EP3475763B1 - Clock escapement - Google Patents

Description

The present invention relates to a horological escapement, that is to say a mechanism used to maintain and count the oscillations of a horological regulator.

The present invention relates more particularly to an escapement comprising a bistable elastic member receiving energy from a driving member, for example a barrel, and communicating it to the regulator. An exhaust of this type is described in patent applications WO 99/64936 , WO 2009/118310 and CH 705674 . The bistable elastic member is a leaf spring working in buckling. The leaf spring is fixed by its two ends to recesses or to pivot members, and its midpoint is kept aligned with said two ends. The distance separating the two recesses is such that the leaf spring is subjected to compression which forces it to deform according to a second mode buckling. The leaf spring thus has two convexities in opposite directions on either side of its midpoint. The leaf spring can occupy two stable states, the passage from one of these stable states to the other being effected by reversing the direction of the two convexities.

In operation, a winding latch acting symmetrically in the area of the two convexities deforms the leaf spring from a first of its stable states to a metastable state close to an unstable state corresponding to a buckling of the fourth mode, in order to arm the leaf spring. Then a detent lever located in the mid-point zone acts on the leaf spring to make it go beyond its unstable state and thus make it switch to its second stable state by releasing its energy. The winding lever is actuated alternately by two escape wheels secured to escape gears which mesh with the last mobile of the finishing gear train of the timepiece. The trigger lever cooperates with a sprung balance regulator and for this purpose comprises a fork of the same type as the conventional anchor forks. Energy allowing the detent lever to deform the leaf spring beyond its unstable state from its metastable state is provided by the governor, when a chainring pin integral with the balance strikes a horn of the fork. This phase, which requires a small input of energy, can be compared to the release phase of an anchor escapement. The relaxation of the leaf spring, that is to say its passage from its unstable state to its second stable state, abruptly changes the inclination of the midpoint zone, which causes the trigger lever to pivot, which then communicates an impulse to the plateau peg. This phase, which releases a much greater energy, can be compared to the pulse phase of an anchor escapement. The difference lies in the fact that these two phases correspond to perfectly stable energy exchanges, which cannot be the case with an anchor escapement.

Instead of teeth, the escape wheels comprise winding cams at their periphery for actuating the winding lever. These winding cams end with locking stops. The winding phase of the leaf spring by the winding lever ends when the latter is blocked by one of the locking stops of the escape wheel with which it cooperates, which keeps the leaf spring in its position. metastable condition and immobilizes the two escape wheels, the finishing gear train and the winding lever. The deformation of the leaf spring from its metastable state to its second stable state under the action of the chainring pin and then of its relaxation causes a rotation of the winding lever which unlocks the escape wheels and brings the lever to winding in contact with the other escape wheel to start a cycle symmetrical to the previous one, after the impulse given to the plate pin.

A drawback of such an escapement lies in the fact that the succession of actions necessary to unlock the escape wheels is too long and makes imprecise the moment of the start of the pulse communicated by the expansion lever to the regulator. Indeed, to unlock the escape wheels, the winding lever is controlled by the leaf spring which is itself controlled by the trigger lever on which the regulator plate pin acts, and before driving the winding lever the leaf spring must catch up with the play that may exist between it and the winding lever. Unlocking is therefore ensured by a dynamic movement, that of the leaf spring, which is difficult to control and in addition through several components whose tolerances can vary the behavior. In addition, the force required for unlocking varies depending on the level of winding of the motor unit; it is greater when the level of arming of the motor unit is maximum. This has the consequence that the leaf spring is not always free at the same time to provide the impulse to the regulator and that the level of energy transmitted to the regulator also varies. The isochronism of the regulator is therefore affected.

The present invention aims to remedy these drawbacks, or at least to mitigate them, and to this end proposes a clock escapement comprising at least one escapement mobile, a bistable elastic member, a winding lever arranged to be driven. by the at least one escapement mobile in order to arm the bistable elastic member during winding phases, and a trigger lever arranged to be driven by a relaxation of the bistable elastic member after each winding phase in order to communicate an impulse to a regulator, the at least one escape mobile being locked after each winding phase and then unlocked, characterized in that the trigger lever is arranged to cooperate directly with the at least one mobile d 'exhaust for locking the at least one exhaust mobile.

