connected to the same first intermediate central portion, in that a second elastic blade (4a) from the same first intermediate central portion is connected to the same first intermediate peripheral portion, in that a third elastic blade (4a) of then the first intermediate peripheral portion is connected to the same second intermediate central portion, in that a fourth elastic blade (4a) from the second intermediate central portion is connected to the same second intermediate peripheral portion. A fifth elastic blade from the same second intermediate peripheral portion is connected to a first inner side of the fixed portion (4b). 18. Watch with a mechanical movement (1) according to claim 1, for which the watch comprises a traditional mechanical movement without a tourbillon, characterized in that the fixed second wheel SFA (2) pivots on the second pinion (5), which is connected by one or two rotary satellites (51, 52) to a first ring gear (53) forming a differential gear not integral with the SFA fixed second wheel (2), in that the flexible guide (4) with elastic blades ( 4a) crossed is connected to a stop member (3), which is connected to a second crown (32) mounted on the fixed second wheel SFA (2) and coaxial with the axis of rotation, in that the guide flexible (4) comprises a fixed base portion fixed by a fixing means (44) on a watch movement support, and a mobile portion which can be directly the second crown (32) linked to the stopper member ( 3), in that the elastic blades (4a) crossed are fixed at one of their ends to the second crown (32).