EP3882712A1 - Mechanical timepiece movement provided with an escapement including an elastically deformable anchor - Google Patents

Abstract

The watch movement comprises a mechanical resonator (2) and an escapement (12) comprising an escape wheel (16), which has a plurality of teeth (42), and an anchor (14) formed of a rod (20). and two arms (24, 26) respectively having two mechanical paddles (28, 29) capable of coming into contact, when the anchor undergoes a reciprocating movement, with any of the teeth according to the angular position of the wheel. exhaust. To prevent damage to the escapement during tilting of the anchor while the escape wheel is positioned in an unfavorable angular position, the anchor is arranged so as to be able, during said tilting of this anchor, to flex. by undergoing an elastic deformation. The anchor has an elastic capacity, between each of the two mechanical paddles and a fork (18) of the anchor, allowing it to elastically absorb, during said elastic deformation, a maximum mechanical energy that the mechanical resonator can have during the normal operation of the watch movement.

Description

Technical area

The invention relates to watch movements comprising an escapement provided with an anchor cooperating, on the one hand, with an escape wheel and, on the other hand, with a mechanical resonator, the anchor having a different axis of rotation. that of the mechanical resonator.

In particular, the invention relates to a watch movement provided with an escapement comprising a magnetic coupling system between an escape wheel and an anchor. As in the case of a Swiss anchor, the anchor exhibits a reciprocating movement which is synchronous with the periodic movement of the mechanical resonator, but different. By magnetic escapement, one understands an escapement provided with magnets arranged partly on the anchor and partly on the escape wheel so as to generate a magnetic coupling between the anchor and the escape wheel.

Technological background

The Swiss lever escapement has been known for a very long time. In normal operation, the teeth of the escape wheel cooperate with two vanes of the anchor in a determined manner allowing a step-by-step rotation of the escape wheel which is synchronous with the oscillation of the mechanical resonator, namely usually a sprung balance. When the force torque supplied to the escape wheel decreases as the barrel spring relaxes, the sustaining pulses generated by the escapement and transmitted to the resonator gradually decrease in intensity so that when the wheel dips. The exhaust ends up stopping while said torque force becomes less than a limit value, the energy stored in the resonator is relatively low. So the risk that a pallet or a tooth of the escape wheel is damaged during a possible terminal impact between a pallet and a tooth, depending on the angular stop position of the escape wheel, is relatively low although not excluded . The situation is more problematic in the case of a watch movement provided with a constant force drive system for the escapement wheel, since the resonator retains substantially the same mechanical energy throughout the operation of the escapement until 'when the escape wheel and its drive are stopped. The risk of an accidental event at the end of the watch movement is therefore increased.

Summary of the invention

The inventor has observed that the problem indicated above becomes a major drawback in the case of a watch movement comprising a hybrid, magnetic and mechanical escapement. Indeed, it has been observed that the risk of a terminal impact between the anchor and the escape wheel increases sharply in the case of a hybrid escapement, namely an escapement provided with a magnetic coupling system between anchor and escape wheel, with magnetic potential energy ramps to accumulate potential magnetic energy in the escapement with each step of the stepping rotation of the front escape wheel to generate a magnetic pulse at the end of the step while this escape wheel is stationary, and the escape wheel of which comprises teeth provided to cooperate with mechanical paddles of the anchor in at least one phase of operation of the escapement (for example when starting and / or during normal operation of the watch movement to absorb at each step the kinetic energy of the escape wheel and possibly define angular stop positions for the escape wheel , as will be explained in the detailed description of the invention). Indeed, this type of escape combines the risks of stopping the escape wheel in a position angular at risk while the resonator still has nominal mechanical energy. First, the sustain pulses are magnetic pulses having a constant value as long as the force torque supplied to the escape wheel is greater than or equal to a certain lower limit. Then, as soon as said torque force is below this lower limit, the escape wheel can no longer correctly climb the next ramp of magnetic potential energy, so that the escape wheel will not stop in a next angular stop position normal, but substantially at the bottom of or along a ramp of magnetic potential energy. Therefore, as the mechanical resonator oscillates normally during such an event since it has previously received magnetic pulses of substantially constant intensity (nominal intensity), if a mechanical vane appears in front of a tooth during the next tilting anchor, a strong impact may occur and damage the escape wheel or the anchor, or even the mechanical resonator. This increased technical problem, brought to light by the inventor, therefore requires an appropriate technical solution.