Typically, for its cooperation with the at least one exhaust mobile, the expansion lever comprises an input member and an output member arranged to act alternately on the at least one exhaust mobile according to the alternations of the regulator.

The input and output members are for example nozzles.

Preferably, for its cooperation with the detent lever, at least one escapement mobile comprises at least one toothed wheel.

Advantageously, the horological escapement according to the invention comprises first and second limiting stops to limit the angular movement of the detent lever and when the at least one escapement mobile is locked, the at least one mobile exhaust presses the trigger lever against one of the first and second limit stops.

In particular embodiments, the trigger lever is arranged to cooperate with the bistable elastic member in the region of a midpoint of the bistable elastic member and the winding lever is arranged to cooperate with the elastic member bistable on either side of said zone.

Preferably, the horological escapement according to the invention comprises a single escapement mobile.

This escapement mobile can comprise a winding member arranged to cooperate with winding elements of the winding lever to cause the winding lever to pivot alternately in opposite directions.

The winding member and the winding elements can be arranged to cooperate with each other in the manner of a gear.

The winding elements are defined for example by an inner wall of part of the winding lever which surrounds the winding member.

Advantageously, said inner wall follows over substantially 360 ° the trajectory of the apex of a tooth of the winding member in a reference linked to the winding lever during rotation of the winding member, in order to abut against the winding member in the event of an impact and thus secure the position of the winding lever.

• les figures 1 à 5 montrent des configurations successives d'un échappement selon l'invention pendant un premier demi-cycle de fonctionnement ; et
• les figures 6 à 8 montrent des configurations successives de l'échappement selon l'invention pendant un deuxième demi-cycle de fonctionnement.

Other characteristics and advantages of the present invention will become apparent on reading the following detailed description given with reference to the appended drawings in which:

• the figures 1 to 5 show successive configurations of an escapement according to the invention during a first half-cycle of operation; and
• the figures 6 to 8 show successive configurations of the exhaust according to the invention during a second operating half-cycle.

With reference to the figure 1 , an escapement for a clockwork movement according to the invention comprises an escapement mobile 1, a bistable leaf spring 2, a winding lever 3 and an expansion lever 4.

The escape wheel 1 rotates around an axis A, in the direction indicated by the arrow F1, under the action of the movement motor member, typically formed by one or more barrels. The escapement mobile 1 comprises an escape pinion 5 which meshes with the movement finishing gear, a winding member 6 which, in the example shown, is in the form of a star, and a control wheel. locking 7 having inclined teeth 8 at its periphery. The escape pinion 5, the winding star 6 and the locking wheel 7 are coaxial and integral. The winding star 6 and the locking wheel 7 can be in one piece.

The winding lever 3 and the detent lever 4 pivot around the same imaginary axis B which corresponds to the midpoint of the leaf spring 2, but are free to pivot with respect to one another. In practice, the imaginary axis B is for example the axis of a rod (physical axis) driven into the winding lever 3, pivoting in bearings of the frame of the movement and around which the trigger lever 4 pivots. As a variant, however, the latches 3, 4 could be mounted on respective axes offset from one another, like the winding and detent levers described in the patent application. WO 99/64936 . In other variants, the rockers 3, 4 could not be mounted on physical axes but be guided around the same axis imaginary or two respective imaginary axes by flexible guidance systems.

In the example shown, the leaf spring 2 is integral with the detent lever 4 and consists of two elastic leaves 2a, 2b each having one end joined to the detent lever 4 and another end joined to the frame of the movement. Said other end of each elastic blade 2a, 2b can be joined to the frame of the movement by means of an outer frame (not shown) surrounding the leaf spring 2 and fixed to said frame, which outer frame can be integral with the spring -blade 2, as described in the patent applications WO 2009/118310 and CH 705674 . The leaf spring 2 can also be a piece attached to the detent lever 4 and to the outer frame.

