EP3599514A1 - Exhaust mechanism having bistable and monostable springs - Google Patents

Abstract

The present invention relates to a timepiece escapement mechanism (1) comprising a bistable elastic blade (L) working in buckling around a median point of inflection between two anchor points (A, B), a winding rocker (3) of said bistable elastic blade (L), and an exhaust mobile (4, 5) arranged to sequentially transmit a drive torque to the arm lever (3) so as to rotate said lever winding alternately in a clockwise and counterclockwise direction, and a trigger rocker (2) secured to the bistable elastic blade (L) at its median inflection point and arranged to cooperate with a regulating member (0) oscillating by said clockwork movement at each alternation thereof so as to transmit an impulse to it following a relaxation of the elastic blade (L). Typically, the mechanism of the invention also comprises a monostable elastic member (10c) for compensating for a variation in the driving torque of the winding lever (3) by the exhaust mobile (4, 5) as a function of the direction of rotation of said winding lever (3).

Description

Technical area

The present invention relates to the field of watchmaking and relates, more particularly, to a bistable spring escape mechanism formed by a blade working in buckling around a central point of inflection in cooperation with a winding rocker. and an expansion lever for transmitting pulses of mechanical energy from a motor source to an oscillating regulator of a timepiece.

State of the art

Such escape mechanisms, known as constant force, have been known for almost twenty years and the publication of the patent application WO 99/64936 . However, they only found a practical implementation a decade ago with the development and mastery of deep silicon etching technology for watchmaking, allowing the realization in a monolithic form of a blade flamed around a central point of inflection between two anchor points on a frame, the anchor points and the central point of inflection of the flamed blade being perfectly aligned. These first practical implementations have been described in particular in the requests WO 2009/118310 or CH 705674 of the plaintiff.

More recently, various improvements have also been made to these exhaust mechanisms to improve their performance and operating reliability, as for example described in the documents. CH 710925 and WO 2018/015146 , also on behalf of the Applicant.

Always with the aim of improving the efficiency of such an exhaust with a bistable leaf spring, the Demand WO 2018/002773 proposed an escape mechanism comprising a bistable leaf spring and a single escape mobile to drive a winding rocker during the winding phases, the escape mobile comprising a coaxial winding member arranged for cooperate with the winding rocker like a gear to rotate the winding rocker alternately in opposite directions.

1. 1) Lorsque la bascule d'armage tourne dans le sens inverse du mobile d'armage, le petit bras de levier est insuffisant pour vaincre la force de rappel du ressort bistable et l'amener dans son état métastable ; le mécanisme d'échappement se trouve alors bloqué, à l'arrêt, et de fait l'organe régulateur associé également, de même que le mouvement les comportant.
2. 2) Si le petit bras de levier permet malgré tout de vaincre la force de rappel du ressort bistable, le couple agissant sur la bascule d'armage est alors trop fort lorsque celle-ci tourne dans le même sens que le mobile d'armage ; il en résulte immanquablement des pertes d'énergie par chocs lors du verrouillage du mécanisme, après que le ressort d'échappement a atteint son état métastable, qui se traduisent par un mauvais rendement de l'échappement.

Such a mechanism is particularly attractive at first glance because it makes it possible to reduce a priori in a singular way the overall bulk of the mechanism by the use of a single exhaust mobile, which more is arranged coaxially with a mobile of armament as well as a locking mobile which respectively cooperates substantially punctually by pointed teeth, that is to say with reduced friction, with an armament path arranged in a ring integral with the arm action rocker on the other hand and with the trigger. However, in practical terms of implementation, this solution proves to be otherwise impractical, at least functionally ineffective. In fact, in the configuration presented in this patent application, the escape mechanism can only function at best when the winding lever and the winding mobile pivot in the same direction of rotation around their respective axis of rotation for arm the bistable blade, which corresponds according to the convention presented to a clockwise direction of rotation. On the other hand, during a winding of the spring requiring a pivoting of the winding lever in the opposite direction to that of rotation of the winding mobile, therefore in a counterclockwise direction, the lever arm between the point of application of the force of a tooth of the armament mobile and the center of rotation of the arm lever is much lower than that provided for the clockwise rotation of the arm lever. This difference in leverage induces two types of faulty operation, namely:

1. 1) When the winding rocker rotates in the opposite direction to the winding mobile, the small lever arm is insufficient to overcome the return force of the bistable spring and bring it into its metastable state; the escape mechanism is then blocked, at a standstill, and in fact the associated regulating member also, as is the movement comprising them.
2. 2) If the small lever arm still allows the return force of the bistable spring to be overcome, the torque acting on the winding lever is then too strong when it rotates in the same direction as the mobile of armament; This inevitably results in energy losses by impact when the mechanism is locked, after the exhaust spring has reached its metastable state, which results in poor exhaust efficiency.

The aim of the present invention therefore consists in providing a solution to the functional defects of the structural approach of a bistable spring exhaust mechanism proposed in WO 2018/002773 while retaining the advantages of the latter in terms of efficiency and compactness of construction.

Disclosure of invention

This object is achieved by an escape mechanism whose characteristics are detailed in the claims.

• Une lame élastique au comportement bistable obtenu par flambage de ladite lame initialement droite après en avoir rapproché les deux extrémités encastrées de manière symétrique par rapport à un point de pivotement médian correspondant au point d'inflexion de ladite lame élastique une fois celle-ci contrainte en flambage entre ses deux points d'ancrage,
• une bascule d'armage de ladite lame élastique bistable, mobile en rotation et dont les mouvements sont tangentiellement solidaires de ladite lame élastique et ainsi liée cinématiquement selon une direction sensiblement perpendiculaire en deux points équidistantes du point d'inflexion médian et
• un mobile d'échappement apte à engrener avec un mobile du rouage de finissage d'un mouvement horloger, et agencé pour transmettre séquentiellement un couple d'entrainement à la bascule d'armage de manière à faire pivoter ladite bascule d'armage alternativement dans un sens horaire et un sens antihoraire pour faire passer ladite lame élastique bistable d'un état stable de repos à un état métastable d'armage, et
• une bascule de détente solidaire de la lame élastique en son point médian et agencée pour coopérer avec un organe régulateur oscillant d'un dit mouvement horloger à chaque alternance de celui-ci de manière à lui transmettre une impulsion consécutivement à une détente de la lame élastique bistable correspondant au passage d'un dit état d'armage à un dit état de repos symétrique à un état stable de repos précédent.