In general, the present invention relates to a watch movement comprising a mechanical resonator, in particular a sprung balance, and an escapement, associated with this mechanical resonator, which is formed by an escape wheel comprising a plurality of projecting parts, in particular teeth, and by an anchor provided with a fork, intended to cooperate with a pin of the mechanical resonator, and two mechanical paddles which are intended to cooperate with the plurality of teeth at least in a certain phase of operation of the watch movement. This watch movement is arranged so that, when the anchor is tilted from a first of its two rest positions towards the second rest position while the escape wheel is positioned in any angular position θ of a plurality of ranges of angular positions corresponding respectively to the plurality of protruding parts, one of the two mechanical vanes of the anchor abuts against one of these protruding parts before this anchor can reach the angular position of release of the ankle, integral with the mechanical resonator, on the side of the second rest position. According to the invention, the anchor is arranged so as to be able, during said tilting of the anchor, to bend, in a general plane of the anchor parallel to its fork, undergoing an elastic deformation under the action of a force exerted by the pin of the mechanical resonator, engaged in the fork, on one of the two horns of this fork while said mechanical pallet abuts against said projecting part and the mechanical resonator is braked by the anchor. In addition, this anchor has an elastic capacity, between each of the two mechanical paddles and the fork, allowing it to absorb in the form of elastic energy, during said elastic deformation, a maximum mechanical energy that the mechanical resonator can have during the normal operation of the watch movement.

In a main embodiment, the escapement comprises a magnetic system magnetically coupling the escapement wheel and the anchor, this magnetic system being arranged so as to generate, during the normal operation of the watch movement, magnetic pulses having an energy. substantially constant to maintain an oscillation of the mechanical resonator via an interaction between the pin of this mechanical resonator and the fork of the anchor.

In a particular variant, said magnetic pulses are generated at the level of two mechanical paddles which respectively support two magnets forming two magnetic paddles. The anchor is arranged so as to be able, during normal operation of the watch movement, to substantially transmit a torque of magnetic force generated by each of the magnetic pulses to its fork in order to maintain an oscillation of the mechanical resonator.

Brief description of the figures

The invention will be described below in more detail with the aid of the accompanying drawings, given by way of non-limiting examples, in which the Figures 1A to 1F partially show a watch movement, according to a main embodiment of the invention, shown in successive positions following a stop of the escape wheel in a particular angular position.

Detailed description of the invention

With the aid of the appended figures, a main embodiment of a watch movement according to the invention will be described below, which is of the mechanical type and comprises a mechanical resonator 2, of which only the axis 4, the small plate 6 having a notch and the pin 10 have been shown. The watch movement comprises an escapement 12 which is associated with the mechanical resonator, the small plate and the pin of which are elements forming this escapement. The escapement 12 further comprises an escape wheel 16 and an anchor 14 which is a member separate from the mechanical resonator and whose single axis of rotation is different from that of this mechanical resonator.

The anchor 14 is formed, on the one hand, of a rod 20 terminated by a fork 18, comprising two horns 19a and 19b, and by a dart 8 and, on the other hand, of two arms 24 and 26 whose free ends respectively form two mechanical paddles 28 and 29. The two mechanical paddles respectively support two magnets 30 and 32 which form two magnetic paddles of the anchor 14. The mechanical resonator 2 is coupled to the anchor so that, when the resonator mechanical oscillates normally, this anchor undergoes a reciprocating movement, synchronized with the oscillation of the mechanical resonator, between two rest positions, defined by two limiting pins 21 and 22, in which the anchor remains alternately during successive time intervals.