The leaf spring 2 has two convexities of opposite directions on either side of its midpoint and can pass from a first stable state to a second stable state by reversing the direction of each of the two convexities. For this purpose, the leaf spring 2 is either pre-stressed so as to work in buckling or preformed to, in the rest state, already have two convexities as described in the international patent application. WO 2017/032528 of the present plaintiff. In the first case, the outer frame is deformable to allow buckling of the leaf spring 2. In the second case, the outer frame is rigid. The winding lever 3 comprises two arms carrying at their ends two pins 3a, 3b engaged in eyelets (not shown) of the two elastic blades 2a, 2b respectively. A reverse configuration is of course possible where the pins 3a, 3b would be carried by the elastic blades 2a, 2b, respectively, to engage in the eyelets of the winding lever 3. In addition, other connection modes between the winding lever 3 and the elastic blades 2a, 2b are conceivable, for example two pins at each end of the winding lever 3 clamping the corresponding elastic blade 2a, 2b.

The winding lever 3 further comprises a part 9 in the form of a ring which surrounds the winding star 6. The inner wall 10 of this part 9 has winding elements 11, 12 (cf. figure 2 ) formed by lugs, and is furthermore shaped irregularly to fulfill a safety function against shocks, that is to say to prevent rotation of the winding lever 3 beyond a certain play during a rotary or linear shock received by the clockwork movement. To this end, the inner wall 10 of part 9 follows over substantially 360 ° the trajectory of the apex of any one of the teeth of the winding star 6 in a reference linked to the winding lever 3 during the rotation of the winding star 6 and of the oscillations of the winding lever 3 which result therefrom, in order to abut against the winding star 6 in the event of an impact. In this way, the positioning of the winding lever 3 is guaranteed according to a small, predefined play, and thus prevents the winding lever 3 from triggering the tilting of the leaf spring 2 in an untimely manner.

The detent lever 4 comprises an inlet arm 13 terminated by an inlet spout 14 and an outlet arm 15 terminated by an outlet spout 16. These inlet and outlet spouts 14, 16 are arranged to cooperate with the teeth 8 of the locking wheel 7, as will be explained below. The trigger lever 4 also includes a rod 17 ending in a fork 18 similar to that of a traditional anchor, comprising a first horn 19 and a second horn 20. The fork 18 is arranged to cooperate with a plate pin 21 carried by a large plate 22 coaxial and integral with the movement regulator. The regulator (not shown) oscillates around an axis C, is for example of the sprung balance type but can also be an oscillator without a physical axis, with flexible blades. A dart 23 integral with the trigger lever 4, and which can be integral with the latter, is able to cooperate with a small plate 24 coaxial and integral with the regulator to prevent the reversal of the trigger lever 4 in the event of an impact. First and second limitation stops 25, 26 fixed relative to the frame of the movement limit the movement angular of the detent lever 4. These limiting stops 25, 26 are for example in the form of pins, as shown, or spigots. They can be integral with the outer frame of leaf spring 2.

The escapement according to the invention operates according to cycles each corresponding to an oscillation (two vibrations) of the regulator. Each cycle consists of two half cycles. Each half-cycle corresponds to an alternation of the regulator and includes the following phases: arming, locking, relaxation.

The winding phase of the first half-cycle begins when a tooth 6a of the winding star 6 meets a first, 11, of the winding elements 11, 12 of the winding lever 3 (cf. figure 1 ). By continuing to move, tooth 6a pushes this first winding element 11, which causes the winding lever 3 to pivot about its axis B in the direction indicated by arrow F2. This movement of the winding lever 3 arms the leaf spring 2 by making it pass from a first stable state to a metastable state close to an unstable state. This deformation of the leaf spring 2 is imperceptible in the region of the midpoint, so that the detent lever 4 remains stationary.