More particularly, the escape mechanism of the invention as defined in claim 1, comprising:

• An elastic blade with a bistable behavior obtained by buckling of said initially straight blade after having brought the two embedded ends thereof symmetrically with respect to a median pivot point corresponding to the point of inflection of said elastic blade once it has been constrained in buckling between its two anchor points,
• a rocking arm of said bistable elastic blade, mobile in rotation and whose movements are tangentially integral with said elastic blade and thus kinematically linked in a direction substantially perpendicular to two points equidistant from the point of median inflection and
• an escapement mobile able to mesh with a mobile of the clockwork of a clockwork movement, and arranged to sequentially transmit a drive torque to the arm lever so as to rotate said arm lever alternately in a clockwise and counterclockwise to pass said bistable elastic blade from a stable state of rest to a metastable state of winding, and
• a trigger rocker secured to the elastic blade at its midpoint and arranged to cooperate with a regulating organ oscillating with a said clockwork movement at each alternation thereof so as to transmit an impulse following a relaxation of the elastic blade bistable corresponding to the passage from a said arming state to a said symmetrical rest state to a previous stable state of rest.

The mechanism of the invention is further characterized in that it comprises a monostable elastic member dimensioned in such a way that it compensates for the variation in the driving torque of the winding lever by the exhaust mobile depending on the direction of rotation of said winding lever.

The mechanism of the invention thus makes it possible, by virtue of the provision of a monostable elastic member for compensating for bearing, the variations in winding torque applied to the winding rocker by the escape wheel according to the direction of rotation of this last in a configuration as proposed in WO 2018/002773 , and thus, by adapting the return force of the monostable elastic compensation member according to the dimensions of the other elements of the exhaust mechanism and the characteristics of the bistable elastic blade, to guarantee the alternating tilting of the winding lever perfectly balanced, without unnecessary energy loss or risk of blockage, with increased efficiency compared to similar exhaust mechanisms. This makes the exhaust mechanism more reliable and reliable.

In one embodiment of the invention, the monostable elastic compensation member is coupled to the winding lever and arranged to exert on the latter a restoring torque in a single direction of rotation.

In an alternative embodiment of the mechanism of the invention, it comprises a single exhaust mobile provided with an odd number of peripheral teeth and arranged to mesh with reinforcement lugs, substantially merged with a virtual line passing through the pivot centers of said exhaust mobile and of said armature rocker, these armament lugs being formed on an internal field of an eyelet of the armament scale and according to a homothety of ratio k = -1 relative in the center of said eyelet.

In this embodiment, it is particularly critical to ensure that the cooperation of the teeth of the exhaust mobile with the winding pins implies a minimum variation of the driving torque of the winding rocker, despite the presence of the elastic compensation member. This implies in particular the adequate adjustment, at the structural level of the teeth and lugs so that the angles of lift at the exhaust mobile and at the arm lever and their penetrations in the two directions of rotation of the arm lever are the more similar possible. To do this, the inventors have advantageously been able to determine that the exhaust mobile and the winding rocker must be such that the ratio of the radius of said exhaust mobile (R _A ) to the center distance between this exhaust mobile and the cocking scale (R _B ) is less than 1/3.

In a second variant embodiment, the mechanism of the invention comprises two identical escapement mobiles each provided with peripheral teeth and capable of meshing with a mobile the work train of a clockwork movement to pivot simultaneously in the same direction around d '' a proper axis of rotation and meshing each with a winding lug formed on an internal field of first and second eyelets formed symmetrically on the winding rocker.

In these two alternative embodiments, the monostable elastic compensation member can be chosen as a leaf spring working in bending, a leaf spring working in buckling, or even a spiral spring.

In the various embodiments presented, the monostable elastic compensation member may be integral at a first end with a stud formed on the armature rocker and at a second end with an anchoring member to a frame element of a so-called watch movement or a timepiece.

In addition, the anchoring points of said bistable elastic blade are also preferably located on said anchoring member to a frame element of a timepiece movement or of a timepiece.

In a particular embodiment, the monostable elastic compensation member is a leaf spring made of material in monolithic form with a fixing frame to a frame element of a watch movement or a timepiece.

Similarly, the bistable elastic blade is also preferably made in one piece in monolithic form with said fixing frame to a frame element of a watch movement or a timepiece and the elastic compensation member.

Preferably, in particular for these monolithic embodiments, the bistable elastic blade and the monostable elastic compensation member are made of silicon. More particularly, the elastic blade and the monostable elastic compensating member, as well as the fixing frame from which they have come, if necessary, can be obtained by deep silicon etching processes.

The escape mechanism of the invention also advantageously comprises a locking lever arranged in kinematic connection with the trigger lever and configured to block the cocking lever in a first and a second extreme position outside the blade trigger phases elastic.

Preferably, the locking lever comprises a bar provided at one end with a fork connecting to said trigger lever and two locking arms extending symmetrically from one another from said bar and each provided at its free end of a locking pallet arranged to cooperate with a complementary locking member on said winding lever.

According to a preferred embodiment, said complementary locking member on said winding lever comprises a locking lug of shape and orientation suitable for hooking a said locking pallet of the locking lever.

Finally, the fork of the locking lever comprises two horns delimiting a space between horns into which is inserted an unlocking peg secured to the trigger rocker.

Brief description of the drawings

• les figures 1 à 9 représentent une première variante de réalisation du mécanisme d'échappement selon l'invention, comportant deux mobiles d'échappement et un ressort-lame monostable de compensation travaillant en flambement,
• les figures 10 à 18 représentent une seconde variante de réalisation du mécanisme d'échappement selon l'invention, comportant un seul mobile d'échappement et un ressort-lame de compensation travaillant en flexion,
• les figures 19 à 22 représentent les pénétrations respectives de mobiles d'échappements avec les anneaux d'armage de la bascule d'armage du mécansime de l'invention dans les deux variantes de réalisation décrites.

Other characteristics of the present invention will appear more clearly on reading the description which follows, made with reference to the appended drawings, among which:

• the Figures 1 to 9 represent a first alternative embodiment of the exhaust mechanism according to the invention, comprising two exhaust mobiles and a monostable compensating leaf spring working in buckling,
• the figures 10 to 18 represent a second alternative embodiment of the exhaust mechanism according to the invention, comprising a single exhaust mobile and a compensating leaf spring working in bending,
• the Figures 19 to 22 represent the respective penetrations of escapement mobiles with the cocking rings of the cocking lever of the mechanism of the invention in the two variant embodiments described.