The escape wheel 16 comprises a periodic magnetized structure 36 which is arranged on a disc 34, preferably made of non-magnetic material (not conducting magnetic fields so as not to make the escape wheel sensitive to external magnetic fields which could exert a significant torque on this escape wheel if this disc were made of ferromagnetic material). The structure 36 has magnetized portions 38, generally in the arc of a circle, which define increasing ramps of magnetic potential energy for the two magnetic vanes 30 and 32, which each have an axial magnetization with a polarity opposite to that of the magnetization. axial of the periodic magnetized structure so as to generate magnetic repulsion between the magnetic vanes and the magnetized structure. Each magnetized portion has an increasing monotonic width. In particular, the width of the magnetized portions 38 increases, over the whole of their useful length, in a linear manner as a function of the angle at the center. According to an advantageous variant, the periodic magnetized structure 36 is arranged so that its outer periphery is circular, the magnetized portions in the arc of a circle of this magnetized structure having the same configuration and being arranged circularly around the axis of rotation of the wheel. exhaust.

In general, each increasing ramp of magnetic potential energy is provided so that each of the two magnetic paddles can climb it when the anchor is in a given rest position, among its two rest positions, and that a couple of force supplied to the escape wheel is approximately equal to a nominal force torque (in the case of a mechanical movement provided with a constant force system for driving the escape wheel) or within a range of values provided to ensure the normal operation of the watch movement (case of a conventional mechanical movement having a variable force torque applied to the escape wheel depending on the level of winding of the barrel or barrels if several are provided in series). The increasing ramps of magnetic potential energy are climbed, when the anchor undergoes a reciprocating movement between its two rest positions and when the force torque supplied to the escape wheel is equal to said nominal force torque or within the range of values provided for this force torque in normal operation, successively by each of the first and second magnetic paddles while the anchor is respectively in its first and second rest positions, and alternately by these first and second magnetic paddles during the reciprocating movement of the anchor. The two magnetic paddles and the increasing ramps of magnetic potential energy are arranged so that the anchor can undergo a pulse of magnetic force in the direction of its movement, after any of the two magnetic paddles has climbed any of said ramps. increasing magnetic potential energy, when the anchor swings from the rest position corresponding to this any ramp of magnetic potential energy to its other rest position.

The periodic magnetized structure further defines for each of the two magnetic paddles magnetic barriers 46 which are located respectively following the increasing ramps of magnetic potential energy defined by the magnetized portions 38, these magnetic barriers being formed in particular by magnetized areas 46 of the structure 36, the radial dimension of which is substantially equal to or greater than the longitudinal dimension of each of the two magnets 30 and 32 forming the magnetic vanes of the anchor. In another variant, the magnetic barriers are not provided, the magnetized portions 38 then extending partially under the projecting parts 42 described below.

The escape wheel further comprises protrusions which are respectively associated with increasing ramps of magnetic potential energy. These projecting parts are formed by teeth 42 extending radially from a plate 40 which is integral with the escape wheel and situated above the disc 34 carrying the magnetized structure 36. These teeth are located respectively after the magnetized portions 38, on the side of their widest end, and are partially superimposed on the corresponding magnetized areas 46. The teeth and mechanical paddles are formed by a non-magnetic material. Preferably, the plate 40 is also formed by a non-magnetic material and it is integrally formed with the teeth.

In the advantageous variant shown, the teeth 42 extend in a general plane in which also extend the two mechanical vanes 28, 29 of the anchor. The two magnets 30, 32 are respectively supported by the two mechanical paddles and are also located in said general plane. The figures only show a lower magnet structure, located below the general plane. However, in an advantageous variant, the escape wheel further comprises an upper magnetized structure, of the same configuration as the lower magnetized structure and supported by an upper disc, preferably formed of a non-magnetic material. The lower and upper magnet structures together form the periodic magnet structure. They have the same magnetic polarity, opposite to that of the two magnets of the anchor, and are arranged on either side of the geometric plane in which these two magnets forming the two magnetic vanes are located, preferably at the same distance.

Before describing the object of the present invention in more detail, particular characteristics of the exhaust of the main embodiment will be described which make it possible, on the one hand, to improve its behavior in normal operation (i.e. - say during stable operation, occurring after a starting phase, with a force torque M _RE supplied to the escape wheel which is substantially equal to a nominal force torque or within a range of values provided to ensure the normal functioning of the watch movement, in particular a correct step-by-step rotation of the escape wheel) and, on the other hand, to obtain a auto-start of the assembly formed by the exhaust and the mechanical resonator.