At the end of winding (cf. figure 2 ) a tooth 8a of the locking wheel 7 comes into contact with the inlet nose 14 of the trigger lever 4, which, by a pulling phenomenon, presses the trigger lever 4 against the first limit stop 25 and blocks the exhaust mobile 1 and with it the finishing gear. The locking phase has thus started. During this locking phase, the detent lever 4 is positioned precisely by the first limitation stop 25. This is an advantage over the state of the art ( WO 99/64936 , WO 2009/118310 and CH 705674 ) where the detent lever is positioned by the buckling rate of the leaf spring which applies rotational torque to the detent lever against a limiting stopper. This principle of the state of the art has the defect that under the action of winding the leaf spring, the trigger lever can move slightly and lose the contact with the limit stop. The trigger lever can thus vibrate during shocks or because of the natural frequency of the assembly comprising the trigger lever and the leaf spring. Such a vibration can be harmful because in certain cases the dart associated with the trigger lever can rub against the small plate and slow down the regulator. To avoid this kind of vibration, we can increase the buckling rate but at the cost of a decrease in efficiency. The present invention, by the pull exerted on the trigger lever 4 by the locking wheel 7, solves or at least mitigates this problem. In addition, the locking zone being relatively close to the axis of rotation B of the detent lever 4, the locking torque is potentially lower than in the state of the art.

These winding and locking phases occur while the regulator performs its additional arc, that is to say pivots around its axis C without interaction with the escapement. During these phases, the arming latch 3 is secured in position by the arming element 11 (in one direction) and by the inner wall 10 (in both directions). The leaf spring 2 therefore cannot change state inadvertently and the winding lever 3 cannot inadvertently unlock. At a determined instant after the locking of the escape mobile 1, the plate pin 21 strikes the internal face of the first horn 19 of the fork 18 (cf. figure 3 ), causing a slight pivoting of the trigger lever 4 in the direction F2. This pivoting causes a deformation of the leaf spring 2 causing it to go beyond its unstable state. The leaf spring 2 then releases the energy accumulated during winding by switching to its second stable state, the reverse of the first stable state. This is the relaxation phase. This sudden deformation of the leaf spring 2 causes the detent lever 4 to pivot in the direction F2. During this movement, the inlet spout 14 of the trigger lever 4 leaves the tooth 8a of the locking wheel 7, overcoming the support force exerted on said inlet spout 14 under the action of the member motor of the movement, and unlocks the exhaust mobile 1, then the internal face of the second horn 20 communicates an impulse to the plate pin 21 and therefore to the regulator (cf. figure 4 ). The relaxation phase ends when the relaxation lever 4 comes into abutment against the second limit stop 26 (cf. figure 5 ) in the second steady state of leaf spring 2.

After the relaxation phase begins the second half-cycle, with its winding, locking and relaxation phases occurring in the opposite direction to that of the first half-cycle. Thus, a tooth 6b of the winding star 6 comes into contact with a second, 12, of the winding elements 11, 12 of the winding lever 3 and pushes it to make the winding lever 3 pivot in a direction F3 opposite to the direction F2 (cf. figure 6 ). This movement of the winding lever 3 arms the leaf spring 2 to make it pass from its second stable state to a metastable state close to an unstable state. Then, a tooth 8b of the locking wheel 7 abuts against the outlet spout 16 of the trigger lever 4, which presses the trigger lever 4 against the second limit stop 26 and blocks the exhaust mobile 1 and with him the finishing gear (cf. figure 7 ). Then, the plate pin 21 strikes the internal face of the second horn 20 of the fork 18 (cf. figure 8 ), triggering the relaxation of the leaf spring 2, the unlocking of the exhaust mobile 1 and the communication of an impulse to the plate pin 21. At the end of this second half-cycle, the leaf spring 2 regains its first stable state, shown on figure 1 .

As emerges from the above description, the locking / unlocking of the exhaust mobile 1 in the present invention is effected directly by the detent lever 4 by means of the inlet and outlet nozzles 14, 16, therefore so static, rather than by the winding lever controlled by the leaf spring itself controlled by the trigger lever as in the state of the art. In the present invention the leaf spring 2 is only used for the impulse to the regulator. This makes it possible to unlock the exhaust mobile 1 sufficiently early, that is to say before the regulator reaches its equilibrium position, to leave the leaf spring 2 free to provide its impulse at the time timely, where the regulator is close to its equilibrium position. The instant of the start of the pulse can therefore be precise, which favors isochronism of the regulator.

In addition, the use of a single exhaust mobile 1 comprising the winding elements 11, 12 eliminates the need to index two exhaust mobile relative to each other, therefore facilitates assembly, and reduces bulk and inertia. In addition, the cooperation between the teeth of the winding star 6 and the winding elements 11, 12 generates little or no friction, unlike the mechanism winding cams according to documents. WO 99/64936 , WO 2009/118310 and CH 705674 , which slide on pins carried by the winding lever. Indeed, the cooperation between the winding star 6 and the winding elements 11, 12 is similar to that of a gear, the winding star 6 exerting a tangential force on the inner wall 10.