Mode (s) of Carrying Out the Invention

We have represented on the figure 1 an escapement mechanism for a timepiece movement according to the invention in a first embodiment. This exhaust mechanism comprises a first and a second escape wheel 4, 5 movable each in rotation respectively about a first axis D and a second axis G. The two escape wheels 4, 5 mesh a mobile of the clockwork of a watch movement (of which only the fifth wheel 8 and the pendulum 0 are shown in the figures), in this case a fifth wheel 8 movable in rotation about an axis H, by the intermediate a first and a second exhaust pinion 6, 7 respectively coaxially integral with said first and second exhaust wheels 4,5.

The escape wheels 4, 5 are arranged to transmit a portion of mechanical energy from a driving source of the watch movement, typically a or several barrel springs, with motion regulator, formed of a pendulum 0 arranged to be movable in rotation about an axis K and carrying, in a conventional manner, a double plate 1 provided on its large plate with a dowel pin 1a. The escape wheels 4, 5 cooperate to do this with a winding lever 3 pivotally mounted about an axis F and a bistable leaf spring L. The bistable leaf spring L is formed by an elastic blade initially straight whose ends A, B have been brought symmetrically with respect to a midpoint to constrain said blade in buckling such that the latter is able to pivot around said midpoint, forming the point of inflection of the bistable leaf spring L, this inflection point being situated on the axis F of rotation of the winding lever 3. The bistable leaf spring L thus comprises on either side of its inflection point two half-blades 10a, 10b elastic, each having in a state of rest, said stable state, an opposite concavity of the other half-blade. The ends A, B forming anchors of the bistable leaf spring L are advantageously secured to a frame 10e capable of being fixed on a frame, for example a plate, of the watch movement, said frame 10e thus providing by construction the necessary buckling stress on the bistable leaf spring L, therefore on the half-blades 10a, 10c.

Preferably, the bistable leaf spring L, the two half-blades 10a, 10c and the frame 10e are advantageously formed as a monolithic piece of silicon by deep etching processes, which makes it possible to obtain extremely dimensioned pieces. precise in accordance with the constraints and performances calculated beforehand as a function of the dimensions of the other parts of the escapement but also of the timepiece movement in which said escapement mechanism is implemented.

Said bistable leaf spring L is intended, in a manner known per se, to accumulate the mechanical energy of the driving source of the movement transmitted by the escapement wheels 4, 5 to the winding lever 3 in the form of a torque d dextral drive M _d ( Figure 2 , 3 ), respectively senestre M _g ( Figure 6 , 7 ), of said winding lever 3 around the axis F, said winding lever 3 being integral with the bistable leaf spring L substantially at the midpoints of each half-leaf 10a, 10b located on either side of the inflection point of the bistable leaf spring L.

The connection of the arm lever 3 to each half-blade 10a, 10b is advantageously carried out at the ends of two arms of said arm lever 3 by means of two arm pins 10, 3f inserted in eyelets 10e , 10f corresponding formed of material in the middle of each half-blade 10a, 10b. The winding rocker 3 advantageously has symmetry along a median plane passing through the axes of rotation F, respectively K of the winding rocker, respectively of the oscillator, so that the connecting points of the connecting arms of the winding lever 3 to the bistable leaf spring L are equidistant from the axis of rotation F of said winding lever by a distance R _e , and thus suitable for applying to the middle of each half-leaf 10a, 10b a winding force F _e of the bistable leaf spring 10 providing a winding torque M _e capable of passing each half-blade 10a, 10b from a stable state to a metastable state called winding (shown in the figures 2 , 3 , 6 , 7 by lines in strong solid lines of each half-blade) in which each half-blade 10a, 10b is charged with an elastic energy then discharged and transmitted to the balance 0 by means of a trigger lever 2.

The trigger lever 2 is arranged integral with the leaf spring L at its point of inflection and therefore movable in rotation itself also around the axis F, common to the winding lever 3. However, the trigger lever 2 is independent in rotation of the cocking lever 3. The trigger lever 2 has ( Figure 1B ) conventionally a fork for cooperation with the plate pin 1a of the double plate 1 of pendulum 0, said fork comprising internal horns 2b, 2c and external 10i, 10j as well as a central dart 2a intended to prevent any overturning as in an anchor escapement. The trigger lever 2 thus pivots about the axis F only under the action of the plate pin 1a in its detent horns 2b, 2c during the alternations of the balance 2, thus transmitting to the latter the accumulated elastic energy in the armored state of the bistable leaf spring L.

According to an advantageous embodiment, the trigger lever 2 can be formed monolithically with the bistable leaf spring L, so that the axis of rotation F of the trigger lever 2 coincides at the point of inflection Median of the bistable leaf spring L. Advantageously also, the movements of the trigger lever 2 are limited by stops in the form of pins or locks I, J for example integrated in monolithic form also with the 10th frame and the leaf spring L, the whole constituting a single piece 10 fixed on the plate of the watch movement.

At one end opposite to its fork, said trigger lever 2 comprises an unlocking pin 2d, inserted into a link fork of a locking lever 9 of the arm lever 3. This locking lever 9 is intended to operate the locking of said winding lever 3 in the dextral (clockwise rotation of said winding lever 3) and senestre (counterclockwise rotation of said winding lever 3) arming positions of the bistable leaf spring L, in which each half-blade 10a, 10b of the latter are in their metastable state of reinforcement. The locking lever 9 is mounted movable about an axis of rotation H, in the example presented common to the fifth wheel 8, but which could also be arranged otherwise. It comprises a central bar 9e, one free end of which, opposite the axis of rotation H, comprises first and second unlocking horns 9a, 9b defining the connection fork to the trigger lever 2, between which the release pin 2d. Opposite the unlocking horns 9a, 9b extend symmetrically with respect to the axis of rotation H and the central bar 9e two locking arms carrying at their free end a right locking pallet 9c and a pallet left locking device 9d respectively, arranged to cooperate with locking pins 3c, 3d of the arm lever 3, formed on a locking tail 3k of said locking lever 3, said locking tail being visible in more detail on the figures 4 and 5 .