First, the anchor 14 and the escape wheel 16 are arranged so that, in normal operation, one of the teeth 42 of the escape wheel experiences at least one impact on one or the other of the two mechanical paddles after the corresponding magnetic paddle has climbed any one of the increasing ramps of magnetic potential energy following a tilting of the anchor. This shock occurs so as to at least partially dissipate a kinetic energy of the escape wheel acquired following said tilting. The teeth of the escape wheel are designed to be able to absorb the kinetic energy of this escape wheel, with each step of the escape wheel, after an accumulation of magnetic potential energy in the escapement for a subsequent sustain pulse of the mechanical resonator, and thus to limit a terminal oscillation during each step of its step-by-step rotation.

In a preferred variant, in normal operation and once the escape wheel has momentarily stopped, a tooth 42 presses against a mechanical stop of the anchor formed by one or the other of the two mechanical vanes. The escapement is therefore a hybrid escapement, that is to say magnetic and mechanical. Thus, for a conventional movement, it is expected, in normal operation and for the entire range of values PV _M of the force torque M _RE , for the escape wheel to stop momentarily, after at least a first impact of a any of its teeth against any of the two mechanical paddles and before a subsequent tilting of the anchor, to an angular stop position in which any tooth presses against any mechanical paddle. Each angular stop position is thus defined by a tooth bearing against a mechanical pallet.

Then, the teeth 42 and the mechanical paddles 28, 29 are arranged so that, during a new winding of the barrel spring following a stop of the watch movement and allowing the escape wheel 16 to resume rotating in the intended direction of rotation, at least one of the two mechanical paddles 28, 29 contacts a tooth 42 of the escape wheel, which are configured so that the escape wheel can provide the anchor 14 a couple of starting mechanical force and therefore a starting mechanical impulse. Thus, efficient and rapid self-starting of the assembly formed of the escapement 12 and of the mechanical resonator 2, and therefore of the mechanical watch movement, is made possible. In particular, the escape wheel subjected to said starting torque is not stopped by the contact between the tooth and the mechanical pallet concerned, but the tooth can transmit at least most of the starting torque to the anchor.

In the advantageous variant shown in the figures, each of the teeth 42 has, in a polar coordinate system of the escape wheel 16 which is centered on its axis of rotation, a first inclined surface which is inclined so that each of the first and second mechanical paddles 28, 29 can, in a starting phase, slide on this first inclined surface while the escape wheel passes through a corresponding range of angular positions θ. By “inclined surface” in a polar coordinate system, we understand a surface which is neither radial nor tangential. In addition, each of the two mechanical pallets of the anchor has, in the polar coordinate system associated with the escape wheel, a second inclined surface when the pallet considered is in contact with one of the teeth 42 of the escape wheel. . The second inclined surface is configured so that each of the teeth 42 can, in a starting phase, slide on this second inclined surface when the escape wheel passes through a range of angular positions θ which corresponds to a contact zone between the tooth and the mechanical pallet considered.

• un seul axe de pivotement 50 qui est centré sur un unique axe géométrique de rotation prévu pour l'ancre ;
• une partie de liaison rigide 25 à laquelle est fixé l'axe de pivotement, lequel traverse cette partie de liaison et présente classiquement à ses deux extrémités deux pivots guidés en rotation par deux pierres percées ;
• deux bras 24 et 26 liés, à leurs premières extrémités, à la partie de liaison 25 et présentant respectivement, à leurs secondes extrémités, les deux palettes mécaniques 28, 29 qui sont susceptibles d'entrer en contact, au moins lors d'une certaine phase de fonctionnement de l'échappement, avec une quelconque partie saillante / dent parmi la pluralité de parties saillantes / dents 42 de la roue d'échappement et qui sont agencées pour pouvoir coopérer avec ces parties saillantes, comme exposé précédemment ;
• une fourchette 18 ayant classiquement deux cornes 19a, 19b et agencée pour coopérer avec le résonateur mécanique 2 via sa cheville 10 qui est solidaire de l'axe central 4 de ce résonateur mécanique ; et
• une baguette 20 liée à sa première extrémité à la partie de liaison 25 et à sa seconde extrémité à la fourchette 18, cette baguette étant libre entre sa première extrémité et sa seconde extrémité.