The present invention has been described above by way of example only. It goes without saying that modifications could be made without departing from the object claimed. For example, the winding star 6 and the locking wheel 7 could form a single piece on one level. In this case, the teeth of the star 6 would ensure in certain positions the winding and in other positions the locking. The bistable elastic member constituted by the leaf spring 2 could be formed from a single elastic leaf 2a or 2b and the winding lever 3 could comprise a single arm cooperating at its end with the elastic leaf. In variants, the bistable elastic member could comprise several leaf springs each comprising one or more elastic leaves. According to another modification, the exhaust mobile 1 could be located on the other side of the regulator or even be coaxial with said regulator (that is to say with the axis C). In addition, although the use of a single exhaust mobile 1 is preferred for the reasons indicated above, the exhaust according to the invention could comprise two exhaust wheels as described in the aforementioned documents. WO 99/64936 , WO 2009/118310 and CH 705674 , with which the inlet and outlet nozzles 14, 16 would cooperate respectively.

Claims (11)

1. Timepiece escapement comprising at least one escapement mobile (1), a bistable elastic member (2), a winding lever (3) arranged to be driven by the at least one escapement mobile (1) in order to wind the bistable elastic member (2) during winding phases, and a detent lever (4) arranged to be driven by a detent of the bistable elastic member (2) after each winding phase in order to communicate an impulse to a regulator, the at least one escapement mobile (1) being locked after each winding phase, then unlocked, characterised in that the detent lever (4) is arranged to cooperate directly with the at least one escapement mobile (1) to lock the at least one escapement mobile (1).
2. Timepiece escapement as claimed in claim 1, characterised in that, for the purpose of its cooperation with the at least one escapement mobile (1), the detent lever (4) comprises an input member (14) and an output member (16) which are arranged to act in an alternating manner on the at least one escapement mobile (1) depending on the vibrations of the regulator.
3. Timepiece escapement as claimed in claim 2, characterised in that the input and output members (14, 16) are beaks.
4. Timepiece escapement as claimed in any one of claims 1 to 3, characterised in that, for the purpose of its cooperation with the detent lever (4), the at least one escapement mobile (1) comprises at least one toothed wheel (7).
5. Timepiece escapement as claimed in any one of claims 1 to 4, characterised in that it comprises first and second limit stops (25, 26) to limit the angular movement of the detent lever (4) and in that, when the at least one escapement mobile (1) is locked, the at least one escapement mobile (1) presses the detent lever (4) against one of the first and second limit stops (25, 26).
6. Timepiece escapement as claimed in any one of claims 1 to 5, characterised in that the detent lever (4) is arranged to cooperate with the bistable elastic member (2) in the region of a middle point (B) of the bistable elastic member (2) and the winding lever (3) is arranged to cooperate with the bistable elastic member (2) on both sides (3a, 3b) of said region.
7. Timepiece escapement as claimed in any one of claims 1 to 6, characterised in that it comprises a single escapement mobile (1).
8. Timepiece escapement as claimed in claim 7, characterised in that the escapement mobile (1) comprises a winding member (6) arranged to cooperate with winding elements (11, 12) of the winding lever (3) to cause the winding lever (3) to pivot in an alternating manner in opposing directions.
9. Escapement as claimed in claim 8, characterised in that the winding member (6) and the winding elements (11, 12) are arranged to cooperate with each other in the manner of a gear.
10. Timepiece escapement as claimed in claim 8 or 9, characterised in that the winding elements (11, 12) are defined by an inner wall (10) of a part (9) of the winding lever (3) which surrounds the winding member (6).
11. Timepiece escapement as claimed in claim 10, characterised in that said inner wall (10) follows through substantially 360° the trajectory of the tip of a tooth of the winding member (6) in a guide-mark linked to the winding lever (3) during the rotation of the winding member (6), in order to abut against the winding member (6) in the event of an impact and thus secure the position of the winding lever (3).

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