The winding of the bistable leaf spring L results, as mentioned above, from the transmission of the mechanical drive torque from the driving source of the watch movement to the winding lever 3. This torque transmission takes place according to the exhaust mechanism of the invention by meshing the teeth of the escapement wheels 4,5 with reinforcement lugs 3a, 3b formed on an internal field of a first and a second winding ring 3i, 3j, equidistant from the median axis of the winding lever 3 like the arms connecting to the bistable leaf spring L, said winding rings 3i, 3j each delimiting an oblong opening in which is housed one of the escape wheels 4, 5.

More particularly, the first escape wheel 4 extends in the oblong opening delimited by the winding ring 3i, and the second escape wheel 5 extends in the opening of the winding ring 3j . The winding ring 3i comprises a winding lug 3a arranged on an internal field of the external edge of the ring 3i, that is to say the edge furthest from the axis of rotation F of the rocker armament 3, and the armament ring 3j has a armament lug 3b arranged on an internal field of the inner edge of the ring 3j, that is to say the edge closest to the axis of rotation F of the cocking lever 3. This particular configuration of the cocking rings 3i, 3j and the arrangement of the escapement wheels 4, 5 in the openings thereof provides a decoupling of the dexter cocking functions and armamentary cocking of the cocking lever 3 on the escape wheel 4 in the cocking ring 3i for dextral cocking on the one hand, and on the escape wheel 5 in the ring d 3j armage for the main armament on the other hand, as will be described in detail below.

Thus, the escape wheel 4 meshes with said winding pin 3a of the winding ring 3i during dextrous winding phases of the bistable leaf spring L, the second escape wheel 5 then being devoid of contact with the cocking pin 3b of the cocking ring 3j. Conversely, the escape wheel 5 meshes with said winding lug 3b of the winding ring 3j during phases of winding the bistable leaf spring L, the first escape wheel 4 then being without contact with the cocking lug 3a of the cocking ring 3i.

According to this configuration, the distances R _d , R _g of application of the winding forces F _d , F _g applied by the teeth of the escape wheels 4, 5 on the winding pins 3a, 3b relative to the axis F during the dexter and senestre arming phases of the arming lever 3, are different, and therefore the dexter arming couples M _d and senestre M _g applied by each escape wheel 4, 5 are necessarily different, the lever arm R _g , and therefore the winding torque M _g , senestre being in practice less than the lever arm R _d and the dexter winding torque M _g while the applied forces F _d , F _g are equal (the gear ratio of the escape wheels 4,5 with the fifth wheel 8 is preferably equal), which causes the same potential drawbacks as those identified of the previous mechanism described in WO 2018/002773 .

These drawbacks are however eliminated in the mechanism of the invention by the provision of a device for compensating for this difference in the dexter armor pairs M _d and the senescent M _g , this compensatory device consisting essentially of the provision of an elastic member monostable 10c for compensating for a variation in the driving torque of the winding lever 3 by the exhaust mobiles 4, 5 according to the dexter and senestre winding rotations.

In the embodiment shown, the elastic compensation member advantageously consists of a monostable leaf spring 10c arranged to exert a restoring force complementary to the winding force applied by the escape wheel 5 on the lug 3b of the rocking arm 3 during the phases of the armament, said monostable leaf spring 10c preferably working in buckling. However, it should be noted that in this embodiment, it could also provide a compensating leaf spring 10c working in bending, or even a spiral spring arranged between the frame of the movement for example and the winding lever 3.

The compensating leaf spring 10c preferably extends from a first anchor point C on the frame 10e and a second anchor point on the tail 3k of the arm lever 3, formed for example in the form presented by an eyelet 10g at the end of the compensating leaf spring 10c adjusting with play in a stud secured to a tail 3k of the arm lever 3, at the base of the release horns 9a, 9b of the fork of locking lever 9. Advantageously, the compensating leaf spring 10c can also be obtained in monolithic form with the frame 10e and its bistable leaf spring L, which comprises two half-blades 10a, 10b connected together by a part 10d of the trigger rocker. This monolithic assembly can in particular be made of silicon, by deep etching processes, well known in the field of watchmaking and microtechnology in general.

The operation of the exhaust mechanism of the invention and its operating conditions will now be presented in detail with reference to figures 2 to 9 , which show a complete operating cycle on two half-waves of the pendulum 0 of the associated watch movement, each half-wave of the pendulum 0 comprising at the escapement an arming and locking phase during the additional arc of the pendulum, followed by a unlocking phase, and an expansion phase during the lifting angle.

The figures 2 to 5 represent a first alternation of the pendulum 0 with arming and locking during the additional arc of the pendulum 0 then an unlocking and dexter trigger operating during its angle of lift, the arm 3 and trigger 2 rockers successively rotating in one direction dextral rotation, that is to say with a rotation in direction.

The dextral arming phase ( Figure 2 ) is initiated when a tooth of the escapement wheel 4, driven by the fifth wheel 8 in a clockwise movement, meshes the winding lug 3a of the winding ring 3i, thus applying to the point of meshing a force F _d with a lever arm R _d relative to the axis F of rotation of the winding lever 3, providing a dexter winding torque M _d . This dextrous winding torque M _d rotates the winding lever 3 around its axis F clockwise, which imposes what requires the two half-blades 10a, 10b to leave a stable state for a metastable state and therefore to cause, by reaction of the bistable elastic blade L, forces F _e acting on the winding lever 3 by means of the eyelets 10e, 10f acting on the tenons 3e, 3f (represented by the lines in strong lines ), without the trigger lever 2 moving. Concomitantly, the dextral rotation of the winding lever 3 also constrains the compensating leaf spring 10c which also undergoes buckling. The monostable compensation leaf spring 10c thus applies a reaction force F _c to the winding lever 3 by its eyelet 3g on the lug 3g of the winding lever 3

At the end of the dexter arm rotation of the arm latch ( figure 3 ) the locking pin 3d of the tail 3k of the lever rocker 3 engages the locking pallet 9d of the lever lever 9 and hooks with it, operating the dexter lock of the lever lever 3, and then blocking the leaf spring bistable L in a metastable state, the monostable compensation spring 10c being in turn in a state close to its maximum arming state. Throughout the dexter arming and dexter locking phase, the trigger lever 2 is substantially stationary, in stable support by the right outer horn 10j against the bar J, the pendulum 0 finishing traversing its additional ascending dexter arc or begins its additional descending arch. At the end of the locking phase the pendulum 0 begins its return to neutral and its second alternation in counterclockwise rotation on its axis, that is to say its additional descending sinister arc.