Hereinafter, the specific object of the present invention will be described in more detail. In the context of the main embodiment described, the anchor 14 comprises:

• a single pivot axis 50 which is centered on a single geometric axis of rotation provided for the anchor;
• a rigid connection part 25 to which is fixed the pivot axis, which passes through this connection part and conventionally has at its two ends two pivots guided in rotation by two pierced stones;
• two arms 24 and 26 linked, at their first ends, to the connecting part 25 and having respectively, at their second ends, the two mechanical vanes 28, 29 which are liable to come into contact, at least during a certain operating phase of the escapement, with any protruding part / tooth among the plurality of protruding parts / teeth 42 of the escape wheel and which are arranged to be able to cooperate with these protruding parts, as explained above;
• a fork 18 conventionally having two horns 19a, 19b and arranged to cooperate with the mechanical resonator 2 via its pin 10 which is integral with the central axis 4 of this mechanical resonator; and
• a rod 20 linked at its first end to the connecting part 25 and at its second end to the fork 18, this rod being free between its first end and its second end.

In an advantageous variant, the connecting part, the rod and the two arms are formed by a single piece. In a preferred variant, the one-piece part is made of a metallic material.

The incorporation of teeth 42 to allow one and / or the other of the two functions described above, namely the damping of oscillations of the escape wheel during a step-by-step rotation of the latter in normal operation and / or a self-start of the assembly formed by the mechanical resonator and the escapement, in particular an escapement of the magnetic type, has the consequence that, during a tilting of the anchor 14 from a first of its two rest positions in the direction of the second rest position while the escape wheel 16 is positioned in any angular position θ of a plurality of ranges of angular positions corresponding respectively to the plurality of teeth, one of the two mechanical paddles abuts against one of these teeth before the anchor can reach the angular position of release of the ankle on the side of the second rest position, as shown in Figure 1B . By 'angular position of release' for the ankle of the mechanical resonator, in particular a sprung balance, one understands the angular position (on either side of a median position defining a zero angular position for the anchor) from which the ankle can be released, for one reason or another, from the fork, that is to say out of the cavity formed by the two horns 19a and 19b without abutting against one of these horns to bring the anchor precisely until this release position which occurs before the anchor reaches one or the other of its two rest positions. It will be noted that this last fact results from a usual safety angle provided to ensure that the ankle can correctly exit the fork without undergoing a shock or terminal friction which would cause it to lose energy at each alternation and would disturb the oscillation of the mechanical resonator.

As already indicated, when the barrel spring relaxes, there comes a time when the watch movement ceases to function normally since the torque force that the barrel can provide to the gear train and the escape wheel becomes insufficient to ensure a such normal operation. At a certain point in time, as shown in Figure 1A , the escape wheel 16 finally stops rotating step-by-step and comes to rest in a certain angular position θ, but the mechanical resonator is at this instant still oscillating and may even have a substantially nominal mechanical energy and therefore relatively large, especially in the case of an exhaust 12 fitted with the system magnetic previously described. As mentioned in the previous paragraph, in particular in the case of an escapement 12 provided with the magnetic system, described above, to provide magnetic sustaining pulses, the escape wheel 16 can stop in any angular position θ d 'a plurality of ranges of angular positions, corresponding respectively to the plurality of teeth 42, for which one of the two mechanical paddles then abuts against one of these teeth before the anchor can reach the angular position of release of the pin, as shown in Figure 1B . The Figure 1B shows a particularly unfavorable case where an end portion 48 of the mechanical pallet 29 is subjected to an impact on the top of the head 43 of a tooth 42 against which this mechanical pallet abuts. In such a case, the total force exerted by the anchor on the tooth 42 concerned is substantially radial, in a polar coordinate system associated with the escape wheel, so that the escape wheel is not driven in rotation and suffers a strong shock.

It will be noted that the significant shock in question does not relate only to the instant at which the mechanical pallet and the tooth come into contact, but it is about an impulse of radial force which has a certain duration since this shock takes place while the pin of the oscillating resonator is inserted between the two horns 19a and 19b of the fork 18 and a magnetic pulse is supplied to the anchor. During the aforementioned shock, the radial force impulse has several components, firstly a component arising from the inertia of the moving anchor 14 which is stopped; secondly, a main component due to the mechanical energy stored in the oscillating mechanical resonator 2 which is stopped in its oscillation while its kinetic energy is almost maximum, via the coupling between the fork 18 and the pin 10; and thirdly a magnetic component resulting from the fact that the shock occurs while a magnetic pulse is supplied to the anchor (represented by an arrow at the Figure 1B ). Thus, it is probable that, when the end part 48 of the mechanical pallet 29 comes into contact with the head 43 of a tooth by abutting against this head, it is the anchor 14 which drives the mechanical resonator 2 by its horn 19b resting against the ankle 10, and only then, after a very short time interval, this ankle comes into abutment against the horn 19a of the fork and then undergoes a strong deceleration due to the premature stopping of the anchor in its tilting.

The more the braking of the mechanical resonator during the aforementioned shock is violent / has a strong intensity, the more the force F _RO exerted orthogonally on the horn 19a by the mechanical resonator, and by construction in a substantially tangential manner in a system of polar coordinates associated with the anchor, and the _{reaction force F FR} of the anchor, which slows down this resonator, are strong at the start of the shock (direction and direction of these forces are represented at the Figure 1C ). This poses a major problem, which is why the anchor 14 is arranged and configured to be able to prevent breakage or damage to itself, to a part of the escape wheel or even to a part of the mechanical resonator. during an event as shown to Figures 1A to 1C . To reduce the intensity of the force exerted by the resonator ankle during said large impact and therefore to avoid too violent instantaneous stress, a relatively long impact duration is provided to reduce the intensity of the deceleration. Then, the anchor is arranged to be able to elastically absorb the energy transmitted to it by the mechanical resonator stopped in its oscillation.

To this end, the anchor 14 is arranged so as to be able, during a tilting during which a shock described above occurs, to bend, in a general plane of the anchor parallel to the fork 18 (this is i.e. parallel, including coincident, to a general plane in which the horns of the fork extend), undergoing an elastic deformation under the action of a force F _RO exerted by the ankle 10, engaged in the fork , on one of its two horns 19a, 19b while the mechanical pallet concerned abuts against a tooth and that the mechanical resonator is braked by the anchor. In addition, this anchor has an elastic capacity, between each of the two mechanical paddles 18, respectively 29 and the fork 18, allowing it to elastically absorb, during said elastic deformation, a maximum mechanical energy that the mechanical resonator 2 can have during normal operation of the watch movement. It will be noted that this elastic capacity has a certain safety margin, because during the impact there is a certain dissipation of energy in particular at the level of the bearings of the escape wheel, of the mechanical resonator and of the anchor, and also in the various structures concerned, in particular the plate 40. Any breakage or deterioration of the escapement and of the mechanical resonator can thus be avoided. By elastic capacity 'is understood an elastic energy absorption capacity. Thanks to the characteristics of the anchor according to the invention, a sudden shock is avoided and a progressive dissipation of the mechanical energy of the mechanical resonator is allowed.

During a first impact between a mechanical pallet and a tooth of the escape wheel which occurs in the situation described above, the anchor undergoes an elastic deformation in order to be able to absorb the major part of the mechanical energy of the mechanical resonator, even if this mechanical energy corresponds to a nominal energy in normal operation of the watch movement. In the variant shown, it is the rod 20 which is designed to be able to substantially absorb said major part of the mechanical energy of the mechanical resonator. In the variant shown, the rod is designed to be curved, in particular with the general shape of a 'swan neck'. Other shapes are possible, also a substantially rectilinear rod. The curved configuration has an advantage in that it generally makes it possible to increase the length of the rod between the connecting part 25 and the fork 18. The 'gooseneck' shape allows a relatively long length of the rod, while having the fork relatively close to one of the two mechanical paddles. In a configuration with a relative positioning of the central axis 4 of the resonator as shown in the figures, those skilled in the art would connect the shortest fork with the arm 26, in the extension of the mechanical pallet 29. Thus, there would be virtually no absorption of kinetic energy from the oscillating resonator.