The dexter unlocking phase begins when the plate pin 1a comes into contact with the left inner horn 2b of the trigger lever 2 and ends when this pin is substantially on the center line. This unlocking, analogous to the release of the anchor in a Swiss anchor escapement, induces an inflection of the bistable leaf spring L around its inflection point I which leaves its metastable state to reach its unstable state proper, this thanks to the dexter rotation of the trigger lever 2 about its axis F. Once the unstable state of the leaf spring L is exceeded, the rotation of the trigger lever 2 undergoes the relaxation of the bistable leaf spring L which transmits the elastic energy accumulated in its unstable state of armament at pendulum 0 and then goes into a second stable state of rest, in which the concavity of the half-blades 10a, 10b is reversed with respect to that of the start of arming, shown in the figure 1 or 2 . On the other hand, the compensating leaf spring 10c itself remains in the armed state and in fact even more constrained due to the complementary rotation of the winding lever 3 clockwise following the expansion of the bistable leaf spring L, up to 'so that the trigger lever 2 comes into abutment on the left outer horn 10i against the bar I, the plate pin 1a then leaves the trigger fork and starts its additional arc on the second half-wave of the pendulum 0 ( figures 6 and 7 ). At this instant, the pallet 9d of the locking lever 9 detaches from the hook 3d, thereby releasing the cocking lever 3, which is free to pursue a small dexter unlocking angle sufficient for its cocking pin. 3a frees the tooth of the armament mobile 4 hitherto engaged. The two winding wheel, both meshing with their winding pinion 6, 7 at the wheel fifth 8 rotate in concert until a tooth of the winding wheel 5 meets the winding lug 3b of the winding lever 3, then initiating the phase of winding the bistable leaf spring 10 ( figure 6 ).

The meshing of the tooth of the escape wheel 5, which is also driven by the fifth wheel 8 in a clockwise movement, with the winding lug 3b of the winding ring 3j, this time applies to the point of engagement a force F _g with a lever arm R _g with respect to the axis F of rotation of the rocking armage 3, providing a couple of senestrial armament M _g . This semester winding torque M _g is necessarily less than the dexter winding torque M _d insofar as the lever arm R _g is less than the lever arm R _d of application of the force F _d on the lug 3a . In practice, due to this inherent structural difference, the torque winding sinistral M _g is insufficient to rotate the rocker winding 3 about its axis F counterclockwise and bring the half-strips 10a, 10b to their metastable arming state (represented by the solid solid lines). However, the compensating leaf spring 10c then compensates for the lack of arming torque M _g of the escape wheel 5 by the progressive release of the elastic energy accumulated during the arming and dexter expansion phases, which induces a thrust F _c on the tail 3k of the winding lever 3, and therefore a compensation torque M _e which, added to the winding torque M _g , is able to overcome the feedback torque 2 x F _e x R _e necessary to produce the armature of the bistable leaf spring L.

At the end of the armary rotation of the armory rocker ( figure 7 ) the locking pin 3c of the tail 3k of the rocking lever 3 engages the locking pallet 9c of the locking lever 9 and hooks with it, operating the senestrial locking of the lever lever 3, and then blocking the bistable leaf spring L in a metastable state. During the entire phase of the armament and the senestral lock, the trigger lever 2 is substantially stationary, in stable support by its left outer horn 10i against the bar I, the pendulum 0 traversing all of its additional ascending semester arc and possibly a part of its additional descending dexter arc. At the end of the locking phase the pendulum 0 finishes its additional dexter arc descending towards the angel next lift, itself consisting of an unlocking and a senestre trigger. The compensating leaf spring 10c is practically discharged, close to rest ( figure 8 )

The senestre unlocking phase begins when the plateau pin 1a comes into contact with the right inner horn 2c of the trigger lever 2 and ends when this pin is substantially on the center line. This unlocking, analogous to the release of the anchor in a Swiss anchor escapement, induces an inflection of the leaf spring L around its inflection point I which leaves its metastable state to reach its unstable state proper, this thanks to the rotation of the trigger flip-flop 2 around its axis F. ( figures 8 and 9 ). At this instant, the pallet 9c of the locking lever 9 detaches from the locking pin 3c, thereby releasing the winding lever 3. The rotation of the trigger lever 2 causes the bistable leaf spring 10 to relax. transmits the elastic energy accumulated in its metastable state of winding to the pendulum 0 and then passes into its first stable state of rest, shown in the figure 1 . The compensating leaf spring 10c is then also in a disarmed state, and almost unstressed, only has a low state of elastic deformation energy. At the end of the trigger, the bistable leaf spring L is again in a stable state, ready for a new dextral winding and so on.

The exhaust mechanism of the invention can also be declined in a second embodiment comprising a single escape wheel 4, like the proposal made in WO 2018/002773 . This second embodiment is shown in a preferred embodiment in figures 10 to 18 .

• la procuration d'un unique mobile d'échappement 4 muni d'un nombre impair de dents périphériques et agencé pour engrener avec des ergots d'armage 3a, 3b formés sur un champ interne d'un unique anneau d'armage 3i de la bascule d'armage 3, selon une homothétie de rapport k=-1 par rapport au centre dudit anneau d'armage 3i ;
• la procuration d'un ressort-lame monostable de compensation 10c travaillant en flexion entre un tenon 3g inséré dans la bascule d'armage 3 grâce à un oeillet 10g fabriqué préférentiellement dans le ressort-lame monostable 10c même, l'extrémité opposée du ressort lame monostable 10c étant solidaire en un point d'encastrement C d'un cadre de soutien 10h, lui-même pouvant supporter en des points d'encastrements A, B les demi-lames élastique 10a, 10b.

With reference to figures 10a to 10c , the exhaust mechanism has a structure completely similar to that of the embodiment of the Figures 1 to 9 , with the exception of :

• the provision of a single exhaust mobile 4 provided with an odd number of peripheral teeth and arranged to mesh with cocking pins 3a, 3b formed on an internal field of a single cocking ring 3i of the rocker of armament 3, according to a homothety of ratio k = -1 relative to the center of said winding ring 3i;
• the provision of a monostable compensating leaf spring 10c working in bending between a lug 3g inserted in the reinforcement lever 3 thanks to an eyelet 10g preferably produced in the monostable leaf spring 10c itself, the opposite end of the leaf spring monostable 10c being secured at a mounting point C of a support frame 10h, itself capable of supporting at mounting points A, B the elastic half-blades 10a, 10b.

Note, however, that in this embodiment, it could also provide a compensating leaf spring 10c working in buckling as in the first embodiment, or even a spiral spring arranged between the frame of the movement for example and the arming scale 3.

The rest of the exhaust mechanism and its operation are in fact strictly analogous, as described below with reference to figures 11 to 18 .

The dextral arming phase ( figure 11 ) is initiated when a tooth of the escapement wheel 4, integral with its pinion 6, itself meshing with the fifth wheel 8 in a dextrous rotation, meshes with the winding pin 3a located on the upper arm ( with reference to the figure) of the winding ring 3i, thus applying to the point of engagement a force F _d with a lever arm R _d relative to the axis F of rotation of the winding rocker 3, providing a dextral winding torque M _d . This dexter winding torque M _d rotates the winding lever 3 around its axis F clockwise, which makes it possible to overcome the force couple 2 x F _e x R _e coming from the feedback produced by the bistable elastic spring L by its two eyelets 10e, 10f formed in its two half-blades 10a, 10b acting on the lugs 3e, 3f of the winding lever 3, without the trigger lever 2 not moving. Concomitantly, the dextral rotation of the winding lever 3 also constrains the compensating leaf spring 10c which in this case undergoes simple bending. The compensating leaf spring 10c thus applies a force to the armature lever. of reaction F _c by its tenon 3g with a lever arm R _c , inducing a torque opposite to the dexter winding torque M _d .

At the end of the dexter arm rotation of the arm latch ( figure 12 ) the locking lug 3d of the latch 3, located on the right external field of the letting ring 3i, engages the locking pallet 9d of the latch 9 and hooks with it, operating the locking dexter of the winding lever 3, and then blocking the bistable leaf spring 10 in a metastable state and the compensating leaf spring 10c in bending. Throughout the dexter arming and dexter locking phase, the trigger lever 2 is substantially stationary, in stable support by its right outer horn 10j against the bar J, the pendulum 0 finishing traversing its additional ascending dexter or beginner arc its additional descending arch.

The escape wheel 4 then disengages from the winding lug 3a when a tooth from the escape wheel 4 in turn engages the lug 3b from the winding ring 3i, which corresponds substantially to the moment. unlocking ( figure 13 ) effective either after the moment when the plateau pin 1a comes into contact with the right horn 2b of the trigger lever 2 but substantially before the moment when the plateau pin 1a is on the center line, initiating the trigger phase dexter ( figure 13 and 14 ). At this instant, the pallet 9c of the locking latch 9 detaches from the locking lug 3c, thus releasing the arming latch 3 for the phase of arming the bistable leaf spring 10 ( figure 15 ). The plateau pin 1a strikes the left horn 2b of the trigger lever 2, inducing the inflection of the bistable leaf spring 10 around its point of inflection on the axis F simultaneously with the rotation of the lever detent 2. Initially corresponding to the unlocking phase, the rotation of the detent lever 2 is driving with respect to the bistable leaf spring L and allows it to leave its metastable state (close to its unstable state) to reach the unstable state proper. In a second step corresponding to the expansion phase, once this unstable state is exceeded, the bistable leaf spring L becomes a motor vis-a-vis the trigger lever 2 and transmits its accumulated energy to the balance 0 and then passes into a second stable state of rest, in which the concavity of the half-blades 10a, 10b is reversed with respect to that of the start of winding up, shown in the figure 10 or 11 . On the other hand, the compensating leaf spring 10c itself remains under maximum bending stress, the complementary dextral rotation of the winding lever 3 clockwise then being maximum, the trigger lever 2 abuts on its left outer horn 10i against the label I. The dowel pin 1a then leaves the fork of the trigger lever 2 and begins its additional ascending arc on the second half-swing of pendulum 0 ( figures 15 and 16 ).

During the arming phase, while the trigger lever 2 presses against the left bar I, a tooth of the escape wheel 4 meshes with the cocking pin 3b of the cocking ring 3j, this time thus applies to the point of engagement a force F _g with a lever arm R _g with respect to the axis F of rotation of the arm lever 3, providing a couple of armament senestre M _g . This semester winding torque M _g is necessarily less than the dexter winding torque M _d insofar as the lever arm R _g is less than the lever arm R _d of application of the force F _d on the lug 3a . The compensating leaf spring 10c then compensates for the lack of arming torque M _g of the escape wheel 4 by the progressive release of the elastic energy accumulated during the arming and dexter unlocking phases, which induces a thrust F _c on the rocking arm 3, and therefore a compensation torque M _c which, added to the earthly arm torque M _g is able to overcome the feedback couple 2 x F _e x R _e necessary to produce reinforcement of the bistable leaf spring L.

At the end of the armoring of the armor rocker ( figure 16 ) the locking pin 3c of the cocking lever 3, located on the left external field of the cocking ring 3i engages the locking pallet 9c of the locking lever 9 and hooks with it, operating the senestrial locking of the rocking arm 3, and then blocking the bistable leaf springs L in a metastable state. During all the phase of the armament and the lock, the trigger 2 is substantially stationary, in stable support by its right outer horn 10j against the label J, the pendulum 0 finishing to travel its additional ascending or beginning semester arc its additional dexter arc descending at the end from the locking phase, the pendulum 0 begins its return to neutral, ie its additional descending dexter arc. The compensating leaf spring 10c is in a lower arming state than that which existed when the arming lever 3 was in the dextral locking position ( figure 13 ).

The senestre unlocking phase begins when the plateau pin 1a comes into contact with the right inner horn 2c of the trigger lever 2 and ends when this pin is substantially on the center line. This unlocking, analogous to the release of the anchor in a Swiss anchor escapement, induces an inflection of the leaf spring L around its inflection point I which leaves its metastable state to reach its unstable state proper, this thanks to the rotation of the trigger flip-flop 2 around its axis F. ( figures 17 and 18 ). At this instant, the pallet 9c of the locking lever 9 detaches from the locking pin 3c, thereby releasing the cocking lever 3. The expansion phase begins when the trigger lever 2 becomes driven and therefore when its left horn 2b strikes the plateau pin 1a. To do this, once the unstable state of the leaf spring L is exceeded, the rotation of the trigger lever 2 undergoes the relaxation of the bistable leaf spring L which transmits to it the elastic energy accumulated while it was in its unstable armament state in the balance wheel and then goes into its stable armament state, shown in the figure 17 or 18 . The compensating leaf spring 10c is then also in a weakly armed state and therefore weakly stressed and only has a low state of elastic deformation energy. At the end of the trigger, the bistable leaf spring L is again in a state of rest, ready for a new dextral winding and so on.