In the particular variant shown, a median geometric line of the anchor 14 between an end surface (terminal inclined plane) of each of the two mechanical pallets 28, 29 and the fork 18, has a total length, on the two sections 20a and 24a, respectively 20a and 26a which are defined by the mechanical pallet considered together with the corresponding arm 24 or 26 and by the rod 20 (see broken lines on Figure 1A ), which is at least twice the length of a straight line 52 between a point of the median geometric line 24a on the end surface closest to the fork and the middle of the bottom of a cavity defined by the two horns of this fork (see Figure 1B ). The elastic deformation capacity can be provided over the entire total length defined above or only over parts of this total length. Thus, in a first variant, the rod and the arms have an elastic deformation capacity, which may be different, while in a second variant, it is substantially the rod which has this elastic capacity. In a third variant, it is substantially the arms 24 and 26 which have an elastic capacity.

The anchor must therefore have an elastic deformation capacity and a capacity large enough to absorb elastic energy, these associated capacities being a function of several parameters that a person skilled in the art will be able to select and determine in order to obtain the desired values. As mentioned, the shape can play a role, as well as the length of the material path between the mechanical paddles and the fork. Other parameters also play a role, including the material selected and the various cross sections. Note that the minimum cross section of the anchor also plays a role, which should not be too much small by promoting the flexibility of a portion of the anchor to the detriment of elastic energy absorption. In the main embodiment described, magnetic pulses for maintaining the oscillation of the mechanical resonator are generated at the level of the two mechanical vanes 28, 29 which respectively support two magnets 30, 32 forming two magnetic vanes. Thus, the anchor 14 is arranged so as to be able, during normal operation of the watch movement and therefore of the escapement, to substantially transmit a torque of magnetic force, generated by each of the magnetic pulses, to its fork in order to maintain a oscillation of the mechanical resonator. It will be noted that this condition can easily be implemented owing to the fact that the quantity of energy in a magnetic pulse is much less than the mechanical energy possessed by the mechanical resonator 2 in normal operation.

Finally, we will describe using the Figures 1B to 1F a succession of events occurring at various specific instants for a hypothetical case where the escape wheel 16 stops in the unfavorable position shown in Figures 1A and remains in this position until the mechanical resonator 2 stops. Figure 1B , as indicated above, the pin 10, after having entered the fork 18, abuts against the horn 19a while the anchor is stopped in its movement from the rest position where the fork is resting against the pin 22 towards the position rest where this fork is provided to rest against the pin 21. When the impact between the mechanical pallet and the tooth begins, the angle at the center of rotation of the anchor between the horn 19b and the pin 22 has a certain value α1. The resonator having at this instant a nominal and therefore significant mechanical energy, essentially in the form of kinetic energy, it then presses against the horn 19a by exerting a _{decreasing force F RO} while the anchor, here especially the rod 20, flexes in absorbing most of the kinetic energy of the resonator in the form of elastic energy. The angle defined above therefore increases, as shown in Figure 1C where its value a2 is greater than the value a1, for example approximately one value double, the Figure 1C showing a configuration when the mechanical resonator has lost most of its speed (and therefore of its kinetic energy). Then, imperatively before the ankle 10 reaches the clearance angle which would allow it to come out of the fork, the mechanical resonator passes through an angular stop position and a premature reversal of the direction of its movement, as shown in Figure 1D where the resonator rotates counterclockwise whereas it previously rotated clockwise. Under the action of the anchor via the horn 19a, the resonator recovers the major part of the elastic energy stored in the anchor and it thus undergoes an acceleration which leaves it a certain amplitude of oscillation, although less than that. which he presented before the shock.

By disengaging from the fork 18, propelled by the rod 20 of the anchor 14, the pin 10 can then come out of the fork, as shown in Figure 1E . Then, during a subsequent alternation, a new sequence, similar to that presented with reference to the Figures 1A to 1E , intervenes again. However, the mechanical resonator 2 having lost energy during the first shock, it will then generate less bending of the anchor 14. The oscillation of the mechanical resonator is thus quickly damped and it ends up stopping, as shown in the Figure 1F , without having damaged the mechanical movement, in particular the hybrid escapement.