As can be understood from the above description, the mechanism of the invention thus makes it possible, whatever the embodiment considered, to overcome the variations in winding torque applied to the rocking lever 3 by one or more wheels of escapements cooperating in engagement with said winding rocker in the direction of rotation, variations inherent in such a mode of driving the rocking rocker. The monostable compensating leaf spring 10c, whether it is designed to work in buckling or in bending, or whether it is in a spiral, allows with an appropriate dimensioning according to known calculation principles. of those skilled in the art, to adapt the return force of said monostable compensating leaf spring as a function of the dimensions of the other elements of the exhaust mechanism and of the characteristics of the bistable elastic blade L, which makes it possible to guarantee the tilting alternating the rocker armament 3 in a perfectly balanced manner, without unnecessary loss of energy or risk of blockage, with increased efficiency compared to similar exhaust mechanisms.

Où:

• F_e est la force appliquée par la bascule d'armage sensiblement aux milieux des demi-lames 10a 10b ;
• R_e est le bras de levier de la force F_e par rapport à l'axe F de rotation de la bascule d'armage ;
• R_c est le bras de levier de la force F_c par rapport à l'axe F de rotation de la bascule d'armage
• R_g est le bras de levier de la force F_g d'armage sénestre par rapport à l'axe F de rotation de la bascule d'armage
• R_d est le bras de levier de la force F_d d'armage dextre par rapport à l'axe F de rotation de la bascule d'armage.

The effective compensation of the differences in dextral and senestrian winding couples of the bistable leaf spring 10 implies being able to design and produce the elastic compensation member, that is to say the compensation leaf spring 10c, in an appropriate manner. so that it produces only the force F _c required to exactly compensate for the variation in the dexter arm pairs M _d = F _d x R _d and senestra M _g = F _g x R _g due to the difference in the lever arm R _d > R _g when the arming of the half-blades 10a, 10b of the bistable leaf spring L requires the maximum arming torque M _e = F _e x R _e at the arming lever 3. The inventors have thus determined that this compensating force Fc could be determined according to the following relation: $${\mathit{F}}_{\mathit{vs}}=2\cdot {\mathit{F}}_{\mathit{e}}\cdot \frac{{\mathit{R}}_e}{{\mathit{R}}_{\mathit{vs}}}\cdot \frac{{\mathit{R}}_{\mathit{g}}-{\mathit{R}}_{\mathit{g}}}{{\mathit{R}}_{\mathit{g}}+{\mathit{R}}_{\mathit{d}}}$$

Or:

• F _e is the force applied by the winding lever substantially in the middle of the half-blades 10a 10b;
• R _e is the lever arm of the force F _e with respect to the axis F of rotation of the winding lever;
• R _c is the lever arm of the force F _c with respect to the axis F of rotation of the winding rocker
• R _g is the lever arm of the force F _g of the armament relative to the axis F of rotation of the arm rocker
• R _d is the lever arm of the winding force F _d dexter with respect to the axis F of rotation of the winding rocker.

By changing the variables to express the maximum winding torques (M _e = 2 x F _e x R _e ) and correction (M _c = F _c x M _c ) rather than the relative forces F _e and F _c , we can express the correction torque according to the following simplified relation: $${\mathit{M}}_{\mathit{vs}}={\mathit{M}}_{\mathit{e}}\cdot \frac{{\mathit{R}}_{\mathit{g}}-{\mathit{R}}_{\mathit{g}}}{{\mathit{R}}_{\mathit{g}}+{\mathit{R}}_{\mathit{d}}}$$

In other words, it is thus possible to design and produce the compensating leaf spring 10c knowing the mechanical characteristics of the bistable leaf spring L, determining the maximum winding moment necessary for the passage of the half-leaves 10a, 10b d '' a stable state of rest at their metastable state of arming, as well as the arms of dextral and senestrial arming determined by the distance of application of the arming force of the escape wheel (s) 4, 5 relative to the axis F of rotation of the winding lever 3.

Other parameters are also to be taken into account in order to guarantee an optimal construction of the exhaust mechanism of the invention. These parameters are in particular the angles of lift (α _d , α _g ) dexter and senestre of the escape wheel (s) 4, 5, the angles of lift (ε _d , ε _g ) dexter and senestre of the armament scale 3, or even the dexter and senestral penetrations (P _d , P _g ) between the escape wheel (s) 4, 5 and the armament scale 3. These various parameters are notably represented on the Figures 19 to 22 . However, it appears that it is difficult, if not impossible, to reconcile, by the same construction, the theoretical optimal operating conditions for each of these parameters. Indeed, if we consider the lifting angles (α _d , α _g ) dexter and senestre of the escape wheel (s) 4, 5, it is preferable to have these equivalent (α _d = α _g ). However, this condition then imposes a lower dexter penetration than the senestral penetration (P _d <P _g ) and the dexter lift angle of the rocker armage 3 will be lower than its senestial lift angle (ε _d <ε _g ).

Similarly, if we want equivalent lifting angles of the rocker arm (ε _{d =} ε _g ), then the dexter penetration will be stronger than the senestral penetration (P _d > P _g ) and the angle dexter lift of the escape wheel will be lower than its senestrial lift angle (α _d , α _g ).

Finally if one wishes to obtain equal penetrations (P _d = P _g ) between the escape wheel (s) 4, 5 and the winding lever 3 then the lifting angle dexter of the wheel d the escapement will be stronger than its senestial lifting angle (α _d , α _g ) and the dexter lifting angle of the winding lever will be smaller than its senestrial lifting angle (ε _d <ε _g ).

Thus, none of the individual construction optima mentioned above makes it possible to reach the optimums of the other parameters simultaneously. However, the inventors have been able to determine that under all the optimal conditions considered for each construction parameter above, the defects listed on the other parameters will be all the less important as the ratio between the radius R _a of the (the ) escape wheel (s) 4, 5 and the center distance R _b between this (these) escape wheel (s) 4, 5 and the winding lever 3 will be small. To minimize these defects, it is therefore necessary, in all cases, to minimize the ratio R _a / R _b , the latter ideally ideally being less than 1/3.

The present invention has been described above with reference to two preferred particular embodiments making it possible to demonstrate the relevance of the implementation of a monostable elastic member compensating for winding torque of a bistable leaf spring in the frame of a bistable spring escapement with one or more exhaust mobiles cooperating in the manner of a gear with a lever for winding the bistable spring. It goes without saying, however, that modifications could be made to these embodiments without departing from the scope of the claims. The arm lever 3 could take other forms than that presented, just as the monostable compensation spring could also be arranged differently from the form presented, provided that its return action on the arm lever 3 is consistent to the principles presented in the present invention. The locking of the cocking lever 3 could also be carried out differently.

Claims (17)

Watch escapement mechanism, comprising: - A bistable elastic blade (L) working in buckling around a median point of inflection between two anchoring points (A, B) of said bistable elastic blade, an arm rocker (3) of said bistable elastic blade (L), mobile in rotation and kinematically linked in a direction substantially perpendicular to said elastic bistable blade at two points equidistant from the median point of inflection and - at least one escapement mobile (4, 5) integral with at least one pinion (6, 7) capable of meshing with a mobile (8) the work train of a watch movement, and arranged to sequentially transmit a drive torque to the winding lever (3) so as to rotate said winding lever alternately clockwise and counterclockwise to pass said bistable elastic blade (L) from a stable state of rest to a metastable state of arming, and - a trigger lever (2) secured to the bistable elastic blade (L) at its median inflection point (I) and arranged to cooperate with a regulating member (0) oscillating with a said clock movement at each alternation of that this so as to transmit to it a pulse following an expansion of the bistable elastic blade (L) corresponding to the transition from a said winding state to a said symmetrical rest state in the previous stable state of rest, characterized in that it comprises a monostable elastic member (10c) for compensating for a variation in the driving torque of the winding lever (3) by the mobile (s) of exhaust (4, 5 ) as a function of the direction of rotation of said winding lever (3). Exhaust mechanism according to claim 1, characterized in that the elastic monostable compensation member (10c) is coupled to the rocker armament (3) and arranged to exert on the latter a return torque in a single direction of rotation. Exhaust mechanism according to one of claims 1 or 2, characterized in that it comprises a single exhaust mobile (4) provided with an odd number of peripheral teeth and arranged to mesh with reinforcement lugs ( 3a, 3b) formed on an internal field of a winding ring (3i) of the winding lever (3) according to a homothety of ratio k = -1 relative to the center of said winding ring. Exhaust mechanism according to one of claims 1 or 2, characterized in that it comprises two identical exhaust mobiles (4, 5) each provided with peripheral teeth and integral with the pinion (s) (6, 7) able to mesh with a mobile (8) of the clockwork of a clockwork movement to pivot simultaneously in the same direction around separate axes of rotation and each mesh with a winding lug (4a, 4b) formed on an internal field of a first and a second winding ring (3i, 3j) formed symmetrically on the winding rocker (3), the indexing of these exhaust mobiles (4, 5) being such that when one of the reinforcement lugs (4a, 4b) meshes with one of the exhaust mobiles (4, 5), the other armament lugs (4a, 4b) is between two teeth of the other exhaust mobiles (4, 5). Exhaust mechanism according to claim 4 or 5, characterized in that the movable exhaust (s) (4, 5) and the cocking lever (3) are dimensioned and arranged so that the ratio of the radius (R _a ) of the exhaust mobile (s) at the center distance (R _b ) between the said mobile (s) of exhaust and the winding lever (3) is (are) such that: $$\frac{R_{\mathrm{at}}}{R_b}<1/3.$$

Exhaust mechanism according to one of claims 1 to 4, characterized in that the elastic monostable compensation member (10c) is a leaf spring working in bending. Exhaust mechanism according to one of claims 1 to 4, characterized in that the elastic monostable compensation member (10c) is a leaf spring working in buckling. Exhaust mechanism one of claims 1 to 4, characterized in that the elastic monostable compensation member (10c) is a spiral spring. Exhaust mechanism according to one of claims 1 to 8, characterized in that the elastic compensation member (10c) is a leaf spring secured at a first end (10g) to a stud (3g) formed on the winding lever (3) and at a second end (C) of an anchoring member to a frame element of a said watch movement or of a timepiece. Exhaust mechanism according to one of claims 1 to 9, characterized in that the anchoring points (A, B) of said bistable elastic blade (L) are located on said anchoring member to a frame element d '' a watch movement or a timepiece. Exhaust mechanism according to one of claims 1 to 10, characterized in that the elastic monostable compensation member (10c) is a leaf spring made of material in monolithic form with a fixing frame (10h) to an element of a watch movement or a timepiece. Escape mechanism according to claim 11, characterized in that the bistable elastic blade (L) has come in one piece in monolithic form with said fixing frame (10h) to a frame element of a timepiece movement or of a piece of watchmaking and the elastic compensation member. Exhaust mechanism according to one of claims 1 to 12, characterized in that the bistable elastic blade (L) and the monostable elastic compensation member (10c) are made of silicon. Escape mechanism according to one of claims 1 to 13, characterized in that it comprises a locking lever (9) arranged in kinematic connection with the trigger lever (2) and configured to block the cocking lever ( 3) in a first and a second extreme position outside the expansion phases of the elastic blade (L). Exhaust mechanism according to claim 14, characterized in that the locking lever (9) comprises a bar provided at one end with a fork connecting to said trigger lever (2) and two locking arms extending symmetrically to each other from said bar and each provided at its free end with a locking pallet (9c, 9d) arranged to cooperate with a complementary locking member (3c, 3d) on said arm lever ( 3). Escape mechanism according to claim 15, characterized in that said complementary locking member on said winding rocker comprises a locking lug (3c, 3d) of shape and orientation suitable for hooking a said locking pallet (9c , 9d) of the locking lever. Escape mechanism according to claim 15 or 16, characterized in that the fork of the locking lever (9) comprises two unlocking horns (9a, 9b) delimiting a space between horns in which a pin (2d) is inserted unlocking integral with the trigger lever (2).

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