Claims (10)

Watch movement comprising a mechanical resonator (2) and an escapement (12) which is associated with this mechanical resonator, the escapement comprising an escape wheel (16), which has a plurality of protrusions (42), and an anchor (14) which is separate from the mechanical resonator and which has a single geometric axis of rotation; the mechanical resonator being coupled to the anchor so that, when this mechanical resonator exhibits a sustained oscillation, the anchor undergoes an alternating movement between two rest positions in which the anchor remains alternately during successive time intervals; in which the anchor comprises: - a single pivot axis (50) centered on said single geometric axis of rotation, - a rigid connection part (25) to which is fixed the pivot axis, - two arms (24, 26) linked, at their first ends, to the connecting part and having respectively, at their second ends, two mechanical paddles (28, 29) which are each capable of coming into contact with any part protruding from among the plurality of protruding parts of the escape wheel and which are arranged to cooperate with these protruding parts at least in a starting phase or during normal operation of the watch movement, - a fork (18) having two horns (19a, 19b) and arranged to cooperate with the mechanical resonator via a pin (10) integral with an axis (4) of this mechanical resonator, and - a rod (20) linked at its first end to said connecting part (25) and at its second end to the fork, this rod being free between its first end and its second end; wherein, upon tilting of the anchor from a first of its two rest positions towards the second rest position while the escape wheel is positioned in any position angular θ of a plurality of ranges of angular positions corresponding respectively to said plurality of protrusions, one of the two mechanical paddles abuts against one of these protrusions before the anchor can reach an angular position of release of the ankle on the side from the second rest position; in which the anchor is arranged so as to be able, during said tilting of the anchor, to bend, in a general plane of the anchor parallel to the fork, undergoing an elastic deformation under the action of a force exerted by the pin, engaged in the fork, on one of the two horns of this fork while said mechanical pallet abuts against said projecting part and the mechanical resonator is braked by the anchor; this anchor having an elastic capacity, between each of the two mechanical paddles and the fork, allowing it to elastically absorb, during said elastic deformation, a maximum mechanical energy that the mechanical resonator can have during normal operation of the watch movement. A watch movement according to claim 1, wherein the escapement or an escape wheel drive mechanism is arranged so that, in normal operation of the watch movement, the escape wheel (16) provides the anchor pulses for sustaining an oscillation of the mechanical resonator (2) which have a substantially constant energy as long as the watch movement is operating normally. Watch movement according to Claim 2, in which the escapement comprises a magnetic system (30, 32, 36) magnetically coupling the escapement wheel and the anchor, this magnetic system being arranged so as to generate, during normal operation of the watch movement, magnetic pulses which form said constant energy sustain pulses. Watch movement according to claim 3, wherein the protrusions (42) are arranged so as to allow absorption. of kinetic energy of the escape wheel (16) by shocks, between these projecting parts alternately with the two mechanical paddles, respectively at the end of successive steps of a step-by-step rotation of the escape wheel during normal operation of the watch movement. Watch movement according to claim 3 or 4, in which the protrusions (42) are arranged so as to allow a self-start of the assembly formed of the mechanical resonator (2) and of the escapement (12) when the spring of barrel is rearmed, following a stop of the watch movement, and the escape wheel is again driven in rotation. Watch movement according to any one of claims 3 to 5, in which said magnetic pulses are generated at the level of two mechanical paddles (28, 29) which respectively support two magnets (30, 32) forming two magnetic paddles; and in which the anchor is arranged so as to be able, during the normal operation of the watch movement, to substantially transmit a torque of magnetic force generated by each of the magnetic pulses to its fork (18) in order to maintain an oscillation of the mechanical resonator. Watch movement according to any one of the preceding claims, in which said strip (20) is curved, in particular with the general shape of a 'swan neck'. Watch movement according to any one of the preceding claims, in which a median geometric line of the anchor, between an end surface of each of the two mechanical paddles and the fork, has a total length, over two sections (24a, 20a; 26a , 20a) defined respectively by the considered mechanical pallet (28, respectively 29) together with the corresponding arm (24; 26) and by the rod (20), which is at least twice the length of a straight line (52 ) between a point of the geometric median line on said end surface and the middle of the bottom of a cavity defined by the two horns of the fork. Watch movement according to one of the preceding claims, in which the connecting part (25), the rod (20) and the two arms (24, 26) are formed by a single piece. Watch movement according to the preceding claim, in which said one-piece part is made of a metallic material.

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